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This is a division, of Application Ser. No. 142,040 filed Jan. 11, 1988 now abandoned.
BACKGROUND OF THE INVENTION
The present invention relates to wheelchair lifts and, in particular, to wheelchair lift apparatus for providing access from a landing to a vehicle.
In recent years, increasing sensitivity to the need to provide for the mobility of handicapped persons has resulted in a proliferation of lift devices for handicapped persons. One type of lift device enabling a handicapped person to use transit facilities is fixed to the landing and includes, as part of a lifting platform, an extendable bridge for providing access from the lifting platform laterally across the threshold to a light rail vehicle. Illustrative of such devices are German Patent No. P3325036.7, dated July 11, 1983; Williams, U.S. Pat. No. 5,576,539, dated Mar. 18, 1986; and Hussey, U.S Pat. No. 4,499 issued Feb. 19, 1985. In such lift devices, the bridge is interconnected to the platform rather than being independently mounted on a separate support structure. Also, such lifts require considerable space on the landing and hence creates a substantial obstruction to the free flow of non handicapped traffic around the lift device.
In order to overcome the obstruction problem which such lifts present, various mobile lifts have been devised which can be moved so they do not obstruct, For example, United Kingdom Patent No. 2,055,344 to Andersson illustrates a mobile lift which must be attached to the vehicle so as to provide the support necessary for the platform as it is being raised. Also, the bridge portion is hinged to the platform and hence raises and lowers with the platform. Kingston U.S. Pat. No. 4,564,096, dated Jan. 14, 1986 similarly shows a movable (transportable) lift which requires mounting or attachment to the rail vehicle to provide the necessary stability lost because of the mobility feature. The necessity to attach the lift to the rail vehicle greatly increases the time necessary to prepare the lift for use and poses significant risks of collapse if the attachment is done incorrectly.
O'Brian et al, U.S. Pat. No. 3,888,463, dated June 10, 1975 illustrates another wheelchair lift which is movable into a position extending at least part way under the vehicle thereby eliminating the need to attach the lift to the rail vehicle. Also, the platform has no bridge member but rather abuts directly against the threshold of the vehicle. Obviously, such an arrangement is not adaptable to a rail vehicle which also has steps. Finally, King Canadian Patent No. 1095462, issued Feb. 10, 1981, shows an apparatus for transferring wheelchair confined passengers between an aircraft and an aircraft tarmac. However, King discloses a bridge member which is necessarily attached to and moves with the platform as it is raised and lowered. Also, King does not provide a support structure as in the present invention.
SUMMARY OF THE INVENTION
The present invention comprises a lift apparatus for providing handicapped access from a landing to a guideway mounted vehicle and includes a support structure with a lift opening on a first side and a bridge opening on a second side opposite to the first side. The support structure includes a pedestal portion which has a top surface providing a connecting passageway and a housing extending upward from the pedestal where the housing has a passageway between the lift opening and the bridge opening A lift device is mounted in the lift opening of the support structure The lift includes a right linkage which has an upper end mounted to the housing alongside the passageway and a left linkage having an upper end mounted to the housing along the other side of the passageway opposite to the one side Both the right linkage and the left linkage have lower ends which are coupled to a platform whereby the platform is capable of pivotal movement about the lower ends of the right and left linkages. A cable or chain is attached on both sides of the platform to prevent pivotal movement of the platform below a generally horizontal position but allow upward pivotal movement into a storage position. A lift movement apparatus is coupled to selectively move the platform between a lowered position adjacent landing and a raised position adjacent the top surface of the pedestal and thereafter to selectively pivot the platform between the raised position and a vertical storage position in the passageway adjacent the lift opening. A bridge apparatus is also mounted to the support structure in the bridge opening. The bridge apparatus includes a bridge member mounted to the support structure for pivoting between a vertically stored position and a generally horizontal position for extending into the doorway of a light rail vehicle to provide access from the top surface of the pedestal along the bridge to the guideway mounted vehicle. Bridge actuation apparatus is coupled for selectively moving the bridge between the horizontal position and the bridge storage position. Finally, bridge control switches are provided for enabling the bridge actuation apparatus and lift control switches are provided for selectively actuating the lift actuating apparatus.
The present invention may also optionally include a first roll-up door which is mounted in the top region of the housing for being selectively rolled down to a position to cover the lift opening when the lift is in the lift storage position. Also, a second roll-up door is mounted in the top region of the housing for being selectively rolled down to a position covering the bridge opening when the bridge is in the bridge storage position. Motors are provided to effect movement of the first and second roll-up doors with a door control switch provided to selectively actuate the motors.
In yet another embodiment of the invention, the lift apparatus includes a lift disabling mechanism which includes a plurality of platform supports extending a first distance from the bottom of the platform at isolated spaced locations along the bottom of the platform for contacting the landing and supporting the platform against the landing when the platform is in the lowered position. A safety plate is provided a spaced distance below the platform bottom to cover a substantial portion of the surface area of the platform bottom but in non-contacting relationship to the platform supports. The distance the safety plate is spaced below the platform is less than the distance the platform supports extend from the bottom of the platform. Finally, a plurality of switches are attached to the safety plate where each switch is independently responsive to movement of the safety plate toward the platform bottom. Upon such movement, each switch is independently, electrically coupled to disable the lift motor so that movement of the platform immediately stops upon contact with the safety plate.
BRIEF DESCRIPTION OF THE DRAWINGS
A complete understanding of the present invention and of the above and other advantages may be gained from a consideration of the following description of the preferred embodiments taken into conjunction with the accompanying drawings in which:
FIG. 1 is a pictorial view of a lift in accordance with the invention;
FIG. 2 is a back view of the lift apparatus as viewed from the trackway;
FIG. 3 is a side view illustrating the roll-up doors in accordance with the invention;
FIG. 4 is a front view of the lift apparatus;
FIG. 5 is a bottom view of the safety plate apparatus on the bottom of the platform in accordance with the invention;
FIG. 6 is a side view of the lift platform showing additional features of the safety plate apparatus; and
FIG. 7 is a simplified schematic showing one embodiment of the connection of the switches coupled to the safety plate and the motor.
DETAILED DESCRIPTION
Referring initially to FIG. 1, a lift apparatus 10 for providing handicap access from a landing 12 to a vehicle 14, such as a conventional light rail vehicle which moves along trackway 16, includes a support structure 18 consisting of a pedestal 20 and a housing 22. The pedestal 20 may be either permanently fixed to the landing 12 at a predefined distance from and in alignment with the trackway 16 or may be movably mounted in a manner to be described hereafter. The pedestal 20 has a top surface 26 and is preferably made of a heavy material such as concrete to provide a counterbalancing weight to a lift assembly 24. The housing 22 extends upward from the top surface 26 of the pedestal 20 and defines a lift opening 28 on the side of the lift apparatus 10 remote from the trackway and a bridge opening 30 on the other side of the lift apparatus 10 nearest the trackway 16. A passageway 32 extends through the housing 22 between the lift opening 28 and the bridge opening 30. The top surface 26 of the pedestal provides a connecting rampway between the lift opening 28 and the bridge opening 30.
The lift 24 is mounted in the lift opening 28 of the housing 22 and includes a right linkage 34 having an upper end 36 pivotally connected to one side of 38 of the passageway 32. The lift further includes a left linkage 40 which has an upper end 42 similarly connected to the other side 44 of the passageway 32. In the preferred embodiment, the right linkage 34 includes a pair of parallel links 46 connected to a right post 50 and the left linkage 40 includes a pair of parallel links 48 connected to a left post 52. The right post 50 has a lower end 54 which is connected to two one corner of a platform 56. The left post 52 similarly has a lower end 58 pivotally connected to an opposite corner of the platform 56.
The housing 22 also preferably includes a support frame 60 positioned to surround the passageway 32 adjacent the lift opening and to which the right linkage 34 and the left linkage 40 are pivotally attached. In order to prevent the platform 56 from pivoting below a horizontal orientation, a right cable 62 is interconnected between the right post 50 and the platform 56 and a left cable 64 is interconnected between the left post 52 and the platform 56.
Turning to FIG. 4 in connection with FIG. 1, a lift movement means includes a lift motor 66 interconnected to lift chains 70 and 72 which extend over suitable sprockets (not shown), through orifices in the support frame 60, over the top of the posts 50 and 52 to interconnect to the platform 56 adjacent to but spaced slightly outwardly from the lower ends 54 and 58 of the posts 50 and 52 respectively. Thus, when the motor 66 is operated, the chains 62 and 64 either wind or unwind on the sprockets to cause the platform 56 to move between a lowered position adjacent the landing 12 and an upper position which is an extension of the top surface 26 and thereafter to cause the platform to pivot from a horizontal orientation in the upper position to a vertical orientation within the lift opening 28 thereby defining a storage position for the lift 24 when the lift is not in use.
L
One lift device which is particularly adaptable to the present invention is set forth greater detail in U.S Pat. No. Re 31,178, which patent is hereby incorporated by reference.
Finally, the lift 24 includes lift control means 74 for manually causing the platform move between its lowered and its raised positions and further to pivot into the storage position.
In order to provide access from the platform 56 into the guideway mounted vehicle 14, the lift apparatus 10 further includes bridge means 76 mounted in the bridge opening 30 of the housing 22. The bridge means includes a bridge member 78 which is pivotally interconnected to the housing 22 on each side of the passageway 32. The bridge means 76 further includes bridge movement means which, as illustrated, includes a right bridge lifting cable 82 and a left bridge lifting cable 84 interconnected by conventional sprockets and other mechanical linkages (not shown) to a bridge motor (FIG. 4).
Turning to FIGS. 2, 3 and 4, the present invention further includes a first roll-up door 100 mounted in a top region 88 of the housing 22 which may be selectively rolled down to cover the lift opening 28 when the lift 24 is in the vertical storage position within the passageway 32. Similarly, a second roll-up door 102 is mounted in the top region 88 of the housing 22 for being rolled down to cover the bridge opening 30 when the bridge member 78 is pivoted into a vertical position within the passageway 32 of the housing 22. Coupled to cause the first and second roll-up doors 100 and 102 to either cover or uncover the lift opening 28 and bridge opening 30 is a roll-up door movement means or motor 104 interconnected in a conventional manner (not illustrated) to the first and second roll up doors. Electrically coupled to the motor 104 is a door control switch 106. In the preferred embodiment, when the switch 106 is actuated, both the first roll-up door 100 and the second roll-up door 102 are operated simultaneously by the motor means 104. This may be accomplished by suitable gearing of a single motor or by simultaneous electrical actuation of two motors, each connected to one of the first or second roll-up doors 100 or 102. Suitable roll-up doors and their associated control mechanisms are well known and may, for example, be those manufactured and sold under the trademark Alulux.
In order to prevent operation of either the lift 24 or the bridge 76 while the roll-up doors are in the covered or closed position, an interlock means consisting of limit switches 110 mounted at an upper location of the housing 22 and limit switch actuators 112 mounted to the bottom of at least one of the roll-up doors may also be incorporated. The limit switches are positioned so that as the roll-up doors are extended, the limit switch actuators 112 contact the limit switches 110 which may, for example, be coupled in series with both the lift motor 66 and the bridge motor 86, to open the circuit between the motor and their power supplies thereby disabling operation of both motors 66 and 86. When the door is subsequently retracted, the roll-up door switch actuators 112 again contact the switches 110, closing those switches and allowing current to flow from the power supply to the motors 86 and 66. Of course, alternative means of disabling motors 86 and 66 may be incorporated without departing from the present invention.
The present invention further includes bridge control means 114 consisting of a switch which is coupled to actuate the bridge motor 86 to cause the right and left bridge lifting cables 82 and 84 to either extend or retract thereby pivoting the bridge member 78 either from a storage position to a lowered position extending across the light rail vehicle threshold into
the door 90 of the light rail vehicle or pivot upward into a storage position in the bridge opening 30.
Referring momentarily to FIG. 1, in the preferred embodiment the bridge member 78 is pivotally mounted to a support structure 92 which is part of the housing 22 and which extends around the bridge opening 30.
In one embodiment the pedestal 20 is permanently and rigidly affixed to the landing 12. In such an embodiment, it is necessary for the driver of the railed vehicle 14 to align the door of the vehicle 14 with the lift apparatus 10 so that the bridge member 78, when lowered, will extend into a doorway of the railed vehicle. Referring to FIG. 3, the pedestal 20 could alternatively be movably mounted on the landing 12 by providing a suitable track 116 in the landing 12 with suitable wheels or rollers 118 extending from the pedestal 20 to interlock with the track means 116 so that the pedestal is movable along the track means 116 preferably parallel to the trackway 16.
In operation, the lift apparatus 10 on the landing 12 will, prior to use, have the lift 24 folded in a storage position in the passageway 32 and the bridge means 76 likewise folded in a storage position in the passageway 32 with both roll-up doors 100 and 102 in a closed position over the lift opening 28 and bridge opening 30, respectively The rail mounted vehicle which either is to take on or discharge a handicapped person, will approach the lift apparatus 10 aligning one of its doors with the passageway 32 The conductor or other assistant from the railed vehicle will disembark from the door 90 and will actuate the door control switch 106 to raise the first and second roll-up doors 100 and 102 by actuation of the roll-up door movement means 104. When the roll-up doors reach their full opened state, the switch actuator 112 will trip the limit switch 110 enabling operation of the lift motor 66 and the bridge motor 86. The conductor will next actuate the bridge control means 114 which will turn on the bridge motor 86 to lower the bridge member 78 from its stored position to a generally horizontal position extending into the door 90 of the rail mounted vehicle. Once the bridge member 78 is so extended into the doorway 90, the conductor will again mount the vehicle 14 and enter the passageway 32 to operate the lift control means 74.
In the preferred embodiment, the lift control means 74 includes a first manually operated switch 120 and a third manually operated switch 122. Initially, the operator depresses the third manually operated switch 122 which causes the lift apparatus to unfold from a storage position into a horizontal but raised position adjacent the top surface 26 of the pedestal 20. The operator then depresses the first manually operated switch 120 to cause the platform 56 to lower to the landing 12 and assume its lowered position. At that point, a handicapped person in a wheelchair can mount the platform 56 whereupon the lift operator again deflects the first manually operated switch 120 to cause the platform 56 to rise to the upper position adjacent to the top surface 26 whereupon the handicapped person rolls across the top surface 26 onto the bridge and into the vehicle 14. The operator then reverses the above process to again return the lift and bridge to the stored position and lower the first and second roll-up doors 100 and 102.
In one embodiment, a second switch 125 which may be a normally toggle switch may be suitable positioned, for example on the support frame 60, so that when the lift reaches either its lowered or its raised position, the linkage 48 will contact the switch 125 to turn off the lift motor 66. Of course, the switch 125 may be position at any suitable location and is preferably positioned in a protected location.
Turning to FIGS. 5 and 6, an additional detail of the platform 56 is illustrated whereby if a foreign object is inadvertently located underneath the lift platform a safety mechanism will automatically turn off the lift motor when the platform bottom touches the object and hence prevent further movement of the platform until the object between the landing and platform can be removed. This essential safety feature is to prevent the lift from being lowered onto an object which could well be a person To provide such a lift disabling apparatus, the platform in accordance with the present invention includes a support bar 200 extending across the width of the platform at a rear region 202 nearest the pedestal 20 The support bar 200 preferably extends approximately one inch below the bottom surface 204 of the platform 56. Also included are a right front support post 206 and a left front support post 208 which likewise extend approximately one inch from the bottom 204 of the platform 56. The right front support post and left front support post 206 and 208 are positioned near the front region 210 of the platform 56 which is opposite the rear region 202 A safety plate 212 is then provided to cover substantially the entire bottom surface 204 of the platform 56 with the right front support post 206 extending through a right opening 214 in the safety plate 212 and the left front support post 208 extending through a left opening 216 in the safety plate 212. The safety plate 212 is spaced a distance from the platform bottom 204 which is smaller than the distance which the left front support post 208, right front support post 206 and rear support bar 200 extend from the bottom 204 of the platform 56. Hence, the right front support post 206, left front support post 208 and support bar 200 will contact a flat surface such as the landing 12 before the safety plate 212 will contact such landing and hence the safety 212 will not be pressed upward toward the platform 56. In the preferred embodiment, the safety plate 212 is interconnected by four normally closed switches 218, 220, 222 and 224. The switches are mounted to the platform 56 and extend to and are attached to the safety plate 212. In the illustrated embodiment the first switch 218 interconnects and spaces the safety plate 212 a predefined distance from a first corner region 226 of the platform. The second switch 220 is similarly interconnected between the safety plate and the platform at a second corner region 228 adjacent the right front support post 206. The third switch 222 is positioned between the platform and the safety plate at a third corner region 230 adjacent the rear support bar 200 and the fourth switch 224 is mounted between the safety plate 212 and the platform adjacent a fourth corner region 232 adjacent the left front support post 208.
Referring to the simplified representative electrical circuit schematic of FIG. 7, when the platform 56 is lowered in response to actuation of the first manually operable switch 120 (switch 125 is normally closed) and there is an object on the landing underneath the platform, that object will come in contact first with the safety plate 212 in almost all instances. Contact with the safety plate 212 while the platform is still lowering, will cause one or more of the switches 218, 220, 222 and 224 to be opened. As set forth in FIG. 7, the switches may be functionally interconnected in series to the lift motor 66 and are all in a normally closed relationship allowing power from the power supply 240 to operate the lift motor 66. However, when the safety plate is depressed and one of the switches 218, 220, 222 or 224 is depressed then that switch will open and thereby disconnect the power 240 from the motor 66 and immediately causing the platform to stop downward movement.
Of course, various means of electrically interconnecting the switches to operate the lift, bridge and roll up doors are possible and well known to those skilled in the art and have therefore not been described in detail. Also various other embodiments are possible without departing from the present invention as set forth in the claims.
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An apparatus for providing access by a handicapped person from a landing to a guideway mounted vehicle includes a support structure having a pedestal portion and a housing extending upward from the pedestal; a lift, mounted in a lift opening of the support structure, includes a platform, linkages interconnecting the platform to the housing, and movement apparatus coupled to selectively move the platform between a lowered position adjacent a landing, a raised position adjacent the top of the pedestal and a vertical storage position in the lift opening; a bridge member pivots between a horizontal position extending into the doorway of a light rail vehicle and a vertical storage position in the passage adjacent the bridge opening; roll-up doors are mounted in the top region of the housing for being slectively rolled down to a position to cover the lift opening and bridge opening when the lift and bridge are in their respective storage positions. A lift disabling mechanism includes a safety plate spaced distance below the platform bottom in non-contacing relationship to platform supports and a plurality of independently responsive switches attached between the safety plate and the platform bottom. Upon movement of the safety plate relative to the platform, the lift motor is disabled by the switches so that movement of the platform immediately stops.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to the field of injection molding and, more particularly, to an improved method and apparatus for controlling the quantity of a moldable material introduced into the mold cavity by monitoring the area under the part-line separation curve.
2. Description of the Prior Art
The production of consistent and uniform products by the injection molding process has been a long-standing objective in the injection molding art. This objective has become relatively difficult to achieve as more and more injection molding products are produced which are increasingly complex with stricter tolerances. Furthermore, the trend towards fewer and fewer operators monitoring the injection molding processes and apparatus requires more precision automatic control of the process and apparatus.
The injection molding process involves a variety of interrelated parameters present in the injection molding material, apparatus, and control systems. Among these parameters are the type of material being molded, the consistency of the plastic and its characteristics, the molding cycle time, the machine shot size and/or weight, melt viscosity and temperature consistency, mold clamp pressure and injection pressure. As each of these parameters varies during the operation of an injection molding process the product uniformity may suffer without constant operator attention.
Various techniques have been utilized to determine which parameters should be monitored more closely to yield a more consistent molded structure and provide a more reliable injection molding process and apparatus. In the injection molding art, it is necessary to precisely control the amount of moldable material entering the mold cavity during the injection, or filling, phase of the injection molding process.
U.S. Pat. Nos. 2,433,132, 3,976,415 and French Patent No. 2,527,976 teach measuring the part-line separation in the mold elements to determine when to change the molding process from the injection phase to a pulsing of an injection ram to maintain a constant part-line separation during the curing of the mold. However, it has not been feasible to attain high precision accuracy with this technique.
U.S. Pat. Nos. 2,671,247 and 3,859,400 teach monitoring the pressure within the mold itself to determine when to terminate the injection of molding material. However, monitoring pressure alone does not result in a molded product of the desired precision because no compensation is made for variations in other parameters not taken into account U.S. Pat. No. 3,940,465 teaches measuring the part-line separation of the mold to control the cure time of the molding cycle. Similarly, this technique also fails to reflect all of the other variables which must be accommodated and taken into account to accurately control the molded part weight and its dimensions.
U.S. Pat. No. 4,135,873 teaches the measurement of the part-line separation and comparing the separation with a predetermined value and thereafter varying the injection pattern of the injection ram during the following molding cycle. This system does not provide control of the process on a real time basis, reflecting system conditions that are affecting the current cycle. Such a system merely reflects what occurred on the previous cycle, resulting in a tendency for the system to hunt rather than zero into a mode of operation which provides product consistency.
U.S. Pat. No. 4,131,596 teaches the measurement of the part-line separation to reduce the mold clamping pressure upon the measurement of a predetermined separation to minimize any damage to the mold due to flashing of the material at the part-line. This, of course, does not contribute to the control of product weight and dimension.
Japanese Patent Publication No. 11974 of 1978 discloses a method of controlling an injection molding machine wherein the part-line separation is measured and, upon reaching a predetermined reference separation, the machine is switched from a material filling mode to a dwelling mode. The mold separation is then measured and the maximum separation is determined. Thereafter, pressure during the dwell or curing phase of the mold cycle is controlled dependent upon the maximum separation reached to control the final mold separation value at the end of the cure time. Thereafter, the reference separation value for the switch point for the following cycle is changed to accommodate the variations in the machine operation detected during the first cycle. This system of control has the disadvantage that the switch point is determined by the preceding cycle and thus does not reflect the conditions of the current cycle. This system of control thereafter attempts to adapt to the variations in the molding conditions existing during the current cycle by controlling the holding pressure during the cure phase of the cycle which can adversely affect part weight and density uniformity.
U.S. Pat. No. 4,146,601 teaches the method of integrating the hydraulic pressure with respect to time until the cavity pressure reaches a predetermined value. The integrated value is compared with a predetermined value and an adjustment is made in the temperature and viscosity of the material in subsequent molding cycles. This technique is very complicated and information is based upon a prior cycle, not the current injection cycle. As a result, precision and accuracy are compromised.
U.S. Pat. Nos. 4,767,300 and 4,767,519 disclose a method and apparatus for control of an injection molding process based upon the part-line movement of the two faces of the injection mold. Although this system provides a control system which is reasonably effective within a limited range of perturbation in the operating parameters, its effectiveness quickly diminishes as that range is exceeded. This is due primarily to the fact that the relationship between part-line distance and the volume or weight of the moldable material being injected is not linear.
It is apparent from the foregoing that existing control systems tend to be overly complicated, inaccurate and incapable of making same-cycle corrections. Moreover, they generally require almost constant operator attention.
It is therefore an object of this invention to provide a method and an apparatus for precisely controlling the volume of moldable material injected into a mold during a molding process.
It is a further object of the invention to provide a method and an apparatus of the type stated which permits precise control in spite of relatively large perturbations in operating parameters.
It is a further object of this invention to provide a method and an apparatus of the type stated requiring relatively little monitoring by an operator.
Finally, it is an object of this invention to provide a method and an apparatus of the type stated which exercises control over the molding operation on a real time or same-cycle basis. In other words, data gathered and computed during a given molding cycle is used to control that very same cycle rather than subsequent cycles.
SUMMARY OF THE INVENTION
The present invention involves the computation of the area under the curve (sometimes referred to as "AUC" hereinafter) which results when a sequential series of part-line separation measurements is plotted as a function of time during the injection or filling portion of a molding cycle. Interestingly enough, we have found that this area under the curve (AUC) bears a direct relationship with the volume of moldable material being delivered to the mold even though operating parameters such as injection pressure may vary from their normal settings within normally expected ranges. Thus, once an optimum value for the area under the curve is experimentally determined, it becomes possible to correlate that value with the desired volume of moldable material and the resulting part weight of the object being molded. Part weight is, of course, one of the primary indicia of part quality.
The improved method of this invention may be used with a molding machine of the type having a pair of separable mold elements and, further, having the capability of injecting moldable material therein at a first pressure and holding said material therein during curing at a second pressure. The method comprises the steps of closing the mold elements, introducing moldable material into the mold cavity at a first pressure and periodically measuring the separation of the mold elements while moldable material is being introduced into the cavity. Also, the method includes integrating, as a function of time, the part-line separation distance while the moldable material is being introduced into the cavity, detecting when the integral reaches a preselected value and changing the pressure from the first pressure to the second when the integral reaches the preselected value. Finally, opening the mold elements occurs when the moldable material has cured.
The method may also include continuing the measuring and integrating steps after the pressure has been changed and until the mold elements cease separating, comparing the integral value to a further preselected value and generating a signal indicative that the molded product is defective if the integral does not substantially correspond to the further preselected value. The method may include activating an alarm signal which may also stop the molding cycle and opening the mold elements and/or activating a later reject/sort device.
The method may also include determining the time in the molding cycle at which the first preselected value is reached and generating a signal that the molded product is defective if the time falls outside a predetermined acceptable range. Again, the signal could be used to stop the molding cycle and open the mold elements and/or to activate a later reject/sort device.
The invention also provides for an improved molding apparatus having a pair of separable mold elements forming a mold cavity therebetween, means for opening and closing the mold elements, means for introducing a moldable material into the mold cavity at a first pressure and for exerting a second pressure on the moldable material, means for measuring and integrating the separation distance of the mold elements as a function of time as the mold elements separate while the moldable material is being introduced into the mold cavity, means for detecting when the integral value reaches a preselected value and for then changing from the first pressure to the second pressure.
The apparatus may also include means for continuing the measuring and integrating functions after changing the pressure and until the mold elements cease separating, means for comparing the resulting integral value to a second preselected value, and means for generating a signal indicative that the molded product is defective based upon the value of the integral when separation ceases. The apparatus may also include an alarm responsive to the signal, means responsive to the signal for stopping the cycle and opening the mold elements and/or a means for activating a later reject/sort device.
Also, the apparatus may include means for determining the time in the molding cycle at which the first preselected value is reached and for generating a signal that the molded product is defective if the time falls outside a predetermined range. The signal generated by the apparatus may operate an alarm, stop the molding cycle and open the mold elements and/or activate a later reject or sort device.
The present invention contains certain advantages over the prior techniques of volumetric control of an injection molding process. The linear relationship of the AUC to the product weight provides a definite improvement in the control of the volume compared to conventional techniques. The part weight can be controlled over a far wider range of external error sources and sorting of the molded product may be more accurately performed because the desired product characteristics are more precisely achieved through monitoring and control of the AUC. Furthermore, we have found that when using an AUC control strategy as described hereinafter, errors due to machine "skidding" are reduced. Also, the AUC control technique provides far superior compensation for changes in the dynamic response of the molding machine components as compared with other control strategies.
Various means for practicing the invention and other features and advantages thereof will be apparent from the following detailed description of the illustrative preferred embodiments of the invention, reference being made to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of an injection molding apparatus in accordance with the present invention;
FIG. 2 is an enlarged view of the distance sensor and target as mounted on the mold elements for sensing the part-line separation;
FIGS. 3, 3a are a graphic illustration of a sample part-line curve representing the separation distance of the mold elements as a function of time;
FIGS. 4--1 to 4--3 depict a flow chart representing the steps performed by the controller of FIG. 1 in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
One form of an injection molding apparatus 10 is illustrated in FIG. 1 and comprises a pair of pressure platens 12 and 14 arranged to carry a pair of mold elements 16 and 18, respectively. The mold elements are arranged to meet at a part-line 20 and form a mold cavity 22 therebetween, all in a manner well known in the art. Platen 12 and the mold element 16 associated therewith are stationarily arranged on the machine while platen 14 and mold element 18 associated therewith are movably arranged to be displaced along tie bars 24 and 26 between an open and closed position by a hydraulic cylinder 28.
A plastic extruder assembly 30 is arranged to engage a gate 32 in the mold element 16 with an injection nozzle 34 at the outlet end of the extruder. The main portion of the extruder comprises an extruder barrel 36 having a rotating plasticating screw 38 therein which receives particulate material from a supply 40, and via heat and manipulation plasticates the material for injection through nozzle 34 into the mold cavity 22. To aid in the plastication of the material the extruder barrel is provided with encasing heater elements 42 and 44, in a manner well known in the art. The screw is rotated by a gear 46 driven by a motor, not shown, and is driven longitudinally to inject the molten material into the mold cavity by means of a hydraulic cylinder 48. The hydraulic cylinder 48 is provided with hydraulic fluid from a power source in order to drive the screw longitudinally during the injection process. The hydraulic fluid supply provides both a high pressure for the injection phase of the cycle as well as a low pressure for the holding phase of the cycle, as is well known in the art. One example of such a hydraulic supply comprises separate sources of high injection pressure 50 and lower holding pressure 52 connected by lines 54 and 56 to a control valve 58 which determines which pressure is supplied by line 60 to the hydraulic cylinder 48.
While a reciprocating screw injection molding machine is illustrated for the purposes of describing the present invention, it will be appreciated by those skilled in the art that other forms of injection molding machines such as plunger and transfer-compression molding machines may also be employed.
A distance sensor 62 is mounted on the stationary mold element 16 adjacent part-line 20. A distance sensor target 64 is mounted on the movable mold element 18 is opposition to the sensor 62 as shown in FIG. 2. The target may comprises an adjustable bolt or pin member 66 which is arranged to provide the target for sensor 62. The sensor and target are arranged to come into close proximity when the mold elements are closed and clamped but are carefully positioned so that at no time do they contact one another. The sensor element 62 may be of any type know in the art including capacitive, inductive, optical, or other type proximity sensor having a substantially linear output over a range from +10 volts to -10 volts representing a distance range of 0.020 inches.
As shown in FIG. 2, the proximity sensor 62 provides an analog output signal via line 68 to a central processing unit, or controller 70, the operation of which will be described herein below. The controller 70 is arranged to provide an output signal via line 72 to actuate a portion of the molding apparatus, such as a valve actuator 74, which is connected to valve 58. Thus, depending upon data received from sensor 62, controller 70 provides an appropriate output to valve actuator 74 to switch the valve 58 from the high injection pressure 50 to the lower holding pressure 52, or vice versa, to thereby control the cycle of the injection molding machine in accordance with the present invention.
It has been found that when an injection molding machine is operated with a sensor sufficiently sensitive to accurately measure the part-line separation between the mold elements 16 and 18, that a characteristic time/displacement (separation) curve is generated for that machine. It has also been found that the integral of the part-line separation dimension represented by this curve or the area under the time/displacement curve bears a substantially direct, linear relationship to the part weight, and hence, the volume of moldable material being injected into the mold cavity, regardless of normally occurring perturbations in operating parameters and variations in machine characteristics affecting the molding cycle.
One example of such a time/displacement curve is illustrated in FIG. 3 and will be referred to in the following description of the operation of the present invention in conjunction with the logic chart illustrated in FIG. 4--1 to 4--3. The curve represents the variation of the part-line separation with respect to time during a single molding cycle of an injection molding machine operating at a steady state condition after stabilization following start-up. As the empty mold elements begin to close, the part-line sensor will start to indicate the part-line separation as the mold elements approach each other. As the mold elements approach a predetermined separation S 1 , which is designated the Entry Threshold, a separation of 0.0095 inches, for example, the high pressure clamp system on the injection molding press is disabled, actuating the low-pressure protection portion of the system. As is well known to those skilled in the art, the purpose for operating the system in this manner is to guard against the possibility that high pressure clamping force will be applied before the system confirms that the last made part has been successfully ejected from the mold. As the Entry Threshold is crossed by the continued closing of the mold elements a master counter/timer within controller 70 is actuated at T 1 and a "bad part sort" output signal, which may have been activated from the previous cycle, is disabled or turned off.
As the mold elements continue to close, the part-line separation reaches a "low pressure protection clamp" separation point S 2 and the machine high-pressure clamping of the mold is activated so that the molten plastic material may be injected into the mold cavity. Thereafter, the master timer reaches the mold closed control delay timer point T 7 , and the part-line separation sensor is read to determine the actual measurement of part-line separation which may be sensed after final closing and clamping of the mold elements at S 3 . After it is determined that the mold elements have been clamped together, the injection of the molten material into the mold cavity is initiated with the injection ram 48 operating under the high injection pressure 50. As the mold fills the part-line separation value decreases slightly to a minimum value S 5 at T 5 which may be 0.005 inches for example. When a minimum separation has been reached the controller 70 stores this value as a reference value and begins to calculate the area under the curve. The area under the curve is calculated by controller 70. This is accomplished by frequently reading the part-line value, subtracting the minimum value stored at T 5 and adding the difference to the existing AUC value. This operation is illustrated in FIG. 4--2.
Also, we have found that with the use of AUC control, the transfer point at which the system switches from high pressure to low pressure will occur within a reasonably predictable time. Furthermore, if this transfer point is not reached within that time, the part weight will exceed specification. It is therefore possible to establish a suitable window of time within which the transfer point will occur for an acceptable product. Controller 70 can therefore be appropriately programmed to initiate a window timer near the beginning of the part-line sampling process. If the transition point is not reached before the window time is timed out, then an appropriate signal can be generated for an alarm and/or sorting out of the part in question as a bad part. The window timer steps are likewise illustrated in FIG. 4--3. When the mold begins to fill to capacity the mold elements begin to separate along the part-line as shown in the position of the curve after T 5 . When the AUC reaches a predetermined area under the curve set point value, e.g. control point S 4 at T 4 , a control signal is delivered by the controller to the valve operator 74, switching valve 58 from the high injection pressure 50 to the lower holding pressure 52. Thereafter, because of the finite lag in the signal activating the valve 58 and the injection ram responding to the change in pressure, as well as other inertial or "skidding" effects in the operation of the machine, the part-line separation will continue to increase until it reaches a maximum S 6 . At that point the material in the mold will begin to cool and shrink and the part-line separation will fall back to approximately the initial mold closed separation S 3 during the curing or cooling phase of the molding cycle.
The controller may be programmed to continue to calculate the AUC up to this point. Once the material being molded has cured, the mold will be opened and the part ejected and the sensor will indicate that the part-line separation, has exceeded the Exit Threshold S 8 . When the maximum part-line separation value S 6 is detected and measured, the AUC may again be calculated. This value can be compared with a preselected standard value to determine if the molded product meets specifications.
As noted above, the area under the curve is calculated by subtracting the mold closed minimum separation value S 5 from the currently measured part-line separation value. Since the minimum separation value is determined for every cycle, variations in the performance of the machine are accommodated.
The molding process is initiated after the sensor has been installed in the molding machine and the controller wired to the appropriate controlling portion of the machine. The injection molding machine is then operated and the operating parameters such as injection pressure and clamping force are adjusted until the machine produces acceptable parts. During this operation the controller is set to the "monitor mode" whereby part-line separations and the corresponding area's under the curve are measured and monitored with appropriate data being retained in the controller memory. Appropriate adjustments are made to the process by the machine operator to achieve satisfactory molded parts. As the satisfactory parts are identified, the AUC measurements made for those satisfactory parts are utilized to determine the desired predetermined AUC set point, low pressure protection point value and control offset, as well as the minimum part-line separations to be used for controlling the process. At the same time, the appropriate control delay times are also being selected by the operator according to the particular characteristics of that individual machine. As soon as sufficient data has been collected to ensure the operator that the sampling is representative, and the values have been set into the controller, the controller may be switched to the "control mode" wherein it commences the control of the injection molding process.
Using AUC control methods, as described above, the part weight consistency of the machine output is significantly improved, as compared with known control methods. As a result, the average size of the product can be slightly reduced since the assurance of consistency and repeatability of part size and weight provided by the present invention allows for the reduction of mean-part weight. The operator need now only use that amount of raw material required to achieve the smallest statistically acceptable product resulting in a material savings while still remaining above the minimum part weight determined for the uncontrolled operation of the machine.
Various timers within the present system allow an operator to select the appropriate interval at which to perform a function appropriate to that particular machine. The timers may activate blanking signals to limit the reading of the part-line separation sensor and/or area under the curve to the appropriate window period in the cycle. Thus, any vibration or jitter present in the machine that occurs during the blanked portions will not provide spurious part-line separation signals that could adversely affect the overall machine control. For example, as shown in FIG. 3 calculation of the area under the curve will begin at control delay time T 7 and end at window time T 9 . Moreover, as noted above, the timing offset T 9 , or some other predetermined time, may act as a maximum time to reach the area under the curve set point value; if the set point value is not reached within the offset time T 9 then a signal is generated and/or the system may be reset.
Accordingly, the present invention provides a method and apparatus for controlling an injection machine and process by using the integral of, or area under, the part-line separation curve of the mold elements as a verification of achieving product quality. The control and measurement of the area under the curve assures part completion, uniformity and quality. The present invention provides an improved verification technique such that the variable parameters in the molding machine and process are combined to achieve the specified part. Because of the improved product quality provided by the present invention, substantial reductions in part rejects are achieved. This results in improved costs by minimizing the amount of material regrind necessary as well as the improved quality raw material from reduced regrind. With a reduction in rejects also comes a reduction in labor. Still further, older molding machines are capable of producing higher quality products with reduced labor and increased flexibility permitted by frequent mold and process changes while still providing the requisite product quality.
While the invention has been particularly shown and described with respect the certain preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.
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An improved technique for use with a molding apparatus having a pair of separable mold elements and forming a mold cavity therebetween which includes a means for opening and closing the mold elements and a means for introducing a moldable material into the mold cavity at a first pressure and for exerting a second pressure on the moldable material as it cures in the cavity has been developed. The technique involves measuring the separating distance of the mold elements while the moldable material is being introduced into the cavity and integrating the separation distance as a function of time. When the integral value reaches a preselected value, the mold injection pressure is changed and the moldable material is allowed to cure within the cavity.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brushless direct current motors, and in particular, to the stator coil driver circuitry for the brushless direct current motor, and still more particularly to a slew rate control circuit for the driver circuit.
2. Technical Background
Brushless direct current motors (DC motors) are commonly used in disk drives, tape drives, video cassette players, and the like and are typically under stringent requirements regarding their performance in these applications. During the phase commutation of such a motor, which is achieved by switching off the current in one stator coil while at the same time switching on the current in another coil, current ripple has been a problem. It is known in the art that the commutation should be performed when the back electromotive force (BEMF) on the two coils is equal and the torque provided by each coil is also equal. Torque ripple has been a problem during commutation which results in undesirable acoustical noise produced by the motor and unnecessary wear on the motor.
FIG. 1 illustrates the typical architecture of a brushless DC motor as is known in the art. This architecture includes a motor 12, a commutator 20, a driver 22, and a voltage supply 24. The motor includes a rotor 14, a stator 16, and hall effect sensors 103. (Although this block diagram shows hall effect sensors, it is also known in the art to use the BEMF of a floating coil to determine the position of the rotor instead of using hall effect sensors.) The stator 16 includes stator coils 26a, 26b, and 26c configured in a wye configuration. In operation, the commutator block 20 sequentially selects the appropriate stator coil driver circuit in driver block 22 to drive current into or out of stator coils 16a, 16b, or 16c, as is known in the art. Hall effect sensors 103, in combination with rotor 14, provide the position information necessary so that the commutator circuit 20 can commutate the driver circuit 22 at the appropriate time. The operation of a typical disk drive is more fully described in U.S. Pat. Nos. 5,017,845, 5,172,036, 5,191,269, 5,221,881, and 5,306,988, and are fully incorporated into this specification by reference.
FIG. 2 shows a prior art circuit, which is described in detail in U.S. Pat. No. 5,191,269, used to reduce commutation ripple. This circuit reduces commutation ripple by using a combination of voltage slew-rate control on the phase which is turning off and a fast closing of the current loop through the phase which is turning on. More specifically, FIG. 2 shows stator coils 26a, 26b, and 26c in a wye configuration. A low side driver circuit for stator coil 26a is shown as including switch 56, current source 72, amplifier 70, capacitor 76, transistor 38. A low side driver circuit for stator coil 26b is shown as including switch 62, current source 84, amplifier 82, capacitor 88, transistor 44.
In FIG. 2, stator coil 26a is being turned off while stator coil 26b is being turned on. Upon the commutator causing the first switch 56 to open while causing the second switch 62 to close, the slew-rate control controls the rate of turn-off of the current flowing in the one phase while the current sensing resistor senses the sum of the current flowing in transistors 38 and 44. The current sensing resistor imposes a feedback voltage indicative of the summed current of transistors 38 and 44 at the inverting input of the operational amplifier 50. The operational amplifier 50 produces a voltage at the output representative of the voltage difference between the predetermined voltage of the voltage source and the feedback voltage, whereby the voltage difference at the gate of the second transistor controls the rate of turn-on of the other phase so that the total current in the phase is maintained constant through the commutation and is equal to Vin divided by the resistance of the sensing resistor 30.
The drawbacks to this approach are:
1. The technique does not work in pulse width modulation (PWM) mode since the slew-rate control is killed by the PWM operation, thus preventing a smooth current transition.
2. The fast turn-on of the phase controlling the current generates EMI, unless some circuitry is added to control turn-on slew-rate, potentially at the expense of current stability.
3. The circuit requires some extra circuitry to minimize delays when the commutations are effected from a "saturated" condition (i.e. gate overdrive) which is typically used when a series device is controlling the current such is in high power applications.
4. The overall predriver circuitry is rather complicated, partially because of all the above patches.
SUMMARY OF THE INVENTION
Therefore, it is an object of the invention to simplify the predriver circuitry.
It is another object of the invention to reduce EMI and acoustical noise in both linear and PWM modes.
It is yet another object of the invention to improve stability due to the absence of local feedback for slew rate control.
It is yet another object of the invention to be compatible with both low-side driver regulation and series pass regulation.
These and other objects, features, and advantages of the invention will be apparent to those skilled in the art from the following detailed description of the invention, when read with the drawing and pended claims.
In accordance with a broad aspect of the invention, a circuit to drive the stator coils of a polyphase DC motor is improved by including slew rate control circuitry to the driver circuitry. The slew rate control circuitry includes a capacitor, a current source for charging the capacitor, and a current source for discharging the capacitor. By using the slew rate control circuitry in combination with a sense resistor and operational transconductance amplifier feedback loop, constant current can be maintained in the coils during commutation which reduces torque ripple and EMI. The disclosed technique is effective in linear mode as well as in PWM mode.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block diagram of a conventional DC motor control circuit.
FIG. 2 is a schematic diagram of a prior art driver circuit.
FIG. 3 is a schematic diagram of the preferred embodiment of a driver circuit, including a driver circuit.
FIG. 4 is a timing diagram of the input signals to FIG. 3 and the current wave forms for stator coils 26a and 26b.
FIG. 5 is a schematic diagram of an embodiment of a driver circuit using a sensefet (current mirror) in the place of a sense resistor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A stator coil driver circuit constructed according to the preferred embodiment of the invention will be described. Referring now to FIG. 3, the stator coils 26a, 26b, and 26c are connected in a wye configuration. The driver circuit 80a for coil 26a is the same as the driver circuit 80b for coil 26b, as shown. Additionally, it is understood that typically three drive circuits would be preferable for driving three coils in a wye configuration.
The driver circuit for coil 26a includes inverter 100, which has an input for receiving a coil A control logic signal from commutator 20 and an output which is connected to the control element of current source 102. Current source 102 has a draining end connected to a supply voltage, Vdd, and a sourcing end connected to a draining end of current source 104, a first plate of capacitor 106, and a gate of N-channel MOSFET transistor 108. Current source 104 has a control element connected to the input of inverter 100 and has a source end connected to a voltage reference, ground. The second plate of capacitor 106 is connected to ground. Transistor 108 has a drain connected to a current mirror which is made up from P-channel MOSFET transistor 112 and P-channel MOSFET transistor 114. The source of transistor 108 is connected to a first end of resistor 110. The drain of transistor 108 is connected to the drain and gate of transistor 112 and the gate of transistor 114. The source of transistor 112 and 114 are connected to Vdd. The drain of transistor 114 is connected to the drain and gate of n-channel MOSFET transistor 116 and the input of unity gain buffer amplifier 117. The output of unity gain amplifier 117 is connected to the gate of n-channel MOSFET transistor 118. Transistor 116, buffer amplifier 117, and transistor 118 form the second current mirror where the buffer amplifier 117 improves the performance of the current mirror. The drain of transistor 118 is connected to the source of n-channel MOSFET transistor 120 and to one end of coil 26a. Transistor 120 is the high side driver transistor and transistor 118 is the low side driver for coil 26a. The highside drive is shown as unconnected although it is understood in the art that its gate would be connected to high side driver circuitry, as is known in the art. The sources of transistor 116 and 118 are connected to the first end of sense resistor 130, as is a similar transistor in driver circuit 80b. The second end of sense resistor 130 is connected to ground.
The driver circuit for coil 26b is constructed in an analogous manner as the driver circuit for coil 26a. The elements which function in the same manner are labeled with the same identification number, but additionally have a "b" added at the end of its number to designate that the element is for the coil 26b driver circuit. The coil 26b circuit is included to illustrate the interaction between coil 26a and coil 26b when a commutation occurs. It is understood by persons skilled in the art that a third driver circuit for coil 26c would typically also be included in a motor with a three coil stator Configured in a wye configuration.
The coil 26b driver circuit is constructed with inverter 100b having an input for receiving the Coil B control logic signal and having an output connected to the control element of current source 102b. The drain of current source 102b is connected to Vdd and the source of current source 102b is connected to the drain of current source 104b, the first plate of capacitor 106b, and the gate of N-channel MOSFET transistor 108b. The control element of 104b is connected to the input of inverter 100b. The second plate of capacitor 106b is connected to ground. The drain of transistor 108b is connected to the drain and gate of P-channel MOSFET transistor 112b and the gate of P-channel MOSFET transistor 114b. The sources of transistors 112b and 114b are connected to Vdd. Transistor 112b and 114b form the first current mirror. The drain of transistor 114b is connected to the drain and gate of n-channel MOSFET transistor 116b and the input of unity gain buffer amplifier 117b. The output of amplifier 117b is connected to the gate of n-channel MOSFET transistor 118b. Transistor 116b, unity gain buffer amplifier, and transistor 118b form the second current mirror where the unity gain amplifier improves the performance of the current mirror. The sources of transistors 116b and 118b are connected to the first end of sense resistor 130. The drain of transistor 118b is connected to the first end of coil 206b. Transistor 120b is the high side driver for coil 26b and is shown with its drain connected to Vdd and its source connected to the first end of coil 26b.
The first end of sense resistor 130 is connected to the inverting input of operational transconductance amplifier 132 (OTA 132). The non-inverting input of OTA 132 receives a V in signal. The output of OTA 132 is connected to the second end of resistor 110 in drive circuit 80a and the second end of resistor 110b in drive circuit 80b.
In steady state operation, the current through a given coil is controlled by the V in signal in combination with the coil A, coil B, and coil C signals. For example, in a phase in which coil 26a is driven, the coil A signal turns on current source 102 to charge capacitor 106 such that transistor 108 is in the on state. Therefore, the current flowing through transistor 108 will be controlled by OTA 132 responsive to the V in signal and the feedback voltage from the sense resistor 130. The current through transistor 108 controls the current through the first current mirror, of transistors 112 and 114, which, in turn, controls the second current mirror of transistors 116 and 118, thus the current through the low-side driver transistor 118. While coil 26a is in the steady on state, coil 26b would be turned off by coil B signal, with current source 102b off and current source 104b on. In this state, any charge on capacitor 106b would be discharged by current source 104b. Consequently, transistor 108b is held in the off state since the voltage on capacitor 106b is held low by current source 104b. Therefore, the first current mirror made up of transistor 112b and 114b are in the off state which in turn keep transistors 116b and 118b turned off.
FIG. 4 illustrates the relative signal timing for the Coil A control logic signal and the Coil B control logic signal when the two phases are commutating. The Coil A control logic signal shows coil 26a being turned on and then being turned off. The Coil B control logic signal shows coil 26b being turned on at the precise time that the coil 26a signal is being turned off. The resulting Current A wave form shows the current ramping down from a steady state value to zero as Coil A has been turned off. At the same time, the Current B waveform shows the current in the 26b coil ramping from a zero current to a steady state current at the same, but opposite, rate as the current a waveform is going from the steady state value to zero.
During commutation, the control logic signal Coil A is going from high to low while the control logic signal Coil B is going from low to high. Therefore, current source 102 is being turned off while current source 104 is being turned on at the same time that current source 102b is being turned on and current source 104b is being turned off. The charge on capacitor 106 is going from a full charge to a zero charge at the same time the charge on capacitor 106b is going from no charge to a full charge. As a consequence, the current through coil 26a ramps down from its steady state value to zero at the same time that the current through coil 26b ramps up to a steady state value. The steady state value is ultimately controlled by OTA 132 and V in signal, as explained earlier. Therefore, the commutation is controlled in a manner such that the total current in coil 26a and 26b remains substantially constant. Consequently, noise due to the commutation is reduced in both linear and PWM modes. Stability is also increased due to the absence of local feedback for the slew rate control. This invention is compatible with both low-side driver regulation as well as series pass regulation.
FIG. 5 shows an alternative embodiment where the sense resistor of FIG. 3 is replaced with sensefet (current mirror) circuitry. More specifically, the alternative embodiment in FIG. 5 is constructed with inverter 100 having an input and having an output connected to the control element of current source 102. The drain of current source 102 is connected to Vdd while the source of current source 102 is connected to the drain of current source 104, the first plate of capacitor 106, and the gate of N-channel MOSFET transistor 108. The control element of current source 104 is connected to the input of inverter 100 and the source of current source 104 is connected to ground. The second plate of capacitor 106 is connected to ground. The drain of transistor 108 is connected to the drain and gate of P-channel MOSFET transistor 112 and the gate of P-channel MOSFET transistor 114. The sources of transistors 112 and 114 are connected to Vdd. Transistor 112 and 114 make up the first current mirror of the circuit. The drain of transistor 114 is connected to the drain and gate of N-channel MOSFET transistor 116 and the input of amplifier 117. The output of amplifier 117 is connected to the gate of N-channel MOSFET transistor 118. Transistor 116 and 118 make up the second current mirror of the circuit. N-channel transistor 120 is the high side driver for coil 26a.
The sensefet circuit includes transistor 122 which has its gate connected to transistor 118. The drain of transistor 122 is connected to the inverting input of amplifier 124, the non-inverting input is connected to the drain of transistor 118. The output of amplifier 124 is connected to the gate of N-channel MOSFET transistor 126. The drain of transistor 126 is connected to a current mirror composed of transistors 136 and 128. The source of transistor 128 is connected to Vdd and the drain of transistor 128 is connected to the inverting input of OTA 132 and resistor 138.
Transistor 122, amplifier 124, transistor 126, and transistor 128 operate to provide a voltage to OTA 132 which is proportional to the current through transistor 118. Therefore, the sensefet (current mirror) circuit take the place of the sense resistor 130 in FIG. 3. This circuit also offers the advantages of the commutation being controlled in a manner such that the total current in coil 26a and 26b remains a constant. Consequently, noise due to the commutation is reduced in both linear and PWM modes. Stability is also increased due to the absence of local feedback for the slew rate control.
Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the combination and arrangement of parts can be resorted to by those skilled in the art without departing from the spirit and scope of the invention, as hereinafter claimed.
Also, bipolar transistors may replace MOS devices at will.
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A stator coil driver circuit for a brushless DC motor, which minimizes torque ripple by keeping the current in the commutating phases constant, is disclosed. The circuit includes a slew rate control circuit for ramping up the current or ramping down the current during commutation. The slew rate control circuit consists of a capacitor, a first current source for charging the capacitor, and a second current source for discharging the capacitor. The circuit also includes a sense resistor or a sensefet and an operational transconductance amplifier for providing feedback control.
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BACKGROUND OF THE INVENTION
This invention relates to a separation system and process as illustrated in FIG. 1 useful for the product produced by Armstrong method as disclosed and claimed in U.S. Pat. Nos. 5,779,761; 5,958,106 and 6,409,797, the disclosures of each and every one of the above-captioned patents are incorporated by reference.
SUMMARY OF THE INVENTION
A principal object of the invention is to provide a separation system for the Armstrong process disclosed in the '761, '106 and '797 patents;
Another object of the invention is to provide a continuous separation system.
The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of the separation system of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The system 10 of the present invention deals with the separation of a metal, alloy or ceramic product, such as titanium, for example only, from the reaction products in the Armstrong process. Although the Armstrong process is applicable to a wide variety of exothermic reactions, it is principally applicable to metals, mixtures, alloys and ceramics disclosed in the above-mentioned patents. The product of Armstrong process is a slurry of excess reductant metal, product metal and alloy or ceramic and salt produced from the reaction. This slurry has to be separated so that various parts of it can be recycled and the produced metal, alloy or ceramic separated and passivated if necessary.
Turning now to the schematic illustration of the system and process of the present invention illustrated in FIG. 1 , there is disclosed in the system 10 a source of, for illustration purposes only, titanium tetrachloride 12 which is introduced into a reactor 15 of the type hereinbefore disclosed in the Armstrong process. A supply tank or reservoir 17 with a supply of sodium (or other reductant) 18 is transferred by a pump 19 to the reactor 15 wherein a slurry product 20 of excess reductant and metal, alloy or ceramic, and salt is produced at an elevated temperature, all as previously described in the incorporated patents.
The slurry product 20 is transferred to a vessel 25 which is in the illustration dome-shaped, but not necessarily of that configuration, the vessel 25 having an interior 26 into which the slurry product 20 is introduced. A filter 27 , preferably but not necessarily cylindrical, is positioned within the interior 26 and defines an annulus 28 , the slurry product 20 being received inside the cylindrical filter 27 . An annular heat exchanger 29 is positioned around the vessel 25 , all for a purpose hereinafter disclosed.
The vessel 25 further includes a moveable bottom closure 30 . Heat exchange plates 32 are connected as will hereinafter be described to an isolated heating system 50 . A collection vessel 35 is positioned below the vessel 25 and is sealed therefrom by the moveable bottom closure 30 . The collection vessel 35 has an inwardly sloping bottom surface 36 which leads to a crusher 38 and a valve 39 in the outlet 40 of the collection vessel 35 .
Finally, a vapor conduit 42 interconnects the top of the vessel 25 and particularly the interior 26 thereof with a condenser vessel 45 , the condenser vessel having a heat exchange plate 46 connected, as hereinafter described, to an isolated cooling system 60 . The condenser 45 is connected to a condenser reservoir 49 , the condensate collected therein being routed to the sodium supply tank or reservoir 17 .
The isolated heating system 50 includes a head tank 52 for the heating fluid which is moved by pump 53 to the heater 55 as will be hereinafter described, connected to both the heat exchanger 29 surrounding the vessel 25 and the heat exchange plates 32 interior of the vessel 25 . The isolating cooling system 60 also is provided with a head tank 62 , a pump 63 and a cooler 65 which serves to cool the cooling fluid circulated in an isolated loop to the cooling plates 46 as will be hereinafter set forth.
Below the valve 39 and the collection vessel 35 is a product conveyor 70 having a baffle or cake spreader 71 extending downwardly toward the conveyor 70 . The conveyor 70 onto which the produced metal, alloy or ceramic and salt are introduced from the collection vessel 35 , after removal of the excess reductant metal, is contacted with a counter current flow of gas, preferably but not necessarily oxygen and argon, 77 from a blower 75 in communication with a supply 76 of oxygen and the supply of inert gas such as argon. The heat exchanger 79 is in communication with the blower 75 so as to cool the oxygen/argon mixture 77 as it flows in counter current relationship with the produced metal, alloy or ceramic on the conveyor 70 , thereby to contact the product particulates with oxygen to inertthe produced metal, alloy or ceramic when required but not so much as to contaminate the produced material.
As indicated in the flow sheet of FIG. 1 , there are a plurality of flow meters 81 distributed throughout the system, as required and as well known in the engineering art. There are pressure transducers 86 and pressure control valves 89 where required, all within the engineering skill of the art. A back filter valve 91 is provided in order to flush the filter 27 if necessary. Additionally, a variety of standard shut-off valves 93 are positioned within the loop, hereinafter to be explained and as required. A vacuum pump 95 is used to draw a vacuum in the vessel 25 , as will be explained, and the symbol indicated by reference numeral 100 indicates that a plurality of the same or similar systems may be operating at any one time, it being remembered that the enclosed figure is for a single reactor 15 and one separation vessel 25 , wherein as in a commercial production plant, a plurality of reactors 15 may be operating simultaneously each reactor 15 may have more than one separation vessel 25 , all depending on engineering economics and ordinary scale up issues.
Product 20 from the reactor 15 exits through line 110 and enters vessel 25 at the top thereof. Although line 110 is shown entering above the filter 27 , preferably the line 110 and filter 27 are positioned so that slurry 20 is introduced below the top of filter 27 or in the center of the filter or both. As described in the previously incorporated patents, the slurry product 20 consists of excess reductant metal, salt formed by the reaction and the product of the reaction which in this specific example is titanium existing as solid particles. The product 20 in slurry form from the reactor 15 is at an elevated temperature depending on the amount of excess reductant metal present, the heat capacity thereof and other factors in the reactor 15 during operation of the Armstrong process. In the vessel 25 is a filter 27 which occupies a portion of the interior 26 of the vessel 25 , the interior optionally being heated with the annular heat exchanger 29 . The slurry product 20 is directed to the interior of the filter 27 where the slurry contacts the heat exchange plates 32 .
In the heating system 50 , the heat exchange fluid in the plates 32 pass with the heat exchange fluid from the annular heat exchanger 29 through line 111 to the line 112 which connects the heat exchange medium supply in the head tank 52 to the heat exchanger 55 . Fluid moves from the heater 55 through the heat exchange plates 32 by means of the pump 53 as the heated heat exchange fluid flows out of the heat exchanger 55 through line 113 and back into the heat exchange plates 32 and/or the annular heat exchanger 29 . Because the heating system 50 is a closed loop, the heat exchange fluid may or may not be the same as the reductant metal used in the reactor 15 . NaK is shown as an example because of the low melting point thereof, but any other suitable heat exchange fluid may be used. Suitable valves 93 control the flow of heat exchange fluid from the heater 55 to either or both of the heat exchanger 29 and plates 32 . Preferably, the plates 32 are relatively close together, on the order of a few inches, to provide more heat to the cake which forms as excess reductant metal vaporizes. Moreover, closer plates 32 reduce the path length the heat has to travel and the path length the excess reductant metal vapor travels through the forming cake, thereby to reduce the time required to distill and remove excess reductant metal from the vessel 25 . Exact spacing of the plates 32 depends on a number of factors, including but not limited to, the total surface area of the plates, the heat transfer coefficient of the plates, the amount of reductant metal to be vaporized and the temperature differential between the inside and the outside of the plates.
When the slurry product 20 comes out of the reactor 15 , it is at a pressure at which the reactor 15 is operated, usually up to about two atmospheres. The product slurry 20 enters the inside of filter 27 under elevated pressure and gravity results in the liquid reductant metal being expressed through the filter 27 into the annular space 28 and fed by the line 120 into the reservoir 17 . The driving force for this portion of the separation is gravity and the pressure differential between the reactor 15 and the inlet pressure of pump 19 . If required the annulus 28 may be operated under vacuum to assist removal of liquid reductant metal, or the pressure in vessel 25 may be increased during the deliquoring of the reductant metal. After sufficient liquid metal has drained through the filter 27 by the aforementioned process, the PCV valve 89 is closed and other valves 93 are closed to isolate vessel 25 and then the valve 93 to the vacuum pump 95 is opened, whereupon a vacuum is established in the interior 26 of vessel 25 . Heating fluid (liquid or vapor, for instance Na vapor) is directed into the heat exchanger plates 32 to boil the remaining reductant metal 18 producing a filter cake. The temperature in vessel 25 is elevated sufficiently to vaporize remaining liquid metal reductant 18 therein which is drawn off through conduit 42 to the condenser 45 . The conduit 42 is required to be relatively large in diameter to permit rapid evacuation of the interior 26 of the vessel 25 . Because the pressure drop between the vessel 25 and the condenser 45 , during vaporization of the reductant metal 18 is low, the specific volume is high and the mass transfer low, requiring a large diameter conduit 42 . Boiling the reductant metal on the shell side is accomplished by heat exchange with a heated fluid on the tube side.
The annular heat exchanger 29 is optionally operated to maintain the expressed liquid in the annulus 28 at a sufficient temperature to flow easily and/or to provide additional heat to the vessel 25 to assist in vaporization of excess reductant metal from the interior 26 thereof. After liquid metal reductant vapor has been removed from the interior 26 of the vessel 25 , a filter cake remains from the slurry 20 . The appropriate valves 93 are closed and the vacuum pump 95 is isolated from the system.
In the condenser 45 , heat exchange plates 46 are positioned in order to cool the reductant metal vapor introduced thereinto. The cooling system 60 is operated in a closed loop and maintained at a temperature sufficiently low that reductant metal vapor introduced into the condenser 45 condenses and flows out of the condenser, as will be disclosed. The cooling system 60 includes a cooler 65 as previously described and the pump 62 . The coolant exits from the cooler 65 through line 114 which enters the heat exchange plates 46 and leaves through a line 115 which joins the line 116 to interconnect the head tank 62 and the cooler 65 . As seen in the schematic of FIG. 1 , the heat exchange fluid used in the heating system 50 and the cooling system 60 may be the same or may be different, as the systems 50 and 60 can be maintained separately or intermixed.
Both the vessel 25 and the condenser 45 are operated at least part of the time under a protective atmosphere of argon or other suitable inert gas from the argon supply 85 , the pressure of which is monitored by the transducer 86 , the (argon) supply inert gas 85 being connected to the condenser 45 by a line 117 , the condenser 45 also being in communication with the vessel 25 by means of the oversized conduit 42 . Further, as may be seen, each of the heating system 50 and the cooling system 60 is provided with its own pump, respectively 53 and 63 . As suggested in the schematic of FIG. 1 , the heating and cooling fluid may, preferably be NaK due to its lower melting point, but not necessarily, and as an alternative could be the same as the reductant metal in either liquid or vapor phase, as disclosed.
After sufficient reductant metal 18 has been removed from the slurry 20 , via the filter 27 and the conduit 42 , remaining therein is a combination of the titanium product in powder form and salt made during the exothermic reaction in reactor 15 . Because the resultant dried cake has a smaller volume than the slurry product 20 introduced, when the movable bottom closure 30 is opened, the dry cake falls from the filter 27 into the collection vessel 35 whereupon the combination of salt and titanium fall into the crusher 38 due to the sloped bottom walls 36 . In the event the cake does not readily fall of its own accord, various standard vibration inducing mechanism or a cake breaking mechanism may be used to assist transfer of the cake to the collection vessel 35 . The collection vessel 35 as indicated is maintained under an inert atmosphere at about atmospheric pressure, and after the cake passes through the crusher 38 into the exit or outlet 40 , the cake passes downwardly through valve 39 onto the conveyor 70 . There is a cake spreader or baffle 71 downstream of the valve 39 which spreads the cake so that as it is contacted by a mixture 77 of inert gas, preferably argon, and oxygen flowing counter-current to the direction of the product, the titanium powder is passivated and cooled. Although the conveyor 70 is positioned in FIG. 1 horizontally, it may be advantageous to have the conveyor move upwardly at a slant as a safety measure in the event that closure 30 fails, then excess reductant metal would not flow toward a water wash. In addition, there may be cost advantages in having the product wash equipment on the same level as the separation equipment.
Cooling and passivating is accomplished in the cooler 79 with blower 75 which blows a cooled argon and oxygen mixture through a conduit 121 to the product, it being seen from the schematic that the counter-current flow of argon and oxygen with the product has the highest concentration of oxygen encountering already passivated and cooled titanium so as to minimize the amount of oxygen used in the passivation process. Oxygen is conducted to the system from a supply thereof 76 through a valve 93 and line 122 and is generally maintained at a concentration of about 0.1 to about 3% by weight. The mixture of passivated titanium and salt is thereafter fed to a wash system not shown. Various flow meters 81 are positioned throughout the system as required, as are pressure control valves 89 and pressure transducers 86 . A filter backwash valve 91 is positioned so that the filter 27 can be backwashed when required if it becomes clogged or otherwise requires backwashing. Standard engineering items such as valves 93 , vacuum pump 95 and pressure transducers 86 are situated as required. Symbol 100 is used to denote that parallel systems identical or similar to all or a portion of the system 10 illustrated may be operated simultaneously or in sequence.
In the Armstrong process, the production of the metal, alloy or ceramic is continuous as long as the reactants are fed to the reactor. The present invention provides a separation system, apparatus and method which permits the separation to be either continuous or in sequential batches so rapidly switched by appropriate valving as to be as continuous as required. The object of the invention is to provide a separation apparatus, system and method which allows the reactor(s) 15 in a commercial plant to operate continuously or in economic batches. Reduction of the distillation time in vessel 25 is important in order to operate a plant economically, and economics dictate the exact size, number and configuration of separation systems and production systems employed. Although described with respect to Ti powder, the invention applies to the separation of any metal, alloy thereof or ceramic produced by the Armstrong process or other industrial processes.
The heating mechanism shown is by fluid heat exchange, but heaters could also be electric or other equivalent means, all of which are incorporated herein. The bottom closure 30 is shown as hinged and is available commercially. The closure 30 may be clamped when shut and hydraulically moved to the open position; however, sliding closures such as gate valves are available and incorporated herein. Although the reactor 20 is shown separate from the vessel 25 , the invention includes engineering changes within the skill of the art, such as but not limited to incorporating reactor 20 into vessel 25 . Although vessel 35 is illustrated in one embodiment, the vessel 35 could easily be designed as a pipe. Also, the crusher 38 could be located in vessel 25 or intermediate vessel 25 and vessel 35 . Moreover, the cake forming on the filter 27 may be broken up prior to or during or subsequent to removal of the liquid metal therefrom. Similarly, when referring to an inert environment, the invention includes a vacuum as well as an inert gas. An important feature of the invention is the separation of vessels 25 and 35 so the environments of each remain separate. That way, no oxygen can contaminate either vessel.
In one specific example, a reactor 15 producing 2 million pounds per year of titanium powder or alloy powder requires two vessels 25 , each roughly 14′ high and 7′ in diameterwith appropriate valving, so that the reactor 15 would operate continuously and when one vessel 25 was filled, the slurry product from the reactor would switch automatically to the second vessel 25 . The fill time for each vessel 25 is the same or somewhat longer than the deliquor, distill and evacuation time for vessel 25 .
Changing production rates of reactor 15 simply requires engineering calculations for the size and number of vessels 25 and the related equipment and separation systems. The invention as disclosed permits continuous production and separation of metal or ceramic powder, while the specific example disclosed permits continuous separation with two or at most three vessels 25 available for each reactor 15 . With multiple reactors 15 , the number of vessels 25 and related equipment would probably be between 2 and 3 times the number of reactors.
While there has been disclosed what is considered to be the preferred embodiment of the present intention, it is understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.
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A system and method of separating metal powder from a slurry of liquid metal and metal powder and salt is disclosed in which the slurry is introduced into a first vessel operated in an inert environment when liquid metal is separated from the metal powder and salt leaving principally salt and metal powder substantially free of liquid metal. The salt and metal powder is transferred to a second vessel operated in an inert environment with both environments being protected from contamination. Then the salt and metal powder are treated to produce passivated powder substantially free of salt and liquid metal. The method is particularly applicable for use in the production of Ti and its alloys.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to devices used to clean the area beneath one's fingernails, and more specifically to a fingernail cleaning device that provides for enhanced cleaning by incorporating a special filament that is manually inserted beneath and drawn along the fingernail edge in order to remove highly concentrated, deeply impacted and difficult to remove dirt, grease and grime typically experienced by those such as mechanics, machinists, factory workers or others that work in extremely dirty and greasy environments.
2. Description of the Related Art
Proper grooming and manicuring principles dictate that one must maintain a neat and clean appearance around and under one's fingernails. In particular, when referring to the cleaning and removal of dirt from underneath one's nails, a scraping instrument such as a knife, pointed end of a file or other like sharpened implement is used to accomplish the removal of the bulk of the dirt and debris deposited therein. This process may or may not be either preceded or followed by cleansing with soap and/or water. For the most part, when speaking in terms of the average person, this practice is sufficient to provide adequate cleansing of the area beneath the fingernail. However, in the case of mechanics, machinists, factory workers and others that work in extremely dirty and greasy environments on a hands-on basis require a more thorough and rigorous cleaning in order to clean their hands and, especially, beneath their fingernails. A search of the prior art did not disclose any patents that read directly on the claims of the instant invention. However, several references depicting fingernail cleaning devices were considered related. In general, these devices are far more complex in design than the present invention and many are directed toward automated, non-portable devices incorporating the use of a variety of electro-mechanical systems to complete the task. Lacking the simplicity transportability of the present invention, these devices neither anticipate nor disclose any embodiment that would preclude its novelty and the utilitarian functionality of its features.
U.S. Pat. No. 5,713,378, issued in the name of Smith, discloses an automated fingernail cleaning device in which the user's finger is enclosed in a protective shroud that houses a spray nozzle. The nozzle is connected to a base pumping unit that delivers pressurized water, cleaning the dirt and debris from under the nail.
U.S. Pat. No. 4,635,656, issued in the name of Daniel, discloses a fingernail cleaning device that attaches to a conventional sink spigot. The device includes an orifice disc for projecting a narrow, high velocity jet of water that is housed in a cylindrical, tubular housing. The user inserts his/her finger into the housing and the fingernail is cleaned by the water jet.
U.S. Pat. No. 4,137,929, issued in the name of Grossman, discloses a fingernail cleaning device consisting of an open receptacle capable of receiving a plurality of fingers. The device also consists of a plurality of jets whose source of water requires either a normal hydrant with sufficient pressure, or a pulsating pump motor.
U.S. Pat. No. 4,289,152, issued in the name of Fuhre, discloses a fingernail cleaning apparatus consisting of a large housing with a finger-sized aperture into which a finger is inserted. The apparatus utilizes an electric motor for operating a water-discharging pump which in turn projects pressurized water against the inside surface of the fingernail.
U.S. Pat. No. 4,742,836, issued in the name of Buehler, discloses a fingernail cleaning device whereby all the fingernails on the user's hand can be rapidly and effectively cleaned at one time. The device consists of an open-topped receptacle for enabling the fingers of one hand of the user to be placed therein. Positioned at an angle to the base of the receptacle is a small diameter fluid passageway. Such passageway directs water at a downward angle to the upper surface of the receptacle base thereby creating a high-velocity, fan-shaped stream of water which travels along the bottom of the receptacle in the direction of the fingernails of the user.
All of these devices depart substantially from the spirit, functionality and design of the present invention. Aside from the fact that they all incorporate a different cleansing medium to complete the desired purpose, they are all excessively large, bulky and lack the transportability of the present invention. Furthermore, these devices require connection to an electrical wall socket, to a water supply or both.
U.S. Pat. No. 5,640,979, issued in the name of Trenary, discloses an automated fingernail cleaning device which utilizes a rotating brush, actuated by an electric motor and housed within a protective shield into which the user's finger is placed.
U.S. Pat. No. 4,180,884, issued in the name of Hess et al., discloses an automated fingernail cleaning apparatus which utilizes a disc-shaped rotary brush to obtain effective cleaning action for the fingernails. The rotary brush, which is mounted inside a housing, is driven by an electric motor. The apparatus is capable of cleaning all of the fingers on one hand simultaneously.
U.S. Pat. No. 4,123,816, issued in the name of Lupo, discloses an automated fingernail cleaning apparatus which utilizes a rotating bristle brush for the cleaning of one's fingernails. The rotating bristle brush is connected to a drive shaft, which in turn is actuated by an electric motor.
These devices, as well, depart substantially from the spirit, functionality and design of the present invention. Aside from the fact that they all incorporate a different cleansing medium to complete the desired purpose, they are all excessively large, bulky and lack the transportability of the present invention. Furthermore, these devices require connection to an electrical wall socket or the incorporation of a battery pack in order to supply the required electrical energy.
U.S. Pat. No. 2,424,509, issued in the name of Singer, discloses a fingernail cleaning device which consists of a plurality of upwardly opened, rubber sockets into which a finger is inserted. By engaging in a rotary motion, the wall of each socket will impart a thorough scrubbing to the finger. The rotation of each socket can be actuated either by mechanical operation, via hand crank, or by the operation of a mountable electric motor. The device is limited in that it targets the finger and not the fingernail for cleansing and thus provides a little, if any, effective nail cleaning.
U.S. Pat. No. 5,090,427, issued in the name of Sherts, discloses a finger groomer attachment for a writing instrument. The apparatus performs a variety of manicure operations which are accomplished through the incorporation of various multi-functioning devices. One such device is a fingernail cleaner. Because the fingernail cleaner is thin and pointed, it enables a user to scrape underneath a fingernail to remove dirt and foreign matter. The apparatus is unlike the present invention in that it utilizes a solid, pointed scraping implement rather than a cleaning filament to clean underneath one's fingernails.
U.S. Pat. No. Des. 289,345, issued in the name of Fine, discloses an ornamental design for a fingernail cleaner brush. The device consists of a base portion with bristles embedded therein. Because the device utilizes the bristles of a brush rather than a cleaning it provides a very limited margin of effective cleaning under one's fingernails.
While several features exhibited within these references may be incorporated into this invention, alone and in combination with other elements, the present invention is sufficiently different so as to make it distinguishable over the prior art.
SUMMARY OF THE INVENTION
The filament cleaning tool for fingernails, according the preferred embodiment of the present invention, consists of a length of flexible cleaning filament connected at each end to a small rigid securing ring. Constructed of stainless steel, plastic, nylon or other like suitable materials, the cleaning filament is of a light gauge yet, due to the material construction, is strong, durable, waterproof and easy to clean. The construction of the cleaning filament is such that a series of bristles, flays or scale-like protrusions are positioned along its length. Used in conjunction with soap and water, the user first washes his or her hands thoroughly. Leaving the hands and fingers lathered, the user places one securing ring on the thumb and one on the forefinger of the same hand. Drawing the cleaning filament taut, the use then inserts the cleaning filament underneath the fingernail of a single finger on the hand opposite the hand used to support the tool and draws the filament in a back and forth motion along the nail, adjusting the depth so as to cover the entire surface area thereof. Intended primarily for use by those with large amounts of impacted dirt, grease and grime beneath their nails, the bristles, scales or flays, in conjunction with the soap lather will remove even the most stubborn deposits. The user repeats this procedure for each finger, switching hands in order to cover the fingers on both the right and left hand, and rinses the dirt and grime from the tool when finished. The simple design of the fingernail cleaning filament tool, in conjunction with its size, material construction and ease of use makes it the ideal method by which to clean one's nails.
It is therefore an object of the present invention to provide a filament cleaning tool for fingernails that incorporates the use of a flexible cleaning filament to remove dirt, grease and grime from beneath one's fingernails.
It is another object of the present invention to provide a filament cleaning tool for fingernails wherein the cleaning filament includes a plurality of flays, bristles, scales or other like protrusions or configurations that will aid in the efficient removal of dirt, grease and grime from beneath one's fingernails.
It is another object of the present invention to provide a filament cleaning tool for fingernails wherein its use in conjunction with soap and lather will allow even the most stubborn or impacted dirt, grease and grime to be removed from beneath one's fingernails.
It is another object of the present invention to provide a filament cleaning tool for fingernails small, compact and easy to use.
Finally, It is an object of the present invention to provide a filament cleaning tool for fingernails that is simple in construction and makes use of materials that are strong, durable and cost-effective to manufacture.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages and features of the present invention will become better understood with reference to the following more detailed description and claims taken in conjunction with the accompanying drawings, in which like elements are identified with like symbols, and in which:
FIG. 1 is a front view of the filament cleaning tool for fingernails, according to the preferred embodiment of the present invention;
FIG. 2 is a magnified view of a segment of a flayed cleaning filament for use in conjunction with the filament cleaning tool for fingernails, according to the preferred embodiment of the present invention;
FIG. 3 is a magnified view of a segment of a bristled cleaning filament for use in conjunction with the filament cleaning tool for fingernails, according to the preferred embodiment of the present invention;
FIG. 4 is a magnified view of a segment of a scaled cleaning filament for use in conjunction with the filament cleaning tool for fingernails, according to the preferred embodiment of the present invention;
FIG. 5 is a perspective view of the filament cleaning tool for fingernails depicting its use in accordance with the preferred embodiment of the present invention; and
FIG. 6 is a front view of the filament cleaning tool for fingernails, according an alternate embodiment of the present invention.
LIST OF REFERENCE NUMBERS
10 Filament Cleaning Tool For Fingernails
11 Securing Rings
12 Cleaning Filament
13 Filament Securing Aperture
15 Flayed Cleaning Filament
16 Flayed Filament Body
17 Flays
20 Bristled Cleaning Filament
21 Bristled Filament Body
22 Bristles
25 Scaled Cleaning Filament
26 Scaled Filament Body
27 Scales
30 Hand
31 Thumb
32 Forefinger
33 Fingernail
35 Handle
DESCRIPTION OF THE PREFERRED EMBODIMENTS
1. Detailed Description of the Figures
Referring now to FIG. 1, depicted is a filament cleaning tool for fingernails, hereinafter cleaning tool 10 , according to the preferred embodiment of the present invention. The cleaning tool 10 consists of a pair of securing rings 11 with a cleaning filament 12 connected thereto and spanning therebetween. The securing rings 11 are rigid in nature, constructed of metal, plastic or other materials of like qualities and are waterproof so as to withstand prolonged use. Each securing ring 11 has a filament securing aperture 13 , protruding from the edge thereof, that is used to secure the cleaning filament 12 to the securing ring 11 . In the preferred embodiment, the filament securing aperture 13 consists of a nipple-type protrusion with a cylindrical aperture of a diameter slightly larger than that of the cleaning filament 12 bored therethrough. The cleaning filament 12 is passed through the filament securing aperture 13 and tied in a knot, thus securing it for use. It is envisioned, however, that a variety of methods exist that can be used to attach the cleaning filament 12 to the securing ring 11 . By way of example and not of limitation, the cleaning filament 12 could be secured by tying it directly around the securing ring 11 or a tangential slot could be cut into the body of the securing ring 11 itself, allowing the cleaning filament 12 to be inserted therein and held secured by a friction fit.
Referring now to FIGS. 2-4, a variety of designs and material constructions exist for the cleaning filament 12 . Stainless steel, nylon and plastic are all ideal materials with which to construct the cleaning filament 12 , both alone and in combination with one another, although it is envisioned that a variety of alternative materials available from the plastics and textile industries would be equally suited.
As shown in FIG. 2, a flayed cleaning filament 15 consists of a single strand of filament material having a flayed filament body 16 with a series of generally pointed flays 17 protruding longitudinally therefrom along its entire length, arranged 360 degrees about its circumference. The flays 17 are created by cutting into a solid strand of filament material (not shown) at an acute angle, such that a pointed contour results, at various locations along its length and about its circumference.
As shown in FIG. 3, a bristled cleaning filament 20 consists of a single strand of filament material having a bristled filament body 21 with a series of bristles 22 , protruding in a direction generally perpendicular to the longitudinal axis of the bristled filament body 21 , spaced along its entire length and arranged 360 degrees about its circumference. The bristled filament body 21 consists of twisted or braided stainless wires (not shown) with the stainless steel, plastic, or nylon bristles 22 interwoven at various positions along its length and oriented at varying angles with respect to one another while maintaining a generally perpendicular orientation with the longitudinal axis of the bristled filament body 21 .
As shown in FIG. 4, a scaled cleaning filament 25 consists of a single strand of filament material having a scaled filament body 26 with a series of generally rounded scales 27 protruding longitudinally therefrom along its entire length, arranged 360 degrees about its circumference. The scales 27 are created by cutting into a solid strand of filament material at an acute angle, such that a rounded contour results, at various locations along its length and about its circumference.
Referring now to FIG. 6, depicted is the cleaning tool 10 , according to an alternate embodiment of the present invention. In this embodiment, the cleaning filament 12 is of a pulled taught between a handle 35 of a rigid nature such that it can be grasped by a handle 35 and used in a manner similar to that of a conventional nail file or other nail cleaning implement. The cleaning filament 12 incorporated into the alternate embodiment assumes the varying designs of those depicted in FIGS. 2-4. The differences of this alternate embodiment the replacement of the finger rings with an elongated, rigid handle with the filament being drawn across. In this manner the filament can be drawn back and forth with the opposing hand in a manner similar to that of the preferred embodiment.
The aforementioned cleaning filament designs are by way of example and not of limitation as it is envisioned that a variety of alternative cleaning filament designs could be equally as effective. For example, a braided or twisted filament alone could be used effectively, or a solid strand filament could be distorted along its length, using a rolling die or the like to create a wide variety of cleaning filament configurations.
2. Operation of the Preferred Embodiment
In accordance with the preferred embodiment of the present invention and as shown in FIG. 5, the cleaning tool 10 is used in the following manner to remove dirt, grease and grime from beneath the fingernails:
The user would first wash his or her hands 30 , applying a generous amount of soap and lather (not shown). Without rinsing the soap from the hands, the user would then secure the cleaning tool 10 to one hand 30 by placing a securing ring 11 over the thumb 31 and forefinger 32 , respectively. Drawing the cleaning filament 12 taut, the user then inserts the cleaning filament 12 underneath the fingernail 33 on the hand opposite that of the cleaning tool 10 , between the nail and the skin, and draws it along in a back and forth motion generally parallel to the edge of the fingernail 33 . The flays 17 , bristles 22 or scales 27 , depending on the particular cleaning filament 12 configuration, create an abrasive force that serves to remove the material impacted beneath the fingernail 33 . The soap lather enhances the effectiveness of the cleaning tool 10 . By altering slightly the depth at which the cleaning filament 12 is inserted, the entire area underneath the fingernail 33 can be cleansed. This procedure is carried out on all of the affected fingernails 33 and, when done, the user simply rinses the cleaning tool 10 clean and stores it for future use.
In the alternate embodiment, the follows the same basic procedures as that of the preferred embodiment, taking into account that the accommodations for a flexible cleaning filament 12 are not required. Grasping the cleaning tool 10 by the handle 35 , the user can insert the cleaning filament 12 beneath the nail, forcing it back and forth in order to remove dirt and grime.
While the preferred embodiments of the invention have been shown, illustrated, and described, it will be apparent to those skilled in this field that various modifications may be made in these embodiments without departing from the spirit of the present invention. It is for this reason that the scope of the invention is set forth in and is to be limited only by the following claims.
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Disclosed is a filament cleaning tool for fingernails wherein a length of flexible cleaning filament connected at each end to a small rigid securing ring. Inserted beneath the fingernail, the cleaning filament contains a series of bristles, flays or scale-like protrusions, positioned along its length, that remove dirt, grease and grime from beneath the fingernail as it is drawn back and forth therein.
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BACKGROUND OF THE INVENTION
[0001] The present invention relates to a method for the production of molten metal by reduction of oxides of the metal. This includes production of molten iron, including pig iron and cast iron, as well metal alloys.
[0002] Reduction processes are intended to either produce steel directly from iron ore or make a product equivalent to blast furnace pig iron for use in conventional steel making processes, or produce low-carbon iron as a melting stock for producing steel by conventional processes. This process is generally intended to supplant blast furnaces as a source of molten iron production for steel making.
[0003] Blast furnaces typically constitute a vertical tower wherein a charge comprising iron ore, pellets or agglomerates, together with coke and limestone, are sequentially charged through the top of the furnace to form a continuous column of charge material. In the lower portion of the furnace, atmospheric air, which may be preheated, is introduced to the charge. When the charge materials come into contact with hot gases that are ascending from the hearth, the coke is preheated by these gases so that when it reaches the lower portion of the furnace and it comes into contact with the air introduced thereto, it will be caused to bum. At the resulting high temperatures existing at this location of the furnace, carbon dioxide is not stable and reacts immediately with carbon to form carbon monoxide. This reaction is not only the main source of heat for the smelting operation, but it also produces a reducing gas (CO) that ascends through the furnace where it preheats and reduces the iron oxide in the charge as it descends through the furnace.
[0004] The production capacity of a blast furnace is a function of the internal volume or area of the furnace design parameters for a given production capacity. Consequently, to increase capacity requires increasing the size of the blast furnace and accordingly adjusting the design parameters.
SUMMARY OF THE INVENTION
[0005] The present invention provides improvement over the above-described conventional blast furnace operation in the production of molten metal, particularly molten iron. Specifically, the method in accordance with the invention is used in association with a shaft furnace that may produce cast iron, pig iron or other metal alloys in a more cost effective manner than the use of conventional smelting operations, including blast furnaces.
[0006] The invention provides further advantage in allowing the conservation of fine materials from the top gases in the form of oxides of metals, such as zinc, cadmium and the like and permits the recovery and recycling of these metals and oxides.
[0007] The method for reducing metal oxides in accordance with the improvement of the present invention provides advantages over the conventional practices by the novel use of a shaft furnace for smelting. In this regard the method comprises reacting a charge of a metal oxide and a reductant to produce a primary molten metal of the metal oxide and gas containing carbon monoxide and an additional secondary metal and oxides, which are different than the primary molten metal and metal oxides. The gas is directed upwardly in the shaft furnace and away from this charge. The temperature of the gas is controlled at a location in the shaft furnace above the charge to be at a temperature that is higher than the condensing temperature of the secondary metal and oxides. This prevents the secondary metals and oxides in the gas from adhering to the interior wall of the shaft furnace. Thereafter as the gas passes upwardly and is removed from the furnace the secondary metal and oxides are removed from the gas. These may then be recycled in various ways, including using the same in the production of agglomerates for use in a charge to be refined.
[0008] The temperature of the gas may be controlled by varying the height of the charge within the shaft furnace. In addition the temperature of the gas may be controlled by varying the combustion rate of the gas by using a burner to heat the gas as the gas is directed upwardly within the shaft furnace.
[0009] The temperature of the gas may be additionally controlled by controlling the reaction rate of the charge.
[0010] The gas removed from the furnace consists essentially carbon dioxide and nitrogen.
[0011] The charge may include iron ore. In addition, the charge may include agglomerates that are self-reducing, self-fluxing, or both.
[0012] In conventional reduction practices, the reduction occurs by means of the CO generated from the partial combustion of the coke. The CO spreads into the charge with the reduction taking place according to the reaction Me+CO=>Me+CO 2 . The CO 2 gas generated in this reaction spreads in the opposite sense to the CO. This reaction requires a certain amount of time for the complete diffusion inside the charge. This requires furnaces with periods of residence times for the charge inside the furnace, which is typical of blast furnaces.
[0013] Self-reducing agglomerates, however, exhibit conditions that are significantly more favorable for reduction. The more intimate contact between the ore or the oxide and the carbon of the reductant (coal or coke) allows a shorter reaction time since there is no need for spreading the CO into the agglomerate. The reduction occurs according to the reactions below, and is preset within the agglomerate for this purpose:
2MeO+C==>2Me CO 2
CO 2 +C==>2CO
MeO+CO==>Me+CO 2
[0014] The agglomerate itself thus establishes in practice a semi-closed system, wherein the atmosphere is a reducing atmosphere, during the entire period when carbon is available within the agglomerate. In other words, the self-reducing agglomerates, as implied by such designation, maintain within the same their own reducing atmosphere that is independent from the characteristics of the outer atmosphere, that is the atmosphere existing inside the shaft furnace provided by the ascending gasses.
[0015] It is therefore possible to convert into energy for the process the CO present in the atmosphere of the furnace provided by the partial burning of the fuel and the reducing reaction that takes place within the agglomerates and additionally allowing control of the temperature and the characteristic (oxidizing or reducing) of the top gasses.
[0016] In melting processes using shaft furnaces, the presence of coke or another fuel in solid form, charged through the top part of the furnace during the course of the operation, follows a descending path with the rest of the charge, reacting with the ascending CO 2 , in counter current relationship according to the reaction CO 2 +C==>2CO. This results in a greater consumption of carbon material, and thus prevents effective utilization thereof for the process of reducing/melting.
[0017] Due to the short residence time required for the self-reducing process in accordance with the invention, it is possible to operate the furnace according to the present invention with low charge heights. It is also possible to control the exhaust temperature of the top gasses and hence maintain in the form of vapor or fine particulate the oxides or metals that contaminate the residue used in the agglomerates. Hence, this material may be recovered at the gas scrubbing system. Because reduction of the content and the nonmetallic present in the residue, the fines recovered at the gas scrubbing system exhibit high concentrations of these oxides and metals, such as for example above 20%, rendering the subsequent recovery thereof economically feasible. Where the concentration of the oxides or metals is not found to have reached the desired level for economical recovery, it is possible to recycle these fines as many times as necessary by including the same in the production of the self-reducing agglomerates to increase the content thereof in the agglomerates and thus increase the concentration thereof in the recovered fines.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] [0018]FIG. 1 is a schematic partial perspective view of one embodiment of equipment for practicing the present invention.
[0019] [0019]FIG. 2 is an elevation view of the equipment of FIG. 1.
[0020] [0020]FIG. 3 is a cross-sectional view showing the charge distribution devices of this equipment.
[0021] [0021]FIG. 4 illustrates a gas scrubbing system capable of retaining the metals vaporized inside the furnace and the fines of metal oxides that leave the furnace together with the top gasses.
[0022] [0022]FIG. 5 is a cross sectional view of a hood structure containing burners for controlling combustion of the off gas from the furnace.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The furnace according to the present invention permits control of the exhaust temperature of the hot gasses through the greater or lesser burning rate of the combustible gasses provided from the lower regions and the reduction of the oxides present in the agglomerates. In this manner, it is possible to maintain in the vapor or fine particulate state the metals and oxides present in the raw agglomerates. This includes materials having vaporization temperatures below 1,000° C., such as Zn, Cd, and Pb, which would otherwise condense on the walls of the furnace.
[0024] Therefore, the hot gasses at high temperatures and containing the vapor of the contaminant metals or the oxides thereof in the form of fine particles are exhausted from the furnace and, as shown in FIG. 4, through the gas outlet 3 into the gas scrubbing system, wherein there occurs, at the separating devices 6 (for example, cyclone or precipitator type devices), the condensing of those vapors and the separation thereof, together with the remaining fines, from the top gasses, that follow a course through the remaining portion of the gas scrubbing system 7 .
[0025] The fines captured in these separators 6 have concentrations above 20% of contaminant metals or oxides due to the decrease in the rate of iron present in the raw materials, rendering the recovery thereof economically feasible.
[0026] Should the amount of residue containing contaminants fail to be sufficient to ensure an economically feasible concentration of these metals or oxides, it is possible to operate the furnace of the instant invention by charging the agglomerates containing these contaminants only at one sector of the furnace, such as for example to one of the ends thereof, and to withdraw and separate these metals prior to the complete mixture of the top gasses of the rest of the furnace in order to provide the concentration thereof at economically feasible levels.
[0027] That novel furnace construction, as shown in FIGS. 1 to 3 , is essentially comprised of an upper shaft 1 , cylindrical or conical, having a rectangular cross sectional shape including at the upper part thereof a charging device or devices including port(s) 2 , provided with charge distributing devices 4 to allow the positioning of the agglomerates or charge in proper positions inside the furnace to concentrate the agglomerates that contain the metals or oxides that are intended to be concentrated. A gas outlet or outlets 3 for discharging gasses comprising mainly various contents of CO 2 , CO, H 2 , and N 2 , in addition to the fines produced by the disintegration of the charge. The vapors or oxides in the form of particulate may flow along ducts 5 to the gas scrubbing system 7 and the separator devices for fines 6 that retain the condensed particulate of metal or oxides. The gasses are thereafter conveyed to the recovering devices or heat regenerators (not shown), to pre he blowing air or for any other purpose.
[0028] In the upper shaft 1 there is a row or rows of tuyeres 8 that blow hot or cold air, either enriched with O 2 , or not thus enriched, for the burning reaction of CO and any other combustible gasses that may be present, to carbon dioxide according to the reactions:
C+O 2 ==>CO 2
CO+½O==>CO 2
2H 2 +O 2 ==>2-H 2 O
[0029] supplying heat to the charge constituted by self-reducing agglomerates, ore or iron oxides and residue containing iron and contaminants, and being self-fluxing or not, pig, scrap, sponge iron, either in the form of briquettes or otherwise, foundry or steel plant scrap, or mixtures of those components in the various possible proportions.
[0030] The equipment or furnace also includes a lower shaft 9 , of cylindrical or conical shape, with a rectangular cross sectional shape, having larger sides at the upper part thereof than the upper shaft 1 , sufficient for the positioning of feed devices to feed coke or coal or any other solid fuel. Around the lower shaft 9 , at a level sufficiently higher than the base of the upper shaft 1 , there is provided a continuous fuel feed section, as shown in FIG. 2, this section being fed by piping or other feed sections fed by tight valves 10 for solid fuel. Optionally, independent pipes 11 to feed additional combustible materials may be added to the solid fuels feed section to provide a proper feeding of the fuel bed, especially of fine materials that might otherwise be drawn by the gasses from the central upper shaft 1 , or of combustible materials such as used tires, plastics, etc.
[0031] The lower shaft 9 includes one or more rows of primary tuyeres 12 positioned to blow preheated or not preheated air, either enriched with O 2 or not, and to inject liquid, gaseous or solid powdered fuels for partial or total burning of the fuel, providing the thermal energy required to reduce and/or melt the charge. The upper shaft 1 and the lower shaft 9 may include a monolithic refractory material (shown in cross-hatched lines in FIGS. 3 and 4) and may further include cooling means.
[0032] The fused metal and the slag leave the furnace through the lower part thereof.
[0033] The fuel in this type of furnace need not be added together with the charge at the top of the shaft as in conventional practices.
[0034] This furnace provided with such improvements has distinct atmosphere zones, with characteristics that may be regulated by means of the type of fuel employed and the greater or lesser injection of comburent at the various points provided for that purpose. It is thereby possible, depending of the oxidizing potential by CO 2 of the metal to be recovered and the characteristic (oxidizing or reducing) of the atmosphere prevalent inside the furnace, to recover that metal in oxidized or metallic form.
[0035] The gasses coming from the lower zone, flowing back against the charge, transfer to the latter the thermal energy required for heating and reducing or simple melting.
[0036] Since the charge in the upper shaft 1 does not contain significant amounts of coke, charcoal or other solid fuel, the Boudouard reaction, CO 2 +C==>2CO, which absorbs heat and which in addition consumes considerable amounts of carbon, is minimized. Thus, the exhaust gasses that leave the equipment are comprised essentially of CO 2 and N 2 . However, in operating modes variable rates of CO capable of providing a reducing characteristic to the top gas and sufficient heating power to be used for preheating the blowing air or in other parts of the plant may be used.
[0037] Since it is possible to control the atmosphere within the furnace as well as the temperature of the top gasses, it is possible in this furnace to avoid the accumulation of metals and/or oxides entrained in the off gas on the inner walls of the furnace as typically occurs in the case of cupola furnaces and blast furnaces.
[0038] The method of the present invention allows great flexibility in operation enabling the melting of scrap (including scrap containing high rates of contamination of other metals besides iron, such as, for example, zinc), pig iron, sponge iron or any other type of pre-reduced material, which may be in the form of briquettes.
[0039] This shaft furnace thus operated in accordance with the method of the invention presents the advantage over the cupola furnace or blast furnace of providing great fuel economy, since the carbon monoxide or other gasses formed in the lower part of the furnace may be burned at the upper part. This transfers the thermal energy yielded during the reaction to the charge descending through the shaft. The exhaust gasses are formed essentially by carbon dioxide, nitrogen, water vapor and controlled amounts of carbon monoxide, hydrogen and hydrocarbons.
[0040] This shaft furnace also may be operated in accordance with the invention for reducing and melting of self-reducing agglomerates of ore or industrial residue with or without metallic contaminants that may be recovered as vapor or fines of the oxides thereof from the top gasses. Also in this case, the carbon monoxide that is formed is burned along the shaft, and the heat thereby generated is almost entirely transferred to the descending charge, thereby considerably increasing the thermal efficiency of the equipment. Additionally, since the equipment does not include layers of coal or coke or other solid fuels in the charge of the shaft, the reaction CO 2 +C==>2CO does not occur to provide a reduction of fuel consumption.
[0041] The solid fuel feeding section is also provided with a gas removal device 13 equipped with flow control valves 14 capable of ensuring the passage of a certain amount of the gas to provide preheating, predrying and distillation of volatile fractions present in various solid fuels, such as mineral coal, firewood, and/or various carbonaceous residue.
[0042] To regulate and increase the temperature of the off gas to prevent condensing of metal deposits the hood 16 of the furnace may have a burner to heat this gas.
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A method for reducing metal oxides in a shaft furnace. A charge of metal oxide and a reductant is reacted in the furnace to produce a primary metal of the metal oxide and an additional secondary metal. The temperature of the off gas from the reaction is controlled to prevent condensing of the secondary metal so that it remains in the off gas for separation therefrom.
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BACKGROUND OF THE INVENTION
The invention relates to a drinks dispensing device provided with a cooling chamber having a wall, and on one side an opening for receiving a drinks container, a shut-off valve, which is hingedly connected to the wall, for the purpose of shutting off the opening, and a tap head, which is connected to the wall and is used to receive a shut-off valve of a drinks container which has been positioned in the cooling chamber, the tap head comprising a displacement member, a seat connected to the displacement member and a handle connected to the seat.
DESCRIPTION OF THE RELATED ART
A drinks dispensing device of this type is known from PCT/NL99/00454. The known dispensing device comprises a cooling chamber in which packaging containing carbonated drink, such as beer, can be placed. The packaging containing carbonated drink comprises an outer container made from plastic and an inner, flexible bag which contains the carbonated drink. The flexible bag is connected, via a filing and dispensing head, to the neck of the outer container. The dispensing head is provided with a first, relatively wide filling passage, to which a filling head of a filling line can be connected for the purpose of filling the flexible bag. After the bag has been filled and the filling head of the filling line has been detached, the filling passage of the filling and dispensing head is closed by means of a spring-loaded valve. A second, relatively narrow dispensing channel of the filling and dispensing head is connected to a flexible hose which extends at right angles to the longitudinal direction of the container. Before the container is positioned in the cooling chamber of the drinks dispensing device, the dispensing passage is likewise closed off by means of a spring-loaded valve. A plastic outlet part which is provided with a guard bearing a brand name is attached at right angles to the end of the flexible hose, which outlet part can be positioned in a receiving part of the dispensing head of the drinks dispensing device. The dispensing head comprises two pivotable parts, which delimit a through-passage for the flexible line, and a shut-off valve connected to a tap handle. The shut-off valve comprises a spring-loaded valve mechanism which, through actuation of the tap handle, can squeeze shut the flexible hose in the through-passage and can also open this hose.
After the flexible hose has been positioned in the through-passage, the dispensing head is closed and the tap handle is placed in the closed position. It is then possible to close a cover of the dispensing device and pressure means, such as a compressor, can be connected to the container for supplying a pressurized medium to the space between the wall of the outermost container and the flexible bag. When the cover of the pressure chamber of the dispensing device is closed, the dispensing passage of the filling and dispensing head is opened, so that the contents of the flexible bag are forced into the flexible hose. Opening the tap handle opens the flexible hose so that it adopts its free, undeformed cross section, and the carbonated drink is dispensed from the dispensing head under pressure. The known dispensing device is also provided with a cooler, such as a Peltier element, for cooling the drink.
The known drinks dispensing device is intended to be positioned at an accessible location for the user so that the drink in a fitted drinks container, such as for example beer, can be kept under pressure for a period of a number of weeks at a cooled, drinkable temperature. It is in many cases desirable for the contents of the drinks dispensing device only to be accessible to some members of a family and, if the drinks container contains beer or another drink which is unsuitable for consumption by minors, for it to be easy to prevent the device from operating.
Furthermore, it is desirable for it to be easy to adapt the dispensing device according to the content of the dispensed drink, so that it is clear to a user what the drinks dispensing device contains.
A further requirement imposed on the drinks dispensing device is that its appearance can easily be adapted to the wishes of the user and for it to be possible for this appearance to be adapted to the interior of the environment in which it is used.
SUMMARY OF THE INVENTION
For this purpose, the drinks dispensing device according to the invention is characterized in that the handle can be removed from the seat by a user, it being impossible for a user to move the displacement member without a handle.
After the handle has been removed from the seat, the displacement member can no longer be moved by hand, or at least not without considerable effort, so that the drinks dispensing device is deactivated for young people, in particular children. This provides a very simple and effective childlock.
Furthermore, the fact that the handle can be removed means that it can be exchanged for a handle with a different appearance but with the same type of connecting member, so that the drinks dispensing device can be provided with a handle which corresponds to the contents. This makes it possible to use different types of beer with a matching handle, different types of soft drinks with a matching handle, etc., so that it will immediately be clear to the user what type of drink will be dispensed.
It is also possible for the handles to be of various designs and styles, for example to have a chromium-plated grip and Bakelite bottom, completely chromium-plated, with a handle designed as a golf ball and other specialized designs of this type.
According to one embodiment, the handle is provided with a connecting member which, in the vicinity of or below the surface of the seat, on the latter. The seat may, for example, have a cylindrical bore in which the handle is secured by means of a screwthread, bayonet fitting or spring pawl. It is also possible for the seat to comprise a pin of the displacement member, with a cavity lying transversely with respect to the pin, the handle being provided with a grip, a widened holding part and a connecting part which lies transversely with respect to the grip and is secured in the cavity in the pin.
The connecting member of the handle is preferably designed in such a manner that it can be removed and fitted by the user without having to use a tool.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of a drinks dispensing device according to the invention will be explained in more detail with reference to the appended drawing, in which:
FIG. 1 shows a longitudinal section through a drinks dispensing assembly for use at the consumer's home;
FIG. 2 shows a longitudinal section through an embodiment of a drinks dispensing assembly which is suitable for use at small-scale catering establishments;
FIGS. 3 and 4 show cross sections through the dispensing head of the drinks dispensing device according to the invention;
FIG. 5 shows an exploded view of the dispensing head shown in FIGS. 3 and 4 ;
FIGS. 6 and 7 show an exploded perspective view and an assembled perspective view, respectively, of a further embodiment of a drinks dispensing head; and
FIG. 8 shows a releasable handle which can be attached by means of a screwthread.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a drinks dispensing assembly 1 provided with a dispensing device 2 which has a cooling chamber 3 which can be closed off by a cover 4 . A package 5 of carbonated drink is positioned in the cooling chamber 3 . In the embodiments described below, the carbonated drink is beer, which is accommodated in a flexible bag 6 of the packaging 5 at a superatmospheric pressure of between 0 and 3 bar, for example 1 to 1.5 bar (the equilibrium pressure of CO 2 above beer). However, the packaging may also contain other carbonated drinks, such as soft drinks, at pressures which generally lie between 0 and 5 bar superatmospheric pressure.
The flexible bag 6 is accommodated in an outer rigid container 7 of the packaging 5 and, in the vicinity of a neck, is attached in a sealed manner to a flat lip 9 of a filling and dispensing head 10 . The filling and dispensing head 10 comprises an air passage 11 which can be connected to a pressure line 12 in the cover 4 , which pressure line is connected to a compressor 13 . As an alternative to a compressor, it is also possible to use another form of pressure means, such as a precompressed gas, for example compressed air or pressurized CO 2 which is supplied from a separate cylinder. When the cover 4 is closed, a spring-loaded valve 14 of the filling and dispensing head 10 is displaced downwards, so that an outlet opening 15 is opened and an air passage in the head 10 leading to the space 16 between the flexible bag 6 and the rigid container 7 is opened, which air passage is in communication with the pressure line 12 .
A flexible dispensing line 17 is connected to the filling and dispensing head 10 , and, when the packaging 5 is placed in the cooling chamber 3 , is connected to a dispensing head 18 . The dispensing line 17 comprises, in the vicinity of an outlet end, a shut-off valve 19 , which is positioned releasably in the dispensing head 18 and which has a normally closed position. When the packaging 5 is placed in the dispensing device 2 and the cover 4 is closed, so that the compressor 13 is activated, the shut-off valve 19 is closed and the beer is forced out of the flexible bag into the flexible line 17 , until it reaches the shut-off valve 19 , as a result of the pressure which is built up in the intervening space 16 by the compressor 13 . By actuation of a handle 20 , the shut-off valve 19 , which forms an integral part of the dispensing line 17 , can be opened and the beer can be tapped from the bag 6 . When the packaging 5 is empty or, while the packaging is still partially full, another drinks package is placed into the dispensing device, the container 7 and the flexible dispensing line 17 connected thereto, together with the closed shut-off valve 19 , are removed from the cooling chamber 3 . The container 7 of the empty packaging 5 , which may be formed, for example, from plastic, such as PET or ABS, can be reused, while the flexible bag 6 , the filling and dispensing head 10 and the flexible line 17 , together with the shut-off valve 19 , can be designed for a single use and can be thrown away or recycled after use. For further details of the drinks dispensing device 2 , reference is made to international patent application PCT/NL99/00454, in the name of the applicant, the content of which application is incorporated in the present application by way of reference.
FIG. 2 shows an embodiment of a drinks dispensing device 25 which is particularly suitable for use in catering establishments. The dispensing device 25 comprises a cooled compartment, or refrigerator, 26 in which there is a container 27 holding a carbonated drink. The container 27 may comprise a double-walled package with a rigid outer enclosure in which there is a flexible bag as shown in FIG. 1 , but may also comprise a metal container, such as a stainless-steel beer barrel which is known per se. The volume of the container 27 may vary from a few liters to 50 litres or more. A compressor or CO 2 cartridge 36 is connected to the container 27 . Furthermore, as an alternative to a compressor or CO 2 cartridge, it is possible for a cartridge containing carbon and CO 2 to be positioned in the container 27 for the purpose of generating the desired pressure, as described in international patent application PCT/NL/99/00144. The container 27 is connected, via a flexible plastic dispensing line 28 , to a dispensing head 29 . The dispensing head 29 forms part of a tap pillar 30 which is attached to the counter of a bar 31 . A shut-off valve 32 according to the present invention is fitted at the outlet end of the flexible line 28 which valve can be opened and closed by means of handle 33 at the end of the tap pillar 30 .
A cooling element (not shown in more detail), which cools the air which is present in the refrigerator 2 , to, for example, 5° C.–10° C., is accommodated in the interior of the refrigerator 26 . A fan 34 is used to suck warm air out of the hollow tap pillar 30 back to the refrigerator 26 . As a result of the partial vacuum which occurs as a result in the dispensing head 29 , cold air is passed from the refrigerator 26 , via a guide tube 35 in which the flexible dispensing line 28 is accommodated and which opens out in the dispensing head 29 , through the guide tube 35 and along the dispensing line 28 . As a result, the drink is cooled to, for example, 8° C. The device described above is shown in more detail in Dutch patent application 1015359, which was filed on 31 May 2000 in the name of the applicant, bearing the title “Tap device and container therefor, and method for its production”.
FIG. 3 shows a longitudinal section through the dispensing head 29 shown in FIG. 2 . The handle 33 is connected to the housing 43 in such a manner that it can rotate about a pin 40 , and acts via a spring 57 and projection 57 ′ on actuating member 45 for the purpose of opening and closing the shut-off valve 32 . The free travel of the handle 33 can be set by the positioning of projection 57 ′ with respect to the actuating member 45 . In the position shown in FIG. 3 , the projection 57 ′ acts directly on the actuating member 45 , so that the shut-off valve 32 is opened and closed with a small displacement of the handle 33 . Exchanging the projection 57 ′ for a projection 57 ′ which lies further to the right compared to the projection shown in FIG. 3 will allow the handle 33 a longer free travel before it acts on the actuating member 45 . As a result, it is possible to achieve complete opening and closure of shut-off valve 32 with a long travel, such as 90°, of the handle 33 . By simply exchanging the projection 57 ′, it is possible to adjust the travel of the handle 33 between the relatively short travel (for example 10°), as shown in FIG. 3 , and a relatively long travel, such as 90°.
The spring 57 allows a certain movement of the handle 33 without causing displacement of the actuating member 45 , and play is eliminated from the rotation of the handle about the pin 40 .
An outlet end 41 of the flexible dispensing line 28 , which is guided along a curved section through the dispensing head 29 , is accommodated in the seat 42 of the dispensing head. The outlet end 41 , which is made from rigid plastic, is provided with a circumferential slot 52 in which an edge 53 of the seat 42 of the dispensing head 29 engages in order to securely hold the outlet end 41 .
The dispensing head 29 comprises a fixed bottom part of the housing 43 , to which a cover 44 is connected so that it can execute a hinged movement between a closed position and an open position, in which the outlet end 41 and the shut-off valve 32 of the line 28 can be placed in the dispensing head 29 .
The actuating member 45 comprises a substantially horizontal arm 46 which, by means of a first end, is pivotably connected to a pin 48 . The flexible dispensing line 28 is positioned, via a guide 49 attached to the top side of the actuating member 45 , in a curved path against a curved end 46 ′ of the actuating member 45 .
Coupling means of the shut-off valve 32 , which are formed, for example, by a flange 51 on a slidable sleeve 61 , are connected to a coupling member at the end of the curved end 46 ′ of the arm 46 . The coupling member may suitably be designed as a fork 63 which engages behind the flange 51 of the shut-off valve 32 .
FIG. 4 shows the pin 40 attached to the handle 33 for moving the actuating member 45 . The pin 40 is provided on one side with a spring pawl 47 which, at its end, bears a tooth 38 ′ which runs at right angles to the pin 40 . The hinged cover 44 of the dispensing head 29 comprises a complementary tooth 38 which engages behind the tooth of the spring pawl 47 . In the upright position of the handle 33 , in which the shut-off valve 32 is closed, an unlocking projection 39 , which is likewise connected to the pin 40 , is positioned in such a manner that spring pawl 47 can be depressed, the tooth 38 ′ engaging in the receiving cavity in the unlocking projection 39 . This position is shown in FIG. 4 , so that with a closed shut-off valve 32 and an upright handle 33 , the cover 44 can be released from the bottom part of the housing 43 and can hinge open about hinge pin 60 .
As can be seen from FIG. 5 the grip 51 ′ of handle 33 is accommodated removably inside a cut-out in the wall of two concentric annular sleeves 55 , 56 . As a result of the sleeve 56 being rotated about its centre axis with respect to the sleeve 55 , or as a result of the sleeve 56 being omitted altogether, it is possible to adjust the travel of the handle 33 between, for example, 90° and 10° by making the openings in the walls of the rings 55 , 56 coincide or by positioning them in offset positions.
On the top side of the actuating member 45 there is a stop 58 against which, when the dispensing line 28 is being introduced into the dispensing head 29 via the guide sleeve 35 shown in FIG. 2 , the shut-off valve 32 comes into contact, thus preventing the shut-off valve 32 from being pushed through too far until it lies outside the dispensing head 29 .
Furthermore, FIG. 5 shows a spring element 51 ″ which is connected to the cover 44 , in order, in the event of actuation of the spring pawl 47 and unlocking of the cover 44 , to move the cover into the raised position.
It is clear from FIG. 5 that the end 46 ′ of the actuating member 45 is in the shape of a curved saddle which guides the flexible line 28 from a horizontal position to a substantially vertical position without kinking or sharp bends, this saddle ending in a fork 63 in which the flange 51 of the inner sleeve 61 of the shut-off valve 32 can be positioned. A separate clamping spring 62 is arranged in the seat 42 as a separate component, in order to position the shut-off valve 32 so that it is clamped with respect to the seat 42 when the cover is open, so that the cover 44 can be closed. In this case, the edge 53 on the seat 42 and the circumferential slot 52 of the outlet end 41 form a relatively airtight closure, thus preventing air from being sucked past the outlet end 41 into the cooled tap pillar 30 .
When the dispensing line 28 , which on account of its rigidity can push the shut-off valve 32 and the outlet end 41 through the guide tube 35 , is being introduced and pulled out, the closed shut-off valve 32 prevents beer from leaking into the guide tube 35 . When the shut-off valve 32 is being introduced into, or removed from, the fork 63 , the innermost sleeve 61 is therefore positioned in its retracted position, so that the shut-off valve 32 is closed. By using the dispensing head 29 in combination with the flexible dispensing hose 28 , which is provided with shut-off valve 32 in the vicinity of the outlet end 41 , it is possible for the dispensing line 28 to be positioned quickly and easily, so that an empty container of carbonated drink can easily be replaced by a full container. Since, in the process, the entire dispensing line 28 is also replaced, it is possible to eliminate frequent cleaning of the dispensing line, which, in particular for beer taps, involves considerable time and expense.
FIGS. 6 and 7 show an embodiment of a dispensing head 90 and dispensing line 101 for use in a dispensing device as shown in FIG. 1 . The dispensing head 90 comprises base part 91 with the handle 93 attached to it, together with a connecting member 91 ′ which lies transversely to the handle. The base part 91 is provided with a bore 96 and a receiving tube 92 for receiving a right-angled outlet end 103 of the flexible dispensing line 101 . The base part 91 is also provided with a receiving part 97 for receiving the flexible dispensing line 101 and the shut-off valve 102 , and with an actuating member or guide 98 , which can be moved in the axial direction along the receiving part 97 and is connected to the handle 93 for actuating the shut-off valve 102 of the dispensing line 101 . The guide 98 may be designed in the same way as the fork 63 which is shown in FIG. 5 and acts on the flange 105 of the innermost sleeve 107 of the shut-off valve 102 in FIG. 7 .
Furthermore, the dispensing head 90 is provided with a top part 95 which is connected to base part 91 in such a manner that it can execute a hinged movement about a hinge axis 96 ′. The top part 95 comprises a chamber 99 for accommodating a plate 104 at the end of dispensing line 101 . The plate 104 of a dispensing line 101 which has been placed in the dispensing head 90 is visible via an opening or window 100 , so that the contents of the drinks dispensing device can be established. The window 100 may have a curved and therefore enlarging form.
FIG. 7 shows the assembled dispensing head of the type shown in FIG. 6 . The shut-off valve 102 is connected to the outlet end 103 which lies at right angles thereto and is positioned in the bore 96 in the dispensing head 90 . Furthermore, the plate 104 of the outlet end 103 is provided with visual symbols so that it is possible to establish the type of carbonated drink when the plate 104 is positioned in the chamber 99 of the dispensing head. Consequently, an accurately defined position of the outlet end 106 is ensured after the top part 95 has been hinged shut, resulting in a favourable tap performance. Furthermore, the handle 93 is provided with a socket-head screw 110 for releasable connection to the base part 91 .
Finally, FIG. 8 shows an embodiment in which the handle 112 can be releasably connected, via a screwthread 113 and O-ring 114 , to a bore 115 at the end of the pin 116 . After the handle 112 has been removed, the pin 116 can no longer be rotated, or at least can only be rotated with great difficulty, by hand, so that it is no longer possible for children to get the drink dispensed. It is also possible for the handle 112 to be replaced by a similar type of handle with a different appearance, for example with a top part 117 which is made from stainless steel, chromium, plastic, wood, etc.
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A drinks dispensing device ( 1, 25 ) is provided with a cooling chamber and a tap head for receiving a shut-off valve ( 32 ) of a drinks container which has been positioned in the cooling chamber. The tap head comprises a displacement member ( 45 ) and a seat ( 42 ) which is connected thereto. A handle ( 33 ) is removably connected to the seat and can be removed therefrom. Without the handle ( 33 ), it is difficult or impossible for the displacement member ( 45 ) to be moved by a user by hand, and consequently the drinks dispensing device cannot be operated by children. It is also possible for the user to exchange the handle for a handle of a specific appearance which matches the interior or is distributed by the producer of the drink which is to be dispensed in the event of promotional activities.
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BACKGROUND OF THE INVENTION
I. Field of the Invention
The invention relates to a motor vehicle power train with a hybrid, electric and combustion, drive comprising two drive units, one an electric motor and the other a combustion engine, operating mainly in combustion mode.
More specifically, the subject of the invention is a hybrid motor vehicle power train operating in combustion mode or in electric mode, of the type comprising a combustion engine coupled to a gearbox via a clutch, and an electric machine.
II. Description of Related Art
Various ways of arranging an electric machine in a hybrid power train are known.
In one known arrangement, illustrated in particular by the publications FR 2 822 109 and FR 2 837 429, the stator of the electric machine can be fixed to the gearbox housing, itself secured to the housing of the combustion engine, while the rotor is connected to the planet pinion of a planetary gear train.
In another known arrangement, in particular that known from publication EP 1 232 890, the electric machine can be placed in a lateral position of the gearbox, the electric machine then being permanently connected to the secondary shaft by a chain and a pair of wheels added to the end of the primary and secondary shafts.
The disadvantage with these known arrangements is the additional axial bulk of the power train, which cannot be made compatible with transverse installations without difficulty.
BRIEF SUMMARY OF THE INVENTION
To overcome this disadvantage, the invention proposes that the electric machine is permanently connected to the primary shaft of the gearbox, preferably by a chain, and offset laterally with respect to the combustion engine.
It also proposes that:
with the vehicle stopped, the combustion engine is started by putting the gearbox in the neutral position and by closing the clutch for coupling the crankshaft and the input shaft of the gearbox, that with the vehicle running in electric mode, the combustion engine is started by closing the clutch for coupling the crankshaft and the input shaft of the gearbox, that the power train has a main combustion operating mode, the electric machine then performing the functions of alternator, of motor for applying extra torque at the low speeds of the combustion engine, and of an electric brake when slowing down, that the power train has an electric operating mode, the clutch for coupling the crankshaft and the input shaft of the gearbox then being open, and the electric machine then being able to propel the vehicle forward in the first and second gear ratios of the gearbox and in reverse by reversing the direction of rotation, in the second gear ratio, and that the gearbox is robotized.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the invention will become clearly apparent on reading the detailed description given below of an embodiment which does not limit the invention, with reference to the appended drawings, in which:
FIG. 1 is an axial overview of the proposed power train, without the combustion engine, and
FIG. 2 is a partial cross section thereof.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the whole of the power train 10 . The combustion engine 20 is represented by way of the nose of the crankshaft, to which is fastened a damping flywheel 30 composed of an actual flywheel 31 , of a vibration damper 32 and of a damping device 33 , corresponding, for example, to publication FR 2 833 329.
The combustion engine is coupled via splines 32 a of the damper to a gearbox 100 which is composed of a clutch and differential housing 110 and of a mechanism housing 120 . The clutch housing comprises a first compartment 111 closed by a flange 112 and containing a conical clutch 113 , the entry cone 114 of which is connected to the damper 32 , like the one disclosed in publication EP 1 318 319. The clutch is opened and closed by way of the bearing 116 . The upper ring 115 of the clutch 113 is connected to the input or primary shaft of the gearbox 100 via a hub 131 .
Situated from right to left on the primary shaft 130 are a first fixed drive wheel 132 of the electric machine 200 , a fixed toothing 133 of the first gear ratio, a first freely rotating pinion 134 of the fifth gear ratio, a second freely rotating pinion 135 of the third gear ratio, a third freely rotating pinion 136 of the fourth gear ratio, and a fourth freely rotating pinion 137 of the second gear ratio. These freely rotating pinions can be secured individually with the primary shaft by means of identical coupling devices 138 , for example “conical couplers” of the type proposed by publication FR 2 821 652. The fixed and freely rotating pinions of the primary shaft mesh with a freely rotating pinion and with fixed pinions borne by the secondary shaft 140 , namely, from right to left, a freely rotating pinion 141 of the first gear ratio, a first fixed pinion 142 of the fifth gear ratio, a second fixed pinion 143 of the third gear ratio, a third fixed pinion 144 of the fourth gear ratio, and a fourth fixed pinion 145 of the second gear ratio.
The freely rotating pinion 141 of the first gear ratio can be secured with the secondary shaft 140 via a free wheel 146 , according to an arrangement illustrated by publication EP 1 273 825, and via a conventional synchronizing and dog-clutching device 147 . Finally, the secondary shaft bears a fixed toothing 148 for transmitting movement to a conventional differential 150 .
The electric machine 200 , borne by the clutch housing 110 , drives a shaft 201 having a single fixed toothing 202 connected to the primary shaft 130 by a chain 203 .
FIG. 2 shows the control system and the relative position of the electric machine 200 . The control system is borne by the mechanism housing. This figure is a partial cross section of the gearbox 100 and shows a first electromechanical actuator 210 (as described, for example, in publication EP 1 229 274) in an upper position, the finger 211 of which can cooperate with a first dog sleeve 220 for controlling the coupling devices 138 of the freely rotating pinions 134 and 135 of the third and fifth gear ratios, via a first fork 221 , or with a second dog sleeve 230 for controlling the input clutch 113 via a second fork 231 .
The control system comprises a second electromechanical actuator 212 , in a lateral position, the finger 213 of which can cooperate with a dog sleeve 240 for controlling the coupling devices 138 of the freely rotating pinions 136 and 137 of the second and fourth gear ratios, via a fork 241 . Finally, a manual control device 250 allows the finger 251 to cooperate with the dog sleeve 260 for engaging the first and reverse gear ratio, via the fork 252 .
According to the invention, the figures show the specific position of the electric machine 200 laterally with respect to the engine and substantially at the usual location of the starter, this arrangement thus not increasing the length of the power train 10 .
FIG. 2 shows the compatibility of the control device, of the spindles of the forks 221 , 231 , 241 and of the actuators with the connection by the chain 203 of the electric machine 200 and the primary shaft 130 of the gearbox 100 .
FIG. 1 shows the absence of a device for reverse operation. The fixed pinion for reversing is advantageously replaced on the primary shaft 130 by the fixed drive wheel 132 of the electric machine 200 . Thus, according to the invention, the drive system of the electric machine, consisting of the wheels 132 , 202 and of the chain 203 , does not increase the length of the gearbox 100 and, therefore, does not increase the length of the power train 10 .
According to the invention, the electric machine is permanently connected to the primary shaft 130 of the gearbox 100 . It is therefore possible to use the electric machine:
as a starter, provided that the gearbox is in neutral and the clutch 113 is closed, as an alternator when the vehicle is stopped, provided that the gearbox is in neutral and the clutch 113 is closed, as a booster when running at whatever gearbox ratio to impart additional torque to the combustion engine at low speeds, as an energy recovery means for the slowing of the vehicle in any gearbox ratios, apart from the first gear ratio, in electric drive mode, with the combustion engine rotating or stopped, in reverse operation when reversing the direction of rotation of the electric machine 200 and by using the second gear ratio 137 , 145 coupled by the device 138 activated by the lateral actuator 212 , since the upper actuator 210 keeps the clutch 113 open in order to disengage the combustion engine 20 , in electric drive mode, with the combustion engine rotating or stopped, in forward operation by using the first gear ratio 133 , 141 or second gear ratio 137 , 145 coupled by the device 138 activated by the lateral actuator 212 , since the upper actuator 210 keeps the clutch 113 open in order to disengage the combustion engine 20 : the electric machine is thus able to propel the vehicle in forward operation in the first and second gear ratios of the gearbox, and in reverse operation by reversing the direction of rotation, in the second gear ratio, and in electric drive mode, to start the combustion engine by closing the clutch 113 so as to use the energy of the electric machine or the kinetic energy of the vehicle.
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A hybrid motor vehicle power train operating in thermal mode or electric mode includes a thermal engine coupled to a gearbox via a clutch and an electrical machine. The electrical machine is continuously connected to the input shaft of the gearbox.
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BACKGROUND OF THE INVENTION
The major commercial route to high strength, high modulus carbon fiber is based on polyacrylonitrile precursors. Such fibers, which are useful as reinforcing elements, are generally prepared by heating the polyacrylonitrile fiber in an oxidizing atmosphere at 200° to 400° C. so as to form a cyclized structure in the fiber and then carbonizing the oxidatively cyclized structure at a higher temperature, generally above 800° C. Increase in density is considered a good qualitative measure of cyclization (see Density Changes in Acrylic Fibers by Thermal Stabilization, Takaku et al, Sen i Gakkaishi, 38 (9), 82-8 (1982) and Carbon Work at the Royal Aircraft Establishment, W. Watt, Carbon 1972, 10, 121-143). The oxidative cyclization step is highly exothermic and releases ≧400 Joules/g of heat rapidly. If not controlled, this leads to deorientation and/or melting of the polyacrylonitrile fiber and results in low tensile properties in both stabilized and carbonized fiber. Improvements in control of this heat flux have been described in U.S. Pat. No. 4,336,022, wherein it is accomplished by use of ammonium sulfonate comonomers. Further improvements in control of heat evolution on oxidation are desirable and result from the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a typical Differential Scanning Calorimetry (DSC) scan for a 96/4 mol ratio poly(acrylonitrile-co-sodium styrene sulfonate) fiber.
FIG. 2 is a DSC scan showing the improvement obtained by exchanging the sodium counterions of the fiber of FIG. 1 for ammonium ions (as taught in U.S. Pat. No. 4,336,022).
FIG. 3 is a DSC scan showing the improvement effected by an ammonium bromide treatment in accordance with the invention.
FIG. 4 is a DSC scan which shows that ammonium chloride gives no improvement as compared to ammonium bromide (FIG. 3).
FIG. 5 shows measurement of Heat Flux Index on a DSC scan.
FIG. 6 shows tensile properties of carbonized fibers whose precursors had been treated with a number of different compounds prior to cyclization as described in Example 7.
SUMMARY OF THE INVENTION
The present improved process involves heating a polyacrylonitrile fiber which has been impregnated with a compound selected from the group consisting of ammonium sulfamate, ammonium bromide and ammonium iodide in an oxidizing atmosphere at 200° C.-400° C. to form a cyclized structure in the fiber and then carbonizing the fiber by heating in a non-oxidizing atmosphere at a temperature above 800° C.
DETAILED DESCRIPTION OF THE INVENTION
The precursor fibers useful for treatment in accordance with the invention are acrylonitrile fibers including 100% polyacrylonitrile. Preferred acrylonitrile fibers contain sulfonic acid comonomers or their salts such as the sodium or ammonium salts, especially ammonium salts. Illustrative polymers are poly(acrylonitrile-co-ammonium styrene sulfonate), poly(acrylonitrile-co-ammonium methallyl sulfonate) and poly(acrylonitrile-co-ammonium acrylamidomethyl propanesulfonate).
The ammonium compounds which are effective in controlling the heat efflux from the acrylonitrile polymers are ammonium salts of certain inorganic acids, specifically ammonium sulfamate, bromide and iodide. The chloride and sulfate are not satisfactory. The salts can be applied by padding or any other convenient method.
As mentioned above, the useful salts provide a more gradual, controlled rate of heat evolution during oxidative stabilization which results in higher tensile properties after carbonization. This effect can be observed and measured. Furthermore, because the heat evolution is spread out over a wider temperature range, a faster range of stabilization is possible, thereby providing an important advantage over prior art processes. After the precursor fibers are impregnated with the selected ammonium salt, they are heated in an oxidizing atmosphere at temperatures generally in the range of 200° to 400° C. The oxidizing atmosphere is preferably air.
In general, sufficient cyclization has been achieved when the fibers reach a density of at least 1.35 g/cm 3 . The precursor fibers usually have a density of about 1.18 g/cm 3 . The cyclized intermediate fibers may be converted to carbon or graphite fibers by methods known in the art, e.g., heating the intermediate fibers in an inert gas at 800° to 1500° C. or higher for a short period of time. Carbon fibers will have a density of at least 1.70 g/cm 3 . In the carbonization step, the atmosphere must be non-oxidizing. Nitrogen or argon are preferred media. The cyclization of the fiber is usually carried out at constant fiber length or slight draw by application of tension as is known in the art.
Thermal cyclization of acrylic fiber becomes runaway unless slow heating rates are employed. The present invention allows faster cyclization to be achieved by use of selected ammonium salts which reduce the heat surges.
TEST PROCEDURES
Differential Scanning Calorimetry: A thermal analyzer (Du Pont 1090 Thermal Analyzer) is used to provide the DSC scans. In each case, a measured weight of fiber was inserted in the sample holder sealed in air, and heated under a flow of nitrogen at the rate indicated in the figures. The rate of heat evolution is recorded at the various temperatures. The sample weights were normalized to permit comparison.
Heat Flux Index: Refer to FIG. 5. A base line is drawn for the DSC scan and the height of the highest peak of heat flux above the base line is measured. The sides of the highest peak are extended to the base line and the line segment of the base line intersected by these extensions constitute the peak width. The ratio of one half peak height (a in FIG. 5) to peak width at half peak height (b in FIG. 5) is the Heat Flux Index (HFI). The smaller the HFI, the more efficient the heat spread, provided of course that the same size sample, rate of heating and other conditions are comparable. This technique provides a convenient way to measure the efficacy of heat efflux control.
Tensile Properties are measured on 1" filament samples tested at 10% strain rate on an Instron® tensile tester. Density determinations are made in calibrated density gradient tubes as known in the art.
EXAMPLE 1
Samples of (a) polyacrylonitrile, (b) poly(acrylonitrile-co-methylvinyl ketone) (90/10 mole ratio), (c) poly(acrylonitrile-co-sodium styrene sulfonate (96/4 mole ratio), and (d) poly(acrylonitrile-co-acrylamido methylpropane ammonium sulfonate) (96/4 mole ratio) fibers were soaked in 1% ammonium sulfamate for 1 hour and then air dried. The samples together with water treated controls were suspended in a hot air oven under ˜5 mg/denier tension and heated to 250° C. and held at 250° C. for 1 hour. Samples were cooled and density measured. Results below show higher densities for the ammonium sulfamate treated samples.
______________________________________ Density a b c d______________________________________water control 1.3006 1.3026 1.3010 1.3529ammonium sulfamate 1.3406 1.3167 1.3724 1.3731______________________________________
EXAMPLE 2
Samples of 100% polyacrylonitrile fiber were padded with 1% aqueous ammonium sulfamate by passing round a 4" diameter feed roll partially immersed in the ammonium sulfamate solution and then passed at constant length directly into a series of three 18" Lindberg Hevi-Duty ovens at 250°-280°-300° C. Traverse through the ovens was 60 minutes. Density of the ammonium sulfamate-treated sample was 1.4067 whereas that of a water-treated control was 1.3737. Repeating with a 30 minute traverse gave densities of 1.3361 for the sulfamate sample and 1.3000 for the control.
Examples 1 and 2 show that higher density values are achieved in the cyclization step in equal processing times and conditions when the ammonium sulfamate is employed as compared to controls.
EXAMPLE 3
Acrylonitrile/sodium styrenesulfonate (96/4 mol %) yarn was traversed through three 18" Lindberg Hevi-Duty ovens at 250°, 280° and 300° C. with a 10 minute residence time in air using a 1.2 X draw ratio. Prior to entering the first oven the yarn was passed over a feed roll (3-4 wraps) partially immersed in aqueous ammonium sulfamate of 0, 0.5, 1.0, 2.0, 5.0% concentration. The stabilized fibers were then carbonized by winding on graphite holders (the fiber is relatively loose in the holder) and heating in nitrogen to 997° C. over 1 hour, maintaining at 997° C. for 1 hour and cooling to room temperature over 5 hours. Results are shown below.
______________________________________ 1" Filament Tensiles% Ammonium Stabilized Fiber Carbonized T/E/M.sub.iSulfamate Density Density gpd______________________________________0 1.3243 -- 5.0/0.9/5490.5 1.3365 -- 3.9/0.8/5081 1 3518 1.7598 26/2.6/8722 1.3573 1.7836 29/2.5/10385 1.3651 1.8498 3.6/0.9/502______________________________________
It is obvious that the more controlled cyclization promoted by the ammonium sulfamate leads to significantly higher tensile properties. The drop-off in properties at the 5% ammonium sulfamate concentration is due to fiber sticking believed caused by the presence of too much salt as indicated by the abnormally high carbonized density.
EXAMPLE 4
The copolymer of acrylonitrile/sodium styrenesulfonate (96/4 mole ratio) was treated with 1% aqueous solutions of the following salts, dried and then the Heat Flux Index determined as described previously. Results are shown below.
______________________________________ HFI______________________________________Control - no catalyst 0.8-1.01% ammonium iodide 0.011% ammonium sulfide 3.01% tetraethyl ammonium bromide 0.61% tetramethyl ammonium iodide 0.51% anthraquinone ammonium sulfonate 0.9______________________________________
EXAMPLE 5
A dried fiber copolymer of acrylonitrile/sodium styrene-sulfonate (96/4 mole ratio) in which the sodium ion had been replaced by ammonium via acidification with sulfuric acid, followed by water washing and neutralization with ammonia was soaked for 1 hour in 1% aqueous solutions of the following potential catalysts, then dried and the Heat Flux Index measured as described previously. Results are shown below.
______________________________________ HFI______________________________________Control - no catalyst 0.041% ammonium iodide 0.011% tetramethyl ammonium iodide 0.021% ammonium chloride 0.041% ammonium fluoroborate 0.031% ammonium carbonate 0.601% tetraethyl ammonium bromide 0.031% ammonium chromotropate 0.041% ammonium formate 0.02______________________________________
EXAMPLE 6
A sample of a commercial acrylic fiber poly(acrylonitrile-co-methylacrylate/co-itaconic acid ˜97/2/1 mole ratio) was treated with 1% aqueous ammonium iodide, dried and then the Heat Flux Index measured. The result was 0.03 whereas an untreated control gave 0.9.
Examples 3-6 show that better control of heat efflux is achieved during cyclization with use of the ammonium salts of strong acids as described above.
EXAMPLE 7
A control sample of poly(acrylonitrile-co-sodium styrene sulfonate) was ammoniated by soaking skeins of the fiber in 1N H 2 SO 4 for 1 hour, rinsing with distilled water, soaking in 1N NH 4 OH for 1 hour, rinsing with distilled water and air drying. Test samples were treated similarly except that they were soaked for 1 hour in either 1% aqueous ammonium iodide, ammonium formate, ammonium sulfamate or ammonium selenate prior to drying. Samples of test and control fiber were passed through 3 Lindberg ovens (18" each) in air, at 260°-280°-300° C. The rate of windup to feed rate was 1.2 X. The yarns were passed through the ovens in different experiments with total residence times of 15-60 minutes.
The stabilized yarns were then passed through a 36" Lindberg oven, set at 1150° C. and blanketted well with nitrogen to avoid oxidation. Total residence time in this oven was 15 minutes. Tensile property results for 1" filaments of the resulting carbon fibers are shown in FIG. 6. These show that the ammonium iodide treatment results in carbon fiber with higher tensile properties.
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Improved process for producing a carbon fiber having high tensile strength and high modulus involves oxidation of acrylonitrile fiber which has been treated with selected ammonium salts, from the group of ammonium sulfamate, ammonium bromide and ammonium iodide.
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This application is a division of application Ser. No. 09/056,096, filed Apr. 7, 1998 and hereby incorporated by reference herein.
FIELD OF THE INVENTION
The present invention is directed to communication network access architectures and particularly relates to reducing the complexity of Optical Network Units (ONUs) in a Fiber-In-The-Loop (FITL) architecture by repartitioning some of the functionality to other elements of the network.
BACKGROUND OF THE INVENTION
In order to provide a communications network with the capability to accommodate current and future high bandwidth (broadband) services, optical fiber is being extended deeper into the network, towards the end user. The final link to homes or businesses in present-day systems is often still part of the installed distribution infrastructure, comprised mainly of twisted pairs of copper wire arranged in a topology of distribution cables and drop lines. For high-bandwidth applications, signal loss along a twisted pair increases with frequency and so the length of the twisted pairs must be kept small, leading to deeper penetration of the fiber.
In fact, it is known that the loss in decibels is nonlinearly related to the frequency of measurement (raised to the power 0.5 to 0.7, depending on the frequency and the type of cable) and hence a cable with a loss of, for example, 20 dB at 1 MHZ would have a loss of at least 28 dB at 2 MHZ, and at least 40 dB at 4 MHZ. Moreover, the signal loss in a twisted pair is also proportional to its length. It has been found that if the twisted pair is intercepted at a distance close enough to the end user so that high bit rates (on the order of 25 Megabits per second (Mbps)) can be successfully delivered, then, depending upon the complexity of the loop transmission equipment, the loop must be shortened so as to have a length of at most approximately 500 to 3,000 feet.
This upper bound on loop length has led to the development of new access architectures, known in the art as Fiber-To-The-Cabinet (FTTCab), Fiber-To-The-Neighbourhood (FTTN), Fiber-To-The-Curb (FTTC) or Fiber-To-The-Building (FTTB), all generically referred to as Fiber-In-The-Loop (FITL). The FTTC architecture has been the method of choice when considering the delivery of broadband services to a residential area consisting of single-family dwellings.
Traditional FITL implementations provide a system in which a Host Digital Terminal (HDT) controls the FITL network and is located at, say, a central office. The HDT is connected on one side to core network resources and on another side (the “access side”) to a series of dependent Optical Network Units (ONUs) via a fiber-based link in the form of a Passive Optical Network (PON), a Synchronous Optical Network (SONET) ring or a number of point-to-point links. Finally, the ONUs communicate bidirectional data with the individual end users along the final (short) stretches of copper.
At such short maximum loop lengths of only a few hundred feet, the number of subscribers that can be served by a single ONU is rather limited. Therefore, the ONU must be small, simple and inexpensive for the service provider to buy and install so that its initial cost can be borne by the revenues from the small number of subscribers that the ONU serves. Furthermore, having only a small group of subscribers served by any one ONU requires that a very large number of ONUs be deployed to create a ubiquitous access network. This demands that the ONUs, once installed, be individually very cheap to maintain while allowing for future changes in subscriber service requirements. Since the ONUs are placed deep in the “outside plant”, any requirement which causes these ONUs to be visited, either for repair purposes or for provisioning different subscriber services (by changing line card functionality), will result in a system that is too costly to operate.
Conventional prior art FITL architectures, FTTC in particular, have adopted the approach of installing shelves or frames of equipment, including service-specific line cards, in a protective housing on the curbside. Such ONUs are large, complex and require regular visits, in order both to modify services by changing line card types and to repair the units, since more complex ONUs are more likely to fail. Hence, the cost of deploying an array of service-specific line cards is prohibitively high in terms of capital cost (complex electronics, large cabinets) and also in terms of operating costs due to the need to visit the ONU so as to implement a service type change by replacing the line card type. Furthermore, installing cabinet-mounted equipment is often complicated by the unavailability of acceptable locations in residential areas. This becomes more critical as the loop length is shortened and ONU size is reduced to the point where ONUs are installed within subdivisions and not at their edges.
An alternative prior art approach consists of replacing the service-specific line cards with (somewhat more expensive) service-independent line cards that can be configured in software. These are primarily based upon the use of wideband analog front-end loop drivers, oversampling codecs, bit-rate-reduction (decimator) blocks and digital filtering components, also known as Digital Signal Processor Application-Specific Integrated Circuits (DSP ASICs). This combination of functions allows the service-specific functions of the line card to be implemented in software, which can be downloaded to the ONU from the HDT, thereby eliminating the need to visit the ONU to change the service type delivered to a subscriber.
This solution, also referred to as Service-Adaptive Access (SAA), has been adopted by Nortel in the development of its S/DMS Access Node, which can be deployed in a FTTC or FTTCab configuration. The ONU, also called an RDT (Remote Digital Terminal), consists of an array of service-dependent line cards, or alternatively service-independent line cards based upon on-card DSP processing and each using a DSP dedicated to that card, or possibly (in order to control cost) a mix of both types of line cards, in addition to common equipment for multiplexing the digitized signals, a control processor and an optoelectronic transceiver. The number of different line card types can be reduced by replacing some or all of the standard POTS (Plain Old Telephone Service) cards with SAA line cards.
When data flows from the subscriber into the ONU, (known as the “upstream” path), the S/DMS Access Node samples the input analog signal arriving on the twisted pair and puts it into a standard digital format prior to transmission from the ONU to the HDT. In the opposite (“downstream”) direction, the ONU converts, for example, μ-law-encoded digital voice data into an analog format for delivery to a user's home. Unfortunately, the deployment of such ONUs, each comprising a set of service-independent line cards, has several serious drawbacks in the context of a FITL system with deep fiber penetration:
1) Cost
The DSP-based line card has a larger power consumption, complexity and failure rate, which translates into significantly higher system cost;
2) Size
The size of the ONUs has increased, making it more difficult to install them in locations close to the end user;
3) Complex Software Download
The ONU and access system at the HDT have to provide a high-integrity software download/verification path which requires a processor in each ONU for monitoring download integrity;
4) Initial Servicing
The functionality of the individual line cards is such that the ONU must be visited each time a new subscriber is to be accommodated. The SAA cards do not allow “future-proofing”, i.e. it is not possible to connect every loop to a line card (regardless of whether or not that loop was expected to go into service immediately) and then to remotely provision, or “initialize”, that loop;
5) Efficiency
The DSP is placed on the line card and as such is dedicated to a single loop. Furthermore, it has to be dimensioned for the most stringent expected processing demands that can be encountered in the loop. In combination, this leads to the number of high-performance DSPs deployed being equal to the number of lines served. Thus for many service types, including low-bandwidth POTS (the most common), each DSP may be operating at a fraction of its full capacity. However, this spare capacity cannot be shared across other loops, leading to an effective increase in power consumption and total system cost.
It is important to note that reducing the size of the ONU by reducing the number of DSP-based SAA line cards per ONU does little in the way of mitigating the above disadvantages. In fact, partitioning the equipment into smaller ONUs with lower line counts per ONU results in an increased overall complexity since the simplification achieved on a per-ONU basis is more than offset by the increased number of ONUs that have to be deployed. As the ONU line count falls, the overall complexity of the ONU population required to serve a particular area or group of subscribers rises and has deleterious consequences on the mean-time-between-failures (MTBF) of the ONU population, requiring a higher degree of maintenance activity. This translates into more frequent on-site visits (“truck rolls”) by the repair crew and requires more travelling to the increased number of ONU sites.
SUMMARY OF THE INVENTION
It is an object of the present invention to obviate or mitigate one or more disadvantages of the prior art.
The invention may be summarized according to a broad aspect as an optical network unit (ONU) for enabling communication between a plurality of subscriber loops and a host digital terminal (HDT), comprising a plurality of substantially identical line interface units (LIUs) for respectively interfacing to the plurality of subscriber loops and each having an oversampling codec; an optical transceiver for connection to the optical fiber; and a bidirectional multiplexer connected between the optical transceiver and the plurality of LIUs.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described with reference to the following drawings, in which:
FIGS. 1A and 1B show a block diagram illustrating a prior art FITL communications network;
FIGS. 1C and 1D show a block diagram showing a FITL communications network constructed in accordance with the present invention, including an exemplary inventive HDT and ONU;
FIG. 2A shows an exemplary data structure on the downstream fiber link of the prior art network of FIGS. 1A and 1B;
FIG. 2B illustrates upstream data flow on the fiber link of the prior art network of FIGS. 1A and 1B;
FIG. 3A shows an exemplary data structure on the downstream fiber link of the inventive network of FIGS. 1C and 1D;
FIG. 3B illustrates upstream data flow on the fiber link of the inventive network of FIGS. 1C and 1D; and
FIGS. 4A, 4 B and 4 C are detailed block diagrams illustrating three different embodiments of part of the HDT of FIGS. 1C and 1D in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Before the invention is described in detail the structure and function of the conventional prior art system of FIGS. 1A and 1B will be described.
With reference to FIGS. 1A and 1B, a fiber-based access system intended to provide FTTCab, FTTC or FTTB as part of a communications network consists of two main types of components, an HDT 1 and a plurality of ONUs 2 (only one of which is shown). Each ONU 2 has a plurality of Line Interface Units (LIUs) 3 , 27 connected to a bidirectional optical fiber distribution cable 4 via an intervening mux (multiplexer-demultiplexer) 5 , a PON out station (PON-OS) 28 , and an optical transceiver 6 .
A number of different ONUs in the same vicinity are grouped together by virtue of their associated distribution cables being joined together at a passive optical splitter 30 which is connected directly by means of an optical fiber umbilical 4 a to a transceiver 16 of the HDT 1 . There may be a plurality of groups of ONUs, each group being connected to the HDT through a respective optical fiber umbilical and transceiver. Prior art configurations for the fiber link between the HDT and the multiple ONUs include the PON configuration shown in FIG. 1A, a point-to-point connection between the HDT and each ONU, as well as ring configurations with an optical transport ring passing from the HDT through each of the ONUs in turn and returning to the HDT.
The HDT 1 further comprises a digital switch matrix 17 connected to the transceivers 16 , in addition to an operations, administration and maintenance (OAM) processor 18 , a control processor 19 and a signalling processor 20 , each of which are also connected to the digital switch matrix 17 . The OAM processor 18 includes a communication port 200 by which it can receive control, provisioning and configuration instructions from the management layer of the core network 23 as well as return the access system operational and maintenance status to the network management system. Finally, a plurality of transceiver blocks 21 are connected between the switch matrix 17 and the core network 23 .
Turning now to the structure of the ONU, each LIU 3 is connected on one side by a bidirectional signal path 23 to the mux 5 and on the other side to a respective subscriber loop 7 which is commonly a copper twisted pair. The LIU 3 performs the function of bidirectional communication of signals with the subscriber equipment in the appropriate analog format (e.g., 4 kHz voice for POTS, 2 B 1 Q line coded signals for ISDN—Integrated Service Digital Network) over the intervening twisted pair 7 ; the insertion of suitable loop currents by an Analog Front End (AFE) 8 ; and the superimposition of a ringing signal when required (and its rapid removal when the line conditions change to those of an “off-hook” phone) via a ringing generator 9 . The LIU 3 includes a loop status detector 10 to detect when the phone or other service is activated (this may include detecting modem tones or changes in d.c. (direct current) or a.c. (alternating current) conditions on the loop 7 .
The LIU 3 usually includes a wideband digital one-bit delta-sigma oversampling codec 11 able to provide adequate bandwidth and quantizing noise performance when converting signals between the analog and digital domains, a decimator 12 D which removes some of the excess upstream bandwidth from the oversampling codec 11 , and an inverse decimator (or “interpolator”) 12 ID for converting downstream words into a high-rate bit stream. The multi-bit words are fed into (read from) a service-specific processor 14 implemented as a digital signal processing (DSP) engine which converts the upstream (downstream) oversampled and decimated data on the subscriber side 22 of the DSP 14 to (from) a standard format data stream on the core network side 23 of the DSP 14 . For instance, data arriving from the subscriber may be converted, in stages, from a 4 kHz analog POTS signal on the loop 7 into an analog voice waveform (free of d.c. loop signalling) at the output 24 of the AFE 8 , then into a 1 Mbps one-bit delta-sigma encoded bit stream at the output 25 of codec 11 , subsequently into 32 kHz×20 bits/word linearly encoded samples at the output 22 of the decimator, and finally into an 8-bit μ-law pulse code modulation (PCM) signal at the output 23 of DSP 14 .
Typically, a service-specific Service Application Software (SAS) is downloaded from the HDT 1 under instructions from an OAM manager via the OAM processor 18 located in the HDT 1 , and stored in a service-specific SAS Random Access Memory (RAM) 15 associated with the DSP 14 . Each LIU 3 interfaces with one physical path to one subscriber, such that if a subscriber has two twisted pair drops to the subscriber's premises, then two LIUs, and hence two DSPs, are required.
As an alternative to the oversampling codec, decimator, service-specific processor and SAS downloaded to the SAS RAM 15 , a simple, fixed functional block such as a μ-law (or A-law) PCM codec or an ISDN 2 B 1 Q line driver/receiver and formatting block can be used. In these cases the LIU 3 would take on a fixed function and it would be necessary to visit the remote site of the ONU to physically change the LIU type in order to change the services delivered. This is both costly and time-consuming because the LIU is usually located in a small cabinet in an outside-plant location, and technical staff have to find the location of the ONU and drive to it before they can physically change the appropriate LIU.
An ONU 2 is implemented by assembly of an array of LIUs 3 in a card cage (or its equivalent) along with additional circuit packs for common equipment such as the mux 5 , the PON-OS 28 , the optical transceiver 6 and an ONU control processor 26 which receives and transmits ONU control commands from and to the HDT 1 . The Loop Status Detector 10 and Loop Status Processor 13 of the LIU 3 communicate loop-specific status and processing commands from the ONU control processor 26 to the ringing generator 9 . Not shown is a control link from the ONU control processor to the codec 11 for controlling its output and sampling rates.
The mux 5 may be implemented using time slots or packets. For this discussion, time division multiplexed (TDM) time slots will be assumed. The mux 5 has to accommodate differing final processed bandwidths on its signal paths 23 from each of the LIUs 3 and hence has to be programmable in bandwidth per port on its access (subscriber) side. For instance, a POTS circuit would occupy 64 kbps and hence would require one 8-bit word (time slot) every 125 μs (the standard frame period for TDM) for the information path. On the other hand, an ISDN circuit runs at 144 kbps, thus requiring three 8-bit time slots every 125 μs.
In addition, a form of signalling and control path between the HDT and ONU is required. This can be achieved in one of many known forms, such as common channel signalling with multiplexed signalling messages from all line cards flowing in a single signalling channel, channel associated signalling or even embedded tone signalling or bit-robbing.
The fiber optic links 4 , 4 a support a bidirectional transmission path over one or two fibers. Either two fibers with unidirectional operation of each fiber could be used, or alternatively optical signals could be propagated in both directions down a single fiber with optical carriers being of a different wavelength in each direction.
In the direction from the HDT 1 to the ONU 2 , the basic partitioning of the transmitted bandwidth from the HDT to each ONU is carried out by known means such as assembling the traffic information into a subframe of packets, cells or sequences of time slots. The subframe can also comprise control information as well as the ONU address. An example of a prior art format at the input to ONU 2 is shown in FIG. 2 A. Each 125 μs frame N sent down the umbilical 4 A comprises a plurality of subframes, each of which is addressed to a specific ONU. The subframe for ONU # 3 consists of an ONU address synchronisation field, a control field, a common channel multiplexed signalling field and a traffic field comprising T eight-bit time slots for the transmission of data.
The traffic, signalling and control fields, are multiplexed in one of many well known ways. One method is to allocate several time slots to the address field, then the first of two timeslots after the address field to a signalling channel and the other to a control channel. The signalling channel carries loop status information and instructions to and from a specific line card interface in a multiplexed format (e.g. Common Channel Signalling or Multiplexed Channel-Associated Signalling). The control channel carries ONU control information including SAS downloads as well as OAM status information.
The remainder of the payload time slots are used for multiplexed traffic data, which is in one or more 64 kb/s, 8-bit bytes (assuming a conventional 125 μs frame rate). Each service payload is in its final format as required at the access/core network interface. In the illustrated example, POTS occupies 1 time slot, ISDN takes up 3 time slots and DS- 1 occupies 25 timeslots, while the total number of traffic time slots is T=29. The demarcation boundaries between each subframe can be changed as long as the sum of the lengths of all packets, cells or sequences of timeslots does not exceed the frame length.
In the direction from the ONU 2 to the HDT 1 , each ONU transmits a burst of data, timed so that, when combined by the splitter 30 , the bursts of data from all the ONUs form a train of incoming bursts at the HDT end as shown in FIG. 2 B. The transmission protocol operates in TDM mode with HDT synchronization of ONU burst timing to avoid burst collision, which would otherwise result in one ONU overwriting another ONU's data in the upstream path. In this way, transmission path delay from each ONU can be measured. Pairs of upstream bursts on the umbilical are separated by “guard bands” to allow tolerance on the burst control loop. The structure of the individual subframes travelling in either direction is the same, although the inter-subframe assembly methods are different.
In the HDT 1 , the switch matrix 17 accepts TDM frames from transceiver 16 and, according to a mapping controlled by the control processor 19 , routes the individual time slots in each frame towards the appropriate transceiver 21 . Similarly, the switch matrix 17 accepts downstream data from the transceivers 21 , subdivides the data into traffic time slots that constitute a particular subframe that is routed to the appropriate ONU. This switch “fabric” also acts as a conduit to connect ONU signalling and control paths to the signalling, control and OAM processors 20 , 19 , 18 .
The signalling processor 20 formats the signals from the ONUs into a standard protocol (e.g., TR-303) to feed the network interfaces 21 (and vice versa), and formats the signalling messages to pass on subscriber-generated and access-generated messages to the core network 23 (and vice versa).
The control processor 19 controls the overall operation of the HDT and subtending ONUs, based on system status inputs and inputs from the OAM processor 18 and signalling processor 20 . For instance, the control processor 19 will manage the cross-connection map for the HDT switch matrix 17 .
It is noted that a key feature of the prior art system is the transmittal of fully formatted data across the fiber 4 , 4 a . The ONU 2 is responsible for producing an analog version of an oversampled digital signal based on a received downstream flow of, say, mu-law-encoded voice data. Similarly, the ONU 2 oversamples its subscriber input and formats it for upstream use by the HDT 1 . Clearly, the benefit of this technique lies in the bandwidth savings achieved by transmitting fully formatted data across the PON. However, the complexity of such ONUs leads to the previously discussed disadvantages in the areas of cost, size, software download complexity, initial servicing and efficiency.
It would instead be more desirable to place complex processing functions in the HDT 1 , by transmitting “raw” (unformatted) data across the PON. This is particularly feasible in today's era of fiber optic bandwidth abundance. Accordingly, the present invention is now described with reference to FIGS. 1C and 1D, in which an inventive fiber-based access system intended to provide FITL (especially FTTC) comprises an HDT 101 and a plurality of ONUs 102 (only one of which is shown). Each ONU 102 consists of an array of LIUs 103 , 127 along with a bidirectional mux 105 , an ONU control processor 126 , as well as a PON-OS 128 and an optoelectronic transceiver 6 . As in the prior art, the mux 105 is of the TDM type, comprising ports that are programmable so as to allot a selectable number of time slots (and hence, bandwidth) to each LIU in both directions of communication.
The mux 105 is connected to an oversampling codec 111 in each LIU 103 by a downstream line 153 and an upstream line 125 . Not shown is a control link from the ONU control processor to the codec for controlling its output and sampling rates. The codec 111 preferably comprises complementary one-bit sigma-delta analog-to-digital and digital-to-analog converters, and is connected to a wideband AFE, which interfaces directly with an analog drop line 7 leading to and from a subscriber. Preferably, the link from the fiber at the curb to the subscriber is formed by copper twisted pairs, although coaxial cable may be accommodated by the use of a suitable AFE 8 .
Each LIU further comprises a ringing generator 9 and a loop status detector 10 , which are connected to each other by line 147 , to the AFE 8 by respective lines 145 , 146 and to the mux by respective lines 133 , 134 . The ringing generator 9 adds a ringing signal to the line under control from signal 133 received from the mux 105 , and removes it when the loop status detector 10 determines that the line is in the off-hook position. The loop status detector 10 also provides a digital rendition of the analog line voltage on signal 134 connected to the mux 105 . It is to be understood that the ringing generator 9 and loop status detector 10 may be connected directly to the control processor 126 instead of to the mux 105 . Moreover, the mux 105 may itself be connected to the ONU control processor 126 .
Electrical communication between the mux 105 and the PON-OS 128 can be effected using a bidirectional link 135 or two unidirectional links. The ONU control processor 126 is connected to the PON-OS 128 by a bidirectional signal link 123 . The transceiver 6 serves to transform the (multiplexed) electronic data into an optical signal destined for the HDT, and to convert an optical signal from the HDT into electronic data used by the mux 105 . The optical signals in both directions preferably originate from, and are combined onto, a single fiber optic cable 4 .
Multiple optical fibers come together at a passive optical splitter 30 , which in the upstream direction adds the optical energy on each fiber and sends the resultant signal along an umbilical link 4 a to the HDT, and in the downstream direction splits the downstream optical signal on the fiber umbilical 4 a into a number of identical optical signals travelling along respective individual fibers 4 .
The HDT interfaces with the umbilicals ( 4 a as well as others not shown) by means of respective optoelectronic transceivers 16 connected to a digital switch matrix 117 . The switch matrix is conventional TDM digital switch with traffic data entered into sequential locations in a large data memory at a given fixed frame rate, and the same data read out again in a sequence controlled by a connection memory. The sequencing is controlled via a control link (not shown) by a control processor 119 in the HDT. The control processor 119 is preferably also connected to a loop status processor 113 , which performs functions such as decoding a telephone number dialled by the subscriber based on the sampled digital line voltage transmitted from the loop status detector 10 in each LIU 103 .
The HDT 101 further comprises a second switch matrix 131 , also a conventional TDM digital switch controlled by the control processor 119 , which is connected to a plurality of transceivers 21 that interface with the core network (not shown). Also connected to switch matrix 131 are a signalling processor 20 and an OAM processor 118 . As in the prior art, the signalling processor 20 formats outgoing data so that it is in the proper signalling format (e.g., TR-303) used by the core network, and vice versa. The OAM processor 118 provides the core network with status information via a link 200 ; this link also serves to relay instructions for configuring the mux 105 in the ONUs 102 . The control processor controls the overall operation of the HDT and subtending ONUs, based on inputs from the OAM processor 118 and the signalling processor 20 , as well as system status inputs.
The switch matrices 117 , 131 are connected by a bidirectional “hair pin” connection 132 and also through sets of DSPs. The connections are shown in greater detail in FIG. 4 B. The first bank of processors consists of a plurality of DSPs 114 X,Y,Z that process respective demultiplexed upstream signals 160 X,Y,Z and produce respective signals 170 X,Y,Z that are routed by switch matrix 131 . Decimators 130 X,Y,Z respectively intercept the upstream signals 160 X,Y,Z so that the associated DSPs are fed fixed-length words of data at a certain speed instead of an oversampled bit stream at a higher rate, as output by the codec in a given LIU.
The second set of processors joining the switch matrices 117 , 131 is a plurality of DSPs 114 A,B,C which process signals 161 A,B,C arriving from switch matrix 131 , forming signals 163 A,B,C. The DSPs 114 A,B,C are connected to respective interpolators 129 A,B,C, which create respective high-rate bit streams 164 A,B,C that are routed by switch matrix 117 .
Each DSP 114 X,Y,Z and 114 A,B,C is preprogrammed by application and data files stored in respective SAS RAMs 115 X,Y,Z and 115 A,B,C to execute a conversion algorithm that converts digital data from one format to another. The actual number of DSPs, decimators and interpolators required will depend on total system requirements.
The hair pin connection 132 serves to interconnect the two switch matrices 117 , 131 , should it be necessary to implement a complex conversion algorithm involving multiple processing steps executed by traversing the DSPs several times in sequence.
From the above, it can be seen that the structure of the inventive system differs from that of the prior art in that the ONUs have been simplified by migrating the DSP functionality to the HDT. As a result, instead of transmitting fully formatted data across the PON, only “raw” (unformatted) data at high bit rates is exchanged between the HDT 101 and ONU 102 (and others not shown) along the fibers 4 , 4 a . The high data rates required are easily achievable using commonly available optical fibers.
It is helpful to first describe the format of data travelling downstream from the HDT on the fiber 4 a with reference to FIG. 3A, which illustrates how a downstream frame F of 125/M μs (microseconds) is divided into subframes SF 1 -SF 5 destined for respective ONUs. The value of 125 μs is the standard length of a frame in the public switched telephone network (PSTN) and M is the factor by which this frame length is reduced, usually 1, 8, 12, 16, 24, 25 or 32. As will be shown hereunder, M is used in determining the so-called bandwidth granularity (BG), which is a measure of the resolution in bandwidth deliverable across the PON.
The relative size of a subframe, expressed as the number of BG units required to provide enough transport capacity for the corresponding ONU, may differ from one ONU to another. Considering a particular subframe SF 3 , it is shown as divided into four fields: an ONU address and synchronization field, a control field, a signalling field and a traffic field. There may also be residual (or spare) bandwidth that is available on the fiber 104 but unexploited by the ONUs, which is shown for the purpose of illustration as occupying a subframe SF 6 , although in reality the fields of this subframe do not carry useful information.
At the basic physical transport layer the address, control, signalling and traffic fields (or “channels”), are preferably time slots populated with bits and dedicated to transmitting certain classes of information from the HDT to the ONU. The address field in each subframe identifies the ONU for which the traffic is destined. The signalling field preferably carries instructions (such as ringing generator control) to a specific LIU in a known multiplexed format. The control field provides OAM status information and instructions to configure the mux 105 , thereby to allocate a certain bandwidth to each LIU according to the service-dependent bandwidth needs for that LIU. The control channel in the downstream subframes also provides control of the codec sampling and output rates in each LIU, as well as precise timing instructions for the transmittal of bursts of upstream data.
The traffic field is divided into a multitude of (in this case, twenty-nine) time slots T 1 -T 29 of “P” bits each. The BG can be defined as the bandwidth offered by the transmission of one time slot per frame, and is dependent on the number of bits per time slot (“P”) and on the above-identified frame size reduction factor (“M”). In mathematical terms,
BG= (#BITS/TIME SLOT)□(#SECONDS/FRAME)= P□ (125 μs□ M )=8× P×M kbps.
The number of time slots occupied by an LIU in a subframe is dependent on “M”, “P” and the required bandwidth by the LIU. It is useful to set P×M=64 (yielding a BG of 512 kbps) when the oversampled data is required to be sent at data rates that are multiples of 0.5 Mbps. Nonetheless, the bandwidth granularity is an arbitrary but fixed design parameter that can be designed to accommodate a different base multiple of bandwidth used in the system.
The traffic time slots are arranged into a known number (in this case, fifteen) of groups G 1 -G 15 , each group providing downstream data to a respective LIU. The number of time slots required per group is selectable and will depend on the bandwidth granularity and on the type of service provided.
These same time slots are used in the analogous construction of upstream subframes transmitted by the ONU 102 to the HDT 101 . The mux 105 forms a subframe that is subdivided into groups of time slots, whereby a group is associated with a specific LIU and is allotted a number of time slots that is dependent on the BG and on the required upstream bandwidth. Upon command from the HDT, an ONU transmits its fully constructed upstream subframe on a once-per-frame basis, although the subframes arriving from various ONUs are not contiguous, but instead arrive separated by guard bands.
The flow of downstream and upstream data between the core network and a subscriber, passing through the inventive access system, is now considered with reference to FIGS. 1C, 1 D and 4 B. It is particularly useful to contemplate two exemplary scenarios, denoted A and B. Scenario A deals with the situation in which the core network sends and receives multiplexed channels of 8-bit mu-law PCM voice data that are connected through the HDT and ONUs to analog subscriber loops that send and receive analog POTS signals. Scenario B treats the situation in which a Frame Relay (or similar packetized) service carried across an ATM core network is delivered to and from an end user as a Frame Relay service over a DS- 1 (1.544 Mbps) twisted pair link.
In downstream scenario A, switch matrix 131 routes the multiplexed channels of 8-bit mu-law encoded voice samples (arriving in a standard network format) to DSP 114 A after reformatting is done by the signalling processor 20 . DSP 114 A is dedicated to producing a stream 163 A of, say, 20-bit linearly encoded samples at 32 kHz from the 8-bit mu-law encoded data. In the prior art, this exact same function would be performed by a dedicated DSP within each destination LIU. In contrast, DSP 114 A in the present invention processes multiple channels destined for corresponding LIUs, and is thus effectively shared by a number of different LIUs. The data stream 163 A passes through interpolator 129 A so as to enter switch matrix 117 as a high-rate bit stream 164 A, typically on the order of 1 Mbps per channel. This data is in a generic data format, as it simply requires digital-to-analog conversion by the codec in the destination LIU.
Switch matrix 117 also accepts the other high rate data streams 164 B,C produced by the respective DSPs 114 B,C, and arranges the data into groups, subframes and frames according to destination LIU, ONU and PON in the manner described earlier. The optical downstream signal exiting the HDT, which may have a data rate on the order of several hundred Mbps, is converted to electronic format by the transceiver 6 and subsequently fed to the PON-OS 128 .
At the PON-OS 128 , the address field in each subframe is checked in order to determine whether the current ONU is the intended recipient of that subframe. Only the subframes intended for that particular ONU are output on link 135 to the mux 105 . For each LIU 103 , the mux 105 outputs, by a process of demultiplexing, the proper traffic time slots on the link 153 to the codec 111 , along with control information for the ringing generator 9 on link 133 . In addition, the PON-OS 128 provides control information to the ONU control processor 126 via link 123 ; alternatively, this information may be delivered from the mux 105 .
Within each LIU, the codec 111 then converts the high-rate bit stream on its network-side link 153 into an analog POTS waveform, and the AFE 8 adds appropriate ringing voltages and loop currents. As discussed earlier, the AFE is also responsible for removing the ringing voltage when an off-hook condition is detected, and may interface to a variety of loop termination media, such as copper twisted pair or coaxial cable.
Considering now the upstream path in scenario A, the AFE 8 will prepare the analog POTS signal for sampling by the oversampling codec 111 at around 1 MHz. The oversampled data 152 is fed to the mux 105 , where a suitable number of time slots in a subframe are allotted to this stream. Also, the mux 105 will partially fill the control and signalling fields with the status of the analog line received from the loop status detector 10 via path 134 . The address field will indicate the source ONU.
The mux 105 then assembles the time slots from each LIU, as well as all of the information in the remaining fields, forming a subframe, and sends it to the PON-OS 128 . The PON-OS waits for the go-ahead from the ONU control processor 126 before sending the subframe onto the fiber 4 via the transceiver 6 . The ONU control processor 126 receives this timing information from the HDT in the control field of the downstream subframes. Each ONU sharing the same fiber umbilical 4 a is cyclically instructed to send its burst of data, resulting in a “train” 400 of subframes SF 1 - 3 as shown in FIG. 3 B. Any consecutive pair of bursts is separated by a short time span 402 of variable length during which no transmission occurs, called a guard band. This is designed to account for the delay in instructing one ONU to transmit while ensuring that the previous ONU has ceased transmission.
The train 400 of data containing the oversampled POTS signal of upstream scenario A arrives at switch matrix 117 of the HDT 101 through transceiver 16 . The corresponding traffic time slots are extracted and routed via decimator 130 X to a DSP 114 X which converts the oversampled decimated data arriving from the subscriber to 8-bit mu-law data. DSP 114 X will likely be assigned the task of converting multiple upstream data channels from oversampled decimated format into mu-law format. The output 170 X of DSP 114 X subsequently passes through switch matrix 131 , where it is routed towards its possibly multiple destinations elsewhere in the network via transceivers 21 . The signalling processor 20 appropriately formats the outgoing signals prior to optoelectronic conversion by transceivers 21 .
In downstream scenario B, ATM cells arriving from the core network and carrying the Frame Relay service are routed by switch matrix 131 to a first DSP 114 B. DSP 114 B is dedicated to the process of reassembling segments of Frame Relay packets contained in the ATM cell stream into pure Frame Relay packets. This reassembly portion of a so-called segmentation and reassembly (SAR) process is achieved by removing the ATM envelope around the Frame Relay packet segments in the payload of each ATM cell and reassembling those segments into Frame Relay packets.
However, the output 166 of DSP 114 B is still not in a suitable format for delivery to the customer (who is expecting to receive line coded 1.544 Mbps DS- 1 data). Therefore, the output 163 B of DSP 114 B is rerouted to the input of another DSP processor 114 C by switch matrix 117 , hair pin connection 132 and switch matrix 131 . DSP 114 C is empowered with the insertion of Frame Relay packets into the payload of a 1.544 Mbps DS- 1 . DSP 114 C also formats the digital signal with the required line code, yielding data stream 163 C.
Data stream 163 C is subsequently passed through an interpolator 129 C to yield a very high rate oversampled bit stream 164 C, having a data rate on the order of 20 Mbps and requiring, for example, 40 time slots at a bandwidth granularity of 512 kbps per slot. The bit stream 164 C is multiplexed by switch matrix 117 and delivered to the appropriate codec 111 of the destination ONU in the manner described above. At the codec 111 , the oversampled line coded DS- 1 data is converted into an analog waveform, although the data per se is still in digital format, being encoded in the various voltage level durations and changes characteristic to the line code in use.
It is to be noted that bit stream 164 C in this downstream scenario B is in the same universal oversampled format as bit stream 164 A previously considered in downstream scenario A (although its rate is higher). In fact, the commonness of the data format communicated between the HDT and the ONUs (and vice versa) is an important property of the present invention. The rates, on the other hand, will depend on the service being offered, and the output or sampling rate of the codecs can be controlled via the downstream control channel, as previously discussed.
It is also noteworthy that interpolation is not applied at the output 163 B of DSP 114 B since this data requires further processing by DSP 114 C. This does not imply that an interpolator should be absent at the output of DSP 114 B, but rather that all interpolators 129 A,B,C be preferably equipped with “bypass mode” functionality (i.e., OUTPUT =INPUT), so that data which is hair pinned several times is interpolated only after having gone through the final DSP prior to delivery to the subscriber.
In upstream scenario B, the digital DS- 1 signal sent by the subscriber along the loop 7 undergoes frequency selective loss, accumulates noise and suffers from other impairments as it is propagated along the twisted pair drop. By the time the subscriber-emitted signal reaches the AFE 8 , regeneration is required to recover the original digital data from the distorted analog waveform. In the prior art, this regeneration is performed in the LIU proper. In contrast, the codec 111 in the inventive system simply oversamples the data at around 20 MHz as if it were a wideband analog input signal. In other words, the codec 111 “blindly” oversamples the signal and performs no data recovery, leaving the data in the common, high-bandwidth digital format.
The mux 105 inserts the oversampled bit stream into the time slots preassigned to that LIU, subsequently creating a subframe which is sent to the HDT via the PON-OS 128 and transceiver 6 using the upstream burst transmission procedure described above. Clearly, the inventive system trades bandwidth efficiency for simplicity of operation and economy of construction.
At the HDT, oversampled DS- 1 data arrives at a transceiver 16 , and is subsequently routed to a first DSP 114 Y which is programmed to recover the 1.544 Mbps bit stream from the oversampled version of the distorted line coded signal. This known regeneration process is achieved by a combination of frequency equalization, noise filtering and the application of a clocked decision threshold. The output 170 Y of DSP 114 Y is then routed to the input of a second DSP 114 Z via switch matrix 131 , hairpin connection 132 and switch matrix 117 .
The second DSP 114 Z removes the DS- 1 header and plainly outputs the payload in the form of Frame Relay packets which had been contained in the original DS- 1 stream. The output 170 Z of DSP 114 Z is once again “hair pinned” back to a third DSP (not shown) which segments the Frame Relay packets into ATM cells by applying the segmentation portion of the SAR process described above. Finally, the ATM data is ready to be sent to its destination through switch matrix 131 and a transceiver 21 . Analogous to interpolation in the downstream case, decimation performed in the HDT occurs only once, i.e., at the input to the first DSP in line for processing subscriber-generated data.
Typical oversampling and decimating rates for several common service types are illustrated in the following table:
Oversampled
Service
Bit Rate
Oversampled and Decimated Bit Rate
POTS
1-2 Mbps
32 kHz × 20 bits/word = 640 kbps
Foreign
1-2 Mbps
32 kHz × 20 bits/word = 640 kbps
Exchange
ISDN
2-10 Mbps
160 kHz × 10 bits/word = 1.6 Mbps
DS-1
20-40 Mbps
1.5 MHZ × 10 bits/word = 15 Mbps
Incidentally, it is also interesting to consider the requirements of the switch matrices 117 , 131 in view of the above rates. It is noted that the throughput of a prior art switch matrix 17 would determined by the aggregate fully formatted data capacity to and from all of the PONs connected to that switch matrix, whereas inventive switch matrix 117 is sized to carry the aggregate of all the oversampled data to and from the ONUs in addition to all of the data that is “hair pinned”, resulting in the requirement for a much larger data memory when using a standard 125 μs frame length. However, if the frame length is shortened to match the larger channel bandwidths of the oversampled signals, the memory requirement is reduced since less data arrives per frame. The value of M discussed above can thus be chosen to alleviate the requirements on switch matrix 117 by setting a convenient operating frame rate.
The digital switch matrix 131 has somewhat lesser requirements in that it handles data exiting the DSPs in a finalized format while also handling higher-bandwidth data “hair-pinned” back to the access side switch matrix 117 . However, no data need travel through switch matrix 131 in non-decimated form. Switch matrix 131 would thus be chosen as having a frame rate of standard length, i.e., 125 μs. Alternatively, several switches may be concatenated in the case where a high amount of “hair-pinning” is expected, one switch operating, for example, on a short frame with another one operating on a 125-μs frame.
It is important to note that relocation of digital signal processing tasks from the ONU to the HDT results in a cheaper, simpler, more efficient and more reliable ONU for deployment deep into the network. On the HDT side, considerable gains in DSP efficiency are also realized. For example, although individual processors are dedicated to a particular task, say conversion of mu-law PCM to linearly encoded samples, a single DSP can be used to perform the task at hand on a number of different data streams. These streams may be destined for completely different ports on the network, such as LIUs on different ONUs in different PONs. Whereas the number of processors required in the prior art was equal to the number of LIUs, the inventive system permits the use of a pool of DSP resources that can be shared across many LIUs. Since not all tasks require the same amount of processing, the HDT need concern itself with total DSP processing power, but not with a particular number of DSPs. Moreover, the DSPs themselves may offer varying degrees of processing ability, and need not be sized to accommodate the worst-case scenario of data conversion, as was formerly the case.
As an illustration of the DSP savings that can be achieved by the present invention, it is worthwhile to consider, for instance, a bank of 16 DSPs each capable of handling either 24 simultaneous mu-law-to-POTS conversions, 6 ISDN-to-POTS conversions or 1 DS- 1 -to-POTS conversion. If there exists a downstream service requirement for 192 POTS lines, 24 ISDN lines and 2 DS- 1 lines, then the following setup of DSPs would be able to accommodate the service mix:
8 DSPs×24 POTS lines/DSP→192 POTS LIUs serviced
4 DSPs×6 ISDN lines/DSP→24 ISDN LIUs serviced
2 DSP×1 DS- 1 lines/DSP→2 DS- 1 LIUs serviced
Clearly, a total of 218 LIUs can be accommodated by a mere 16 DSPs sized to handle DS- 1 -to-POTS conversion. This is minute compared to the 218 DSPs of at least the same power (i.e., not counting combinations of services) that would be required in a prior art approach based on service-independent line cards.
Notwithstanding the benefits of the inventive system given the artificial service mix assumed above, the following more detailed analysis of realistic loading conditions will reveal that in a typical service mix, the usage of a shared set of DSP blocks indeed allows each DSP to be more optimally loaded. For instance, if a DSP is capable of processing “m” lines of service type A, “n” lines of service type B and “p” lines of service type C, then, on a system with a total need to service “w” LIUs, the total DSP count for full service across the entire system is w/m+w/n+w/p. In other words, with DSPs in the HDT that are dedicated to a particular type of processing, one must stock up enough DSPs to cover any and all of the three worst cases. Clearly, DSP savings are achieved when
( w/m+w/n+w/p )< w,
or
(1/ m+ 1/ n+ 1/ p )<1.
Depending on the processing power of the DSPs in the HDT, this may require fewer resources than the prior art.
However, the advantages of centralizing the DSP resources become indisputable in the event that more than 3 lines of service on average (i.e., across all service types) can be processed in a DSP. Then m, n and p are all greater than 3 and the above inequality is satisfied, resulting in DSP savings due to “centralization” of DSP resources. Typical numbers for modern DSPs processing POTS, ISDN and DS- 1 are even more encouraging, and are on the order of 24 POTS/DSP, 6 ISDN/DSP, 2.5 DS- 1 /DSP, yielding (1/m+1/n+1/p)=0.6083.
The analysis may be extended one step further by applying known practical traffic mix requirement limits into the process of dimensioning the DSPs. For instance, if only a certain maximum percentage (e.g., 10%) of lines will ever need DS- 1 service and another maximum percentage of lines (e.g., 25%) will ever need ISDN service at one time (without knowing which lines are occupied by what service), then the above inequality becomes 1 / 24 * 100 % (POTS could be used 100% of the time) + 1 / 6 * 25 % (ISDN is used at most 25% of the time) + 1 / 2.5 * 10 % (DS-1 is used at most 10% of the time) 0.1233 < 1
for almost an order of magnitude savings (8.11:1) in the number of DSPs required.
On top of the added capacity, a further advantage of the present invention is that the DSPs are found in a centralized environment, which reduces the cost of provisioning and dimensioning the DSPs to meet future traffic demands. Moreover, the DSPs are flexible and their respective RAMs are reprogrammable by the control processor 119 , either through a control bus 183 as illustrated in FIG. 4B or through one of the switch matrices 117 , 131 , thereby providing the ability to track the evolving demands of the network.
The control processor 119 in the HDT can also play a vital role in reducing the bandwidth taken up by the various LIUs, particularly in the case of ISDN and DS- 1 services. For instance, an on-hook (unused) POTS line takes up very little bandwidth, as does an unused DS- 1 video conference line (i.e., the far end modem at the customer premises is in a quiescent mode), since the only requirement on that DS- 1 loop is to detect the start up of the DS- 1 Customer Premises Equipment. The control processor 119 can thus lower the sampling and output rates of the oversampling codecs and decimators on LIUs which are in an on-hook or quiescent condition to values much below that which the LIUs would require for an active delivery of POTS or DS- 1 services.
Hence, assuming a service mix of 80% POTS at 640 kbps, 10% ISDN at 1.6 Mbps, and 10% DS- 1 at 15 Mbps (all data rates are oversampled and decimated), and further assuming an average off-hook (in use) duty cycle of 25% along with 80% bandwidth reduction during on-hook (out of use) periods for both POTS and DS- 1 , then the average bandwidth per loop would be on the order of: [ ( 640 kbps * 25 % ) + ( 0.2 * 640 kbps * 75 % ) ] * 80 % + [ ( 1.6 Mbps * 100 % ) ] * 10 % + [ ( 15 Mbps * 25 % ) + ( 0.2 * 15 Mbps * 75 % ) ] * 10 % = 964.8 kbps per loop
This would allow up to 621 subscribers to be accessed with a single 600-Mbps PON, corresponding to the installation of up to sixteen 38-line ONUs or eight 77-line ONUs. A single fiber umbilical can thus serve a distribution area with over 600 customers, which is the norm for current North American telecommunications company serving areas.
The preceding example has assumed that decimated data are transmitted across the PON. This is achieved by an alternate embodiment of the present invention, in which the decimation and inverse functions are kept in the LIUs. Thus, considering the upstream path, a decimator would be placed between the codec 111 and the mux 105 instead of in the HDT. Optionally, decimators could be placed in both locations, whereby each upstream signal path would comprise one fully functional decimator and another operating in bypass mode. Clearly, analogous arrangements apply to the interpolators in the downstream path.
In another variant of the present invention, the functionality of the loop status processor 113 would be placed in each LIU 103 , 127 . Specifically, the loop status detector 10 may feed its signal 134 directly to the ONU control processor 126 or to an intermediate loop status processing block. The ONU control processor would perform the control functions of determining the condition of the line or decoding the dialled digits, relaying this information to the HDT via the upstream control channel. Similarly, the ringing generator 9 may be controlled from the ONU control processor 126 , thus further liberating the mux 105 , which is left with the task of simply routing the data to and from the LIUs.
It is also to be understood that many alternate embodiments of the present invention exist in which the processing chain in the HDT is configured differently than in FIG. 4 B. Such is the case in FIG. 4A, wherein a single high-capacity switch matrix 195 replaces the switch matrices 117 , 131 of FIG. 4 B. In this case, hair pinning does not require a link external to the switch matrix. Instead, data both from the ONUs and from the core network are continuously routed to the DSP bank and back through the switch matrix 195 until the required number of processing operations have been performed.
There may also be a 125-μs framed switch matrix 193 present at the core network side connected to the signalling processor which provides grooming of the frames leaving or entering the HDT at a 125 μs frame rate. In all other respects, the HDT is identical to that of FIG. 4 B.
Yet another example of an inventive HDT partitions the short-frame switch matrices of FIG. 4B into two, resulting in four STS switches 117 U, 117 D, 131 U, 131 D as shown in FIG. 4 C. In this case, two hair pin connections 132 U, 132 D are required, one for each direction travelled by the data. The signalling processor 20 now provides independent grooming of the frames in both the downstream and upstream paths. However, there is no fundamental difference in operation of the embodiment illustrated in FIG. 4C with respect to what has already been described with reference to FIG. 4 B.
Numerous other modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practised otherwise than as specifically described herein.
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An improved access system for use in a Fiber-In-The-Loop (FITL) communications network is disclosed. The access system comprises a host digital terminal (HDT) and a plurality of subtending optical network units (ONUs). The digital signal processing (DSP) functions traditionally executed by line interface units (LIUs) within the ONUs are migrated to the HDT, rendering the individual ONUs simpler, cheaper and more reliable. This is made possible by the provision in each ONU of an oversampling codec for sampling (and conversion) of upstream and downstream data at a very high bit rate. The large bandwidths of the data communicated between the ONUs and the HDT are easily handled by the fiber optic medium therebetween.
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RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 12/242,497, filed Sep. 30, 2008, the entire contents of which are hereby incorporated by reference in its entirety.
BACKGROUND
Due to its excellent biocompatibility, biostability and physical properties, polyurethane or polyurethane-containing polymers have been used to fabricate a large number of implantable devices, including pacemaker leads, artificial hearts, heart valves, stent coverings, artificial tendons, arteries and veins. Formulations for delivery of active agents using polyurethane implantable devices, however, require a liquid medium or carrier for the diffusion of the drug at a zero order rate.
SUMMARY
Described herein are methods and compositions based on the unexpected discovery that solid formulations comprising one or more active agents can be used at the core of a polyurethane implantable device such that the active agent is released in a controlled-release, zero-order manner from the implantable device. The active agents and polyurethane coating can be selected based on various physical parameters, and then the release rate of the active from the implantable device can be optimized to a clinically-relevant release rate based on clinical and/or in vitro trials.
One embodiment is directed to a method for delivering an active agent in a subject, comprising: implanting an implantable device into the subject, wherein the implantable device comprises an active agent surrounded by a polyurethane-based polymer, wherein the polyurethane-based polymer is selected according to one or more physical properties that allow for optimized release of the active agent from the implantable device after implantation into the subject. In a particular embodiment, the implantable device further comprising one or more pharmaceutically acceptable carriers. In a particular embodiment, the polyurethane-based polymer is selected based on its equilibrium water content or flex modulus. In a particular embodiment, the polyurethane-based polymer is selected based on the molecular weight of the active agent.
One embodiment is directed to a drug delivery device for the controlled release of at least one active agent over an extended period of time to produce local or systemic pharmacological effects, comprising: a) a polyurethane-based polymer formed to define a hollow space, wherein the polyurethane-based polymer comprises one or more functional groups selected from the group consisting of: hydrophilic pendant groups, hydrophobic pendant groups, and mixtures thereof, and wherein the functional groups determine the degree to which the polymer is hydrophobic or hydrophilic; and b) a solid drug formulation comprising at least one active agent and optionally one or more pharmaceutically acceptable carriers, wherein the solid drug formulation is in the hollow space of the cylindrically shaped reservoir, and wherein the polymer properties and the water solubility characteristics of the at least one active agent are chosen to provide a desired release rate of the active agent from the device after implantation. In a particular embodiment, the drug delivery device is conditioned and primed under conditions chosen to match the water solubility characteristics of the at least one active agent. In a particular embodiment, the conditioning and priming conditions include the use of an aqueous medium (e.g., a saline solution) when the at least one active agent is hydrophilic. In a particular embodiment, the conditioning and priming conditions include the use of a hydrophobic medium (e.g., an oil-based medium) when the at least one active agent is hydrophobic. In a particular embodiment, the at least one active agent is selected from the group consisting of: drugs that can act on the central nervous system, psychic energizers, tranquilizers, anti-convulsants, muscle relaxants, anti-parkinson agents, analgesics, anti-inflammatory agents, anesthetics, antispasmodics, muscle contractants, anti-microbials, anti-malarials, hormonal agents, sympathomimetics, cardiovascular agents, diuretics and antiparasitic agents. In a particular embodiment, the hydrophilic pendant groups are selected from the group consisting of: ionic, carboxyl, ether and hydroxyl groups. In a particular embodiment, the hydrophobic pendant groups are selected from the group consisting of: alkyl and siloxane groups. In a particular embodiment, the solid drug formulation comprises a pharmaceutically acceptable carrier (e.g., stearic acid). In a particular embodiment, the polyurethane-based polymer is thermoplastic polyurethane or thermoset polyurethane. In a particular embodiment, the thermoplastic polyurethane comprises macrodiols, diisocyanates, difunctional chain extenders or mixtures thereof. In a particular embodiment, the thermoset polyurethane comprises multifunctional polyols, isocyanates, chain extenders or mixtures thereof. In a particular embodiment, the thermoset polyurethane comprises a polymer chain that contains unsaturated bonds, and wherein appropriate crosslinkers and/or initiators are used to crosslink polymer subunits. In a particular embodiment, the appropriate conditioning and priming parameters can be selected to establish the desired delivery rates of the at least one active agent, wherein the priming parameters are time, temperature, conditioning medium and priming medium.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of an implant with two open ends.
FIG. 2 is a side view of pre-fabricated end plugs used to plug the implants.
FIG. 3 is a side view of an implant with one open end.
FIG. 4 is a graph of the elution rate of histrelin using an implant.
FIG. 5 is a graph of the elution rate of naltrexone from an implant.
FIG. 6 is a graph of the elution rate of naltrexone from polyurethane implants.
FIG. 7 is a graph of the elution rate of LHRH agonist (histrelin) from a polyurethane implant.
FIG. 8 is a graph of the elution rate of clonidine from a polyurethane implant.
FIGS. 9A and 9B are graphs showing elution from Carbothane® PC-3575A. FIG. 9A shows sections from the beginning, middle and end of a section of tubing. Elution was performed in a water bath or orbital shaker. FIG. 9B is a graph of the release rate of risperidone from Carbothane® PC-3575A polyurethane implants (Flex Modulus 620 psi) prepared from tubing sections representing the beginning, middle and end of a coil of tubing as part of an assessment of the uniformity of the material within a particular lot. Samples were evaluated weekly for one year for elution using a water bath. All implants were of equivalent geometry and drug load.
FIG. 10 is a graph of the release rate of risperidone from Carbothane® PC-3575A polyurethane implants (Flex Modulus 620 psi) as part of an assessment of the effect using saline versus aqueous hydroxypropyl betacellulose solution (15% in phosphate buffered saline) as the elution media. Samples were evaluated weekly for 11 weeks. All implants were of equivalent geometry and drug load.
FIGS. 11A and 11B are graphs comparing the release rates of risperidone from Carbothane® PC-3595A polyurethane implants (Flex modulus 4500 psi) to Tecophilic® HP-60D-20 polyurethane implants (EWC, 14.9%) as part of the evaluation of the release of the active from either hydrophilic and hydrophobic polyurethane materials. Samples were evaluated weekly for 22 weeks for the Carbothane® implant. Samples were evaluated weekly for 15 weeks for the Tecophilic® implant. All implants were of equivalent geometry and drug load. FIG. 11B is a graph of the release rate of risperidone from Tecophilic® HP-60D-20 polyurethane implants (EWC, 14.9%) alone, sampled weekly for 15 weeks.
FIG. 12 is a graph comparing the release rates of risperidone from Tecoflex® EG-80A polyurethane implants (Flex Modulus 1000 psi) and two grades of Tecophilic® polyurethane implants, HP-60D-35 and HP-60D-60 (EWC, 23.6% and 30.8%, respectively). All were sampled weekly for 10 weeks. All implants were of equivalent geometry and drug load.
FIG. 13 is a graph of the release rate of risperidone from Carbothane® PC-3575A polyurethane implants (Flex Modulus 620 psi) that served as in vitro controls for implants used in the beagle dog study described in Example 8. The in vitro elution study of these implants was initiated on the date of implantation of the subject implants as part of an assessment of in vivo-in vitro correlation.
FIG. 14 is a graph of the in vivo plasma concentration of risperidone in the beagle dog study described in Example 8. The lower plot represents the average plasma concentration achieved in dogs implanted with one Carbothane® PC-3575A polyurethane implant (Flex Modulus 620 psi). The upper plot represents the average plasma concentration achieved in dogs implanted with two Carbothane® PC-3575A polyurethane implants (Flex Modulus 620 psi).
DETAILED DESCRIPTION
To take the advantage of the excellent properties of polyurethane-based polymers, the present invention is directed to the use of polyurethane-based polymers as drug delivery devices for releasing drugs at controlled rates for an extended period of time to produce local or systemic pharmacological effects. The drug delivery device can comprise a cylindrically-shaped reservoir surrounded by polyurethane-based polymer that controls the delivery rate of the drug inside the reservoir. The reservoir contains a formulation, e.g., a solid formulation, comprising one or more active ingredients and, optionally, pharmaceutically acceptable carriers. The carriers are formulated to facilitate the diffusion of the active ingredients through the polymer and to ensure the stability of the drugs inside the reservoir.
A polyurethane is any polymer consisting of a chain of organic units joined by urethane links. Polyurethane polymers are formed by reacting a monomer containing at least two isocyanate functional groups with another monomer containing at least two alcohol groups in the presence of a catalyst. Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities.
Polyurethanes are in the class of compounds called “reaction polymers,” which include epoxies, unsaturated polyesters and phenolics. A urethane linkage is produced by reacting an isocyanate group, —N═C═O with a hydroxyl (alcohol) group, —OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R—(N═C═O) n≧2 and a polyol is a molecule with two or more hydroxyl functional groups, R′—(OH) n≧2 . The reaction product is a polymer containing the urethane linkage, —RNHCOOR′—. Isocyanates react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas.
Polyurethanes are produced commercially by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the “A-side” or just the “iso,” and represents the rigid backbone (or “hard segment”) of the system. The blend of polyols and other additives is commonly referred to as the “B-side” or as the “poly,” and represents the functional section (or “soft segment”) of the system. This mixture might also be called a “resin” or “resin blend.” Resin blend additives can include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments and fillers. In drug delivery applications, the “soft segments” represent the section of the polymer that imparts the characteristics that determine the diffusivity of an active pharmaceutical ingredient (API) through that polymer.
The elastomeric properties of these materials are derived from the phase separation of the hard and soft copolymer segments of the polymer, such that the urethane hard segment domains serve as cross-links between the amorphous polyether (or polyester) soft segment domains. This phase separation occurs because the mainly non-polar, low-melting soft segments are incompatible with the polar, high-melting hard segments. The soft segments, which are formed from high molecular weight polyols, are mobile and are normally present in coiled formation, while the hard segments, which are formed from the isocyanate and chain extenders, are stiff and immobile. Because the hard segments are covalently coupled to the soft segments, they inhibit plastic flow of the polymer chains, thus creating elastomeric resiliency. Upon mechanical deformation, a portion of the soft segments are stressed by uncoiling, and the hard segments become aligned in the stress direction. This reorientation of the hard segments and consequent powerful hydrogen-bonding contributes to high tensile strength, elongation, and tear resistance values.
The polymerization reaction is catalyzed by tertiary amines, such as, for example, dimethylcyclohexylamine, and organometallic compounds, such as, for example, dibutyltin dilaurate or bismuth octanoate. Furthermore, catalysts can be chosen based on whether they favor the urethane (gel) reaction, such as, for example, 1,4-diazabicyclo[2.2.2]octane (also called DABCO or TEDA), or the urea (blow) reaction, such as bis-(2-dimethylaminoethyl)ether, or specifically drive the isocyanate trimerization reaction, such as potassium octoate.
Isocyanates with two or more functional groups are required for the formation of polyurethane polymers. Volume wise, aromatic isocyanates account for the vast majority of global diisocyanate production. Aliphatic and cycloaliphatic isocyanates are also important building blocks for polyurethane materials, but in much smaller volumes. There are a number of reasons for this. First, the aromatically-linked isocyanate group is much more reactive than the aliphatic one. Second, aromatic isocyanates are more economical to use. Aliphatic isocyanates are used only if special properties are required for the final product. Light stable coatings and elastomers, for example, can only be obtained with aliphatic isocyanates. Aliphatic isocyanates also are favored in the production of polyurethane biomaterials due to their inherent stability and elastic properties.
Examples of aliphatic and cycloaliphatic isocyanates include, for example, 1,6-hexamethylene diisocyanate (HDI), 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane (isophorone diisocyanate, IPDI), and 4,4′-diisocyanato dicyclohexylmethane (H12MDI). They are used to produce light stable, non-yellowing polyurethane coatings and elastomers. H12MDI prepolymers are used to produce high performance coatings and elastomers with optical clarity and hydrolysis resistance. Tecoflex®, Tecophilic® and Carbothane® polyurethanes are all produced from H12MDI prepolymers.
Polyols are higher molecular weight materials manufactured from an initiator and monomeric building blocks, and, where incorporated into polyurethane systems, represent the “soft segments” of the polymer. They are most easily classified as polyether polyols, which are made by the reaction of epoxides (oxiranes) with an active hydrogen containing starter compounds, or polyester polyols, which are made by the polycondensation of multifunctional carboxylic acids and hydroxyl compounds.
Tecoflex® polyurethanes and Tecophilic® polyurethanes are cycloaliphatic polymers and are of the types produced from polyether-based polyols. For the Tecoflex® polyurethanes, the general structure of the polyol segment is represented as,
O—(CH 2 —CH 2 —CH 2 —CH 2 ) x —O—
whereby an increase in “x” represents a increase in flexibility (decreased “Flex Modulus”; “FM”), yielding FM ranging from about 1000-92,000 psi. From the standpoint of drug release from these materials, the release of a relatively hydrophobic API decreases as the FM increases.
For the Tecophilic® (hydrophilic) polyurethanes, the general structure of the polyol segment is represented as,
—[O—(CH 2 ) n ] x —O—
whereby increases in “n” and “x” represent variations in hydrophilicity, and yield equilibrium water contents (% EWC) ranging from about 5%-43%. From the standpoint of drug release from these materials, the release of a relatively hydrophilic API increases as the % EWC increases.
Specialty polyols include, for example, polycarbonate polyols, polycaprolactone polyols, polybutadiene polyols, and polysulfide polyols.
Carbothane® polyurethanes are cycloaliphatic polymers and are of the types produced from polycarbonate-based polyols. The general structure of the polyol segment is represented as,
O—[(CH 2 ) 6 —CO 3 ] n —(CH 2 )—O—
whereby an increase in “n” represents a increase in flexibility (decreased FM), yielding FM ranging from about 620-92,000 psi. From the standpoint of drug release from these materials, the release of a relatively hydrophobic API will decrease as the FM increases.
Chain extenders and cross linkers are low molecular weight hydroxyl- and amine-terminated compounds that play an important role in the polymer morphology of polyurethane fibers, elastomers, adhesives and certain integral skin and microcellular foams. Examples of chain extenders include, for example, ethylene glycol, 1,4-butanediol (1,4-BDO or BDO), 1,6-hexanediol, cyclohexane dimethanol and hydroquinone bis(2-hydroxyethyl)ether (HQEE). All of these glycols form polyurethanes that phase separate well, form well-defined hard segment domains, and are melt processable. They are all suitable for thermoplastic polyurethanes with the exception of ethylene glycol, since its derived bis-phenyl urethane undergoes unfavorable degradation at high hard segment levels. Tecophilic®, Tecoflex® and Carbothane® polyurethanes all incorporate the use of 1,4-butanediol as the chain extender.
The current invention provides a drug delivery device that can achieve the following objectives: a controlled-release rate (e.g., zero-order release rate) to maximize therapeutic effects and minimize unwanted side effects, an easy way to retrieve the device if it is necessary to end the treatment, an increase in bioavailability with less variation in absorption and no first pass metabolism.
The release rate of the drug is governed by the Fick's Law of Diffusion as applied to a cylindrically shaped reservoir device (cartridge). The following equation describes the relationship between different parameters:
ⅆ
M
ⅆ
t
=
2
π
hp
Δ
C
ln
(
r
o
/
r
i
)
where:
dM/dt
drug release rate;
h
length of filled portion of device;
ΔC
concentration gradient across the reservoir wall;
r o /r i
ratio of outside to inside radii of device; and
p
permeability coefficient of the polymer used.
The permeability coefficient is primarily regulated by the hydrophilicity or hydrophobicity of the polymer, the structure of the polymer, and the interaction of drug and the polymer. Once the polymer and the active ingredient are selected, p is a constant, h, ro, and r i are fixed and kept constant once the cylindrically-shaped device is produced. □C is maintained constant.
To keep the geometry of the device as precise as possible, the device, e.g., a cylindrically-shaped device, can be manufactured through precision extrusion or precision molding process for thermoplastic polyurethane polymers, and reaction injection molding or spin casting process for thermosetting polyurethane polymers.
The cartridge can be made with either one end closed or both ends open. The open end can be plugged with, for example, pre-manufactured end plug(s) to ensure a smooth end and a solid seal, or, in the case of thermoplastic polyurethanes, by using heat-sealing techniques known to those skilled in the art. The solid actives and carriers can be compressed into pellet form to maximize the loading of the actives.
To identify the location of the implant, radiopaque material can be incorporated into the delivery device by inserting it into the reservoir or by making it into end plug to be used to seal the cartridge.
Once the cartridges are sealed on both ends with the filled reservoir, they are optionally conditioned and primed for an appropriate period of time to ensure a constant delivery rate.
The conditioning of the drug delivery devices involves the loading of the actives (drug) into the polyurethane-based polymer that surrounds the reservoir. The priming is done to stop the loading of the drug into the polyurethane-based polymer and thus prevent loss of the active before the actual use of the implant. The conditions used for the conditioning and priming step depend on the active, the temperature and the medium in which they are carried out. The conditions for the conditioning and priming may be the same in some instances.
The conditioning and priming step in the process of the preparation of the drug delivery devices is done to obtain a determined rate of release of a specific drug. The conditioning and priming step of the implant containing a hydrophilic drug can be carried out in an aqueous medium, e.g., in a saline solution. The conditioning and priming step of a drug delivery device comprising a hydrophobic drug is usually carried out in a hydrophobic medium such as, for example, an oil-based medium. The conditioning and priming steps can be carried out by controlling three specific factors, namely the temperature, the medium and the period of time.
A person skilled in the art would understand that the conditioning and priming step of the drug delivery device is affected by the medium in which the device is placed. A hydrophilic drug can be conditioned and primed, for example, in an aqueous solution, e.g., in a saline solution. Histrelin and Naltrexone implants, for example, have been conditioned and primed in saline solution, more specifically, conditioned in saline solution of 0.9% sodium content and primed in saline solution of 1.8% sodium chloride content.
The temperature used to condition and prime the drug delivery device can vary across a wide range of temperatures, e.g., about 37° C.
The time period used for the conditioning and priming of the drug delivery devices can vary from about a single day to several weeks depending on the release rate desired for the specific implant or drug. The desired release rate is determined by one of skill in the art with respect to the particular active agent used in the pellet formulation.
A person skilled in the art will understand the steps of conditioning and priming the implants are to optimize the rate of release of the drug contained within the implant. As such, a shorter time period spent on the conditioning and the priming of a drug delivery device results in a lower rate of release of the drug compared to a similar drug delivery device that has undergone a longer conditioning and priming step.
The temperature in the conditioning and priming step will also affect the rate of release in that a lower temperature results in a lower rate of release of the drug contained in the drug delivery device when compared to a similar drug delivery device that has undergone a treatment at a higher temperature.
Similarly, in the case of aqueous solutions, e.g., saline solutions, the sodium chloride content of the solution determines what type of rate of release will be obtained for the drug delivery device. More specifically, a lower content of sodium chloride results in a higher rate of release of drug when compared to a drug delivery device that has undergone a conditioning and priming step where the sodium chloride content was higher.
The same conditions apply for hydrophobic drugs where the main difference in the conditioning and priming step is that the conditioning and priming medium is a hydrophobic medium, more specifically an oil-based medium.
The drug (actives) that can be delivered include drugs that can act on the central nervous system, psychic energizers, tranquilizers, anti-convulsants, muscle relaxants, anti-parkinson, analgesic, anti-inflammatory, anesthetic, antispasmodic, muscle contractants, anti-microbials, anti-malarials, hormonal agents, sympathomimetic, cardiovascular, diuretics, anti-parasitic and the like. Drugs also include drugs for use in urology, e.g., to treat or prevent a urological disorder or for contraception, such as, but not limited to, valrubicin, doxorubicin, bladder cancer cytotoxic agents, 5-amino salycilic acid (5-ASA), hydrocortisone, dexamethasone, anti-inflammatory agents, trospium chloride, tamsulosin, oxybutinin, and any hormone (such as, for example, ethinyl estradiol, levonorgestrel, estradiol, testosterone, and the like). Urological uses include, but are not limited to, for example, bladder cancer, interstitial cystitis, bladder inflammation, overactive bladder, benign prostatic hyperplasia (BPH), contraception, post-menopausal symptoms and hypogonatism. Implantable devices for use in bladder can range in size from, for example, about 2 mm to about 10 mm, from about 3 mm to about 6 mm, or about 2.7 mm in diameter and up to about 50 mm in length.
The current invention focuses on the application of polyurethane-based polymers, thermoplastics or thermosets, to the creation of implantable drug devices to deliver biologically active compounds at controlled rates for prolonged period of time. Polyurethane polymers can be made into, for example, cylindrical hollow tubes with one or two open ends through extrusion, (reaction) injection molding, compression molding, or spin-casting (see e.g., U.S. Pat. Nos. 5,266,325 and 5,292,515), depending on the type of polyurethane used.
Thermoplastic polyurethane can be processed through extrusion, injection molding or compression molding. Thermoset polyurethane can be processed through reaction injection molding, compression molding, or spin-casting. The dimensions of the cylindrical hollow tube should be as precise as possible.
Polyurethane-based polymers are synthesized from multi-functional polyols, isocyanates and chain extenders. The characteristics of each polyurethane can be attributed to its structure.
Thermoplastic polyurethanes are made of macrodiols, diisocyanates, and difunctional chain extenders (e.g., U.S. Pat. Nos. 4,523,005 and 5,254,662). Macrodiols make up the soft domains. Diisocyanates and chain extenders make up the hard domains. The hard domains serve as physical crosslinking sites for the polymers. Varying the ratio of these two domains can alter the physical characteristics of the polyurethanes, e.g., the flex modulus.
Thermoset polyurethanes can be made of multifunctional (greater than difunctional) polyols and/or isocyanates and/or chain extenders (e.g., U.S. Pat. Nos. 4,386,039 and 4,131,604). Thermoset polyurethanes can also be made by introducing unsaturated bonds in the polymer chains and appropriate crosslinkers and/or initiators to do the chemical crosslinking (e.g., U.S. Pat. No. 4,751,133). By controlling the amounts of crosslinking sites and how they are distributed, the release rates of the actives can be controlled.
Different functional groups can be introduced into the polyurethane polymer chains through the modification of the backbones of polyols depending on the properties desired. Where the device is used for the delivery of water soluble drugs, hydrophilic pendant groups such as ionic, carboxyl, ether, and hydroxy groups are incorporated into the polyols to increase the hydrophilicity of the polymer (e.g., U.S. Pat. Nos. 4,743,673 and 5,354,835). Where the device is used for the delivery of hydrophobic drugs, hydrophobic pendant groups such as alkyl, siloxane groups are incorporated into the polyols to increase the hydrophobicity of the polymer (e.g., U.S. Pat. No. 6,313,254). The release rates of the actives can also be controlled by the hydrophilicity/hydrophobicity of the polyurethane polymers.
For thermoplastic polyurethanes, precision extrusion and injection molding are the preferred choices to produce two open-end hollow tubes ( FIG. 1 ) with consistent physical dimensions. The reservoir can be loaded freely with appropriate formulations containing actives and carriers or filled with pre-fabricated pellets to maximize the loading of the actives. One open end needs to be sealed first before the loading of the formulation into the hollow tube. To seal the two open ends, two pre-fabricated end plugs ( FIG. 2 ) can be used. The sealing step can be accomplished through the application of heat or solvent or any other means to seal the ends, preferably permanently.
For thermoset polyurethanes, precision reaction injection molding or spin casting is the preferred choice depending on the curing mechanism. Reaction injection molding is used if the curing mechanism is carried out through heat and spin casting is used if the curing mechanism is carried out through light and/or heat. Hollow tubes with one open end ( FIG. 3 ), for example, can be made by spin casting. Hollow tubes with two open ends, for example, can be made by reaction injection molding. The reservoir can be loaded in the same way as the thermoplastic polyurethanes.
To seal an open end, an appropriate light-initiated and/or heat-initiated thermoset polyurethane formulation can be used to fill the open end, and this is cured with light and/or heat. A pre-fabricated end plug, for example, can also be used to seal the open end by applying an appropriate light-initiated and/or heat-initiated thermoset polyurethane formulation on to the interface between the pre-fabricated end plug and the open end, and curing it with the light and/or heat or any other means to seal the ends, preferably permanently.
The final process involves the conditioning and priming of the implants to achieve the delivery rates required for the actives. Depending upon the types of active ingredient, hydrophilic or hydrophobic, the appropriate conditioning and priming media is chosen. Water-based media are preferred for hydrophilic actives, and oil-based media are preferred for hydrophobic actives.
As a person skilled in the art would readily know many changes can be made to the preferred embodiments of the invention without departing from the scope thereof. It is intended that all matter contained herein be considered illustrative of the invention and not it a limiting sense.
EXEMPLIFICATION
Example 1
Tecophilic® polyurethane polymer tubes are supplied by Thermedics Polymer Products and manufactured through a precision extrusion process. Tecophilic® polyurethane is a family of aliphatic polyether-based thermoplastic polyurethane that can be formulated to different equilibrium water contents (EWC) of up to 150% of the weight of dry resin. Extrusion grade formulations are designed to provide maximum physical properties of thermoformed tubing or other components. An exemplary tube and end cap structures are depicted in FIGS. 1-3 .
The physical data for the polymers is provided below as made available by Thermedics Polymer Product (tests conducted as outlined by American Society for Testing and Materials (ASTM), Table 1).
TABLE 1
Tecophilic ® Typical Physical Test Data
ASTM
HP-60D-20
HP-60D-35
HP-60D-60
HP-93A-100
Durometer
D2240
43D
42D
41D
83A
(Shore Hardness)
Spec Gravity
D792
1.12
1.12
1.15
1.13
Flex Modulus (psi)
D790
4,300
4,000
4,000
2,900
Ultimate Tensile Dry (psi)
D412
8,900
7,800
8,300
2,200
Ultimate Tensile Wet (psi)
D412
5,100
4,900
3,100
1,400
Elongation Dry (%)
D412
430
450
500
1,040
Elongation Wet (%)
D412
390
390
300
620
HP-60D-20 is extruded to tubes with thickness of 0.30 mm with inside diameter of 1.75 mm. The tubes are then cut into 25 mm in length. One side of the tube is sealed with heat using a heat sealer. The sealing time is less than one minute. Four pellets of histrelin acetate are loaded into the tube. Each pellet weighs approximately 13.5 mg for a total of 54 mg. Each pellet is comprised of a mixture of 98% histrelin and 2% stearic acid. The second end open of the tube is sealed with heat in the same way as for the first end. The loaded implant is then conditioned and primed. The conditioning takes place at room temperature in a 0.9% saline solution for one day. Upon completion of the conditioning, the implant undergoes priming. The priming takes place at room temperatures in a 1.8% saline solution for one day. Each implant is tested in vitro in a medium selected to mimic the pH found in the human body. The temperature of the selected medium was kept at approximately 37° C. during the testing. The release rates are shown on FIG. 4 and Table 2.
TABLE 2
Histrelin Elution Rates
WEEKS OF
HP-60D-20
ELUTION
(μg/day)
1
451.733
2
582.666
3
395.9
4
310.29
5
264.92
6
247.17
7
215.93
8
201.78
9
183.22
10
174.99
11
167.72
12
158.37
13
153.95
14
146.46
15
139.83
16
129.6
17
124.46
18
118.12
19
120.35
Example 2
HP-60D-35 is extruded to tubes with thickness of 0.30 mm with inside diameter of 1.75 mm. The tubes are then cut into 32 mm in length. One side of the tube is sealed with heat using a heat sealer. The sealing time is less than one minute. Six pellets of naltrexone are loaded into the tubes and both open sides of the tubes are sealed with heat. Each pellet weighs approximately 15.0 mg for a total of 91 mg. The second end open of the tube is sealed with heat in the same way as for the first end. The loaded implant is then conditioned and primed. The conditioning takes place at room temperature in a 0.9% saline solution for one week. Upon completion of the conditioning, the implant undergoes priming. The priming takes place at room temperatures in a 1.8% saline solution for one week. Each implant is tested in vitro in a medium selected to mimic the pH found in the human body. The temperature of the selected medium was kept at approximately 37° C. during the testing. The release rates are shown on FIG. 5 and Table 3.
TABLE 3
Naltrexone Elution Rates
WEEKS OF
HP-60D-35-1
HP-60D-35-2
HP-60D-35-3
RELEASE
(μg/day)
(μg/day)
(μg/day)
0
1
1529.26
767.38
1400.95
2
1511.77
1280.03
1498.86
3
1456.01
1635.97
1449.49
4
1378.27
1607.13
1500.42
5
1393.05
1614.52
1558.37
6
1321.71
1550.39
1436.03
7
1273.07
1424.24
1300.73
8
1172.82
1246.48
1221.57
Example 3
In FIG. 6 there is a comparison of the release rates of naltrexone in vitro using two grades of polymer at two different water contents. Three runs were carried out and analyzed where the polymer of the implant had a water content of 24% and three runs were carried out where the polymer of the implant had a water content of 30%. The release rates were plotted against time. The polymer used for the runs at 24% water content was Tecophilic® HP-60-D35 from Thermedics. The polymer used for the runs at 30% water content was Tecophilic® HP-60-D60 from Thermedics. The data obtained in this example demonstrate the good reproducibility of the implants as prepared according to the present invention.
Example 4
FIG. 7 shows a plot of the release rate of histrelin (LHRH agonist) versus time. The polymer in this example had a water content of 15%. The polymer used was Tecophilic® HP-60-D20 from Thermedics. The data points were taken weekly.
Example 5
FIG. 8 shows a plot of the release rate of clonidine versus time. The polymer in this example has a water content of 15%. The polymer used was Tecophilic® HP-60-D20 from Thermedics. The data points were taken weekly.
Example 6
Tables 4A-C show release rates of active agents from three different classes of polyurethane compounds (Tecophilic®, Tecoflex® and Carbothane®). The release rates have been normalized to surface area of the implant, thereby adjusting for slight differences in the size of the various implantable devices. The active agents were selected to cover a range of solubilities (as indicated by the varying Log P values; for the purposes of the data provided, a Log P value of greater than about 2.0 is considered to be not readily soluble in aqueous solution) and molecular weights. The polyurethanes were selected to have varying affinities for water soluble active agents and varying flexibility (as indicated by the variation in flex modulus).
For applications of the polyurethanes useful for the devices and methods described herein, the polyurethane exhibits physical properties suitable for the specific active agent to be delivered. Polyurethanes are available or can be prepared, for example, with a range of EWCs or flex moduli (Table 4). Tables 4A-C show normalized release rates for various active ingredients from polyurethane compounds. Tables 4D-F show the non-normalized release rates for the same active ingredients, together with implant composition.
TABLE 4A
Polyurethane Type Tecophilic
Polyurethane Grade
HP-60D-60
HP-60D-35
HP-60D-20
HP-60D-10
HP-60D-05
% EWC/Flex Modulus
Active
Relative Water Solubility
31% EWC
24% EWC
15% EWC
8.7% EWC
5.5% EWC
Octreotide
Very soluble,
—
2022
758
11
0
Acetate
Log P = 0.43
μg/day/cm 2
μg/day/cm 2
μg/day/cm 2
10% HPC, 2% SA,
(M.W. 1019)
2% SA
5% HPC, 2% SA;
10% HPC, 2% SA,
50 mg API
50 mg API
50 mg API
50 mg API
Histrelin
Very soluble
309
248
93
—
—
Acetate
Log P = (n/a)
μg/day/cm 2
μg/day/cm 2
μg/day/cm 2
(M.W. 1323)
2% SA
2% SA
2% SA
50 mg API
50 mg API
50 mg API
Selegiline
Freely soluble
—
—
294
—
—
HCL
Log P = (n/a)
μg/day/cm 2
(M.W. 224)
2% SA
66.8 mg API
Dexamethasone
Log P = 1.93
—
—
85
—
—
(M.W. 392)
μg/day/cm 2
10% CC, 2% SA,
47.5 mg API
Naltrexone
Log P = 2.07
883
704
263
127
12.7
Base
μg/day/cm 2
μg/day/cm 2
μg/day/cm 2
μg/day/cm 2
μg/day/cm 2
(M.W. 285)
10% CC, 2% SA +
2% SA
10% CC, 2% SA,
10% CC, 2% SA +
10% CC, 2% SA,
PEG 400, 79.2 mg API
91.3 mg API
193.6 mg API
PEG 400, 197.1 mg API
144.6 mg API
Metolazone
Log P = 2.50
—
—
50
—
—
(M.W. 366)
μg/day/cm 2
10% CC, 2% SA,
82.7 mg API
Clonidine
Log P = 2.56
—
—
1011
—
—
Base
μg/day/cm 2
(M.W. 230)
2% SA
~50 mg API
Risperidone
Log P = 3.28
—
—
149
—
—
(M.W. 410)
μg/day/cm 2
10% CC, 2% SA,
28.5 mg API
TABLE 4B
Polyurethane Type Tecoflex
Polyurethane Grade
EG-85A
EG 100A
EG-65D
Relative Water
% EWC/Flex Modulus
Active
Solubility
F.M.: 2,300
F.M.: 10,000
F.M.: 37,000
Octreotide
Very soluble,
16 μg/day/cm 2
—
—
Acetate
Log P = 0.43
10% HPC, 2% SA,
(M.W. 1019)
50 mg API
Histrelin
Very soluble
—
0.3 μg/day/cm 2
—
Acetate
Log P = (n/a)
2% SA
(M.W. 1323)
50 mg API
Selegiline HCL
Freely soluble
1518 μg/day/cm 2
7.2 μg/day/cm 2
4.1 μg/day/cm 2
(M.W. 224)
Log P = (n/a)
2% SA
2% SA
2% SA
67.2 mg API
63.5 mg API
63.1 mg API
Dexamethasone
Log P = 1.93
40 μg/day/cm 2
2.6 μg/day/cm 2
0.5 μg/day/cm 2
(M.W. 392)
10% CC, 2% SA,
10% CC, 2% SA,
10% CC, 2% SA,
47.3 mg API
54.5 mg API
53.1 mg API
Naltrexone
Log P = 2.07
—
23 μg/day/cm 2
—
Base
10% CC, 2% SA,
(M.W. 285)
75.5 mg API
Metolazone
Log P = 2.50
32 μg/day/cm 2
2.3 μg/day/cm 2
—
(M.W. 366)
10% CC, 2% SA,
10% CC, 2% SA,
82.7 mg API
82.0 mg API
Clonidine
Log P = 2.56
1053 μg/day/cm 2
88 μg/day/cm 2
25 μg/day/cm 2
Base
20% CC, 2% SA,
20% CC, 2% SA,
20% CC, 2% SA,
(M.W. 230)
80.3 mg API
65.7 mg API
66.3 mg API
Risperidone
Log P = 3.28
146 μg/day/cm 2
7.6 μg/day/cm 2
1.9 μg/day/cm 2
(M.W. 410)
10% CC, 2% SA,
10% CC, 2% SA,
10% CC, 2% SA,
27.9 mg API
29.8 mg API
29.7 mg API
TABLE 4C
Polyurethane Type Carbothane
Polyurethane Grade
PC-3575A
PC-3595A
Relative Water
% EWC/Flex Modulus
Active
Solubility
F.M.: 620
F.M.: 4,500
Octreotide
Very soluble,
—
—
Acetate
Log P = 0.43
(M.W. 1019)
Histrelin Acetate
Very soluble
—
0.2 μg/day/cm 2
(M.W. 1323)
Log P = (n/a)
2% SA
50 mg API
Selegiline HCL
Freely soluble
36 μg/day/cm 2
15 μg/day/cm 2
(M.W. 224)
Log P = (n/a)
2% SA
2% SA
65.3 mg API
66.8 mg API
Dexamethasone
Log P = 1.93
6.2 μg/day/cm 2
2.3 μg/day/cm 2
(M.W. 392)
10% CC, 2% SA,
10% CC, 2% SA,
47.1 mg API
53.2 mg API
Naltrexone Base
Log P = 2.07
—
5.5 μg/day/cm 2
(M.W. 285)
10% CC, 2% SA,
189.2 mg API
Metolazone
Log P = 2.50
8.4 μg/day/cm 2
2.6 μg/day/cm 2
(M.W. 366)
10% CC, 2% SA,
10% CC, 2% SA,
82.7 mg API
81.6 mg API
Clonidine Base
Log P = 2.56
202 μg/day/cm 2
136 μg/day/cm 2
(M.W. 230)
20% CC, 2% SA,
20% CC, 2% SA,
66.5 mg API
64.6 mg API
Risperidone
Log P = 3.28
40 μg/day/cm 2
11 μg/day/cm 2
(M.W. 410)
10% CC, 2% SA,
10% CC, 2% SA,
27.8 mg API
29.7 mg API
TABLE 4D
Polyurethane Tecophilic
Grade
HP-60D-60
HP-60D-35
HP-60D-20
HP-60D-10
HP-60D-05
% EWC
Active
Relative Water Solubility
31% EWC
24% EWC
15% EWC
8.7% EWC
5.5% EWC
Octreotide
Very soluble,
—
4000 μg/day
1500 μg/day
25 μg/day
0
Acetate
Log P = 0.43
ID: 1.80 mm
ID: 1.80 mm
ID: 1.83 mm
(M.W. 1019)
Wall: 0.30 mm
Wall: 0.30 mm
Wall: 0.30 mm
L: 30 mm
L: 30 mm
L: 34 mm
1.978 cm 2
1.978 cm 2
2.274 cm 2
Histrelin
Very soluble
500 μg/day
400 μg/day
150 μg/day
—
—
Acetate
Log P = (n/a)
ID: 1.80 mm
ID: 1.80 mm
ID: 1.80 mm
(M.W. 1323)
Wall: 0.30 mm
Wall: 0.30 mm
Wall: 0.30 mm
L: 24.5 mm
L: 24.5 mm
L; 24.5 mm
1.616 cm 2
1.616 cm 2
1.616 cm 2
Selegiline
Freely soluble
—
—
600 μg/day
—
—
HCL
Log P = (n/a)
ID: 1.80 mm
(M.W. 224)
Wall: 0.3 mm
L: 30.9 mm
2.038 cm 2
Dexamethasone
Log P = 1.93
—
—
170 μg/day
—
—
(M.W. 392)
ID: 1.80 mm
Wall: 0.30 mm
L: 30.24 mm
1.994 cm 2
Naltrexone
Log P = 2.07
2200 μg/day
1500 μg/day
1000 μg/day
500 μg/day
50 μg/day
Base
ID: 1.80 mm
ID: 1.80 mm
ID: 2.87 mm
ID: 3.05 mm
ID: 3.05 mm
(M.W. 285)
Wall: 0.30 mm
Wall: 0.30 mm
Wall: 0.38 mm
Wall: 0.30 mm
Wall: 0.30 mm
L: 37.8 mm
L: 32.3 mm
L: 37.2 mm
L: 37.3 mm
L: 37.4 mm
2.492 cm 2
2.130 cm 2
3.796 cm 2
3.924 cm 2
3.934 cm 2
Metolazone
Log P = 2.50
124 μg/day
(M.W. 366)
ID: 1.80 mm
Wall: 0.30 mm
L: 37.4 mm
2.466 cm 2
Clonidine
Log P = 2.56
—
—
2000 μg/day
—
—
Base
ID: 1.80 mm
(M.W. 230)
Wall: 0.30 mm
L: 30.0 mm
1.978 cm 2
Risperidone
Log P = 3.28
—
—
150 μg/day
—
—
(M.W. 410)
ID: 1.80 mm
Wall: 0.30 mm
L: 15.24 mm
1.005 cm 2
TABLE 4E
Polyurethane Type Tecoflex
Polyurethane Grade
EG-85A
EG 100A
EG-65D
Relative Water
Flex Modulus
Active
Solubility
F.M.: 2,300
F.M.: 10,000
F.M.: 37,000
Octreotide Acetate
Very soluble,
30 μg/day
—
—
(M.W. 1019)
Log P = 0.43
ID: 1.85 mm
Wall: 0.20 mm
L: 30 mm
1.931 cm 2
Histrelin Acetate
Very soluble
—
0.5 μg/day
—
(M.W. 1323)
Log P = (n/a)
ID: 1.85 mm
Wall: 0.20 mm
L; 25.56 mm
1.645 cm 2
Selegiline HCL
Freely soluble
3000 μg/day
14 μg/day
8 μg/day
(M.W. 224)
Log P = (n/a)
ID: 1.85 mm
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.2 mm
Wall: 0.20 mm
L: 30.7 mm
L: 30.2 mm
L: 30.4 mm
1.976 cm 2
1.944 cm 2
1.957 cm 2
Dexamethasone
Log P = 1.93
80 μg/day
5 μg/day
1.0 μg/day
(M.W. 392)
ID: 1.85 mm
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 30.9 mm
L: 30.0 mm
L: 30.7 mm
1.989 cm 2
1.931 cm 2
1.976 cm 2
Naltrexone Base
Log P = 2.07
—
55 μg/day
—
(M.W. 285)
ID: 1.85 mm
Wall: 0.20 mm
L: 37.49 mm
2.413 cm 2
Metolazone
Log P = 2.50
77 μg/day
5.5 μg/day
(M.W. 366)
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 37.7 mm
L: 37.15 mm
2.427 cm 2
2.391 cm 2
Clonidine Base
Log P = 2.56
2000 μg/day
175 μg/day
50 μg/day
(M.W. 230)
ID: 1.85 mm
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 29.5 mm
L: 30.8 mm
L: 30.8 mm
1.899 cm 2
1.983 cm 2
1.983 cm 2
Risperidone
Log P = 3.28
150 μg/day
8 μg/day
2 μg/day
(M.W. 410)
ID: 1.85 mm
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 16.0 mm
L: 16.4 mm
L: 16.2 mm
1.030 cm 2
1.056 cm 2
1.043 cm 2
TABLE 4F
Polyurethane Type Carbothane
Polyurethane Grade
PC-3575A
PC-3595A
Relative Water
Flex Modulus
Active
Solubility
F.M.: 620
F.M.: 4,500
Octreotide
Very soluble,
—
—
Acetate
Log P = 0.43
(M.W. 1019)
Histrelin Acetate
Very soluble
—
0.4 μg/day
(M.W. 1323)
Log P = (n/a)
ID: 1.85 mm
Wall: 0.20 mm
L; 25.25 mm
1.625 cm 2
Selegiline HCL
Freely soluble
70 μg/day
30 μg/day
(M.W. 224)
Log P = (n/a)
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 29.9 mm
L: 30.6 mm
1.925 cm 2
1.970 cm 2
Dexamethasone
Log P = 1.93
12 μg/day
4.5 μg/day
(M.W. 392)
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 30.0 mm
L: 30.7 mm
1.931 cm 2
1.976 cm 2
Naltrexone Base
Log P = 2.07
—
25 μg/day
(M.W. 285)
ID: 3.63 mm
Wall: 0.18 mm
L: 38.19 mm
4.569 cm 2
Metolazone
Log P = 2.50
20 μg/day
6.1 μg/day
(M.W. 366)
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 37.0 mm
L: 37.02 mm
2.382 cm 2
2.383 cm 2
Clonidine Base
Log P = 2.56
400 μg/day
270 μg/day
(M.W. 230)
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 30.8 mm
L: 30.8 mm
1.983 cm 2
1.983 cm 2
Risperidone
Log P = 3.28
40 μg/day
11 μg/day
(M.W. 410)
ID: 1.85 mm
ID: 1.85 mm
Wall: 0.20 mm
Wall: 0.20 mm
L: 15.6 mm
L: 16.2 mm
1.004 cm 2
1.043 cm 2
The solubility of an active agent in an aqueous environment can be measured and predicted based on its partition coefficient (defined as the ratio of concentration of compound in aqueous phase to the concentration in an immiscible solvent). The partition coefficient (P) is a measure of how well a substance partitions between a lipid (oil) and water. The measure of solubility based on P is often given as Log P. In general, solubility is determined by Log P and melting point (which is affected by the size and structure of the compounds). Typically, the lower the Log P value, the more soluble the compound is in water. It is possible, however, to have compounds with high Log P values that are still soluble on account of, for example, their low melting point. It is similarly possible to have a low Log P compound with a high melting point, which is very insoluble.
The flex modulus for a given polyurethane is the ratio of stress to strain. It is a measure of the “stiffness” of a compound. This stiffness is typically expressed in Pascals (Pa) or as pounds per square inch (psi).
The elution rate of an active agent from a polyurethane compound can vary on a variety of factors including, for example, the relative hydrophobicity/hydrophilicity of the polyurethane (as indicated, for example, by log P), the relative “stiffness” of the polyurethane (as indicated, for example, by the flex modulus), and/or the molecular weight of the active agent to be released.
Example 7
Elution of Risperidone from Polyurethane Implantable Devices
FIGS. 9-14 are graphs showing elution profiles of risperidone from various implantable devices over varying periods of time.
Release rates were obtained for risperidone from Carbothane® PC-3575A polyurethane implants (F.M. 620 psi) prepared from tubing sections representing the beginning, middle and end of a coil of tubing as part of an assessment of the uniformity of the material within a particular lot ( FIG. 9 ). Samples were evaluated weekly for one year. All implants were of equivalent geometry and drug load.
Release rates were obtained for risperidone from Carbothane® PC-3575A polyurethane implants (F.M. 620 psi) as part of an assessment of the effect using saline versus aqueous hydroxypropyl betacellulose solution (15% in phosphate buffered saline) as the elution media ( FIG. 10 ). Samples were evaluated weekly for 11 weeks. All implants were of equivalent geometry and drug load.
Release rates were compared for risperidone from Carbothane® PC-3595A polyurethane implants (F.M. 4500 psi) and Tecophilic® HP-60D-20 polyurethane implants (EWC 14.9%) as part of the evaluation of the release of the active from either hydrophilic and hydrophobic polyurethane materials ( FIGS. 11A and 11B ). Samples were evaluated weekly for 22 weeks for the Carbothane® implant. Samples were evaluated weekly for 15 weeks for the Tecophilic® implant. All implants were of equivalent geometry and drug load.
Release rates were compared for risperidone from Tecoflex® EG-80A polyurethane implants (F.M. 1000 psi) and two grades of Tecophilic® polyurethane implants, HP-60D-35 and HP-60D-60 (EWC, 23.6% and 30.8%, respectively) ( FIG. 12 ). All were sampled weekly for 10 weeks. All implants were of equivalent geometry and drug load.
Release rates were obtained for risperidone from Carbothane® PC-3575A polyurethane implants (F.M. 620 psi) that served as in vitro controls for implants used in the beagle dog study described in Example 8. The in vitro elution study of these implants was initiated on the date of implantation of the subject implants as part of an assessment of in vivo-in vitro correlation.
Example 8
Evaluation of Polyurethane Subcutaneous Implant Devices Containing Risperidone in Beagle Dogs
The purposes of this study are to determine the blood levels of risperidone from one or two implants and the duration of time the implants will release drug. Polyurethane-based implantable devices comprising a pellet comprising risperidone were implanted into beagles to determine release rates of risperidone in vivo. The results of the sample analysis are summarized in Table 5 and FIG. 14 . Risperidone is still present at a high level in the dog plasma at the end of the third month. The study was conducted in accordance with WCFP's standard operating procedures (SOPs), the protocol, and any protocol amendments. All procedure were conducted in accordance with the Guide for the Care and Use of Laboratory Animals (National Research Center, National Academy Press, Washington, D.C., 1996), and approved by the Institutional Animal Care and Use Committee in WCFP.
The implants initially contained about 80 mg of risperidone and are designed to deliver approximately 130 mcg/day for 3 months. The test article was stored at between 2-8° C. before use.
The animals were as follows:
Species: Canine
Strain: Beagle dog
Source: Guangzhou Pharm. Industril Research Institute,
Certification No: SCXK(YUE) 2003-0007
Age at Initiation of Treatment: 6˜9 months
Weight: 8˜10 kg
Number and Sex: 6 males
Prior to study initiation, animals were assigned a pretreatment identification number. All animals were weighed before administration once weekly, and received cage-side observations daily by qualified veterinarian during acclimation period. All animals were given a clinical examination prior to selection for study. Animals with any evidence of disease or physical abnormalities were not selected for study. The blood sampling was taken as Baseline at the 3rd and 2nd day before implant. Animals were then randomized into to 2 groups, with the dosing schedule provided as follows:
No. of
Animals
Dose rate
Group
Dose Route
Male
(mcg/day)
Total Dose (mg)
1
Subcutaneous
3
130
23 (single implant)
implant
2
Subcutaneous
3
260
46 (double implants)
implant
Each animal was anesthetized by general anesthesia via pentobarbital sodium at the dose of 30 mg/kg for device implantation. The drug was released at a steady rate for several months. Half the animals received one implant (group 1) and the others received two implants (group 2). A 5 cm2 area of the shoulder was shaved and 2 mL of marcaine infused under the skin to numb the area. A small incision was made on the shoulder and the device was slid under the skin. The small incision was closed and the animal was allowed to recover and return to his run. Over the next five to seven days, the implantation site was be monitored for signs of infection or reaction. The skin staples were removed when the skin has healed sufficiently. At the end of three months, the devices were removed, just as they would clinically.
Animals were fasted at least four hours prior to blood sampling. Since blood sampling was done in the morning, food was withheld overnight. Blood samples were drawn using a 20G needle and collected directly into the 5 mL tubes containing sodium heparin and maintained chilled until centrifugation. Samples were then centrifuged at 5000 RPM for 5 minutes at 4° C. The separated plasma was then be transferred into two 3 mL cryo tubes. The samples were labeled with the actual date the sample was taken, the corresponding study day, the dog identification and the duplicate sample designator (either A or B). Samples were kept at −20° C. until ready for analysis.
On two consecutive days, prior to implantation of the delivery device, baseline blood samples were taken. In addition, daily blood samples were taken during the first week and weekly blood samples were taken for the three months following implantation. Two 5 mL blood samples were drawn at each time from each dog. Blood samples were drawn from the cephalic veins primarily; with the saphenous or jugular used as a backup. For both the single and double implant groups, blood samples were drawn at appropriate times as outlined in Table 5 below. Analysis required at least 2 mL of plasma, which required no less than 10 mL of blood drawn for each sample. Analysis of plasma concentrations of risperidone was performed using an LC/MS assay developed for this compound. A single assay was be run for each sample. Samples were collected, held at the appropriate condition and analyzed in batches.
TABLE 5
Concentration of Risperidone in Dog Plasma
Group 1(single implant)
Group 2(double implants)
Group 1
Group 2
Date
Week
Day
1M01
1M02
1M03
2M01
2M02
2M03
Mean
S.D.
Mean
S.D.
−3
—
—
—
—
—
—
−2
—
—
—
—
—
—
1.29
1
1
BLQ
BLQ
0.26
BLQ
0.54
BLQ
0.26
/
0.54
/
1.30
1
2
0.77
BLQ
0.24
0.53
1.86
0.46
0.51
0.37
0.95
0.79
1.31
1
3
1.16
0.78
0.37
1.15
2.70
0.92
0.77
0.40
1.59
0.97
2.01
1
4
1.26
0.79
0.66
1.21
3.85
0.94
0.90
0.32
2.00
1.61
2.02
1
5
1.15
0.66
1.03
1.02
3.13
0.77
0.95
0.26
1.64
1.30
2.03
1
6
1.14
0.58
0.52
0.97
2.96
0.79
0.75
0.34
1.57
1.20
2.04
1
7
1.17
0.72
0.44
0.89
3.27
0.73
0.78
0.37
1.63
1.42
2.11
2
14
1.26
1.03
0.38
1.15
2.81
1.01
0.89
0.46
1.66
1.00
2.18
3
21
1.09
0.70
0.62
1.38
3.09
0.91
0.80
0.25
1.79
1.15
2.25
4
28
1.34
0.84
1.02
1.71
3.55
1.10
1.07
0.25
2.12
1.28
3.03
5
35
2.07
2.23
1.65
1.97
4.54
1.12
1.98
0.30
2.54
1.78
3.10
6
42
1.53
1.13
1.87
1.86
3.34
1.40
1.51
0.37
2.20
1.01
3.17
7
49
1.33
1.09
1.16
1.67
2.23
1.29
1.19
0.12
1.73
0.47
3.24
8
56
1.56
1.29
1.30
1.28
2.09
1.54
1.38
0.15
1.64
0.41
3.31
9
63
1.06
0.83
1.39
1.13
2.27
0.97
1.09
0.28
1.46
0.71
4.07
10
70
1.39
1.00
1.36
1.42
3.51
1.48
1.25
0.22
2.14
1.19
4.14
11
77
1.23
1.15
1.41
1.61
3.47
1.07
1.26
0.13
2.05
1.26
4.21
12
84
1.29
1.10
1.21
1.23
3.47
1.23
1.20
0.10
1.98
1.29
4.28
13
91
1.38
0.88
1.10
1.09
3.22
1.38
1.12
0.25
1.90
1.16
5.05
14
98
1.94
1.01
1.32
1.28
3.76
1.19
1.42
0.47
2.08
1.46
5.12
15
105
1.54
0.98
1.23
1.37
3.48
1.31
1.25
0.28
2.05
1.24
5.19
16
112
1.61
0.94
1.30
1.22
3.98
1.59
1.28
0.34
2.26
1.50
5.26
17
119
1.36
0.97
1.49
1.48
2.66
1.65
1.27
0.27
1.93
0.64
6.02
18
126
1.40
0.93
0.95
0.99
3.25
1.16
1.09
0.27
1.80
1.26
6.09
19
133
1.47
1.19
1.33
1.36
3.36
0.98
1.33
0.14
1.90
1.28
6.16
20
140
1.16
1.25
0.85
3.2*
3.46
1.03
1.09
0.21
2.25
1.72
6.23
21
147
1.16
1.23
1.26
1.17
5.56
1.53
1.22
0.05
2.75
2.44
6.30
22
154
1.63
2.02*
1.44
1.41
5.21
1.34
1.54
0.13
2.65
2.21
7.07
23
161
1.26
1.04
0.92
1.41
44.82**
1.36
1.07
0.17
1.39
0.04
7.14
24
168
1.85
0.9
BLQ
1.5
3.78
1.26
1.38
0.67
2.18
1.39
7.21
25
175
1.69
1
BLQ
1.29
3.46
1.3
1.35
0.49
2.02
1.25
7.28
26
182
1.42
1.09*
0.34
1.7
4.48
1.82
0.88
0.76
2.67
1.57
*re-analysis
**re-analysis, abnormal data
FIG. 14 is a graph of the in vivo plasma concentration of risperidone in the beagle dog study. The lower plot represents the average plasma concentration achieved in dogs implanted with one Carbothane® PC-3575A polyurethane implant (F.M. 620 psi). The upper plot represents the average plasma concentration achieved in dogs implanted with two Carbothane® PC-3575A polyurethane implants (F.M. 620 psi).
EQUIVALENTS
The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from the spirit and scope of the disclosure, as will be apparent to those skilled in the art. Functionally equivalent methods, systems, and apparatus within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. All references cited herein are incorporated by reference in their entireties.
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This invention is related to the use of polyurethane-based polymer as a drug delivery device to deliver biologically active compounds at a constant rate for an extended period of time and methods of manufactures thereof. The device is very biocompatible and biostable, and is useful as an implant in patients (humans and animals) for the delivery of appropriate bioactive substances to tissues or organs.
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FIELD OF THE INVENTION
This invention relates to a pleasant tasting antimicrobial, antiplaque mouthwash formulation, which maintains stability and clarity, free of alcohol, sugar and artificial sweeteners, that kills bacteria through antimicrobial action, thereby loosening plaque on teeth so that the plaque can be more easily removed during brushing or with additional dental rinsing, or by any other conventional method of cleaning the teeth.
DESCRIPTION OF THE PRIOR ART
U.S. Pat. No. 3,591,675, issued Jul. 6, 1971, discloses a brushless dentifrice consisting of carbon dioxide, ethyl alcohol, cetylpyridinium chloride and benzethonium chloride.
U.S. Pat. Nos. 4,666,708, issued May 19, 1987 and 4,657,758, issued Apr. 14, 1987, disclose a dental rinse for loosening plaque. This patent teaches a rinse including sodium benzoate and demonstrates that such a rinse is effective in loosening plaque. The composition employed in the patent includes: water, 65% to 95%; alcohol, 5% to 35%; sodium lauryl sulfate, 1% to 10%; and sodium benzoate, 2%.
While commercially successful, the formulation of the patent has proven to be ineffective in and/or not useable by certain individuals because of its content of alcohol, saccharine and dye.
U.S. Pat. No. 4,132,770, issued Jan. 2, 1979, discloses an aqueous oral product including sodium bicarbonate in solution, a flavor oil where desired, and at least one emulsifying agent for said flavor oil, and a dye if color is required; there may optionally be included a cosmetic alcohol, a humectant and sweetening agents.
U.S. Pat. Nos. 3,864,472, issued Feb. 4, 1975 and 3,947,570, issued Mar. 30, 1976, disclose lemon oil containing flavored mouthwash free from unpleasant tasting lemon oil degradation components comprising water, lemon oil, nonionic surfactant, humectant and buffering agent.
U.S. Pat. No. 4,132,770, issued Jan. 2, 1979 discloses a mouthwash with a pH of 8.0-9.3 including sodium bicarbonate and an emulsifying agent.
U.S. Pat. No. 4,150,151, issued Apr. 17, 1979 discloses essentiality a mouthwash with sodium dodecyl sulfate and sodium tetradecyl sulfate in various ratios.
U.S. Pat. No. 4,205,061, issued May 27, 1988, discloses a combination of antimicrobial ingredients including a halogenated salicylanilide and a quaternary ammonium compound.
U.S. Pat. No. 4,323,551, issued Apr. 6, 1982, discloses a mouthwash composition including cetylpyridinium chloride and tetrapotassium pyrophosphate.
U.S. Pat. No. 4,370,314, issued Jan. 25, 1983, discloses an antibacterial oral composition containing a cationic quaternary ammonium antibacterial antiplaque agent and an additive which reduces staining including alkali metal bicarbonate and benzethonium chloride or cetylpyridinium chloride.
U.S. Pat. No. 4,606,912, issued Aug. 19, 1986, discloses a mouthwash and a method for making same which includes calcium chloride, sodium fluoride, disodiummonohydrogen phosphate, glyceric acid and sodium chloride.
U.S. Pat. No. 4,861,582, issued Aug. 29, 1989, discloses dental compositions containing bicarbonate anion in combination with a monovalent anion such as fluoride, chloride or thiocyanate and methods of them in anticarogenic, antiplaque and antiperiodontopathaic therapy.
Other formulations of non-alcoholic mouthwashes are prone to cloud on aging because of the lack of alcohol for solubilization. In such prior art formulas, solubilizers were added in the flavoring; however, these solubilizers are esters which are not particularly stable. As the esters break down, the product clouds and, over time, shows precipitation.
Still other formulations using sodium bicarbonate and citric acid produced effervescence which resulted in undesirable by-products.
Poor taste in terms of lack of bite and a back note of a soapy nature has also been characteristic of many prior art non-alcoholic mouthwash preparations.
SUMMARY OF THE INVENTION
The present invention meets the need in the art of dental preventive medicine for a pleasant tasting oral hygiene formulation which maintains its clarity that can be safely used by those individuals who cannot or should not use a mouthwash containing alcohol, sugar, or artificial sweeteners.
In the formulation of the invention, no alcohol, sugar, artificial sweeteners are used. The formulation consists of water, glycerine, sodium benzoate, cetylpyridinium chloride, citric acid, maltol, xylitol and a mint/cinnamon flavor.
Water is the carrier. It must meet USP criteria for manufacture and have a pH of between 5.5 and 7.0. Glycerine serves as a humectant to provide body and a textual feel to the water. Glycerine also acts as the sweetener. Sodium benzoate is the anti-plaque and anti-calculus material. Cetylpyridinium chloride is a quaternary ammonium compound which is active against bacteria commonly found in the mouth. Flavor is added to produce a pleasant bite in the quantity of 85% mint and 15% cinnamon. Citric acid is also added to stabilize the pH of the formulation. The pH of the present invention is between 6.6±0.4. Maltol is a flavoring agent to impart a fresh flavor. Xylitol is used as a nutrient.
The present invention can be used by persons such as prison inmates, alcoholics or member of the police force or other persons who cannot subject themselves to alcohol for physiological, psychological, social or job related reasons. Of additional importance is the ability to use the present invention on chemotherapy patients.
A principal object of the present invention is to provide a mouthwash which assists in removing dental plaque. Another object of the invention is to provide an antimicrobial antiplaque mouthwash that destroys the microorganisms that play a key role in the etiology of plaque. A still further object and advantage of this invention is the provision of a mouthwash which aids in the reduction of caries formation and which inhibits the development of calculus and oral diseases associated with excessive plaque formation such as gingivitis and periodontitis.
A further object is the provision of a mouthwash which contains substances which enable its use by persons whose ingestion of alcohol must be controlled and/or eliminated while maintaining taste and clarity. Another object of the invention is to provide an effective plaque removing dental mouthwash which can be used by chemotherapy patients. A still further object of our invention is the provision of a mouthwash formulation which contains no artificial sweeteners. Another object of the invention is the provision of a non-alcoholic mouthwash which does not have problems in taste. A further object and advantage of our invention is the provision of a mouthwash which is stable with clarity.
These as well as further objects and advantages of the invention will become apparent to those skilled in the art from a review of the following detailed specification of our invention.
DETAILED DESCRIPTION OF THE INVENTION
In the formulation of the invention, no alcohol, sugar, or artificial sweeteners are used. The formulation consists of water, glycerin, sodium benzoate, cetylpyridinium chloride, citric acid, maltol, xylitol, a coloring agent and mint and cinnamon flavoring.
Plaque consists of about 80% live bacteria in a polysaccharide matrix. Therefore, it is desirable for a mouthwash to possess significant antibacterial properties in order to eliminate or retard the growth of the bacterial colonies present in plaque. The antimicrobials, sodium benzoate and cetylpyridinium chloride employed in our invention function to significantly reduce the number of bacteria in the oral cavity, thereby retarding development of plaque, caries and halitosis.
Sodium benzoate is an antimicrobial agent with antiseptic properties that reduces the number of plaque producing, odor causing bacteria in the oral cavity. Sodium benzoate also acts as a preservative and as an antiplaque agent.
Cetylpyridinium chloride is a quaternary ammonium compound which is an antimicrobial agent active against most common bacteria found in the mouth. Cetylpyridinium chloride also possesses antiseptic properties and acts as a detersive agent.
Citric acid is a buffering agent. By adjusting the hydrogen ion concentration, citric acid stabilizes the pH of the formulation. It also has been determined to have antimicrobial properties.
Glycerine serves as a humectant to provide body and a textual feeling to the liquid carrier. Glycerin also acts as a sweetener. Glycerine is included in 53 Fed. Reg. 2436 as safe and effective in oral health care drug products.
Maltol serves as a flavoring agent to impart a fragrant, caramel-like odor. We believe that maltol masks any soapy taste in our invention. Xylitol serves as a nutrient in various anticaries preparations such as chewing gums as reported in 1993 in the Journal of Dental Research, Vol. 72 (Special Edition), Abstract 1945, by Makinen, et al., and in HEALTH, July/August, 1993, page 14.
The mouthwash comprises a solution with water as the liquid carrier. The water meets USP criteria for manufacture, having a pH of between 5.5 and 7.0. The pH of the invention is 6.6±0.4, which is slightly acidic since sodium benzoate functions more effectively in an acidic solution.
Unlike other commercial mouthwashes, the present invention is free of alcohol. Alcohol is absorbed sublingually. It also has been documented that, although mouthwashes should be expectorated, alcoholics, including those who are members of the prison population, are likely to be abusers of any substance containing alcohol, including mouthwashes. Therefore, the present invention is suitable for safe use by alcoholics and others who cannot, or should not use alcohol because of physiological, psychological, social or job related reasons.
Of additional importance is the ability to use the present invention on chemotherapy patients. It is known that patients undergoing chemotherapy should not ingest even minute amounts of alcohols. Chemotherapy causes the parotid glands to produce an insufficient amount of saliva. In turn, an insufficient amount of saliva in the mouth contributes to the breakdown of tooth enamel (dental caries). Therefore, the present invention is suitable for safe use by those undergoing chemotherapy.
The present invention is free of sugar. Sugar is converted in the mouth to acid, a major factor in the etiology of dental caries and in the formation of plaque. The metabolization of sugar by bacteria produced toxins and waste products that exude into the gums, inflaming them, thereby initiating gum disease. It is also known that sugar should not be ingested by diabetics and that sugar has other deleterious effects. Therefore, the present invention is suitable for safe use by diabetics and other who cannot, or should not, use sugar.
The present invention is free of sodium saccharin. Sodium saccharin, like alcohol, is absorbed sublingually. Sodium saccharin has been found to be carcinogenic in laboratory animals, specifically-rats and mice. Therefore, the present invention is suitable for safe use by those who cannot, or should not use saccharin.
The mouthwash is applied to the surface of the teeth, gums and oral cavity by using two tablespoons of the oral rinse, circulating it throughout the mouth for a minimum of ten seconds in order to thoroughly soak the teeth and gums, then discharging the oral rinse from the mouth. The oral rinse should not be swallowed. Immediately thereafter, the teeth should be thoroughly brushed, using a conventional toothbrush and dentifrice. Regular and correct use of this invention is intended to significantly reduce the number of bacteria present in the oral cavity and to inhibit the formation of plaque. This, in turn, will help prevent or ameliorate plaque associated oral diseases, such as gingivitis and periodontitis, and reduce the incidence of dental caries.
The invention underwent analytical testing--by extraction and titration--to ensure that cetylpyridinium chloride and sodium benzoate in the non-alcoholic mouthwash is stable for a period of at least three months in sealed bottles at ambient temperatures of up to 40° C. at 70% relative humidity.
Microbiological testing of the invention was undertaken to ensure that the mouthwash is free from bacteria, mold and yeast. In compliance with the guidelines set forth in US Pharmacopoeia (Vol. 21), the mouthwash was inoculated with various organisms and a rapid reduction, both in their number and activity, was observed. In the sample tested, the TBS/gm (ml) (total bacteria count) was less than 10; there was no growth in the broth enrichmen t gram stain test; the TMC-TYC/gm (ml) (total mold -yeast count) was less that 10, and there was no growth in the TMC-TYC broth. For group I bacteria, group II bacteria, and group III fungi-yeast, the percentage of reduction was 99.9%, at the end of 24 hours and 99.9% at the end of one week. The invention passed USP XXII challenge testing.
The mouthwash formulation of the invention comprises a solution with a pH of 6.6±0.4. The liquid carrier is water (86.15), which meets USP criteria for manufacture and has a pH of between 5.5 and 7.0. The pH of the invention is 6.6±0.4, which is slightly acidic since sodium benzoate functions more effectively in an acidic solution.
Dissolved in the liquid carrier are the following components in the following weight percents; glycerine, FCC (19.00); sodium benzoate, FCC (0.30); cetylpyridinium chloride, USP (0.045); citric acid, FCC (0.10); maltol, FCC (0.10); xylitol (1.00); mint/cinnamon flavor (0.40, 85% mint, 15% cinnamon); and FDC red #40 (0.0012). These ingredients may vary by 15% ±.
This preparation was evaluated in a twenty-one day controlled use test. The preparation evaluated was prepared in accordance with the invention with a pH of 6.6 as follows: water, (86.15); glycerine, USP (12.50); sodium bicarbonate, USP (0.50); sodium benzoate (0.30); cetylpyridinium chloride (0.045); and citric acid, USP (0.10) and flavoring agents, spearmint and peppermint. The control was a flavored water rinse.
The oral rinse and the control were distributed to separate groups containing eight subjects each. The subject's ages ranged from 18 to 57 years. Baseline oral examinations were performed on all subjects in this study. Standard evaluations were done using mouth mirrors, explorers and potassium hydroxide disclosing tablets.
The scoring for gingivitis was based upon the papillary marginal-gingivitis index (PMGI Loe & Silness). The PMGI scores gingivitis on papillar and margins on the facial and lingual gingiva of natural teeth. In this method, the severity of gingivitis is expressed by the average of individual scores for each subject divided by the number of papillary and marginal units examined per subject. The study commenced with a PMGI score of at lease 2.0 prior to start. This particular scoring range exhibits moderate inflammation, moderate glazing, redness, edema and enlargement.
The plaque scoring system (Quigley & Hein) is a quantitative estimate of the amount of plaque present on the buccal, labial and lingual surfaces of the teeth. All subject examined had some level of plaque present. When this was not attainable, subjects were to refrain from brushing for two days prior to re-examination.
All subjects were instructed in the proper techniques for brushing teeth and the use of the mouthwash. Two brushings were to be performed daily followed by a double water rinse. Participants were instructed to rinse twice daily with the oral rinse or water control using measured 20 milliliter portions for 30-second periods. The rinse was to occur after brushing and a double water irrigation.
The results of this evaluation are set forth in the following where PI is the plaque index and PMGI is the gingivitis index.
______________________________________ PI PMGI______________________________________BASELINE RESULTSOral Rinse 1.88 2.38Placebo 2.75 2.13SEVEN DAY RESULTSOral Rinse 1.88 2.38Placebo 2.75 2.25TWENTY-ONE DAY RESULTSOral Rinse 1.25 1.50Placebo 2.88 2.25% REDUCTIONOral Rinse 33.5% 36.9%Placebo -- --______________________________________
Among the factors that can significantly influence a solution's microbial activity is its pH. Extremes of a solutions' acidity or alkalinity effectively limit growth of microorganisms, pH 4.5 to 9 being a limiting range for many organisms. Furthermore, for many weak acids, antimicrobial activity is primarily attributable to the undissociated molecule; it is the undissociated acid molecules that are responsible for antimicrobial activity since they are able to pass through cell membranes more readily than the charged molecules.
The effect of pH on the activity of certain antimicrobial compounds is well known (Albert, 1951). It has been demonstrated that only the undissociated molecules of benzoic acid (sodium benzoate) are toxic to microorganisms; that the concentration of non-ionized molecules is dependent on the pH of the medium (Rahn and Conn, 1944); and that benzoic acid (sodium benzoate) is a more effective antimicrobial agent in acidic rather that neutral solutions. It has been further demonstrated that benzoic acid (sodium benzoate) is effective against bacteria in acid media at concentrations of 0.1% and in neutral media at concentrations of 0.2% (Gabel, 1921). The level of sodium benzoate in the invention is 0.30. The antimicrobial action is further potentiated by the addition of cetylpyridinium chloride.
The use of solvents other than water can influence antimicrobial activity by virtue either of the inherent toxicity of the solvent or through its effect on thermodynamic activity of antimicrobial agents. A nontoxic solvent such as glycerine appears to have little negative influence on microbial growth unless it is used in concentrations of 20% to 50% (Barr and Tice, 1957).
The level of glycerine in the mouthwash is carefully balanced in order to provide the preferred amount of body to the solution yet not interfere with the antimicrobial activity of the invention.
In order to advantageously enhance the antimicrobial properties of the mouthwash, sodium benzoate is included in the formulation. Sodium benzoate--the sodium salt of benzoic acid--is an antimicrobial agent with antiseptic properties that effectively reduces the number of bacteria in the oral cavity; sodium benzoate also functions as a preservative and an antiplaque agent.
Cetylpyridinium chloride, a quaternary ammonium compound, is an antimicrobial agent active against staphalococcus and streptococcus species as well as other bacteria. Cetylpyridinium chloride also possesses antiseptic properties and acts as a detersive agent. Cetylpyridinium chloride also acts as a potentiator of the antimicrobial properties of sodium benzoate. Cetylpyridinium chloride has been shown to be a powerful, rapidly acting germicide against test bacteria in vitro (Helmsworth and Hosworth, 1045), particularly against staphylococci. Cetylpyridinium chloride killed Pseudomonas aeroginosa in 10 minutes at 37° C. in a minimum dilution of 1:5800, which was a more concentrated solution than was required to kill a variety of other gram-negative bacteria and cocci (Quisno and Foster, 1946). Work with cetylpyridinium chloride has illustrated several common characteristics of quaternary ammonium compounds, such as their greater activity against gram-positive bacteria than against gram-negative bacteria (Quisno and Foster, 1946).
The following table shows the germicidal activity of cetylpyridinium chloride aqueous solution at 37° C.
______________________________________GERMICIDAL ACTIVITY OF CETYLPYRIDINIUMCHLORIDE AQUEOUS SOLUTION Average Critical Killing Dilution in Number Terms of Active of Strains Ingredients at 37° C.Organism Tested (No Serum)______________________________________Staphyloccus aureus 5 1:83,000Staphyloccus albus 2 1:73,000Streptococcus viridans 1 1:42,500Streptococcus hermolyticus 2 1:127,500Neisseria catarrhalis 2 1:84,000Diplococcus pneumoniae 1 1:95,000Pseudomonas aeruginosa 2 1:5,800Klebsiella pneumoniae 2 1:49,000Coronebacterium diptheriae 1 1:64,000Mycobacterium phlei 1 1:1,500Eberthella typhosa 5 1:48,000Escherichia coli 2 1:66,000Proteus vulgaris 2 1:34,000Shigella dysenteriae 1 1:60,000Shigella paradynsenteriae 2 1:52,000(Flexner)Shigella paradysenteriae 1 1:49,000Shigella sonne 2 1:68,000______________________________________
The mouthwash is prepared by mixing the active ingredients together to form a homogeneous solution. The manner of making the invention is illustrated in the following example. A mouthwash was formulated from the following components in the indicated weight percentages:
______________________________________COMPONENT WEIGHT %______________________________________Phase A-1Water 79.0538Glycerine, FCC 19.00Phase A-2Sodium Benzoate, FCC 0.30Citric Acid, FCC 0.10Cetylpyridinium chloride, FCC 0.045Phase BFlavor (cinnamon and mint) 0.40maltol, FCC 0.10xylitol 1.00FDC red #40, 1% solution 0.12______________________________________
The main mixing vessel was a clean, sanitized, stainless steel (304 or 316 - grade) steam-jacketed manufacturing tank, equipped with a lightning type mixer. The tank was charged with water, which was mixed with moderated agitation in order to prevent foaming, and heated to a temperature no higher than 60° C. The phase A-2 ingredients then were added very slowly, in sequence, and cooled gradually until all powdered materials had dissolved, After the temperature had dropped to below 50° C., the glycerine (a Phase A-1 ingredient) was added to the batch. A second, clean, sanitized, stainless steel vessel was charged with the remainder of the water; the temperature of the water was no higher than 40° C. After further cooling, the batch was clear. The resultant product was uniform in appearance and did not separate, even after prolonged standing at room temperature.
Further modifications to the invention may be made without departing from the spirit and scope of the invention; accordingly, what is sought to be protected is set forth in the appended claims.
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A pleasant tasting antimicrobial mouthwash formulation which maintains clarity for removal of dental plaque where no alcohol, sugar, artificial sweeteners are used making it suitable for safe use by alcoholics, diabetics, persons under medical treatment or taking medications which prelude the use of alcohol, hospitalized patients, prison inmates, minors and all other persons who can not or should not subject themselves to alcohol, sugar, or artificial sweeteners. The formulation consists of water, glycerin, sodium benzoate, cetylpyridinium chloride, citric acid, maltol, xylitol, a flavoring agent to give a pleasant though biting taste, and a coloring agent.
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BACKGROUND OF THE INVENTION
The invention relates to a floor consisting of individual two-dimensional elements.
The invention is intended, in particular, for temporarily installed floors, which can be removed following installation and use, and reused again. Such floors are required, for example, for use in exhibitions. It was previously not possible to configure level and quality floor surfaces with a high load-carrying capability, especially when thin, and therefore light natural stone panels, are used.
In the state of the art, floors comprising textile coverings, which can be removed following use, are known. In this connection, the covering is removable from the floor without leaving a residue and without damaging the floor covering.
According to DE 36 00 807 C2, a method is disclosed for this purpose, for which a plastic layer is disposed on both sides of a backing material, at least one side of which is glueable, impermeable to the adhesive and resistant to water.
For use under high loads and for external use, it is known that stone, concrete or ceramic elements may be laid in mortar or on corner supports. According to DE 197 37 097 C2, a system is known, for which panels are used, and which are laid individually next to one another, or with the help of connecting plates on which the floor covering is applied.
When used in the usual manner for achieving the strength required, natural stone panels are relatively thick and heavy, and therefore cumbersome to transport. For this reason, they are not generally suitable for repeated use. Because of the danger of breakage, thin natural stone panels, which are therefore easily transported, must be glued onto a level substrate or laid in a bed of mortar, and therefore also, are also not suitable for temporary and repeated use.
It is, therefore, an object of the invention, to provide a floor configuration of high strength, comprised of individual elements which are light and easily transported, as well as easily removable, and which can be used repeatedly.
It is a further object to indicate a floor panel unit with a high load-carrying capability of individual floor panels being lightweight and easily transportable and easy to assemble and disassemble, whereas the necessary construction elements are easily removable and re-usable at different times. Moreover, the floor panel unit should be pleasantly passable on foot and allow a re-use in multiple applications.
SUMMARY OF THE INVENTION
Pursuant to the invention, these objectives are accomplished by use of individual floor panels of multi-layer construction, each comprising a pressure-resistant and wear-resistant upper layer and a pressure-resistant lower layer attached to said upper layer. The lower layer includes horizontal grooves at vertical edges thereof in which fastening rails are fixable. The fastening rails include horizontal reception grooves each which includes undercuts at upper and lower inner surfaces thereof. Connecting strips, each include horizontal legs which are formed elastically by provision of a horizontal slot extending between a pair of leg segments which define each of said horizontal legs, the leg segments including thickened portions thereon which are vertically extended from a remainder of said leg segments in opposed directions. The thickened portions are configured to engage the undercuts at the upper and lower inner surfaces of the horizontal reception grooves of the fastening rails for providing a positive, but detachable connection with adjacent ones of the individual floor panels, wherein the adjacent ones of the individual floor panels are thereby connectable together by a shared one of the connecting strips.
Due to the multilayer construction of the individual panels, with, in each case, a thin panel on the upper side and, below this, a pressure-resistant light material layer, which preferably consists of a foamed material, a light floor element with a high quality surface and sufficient strength is realized.
Due the arrangement of the peripheral grooves at the edges of the layer of light material and of connecting strips in the grooves between adjacently placed multilayer panels, the securing of the floor elements against shifting in the joint direction, as well as avoidance of offsets between adjacently laid multilayer panels, is accomplished in an easy manner. Because thin, two-dimensional sheathing of high strength and high modulus of elasticity is glued between the upper panel and the light material layer, a very high strength of the floor elements is realized, even when very thin panels and, therefore, very light floor elements are used. Such a high strength of the floor elements ensures a sufficient safety against fracture, even in the case of localized stresses which occur, for example, when shelves or cabinets, which are supported at points, are arranged. Moreover, the floor elements do not need to be laid in a bed of mortar or glued to a substrate.
In accordance with another embodiment, the floor panel unit according to the invention comprises a number of two-dimensional multilayer floor panels, each including a thin pressure-resistant and wear-resistant upper layer and a pressure-resistant support member. Pursuant to the further embodiment of the invention, each of the directly adjacent disposed floor panels is connected with each other in a corner region and/or in an outer edge area with a two-dimensional connecting element, which is located below the floor panels. The two-dimensional connecting element features vertically disposed outer legs engaging with material gaps, which are located in an undersurface of the support members and which correspond to the outer legs.
Due to the construction of individual floor panels with connecting elements, and outer legs being located on the latter and being preferably symmetrical to each other, a stable arrangement of floor panels with a constant distance between each other is easily accomplished avoiding offsets between floor panels. Furthermore, such connection being preferably force-closed and/or form-closed enables an easy assembly and, primarily, an easy disassembly of the floor panel unit, as the floor panels can be removed separately. As a result, there is the advantage of exchangeability of individual floor panels, for instance because of damages or a desired change of design.
Moreover, lightweight floor panels can be produced with high-grade floor surfaces and a high load-carrying capability. This is accomplished by the multilayer construction of the individual floor panels with at least one thin upper layer on the upper surface and a preferably glued pressure-resistant support member being disposed beneath and being particularly formed of lightweight material.
In a preferred version of the embodiment of the invention, the outer legs are radial, right-angled and/or parallel to each other, such that another increase of stability of the connection with support members is achieved by using multiple parallel disposed legs.
Additionally, according to a further embodiment of the invention, material grooves are each placed in the undersurface of the support members, whereas a material surface, being enclosed by these material grooves, corresponds with gaps being placed in an area of the connecting element. Besides another increase of securement against shifting of the connecting elements on the support members, and besides the stability of the connection, a flush arrangement of the connecting elements at the undersurface of the floor panels or, rather at the support members, is achieved, on the one hand avoiding an additional elevation of the floor panel unit and, on the other hand enabling a maximum supporting surface, and thus an increased stability of the entire floor panel unit.
A preferred embodiment of the invention provides that the outer legs are compressible into the material gaps of the support members and/or provides that material surfaces of the support members, being enclosed by material grooves, are compressible into the gaps of the connecting element. The arising press fit enables an arrangement and connection of the floor panels being free from play.
A further intention provides that primarily vertical and right-angled joint fillets are fastened into a middle area of the connecting element, enabling a constant and definable lateral dimension of a joint between individual floor panels.
According to a further embodiment of the invention, a height of the joint fillets is smaller or equal to the thickness of the floor panels, so that these joint fillets do not tower over the floor panels.
Alternatively, the height of the joint fillets is smaller or equal to a thickness of the support member, if the joint fillets can be disposed in recesses, which correspond to the joint fillets and which are placed in vertical lateral faces of the support members. Thus, a jointless laying of the floor panels is advantageously possible.
Furthermore, jointless laying or rather arrangement of floor panels is achievable thereby that the upper layer is wider and/or longer than the related support member, whereas the upper layer towers over the vertical lateral face of the support member so that the joint fillets are covered by the upper layer.
It is particularly advantageous that the undersurface of the support members additionally features burling-like disposed material high spots, which also enables in a functional way a laying of the floor panel unit on undefined ground, which is especially uneven, as material high spots adjust unevenness.
Moreover, preferably channel-like grooves are placed into the undersurface and/or upper surface of the support members. One the one hand, these grooves aim to conduct condensation dew and/or humidity, on the other hand, conduits of a floor heating are capable of being integrated especially into channel-like grooves placed into the upper surface of the support members, or rather, the channel-like grooves are usable as conduits. Furthermore, especially channel-like grooves being placed in the undersurface are suitable for housing power cords, so that these power cords can be laid outside a field vision and do not negatively influence the outer impression of the floor panel unit.
Additionally, according to a particular preferred embodiment of the invention, guide elements are disposed at the floor panel and/or at the connecting element, via which joint strips can be fixed between the floor panels. This is a simple way to fasten joint strips, which can be advantageously detached, so that joint strips can be simply assembled, disassembled and replaced.
The invention is explained in greater detail in the following with reference to examples shown in the accompanying drawings. In all figures, corresponding parts have the same reference designators.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a multilayer panel in accordance with an embodiment of the invention;
FIG. 2 is a perspective view of a connecting strip in accordance with an embodiment of the invention;
FIG. 3 is a cross-sectional perspective view of a total arrangement of a floor;
FIG. 4 shows a detail of the connecting site;
FIG. 5 schematically shows an underside perspective view of a two-dimensional multilayer floor panel according to another embodiment;
FIG. 6 schematically shows a connecting element in a top view;
FIG. 7 schematically shows the connecting element according to FIG. 6 in a perspective view;
FIG. 8 schematically shows the floor panel according to FIG. 5 with the connecting element, according to FIG. 6 , placed at the floor panel;
FIG. 9 schematically shows two floor panels being connected to three fillets via a square connecting element;
FIG. 10 schematically shows a floor panel and a square connecting element with five fillets;
FIG. 11 schematically shows a top view of an undersurface of a floor panel, featuring burling-like disposed material high spots; and
FIG. 12 schematically shows a perspective view of the undersurface according to FIG. 11 .
DETAILED DESCRIPTION OF THE INVENTION
The section through an inventive, multilayer panel, is illustrated in FIG. 1 , and shows a thin panel 1 of natural strength. A carbon fiber-reinforced plastic fabric of small thickness is glued two-dimensionally to an underside of the panel 1 by means of an epoxide resin, as a two dimensional sheathing 2 . In addition to natural stone, the thin panel 1 may be comprised of glass, wood, or metal. In comparison with the natural stone panel, etc., the carbon fiber-reinforced plastic fabric has a relatively high modulus of elasticity. The tensile strength and the compression strength of the carbon fiber-reinforced plastic fabric are clearly greater than the compression strength of the natural stone. Beneath the carbon fiber-reinforced plastic fabric, a pressure-resistant foam layer 4 , which comprises an extruded and hydrophobized Styrofoam, is glued two-dimensionally. Due to the multilayer construction shown, a multilayer panel of low weight and high bending strength is achieved. In the case of an appropriate construction, the sheathing 2 is disposed within the layer 4 of light material. The sheathing elements advantageously can also be introduced, owing to the fact that the slots for accommodating strip-shaped sheathing 2 are incorporated in the layer 4 of lightweight material. For example, the slots can be incorporated in pre-manufactured lightweight panels before the latter are combined with the thin panel 1 and the strip-shaped sheathing 4 is subsequently glued into these slots.
Peripheral grooves 3 , which accommodate the connecting strips 9 , are disposed at all four edges of the layer 4 of light material of the square floor panel. The panels may have edge lengths of 200 to 2200 mm. Preferably, squares with a length of 300 to 500 mm and a thickness 10 to 20 mm are used.
Such a connecting strip 9 is shown in FIG. 2 . The connecting strip 9 has at least two horizontal legs 9 . 1 . The embodiment, shown in FIG. 2 , is similar to a T-shaped profile and has two horizontal legs 9 . 1 and an additional vertical leg 9 . 2 . The thickness of the horizontal legs 9 . 1 is slightly less than the width grooves 3 ; in the longitudinal direction of the profile, profilings, in which the horizontal legs 9 . 1 are clamped securely in the grooves 3 and which thus serve to connect adjacently disposed multilayer panels, are disposed at the horizontal legs 9 . 1 . To facilitate the assembly, it is advisably to provide the ends of the horizontal legs 9 . 1 with a conically constructed chamfered edge. The vertical legs 9 . 2 maintain a defined vertical joint width between the multilayer panels.
FIG. 3 shows an asymmetrically represented section of an overall arrangement of a floor with several multilayer panels, which are connected in each case by connecting strips 9 . The multilayer panels are laid on a level substrate; the substrate consists of a lower sheet 8 , over which a rapidly setting jointless floor 7 is cast. An upper sheet 6 is disposed over the jointless floor 7 . The floor is bounded at the sides by an L-shaped metal, angled profile 5 , the horizontal leg of which is covered with the jointless floor 7 . The angle profile 5 is fixed in the substrate by this covering. At the side facing the floor, the vertical leg of the angle profile 5 is provided with a compressible sealing tape, which prevents the mortar emerging from the frame. The mutual connection of the connecting strips 9 , which are disposed in the two joint directions at the crossing points of joints between the multilayer panels, is not shown in the Figure.
FIG. 4 explains a detail of a connecting site, for which there are additional fastening rails 10 , which have a groove engaged by the horizontal legs 9 . 1 of the connecting strips 9 , in the side surfaces of the layer 4 of light material. Advantageously, the horizontal legs 9 . 1 are formed elastically by a slot and are provided at the end with thickenings, which engage corresponding undercuts at the inner surfaces of the fastening rails and thus make possible a positive, but detachable connection and, with that, a secure and gap-free arrangement of adjacent panels.
At the same time, it is also possible that the vertical legs 9 . 2 are provided at their upper side with colored edge strips 11 of an elastic plastic, which fulfill decorative tasks, as well as improve the sealing. Aside from a flat shape, shown in FIG. 4 , the surface of the edge strip 11 can also have a raised shape, as shown in FIG. 4 b , or be constructed as a fillet, as shown in FIG. 4 c . Furthermore, it is possible to use the versions of the connecting strip 9 without a vertical leg 9 . 2 . These embodiments, suitable especially for use for exterior patio panels, are shown in FIG. 4 d . The connecting strip consists here only of the two horizontal legs 9 . 1 , which are provided with openings. By these means, it becomes possible to discharge water from the surface of the panels, which drains through the gap between adjacent panels and can be discharged through the connecting strip 9 .
A two-dimensional multilayer floor panel 21 according to another embodiment of the invention is illustrated in FIG. 5 , viewed in perspective from an undersurface thereof, comprises a support member 12 and an upper layer 13 . The support member 12 is preferably made of a pressure-resistant and contemporaneously lightweight material, which is particularly a matter of a form of foam, as for example, expanded polypropylene, polystyrene or other suitable lightweight materials with a high load-carrying capability, as e.g., wooden polypropylene or glass-fiber reinforced plastic.
Upper layer 13 is made of natural stone, although upper layer 13 can also be made of glass, wood, metal, plastic or another stable material. Therefore, a combination of different materials is possible. Upper layer 13 and support member 12 are two-dimensionally glued together, whereas preferably an epoxy resin or other glues are usable as glue.
A joint-gentle walk and therefore a high comfort while walking can be realized because of the multilayer construction of the floor panel.
In accordance with a further development of the invention, which is not described in greater detail, an additional intermediate layer, made of, for example, carbon fiber reinforced plastic, is disposed between support member 12 and upper layer 13 . Compared to the natural stone panel, this intermediate layer features a high modulus of elasticity. Tensile strength and compression strength of the intermediate layer is considerably higher than the compression strength of the natural stone. Due to such a multilayer construction, a high tensile bending strength is achieved, if the weight of the multilayer element is light.
The intermediate layer can continuatively be also made of a ceramic layer. Ceramic material advantageously features a very high load-carrying capability so that floor panel 21 features a high load-carrying capability and stability, even if a very thin upper layer 13 is used. Because of this very thin construction of upper layer 13 , a strongly reduced total weight of floor panel 21 is achieved, particularly if the used material is natural stone.
Air humidity arising by the ground or water entering from upper layer 1 ′ is guided in channel-like crossing grooves 12 . 1 being placed in the undersurface of support member 12 to the edge of the floor surface.
In a further embodiment of the invention, which is not described in greater detail, channel-like grooves 12 . 1 are also placed in the upper surface of support member 12 , in which condensation dew arising at the undersurface of upper layer 13 can advantageously be evaporated and discharged. Furthermore, grooves being placed in the upper surface of support member 12 are suitable for guiding a medium, e.g. warm air, so that a floor heating is realizable. Channel-like grooves 12 . 1 can lie on top of each other in a parallel or congruent way regarding their upper surface and undersurface or they can be placed offset.
According to the invention, a two-dimensional connecting element 14 described in greater detail in FIGS. 6 and 7 is intended, in order to connect multiple floor panels of this kind. This connecting element is disposed beneath floor panels 21 , that is to say between floor panels 21 and ground, and it is round or rather circular in the example of the invention. Connecting element 14 is for instance made of plastic.
Thereby, connecting elements 14 are connected to the undersurface of support member 12 in a force-closed and/or form-closed way, whereas every connecting element 14 consists of multiple vertically disposed outer legs 14 . 1 , which are radial and symmetric to each other. In the shown example of the invention there are particularly four outer legs 14 . 1 . Thereby, one outer leg 14 . 1 each is disposed in a quarter circle.
Moreover, material gaps 12 . 2 are placed at the angles of the undersurface of support members 12 , which correspond to the outer legs 14 . 1 of the connecting element 14 . Outer legs 14 . 1 engage with these material gaps 12 . 2 .
In order to achieve another increase of stability of the connection between support members 12 and connecting elements 14 , material grooves 12 . 3 are placed each in support members 12 , whereas a material surface 12 . 4 being enclosed by material grooves 12 . 3 corresponds with gaps 14 . 2 being placed in an area of connecting element 14 . Thereby, gaps 14 . 2 being placed in connecting elements 14 are disposed with each an outer leg 14 . 1 in a quarter circle. Furthermore, material grooves 12 . 3 and gaps 14 . 2 corresponding to these material grooves 12 . 3 advantageously result in the fact that the undersurfaces of support members 12 and the connecting elements 14 form a layer so that connecting elements 14 do not tower over the undersurface of connecting elements 14 .
Therefore, as shown in FIG. 8 , four floor panels 21 each are connectable with each other using a connecting element 14 , whereas each angle of floor panel 21 corresponds with a quarter circle of connecting element 14 . Thereby, floor panels 21 are in such a manner connectable with each other that a total connection of floor panels 21 is characterized by continuous going joints and/or abutting edges.
As the floor panel unit consists of multiple floor panels 21 , the total floor panel unit is frost-resisting because a dilatation of floor panels 21 is possible, if freezing water enters from a position beneath or between floor panels 21 .
According to a further embodiment of the invention, which is not described in greater detail, material gaps 12 . 2 and material grooves 12 . 3 are also disposed between relative angles of connecting element 12 , whereas two quarter circles each, that is to say one semicircle, is formed, in order to achieve also an offset arrangement of floor panels 21 and hence an uncontinuous going of joints and/or abutting edges.
In accordance with an advantageous further embodiment of the invention, connecting elements 14 , material gaps 12 . 2 corresponding to connecting elements 14 and being placed in support members 14 , and material grooves 12 . 3 are in such a manner constructed that connecting elements 14 are compressible into support members 12 so that a connection being free from play and stable arises.
Additionally, connecting elements 14 feature vertical and right-angled joint fillets 14 . 3 in a middle area. A lateral dimension between floor panels 21 can be preset with these joint fillets 14 . 3 . These joint fillets 14 . 3 are advantageously in such a manner disposed and constructed that a press fit arises between these joint fillets 14 . 3 and support members 14 so that joint fillets 14 . 3 contribute to another increase of stability of the connection of floor panels 21 .
In the shown example of the invention, a height of the joint fillets 14 . 3 is smaller than a thickness of support members 12 . Therefore, it is possible to achieve a jointless arrangement of floor panels 21 without distance to the floor panels, that is to say a directly adjacent arrangement of floor panels 21 is possible, even if joint fillets 14 . 3 are used. For this purpose it is possible to place recesses in vertical lateral faces of support members 12 , which correspond to joint fillets 14 . 3 , depending on the case of practice, in a manner not described in greater detail, so that upper layers 13 of individual floor panels 21 can be placed directly and without distance to each other.
Alternatively, it is also possible that, depending on the case of practice, upper layers 13 are wider and/or longer than the each related support member 12 , so that upper layers 13 can be disposed in a way that they tower over vertical lateral faces of support member 12 .
Several visual effects can be achieved by placing recesses corresponding with joint fillets 14 . 3 into only two vertical opposing lateral faces of support members 12 or just by using a longer or wider construction of upper layer 13 . So, it is possible that joints go for instance just to one spatial direction, for example crossways, whereas floor panels 1 are jointlessly disposed in longitudinal direction.
In another embodiment of the invention, which is not described in greater detail, guide elements are disposed at floor panels 21 and/or at connecting elements 14 . Joint strips can be fastened between floor panels 1 with these guide elements. Thereby, guide elements are constructed as for instance a U-shaped or V-shaped profile, in which joint strips corresponding to this profile engage or preferably lock in place. Joint strips are preferably made of plastic and can be produced in several colors. Consequently, several visual effects can be simply achieved, again. Moreover, joint strips are easy to assemble and disassemble so that they are easily and quickly removable.
FIG. 9 shows two floor panels 21 being connected to each other by a connecting element 14 featuring a square area and legs 14 . 1 being parallel to each other in every quarter circle, whereas directly adjacent and right-angled legs 14 . 1 build each a continuous frame-like leg.
Regarding the middle of connecting element 12 , on which a cuboid-formed leg 14 . 4 is disposed, four vertical disposed joint fillets 14 . 3 are constructed, so that a defined distance between floor panels 21 is realizable.
Support members 12 of floor panels 21 consist of material gaps corresponding to legs 14 . 1 and cuboid-formed legs 14 . 4 , not described in greater detail, whereas material gaps, legs 14 . 1 and joint fillets 14 . 3 are preferably in such a manner constructed that connecting elements 14 are compressible into support members 12 of floor panels 21 .
A floor panel 21 and a square connecting element 14 are illustrated in FIG. 10 , whereas this connecting element 14 consists of four parallel legs 14 . 1 each in every quarter circle, on the contrary to the arrangement shown in FIG. 9 .
Regarding a construction of floor panels 21 and connecting elements 14 according to FIGS. 9 and 10 , connecting elements 14 are preferably made of the same material as support members 12 , that is to say they are for instance made of a form of foam.
A particular profitable embodiment of the invention is shown in FIGS. 11 and 12 , whereby an undersurface of support member 12 features burling-like disposed material high spots 12 . 5 . These material high spots 12 . 5 are regularly disposed and constructed as a circular cone. However, alternatively also an irregular arrangement and other shapes are possible, as for example a shape of a pyramid.
In a particular profitable manner, material high spots 12 . 5 result in the fact that floor panels 21 can also be laid on uneven ground or other surfaces, as floor panels 21 adjust unevenness. For this purpose, material high spots 12 . 5 are not resiliently constructed so that these material high spots 12 . 5 irreversibly change their shapes, if they were laid on uneven ground, in such a manner that unevenness is compensable. For this purpose, particularly the use of material of polystyrene is suitable. In addition, a further improved sub ventilation of floor panels 21 and an improved discharge of humidity are ensured because of material high spots 12 . 5 .
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A multi-layer floor panel unit, which can be assembled with a plurality of similar units to form a floor which is capable of repeatedly being disassembled and reassembled at different times and/or in different locations, includes a pressure-resistant and wear-resistant upper layer; a pressure-resistant lower layer, attached to the upper layer, and having grooves at vertical edges of the lower layer; and connecting strips in the grooves, for connecting adjacent multi-layer floor panel units, the connecting strips having horizontal legs with thickened portions thereon, the thickened portions being for clamping the connecting strips in the grooves.
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[0001] This application claims the benefit of U.S. Provisional Application No. 60/561,639, filed Apr. 13, 2004.
TECHNICAL FIELD
[0002] This invention relates to food preparation centers, and more particularly to food preparation centers including refrigerated storage and an oven.
BACKGROUND
[0003] It is desirable to cook foods quickly while also obtaining a proper texture in the foods after cooking. Standard ovens and brick ovens tend to give the proper texture but take longer than desired. Microwave ovens are known for fast cooking, but bread dough and other foods do not achieve proper texture when cooked in a microwave. Convection ovens may achieve the proper texture for some foods and are quicker than standard ovens, but are not fast enough for walk-up service as in a convenience store or fast food restaurant.
[0004] As an example, there are no commercial ovens known that can cook a raw pizza of standard size from a raw state to a properly browned and crisp state in less than four minutes.
[0005] Additionally, it is desirable to have a compact preparation center that allows for the refrigerated storage for all necessary components of a food product as well as the means to prepare and cook the food products in a timely fashion.
SUMMARY
[0006] A compact scalable food preparation center is adapted for the preparation of custom ordered pizzas on a walk-in or drive-through basis. The center has a base unit with a food preparation surface, a refrigerated storage unit under the food preparation surface, and a refrigerated topping storage area on the food preparation surface, the topping storage area having a cover. One or more ovens, which may be similar to the oven described by U.S. patent application Ser. No. 11/029,754 is positioned on top of the base unit with a solid cooking surface and heating elements spaced above the solid cooking surface. The oven is controlled to cook non-frozen raw pizzas and partially cooked pizzas with toppings.
[0007] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a front view of a food preparation center.
[0009] FIG. 2 is a top view of the food preparation center of FIG. 1 .
[0010] FIG. 3 is a side view of the food preparation center of FIG. 1 .
[0011] FIG. 4 is a perspective view of an alternative food preparation center.
[0012] Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
[0013] As shown in FIGS. 1, 2 and 3 , a food preparation center 10 includes a base unit 12 with a food preparation surface 14 and a storage area 16 that may be refrigerated. A topping storage area 18 may be recessed into the food preparation surface 14 . The topping storage area 18 may also be refrigerated, non-refrigerated, and/or covered by a topping storage cover 19 . An oven 20 is positioned on top of the base unit 12 . Peel storage 22 is attached to the side of base unit 12 , and peels 24 are stored in peel storage 22 . As shown in FIGS. 1, 3 and 4 , two ovens may be included in the food preparation center 10 . Multiple ovens may be configured in a stacked or side-by-side configuration, or any other suitable configuration. Topping storage cover 19 may be connected to the food preparation surface 14 by hinges or simply placed over the topping storage area 18 to reduce or prevent contamination and/or reduce the amount of cooling necessary to maintain the refrigeration of the contents of the topping storage area 18 .
[0014] An implementation of one type of oven 20 is described in more detail in U.S. patent application Ser. No. 11/029,754, with the title “Air Control for a Brick Oven,” as well as U.S. Pat. No. 6,114,663, U.S. Pat. No. 6,355,914, and U.S. patent application Ser. No. 10/077,250, all incorporated herein by reference. As such, the illustrated oven 20 has a solid cooking surface, upper heating element, lower heating element, fan, and a control unit. The “solid” cooking surface may include a surface that has a substantially non-apertured surface, a hollow portion with a substantially planar surface, a partially apertured surface, or other suitable surface. In a preferred implementation, the solid cooking surface includes a smooth, substantially un-apertured surface, such as a baking stone. The oven 20 described in the above patents is capable of cooking a raw pizza with toppings in less than four minutes with a crispy crust and browned cheese. An additional oven 20 may be provided above the first oven, as shown in FIGS. 1 and 3 . It should be understood that other types of ovens may be substituted for the oven 20 described above, such as a conventional oven, microwave oven, conveyor oven, or other suitable types of ovens.
[0015] The food preparation center 10 provides a station for preparing and cooking custom food products, such as pizza, calzones, stromboli, and other food products, in a timely manner for walk-up or drive-through service. Additionally, the food preparation center 10 may be located in a restaurant, department store, convenience store, outdoor or indoor kiosk, or other suitable location.
[0016] As shown in FIGS. 1 and 3 , the peel storage 22 may be on the side of the food preparation center 10 . A peel 24 may be employed by an operator/cook to provide a movable surface upon which to prepare a pizza or other food item to be cooked in the oven 20 . The peel 24 may also be used to insert and remove the food item into and from, respectively, one of the ovens 20 . The peel 24 may be removed from the peel storage 22 and placed on the food preparation surface 14 . A raw pizza crust or other food item may then be removed from the refrigerated storage 16 in the base unit 12 .
[0017] In the case of a pizza crust, sauce and cheese may already be pre-applied to the crust, or the cheese, sauce, and/or other toppings may be stored in the refrigerated storage unit 16 or in another storage area, such as the topping storage area 18 . The pizza crust may be placed on the peel 24 , on the food preparation surface 14 , or directly in one of the ovens 20 . If additional toppings are desired, toppings may be chosen from the topping storage area 18 and placed on the pizza crust to form a pizza tailored to a customer's order. The peel 24 may then used to place the raw pizza into one of the ovens 20 .
[0018] A cooking code may be entered into a control unit 40 on the front of an oven 20 into which the raw pizza is placed. Various codes may be used for different types of foodstuffs. The cooking codes may correspond to the relative amount of cooking applied to pizzas and/or other types of food items, such as sandwiches, calzones, and other types of foods. The cooking codes may also determine the ratio of heat between multiple cooking elements in the convection oven(s) as well as the amount of convection applied within the oven while cooking a food item. The cooking codes, which may be entered into the control unit 40 by a user, may be a programmed cooking sequence resident in the control unit 40 , and correspond to cooking programs that allow pizzas to be fully cooked in less than four minutes, or allow rapid cooking of other types of raw foodstuffs. In most cases the pizza will be completely assembled and cooked in less than four minutes as the oven may require as little as two and a half minutes to cook a raw pizza.
[0019] Shelves 28 may be provided for storage of non-refrigerated items, such as pizza boxes or spices. Alternatively, additional ovens 20 may be added above or below the ovens 20 shown in FIGS. 1 and 3 . Additional ovens may also be attached to either side of the food preparation center 10 to increase the cooking capacity.
[0020] FIG. 4 shows an alternative configuration for a food preparation center 10 . The food preparation center 10 ′ includes many similar features as the food preparation center 10 depicted in FIGS. 1-3 . The food preparation center 10 ′ includes ovens 20 in a side-by-side configuration. Such a configuration may allow for a larger food preparation surface 14 . Additionally, four or more ovens 20 (not shown) may be placed in a food preparation center 10 ′ such that the ovens 20 are stacked both vertically and horizontally in the food preparation center 10 ′. The food preparation center 10 ′ may include two topping storage areas 18 , each having a topping storage area cover 19 . Alternatively, the food preparation center 10 ′ may include only one topping storage area 18 such that the food preparation surface 14 is larger. Such a configuration may be advantageous if the food preparation center is manufactured as a cabinet-depth system which affords a smaller depth from the front of the preparation center to the rear of the preparation center.
[0021] Similar to the food preparation center 10 illustrated in FIGS. 1-3 , the food preparation center 10 ′ includes at least one base unit 12 with a food preparation surface 14 and a refrigerated storage 16 . Also, the topping storage area(s) 18 may be recessed into the food preparation surface 14 . One or more of the topping storage areas 18 may also be refrigerated, non-refrigerated, and/or covered by a topping storage cover 19 . An oven 20 is positioned on top of the base unit 12 . Peel storage 22 is attached to the side of base unit 12 , and peels 24 are stored in peel storage 22 . In certain implementations, the doors and covers, such as the doors for the ovens 20 , the refrigerated storage 16 , and or the covers for the topping storage areas 18 may be manufactured out of suitable materials, such as metals, plastics, wood, glass, or any combination of thereof. It may be desirable, in various implementations, to have glass, plastic, composite, or other suitable transparent or semi-transparent materials incorporated into barriers of the food preparation centers 10 and/or 10 ′ such as the doors and lids. Such transparent or semi-transparent materials may allow viewing of the contents behind the barriers, such as a cooking pizza or the contents of a refrigerated area(s) of the food preparation center.
[0022] As illustrated in FIGS. 1 and 3 , wheels 42 may be attached to the bottom of the food preparation center 10 to facilitate movement of the food preparation center 10 from one location to another. In various implementations, the food preparation center 10 may be used by street vendors, concessionaires, or other food providers that require the transportation of the food preparation center 10 . Accordingly, the wheels 42 may allow a user to load or unload the food preparation center 10 onto trucks, planes, or other suitable vessels. The wheels 42 may be traditional wheels, castors, rollers, or other suitable apparatus for facilitating the rolling of the food preparation center 10 from one location to another.
[0023] As best illustrated in FIGS. 1-3 , a shelf or shelves 28 may be attached via shelf supports 44 . In the implementation shown, the shelf supports 44 are shown as posts. In addition to posts, cylinders, a welded post, or blocks may be used as shelf supports 44 . The shelf supports may be securely attached to the underside or “bottom” of the shelf 28 by inserting the shelf supports 44 into indentations located on the bottom of the shelf 28 . Alternatively, the shelf supports 44 may be permanently or semi-permanently attached to the bottom of the shelf 28 . Permanent or semi-permanent attachment of the shelf supports 44 to the shelf 28 may be accomplished by welding, gluing, bolting, riveting, or other suitable method of attachment.
[0024] The shelf supports 44 may also be insertable into indentations 46 on the top of the food preparation center 10 . The indentations 46 may be a pre-sized indentation corresponding to the diameter or shape of a shelf support 44 , or may be a general indentation that resists, but does not prevent, the removal of the shelf supports 44 when a force is applied thereto. Although the Figures illustrate the indentations 46 on the top surface of the oven 20 (which may be a heat shield), other implementations may include indentions or receivers at other suitable locations. For example, the indentations may be on the top surface of a permanently attached shelf 28 , on the food preparation surface 14 , or other suitable location. Additionally, the shelf supports 44 may be any suitable length for attaching a shelf to the food preparation center at a desired height.
[0025] A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, conveyor ovens, conventional ovens, microwave ovens, toaster ovens, or other types of ovens may be substituted for the convection oven 20 . Accordingly, other embodiments are within the scope of the following claims.
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A compact scalable food preparation center ( 10 ) is adapted for the preparation of custom ordered pizzas on a walk-in or drive-through basis. The center has a base unit ( 12 ) with a food preparation surface ( 14 ), a refrigerated storage unit ( 16 ) under the food preparation surface, and a refrigerated topping storage area ( 18 ) on the food preparation surface, the topping storage area having a cover ( 19 ). An oven ( 20 ) is positioned on top of the base unit with a solid cooking surface and heating elements spaced above the solid cooking surface. The oven is controlled to cook non-frozen raw pizzas with toppings in less than 4 minutes.
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TECHNICAL FIELD
[0001] This invention relates to a selectorized dumbbell having a handle which carries an adjustable number of weights depending upon the position of a manually movable selector. More particularly, this invention relates to a method of manufacturing the weights for such a selectorized dumbbell and to the weights produced by such manufacturing method.
BACKGROUND OF THE INVENTION
[0002] The PowerBlock® is a well known selectorized dumbbell manufactured and sold by Intellbell, Inc. of Owatonna, Minn. In such a dumbbell, a plurality of weights are provided that form a set of nested left weight plates and a set of nested right weight plates. The two sets of nested weight plates are laterally separated from one another by a space or gap. A handle can be inserted or dropped down into the gap to allow the handle to pick up a desired number of weight plates from each stack. The amount of the exercise mass provided by the selectorized dumbbell depends upon how many weight plates from each stack are coupled to each end of the handle.
[0003] In the PowerBlock® selectorized dumbbell, each weight comprises a left weight plate that is integrally joined to a corresponding right weight plate by a pair of side rails. The side rails are welded at each end to one side of each weight plate. One side rail is welded to the front sides of the left and right weight plates. The other side rail is welded to the rear side of the left and right side plates.
[0004] FIG. 3 of this application shows a single weight from the PowerBlock® selectorized dumbbell. The weight is formed by a joined pair of weight plates with only the front side rail being shown in FIG. 3 , the rear side rail being hidden on the other side of the weight plates in FIG. 3 . The weight plates in different weights are spaced further apart and the side rails used to join these weight plates together are correspondingly longer and vertically offset. This permits the nesting of the weight plates together in their respective left and right stacks of weight plates.
[0005] The selector in the PowerBlock® selectorized dumbbell comprises a pin that may be selectively positioned beneath the side rails of any desired weight. Thus, when the selector is so positioned and the handle is lifted, the handle will carry with it the weight selected by the position of the pin along with all weights above the selected weight. The amount of the weight carried by the handle is adjusted by vertically repositioning the pin so as to insert the pin beneath a higher or lower side rail.
[0006] In the past, certain models of PowerBlock® selectorized dumbbells have used ½″ stamped steel plates as the weight plates in manufacturing the individual weights. Such ½″ weight plates typically have significant manufacturing imperfections along the edges thereof. These imperfections include burrs, rough spots, and the like, formed by the edges of the stamping die when the weight plates are stamped out of ½″ steel stock. Thus, it was necessary to use a CNC milling machine to mill the edges of such ½″ weight plates to remove such imperfections and in doing so the ½″ weight plates were provided with curved edges along all four sides thereof.
[0007] FIG. 5 shows in phantom the roughly rectangular edges of the ½″ weight plate as it came out of the die and in solid the curved edge formed by the milling step. Obviously, the material between the curved edge and the phantom line rectangular edge represents the material removed during the milling step. In addition, each ½″ weight plate also had a pair of mounting holes stamped through each plate in order to secure the plate to the milling machine used in the milling operation. Such holes also represent a significant loss of material from each ½″ weight plate.
[0008] After the edges of the ½″ weight plates were milled as described above, two such plates were then inserted into a welding fixture at whatever spacing was appropriate to the weight being manufactured. The two side rails for this weight were then welded to the weight plates at generally identical heights along the front and rear sides of the weight plates to join the weight plates together. The weight plates and side rails were then cleaned of debris and contaminants by spraying them with a cleaner. Finally, the weight formed by the weight plates and the side rails went through a powder coating process to apply a finish coating to the side rails and to both sides of the weight plates.
[0009] While this is an effective way to manufacture weights for selectorized dumbbells, it does involve labor in terms of milling the edges of the weight plates to make them sufficiently smooth to be acceptable. In addition, given recent price increases for ½″ steel stock, the prices for obtaining ½″ stamped steel plates has dramatically increased. This forces the manufacturer of selectorized dumbbells to either increase prices, which is not favored by the purchasers of such dumbbells, or to make less margin on the product, which is not favored by the manufacturer. A simpler and less expensive way to manufacture selectorized dumbbell weights would be an advance in the art.
SUMMARY OF THE INVENTION
[0010] One aspect of this invention relates to a selectorized dumbbell having a handle. A plurality of weights are nested together forming a nested first stack of weight plates and a nested second stack of weight plates. The first and second stacks of weight plates are separated by a gap that is large enough to accommodate at least a portion of the handle therebetween. A selector is movable by a user to allow a desired number of weight plates from each of the first and second stacks to be coupled to either end of the handle when the handle portion is located in the gap between the first and second stacks and the selector is manipulated by the user. The weight plates comprise full thickness weight plates. Each full thickness weight plate comprises a plurality of partial thickness stamped steel weight subplates that are abutted with one another and welded to one another to form the full thickness weight plate.
[0011] Another aspect of this invention relates to a method of manufacturing a weight for use in a selectorized dumbbell. The selectorized dumbbell has a plurality of nested weights disposed in a stack of nested left weight plates and nested right weight plates, the weight plates each having a predetermined full thickness. The method comprises providing a plurality of stamped steel weight subplates having a partial thickness compared to the full thickness of the weight plate, abutting at least a pair of the weight subplates against one another in a face-to-face manner to form each weight plate in the weight; and welding the weight subplates together.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] This invention will be described more completely in the following Detailed Description, when taken in conjunction with the following drawings, in which like reference numerals refer to like elements throughout.
[0013] FIG. 1 is a perspective view of a selectorized dumbbell according to this invention, particularly illustrating the nested weights of the dumbbell with each weight having a ½″ weight plate at each end, the ½″ weight plate being formed from a pair of joined ¼″ weight subplates;
[0014] FIG. 2 is a side elevational view of a selectorized dumbbell weight according to this invention;
[0015] FIG. 3 is a side elevational view similar to FIG. 2 , but showing a prior art selectorized dumbbell weight;
[0016] FIG. 4 is an enlarged side elevational view of the edges of the selectorized dumbbell weight of FIG. 2 ;
[0017] FIG. 5 is an enlarged side elevational view similar to FIG. 4 of the edges of the prior art selectorized dumbbell weight of FIG. 3 , particularly illustrating the edges in phantom as they appear coming from the stamping die and in solid after being milled by a milling tool;
[0018] FIG. 6 is an end elevational view of the selectorized dumbbell weight of FIG. 2 ; and
[0019] FIG. 7 is a cross-sectional view taken along lines 7 - 7 in FIG. 6 of the selectorized dumbbell weight of FIG. 2 .
DETAILED DESCRIPTION
[0020] Referring first to FIG. 1 , a first embodiment of a selectorized dumbbell is illustrated generally as 2 . Dumbbell 2 as shown herein is similar to an existing product known as the PowerBlock® which is manufactured and sold by Intellbell, Inc. of Owatonna, Minn., and which is shown in the Applicants' U.S. Pat. No. 5,779,604, which is hereby incorporated by reference. A summary description of dumbbell 2 will be provided herein only as needed to understand this invention. Reference may be had to U.S. Pat. No. 5,779,604 for a fuller and more complete description of dumbbell 2 .
[0021] Basically, dumbbell 2 includes a handle 4 and a plurality of nested weights 6 which can be selectively coupled to handle 4 using a selector 8 , namely a pin that can be moved between different positions on handle 4 . Each weight includes a pair of ½″ weight plates 10 that are joined along each side by a side rail 12 . Side rail 12 has one end joined to one weight plate 10 in each pair and the other end joined to the other weight plate 10 in each pair.
[0022] Side rails 12 hold weight plates 10 apart by a predetermined distance corresponding to the length of side rails 12 . Different weights 6 have different length side rails 12 so that weight plates 10 in different weights 6 are spaced apart by different distances. Side rails 12 of different weights 6 are joined to weight plates 10 at different vertical heights, with the heights of side rails 12 decreasing as the distance between weight plates 10 increases. See FIG. 1 . Thus, weights 6 can be nested together with weight plates 10 on one side forming a first or left stack of nested weight plates and weight plates 10 on the other side forming a second or right stack of nested weight plates.
[0023] A desired number of weights 6 can be selectively coupled to handle 4 depending upon how selector 8 is positioned. If selector 8 is inserted into handle 4 beneath the lowermost side rails 12 , then selector 8 will pick up all weights 6 when handle 4 is lifted. Moving the selector 8 up will pick up fewer weights to thereby adjust the exercise mass carried by handle 4 . Essentially, only those weights 6 whose side rails 12 are above the location of selector 8 will be coupled to handle 4 .
[0024] This invention is based upon forming each ½″ weight plate 10 from a pair of ¼″ weight subplates 14 that are joined together in the manner to be described hereafter. Doing so provides a weight 6 for dumbbell 2 that is dramatically less expensive to manufacture. This provides a competitive advantage to a manufacturer that uses such a weight 6 .
[0025] The term “subplate” to describe the ¼″ weight subplates 14 has been adopted only as a device to distinguish the ¼″ weight subplates from the ½″ weight plate 10 formed thereby. It does not mean that the ¼″ weight subplates 14 are not “plates” in the normal sense of the word, but only that multiple thinner subplates are used to form what is going to be referred to herein as a plate.
[0026] One might logically expect that a ¼″ steel subplate would cost approximately one half of the cost of a ½″ steel plate of the same size. Thus, if a ½″ steel plate were to cost $1.00, one would expect a ¼″ steel subplate to cost $0.50. However, the Applicants realized this is not typically the case and that a ½″ steel subplate in the above example costs less than $0.50. The Applicants discovered that this is due to the faster tool cycle time used in stamping out ¼″ steel subplates along with the fact that there is less waste or selvage in the steel sheet when stamping out ¼″ steel subplates as compared to ½″ steel plates. Thus, a fact first appreciated by the Applicants is that ¼″ steel subplates cost disproportionately less than ½″ steel plates. One can buy two ¼″ steel subplates for less than one ½″ steel plate of the same size.
[0027] Moreover, the Applicants also realized that ¼″ steel subplates can be stamped out of ¼″ hot rolled steel bar stock with adequate precision. Cold rolled steel bar stock must be used when stamping out ½″ weight plates since the bar stock must have greater dimensional consistency than when stamping from ¼″ steel bar stock. For any given thickness of steel, hot rolled steel is much less expensive than cold rolled steel. Thus, an additional increment of savings is achieved because the ¼″ steel subplates are desirably stamped out of hot rolled steel.
[0028] In addition, the Applicants also learned that one can control the stamping process to turn out ¼″ steel subplates that are substantially free of edge imperfections or have such minor edge imperfections that a subsequent powder coating or painting process will substantially hide and cover such imperfections. A template (not shown) is provided to the stamping operator. This template is in the shape of the desired subplate that is to be stamped but is very slightly larger than that shape. This template is to be used in setting up the stamping operation.
[0029] More particularly, the stamping operator can run a few test shots in which a few ¼″ steel subplates are stamped out. The stamping operator can then adjust the pressure used in the stamping operation and the cycle time to adjust for the hardness and other characteristics of the steel in the bar stock being used in the stamping operation until plates are stamped out that fit within the subplate template. In other words, adjustments are made by the stamping operator until the stamping tool is stamping out ¼″ steel subplates that have such little edge imperfections that the subplates will fit within the subplate template. Then, an entire manufacturing run can be done to turn out hundreds or thousands of such subplates with substantially no waste. Substantially all of the subplates will fit within the template.
[0030] The result of this is that ¼″ stamped steel subplates 14 can be used as weight subplates to form a larger ½″ weight plate 10 without having to mill the edges to remove edge imperfections. Such weight subplates 14 can be used by the manufacturer of the exercise equipment directly as they come from the stamper as long as the stamper has taken care to ensure that the stamping operation is adjusted until the ¼″ weight subplates fit within the subplate template. This provides another substantial savings to the manufacturer of the dumbbell. The dumbbell manufacturer no longer has to spend time or labor in milling weight plates 10 prior to their assembly in the selectorized dumbbell weight 6 .
[0031] In manufacturing a selectorized dumbbell weight 6 according to this invention, a pair of the ¼″ weight subplates 14 are sandwiched against one another to form a single ½″ weight plate 10 . However, before this is done, the Applicants further discovered that it is important to remove any residue of the lubricating oil that was used in the stamping process from both faces of ¼″ weight subplates 14 . If such lubricating oil is left on ¼″ weight subplates 14 , the oil on the faces that abut or contact with one another will then be trapped and cannot be removed in any subsequent cleaning step prior to powder coating. Then, when ¼″ weight subplates 14 are eventually powder coated, the trapped oil will mar the coating process and cause the powder coating to undesirably bubble along the meeting line between the paired ¼″ weight subplates 14 .
[0032] Accordingly, ¼″ weight subplates 14 desirably have any lubricating oil residue sufficiently removed therefrom such that the joined pair of ¼″ weight subplates can subsequently be powder coated without bubbling or marring the powder coating. This oil residue removal can be accomplished in different ways. One way would be to clean or spray ¼″ weight subplates 14 after they are stamped but before they are assembled together in pairs using a suitable cleaning solvent. Alternatively and preferably, the stamping operator can use an evaporating oil as the lubricant in the stamping process. Then, after ¼″ weight subplates 14 are stamped out, the oil simply evaporates leaving a weight subplate 14 sufficiently clean of oil residue so that the subsequently applied powder coating will not bubble.
[0033] In any event, a pair of stamped ¼″ weight subplates 14 which are sufficiently free of oil residue will be used to form each ½″ left and right weight plate 10 of the selectorized dumbbell weight 6 . The Applicants also realized that such stamped ¼″ weight subplates 14 will be curved as a result of the stamping process and as a result of using hot rolled steel in the stamping process. One face 16 of weight subplate 14 is slightly concave and the other face 18 of weight subplate 14 is slightly convex. The amount of the curve in the concave and convex faces 16 and 18 is sufficiently small as to be imperceptible to the eye (the curve has been exaggerated in FIG. 7 for clarity). Thus, some type of indicia or mark 20 , such as the words MADE IN USA, is stamped on the same face of each weight subplate 14 , i.e. on convex face 18 .
[0034] When the pair of stamped ¼″ weight subplates 14 are placed into the welding fixture by an operator, the operator takes care so that the curvature indicia 20 on each subplate 14 is always in the same place facing towards the outside of the fixture. In other words, convex face 18 of each weight subplate 14 is to the outside of the fixture and concave face 16 is to the inside of the fixture. Thus, the two weight subplates 13 will smoothly mate with one another with convex outer face 18 of the innermost weight subplate 14 nested against the concave inner face 16 of the outermost weight subplate 14 . See FIG. 7 . This prevents tolerance problems from compounding themselves along the entire length of the nested weights 6 .
[0035] After the stamped ¼″ weight subplates are properly aligned and nested with each other and are in the welding fixture, side rails 12 can then be placed into the welding fixture. Each end of side rail 12 is positioned overlying the junction or interface between the pair of ¼″ weight subplates 14 along one side of weight subplates 14 . Again, see FIG. 7 . The ends of side rails 12 can then be welded simultaneously to both of weight subplates 14 with the completed weld 22 bridging the interface between weight subplates 14 as well as joining weight subplates 14 to side rail 12 . Such a weld 22 will adequately hold side rails 12 to weight subplates 14 as well as weight subplates 14 to each other.
[0036] After the welding step set forth above, weights 6 are finished in a conventional powder coating step. The welded weights 6 , each comprising a ½″ weight plate 10 formed by a pair of ¼″ weight subplates 14 at each end of side rails 12 , will then simply be powder coated to apply a finish coating over the entire surface of weights 6 . This powder coating will substantially cover any edge imperfections that might have existed when ¼″ weight subplates 14 were stamped.
[0037] The end result of this manufacturing method is a novel selectorized dumbbell weight 6 that is much less expensive to manufacture. Thus, a manufacturer can afford to keep selling selectorized dumbbells 2 having such weights 6 without substantially increasing the retail price of such dumbbells 2 even when the price of stamped steel plates is high. Alternatively, the profit margin made by the manufacturer can be maintained or increased.
[0038] In addition, much less material is lost when using two ¼″ weight subplates rather than a single ½″ weight plate. No milling is needed. Thus, none of the material of the ¼″ weight subplate is lost by having to be stamped out to form mounting holes for the milling operation or by being milled away. Thus, for the same amount of steel used at the beginning of the manufacturing process, a complete selectorized dumbbell 2 manufactured according to this invention will be five pounds heavier (i.e. 90 pounds) than the corresponding selectorized dumbbell manufactured with ½″ weight plates (i.e. 85 pounds). Thus, more value is delivered to the end user.
[0039] Various modifications of this invention will be apparent to those skilled in the art. Accordingly, the scope of this invention will be limited only by the appended claims.
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This invention relates to a selectorized dumbbell having a handle that can be dropped down between nested left and right stacks of weight plates. The weight plates can comprise individual weights or a pair of weight plates, one from each stack, can be connected together to form a single weight. A selector is provided to allow the user to select a desired number of weight plates from each stack and couple such weight plates to the handle to provide an adjustable weight dumbbell. Each weight plate comprises a pair of thinner or partial thickness weight subplates that are abutted and welded together, e.g. a ½″ weight plate is formed by a pair of ¼″ weight subplates. This substantially decreases the cost of manufacturing the selectorized dumbbell.
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[0001] This application is a continuation of PCT/US06/31369 filed on Aug. 11, 2006 and is a continuation in part of PCT/US06/06662 filed on Feb. 24, 2006 which claimed priority to U.S. provisional application No. 60/657,512, filed on Feb. 28, 2005. This application claims the priority benefit of these applications, and which are incorporated by reference herein in their entirety.
TECHNICAL FIELD
[0002] This invention relates to large lifting bags for lifting and transporting hazardous or radioactive materials.
BACKGROUND ART
[0003] Transportation of bulk materials in the United States is regulated by the United States Department of Transportation, particularly for transportation of hazardous or radioactive materials. See 49 CFR pt. 173 (incorporated by reference). In particular, containers for transportation of hazardous and radioactive materials are required to meet certain design safety criteria. See generally, 49 CFR 173 subpart I. Certain packaging design guidelines for Industrial Packaging, Types 1, 2, or 3, or Type A package (see 40 CFR 173.403) are specified in 49 CFR 410-411. Transportation of bulk materials is similarly regulated in Europe and elsewhere. Bags designed to large scale storage and transportation are typically adapted to carry loads in excess of 10000 pounds.
[0004] The United States guidelines specify testing requirements that packaging must undergo to be certified as meeting the guidelines. See 49 CFR 173.465. Included in the testing procedures are a free drop test, and a stacking test. The free drop test requires a package to be loaded or filled to its design weight capacity and dropped from a specific height (1-4 feet, depending on design weight) and to maintain structural integrity after impact. The stack test requires a loaded package to be subject to a compressive load of five times the actual capacity weight of the package. Such testing requirements place substantial restrictions on possible construction of the packaging. For packaging that comprises a flexible bag capable of being lifted when loaded, the drop test and stack test present heavy design hurdles. One possible flexible bag design is shown in U.S. Pat. No. 6,142,727 (the '727 patent), attached hereto and made a part hereof, in its entirety.
[0005] The lifting bag in the '727 patent has several drawbacks. First, the lifting straps are attached to the outer cover of the bag, which places stress on the outer cover during lifting operations. Second, the lifting straps encircle the bottom of the bag in an even rectangular grid, which results in an even distribution of weight during lifting provided the lifting forces are evenly distributed. If the lifting forces are not evenly distributed, the bag is subject to torsional forces and the rectangular webbing support grid on the bottom of the bag will not sufficiently compensate for these twisting forces, resulting in bag deformation and unnecessary stress, particularly on the bag seams. Further, an uneven load distribution within the bag can result in torsional forces despite the application of evenly applied lifting forces. Finally, the bag employs a complex flap folding procedure to seal the bag, which is cumbersome and time consuming.
[0006] Another lifting bag design is that disclosed in PCT/US06/06662 (the '662 application, hereby incorporated by reference in its entirety). This design uses a bottom support and side support lifting apparatus, where the support members are generally webbing or ropes, and is attached to the bag at designated locations, either on the bottom or the sides, but not the bag top portion. The bag can be constructed from a series of panels. While the bag design is less complicated that that of the '727 patent, construction can be arduous and time consuming.
SUMMARY OF THE INVENTION
[0007] A lifting bag including a lifting strap system designed to carry substantial loads. The lifting strap system may be detached from the bag but coupled to the bag, particularly, detached near the bag top portion. The lifting system can be one piece or a two piece unit. The lifting bag has a edge strip attached to or near the top edge to allow for placement of the lifting strap system. One of the bags that can be used has a top center zipper, and can be constructed from a single sheet of fabric. To open the bag, the zipper is unzipped and the top portion of the bag is inverted and placed over the frame or container.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of one embodiment of a lifting bag.
[0009] FIG. 2A is a plan view of the single sheet construction.
[0010] FIG. 2B is a plan view of the folded sheet of FIG. 2A .
[0011] FIG. 2C is a perspective view of the cylinder formed by joining the sides of the sheet in FIG. 2B
[0012] FIG. 2D is a perspective view of the cylinder in FIG. 2C which a bottom seam
[0013] FIG. 3A is a perspective view of the bag of FIG. 2D with a flattened bottom.
[0014] FIG. 3B is a top view of the bag of FIG. 3A .
[0015] FIG. 3C is a perspective view of the bag of FIG. 3 a with the triangular folds removed.
[0016] FIG. 3D is a top view of the bag in FIG. 3C .
[0017] FIG. 4A is a plan view of the single piece construction removing fabric before assembly.
[0018] FIG. 4B is a plan view of a two piece construction embodiment having a separate bottom.
[0019] FIG. 4C is a plan view of a two piece construction using two overlapping panels.
[0020] FIG. 5 a perspective view of the completed bag of FIG. 3 with the top zippered closed.
[0021] FIG. 6A is a perspective view of the competed bag of FIG. 5 placed in a container with the top zippered closed.
[0022] FIG. 6B is a perspective view of the completed bag of FIG. 5 in a container with the top open and inverted.
[0023] FIG. 7 is a perspective view of a two layer single piece construction having two closable tops.
[0024] FIG. 8 is a perspective view of one embodiment of a lifting strap system.
[0025] FIG. 9 is a perspective view of the lifting strap system of FIG. 8 with an encompassing belly strap.
[0026] FIG. 10 A is a side view of one embodiment of an edge strip
[0027] FIG. 10 B is a top view of another embodiment of an edge strip
[0028] FIG. 10C is a side view of another embodiment of an edge strip.
[0029] FIG. 11 is a perspective view of a completed lifting bag with lifting strap system and a raincap.
[0030] FIG. 12A is a plan view of the single piece double layered fabric composed showing an inner zipper and outer zipper. The view is an interior facing view.
[0031] FIG. 12B is a top view showing of a double zippered bag showing the relationship of the zippers.
DETAILED DESCRIPTION OF THE INVENTION
[0032] Shown in FIG. 1 is one embodiment of the invention, comprising a lifting bag 1 , constructed to meet IP-2 standards for 24,000 lbs capacity. The bag 1 has two opposing sidewalls 2 , 3 ; two opposing end walls 4 , 5 ; a top portion 10 ; and a bottom 20 . As shown, the lifting bag 1 forms a rectangular shaped enclosure (as shown, about 8′×7′×4.5′ or 8′×5.5′×5.5′), having an interior volume, with an open top defined by the upper ends of the end walls and sidewalls. Other bag shapes and sizes are possible, such as a cubical shape or cylindrical shape. As the bag is not self supporting, a frame must be provided to support the bag during loading. A metal or wooden frame can be used, such as shown in FIGS. 5-7 of U.S. Pat. No. 6,142,727, or a bulk container can be used, and all types of support will be considered as “frames.” The bag is positioned in the interior of the frame, and the top portion of the lifting straps 50 (later described) lie over the outside of the frame. The tops of the lifting straps may be secured to the exterior of the frame if desired. Alternatively, the bag may have support loops attached to the exterior to tie to the frame support frame during filling operations to tie the bag to the support structure.
[0033] The bag sidewalls and bottom are constructed of a robust flexible fabric, such as 6.0-18+ oz coated woven (or non-woven) polypropylene or polyethylene, with coated polypropylene being preferred. The coating, if provided, is usually polyethylene (typically 1-3 mil coating). It is preferred that the top also be made of a robust flexible fabric. For strength, the bottom layer may be a multilayer construction. For one particular embodiment, a lifting bag, having two layers of 6.0 oz coated woven polypropylene, or one layer of 6.0 oz woven polypropylene and a second layer of 8 oz woven polypropylene have been utilized (more preferred). The bag may have a separate liner positioned in the interior of the bag (a bag in a bag) with the liner attached to the top of the bag, and if desired, also attached to the four side corners of the bag.
[0034] Various constructions of the enclosure are possible: the sidewalls and end walls may be constructed from a single piece of fabric; the bottom and sidewalls (or bottom and end walls) may each be constructed from a single sheet of fabric, etc. One embodiment uses separate cut pieces or panels of fabric for each wall, bottom and top, with the panels joined by stitching. Alternatively, two pieces of fabric could be overlaid in an “x” or “t” shape creating a double layer for the bottom of the bag. When separate pieces of fabric are used, the pieces can be joined through stitching. Means other than stitching can be utilized to join wall/bottom/top members, such as plastic welding (heat welding, radio frequency welding, etc), adhesion or a combination of means.
[0035] A preferred means of construction is to build the bag from a single fabric sheet 1005 or a single multilayer fabric sheet. The multiple sheets can be coextensive when laid on top of one another, or the innermost fabric can be shorter in height that the outermost fabric if it is not desired to have the top of the resulting bag lined. An additional horizontal layer positioned near the bottom edge can be used to form a reinforced bottom. Other multilayered designs are possible by modifying the laminated structure of a multilayer sheet. For ease of explanation, construction will be described using a single sized multilayer fabric piece, with two side edges 1001 A and 1001 B, a bottom edge 1001 C, and a top edge 1001 D, as shown in FIG. 2 .
[0036] Using a single fabric piece constructed as described, the resulting assembled bag will have a center opening on the bag top, preferably closable with a zipper 1070 , such as shown in FIG. 1 . To construct the bag with a zippered opening, one side of a zipper chain 1005 is attached one of the long edges of the fabric, shown in FIG. 2A , at the top edge. Generally, a sewn attachment is preferred forming a seam. It is preferred that the edges of the fabric on the seam be folded over about 0.5-2 inches to create extra strength at the seam. This overlap is desired for all seams on the bag.
[0037] Also attached lengthwise and parallel to the half zipper chain is a edge strip 1006 . In the present embodiment, this strip is positioned so that when the bag is complete, the edge strip 1006 is positioned at or near the top edge of the completed bag. As shown the strip is a single strip of fabric, here a strip of 2″ wide polyester webbing. The edge strip may be several discontinuous strips place only where needed to couple to the lifting straps in the lifting strap system, as later described. Other positions of the edge strip on the bag sides may be desired or additional edge strips may be included on the bag sides as needed (e.g. a strip positioned near the bag sidewall center or bag sidewall bottom edge). The edge strip 1006 is preferred but can be eliminated depending upon the type of lifting system used to lift a loaded bag, as later described. If the edge strip is not used, it is still desired, in a multilayered fabric embodiment, to place a stitch along a horizontal line at or near the location that will become the top edge of the completed bag. Such a stitch or join will keep the inner liner material from separating or sagging away from the outer material.
[0038] For instance, to form an 8′4″×8′10′ bag, a single or multilayer fabric piece of 12×14′6′ fabric is used. To construct the bag, the single piece of bag fabric 1001 has the two ends 1001 A and 1001 B joined together, creating an opened top and bottom oblong cylinder FIG. 2C . The bottom edge of the cylinder 1001 C (the edge opposite that having the zipper edge) is closed by attaching (preferably a sewn attachment) the opposing sides of the bottom edge of the cylinder (e.g. flatten the cylinder, creating two opposed sides, and attach the opposed sides). See FIG. 2D . The resulting structure resembles an open end toothpaste tube, with a seam 1008 running across the tube's bottom 1 , and up one side 1007 . It is preferred that the tube like structure be created in a single step: the fabric piece 1001 is folded to align edges 1001 A and 1001 B, and a join (such as by sewing) edges 1001 A and 100 B together, and the opposing sides of the folded bottom edge 1001 C joined together, creating a bottom seam 1008 and single side seam 1007 (see FIG. 2B ).
[0039] To create a rectangular shaped boxlike structure from this closed bottom cylinder the closed end of the tube structure is flattened inwardly, with excess bottom fabric forming two triangular shaped flaps 1010 A and 1010 B that extend outwardly from the tube bottom (see FIGS. 3A and 3B ). It is preferred that the triangular folds 1010 A and 1010 B be formed so that the bottom seam or join 1008 forms the perpendicular bisector of the triangular flaps 1010 A and B (see FIG. 3B ). Each triangular flap 1010 A and 1010 B is cut or sheared off and the cut edges joined (preferably by sewing) creating two bottom edge seams, 1011 A and 1011 B. The resulting structure now approximates a rectangular shaped open top box structure, having two long sidewalls 1020 , two shorter end walls 1030 and a bottom 1040 . See FIG. 3C . As seen in FIG. 3D , the bottom of the structure has a seam running down the center of the bottom 1008 and along the two edges of the bottom 1031 adjacent the end walls. In the preferred embodiment, one of the end walls 1030 has a seam 1007 running from the top to the bottom edge. See FIG. 3C . The fabric 1050 that will form these triangular folds can be removed or excised from the single fabric piece prior to assembly (such as shown in FIG. 4A ), but this is not preferred, as it makes seam alignment during construction more critical for quality control. Alternatively, instead of removing these triangular folds, the triangular folds could be folded up and attached to the end walls or folded down and attached to the bottom of the bag. In this fashion, an open top boxlike structure is constructed from a single fabric piece.
[0040] Alternatively, this same structure may be formed from two fabric pieced, the fist fabric piece forming the sidewalls of the structure having the ½ zipper chain 1005 attached and edge strip 1006 attached. A separate bottom is then sewn in, such as shown in FIG. 4 b . Alternatively, two intersecting pieces of fabric can be used having sections of edge strip 1006 and ½ zipper chain attached ( FIG. 4B ).
[0041] The next step is to form the top of the bag. Along the open top edge 1001 D of the boxlike structure 1060 is the single side of a zipper chain 1005 . The opposing sides of the open top are now operationally joined into a closable opening by attaching a zipper slide to the two half zipper chains, creating a functional zipper 1070 . Two sipper slides may be added if desired. Zipper stops at added at the two opposing terminal ends of the zipper to maintain the zipper slide on the resulting zipper 1070 . A zipper stop may simply be sewing the two ½ chains together, or otherwise fixing the two ½ chains together to keep the slide from sliding off the terminal ends, or can be a metal or plastic lug positioned at the end of each ½ chain to prevent the slide form exiting off the ½ chain. A #10 nylon coil zipper has been employed. The zippered top, when closed, again creates a toothpaste tube-like top end. The top end is pushed inwardly, again creating two triangular folds 1060 A and 1060 B on the top 1080 of the box shaped bag with the zipper bisecting the two triangular folds. See FIG. 5 . As shown in FIG. 5 , boxlike bag structure now has the edge strip 1006 positioned adjacent or near the top periphery of the edge forming the top portion 1080 of the bag.
[0042] These top triangular flaps 1060 A ands 1060 B are designed to allow the top, when unzipped along the centerline, to be inverted “inside out” thereby allowing the top portion 1080 to be folded over the edges of the container or frame that the bag is placed in, thereby exposing the interior of the bag. The exposed opening is substantially aligned with the open top of the container or frame, allowing loading anywhere along the periphery of the container or frame. See FIGS. 6 A and B showing a container with bag placed inside. As described, the top opening of the bag has a zipper to closure device, but other closure means could be used, such as straps, ties, loops, Velcro, etc. As described, the bag is rectangular shaped, but the bag can be a square boxlike structure, or adapted to fix almost any container shape as the bag is manufactured from flexible fabric. For instance, for a cylindrical shaped container, the general design described above will work, but the bottom end may not be modified beyond creation of the toothpaste tube type bottom.
[0043] When used for construction debris, the bag may include an inner liner 30 , lining all or part of the interior. One liner 30 is constructed from 6 to 12 oz non-woven polypropylene fabric (12 oz being most preferred with a 24,000 lb capacity bag). Alternatively, a liner can be constructed in multiple layers of differing fabrics or materials for strength, puncture resistance or other desired physical properties. It may be desired to reinforce the bag bottom against tearing, in which event a bottom panel can be glued or otherwise directly attached to the exterior bag bottom as a reinforcing patch, or an extra layer of fabric sized to accommodate the resulting bottom can be sewn on the one-piece sheet design in the appropriate location. Inner liner may have a separate zipper attached distinct from the topmost zipper.
[0044] When two zippers are used, the liner and exterior fabric can be attached at the zippers, at the edge strip 1006 , or between the edge strip and the zippers, or a combination. If only joined or attached at the edge strip, the liner and exterior fabric remain as separate flaps above the edge strip. Each can have a half zipper chain 1005 A and 1005 B attached, as shown in FIG. 7A . The liner may be cut slightly shorter (2-4 inches) then the topmost fabric (the “topmost” fabric is that fabric that will form the exterior facing fabric), making it easier for the liner and outer fabric to be zippered shut separately. If it is desired that the inner and outer fabric be joined along the top edge, the two can be seamed together above the edge strip. Alternatively, both inner and outer lining can be joined together when the ½ chain zipper is added if the inner liner is cut shorter (1-2 inches) or the inner zipper ½ chain 2050 is attached about 1-2 inches below the top edge (see FIGS. 12 A and B). The separation of the inner ½ chain zipper 2050 from the outer ½ chain zipper 2060 provides enough freedom between the two zippers on the assembled bag to allow closure of the inner then closure of the outer completed zipper.
[0045] This sheet constructed bag can be used with any lifting strap system know in the art, including a system of intersecting webbing straps are attached to the bag sidewalls, end walls or the bottom of the bag. For instance, the above describe one piece bag can be used with the lifting strap system described in the '727 patent. In this instance, the 5 strap 3 strap pattern intersect at right angles on the bag bottom and the straps are continuously attached on the bottom and walls of the bag, and extend above the bag for lifting. Alternatively, and more preferred, the lifting straps or webbing can be attached to the bag but left “detached” from the bag near the half portion of the bag, to prevent undue stress on the exterior surface of the bag during lifting operations. IAs described in the '662 application, retention loops can be used to position the lifting straps on the exterior surface of the bag, as shown in FIGS. 1-3 of the '662 application.
[0046] Additionally, the one piece bag can be used with a split lifting strap system having a side lifting portion and a bottom lifting portion as described in the '662 application, where the side or bottom portions can be attached either on the lower sidewalls or the bottom of the bag, or both. Again, it is preferred that the lifting strap system be detached from the exterior surface of the bag near the top portion of the bag. However, attaching the lifting strap system directly to the bag, such as by sewing (as described in the '727 patent) or attaching the lifting strap system straps indirectly through retention loops, requires extensive sewing to join the retention loops and the straps to the bag and is labor intensive.
[0047] A more preferred design is to use a lifting strap system that is everywhere detached from the bag or only indirectly attached to the bag (e.g. coupled to the bag) to support and lift the bag. As used herein, “directly” attached means a sewn or welded attachment (or another means of attachment) where the lifting strap, at the point of attachment, cannot move independently from the bag material. Indirect attachment, or coupling, is a means of positioning the lifting strap on the exterior of the bag but allows for movement of the strap with respect to the exterior bag material at the point of indirect attachment. For instance, using a retention loop to position the lifting strap on the bags, as shown in the '662 application, is indirect attachment or coupling of the lifting straps to the bag.
[0048] A preferred lifting strap system is shown in FIG. 8 . As shown, the system is a first series of parallel straps 2000 , and a second series of parallel straps 2001 , where the first and second series intersect at right angles creating a grid that will be located adjacent the bag bottom. Each strap has two distal ends that terminate in a connector 2010 . As described, the straps are generally a fabric webbing, such as 2-3 inch polyester webbing, but other materials can be used. As generically described, the lifting strap system is composed of support straps, (continuous piece straps or multi piece straps). The connector can be a loop of fabric 2010 (shown in FIG. 8 ) or can be a connector such as a carbineer, snap hook, etc. or a partially or totally encircling perimeter support member (such as a rope). It is preferred that the first and second group of straps be directly joined at one or several point of intersection along the lifting system bottom portion to maintain a integrated structure, but it is not necessary that every intersection be a direct join. As shown in FIG. 8 , the first groups of straps 2000 is a series of four straps, and the second group 2001 is a series of three straps. The actual number of straps in each group can vary with the application. The first group will extend between the long sidewalls and support the bag bottom, while the second group will extend between the shorter length end walls and support the bottom.
[0049] Additional straps can be attached to the lifting strap system and placed at other locations on the lifting system, as desired. One such additional strap is positioned “horizontally” when the strap system is coupled to the bag, joining the first and second groups of straps. As shown in FIG. 9 , this additional strap creates a perimeter encircling “belly strap” 2020 that is located at a height to provide support around the perimeter of the bag about ⅓-½ of the distance from the bag bottom. It has been found that a fully loaded bag naturally forms a teardrop like bulge near the bottom ½ of the bag. The belly strap 2020 provides additional sidewall and end wall support in this case. When using a belly strap 2020 , it is not necessary that the first and second group of straps be directly joined at intersections along the bottom.
[0050] Other lifting strap system designs are possible. When torsional forces are a concern, the bottom portion of the lifting strap system can be constructed to accommodate side-to-side forces, such as the bottom design shown in FIG. 10 or 13 of the '662 application and included herein for reference. Preferred materials for the sling lifting straps are 1.5-3″ wide polyethylene webbing, but other materials can be used where appropriate.
[0051] As described, the lifting strap system (henceforth considered as a number of straps) are joined together at some of all of the strap intersections, generally by sewing. The completed lifting strap system is a one piece unitary structure in the sense that there are enough direct joins of the crossing straps so that if the system is lifted at one strap, all straps will be lifted. The lifting strap system can be composed of two parts, a bottom weave and a side weave that can be joined together, as shown in FIGS. 1, 6 and 10 of the '662 application.
[0052] It is necessary to position the lifting strap system next to the lifting bag for lifting purposes. One means to position the lifting strap system is by using retention loops to couple or indirectly attach the straps to the bag, such as shown in FIG. 2 of the '662 application. These retention loops are short pieces of fabric, such as webbing, that are stitched to the bag at opposing ends of the fabric strip to create a loop much like a belt loop with a center opening through which a lifting strap can be threaded. Retention loops are positioned on the exterior surface of the bag as needed to support and properly position the lifting straps in the sling. However, it is simpler and more efficient to directly attach (sewn is the preferred method) to the bag exterior walls a single edge strip 1006 , as described above. One version of the edge strip 1006 is shown in FIG. 10A . As shown, it is a single 2″ wide webbing (such as polypropylene, polyester, polyethylene) strap with slits 1061 positioned along a line offset from the strap center line. The strap is attached (e.g. sewn) to the bag near the bag top edge, and the slits 1061 in the strap are aligned with the desired side lifting straps of the lifting strap system, allowing the side portions of the lifting strap system to be threaded through the slits 1061 . Instead of a single strap, the edge strip 1006 can be constructed from two straps, one a straight strap 1006 A that will be attached to the bag's side and end walls, and as second strap 1006 B that is attached to the first strap 1006 leaving undulations in the second strap. A top view is of this two strap arrangement is shown in FIG. 10B . Alternatively, the edge strip 1006 may be a singled strap with grommets 1009 instead of slits positioned periodically therethrough ( FIG. 10C ). Individual fabric or webbing strips could be threaded through one or two grommets where needed to form a loop to accommodate one of the lifting straps, or a single fabric strip could be threaded though a series of grommets creating the undulations shown in FIG. 10C . It may be desired to also have another edge strip 1006 positioned around the bag's sidewall bottom perimeter or the edge of the bag adjacent to the bag bottom, to support the lifting straps near or on the bag bottom. Retention loops and the edge strip may be constructed from 1.5-2.5 inch polypropylene or polyester webbing, 1.5-2.5 inch elastic knitted latex webbing, ¾ inch rope, or any suitable material. Strap material can be constructed from 1.5-3 inch polypropylene, polyester or nylon webbing, ¾″ rope (kermantal preferred) or other suitable materials.
[0053] In use, a lifting strap system is coupled to the bag by threading the individual straps (some or all) through the edge strip 1006 , at suitable locations. By threading the lifting straps through the loops created by the edge strip, the lifting straps are positionally fixed horizontally (with some degree of movement) with respect to the bag, but still free to move vertically. It may be desired to removably fix the lifting straps vertically to the edge strip or retention loops. To accomplish this, a fastener is provided to removably bridge vertically around the edge strip. For instance, the area of the side straps near the loop on the edge strip are lined with one side of a hook and loop type fastener, such as Velcro. Attached to the lifting strap is a strip or flap of material (a closure flap) of the remaining side of the hook and loop type fastener. The closure strap is positioned to allow the closure strap to bridge across the edge strip material and connect to the lined area on the strap, thereby preventing the side strap from sliding through the retention loop.
[0054] For explanatory purposes, suppose the “loop” side of the fastener is positioned suitably on the lifting strap. Attached to the closure strap is the mating “hook” material. The closure strap bridges the opening in the edge strip (or retention loop) in a closed loop by the join of the hook and loop attachment member, capturing the edge strip material there between, thereby substantially fixing the vertical position of the strap with respect to the to the edge strip. This prevents the lifting strips from slipping through the edge strip and separating the sling from the lifting bag. The fastener should not be used during lifting of a loaded bag, as a lifting stress will be transmitted to the exterior walls of the bag by the fastener, potentially causing the exterior fabric to tear or rip, an undesired result. See FIG. 4 of the '662 application for details of this vertical attachment.
[0055] The bag is then placed in a frame or container, the top zipper 1070 is opened and the top inverted “inside out” over the sides of the frame or container. The bag is then loaded. Once the bag is filled to the desired height, the top of the bag is re-inverted into an outside “out” relationship, and the zipper 1070 closed. Once closed, the two end wall triangular pieces 1060 A and B are folded down onto the top, and can be joined together with a strap or wire or rope to keep these triangles from flapping during transportation. The lifting bag, once loaded or filled, can be lifted using a lifting frame, such as shown in FIG. 8 U.S. Pat. No. 6,142,727 and FIG. 14 herein, (suitably modified for the number of straps on the bag to be lifted) or any other type of lifting frame known in the art. For instance, a square frame lifting frame may be used instead of the parallel lifting bars attached with a center support such as shown in FIG. 14 of the '662 application. Generally each side support member is a lineal element with a top and bottom end: the top end attaches to the lifting frame and the bottom end attaches to or is attached to the bottom support. Alternatively, a rope or webbing may be threaded through the top loops of the lifting straps, and a crane used to lift the filled bag. Alternatively, the lifting straps or side support members can be made sufficiently long to allow the top loops to be gathered together, joined, and lifted by crane or other lifting device.
[0056] Finally, it may be desirable to include a rain cap for the bag. During storage of a loaded bag, the bag will settle, and a valley may form in the top of the bag, generally near the centerline. Because the zipper 1070 is in the center of the top, the zipper 1070 can be a source of water leakage into the bag interior. To prevent this, a rain cap 2070 can be provided to cover the top, such as shown in FIG. 11 . One embodiment of such is a single piece of waterproof fabric that is draped over the bag's top and partially over the sides, and cinched down around the bag's top periphery using loops positioned along the bottom or sides of the bag, or off the belly strap or a similar location.
[0057] Finally, the bag can include a cinch straps positioned near the top four corners (preferably, two straps on each long side of the bag). The cinch straps can tie into the edge strip. For very large bags, additions cinch straps may be needed near the center of the bag. Cinch straps can be constructed from rope, polypropylene, polyester or other suitable material. The cinch straps runs vertically on the side of the bag and in use, allows the top of the bag to be drawn toward the bottom of the bag. A loop or connector can be attached to the bag as needed for coupling the cinch straps.
[0058] It is intended that the following claims be interpreted as covering all such alterations and modifications as fall within the true spirit and scope of the invention.
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A lifting bag having at least one side wall and a closed bottom forming an interior, the bag further having a closable top portion connected to the sidewall and adapted to close the interior of the bag. The opening is a single slit centered on the bag top and closable with a zipper. The lifting bag includes a sling coupled to the bag, generally through a edge strip positioned at ore near the top edge of the bag. The bag can be constructed from a single multilayered sheet. The bag is used in conjunction with a lifting strap system.
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FIELD OF THE INVENTION
This invention relates to apparatus for supplying natural gas fuel for the purpose of heating the boilers of tankers that transport liquefied natural gas (LNG).
BACKGROUND OF THE INVENTION
An LNG tanker is conventionally propelled by one or more steam turbines. The tanker is thus provided with boilers to raise the steam. About 50% of the fuel that is required to be burnt in order to raise the steam provided from the LNG storage tanks themselves of the tanker. Since liquid natural gas has a boiling point at a temperature of about minus 162° C., even though the storage tanks are thermally insulated, the boiling point of liquid natural gas is so low that there is inevitably a continuous boil-off of LNG from the tankers, albeit at a modest rate. Conventional operation is to employ such natural boil-off to meet a part of the requirements for fuel of the boilers. The balance is met from a stock of a heavy hydrocarbon liquid fuel, sometimes referred to as “bunker oil”.
It is however required that the tanker should have the capability of generating sufficient thermal energy from the combustion of the natural gas alone to raise all the steam required for its propulsion. Accordingly, the apparatus for supplying natural gas to the burners associated with the boilers additionally includes a forced vaporiser. In the tanker apparatus that has been used for the past 20 years there is a natural gas compressor which receives part of its feed from the ullage space of the LNG storage tanks and the remainder from the forced vaporiser. The forced vaporiser has an outlet temperature in the order of minus 40° C., chosen to be well above the dew point of the natural gas so as to ensure that there is no precipitation of liquid droplets in the inlet to the compressor. On the other hand the temperature of the natural gas taken from the ullage space of the tanks tends to be in the range of minus 100° C. to minus 140° C., the latter temperature obtaining when the tanker is fully laden with LNG, the former temperature obtaining when the tanker returns from making a delivery, a small amount of LNG having been retained for purposes of keeping the storage tanks at a suitable low temperature. In practice, therefore in this conventional apparatus the compressor has to be arranged so that it can operate at any natural gas inlet temperature in the range of minus 40° C. to minus 140° C. At the lower temperature the adiabatic work required to compress the gas is in the order of 20 to 25 kJ/kg whereas at the higher temperature it is in the order of 50 to 60 kJ/kg. The motor which drives the compressor therefore has to be able to cope with a wide range of duties. Typically, the motor is either provided with a frequency converter or is of a plural speed kind. Other disadvantages arise. In particular, it is necessary to employ a mist separator downstream of where the gas from the forced vaporiser is mixed with the natural boil-off gas so as to ensure that no particles of liquid are carried into the compressor, such particles being a potential source of liquid erosion damage to the impeller of the compressor.
There is therefore a need for an improved arrangement for providing natural gas as a fuel to raise steam in the boilers of the tanker and the invention aims at providing an apparatus that meets this need.
SUMMARY OF THE INVENTION
According to the present invention there is provided apparatus for supplying natural gas fuel to heat the boilers of an ocean-going tanker for the transport of LNG comprising a compressor having an inlet communicating with the ullage space of at least one LNG storage tank and an outlet communicating with a conduit leading from the compressor to fuel burners associated with the boilers, and a forced LNG vaporiser having an inlet communicating with a liquid storage region of the said tank and an outlet communicating with the same or a different conduit leading to fuel burners associated with the boilers.
The invention makes it possible to operate the compressor within a narrower temperature range, typically minus 140° C. to minus 100° C., thereby reducing greatly the amount of work required to compress the natural gas to a given pressure. As a result, a single speed motor without a frequency converter can typically be used to drive the compressor. Accordingly, the compressor drive arrangement is simplified. In addition, the power consumed by the compressor is reduced. There are two reasons for this. First, its average operating temperature is lower than in the known apparatus described above. Accordingly, the work needed to raise a unit quantity of this gas by a chosen pressure is less than in the known apparatus. Second, because the forced vaporiser exhausts downstream of the compressor, the rate of gas flow through the compressor is reduced in comparison with the known apparatus.
Preferably, the forced vaporiser has a second valve means to control the flow associated therewith, a first valve means operable to select its outlet temperature and a second valve means to control the flow rate of gas therethrough.
Typically, there is a gas heater downstream of the compressor. If the forced gas vaporiser communicates with the same conduit as the outlet from the compressor, the location in this conduit at which the forced vaporised gas encounters the compressed gas is preferably downstream of the gas heater.
BRIEF DESCRIPTION OF THE DRAWINGS
An apparatus according to the invention will now be described by way of example with reference to the accompanying drawings in which:
FIG. 1 is a schematic flow diagram of a first embodiment of the apparatus; and
FIG. 2 is a schematic flow diagram of a second embodiment of the apparatus.
Like parts in FIGS. 1 and 2 are indicated by the same reference numerals.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1 of the drawings, an LNG storage tank 2 is located on board an ocean-going tanker (not shown). The tank 2 is vacuum-insulated or has another form of thermal insulation associated therewith so as to keep down in flow of heat from the ambient environment into the liquid therein. The tank 2 has an ullage space 4 and contains a volume 6 of LNG. Since LNG boils at a temperature well below ambient, notwithstanding the thermal insulation of the tank 2 , there is a continuous evaporation of the LNG into the ullage space 4 . The resulting vaporised gas flows out of the tank 2 though an outlet 8 and passes along a pipeline 10 to a compressor (or blower) 12 . The compressor 12 is driven by an electric motor 14 . The motor typically has a single speed and does not employ a frequency converter. The pressure of the gas is raised by operation of the compressor 12 . The heat of compression is not nearly sufficient to raise the temperature of the gas being compressed to ambient temperature, such temperature being required for the operation of the boilers. The resulting compressed gas therefore passes through a gas heater 16 in which it is heated by steam (or other heating medium, e.g. hot water) so as to raise its temperature to approximately ambient temperature. To avoid overheating the gas, temperature control is provided by a valved by-pass line 20 extending from upstream to downstream of the gas heater 16 . As a further measure of temperature control, the gas heater has on its upstream side a flow control valve 18 which is able to set so as to select the outlet temperature therefrom. The resulting heated gas passes into a conduit 22 in which it mixes with a second flow of vaporised natural gas.
The second flow of vaporised natural gas is formed by employing a forced vaporiser 24 to vaporise a flow of LNG taken by a submerged pump 26 from the volume 6 of LNG within the tank 2 . The outlet of the pump 26 communicates with the forced vaporiser 24 via a riser 28 . A pressure control valve 48 opens a pipe 50 to allow liquid to be returned to the storage tank 2 for different flow rates through the vaporiser 24 . The forced vaporiser 24 has an enlarged superheating section to enable an outlet temperature of plus 20° C. to be readily achievable. The forced vaporiser 24 has an arrangement of valves similar to that associated with the gas heater 16 . Thus, there is a first flow control valve 30 on the upstream side of the vaporiser 24 to set the outlet pressure of the heater 16 so that it is equal to the outlet pressure of the compressor 12 , and a valved by-pass line 32 extending from upstream to downstream of the vaporiser 24 to control the outlet temperature of the vapour. The vaporiser 24 is typically of a kind which employs steam heating to raise the temperature of the fluid flowing therethrough.
The mixture of the gas supplied from the heater 18 and that supplied from vaporiser 24 passes through a master flow control valve 38 into burners 40 associated with boilers 42 in the engine room 44 of the tanker. The master flow control valve 38 is located in operation, the heat generated by firing of the burners 40 raises steam in the boilers 42 . Steam is used to drive a turbine (not shown) that provides propulsive power for the tanker.
The apparatus according to the invention preferably has various safety measures to cope with any unexpected operating conditions. For example, a surge valve 46 automatically opens a by-pass around the compressor 12 should a surge condition in the compressor 12 occur. Similarly, the submerged pump 26 is protected by the minimum flow by-pass valve 48 as described above.
In a typical example of the operation of the apparatus shown in the drawing, the compressor 12 receives boil-off gas from the ullage space 4 of the tank 2 at a temperature of minus 140° C. and as (absolute) pressure of 106 kPa. The gas is duly raised in pressure by operation of the compressor 12 to a pressure of 196 kPa. The exit temperature of the compressor 12 is in the order of minus 110° C. The gas heater 18 raises the temperature of the gas from minus 110° C. to plus 20° C. There is a small drop in pressure through the gas heater, typically in the order of 10 kPa. The gas which leaves the heater 18 is mixed with a gas stream at the same temperature and pressure from the forced vaporiser 24 . The feed to the forced vaporiser 24 is provided by the pump 26 at a pressure in the range of 300 kPa to 500 kPa and a temperature in the order of minus 160° C.
The above example applies to an instance in which the tank 2 is fully laden with LNG. Typically, not all the LNG is delivered at the tanker's destination. Some is retained for the purposes of cooling the storage tank 2 during the return journey to the LNG supply terminal. Typically, since the storage tank 2 contains much less LNG on the return journey, the temperature in the ullage space rises to something in the order of minus 100° C. Accordingly, the temperature of the outlet of the compressor 12 rises to about minus 70° C.
Although only one storage tank is shown in the drawing, in practice, a single assembly of compressor, gas heater and forced vaporiser is able to serve any number of storage tanks. The LNG tanker is typically required to have a standby compressor 56 , a standby (off-line) gas heater (not shown) and a standby vaporiser (not shown) which can be used in the event of any malfunction of the on-line components.
By having forced vaporiser 24 discharge into the heated gas stream rather than into the gas stream upstream of the compressor, a number of advantages can be obtained. Firstly, a simple single speed motor 14 may be employed to drive the compressor 12 . Secondly, the size of the compressor 12 and the motor 14 may be reduced. Thirdly, because the compressor receives only natural gas from the ullage space 4 of the vessel 2 , and does not have the output of the forced vaporiser mixed with it, its control is simplified. Fourthly, because a smaller motor can be used, energy savings result. In addition, energy savings are made possible by virtue of the fact that the gas from the forced vaporiser does not have to be recompressed.
Another advantage resides in the fact that no mist separator downstream of either the forced vaporiser or upstream of the compressor is required.
Typically the pump 26 is one that is normally provided in the tank 2 for other purposes. Thus, no dedicated liquid pump needs to be installed.
Various changes and modifications may be made to the apparatus shown in the drawing. For example, outlet from the forced vaporiser 24 may communicate with a conduit (not shown) other than the conduit 22 . Further the other conduit may communicate with a different burner or burners (not shown) from the ones in communication with the conduit 22 . In this alternative arrangement, the discharge pressure of the compressor 12 would be lower and therefore its size would be less than that shown in the drawing. Further, the flow control systems of the compressor 12 and the vaporiser 24 would become completely independent of one another. In addition, control of the operation of the burners would be facilitated. Such an arrangement is shown in FIG. 2 of the drawings. Now, only some of the burners 40 communicate with the conduit 22 . The remainder of the burners 40 communicate via a flow control valve 60 with the vaporiser 24 . The flow control valve 60 controls the flow or pressure downstream of the vaporiser 24 . Now the valve 30 is a temperature control valve which sets the downstream temperature. Typically, for low flow rates from the vaporiser 24 the pressure drop is insufficient to provide an adequate flow through the by-pass line 32 . Accordingly, if the by-pass line 32 is fully open, the position of the valve 30 is adjusted so as to throttle the inlet to the vaporiser 24 and hence cause more liquid to flow through the by-pass line 32 . Typically, a split range control may be used to adjust the valve 30 and the valve in the by-pass line 32 . Thus a 0 to 50% signal can be employed to open the valve in the by-pass line, and the remaining 50-100% signal is employed to operate the valve 30 so that it throttles the inlet to the vaporiser 24 . The same control principle may be used in the operation of the gas heater 16 .
In a modification of the apparatus shown in FIG. 1, the union of the conduit 22 with the outlet conduit from the vaporiser 24 , and the valve 38 may both be located within the engine room 44 .
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Apparatus for supplying natural gas fuel to heat the boilers of an ocean-going tanker for the transport of liquefied natural gas (LNG) comprises a compressor having an inlet communicating with the ullage space of at least one LNG storage tank and an outlet communicating with a conduit leading from the compressor to fuel burners associated with the boilers, and a forced LNG vaporiser having an inlet communicating with a liquid storage region of the said tank and an outlet communicating with the same or a different conduit leading to fuel burners associated with the boilers.
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] Polyethylene terephthalate is a polyester resin useful in preparing blow molded containers to contain a wide variety of liquids. It is desirable that the bottles have excellent strength and a high degree of clarity. Typically, such bottles are filled with liquid at a location remote from the location at which the containers are molded. The molded containers are commonly formed by the reheat-stretch-and-blow procedure. Tubular preforms closed at one end and open at the opposite end are injection molded of a suitable grade and formulation of PET.
[0003] The molded containers must be packaged and shipped to the location at which they are filled with liquid. The preforms are typically removed from the injection mold and allowed to cool to ambient temperature and are later introduced to a blow molding system when the preforms are first heated to a temperature within the glass-transition range of the material, then mechanically stretched in the longitudinal direction, and finally blow molded to the final container configuration and dimensions. The mechanical stretching and blow molding impart biaxial molecular orientation to the material of the container body, thereby enhancing the tensile strength of the body wall while reducing its thickness. The finished containers are of a great variety of sizes and configurations. The problems of designing a container from a PET material for a particular purpose presents an extremely wide variety of considerations including not only capacity and aesthetic appeal, but economy of material and, importantly, whether the container is to be filled with contents under pressure, as is the case with carbonated beverages, or under vacuum, as is the case with hot filled products.
[0004] Once the configuration of the container has been determined, a preform must be designed. Due to the necessity of conserving material and notwithstanding the ensurance that the material forming the container will be distributed properly in the finished container to ensure that it will exhibit resistance to deformation and rupture under all conditions of expected use, preform design has become an exact science.
[0005] When the PET containers are intended for use in packaging carbonated beverages subject to internal pressures of three to four atmospheres, a preform configuration has evolved in which the outer diameter of the closed end is smaller than the internal diameter of the open end, whereby one preforming, by way of its open end, receive the closed end of an adjacent preform. The procedure is referred as nesting. In certain instances when the nesting of two or more preforms occurs, two preforms may be locked together by a vacuum created in the enclosed zone between the outer surface of the inner preform and the contacting inner surface of the outer preform. This condition is an impediment to safety and efficient handling of preforms. Heretofore, it is necessary to detect and individually separate nested preforms before damage could occur to the preforms or the equipment in which they were being processed.
[0006] 2. Description of the Prior Art
[0007] To eliminate the above problem of nesting, the prior art, as illustrated in the U.S. Pat. No. 5,366,774 to H. M. Pinot et al. discloses a preform which in a well-known manner comprises a generally tubular body formed of synthetic resinous material about a central axis. The body is provided with an inner surface and an outer surface surrounding the central axis, a first end open to the inner surface, and a second end opposite to the first end. A narrow body portion is axially spaced from the second end. The outer surface of the narrow portion has a radial dimension slightly smaller than the radial dimension of the inner surface of the wide portion.
[0008] The anti-nesting feature includes an interference means formed on the inner surface at the wide portion to prevent the narrow portion of a similar preform from nesting within the wide portion of an adjacent preform.
[0009] The interference means comprise at least one projection protruding radially inwardly from the inner surface at the wide portion, such as in axially extending rib.
[0010] The interference means in the preferred embodiment includes, not one, but a plurality of inwardly protruding projections, such as ribs, spaced circumferentially about the inner surface. Each of the projections protrudes radially inwardly from the inner surface.
[0011] These inwardly extending ribs militate against the entry of the narrow portion of a similar preform from nesting within the wide portion of the neck finish of the preform. The configuration of the neck finish, once established, is not altered in the blow molding procedure and is carried over intact to the finished blown container. The inwardly extending ribs have no function in the finished container and are considered surpluses.
[0012] Another prior art structure designed to prevent nesting of adjacent preforms is illustrated and described in U.S. Pat. No. 5,756,172 to Frank E. Semersky. The patent discloses a preform having a generally tubular body formed about a central axis and having inner and outer surfaces surrounding the axis, a first end open to the inner surface, a second end opposite to the first end, a wide portion of the tubular body adjacent to the first end, a narrow portion of the tubular body axially spaced from the second end, the outer surface at the narrow portion being a radial dimension smaller than the radial dimension of the inner surface at the wide portion, at least one outwardly extending protrusion located along the outer surface at the narrow portion and protruding radially outward from the outer surface of the narrow portion a radial distance greater than the distance between the radial dimension of the outer surface of the narrow portion and the radial dimension of the inner surface of the wide portion to prevent a narrow portion of a similar preform from nesting within the wide portion.
[0013] The protrusions, being disposed in that portion of the preform which undergoes substantial stretching, tend to disappear and blend invisibly into the finished blow molded container.
[0014] It is an object of the present invention to produce a preform construction which militates against the locking of two preforms together, yet permits the nesting of the preforms.
[0015] Another object of the invention is to produce a preform of a design permitting the nesting of two or more adjacent preforms wherein the surface area contact between two nested preforms is minimized to prevent the creation of a vacuum in the closed area of the nested preforms.
[0016] The above as well as other objects of the invention may be achieved by a preform for a blow molded container comprising a generally tubular body formed about a central axis and having inner and outer surfaces surrounding the axis; a first end open to the inner surface, a second end opposite to and spaced from the first end; a wide portion of the tubular body adjacent the first end; a narrow portion of the tubular body spaced from the second end; the outer surface of the narrow portion having a radial dimension smaller than the radial dimension of the inner surface at the wide portion, wherein the improvement comprises:
[0017] at least one interruption in the inner surface at the wide portion and extending axially from the first open end toward the second end and protruding radially outwardly from the inner surface a sufficient amount to provide a passageway between the outer surface of the narrow portion of a similar preform and the inner surface of the wide portion to prevent a similar preform from sticking within the wide portion by vacuum.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The above objects and advantages of the invention will become readily apparent to those skilled in the art from reading the following detailed description of the invention when considered in the light of the accompanying drawings, in which:
[0019] [0019]FIG. 1 is a perspective view of a preform constructed in accordance with the present invention;
[0020] [0020]FIG. 2 is a side view of the preform constructed in accordance with the invention, as illustrated in FIG. 1, in a nested relation;
[0021] [0021]FIG. 3 is an end view of the preform illustrated in FIG. 2 taken from the left hand side thereof;
[0022] [0022]FIG. 4 is a perspective view of an alternative preform constructed in accordance with the present invention;
[0023] [0023]FIG. 5 is a side view of two preforms constructed in accordance with the invention, as illustrated in FIG. 4 in a nested relation; and
[0024] [0024]FIG. 6 is an end view of the preform illustrated in FIG. 5 taken from the left hand side thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0025] Referring to the drawings, and particular to FIGS. 1, 2, and 3 , there is shown a preform generally indicated by reference numeral 10 for forming a blow molded container intended for the packaging of contents under pressure such as carbonated beverages. The preform 10 has preferably been injection molded of polyethylene terephthalate and is ready to be reheated, stretched, and blow molded into final container configurations by the well-known blow molding procedure.
[0026] The preform 10 comprises a generally tubular body 12 having a central longitudinally extending axis and having an inner surface 14 and an outer surface 16 surrounding the central axis. A first end 18 of the preform 10 is open to the inner surface 14 . A second end 20 opposite to and spaced from the first or open end 18 , is closed in a generally hemispherical configuration.
[0027] A neck finish, generally represented at 22 , is provided adjacent the open end. The neck finish 22 includes male threads 24 adapted to mate with female threads formed in a conventional closure to be applied when the finished container formed by being blow molded from the preform 10 has been filled and the closure received over the open end 18 of the preform. The neck finish 22 also includes a circumferential flange 26 which is used in the handling of the preform and the resulting container on processing and filling lines. The flange 26 is also useful to the consumer in pouring from the container, since it assists in affording a firm grip on the neck thereof. The configuration of the neck finish 22 and the flange 26 once established in the injection mold, are not altered in the blow molding procedure, whereby they are structurally carried over intact to the blown container.
[0028] The remainder of the body 12 of the preform 10 in the embodiment illustrated in FIGS. 1, 2, and 3 includes three passageways 30 which extend longitudinal in a spaced apart parallel relation on the inner surface 14 . The passageways 30 commence at the first end 18 and typically terminate on the inner surface 14 at a point beyond the flange 26 . These passageways 30 are in the form of interruptions in the smooth inner surface 14 and will allow the preforms 10 to nest and will prevent the creation of a vacuum in the otherwise closed zone generally defined by the inner surface 14 of one preform 10 and the outer surface 16 of the nested preform 10 as illustrated in FIG. 2.
[0029] It will be understood that the vacuum which the present invention eliminates is caused by the nesting of warm preforms. When the temperature of particularly the outermost preform decreases, the outer preform tends to commence shrinking causing the tubular body to decrease in dimensional configuration and cause the inner surface to contact the outer surface of the inner nested preform thereby establishing a zone defined by the outer surface of the inner preform and the inner surface of the outer preform and the line of contact between the preforms. The pressure of the atmosphere within the defined zone decreases as the temperature decreases. The resulting vacuum condition causes the nesting preforms to stick together and thereby interfere with the handling thereof.
[0030] Since the embodiment of the invention illustrated in FIGS. 1, 2, and 3 provides a continuous communication between the outside atmosphere and the closed zone between the two nested preforms preventing the sticking together of the nested bodies and allowing easy disassembly thereof.
[0031] Another embodiment of the invention is illustrated in FIGS. 4, 5, and 6 wherein structural features which are the same as those illustrated in the embodiment illustrated in FIGS. 1, 2, and 3 utilize similar reference numerals with a prime (′) designation.
[0032] Referring to FIGS. 4, 5, and 6 , there is a preform generally indicated by reference numeral 10 ′ for forming a blow molded container intended for the packaging of contents under pressure such as carbonated beverages. The preform 10 ′ has preferably been injection molded of polyethylene therephthalate and is ready to be reheated, stretched, and blow molded into final container configurations by the well known blow molding procedure.
[0033] The preform 10 ′ comprises a generally tubular body 12 ′ having a central longitudinally exterior axis and having an inner surface 14 ′ and an outer surface 16 ′ surrounding the central axis. A first end 18 ′ of the preform 10 ′ is open to the inner surface 14 ′. A second end 20 ′, opposite to and spaced from the first or open end 18 ′, is closed in a generally hemispherical configuration.
[0034] A neck finish, generally represented at 22 ′, is provided adjacent the open end. The neck finish 22 ′ includes male threads 24 ′ adapted to mate with female threads formed in a conventional closure to be applied when the completed container formed by being blow molded from the preform 10 ′ has been filled and the closure received over the open end 18 ′ of the preform. The neck finish 22 ′ also includes a circumferential flange 26 ′ which is used in the handling of the preform and the resulting container on processing and filling lines. The flange 26 ′ is also useful to the consumer in pouring from the container, since it assists in affording a firm grip on the neck thereof. The configuration of the neck finish 221 and the flange 26 ′ once established in the injection mold, are not altered in the blow molding procedure, whereby they are structurally carried over intact to the blown container.
[0035] The remainder of the body 12 ′ of the preform 10 ′ in the embodiment illustrated in FIGS. 4, 5, and 6 include three rib members 32 which extend longitudinally in spaced relation and extend radially inwardly from the inner surface 14 ′. The rib members 32 produce passageways which commence at the first end 18 ′ and typically terminate on the inner surface 14 ′ at a point beyond the flange 26 ′. These passageways are in the form of interruptions in the smooth inner surface 14 ′ of one preform 10 ′ and the outer surface 16 ′ of the nested preform 10 ′ as illustrated in FIG. 5.
[0036] In each embodiment of the invention it will be appreciated that the invention effectively minimizes the surface area contact between two nested preforms; and eliminates the creation of a vacuum in the zone between the nested preforms. Also, the invention reduces the force required to separate nested preforms due to the reduction in the surface area contact during nesting.
[0037] In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be understood that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.
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A preform for a blow molded container provided a tubular body having inner and an outer surface having a first end open to the inner surface and a second closed end opposite to the first end. The relative dimensions of the ends being such that the closed end is receivable in the open end of a similar preform to nest therein. The open end is provided with a passageway to provide communication with the outside atmosphere to prevent formation of a vacuum and thereby enable disassembly of the nesting preforms.
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CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of priority of U.S. provisional application No. 62/054,075, filed Sep. 23, 2014, the contents of which are herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to fasteners and, more particularly, to fasteners having an externally threaded shaft and a drivable head, the head being provided with elements adapted for frictional contact with a driver capable of delivering torque to the threaded shaft.
[0003] As can be seen, there is a need for such fasteners that are not subject to over-torqueing.
SUMMARY OF THE INVENTION
[0004] In one aspect of the present invention, there is provided a torque-limiting fastener assembly, comprising: a fastener body having an externally threaded shaft and a drivable head, the head being provided with elements adapted for frictional contact with a driver capable of delivering torque to the threaded shaft, wherein the elements comprise flexible flanges/toggles that deflect at a predetermined torque to prevent further frictional contact between the driver and the head elements that is sufficient to drive said fastener.
[0005] These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a perspective view of an embodiment of the invention shown being tightened by a driving tool.
[0007] FIG. 2 is an elevational view of an embodiment of the invention.
[0008] FIG. 3 is a section view along line 3 - 3 in FIG. 1 shown in non-maximum developed torque state.
[0009] FIG. 4 is a section view line 3 - 3 in FIG. 1 shown in maximum developed torque state.
[0010] FIG. 5 is an exploded view of an alternate embodiment of the invention.
[0011] FIG. 6 is a section detail view of the alternate embodiment of FIG. 5 shown in assembled and in non-maximum-developed-torque state.
[0012] FIG. 7 is a section detail view of the alternate embodiment of FIG. 5 shown in assembled and in maximum-developed-torque state.
[0013] FIG. 8 is an exploded view of an alternate embodiment of the invention.
[0014] FIG. 9 is an exploded view of an alternate embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
[0016] Over and under tightening of fasteners lead to machine failure. Over torqueing a fastener can lead to screw/bolt breakage by torsional shear of the body of the fastener as well as drive head stripping rendering further tightening or loosening of the fastener impossible. Under tightening of fasteners can lead to failure of adequately joining members, machine failure due to vibrations, reduced performance and early failure of components.
[0017] Furthermore the user has no way of knowing if the screw has been properly tightened without looking up a tightening torque value and purchasing a torque limiting wrench or driver. Torque limiting of fasteners is conventionally accomplished using a torque wrench which requires the user to set a specific value. These wrenches are expensive and require calibration. Furthermore their ability to properly limit the torque depends on components which can degrade over time or when exposed to severe ambient conditions such as corrosion and extreme heat.
[0018] Existing visual torque indicating bolts do not limit the torque and rely on the user having a visible view of the bolt's head in order to assess if the indicating feature has changed color. In essence these devices are not torque limiting but torque indicating devices. Furthermore their ability to indicate torque relies on a color changing indicator installed on the head of the screw which can produce highly variable values. Torque indicating bolts are expensive and only allow the user to see if a certain torque range has been set. These devices are not true torque limiting in nature and rely on the user having a direct line of sight on the head of the screw. Over or under tightening can still occur using these devices.
[0019] A fastener with a built in torque limiting feature greatly simplifies the user experience of tightening a screw. The user does not have to buy additional specialized equipment or be burdened by properly setting the equipment or any calibration.
[0020] FIGS. 1-4 of the drawings illustrate one embodiment 10 of the torque limiting fastener of the invention which consists of externally threaded shaft 30 and drivable head 16 . The latter is depicted here as hexagonal; however, those skilled in the art will be aware that the invention is not limited to a drivable head having any particular geometry. The hexagonal head 16 comprises external faces 28 adapted to mate frictionally with internal faces (not shown) of driver tool 24 . Slots 14 in head 10 extend internally from the exterior of faces 28 to optional stress relief notches 22 on a line parallel to the clockwise adjacent face. The slots 14 define torque limiting flanges/toggles 12 having surfaces 18 which, when a predetermined torque is delivered to said fastener 10 by driving tool 24 , deflect toward and contact adjacent surface 20 . This deflection of the flanges/toggles 12 changes the geometry of the faces 28 such that there is insufficient frictional contact thereof with the internal faces of tool 24 to deliver the torque required to drive the head 16 and threaded shaft 30 .
[0021] It will be understood by those skilled in the art that the fastener of the invention is insertion torque-limiting where the screw thread is left handed and removal torque-limiting where the screw thread is right-handed.
[0022] FIGS. 5-7 illustrate a second embodiment 34 of the invention. The torque limiting fastener which consists of externally threaded shaft 38 , drivable head 36 and torque limiting insert 44 , adapted for insertion into and fixation within bore 40 in head 36 . Insert 44 is provided with grip protrusions 46 which mate with slots 42 in bore 40 to achieve secure fixation of insert 44 within head 36 . The insert 44 is provided with internal bore 45 , depicted here as hexagonal; however, those skilled in the art will be aware that, like drivable head 16 of the embodiment of FIGS. 1-4 , the invention is not limited to any particular geometry of bore 45 . Insert 44 comprises internal faces 49 adapted to mate frictionally with external faces 51 / 26 of driver tool 24 . Insert 44 is provided with slots 54 which extend internally from the exterior of faces 49 on a line parallel to the clockwise adjacent face. The slots 54 define torque limiting flanges/toggles 48 having surfaces 50 which, when a predetermined torque is delivered to the fastener 34 by driving tool 24 , deflect toward and contact adjacent surfaces 52 . This deflection of the flanges/toggles 48 changes the geometry of the faces 49 such that there is insufficient frictional contact thereof with external faces 51 / 26 of tool 24 to deliver the torque required to drive the head 34 and threaded shaft 38 .
[0023] FIGS. 8-9 illustrate a third embodiment 56 of the invention comprising externally threaded shaft 58 provided with internal bore 60 , torque limiting insert 64 provided with internal bore 63 and drivable head 70 . The insert 64 is provided with grip protrusions 66 which mate with slots 62 in bore 60 to achieve secure fixation of insert 64 within bore 60 . Similar to the insert 44 of FIGS. 5-7 , insert 64 is provided with flange/toggles 68 which, when a predetermined torque is delivered to fastener 56 by driving tool 24 , deflect sufficiently to changes their geometry such that there is insufficient frictional contact thereof with external faces 51 / 26 of tool 24 to deliver the torque required to drive the fastener 56 .
[0024] It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
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A torque-limiting fastener assembly, comprising: a fastener body having an externally threaded shaft and a drivable head, said head being provided with elements adapted for frictional contact with a driver capable of delivering torque to said threaded shaft, wherein said elements comprise flexible flanges/toggles that deflect at a predetermined torque to prevent further frictional contact between said driver and said head elements that is sufficient to drive said fastener.
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BACKGROUND OF THE INVENTION
This invention relates generally to methods and apparatus for magnetic resonance imaging (MRI) systems, and more particularly to methods and apparatus that facilitate making and using passive shim elements that provide for low eddy currents and an improved image stability.
Achieving a high final field homogeneity in MRI magnets typically requires the use of magnetic shimming, either a fully passive or a hybrid system that includes passive shims as an integral part. Shim elements made of magnetized steel, loaded strategically on shim rails, inserted inside the bore and saturated by the main field of the magnet, compensate for manufacturing tolerances and environmental inhomogeneities. These shim elements are exposed to pulsing fields from a plurality of gradient coils which generate heat in the shim elements, raising their temperature and thus affecting magnetic field stability (both B 0 and homogeneity) due to the temperature-dependent saturation B S (T) of the shims. Among major contributors to the shim heating are eddy currents induced in the conducting shims by the changing magnetic flux from the gradient coils. There is a need for efficient inexpensive passive shim elements with low eddy current heat generation.
BRIEF DESCRIPTION OF THE INVENTION
In one aspect, a MRI shim element includes a plurality of thin wires extending substantially parallel to each other wherein each wire has cross sectional dimensions less than δ sk , wherein δ sk is the wire's skin depth.
In another aspect, a method for making a plurality of shim elements is provided. The method includes placing a plurality of thin wires extending substantially parallel to each other to form either a flat sheet or an arced structure wherein each wire has cross sectional dimensions less than δ sk , wherein δ sk is the wire's skin depth, and cutting or punching the flat sheet or arced structure to form a plurality of shim elements.
In still another aspect, an imaging apparatus for producing Magnetic Resonance (MR) images of a subject is provided. The apparatus has a magnet assembly for producing a static magnetic field B 0 and a gradient coil assembly disposed within the magnet assembly for generating a magnetic field gradient for use in producing MR images, the apparatus includes a MRI shim element including a plurality of thin wires extending substantially parallel to B 0 .
In still another aspect, an imaging apparatus for producing Magnetic Resonance (MR) images of a subject is provided. The apparatus has a magnet assembly for producing a static magnetic field B 0 and a gradient coil assembly disposed within the magnet assembly for generating a magnetic field gradient for use in producing MR images, the apparatus includes a MRI shim element including a plurality of thin wires extending substantially perpendicular to B 0
DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a magnetic resonance imaging (MRI) system.
FIG. 2 illustrates two shim elements.
FIG. 3 illustrates that shim elements of different sizes can be cut out or punched out from a prefabricated composite wire/epoxy sheet.
DETAILED DESCRIPTION OF THE INVENTION
Herein described are methods and apparatus that provide a simple design to control the eddy currents generated in the shim elements during any gradient operational conditions.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
FIG. 1 illustrates a simplified block diagram of a system 10 for producing images to which embodiments of the below described shim elements of the present invention are applicable. Although a bore-type magnet is illustrated in FIG. 1 , the present invention is equally applicable to open magnet systems and other known types of MRI scanners. The MRI system could be, for example, a GE Signa MR scanner available from GE Healthcare which is adapted as described herein, although other systems could be used as well.
The operation of the MR system 10 is controlled from an operator console 12 , which includes a keyboard and control panel and a display (not shown). The console 12 communicates with a separate computer system 14 that enables an operator to control the production and display of images. The computer system 14 includes a number of modules, which communicate with each other through a backplane. These include an image processor module, a CPU module, and a memory module, known in the art as a frame buffer for storing image data arrays. The computer system 14 is linked to a disk storage or optical drive for storage of image data and programs, and it communicates with a separate system control 16 through a high speed serial link.
The system control 16 includes a set of modules connected together by a backplane. These include a CPU module 18 and a pulse generator module 20 , which connects to the operator console 12 through a serial link. The system control 16 receives commands from the operator, which indicate the scan sequence that is to be performed. The pulse generator module 20 operates the system components to carry out the desired scan sequence. It produces data that indicate the timing, strength, and shape of the radio frequency (RF) pulses which are to be produced, and the timing of and length of the data acquisition window. The pulse generator module 20 connects to a set of gradient amplifiers 22 comprising of G x , G y , and G z amplifiers (not shown) to indicate the timing and shape of the gradient pulses to be produced during the scan.
The gradient waveforms produced by the pulse generator module 20 are applied to the gradient amplifier system 22 . Each gradient amplifier excites a corresponding gradient coil in an assembly generally designated as 24 to produce the magnetic field gradients used for position encoding acquired signals. The gradient coil assembly forms part of a magnet assembly 26 which includes a polarizing magnet 28 and a whole-body RF coil 30 . A volume 32 is shown as the area within magnet assembly 26 for receiving a subject 34 and includes a patient bore. As used herein, the usable volume of a MRI scanner is defined generally as the volume within volume 32 that is a contiguous area inside the patient bore where the homogeneity of the main, the gradient and the RF fields are within known, acceptable ranges for imaging.
A transmitter module 36 in the system control 16 produces pulses that are amplified by an RF amplifier 38 coupled to RF coil 30 by a transmit/receive module 40 . The resulting signals radiated by the excited nuclei in the subject 34 may be sensed by the same RF coil 30 and coupled through the transmit/receive module 40 to a preamplifier 42 . The amplified MR signals are demodulated, filtered, and digitized in a receiver 44 . The transmit/receive switch 40 , is controlled by a signal from the pulse generator module 20 to electrically couple the transmitter 36 to the RF coil during the transmit mode and to connect the preamplifier 42 to the RF coil during the receive mode.
The MR signals picked up by RF coil 30 are digitized by the receiver module 44 and transferred to a memory module 46 in the system control 16 . When the scan is completed, an entire array of data has been acquired in the memory module 16 . An array processor (not shown) operates to Fourier transform the data into an array of image data. These image data are conveyed to the computer system 14 where they are stored. In response to commands received from the operator console 12 , these image data may be further processed by an image processor within computer system 14 and conveyed to the operator console 12 and subsequently displayed.
All commercial MRI systems employ passive shims to attain the desired final homogeneity of the uniform magnet field B 0 . A typical passive shim system includes a set of magnetized elements of predetermined different volumes/denominations, which allows one to create a desired magnetized moment on each shimming position. The degree of quantization in such a system is determined by the number of shim denominations and the volume of the smallest shim element. Passive shims are positioned inside the bore or within the gradient assembly, e.g. on the shim rails, in such a way that the multitude of available shimming positions would provide an adequate coverage of both axial and circumferential range, in order to enable compensation of both axial and radial harmonics representing B 0 inhomogeneity. In European patent application EP 0677751, the shim system employs shimming rings. Such rings due to their symmetry can be used to compensate axial harmonics only, while the need to compensate radial harmonics still remains. This need can be addressed by a separate set of discrete shim elements which unlike rings, do not have axisymmetric geometry and thus can allow variation of their circumferential distribution. The shim elements described below can be positioned on rails extending axially as well as circumferentially, and therefore provide full complete compensation for both axial and radial harmonics without resorting to additional rings, thus reducing complexity. In the radial direction, a stack-up of shim elements of different denominations within maximum allowable radial thickness, provides the desired total mass on each given position. System 10 , in some embodiments, includes shim elements as described below.
Herein described are shim elements that are composite and made of a parallel alignment of multiple long ferromagnetic steel wires held together by a filling material. The filling material can be epoxy, rubber, plastic, etc. When the shim elements are positioned on the rail, the wire orientation is typically parallel to the B 0 field of the magnet. However, the shim elements may be turned such that the wires extend perpendicular to B 0 and have a reduced magnetization. Additionally, the shim elements can be at any angle between being parallel and perpendicular to B 0 in order to achieve various shimming effects. Different sized shim elements would be employed to provide the desired quantization.
FIG. 2 illustrates two different shim element designs; a prior art shim 50 and a new shim element 60 . The main magnet field B 0 and gradient magnet field components are also shown in FIG. 2 . By reducing wire cross-sectional dimensions a, and b to be below the skin depth δ sk , one can reduce eddy currents caused by either dB r grad /dt, dB j grad /dt, or dB z grad /dt to any predetermined level. This is illustrated in FIG. 2 portions a) and b). The skin depth of the shim material equals to δ sk =√{square root over (2ρ/μμ 0 ω)}, where ρ is the material resistivity, μ is the material relative permeability, μ 0 is the permeability of vacuum, and ω is the gradient circular or angular frequency. In a saturated state inside the magnet, μ is close to one. With 1006 steel, for example, δ sk =6.6 mm at 1 kHz gradient frequency and is 21 mm at 100 Hz. In the conventional shim piece 50 where dimensions are much greater than ask, (as in 2 a ) eddy currents are flowing around the outer perimeter. In the herein provided configuration, rectangular or round wires 62 have dimensions less than δ sk , and very limited or no contact with each other. In some embodiments, the dimensions are much less than δ sk . For example, some embodiments use dimensions of ¼ δ sk and ⅓ δ sk . The eddy currents flow as indicated by an arrow in FIG. 2 b . The resultant heat generation in each wire is proportional to d 3 where d is the dimension normal to the magnetic flux from the gradients. Since the number of wires per piece (in each direction) increases as 1/d with smaller d, the total heat generation per piece is decreasing with wire diameter as proportional to d 2 . A central opening 64 in the shim elements allow for easy mounting on a stud or screw. However, the central opening is not necessary, and the shim elements may be mounted in other ways. For example, the rail may include a pocket sized to receive a shim element.
FIG. 3 illustrates that shim elements 60 of different sizes can be cut out or punched out from a prefabricated composite wire/epoxy sheet 70 . In one example, the wires 62 , either round or rectangular, are laid out and impregnated with a non-conductive bonding agent or filler material, such as, for example, epoxy. Additionally, in another embodiment, rather than constructing a flat sheet, the wires are wound around a drum or other jig and then the non-conductive bonding agent is applied. The arced structure from the winding around the drum may be flattened (bent straight) or left in an arc resulting in an arced shim element. In the embodiment with round wire, one advantage and technical effect is lower cost. The wires are either bare (limited linear contact), or pre-coated with varnish (no contact) and than impregnated by epoxy. The maximum attainable volumetric ratio (bare wire) is π/2·{square root over (3)}, or 90.7%.
In the embodiment with rectangular wire, one advantage and technical effect is higher volumetric magnetization (filling factor). Wires can be separated (either sleeved or interlaid e.g. by glass cloth or other non conductive material) prior to the impregnation. Additionally, multiple shim elements may be stacked in multiple layers either aligned as shown in FIG. 2 b , or offset as shown in FIG. 3 .
Exemplary embodiments are described above in detail. The assemblies and methods are not limited to the specific embodiments described herein, but rather, components of each assembly and/or method may be utilized independently and separately from other components described herein.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
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A MRI shim element includes a plurality of thin wires extending substantially parallel to each other wherein each wire has cross sectional dimensions less than δ sk , wherein δ sk is the wire's skin depth.
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BACKGROUND OF THE INVENTION
The problem of air pollution is not a new one. However, the problem has become more and more serious in many cities in recent years. Most of the pollution is a result of compounds which are derived from unburned or partially burned hydrocarbons found in the exhaust of internal combustion engines.
It is well known that noble metal such as platinum and palladium and combination of these metals have been and are currently being used in catalysts for the control of auto exhaust emissions. A wide variety of of activities can be achieved dependent on the choice noble metal salt used in the preparation. Since the use of noble metal auto exhaust catalysts is controlled to a great extend by cost, small amounts of noble metals must be used to maximum advantage. This means that the location and distribution of noble metals are of utmost importance in determining the intrinsic activity of the catalyst.
Several patents have been issued that disclose and claim conversion of exhaust gases to innocuous entities in the presence of platinum and palladium catalysts. In addition to being the principal components of these catalysts several of the noble metals are used in small amounts to promote activity of base metal systems. U.S. Pat. No. 3,189,563 of Hauel, issused June 15, 1965, is typical of the patents relating to the use of noble metal catalysts for the conversion of automobile exhaust gases. U.S. Pat. No. 3,455,843 to Briggs et al, issued July 15, 1969, is typical of a base metal catalyst system promoted with noble metal. Unpromoted base metal catalysts have been described in U.S. Pat. No. 3,322,491 by Barrett et al., issued May 30, 1967.
Normally the activity of a noble metal carbon monoxide and/or hydrocarbon oxidation catalyst can be increased by maximizing the dispersion of the noble metals. However, when the catalyst is used in an auto exhaust stream where gas velocities are high and contact times are short, the availability of the noble metal appears to be more crucial to high acitivity than the extent of dispersion. The reasons for this is that the rate of oxidation of carbon monoxide and hydrocarbons may be diffusion controlled. It is well known that a pelleted or balled catalyst operating under very high space velocity conditions, makes use of only the outer 5 to 10% of its volume for catalyzing the oxidation of hydrocarbons and carbon monoxide. Therefore, the best possible catalyst as far as performance is concerned is one in which the noble metals are located in the outer 5 to 10% of the pellet volume and one that is highly dispersed.
BRIEF DESCRIPTION OF THE INVENTION
We have found that if platinum and palladium are applied to a pelleted catalyst by means of a sulfito complex this high degree of dispersion and availability of the platinum and palladium results. These compounds have the emperical formula M 6 (x) (SO 3 ) 4 wherein M is Na+, K+ or NH 4 +, and x is platinum, palladium or mixtures thereof. The disulfito complexes, M 2 (x) (SO 3 ) 2 and M 2 (x) (SO 3 ) 2 (NH 3 ) 2 , can also be used in our process. The catalysts prepared using these sulfito complexes were found to have noble metals located near the surface of the pellet and have these noble metals moderately well dispersed.
DETAILED DESCRIPTION OF THE INVENTION
The first step of the process is the preparation of the sulfito complexes of platinum and palladium described above. Both platinum and palladium, unlike most metals, coordinate with the sulfite group, SO 3 = , in a monodentate fashion. Since both divalent platinum and divalent palladium prefer a square planar configuration, each metal can accommodate four sulfito groups. This opens up the unique possibility that the sulfito group can act as a bridging ligand and coordinate to two platinum atoms, to two palladium atoms or to a platinum and a palladium atom. Therefore, these sulfito complexes can be monomeric, dimeric or polymeric depending on the amount of bridging that takes place. The size of the noble metal sulfito polymer can be controlled by controlling the number of sulfite groups removed from the complex.
These large highly charged molecules, when impregnated onto pelleted supports, have little tendency to enter small pores in the support and probably decompose at the mouth of the pore or in very large pores. These large highly charged molecules also deposit very near the surface of the pellet in a reasonably dispersed manner. Both of these factors help prevent the rate of oxidation of CO and HC from being diffusion controlled and result in a catalyst of exceptionally high efficiency, especially with regard to control of auto exhaust emissions.
The first step in the preparation of our highly active and efficient catalyst is the selection of a suitable base. The preferred base is alumina or an alumina containing compound such as bauxite or the ultra stable base prepared by activating and stabilizing common alumina with metal oxides such as cerium oxide or other rare earth metal oxides at high temperatures prior to application of the noble metals.
The method of preparing this base is not part of this invention. Very briefly, the process consists of contacting suitable carrier supports such as mullite, spinel, silica, or alumina with a solution of a salt of a mixed rare earth, or more specifically a cerium salt in a quantity such that the final catalyst will contain from about 3 to about 10%, preferably about 5 weight percent cerium oxide expressed as Ce 2 O 3 . The support is then dried at a temperature of about 300°C. for about 6 hours followed by calcination at a temperature 1850° to 1950°F. for about 1 hour. The resulting activated and stabilized support has a surface area of about 75 to 125m 2 /g.
The next step of the process is the preparation of the solutions of platinum and palladium sulfito complexes. The method of preparing the complexes, of course, depends on the complex desired. These complexes can be readily prepared from chloroplatinic acid and palladium nitrate. In the process for preparing the alkali metal platinum sulfito complex or the alkali metal palladium/platinum sulfito complex the chloroplatinic acid and palladium nitrate solutions are prepared and treated with an excess of sodium bisulfite (NaHSO 3 ). The pH of the solution is increased to 8 by the addition of sodium carbonate.
The sodium bisulfite acts both as a reducing agent for the tetravalent platinum and as a complexing agent for the platinum and palladium. The alkali metal, preferably sodium, platinum sulfito complex and the mixed sodium palladium platinum sulfito complex are readily precipitated from the basic solution as a white or light yellow salt. This sodium palladium sulfito complex has a considerable solubility in basic solutions, but can be precipitated by cooling the solution. The addition of either acetone or ethanol decreases the solubility of the sulfito complexes in water.
After the salts have been precipitated they are filtered, washed with cold, very dilute, ammonia solution, and finally with acetone. The resulting stable complexes can be dried at 100°C. for periods of 1/2 to 2 hours. These complexes are thermally stable to temperatures above 300°C. and thus can be easily handled in the laboratory.
Another convenient method of preparing the mixed sulfito complex is to start with a metal sponge. In the first step of this preparation a mixture of platinum and palladium metal in sponge form is dissolved in the mixture of hydrochloric and nitric acids known as aqua regia. The dissolution is accomplished by heating the metals until the excess acid is boiled off. At that point the solution is diluted and filtered to remove undissolved metals. The pH of the solution is raised to about 5 with sodium carbonate and an excess of sodium bisulfite solution is added. The ph of the solution is raised to about 8 with sodium carbonate. After filtering, washing and drying the sodium salt of the mixed platinum and palladium complex is recovered. A greater than 90% yield of the complex is recovered using this technique.
The ammonium salts of the platinum and palladium sulfito complexes are also prepared from chloroplatinic acid and palladium nitrate solution, respectively. The ammonium platinum sulfito complex is prepared by treating chloroplatinic acid solution with an excess of ammonium bisulfite. Immediate precipitation of a white solid occurs after which a saturated solution of ammonium carbonate and ammonium hydroxide is added to make the pH basic. The slurry is cooled to 10°C. in an ice bath to decrease the solubility of this complex. The slurry is then filtered. The filter cake is reslurried with ammonium carbonate and ammonium hydroxide solution, and refiltered, and then washed with ethanol and dried in a vacuum oven. This complex is readily soluble in water and is stable to 250°C.
It has also been found that the specific complexes need not be isolated in order to prepare catalysts of good performance. Impregnating solutions of the complexes may be prepared by dissolving chloroplatinic acid in deionized water and bringing the solution to a boil. A small amount of the bisulfite solution (either sodium, ammonium or potassium) is added. A color change from orange to yellow to colorless occurs rapidly after which boiling is continued for 5 minutes. The solution is then cooled to room temperature. The desired amount of palladium nitrate is then added and the solution is ready to use for impregnating the base.
It has been found that a satisfactory complex may also be prepared using a simplified procedure. In this procedure the aqueous solution of chloroplatinic acid is heated to boiling temperature, sulfur dioxide is bubbled into the boiling solution and after an appropriate period of time (after the solution changes from orange to colorless) the addition of SO 2 is discontinued and the boiling is continued for an additional 5 minutes.
The solution is cooled to room temperature. If the solution is to contain palladium, then an appropriate quantity of palladium nitrate is added to the cooled solution. The solution is then ready to be used for impregnating the base.
The catalyst is prepared by cladding or impregnating the support with solutions of the mixed sulfito complex prepared by any of the methods disclosed above or of the individual platinum and palladium sulfito complexes. The impregnation may be made with a solution prepared by dissolving the complex in a suitable solvent. However, the complex can also be prepared in situ as pointed out above and need not be isolated during catalyst preparation.
After impregnation the catalyst is dried and activated. Activation may be carried out by either heating in air at temperatures of 800° to 1400°F. for periods of 1-4 hours or heating in a reducing environment such as hydrogen for 1/2 to 2 hours at 600°-800°F. A particularly satisfactory catalyst is obtained by calcination of the impregnated support at temperatures of 800° to 1200°F. for periods of 1 to 2 hours. The noble metals are present in the catalyst to the extent of 0.02 to 0.08% by weight based on the total weight of the catalyst.
The catalytic performance of the system was evaluated by both bench scale testing, as well as full-size engine tests. The engine test which was carried out employs a full-size catalytic converter similar to that which will be used on production vehicles equipped with catalytic hardware. This test is described in detail in a publication of the Society of Automotive Engineers entitled, "An Engine Dynamometer System for the Measurement of Converter Performance", by D. M. Herod, et al., that was presented at the Automotive Engineering Meeting in Detroit, Mich., on May 14-18, 1973, available from the Society of Automotive Engineers, Inc., Two Pennsylvannia Plaza, New York. N.Y. 10001 and is incorporated herein by reference. The essential feature of this process is the segmenting of the cycles into six segments. The first segment, designated CN, is the first 31 seconds cold cycle which is characteristic of very low conversion performance. C1 is interval between 31 and 205 seconds of the cold cycle characteristic of accelerating conversion performance. C2 is the remaining of the five cold cycles between 205 and 505 seconds characteristic of semi-stable conversion performance. Interval 4 (ST) is the time interval of the entire (13) stabilized cycles characteristic of stable conversion performance. H1 is the first 205 seconds of hot cycle characteristic of accelerating conversion performance. H2 is the remaining five hot cycles characteristic of semi-stable conversion performance. The predicted values are derived by inserting the actual values obtained in a formula as described in the publication of the Society of Automotive Engineers.
Since large quantities of catalyst must be prepared for evaluation in the engine test, a bench test was devised that would correlate with the engine test and would require the preparation of only small quantities of catalyst.
The bench test is designed to simulate the exhaust gas composition in heatup conditions experienced by a catalyst during the initial part of the actual chassis dynamometer run. The test approximates the environment the catalyst will experience during all important cold start and cold segment of the chassis test which accounts for a substantial portion of the total carbon monoxide emitted. The simulated exhaust gas contains 1600 parts per million carbon as propane, 4.5 volume percent oxygen, 10.0 volume percent water vapor, 3.0 volume percent carbon monoxide with the balance being nitrogen. The gas mixture is preheated so that the inlet gas temperature to the bed of catalyst is 600°F. As the hot gas passes through the room temperature catalyst the bed begins to heat up in a manner similar to the heat up in an actual catalytic device on an automobile. When the temperature in the bed becomes high enough, catalytic oxidation of the carbon monoxide and hydrocarbon in the stream commences and the temperature increases at an accelerated rate due to the heat of reaction. Catalyst performance is measured by determining the time and/or temperature relationships for given conversion of carbon monoxide and hydrocarbons. The more active catalysts tested in the engine test are those catalysts which in the bench test are characterized by the lowest Δt and the highest hydrocarbon efficiency. Δt is a measure of the time required to oxidize from 10 to 90% of the carbon monoxide in the simulated exhaust gas composition to carbon dioxide. Hydrocarbon efficiency refers to the maximum conversion of hydrocarbon observed after a specified time (10 minutes). This bench test is essentially a scaled down version of the engine test previously described. Carbon monoxide is determined by non-dispersive infrared analysis and hydrocarbon is determined by flame ionization analysis.
Our invention is illustrated by the following specific but nonlimiting examples.
EXAMPLE 1
This example illustrates a satisfactory method for preparing the noble metal catalyst. A total of 125 g. of chloroplatinic acid (40% platinum) were dissolved in 3 liters of deionized water. The solution was made basic by adding a solution containing 225 g. of sodium carbonate in 1 liter of water. A solution containing 225 g. of sodium bisulfite (NaHSO 3 ) in 1 liter of water was added to this solution. A precipitation occurred immediately. The slurry was stirred for an additional 30 minutes to ensure that all the chloroplatinic acid had been reduced to divalent platinum. The final solution was clear and the precipitate white. The solution was cooled in an ice bath to ensure complete precipitation of the platinum sulfito complex.
The slurry is then filtered, washed with several portions of cold dilute ammonium hydroxide solution prepared to contain 10 ml. of concentrated ammonium hydroxide in 1 liter of solution. The precipitate was washed with acetone to aid in drying. The white solid was dried at 110°C. The product had the formula Na 6 PT(SO 3 ) 4 and contained 28.4% platinum. The product was thermally stable to above 300°C.
The sodium palladium sulfito complex was prepared by diluting 200 ml. of a palladium nitrate solution prepared to contain 0.1 g. of palladium per ml. to 2 liters with water. A total of 120 g. of sodium bisulfite (NaHSO 3 ) in 500 ml. of water and 250 g. of sodium carbonate in 1 liter of water were mixed and poured slowly into the well stirred palladium nitrate solution. Considerable quantities of carbon dioxide were evolved. The resulting solution was stirred for a short time, cooled in an ice bath and filtered. The light yellow solid was washed with small quantities of very dilute cold ammonium hydroxide followed by washes with acetone. The product Na 6 Pd(SO 3 ) 4 was dried at 110°C. The salt decomposes at about 325°C. and was found to contain 18.47% palladium.
The impregnation solution was prepared by adding the sodium platinum sulfito complex and the sodium palladium sulfito complex to a small amount of water. Dilute nitric acid was slowly added over a period of 10 to 15 minutes till the salts dissolved. The final pH of the solution was about 5. The solution was finally diluted to the desired volume and sprayed to incipient wetness on a ceria stabilized alumina base that had been calcined for 1 hour at 1800°F. The impregnated base was dried at 300°F. and calcined for 2 hours at 1200°F. The catalyst contained 0.043 wt. percent platinum and 0.013 wt. percent palladium.
EXAMPLE 2
This example illustrates an alternate method of preparing a specific mixed sodium platinum-palladium sulfito complex. A total of 20 g. of chloroplatinic acid (H 2 PtCl 6 .sup.. 6H 2 O) containing 40% platinum and 32 ml. of a palladium nitrate solution containing 0.1 g. of palladium per ml. were dissolved in 1 liter of deionized water. A solution was prepared to contain 60 g. of sodium bisulfite (Na HSO 3 ) in 1 liter of water which was added to the palladium platinum salt solution. The resulting solution was neutralized by adding a solution of sodium carbonate prepared to contain 60 g. of sodium carbonate and 1 liter of water. A light yellow precipitate formed when the solution began to turn basic. After settling for 15 minutes the solution was cooled, filtered, washed with a small quantity of cold dilute ammonium hydroxide solution followed by an acetone wash and the product was dried at 100°C. for 30 minutes. A yield of 96% of the theroetical was recovered, the product, Na 6 Pt 0 .58 Pd 0 .42 (SO 3 ) 4 was found by analysis to contain 25.23% Pt-Pd and had a decomposition temperature of 335°C.
EXAMPLE 3
This example illustrates the method of preparing the ammonium salt of the platinum sulfito complex.
A total of 41 grams of chloroplatinic acid (40% platinum) was dissolved in 250 ml. of water. Two hundred ml. of ammonium bisulfite solution (prepared as a concentrated solution by dissolving ammonium carbonate (NH 4 ) 2 CO 3 in concentrated ammonium hydroxide solution) was added with considerable effervescence and a slight exotherm. The slurry was then cooled to 10°C. in an ice bath and was filtered. The filter cake was reslurried in concentrated ammonium carbonate-ammonium hydroxide solution and then refiltered. The voluminous white precipitate was then slurried in ethanol, filtered and washed with more ethanol and finally dried in vacuo at 105°C.
A yield of 70% of the theoretical was recovered; the product (NH 4 ) 6 Pt(SO 3 ) 4 was found by analysis to contain 31.47% platinum. The fluffy white powder is readily soluble in water and had a decomposition temperature of over 250°C.
EXAMPLE 4
This example illustrates a method for preparing the ammonium palladium complex.
A complex of 19 g. of palladium nitrate Pd(NO 3 ) 2 containing 46.81% palladium was treated with 40 ml. of concentrated ammonium bisulfite solution. The reaction occurred immediately with a formation of a green solid. The mixture was allowed to stand for 1 hour after which it was filtered and washed with a small quantity of cold water. It was then dispersed in ethanol, filtered and washed with more ethanol. It was dried at 105°C. in vacuo yielding 20.1 g. of product which contains 36.33% Pd. This represents a yield of 77%. The empirical formula of the product was (NH 4 ) 2 Pd(SO 3 ) 2 . The NH 4 +/palladium molar ratio of the compound was found to be 2.34 to 1.
EXAMPLE 5
3250 grams of an alumina support which contains 5% ceria expressed as Ce 2 O 3 was impregnated to approximately 30% of its pore volume with 345 ml. of a solution containing 622 mg. of palladium from palladium nitrate and 10.25 g. of cerous nitrate Ce(NO 3 ) 3 .sup.. 6H 2 O. To the remainder of the pore volume was added a solution containing 4.144 g. of the ammonium platinum sulfito complex dissolved in 805 ml. of H 2 O. The impregnated support was oven dried at 320°F. for 4 hours after which it was calcined for 2 hours at 1200°F. The finished catalyst contains .017 wt. percent palladium and 0.042 wt. percent platinum.
EXAMPLE 6
3.26 grams of chloroplatinic acid (containing 1.304 grams of Pt) was dissolved in 600 cc. of water and brought to boiling. Ten milliliters of a solution of sodium bisulfite (containing 3 grams of NaHSO 3 ) was added, after which boiling was continued for 5 minutes. 5.22 cc. of a palladium nitrate solution (containing 522 mg. palladium) was added and the solution was then diluted to 1020 cc. It was then impregnated onto 3240 grams of alumina extrudates containing 5% ceria expressed as Ce 2 O 3 . The impregnated extrudates were dried at 300°F. for 2 hours. This catalyst was activated in a 5% H 2 /95% N 2 atmosphere at 650°F. for 1/2 hour.
EXAMPLE 7
The procedure used for the sodium complexes above was repeated except that 6 cc. of ammonium bisulfite solution (containing 45% by weight NH 4 HSO 3 ) was substituted for the NaHSO 3 .
EXAMPLE 8
This example illustrates the effectiveness of the sulfito complex in allowing lower levels of noble metals to be used. This catalyst is prepared from the sulfito complexes using gaseous sulfur dioxide.
0.913 g. of chloroplatinic acid was dissolved in 600 ml. of water and brought to boiling. Sulfur dioxide was introduced through a gas dispersion tube for 31/2 minutes at a flow rate of 0.7 g. of sulfur dioxide per minute. After sulfur dioxide addition was stopped, boiling continued for 5 more minutes. The platinum sulfito complex was cooled to room temperature and 1.46 ml. of palladium nitrate solution containing 146 mg. of palladium was added. The total solution volume was adjusted to 1200 ml. and applied to 1845 g. of gamma alumina extrudates. The impregnated extrudates was dried at 300°F. then activated in a 5 volume percent hydrogen balance nitrogen atmosphere for 1/2 hour at 650°F. The final catalyst contains 0.008 weight percent palladium and 0.020 weight percent platinum.
EXAMPLE 9
This example illustrates the preparation of a platinum-palladium sulfito complex using gaseous sulfur dioxide.
A total of 1.892 grams of chloroplatinic acid (containing 0.757 grams of platinum) was dissolved in 600 ml. of water and brought to boiling, at which time sulfur dioxide was bubbled through a gas dispersion tube at a rate of 0.5 g. of sulfur dioxide per minute. The sulfur dioxide addition was continued for 71/2 minutes. The boiling was continued for an additional 5 minutes after sulfur dioxide addition ceased. The solution was then cooled to room temperature in an ice bath and 3.1 cc. of a palladium nitrate solution containing 100.5 milligrams palladium per ml. was added.
The solution was stirred and transferred to a reservoir for use in impregnating the alumina extrudates that had a surface area of 96 m 2 /g. and pore volume of 0.62 cc/g. The impregnation was carried out by passing the solution from the reservoir in a steady stream into 2000 g. of support in a mixing bowl. The impregnated extrudates were then transferred to trays and placed in an oven and heated to 320°F. The drying was continued for a period of 2 hours and activation was then carried out by heating to a temperature of 800°F. for 1 hour.
To illustrate the improvement in catalyst performance when sulfito complexes of this invention are employed, we include a catalyst which has been prepared by impregnating the same quantity of platinum and palladium as in Examples 1, 2, 5, 6 and 8 onto an alumina base using chloroplatinic acid and palladium nitrate solutions. The data for this preparation are set out in Table 1 below:
TABLE 1______________________________________ Predicted Results for a Proto- type 1975 GM Test Vehicle, gms/mileCatalyst HC CO______________________________________Non-Sulfito 0.228 2.278______________________________________
When the same test procedure was performed using the catalysts prepared by the methods of Examples 1, 2, 5, 6, 7 and 8 greatly improved results were obtained.
The data are set out in Table II.
TABLE II__________________________________________________________________________Catalyst Example Method of Addition Predicted Results for of Sulfito a Prototype 1975 GM Complex Test Vehicle, gms/mile HC CO__________________________________________________________________________1 Na.sub.6 Pt(SO.sub.3).sub.4 0.207 2.5161 Na.sub.6 Pd(SO.sub.3).sub.4 0.148 1.7732 Mixed Salt Na.sub.6 Pt.sub..58 Pd.sub..42 (SO.sub.3).sub.4 0.156 1.9392 Mixed Salt Na.sub.6 Pt.sub..35 Pd.sub..65 (SO.sub.3).sub.4 0.152 1.8362 Mixed Salt Na.sub.6 Pt.sub..18 Pd.sub..82 (SO.sub.3).sub.4 0.138 1.7705 (NH.sub.4).sub.6 Pt(SO.sub. 3).sub.4 0.166 2.0126 Nonisolated Sodium 0.150 1.841 Sulfito Complexes H.sub.2 Reduced Air Calcined 0.164 1.9337 Nonisolated Ammonium 0.153 1.787 Sulfito Complexes8 Gaseous Sulfur Dioxide 0.155 1.866 (.028% Total Noble Metal)8 Gaseous Sulfur Dioxide 0.140 1.832 (.056% Total Noble Metal)__________________________________________________________________________
It is apparent from these data that results obtained on catalysts prepared from the platinum-palladium sulfito complexes exhibit a substantial improvement in carbon monoxide and hydrocarbon oxidation activity over mixed platinum-palladium catalysts prepared by conventional means. Catalysts prepared from Na 6 Pt(SO 3 ) 4 alone are only moderately active as automotive exhaust oxidation catalysts. At least some palladium needs to be present along with the platinum.
EXAMPLE 10
This example illustrates that using the platinum and palladium sulfito complexes, active catalysts can be prepared on low grade supports such as raw bauxite ore.
A total of 58.9 mg. of the sodium platinum sulfito complex (containing 28.8% Pt) and 36.7 mg. of the sodium palladium sulfito complex (containing 18.5% Pd) were mixed with 30 ml. water and brought to boiling. After 10 minutes of boiling the complexes completely dissolved. The solution was then applied by impregnation to 49.5 grams of bauxite extrudates which has been calcined at 1650°F. for 1 hour and have a surface area of 120 m 2 /g. and pore volume of 0.6 cc/g. The impregnated bauxite extrudates were dried at 300°F. for 1 hour. They were then activated in a 5 volume percent hydrogen-balance nitrogen atmosphere at 650°F. for 1/2 hour.
EXAMPLE 11
This example illustrates that the sulfito complexes allow the degree of platinum and palladium penetration to be controlled by the pH of the impregnating solution.
A total of 391 mg. of chloroplatinic acid (40% platinum) was dissolved in 60 ml. of water and heated to boiling. Gaseous sulfur dioxide was added for 131/2 minutes at a rate of 0.3 g. of sulfur dioxide per minute. After sulfur dioxide addition was stopped boiling continued for 5 minutes. The solution was cooled to room temperature at which time 6.26 ml. of palladium nitrate solution containing 100.5 mg. palladium per ml. was added. The total volume was increased to 210 ml. and then the solution split into three equal portions. Two solutions were treated with nitric acid to adjust the pH to 0.93 and 0.42, respectively. The untreated sample had a pH of 1.5. Each solution was impregnated onto 139 grams of alumina extrudates. The impregnated extrudates were dried at 300°F. and finally activated in air at 800°F. for 1 hour. It was observed that the lower the pH the greater the degree of penetration into the extrudate particle.
EXAMPLE 12
This example illustrates the preparation of the palladium sulfito complex by the gaseous sulfur dioxide procedure and the subsequent use in preparing a catalyst.
3.65 ml. of palladium nitrate solution containing 10 mg. palladium per ml. was mixed with 80 ml. of water. Gaseous sulfur dioxide was bubbled in through a gas dispersion tube for one minute at a rate of 0.5 g. sulfur dioxide per minute. The color changed immediately from brown to green. This solution was then applied by impregnation to 132 g. of gamma alumina extrudates having a surface area of 114 m 2 /g. and a pore volume of 0.65 cc/g. The impregnated extrudates were dried and finally activated in air at 800°F. for 1 hour. This catalyst contains 0.028% by weight palladium.
Bench scale activity results of Examples 8-12 are setforth in Table III. Several engine tested samples are included for reference.
TABLE III______________________________________ Bench Activity Data CO HCCatalyst Example t-Seconds Efficiency -- %______________________________________Non-sulfito 48.2 56.08(.028% Total noble metal) 24.1 81.28(.056% Total noble metal) 18.7 86.79(Preferred sulfito complex) 21.3 83.110(Bauxite support) 23.2 81.611(pH =1.5) 26.2 83.611(pH =.93) 23.1 83.211(pH =.42) 27.2 74.412(.028% Palladium) 19.9 81.8______________________________________
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A process for preparing a catalyst that has improved activity and efficiency for conversion of hydrocarbons is disclosed. The catalyst is prepared by applying sulfito complexes have the emperical formula M 6 (x) (SO 3 ) 4 where M is H+ NA+, K+ or NH 4 + and x is platinum, palladium or mixtures thereof. In addition, the compounds M 2 (x) (SO 3 ) 2 and M 2 (x) (SO 3 ) 2 also have utility in our process. The complex salt is impregnated onto a support and activated by calcination in air or heating in a reducing atmosphere.
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BACKGROUND
[0001] 1. Field of the Invention
[0002] The present disclosure relates to a roof lining for a vehicle and a manufacturing method thereof, and in particular, to the roof lining for a vehicle using a composite resin material having basalt fibers mixed into a thermoplastic resin as a substrate. The resulting roof lining can achieve desired properties including lightweight, enhanced sound absorbency, stiffness and increased heat insulating properties. With the use of basalt fibers, the roof lining is more easily recycled.
[0003] 2. Description of the Related Art
[0004] A roof lining having good sound absorbency and heat insulating properties is normally mounted on an interior face side of a roof panel of a vehicle. As shown in FIG. 11 , a typical roof lining has a surface skin layer 3 having pleasing tactile properties and appearance attached to a front face side of a substrate 2 having shape retaining properties and sufficient stiffness for mounting on the roof panel. The substrate can also have a multilayer lamination structure having a backside nonwoven fabric 4 attached thereto for increasing the sound absorbency of the roof lining.
[0005] A polypropylene (“PP”) resin mixed with glass fibers is typically used for the substrate 2 as shown in FIG. 12 . The material can have a compounding ratio of PP resin 45 weight % to glass fibers 55 weight %. A hot-melt film 2 a , for instance, a polyamide resin film, for increasing enhancing adhesiveness to the facing 3 is laminated on the front face side of the substrate 2 while an air-impermeable layer 2 b consisting of a polyamide resin film is laminated on the backside of the substrate 2 . Thus, a configuration for preventing dust and the like from adhering to the front face side of the roof lining 1 is obtained.
[0006] For the surface skin layer 3 , a nonwoven fabric having a relatively heavy weight of 200 g/m2, or a cloth having a weight of 130 g/m2 can be used. As for the backside nonwoven fabric 4 , a polyester nonwoven fabric of the weight of 15 g/m2 and elongation of about 50% is be used. The configuration of a conventional roof lining is described in detail in Japanese Patent Application Publication No. 2004-74951.
[0007] Thus, in the case of using a polyolefin resin with glass fibers as the material for the roof lining 2 , a roof lining having the requisite stiffness and high sound absorbency along with good dimension stability is obtained. On the other hand, there is the problem of recycling the roof lining. Upon recycling of the glass fiber-containing roof lining by incineration, the glass fibers typically melt, or partially melt, and form an undesirable residue in the incinerator. The removal of the glassy residue from the furnace walls results in maintenance requiring many man-hours.
[0008] Thus, there is a problem that the roof lining composed of a polyolefin resin mixed with glass fibers cannot be easily recycled.
SUMMARY OF THE PRESENT DISCLOSURE
[0009] The present disclosure is directed to a method for producing a roof lining for a vehicle by forming a web including basalt fibers and a resin composition, heating the web to a temperature sufficient to melt the resin composition, and pressing the web into a blank with a first thickness. The blank is then heated to a temperature sufficient to melt the resin composition, and press formed to form the roof lining.
[0010] The forming of the web includes providing a resin binder and basalt fibers, contacting the resin binder and the basalt fibers, and adding a solvent to the contacted resin binder and basalt fibers. The solvent, resin binder and basalt fibers are mixed to form a slurry, which is supplied to a headbox, and then transferred from the headbox onto a conveyer. While on the conveyer, a vacuum is applied to the slurry to form the web, and also to partially remove the solvent from the slurry.
[0011] The present disclosure also includes a roof lining for an automotive vehicle having a substrate having a front face and a back face, and a surface skin layer adhered to a front face of the substrate. The substrate is formed from a mixture of basalt fibers three-dimensionally intertwined with one another and a thermoplastic resin binder. The mixture of basalt fibers and a thermoplastic resin binder having been heated twice to a temperature sufficient to melt the thermoplastic resin binder.
[0012] To solve the problem of recycling the roof lining containing glass fibers, the presently disclosed roof lining containing basalt fibers mixed in a thermoplastic resin was developed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings, which are included to provide a further understanding of the present teachings and are incorporated in and constitute a part of this specification, illustrate various exemplars of the present teachings and together with the detailed description serve to explain the principles of the present teachings. In the drawings:
[0014] FIG. 1 is an external view showing a roof lining for a vehicle according to the present teachings;
[0015] FIG. 2 is a sectional view showing a configuration of the roof lining for a vehicle;
[0016] FIG. 3 is an enlarged sectional view showing relations among elements configuring the roof lining for a vehicle;
[0017] FIG. 4 is an explanatory diagram showing an overview of a manufacturing method of the roof lining for a vehicle according to the present teachings;
[0018] FIG. 5 is an explanatory diagram showing a lamination process of a web and a film for materials of the roof lining for a vehicle;
[0019] FIG. 6 is a diagram showing a cross section structure before heating of a substrate used for the roof lining for a vehicle;
[0020] FIG. 7 is an explanatory diagram showing a heating process in the manufacturing method of the roof lining for a vehicle according to the present teachings;
[0021] FIG. 8 is a diagram showing a heated and expanded state of the substrate of the roof lining for a vehicle according to the present teachings;
[0022] FIG. 9 is an explanatory diagram showing a setting step of the materials in the manufacturing method of the roof lining for a vehicle according to the present teachings;
[0023] FIG. 10 is an explanatory diagram showing a cold press forming step in the manufacturing method of the roof lining for a vehicle according to the present teachings;
[0024] FIG. 11 is a sectional view showing a configuration of a conventional roof lining for a vehicle; and
[0025] FIG. 12 is an explanatory diagram showing elements of a conventional roof lining for a vehicle.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The present teachings are directed to a method for producing a roof lining for a vehicle by forming a web comprising basalt fibers and a resin composition, and heating the web to a temperature sufficient to melt the resin composition. The web is then pressed into a blank having a first thickness. The blank is then heated to a temperature sufficient to melt the resin composition, and then press formed to form the roof lining.
[0027] Forming the web is itself a multi-step process involving providing a resin binder and basalt fibers, and contacting the resin binder and the basalt fibers. Then adding a solvent to the contacted resin binder and basalt fibers; although in some embodiments, all three components can be contacted together simultaneously. The solvent, resin binder and basalt fibers are mixed to form a slurry or mixture. The slurry is then supplied to a headbox. Suitable headboxes include, for instance, headboxes used by the papermaking industry to distribute paper pulp material onto a forming fabric or wire screen, and described, for instance, in U.S. Pat. Nos. 6,733,627 and 6,004,431. The slurry is then transferred from the headbox onto a conveyer where a vacuum is applied to the slurry on the conveyer to form the web. The vacuum partially removes the solvent from the slurry, and helps the web to form on the conveyer.
[0028] In the present method, water can be utilized as the solvent, and the resin binder can be in a powder form.
[0029] The present method can further include the step of contacting one side of the web with a first film and the other side of the web with a second film after heating the web. In some instances, the first film can be an air-impermeable film and the second film can be an adhesive film. The second film, especially an adhesive film, can be contacted with a surface skin layer after heating the blank and prior to or, in some embodiments, during press forming.
[0030] The pressing of the web in the present method results in a crushing of the basalt fibers, and a fixing of the basalt fibers in a biased direction in the resin composition. The pressing of the web can be accomplished by laminating the web by a nip roller, or other suitable rolling or compression apparatus.
[0031] The present method also includes cutting the blanks to the desired dimensions for the roof lining. This cutting step can occur after the web is pressed into a blank with a first thickness. Width cutters and length cutters, as utilized in continuous manufacturing processes, can be used in the presently disclosed method.
[0032] Upon heating the blank, the thickness of the blank changes from the first thickness, obtained after pressing the web into the blank, to a second thickness. The heating of the blank can be accomplished by using, for instance, an infrared oven to heat the blank to a temperature sufficient to melt the resin composition.
[0033] In some embodiments of the present method, the first thickness ranges between about 2 mm to about 4 mm, and the second thickness ranges between about 5 mm to about 7 mm. The increase in thickness upon the second heating is the result of the expansion or relaxation of the compressed basalt fibers forming spaces between fibers or forming air pockets within the blank after the blank is heated. The formation of the air pockets provides the heated blank with a second thickness, that can be, and in most embodiments is, different from and greater than the first thickness.
[0034] The press forming step of the present method can occur in a cold press forming die apparatus. In some instances, the resin composition can be allowed to substantially cool prior to press forming.
[0035] A roof lining for an automotive vehicle is also provided by the present teachings. The presently taught roof lining includes a substrate having a front face and a back face, and a surface skin layer adhered to a front face of the substrate. The substrate includes a mixture of basalt fibers three-dimensionally intertwined with one another and a thermoplastic resin binder. The mixture of basalt fibers and a thermoplastic resin binder is heated twice to a temperature sufficient to melt the thermoplastic resin binder.
[0036] In the roof lining according to the present teachings, the thermoplastic resin binder can be present in a concentration ranging from between about 20 and about 80 weight percent, and the basalt fibers can be present in a concentration ranging from between about 20 and about 80 weight percent.
[0037] The basalt fibers used in the present roof lining include fibers with an average diameter ranging from between about 10 microns to about 20 microns, and with an average length ranging from between about 20 microns to about 50 microns.
[0038] The present roof lining can also include an adhesive film located between the front face of the substrate and the surface skin layer. It can further include an air-impermeable film located on the back face of the substrate. The air-impermeable film can also have a back side located away from the substrate. A non-woven material can be located on the back side of the air-impermeable film in some exemplars of the present roof lining.
[0039] Within the substrate, the basalt fibers can be fixed by the thermoplastic resin binder in a state of being three-dimensionally intertwined with each other. A cross sectional structure of the substrate reveals that the basalt fibers are crushed and biased in a pressed down or fallen state, as shown in FIG. 6 . The blank M has basalt fibers 21 fixed in the resin binder 22 . In this particular state, the basalt fibers 21 are crushed and fixed in a flattened biased direction.
[0040] In various embodiments of the present teachings, the blank is reheated before forming the roof lining, and the resin binder melts. The melting of the resin binder allows the basalt fibers to rise and thus the blank expands. This reheating step is followed by a cold press process so that the basalt fibers can be maintained in the expanded state. The basalt fiber expanded state can result in an increased amount of air gaps and spaces between the basalt fibers intertwined and set inside the resin binder.
[0041] As shown in FIG. 8 , upon heating, the resin binder 22 melts and any load previously applied to the basalt fibers 21 by the step of pressing the web into a blank is eliminated so that the basalt fibers 21 rise. The heated blank swells and the thickness of the blank M increases.
[0042] The dimensions of the basalt fibers can influence the properties of the roof lining, such as, sound absorbency, weight and stiffness. Additionally, the ratio between the basalt fibers and the binder thermoplastic resin can influence the properties of the roof lining, for example density. Basalt fiber dimensions and ratio between the fibers and the resin can be adjusted and selected according to not only the desired properties of the finished article but also the dimension and thickness of the finished article, shape of the roof lining and other factors. One of skill in the art will recognize the factors to be considered in making such selections.
[0043] The roof lining of the present teachings can also have an enhanced film or the like laminated on both sides of the blank for the purpose of reinforcing the stiffness. Additional embodiments can include an air-impermeable film laminated on the backside of the blank to prevent dust and the like from adhering to the front face side of the product, and a configuration in which a polyamide hot-melt film for enhancing adhesiveness to the surface skin layer or facing is attached.
[0044] A method of making paper from pulp can be adopted to the presently taught method of producing a roof lining. Initially, the basalt fibers and resin powder are separately provided to a mixing container. Water can be present in the mixing container, or added after addition of the basalt fibers and the resin powder. The three components can be mixed by stirring to form a slurry. The slurry can be supplied to a papermaking headbox, as described above.
[0045] The slurry can then be distributed by the headbox onto the conveyer. The conveyer can be made of a material that allows water to be removed while also capturing the resulting web of basalt fibers and resin powder, for instance, a wire-net belt or a fabric material. The moisture of the slurry can be removed by vacuum suction to form a web of the basalt fibers and resin powder. The web can then pass through a heating furnace to drive off more moisture and also to cause the resin powder to melt.
[0046] Films, such as, an air-impermeable film or an adhesive film, can be laminated by a nip roller onto one or both sides of the web. Passing through the nip roller results in the crushing of the web and the fixing of the basalt fibers in the resin binder. In some cases, the thickness of the web after passing through the nip roller can be about 3 mm. The web can become a hard or resilient sheet due to cooling and setting of the resin, which cooling can be enhanced by optional blowing of air across the web.
[0047] In the present method, in the web forming step, the basalt fibers can become biased in a fallen state by the force of either or both of the vacuum suction through the wire-net belt or the roll pressure of the nip roller, and can become fixed by the resin binder in that state. Thus, the basalt fibers, in this fixed fallen state, can have potential energy to return to a more expanded or relaxed state, and can return to that expanded state if released by the resin binder.
[0048] Further detailed description of the present teachings will be provided by referring to the drawings of some embodiments of a roof lining for a vehicle and a manufacturing method thereof.
[0049] In FIGS. 1 to 3 , a roof lining for a vehicle 10 has a surface skin layer 30 having pleasant tactile properties and appearance attached to a front face of a substrate 20 having shape retaining properties. On a backside of the substrate 20 , there can be a laminated structure having a backside nonwoven fabric 40 provided for, in some embodiments, sound absorbency.
[0050] In some embodiments of the present roof lining, the substrate or blank 20 has a structure in which basalt fibers 21 are three-dimensionally intertwined and are fixed by a resin binder 22 . This configuration can be lightweight, have enhanced sound absorbency and heat insulating properties while also having suitable stiffness. The surface skin layer 30 can be a relatively heavy weight material, such as 130 g/m2 in the case of using a cloth such as tricot, jersey, moquette or knit, and 200 g/m2 in the case of a nonwoven fabric. Additionally, a hot-melt film 31 for enhancing adhesiveness can be placed between the substrate 20 and the surface skin layer 30 . The hot-melt film 31 can be laminated onto the substrate 20 during the production process, such as, during the pressing of the web into the blank.
[0051] According to the present teachings, suitable resins and resin mixtures that can be utilized in the process described above include propylene polymers, by which it is intended to include homopolymeric polypropylene and copolymers of propylene with other copolymerizable monomers wherein the major portion, that is, greater than about 50% by weight of the copolymer is comprised of propylene moieties. Suitable copolymerizable monomers include, for example, ethylene, butylene, 4-methyl-pentene-1, and the like.
[0052] The thermoplastic resins, for example, polypropylene resin, polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin and polycarbonate resin tend to have excellent characteristics such as the ability to be produced at comparatively low cost, and easy processability. According to the present teachings and among the above-exemplified resins and polymers, polypropylene resin is one preferred resin.
[0053] In one preferred embodiment of the present teachings, the surface skin layer 30 can be a tricot cloth of weight of about 130 g/m2 and a nylon film can be used as the hot-melt film 31 . The backside nonwoven fabric 40 can have a relatively light weight ranging between about 10 to 100 g/m2, and an air-impermeable polyamide resin can be used as film 41 and can be placed between the backside nonwoven fabric 40 and the basalt fiber and resin binder containing substrate 20 . As for the fiber of the backside nonwoven fabric 40 , a general-purpose synthetic resin fiber such as polyolefin, polyester or polyamide can be used.
[0054] In some embodiments of the present teachings, the air-impermeable film 41 can be composed of a suitable material such as a thermoplastic film. Suitable thermoplastics include, for instance, polyolefins, polyethylene, polypropylene, polyamides, and ethylene-propylene copolymer films as acceptable film materials. The air-impermeable film 41 can be water-proof, or can be substantially water-proof, or can be substantially water-resistant.
[0055] The substrate 20 composed of the basalt fiber-containing material can be of substantially uniform density throughout, that is, the substrate does not have a higher density skin or coating on its outer surface.
[0056] The areal density of the substrate can be a factor in achieving the desired balance between weight and performance, such as sound absorbency and stiffness of the roof lining according to the present teachings. In some examples of the roof lining, it is desirable to have a substrate with an areal density ranging between about 600 to about 1200 g/m2. A concern in cases where the weight per square meters of the substrate is less than 600 g m2, can be that the stiffness of the part can be too low and handling can be difficult. Conversely, when the areal density of the substrate exceeds 1200 g/m2, curtain airbags which can be placed inside the roof lining can have difficulty in operating correctly. In some embodiments of the present roof lining, the areal density of the substrate 20 can be 900 g/m2 with a specific gravity of about 0.33.
[0057] FIG. 4 illustrates one embodiment of the process of the present teachings. The basalt fibers 21 and the PP resin binder powder 22 are each contained in dedicated hoppers 50 and 51 respectively. The basalt fibers 21 and the PP resin binder powder 22 are transferred into a mixing container 52 from the hoppers 50 and 51 . Water can be initially present in the mixing container 52 , where the basalt fibers 21 , the PP resin powder 22 and water are stirred to obtain a slurry. In some embodiments of the present process, water can be added to the mixing container 52 after one or both of the basalt fibers 21 and the PP resin powder 22 have been added to the mixing container 52 .
[0058] A headbox 54 and the initial end of a wire-net belt conveyer 53 circulatively driven at a predetermined speed by a pulley 53 a are positioned below the mixing container 52 . The slurry is transferred from the mixing container 52 to the headbox 54 . The slurry is then spread from the headbox 54 across the wire-net belt conveyer 53 . A vacuum suction mechanism 55 positioned below the wire-net belt conveyer 53 removes water to form a web W consisting of the basalt fibers 21 and the PP resin powder 22 . Any additional moisture remaining in the web W is evaporated by a heating furnace 56 . The heating furnace 56 also causes the PP resin powder 22 to melt.
[0059] As shown in FIG. 5 , an air-impermeable film 41 and a nonwoven fabric 40 are laminated by a nip roller 57 on the back face side of the web W to form a blank M. On the front face side of the web W, a hot-melt film 31 is laminated for later adhesion with a surface skin layer 30 . The nip roller 57 crushes and adjusts the thickness of the blank to approximately 3 mm, and also fixes the basalt fibers 21 in the molten or softened PP resin binder 22 .
[0060] The blank M is then cut to a predetermined size by a width cutter 58 and a length cutter 59 , and piled on a palette 60 . As shown in FIG. 6 , the blank M in this state has the basalt fibers 21 fixed on the PP resin binder 22 . In particular, this is the state where the basalt fibers 21 are fixed in a biased flattened direction.
[0061] As shown in FIG. 7 , the blank M is heated and softened at a predetermined temperature by a suitable heating source, here, for example, an infrared heating furnace 70 . In certain embodiments of the present teachings, the blank M is heated to the melting point temperature of the resin binder, such as, in the range of 170 to 230° C. As shown, the several of the edges of the blank M are held by clamps 71 . In this heated condition, the resin binder 22 melts and the pressure previously applied to the basalt fibers 21 by the nip rollers 57 is eliminated so that the basalt fibers 21 rise and are restored as shown in FIG. 8 .
[0062] As shown in FIG. 9 , the blank M, with any adhesive film facing toward the surface skin layer 30 , and the surface skin layer 30 are aligned and set in a cold press forming die assembly 80 which consists of upper die 81 and lower die 82 . Thereafter, as shown in FIG. 10 , the upper die 81 is lowered by a predetermined stroke so as to form the substrate 20 having a form matching with the roof panel by clamping of the upper die 81 and lower die 82 , and also to adhere the surface skin layer 30 to the substrate 20 . In some embodiments of the process, one or both or the upper and lower dies can be moved to form the substrate 20 . For various embodiments of the present roof lining, the roof lining is formed into the desired shape by the die assembly, with clamping forces of 50 ton and a press pressure of 1 to 3 kg/cm2. The cold press is then opened, and the formed roof lining is removed. The roof lining can undergo further processing to produce a final roof lining for a vehicle 10 as shown in FIG. 1 .
[0063] All publications, articles, papers, patents, patent publications, and other references cited herein are hereby incorporated herein in their entireties for all purposes.
[0064] Although the foregoing description is directed to the preferred embodiments of the present teachings, it is noted that other variations and modifications will be apparent to those skilled in the art, and which may be made without departing from the spirit or scope of the present teachings.
[0065] The foregoing detailed description of the various embodiments of the present teachings has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present teachings to the precise embodiments disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiments were chosen and described in order to best explain the principles of the present teachings and their practical application, thereby enabling others skilled in the art to understand the present teachings for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the present teachings be defined by the following claims and their equivalents.
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The present disclosure is directed to a roof lining for a vehicle and a manufacturing method thereof, and in particular, to the roof lining for a vehicle using a composite material having basalt fibers mixed into a thermoplastic resin as a substrate. The resulting roof lining can be lightweight, have enhanced sound absorbency and increased heat insulating properties. Due to the use of basalt fibers, which do not coat incinerator walls like glass fibers do, the roof lining is more easily recycled.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is a Continuation-in-Part application of U.S. application Ser. No. 08/351,006, filed Dec. 7, 1994, now abandoned, which is a Continuation-in-Part application of U.S. application Ser. No. 08/328,552, filed Oct. 24, 1994, now abandoned, which is a Continuation application of U.S. application Ser. No. 08/031,164, filed Mar. 12, 1993, abandoned, which is a Continuation-in-Part application of U.S. application Ser. Nos. 07/618,419 and 07/798,919, filed Nov. 27, 1990, and Nov. 27, 1991, respectively, both of which are abandoned, all of which are herein incorporated by reference.
RIGHTS OF THE UNITED STATES GOVERNMENT IN THIS INVENTION
Under a Cooperative Research and Development Agreement between The American National Red Cross and The U.S. Army Institute of Dental Research, the U.S. Government may have a non-exclusive, irrevocable, paid-up license in one or more embodiments of this invention.
FIELD OF INVENTION
This invention is directed to unsupplemented and supplemented Tissue Sealants (TSs), such as fibrin glue (FG), as well as to methods of their production and use. In one embodiment, this invention is directed to TSs which do not inhibit full-thickness skin wound healing. In another embodiment, this invention is directed to TSs which have been supplemented with a growth factor(s) and/or a drug(s), as well as to methods of their production and use. The particular growth factor(s) or drug(s) that is selected is a function of its use.
BACKGROUND OF THE INVENTION
A. Wound Healing and Growth Factors
Wound healing, the repair of lesions, begins almost instantly after injury. It requires the successive coordinated function of a variety of cells and the close regulation of degradative and regenerative steps. The proliferation, differentiation and migration of cells are important biological processes which underlie wound healing, which also involves fibrin clot formation, resorption of the clot, tissue remodeling, such as fibrosis, endothelialization and epithelialization. Wound healing involves the formation of highly vascularized tissue that contains numerous capillaries, many active fibroblasts, and abundant collagen fibrils, but not the formation of specialized skin structures.
The process of wound healing can be initiated by thromboplastin which flows out of injured cells. Thromboplastin contacts plasma factor VII to form factor X activator, which then, with factor V and in a complex with phospholipids and calcium, converts prothrombin into thrombin. Thrombin catalyzes the release of fibrinopeptides A and B from fibrinogen to produce fibrin monomers (viz. fibrin I and fibrin II), which aggregate to form fibrin filaments. Thrombin also activates the transglutaminase, factor XIIIa, which catalyzes the formation of isopeptide bonds to covalently cross-link the fibrin filaments. Alpha 2 -antiplasmin is then bound by factor XIII onto the fibrin filaments to thereby protect the filaments from degradation by plasmin (see, for example, Doolittle et al., Ann. Rev. Biochem. 53:195–229 (1984)).
When a tissue is injured, polypeptide growth factors, which exhibit an array of biological activities, are released into the wound where they play a crucial role in healing (see, e.g., Hormonal Proteins and Peptides (Li, C. H., ed.) Volume 7, Academic Press, Inc., New York, N.Y. pp. 231–277 (1979) and Brunt et al., Biotechnology 6:25–30 (1988)). These activities include recruiting cells, such as leukocytes and fibroblasts, into the injured area, and inducing cell proliferation and differentiation. Growth factors that may participate in wound healing include, but are not limited to: platelet-derived growth factors (PDGFs); insulin-binding growth factor-1 (IGF-1); insulin-binding growth factor-2 (IGF-2); epidermal growth factor (EGF); transforming growth factor-α (TGF-α); transforming growth factor-β (TGF-β); platelet factor 4 (PF-4); and heparin binding growth factors one and two (HBGF-1 and HBGF-2, respectively).
PDGFs are stored in the alpha granules of circulating platelets and are released at wound sites during blood clotting (see, e.g., Lynch et al., J. Clin. Invest. 84:640–646 (1989)). PDGFs include: PDGF; platelet derived angiogenesis factor (PDAF); TGF-β; and PF-4, which is a chemoattractant for neutrophils (Knighton et al., in Growth Factors and Other Aspects of Wound Healing: Biological and Clinical Implications , Alan R. Liss, Inc., New York, N.Y., pp. 319–329 (1988)). PDGF is a mitogen, chemoattractant and a stimulator of protein synthesis in cells of mesenchymal origin, including fibroblasts and smooth muscle cells. PDGF is also a nonmitogenic chemoattractant for endothelial cells (see, for example, Adelmann-Grill et al., Eur. J. Cell Biol. 51:322–326 (1990)).
IGF-1 acts in combination with PDGF to promote mitogenesis and protein synthesis in mesenchymal cells in culture. Application of either PDGF or IGF-1 alone to skin wounds does not enhance healing, but application of both factors together appears to promote connective tissue and epithelial tissue growth (Lynch et al., Proc. Natl. Acad. Sci. 76:1279–1283 (1987)).
TGF-β is a chemoattractant for macrophages and monocytes. Depending upon the presence or absence of other growth factors, TGF-β may stimulate or inhibit the growth of many cell types. For example, when applied in vivo, TGF-β increases the tensile strength of healing dermal wounds. TGF-β also inhibits endothelial cell mitosis, and stimulates collagen and glycosaminoglycan synthesis by fibroblasts.
Other growth factors, such as EGF, TGF-α, the HBGFs and osteogenin are also important in wound healing. EGF, which is found in gastric secretions and saliva, and TGF-α, which is made by both normal and transformed cells, are structurally related and may recognize the same receptors. These receptors mediate proliferation of epithelial cells. Both factors accelerate reepithelialization of skin wounds. Exogenous EGF promotes wound healing by stimulating the proliferation of keratinocytes and dermal fibroblasts (Nanney et al., J. Invest. Dermatol. 83:385–393 (1984) and Coffey et al., Nature 328:817–820 (1987)). Topical application of EGF accelerates the rate of healing of partial thickness wounds in humans (Schultz et al., Science 235:350–352 (1987)). Osteogenin, which has been purified from demineralized bone, appears to promote bone growth (see, e.g., Luyten et al., J. Biol. Chem. 264:13377 (1989)). In addition, platelet-derived wound healing formula, a platelet extract which is in the form of a salve or ointment for topical application, has been described (see, e.g., Knighton et al., Ann. Surg. 204:322–330 (1986)).
The Heparin Binding Growth Factors (HBGFs), also known as Fibroblast Growth Factors (FGFs), which include acidic HBGF (aHBGF also known as HBFG-1 or FGF-1) and basic HBGF (bHBGF also known as HBGF-2 or FGF-2), are potent mitogens for cells of mesodermal and neuroectodermal lineages, including endothelial cells (see, e.g., Burgess et al., Ann. Rev. Biochem. 58:575–606 (1989)). In addition, HBGF-1 is chemotactic for endothelial cells and astroglial cells. Both HBGF-1 and HBGF-2 bind to heparin, which protects them from proteolytic degradation. The array of biological activities exhibited by the HBGFs suggests that they play an important role in wound healing.
Basic fibroblast growth factor (FGF-2) is a potent stimulator of angiogenesis and the migration and proliferation of fibroblasts (see, for example, Gospodarowicz et al., Mol. Cell. Endocinol. 46:187–204 (1986) and Gospodarowicz et al., Endo. Rev. 8:95–114 (1985)). Acidic fibroblast growth factor (FGF-1) has been shown to be a potent angiogenic factor for endothelial cells (Burgess et al., supra, 1989). However, it has not been established if any FGF growth factor is chemotactic for fibroblasts.
Growth factors are, therefore, potentially useful for specifically promoting wound healing and tissue repair. However, their use to promote wound healing has yielded inconsistent results (see, e.g., Carter et al., in Growth Factors and Other Aspects of Wound Healing: Biological and Clinical Implications , Alan R. Liss, Inc., New York, N.Y., pp. 303–317 (1988)). For example, PDGF, IGF-1, EGF, TGF-α, TGF-β and FGF (also known as HBGF) applied separately to standardized skin wounds in swine had little effect on the regeneration of connective tissue or epithelium in the wounds (Lynch et al., J. Clin. Invest. 84:640–646 (1989)). Of the factors tested, TGF-β stimulated the greatest response alone. However, a combination of factors, such as PDGF-bb homodimer and IGF-1 or TGF-α produced a dramatic increase in connective tissue regeneration and epithelialization. (Id.) Tsuboi et al. have reported that the daily application of bFGF to an open wound stimulated wound healing in healing-impaired mice but not in normal mice ( J. Exp. Med. 172:245–251 (1990)). On the other hand, the application to human skin wounds of crude preparations of porcine or bovine platelet lysate, which presumably contained growth factors, increased the rate at which the wounds closed, the number of cells in the healing area, the growth of blood vessels, the total rate of collagen deposition and the strength of the scar tissue (Carter et al., supra).
The reasons for such inconsistent results are not known, but might be the result of difficulty in applying growth factors to a wound in a manner in which they can exhibit their normal array of biological activities. For example, it appears that some growth factor receptors must be occupied for at least 12 hours to produce a maximal biologic effect (Presta et al., Cell Regul. 2:719–726 (1991) and Rusnati et al., J. Cell Physiol. 154:152–161 (1993)). Because of such inconsistent results, the role played by exogenously applied growth factors in stimulating wound healing is not clear. Further, a means by which growth factors might be applied to wounds to produce prolonged contact between the wound and the growth factor(s) is not presently known.
B. TSs
Surgical adhesives and TSs which contain plasma proteins are used for sealing internal and external wounds, such as in bones and skin, to reduce blood loss and maintain hemostasis. Such TSs contain blood clotting factors and other blood proteins. FG, also called fibrin sealant, is a gel similar to a natural clot which is prepared from plasma. The precise components of each FG are a function of the particular plasma fraction which is used as a starting material. Fractionation of plasma components can be effected by standard protein purification methods, such as ethanol, polyethylene glycol, and ammonium sulfate precipitation, ion exchange, and gel filtration chromatography. Typically FG contains a mixture of proteins including traces of albumin, fibronectin and plasminogen. In Canada, Europe and possibly elsewhere, commercially available FG typically also contains aprotinin as a stabilizer.
FGs generally are prepared from: (1) a fibrinogen concentrate, which contains fibronectin, Factor XIII, and von Willebrand factor; (2) dried human or bovine thrombin; and (3) calcium ions. Commercially prepared FGs generally contain bovine components. The fibrinogen concentrate can be prepared from plasma by cryoprecipitation followed by fractionation, to yield a composition that forms a sealant or clot upon mixture with thrombin and an activator of thrombin such as calcium ions. The fibrinogen and thrombin concentrates are prepared in lyophilized form and are mixed with a solution of calcium chloride immediately prior to use. Upon mixing, the components are applied to a tissue where they coagulate on the tissue surface and form a clot that includes cross-linked fibrin. Factor XIII, which is present in the fibrinogen concentrate, catalyzes the cross-linking.
Australian Patent 75097/87 describes a one-component adhesive, which contains an aqueous solution of fibrinogen, factor XIII, a thrombin inhibitor, such as antithrombin III, prothrombin factors, calcium ions, and, if necessary, a plasmin inhibitor. Stroetmann, U.S. Pat. Nos. 4,427,650 and 4,427,651, describes the preparation of an enriched plasma derivative in the form of a powder or sprayable preparation for enhanced wound closure and healing that contains fibrinogen, thrombin and/or prothrombin, and a fibrinolysis inhibitor, and may also contain other ingredients, such as a platelet extract. Rose et al., U.S. Pat. Nos. 4,627,879 and 4,928,603, disclose methods for preparing cryoprecipitated suspensions that contain fibrinogen and Factor XIII and their use to prepare a FG. JP 1-99565 discloses a kit for the preparation of fibrin adhesives for wound healing. Alterbaum (U.S. Pat. No. 4,714,457) and Morse et al. (U.S. Pat. No. 5,030,215) disclose methods to produce autologous FG. In addition, improved FG delivery systems have been disclosed elsewhere (Miller et al., U.S. Pat. No. 4,932,942 and Morse et al., PCT Application WO 91/09641).
IMMUNO AG (Vienna, Austria) and BEHRINGWERKE AG (Germany) (Gibble et al., Transfusion 30:741–747 (1990)) presently have FGs on the market in Europe and elsewhere (see, e.g., U.S. Pat. Nos. 4,377,572 and 4,298,598, which are owned by IMMUNO AG). TSs are not commercially available in the U.S. However, the American National Red Cross and BAXTER/HYLAND (Los Angeles, Calif.) have recently co-developed a FG (ARC/BH FG) which is now in clinical studies.
The TSs which are used clinically outside of the U.S. pose certain clinical risks and have not been approved by the Food and Drug Administration for use in the USA. For example, the TSs available in Europe contain proteins of non-human origin such as aprotinin and bovine thrombin. Since these proteins are of non-human origin, people may develop allergic reactions to them. In Europe heat inactivation is used to inactivate viruses which may be present in the components of the FG. However, this heat inactivation method may produce denatured proteins in the FG which may also be allergenic. In addition, there is concern that this inactivation method will not inactivate prions which cause bovine spongiform encephalopathy, “mad cow disease,” which may be present in the TS due to the use of bovine proteins therein. Since this disease appears to have already crossed from sheep, in which it is called “scrapies,” to cows, it is not an insignificant concern that it could infect humans.
The ARC/BH FG has advantages over the TSs available in Europe because it does not contain bovine proteins. For example, the ARC/BH TS contains human thrombin instead of bovine thrombin and does not contain aprotinin. Since the ARC/BH FG does not contain bovine proteins it should be less allergenic in humans than those TSs available in Europe. In addition, the ARC/BH FG is virally inactivated by a solvent detergent method which produces fewer denatured proteins and thus is less allergenic than those available in Europe. Therefore, the ARC/BH FG possesses advantages over the TSs which are now commercially available in other countries.
FG is primarily formulated for clinical topical application and is used to control bleeding, maintain hemostasis and promote wound healing. The clinical uses of FG have recently been reviewed (Gibble et al., Transfusion 30:741–747 (1990); Lerner et al., J. Surg. Res. 48:165–181 (1990)). By sealing tissues FG prevents air or fluid leaks, induces hemostasis, and may contribute to wound healing indirectly by reducing or preventing events which may interfere with wound healing such as bleeding, hematomas, infections, etc. Although FG maintains hemostasis and reduces blood loss, it has not yet been shown to possess true wound healing properties. Because FG is suitable for both internal and external injuries, such as bone and skin injuries, and is useful to maintain hemostasis, it is desirable to enhance its wound healing properties.
FG with a fibrinogen concentration of approximately 39 g/l and a thrombin concentration of 200–600 U/ml has produced clots with significantly increased stress, energy absorption and elasticity values (Byrne et al., Br. J. Surg. 78:841–843 (1991)). Perforated Teflon cylinders filled with fibrin clot (5 mg/ml) and implanted subcutaneously stimulated the formation of granulation tissue, including an increased precipitation of collagen, when compared to empty cylinders (Hedelin et al., Eur. Surg. Res. 15:312 (1983)).
C. Bone Wounds and their Repair
The sequence of bone induction was first described by Urist et al. using demineralized cortical bone matrix ( Clin. Orthop. Rel. Res. 71:271 (1970) and Proc. Natl. Acad. Sci. USA 70:3511 (1973)). Implanted subcutaneously in allogeneic recipients, demineralized cortical bone matrix releases factors which act as local mitogens to stimulate the proliferation of mesenchymal cells (Rath et al., Nature ( Lond .) 278:855 (1979)). New bone formation occurs between 12 and 18 days postimplantation. Ossicle development replete with hematopoietic marrow lineage occurred by day 21 (Reddi, A., In Extracellular Matrix Biochemistry (Piez et al., ed.) Elsevier, New York, N.Y., pp. 375–412 (1984)).
Demineralized bone matrix (DBM) is a source of osteoinductive proteins known as bone morphogenetic proteins (BMP), and growth factors which modulate the proliferation of progenitor bone cells (see, e.g., Hauschka et al., J. Biol. Chem. 261:12665–12674 (1986) and Canalis et al., J. Clin. Invest. 81:277–281 (1988)). Eight BMPs have now been identified and are abbreviated BMP-1 through BMP-8. BMP-3 and BMP-7 are also known as osteogenin and osteogenic protein-1 (OP-1), respectively.
Unfortunately, DBM materials have little clinical use unless combined with particulate marrow autografts. There is a limit to the quantity of DBM that can be surgically placed into a recipient's bone to produce a therapeutic effect. In addition, resorption has been reported to be at least 49% (Toriumi et al., Arch. Otolaryngo. Head Neck Surg. 116:676–680 (1990)).
DBM powder and osteogenin may be washed away by tissue fluids before their osteoinductive potential is expressed. In addition, seepage of tissue fluids into DBM-packed bone cavities or soft-tissue collapse into the wound bed are two factors that may significantly affect the osteoinductive properties of DBM and osteogenin. Soft-tissue collapse into the wound bed may likewise inhibit the proper migration of osteocompetent stem cells into the wound bed.
Human DBM in powder form is currently used by American dentists to pack jaw bone cavities created during oral surgery. However, DBM in powder form is difficult to use.
Purified BMPs have osteoinductive effects in animals when delivered by a variety of means including FG (Hattori, T., Nippon. Seikeigeka. Gakkai. Zasshi. 64:824–834 (1990); Kawamura et al., Clin. Orthop. Rel. Res. 235:302–310 (1988); Schlag et al., Clin. Orthop. Rel. Res. 227:269–285 (1988) and Schwarz et al., Clin. Orthop. Rel. Res. 238:282–287 (1989)) and whole blood clots (Wang et al., J. Cell. Biochem. 15F:Q20 Abstract (1990)). However, Schwarz et al. (supra.) demonstrated neither a clear positive or negative effect of FG on ectopic osteoinduction or BMP-dependent osteoregeneration. Kawamura et al. (supra.) found a synergistic effect when partially purified BMP in FG was tested in an ectopic non-bony site. Therefore, these results are inconsistent and confusing.
TS also can serve as a “scaffold” which cells can use to move into a wounded area to generate new tissues. However, commercially available preparations of FG and other TSs are too dense to allow cell migration into and through them. This limits their effectiveness in some in vivo uses.
In one type of bone wound, called bone nonunion defects, there is a minimal gap above which no new bone formation occurs naturally. Clinically, the treatment for these situations is bone grafting. However, the source of bone autografts is usually limited and the use of allogeneic bones involves a high risk of viral contamination. Because of this situation, the use of demineralized, virally inactivated bone powder is an attractive solution.
D. Vascular Prostheses
Artificial vascular prostheses are frequently made out of polytetrafluoroethylene (PTFE) and are used to replace diseased blood vessels in humans and other animals. To maximize patency rates and minimize the thrombogenicity of vascular prostheses various techniques have been used including seeding of nonautologous endothelial cells onto the prothesis. Various substrates which adhere both to the vascular graft and endothelial cells have been investigated as an intermediate substrate to increase endothelial cell seeding. These substrates include preclotted blood (Herring et al., Surgery 84:498–504 (1978)), FG (Rosenman et al., J. Vasc. Surg. 2:778–784 (1985); Schrenk et al., Thorac. Cardiovasc. Surg. 35:6–10 (1986); Köveker et al., Thorac. Cardiovasc. Surgeon 34: 49–51 (1986) and Zilla et al., Surgery 105:515–522 (1989)), fibronectin (see, e.g., Kesler et al., J. Vasc. Surg. 3:58–64 (1986); Macarak et al., J. Cell Physiol. 116:76–86 (1983) and Ramalanjeona et al., J. Vasc. Surg. 3:264–272 (1986)), or collagen (Williams et al., J. Surg. Res. 38:618–629 (1985)). However, one general problem with these techniques is that nonautologous cells were used for the seeding (see, e.g., Schrenk et al., supra) thus raising the possibility of tissue rejection. In addition, a confluent endothelium is usually never established and requires months to do so if it is. As a result of this delay, there is a high occlusion rate of vascular prostheses (see, e.g., Zilla et al., supra).
E. Angiogenesis
Angiogenesis is the induction of new blood vessels. Certain growth factors such as HBGF-1 and HBGF-2 are angiogenic. However, their in vivo administration attached to: collagen sponges (Thompson et al., Science 241:1349–1352 (1988)); beads (Hayek et al., Biochem. Biophys. Res. Commun. 147:876–880 (1987)); solid PTFE fibers coated with collagen arranged in a sponge-like structure (Thompson et al., Proc. Natl. Acad. Sci. USA 86:7928–7932 (1989)); or by infusion (Puumala et al., Brain Res. 534:283–286 (1990)) resulted in the generation of random, disorganized blood vessels. These growth factors have not been used successfully to direct the growth of a new blood vessel(s) at a given site in vivo. In addition, fibrin gels (0.5–10 mg/ml) implanted subcutaneously in plexiglass chambers induce angiogenesis within 4 days of implantation, compared to empty chambers, or chambers filled with sterile culture medium (Dvorak et al., Lab. Invest. 57:673 (1987)).
F. Site-Directed, Localized Drug Delivery
An efficacious, site-directed, drug delivery system is greatly needed in several areas of medicine. For example, localized drug delivery is needed in the treatment of local infections, such as in periodontitis, where the systemic administration of antimicrobial agents is ineffective. The problem after systemic administration usually lies in the low concentration of the antimicrobial agent which can be achieved at the target site. To raise the local concentration a systemic dose increase may be effective but also may produce toxicity, microbial resistance and drug incompatibility. To circumvent some of these problems, several alternative methods have been devised but none are ideal. For example, collagen and/or fibrinogen dispersed in an aqueous medium as an amorphous flowable mass, and a proteinaceous matrix composition which is capable of stable placement, have also been shown to locally deliver drugs (Luck et al., U.S. Reissue Patent 33,375; Luck et al., U.S. Pat. No. 4,978,332).
A variety of antibiotics (AB) have been reported to be released from FG, but only at relatively low concentrations and for relatively short periods of time ranging from a few hours to a few days (Kram et al., J. Surg. Res. 50:175–178 (1991)). Most of the ABs have been in freely water soluble forms and have been added into the TS while it was being prepared. However, the incorporation of tetracycline hydrochloride tetracycline hydrochloride (TET HCl) and other freely water soluble forms of ABs into FG has interfered with fibrin polymerization during the formation of the AB-supplemented FG (Schlag et al., Biomaterials 4:29–32 (1983)). This interference limited the amount and concentration of the TET HCl that could be achieved in the AB-FG mixture and appeared to be AB concentration dependent. The relatively short release time of the AB from the FG may reflect the relatively short life of the AB-supplemented TS or the form and/or quantity of the AB in the AB-TS.
G. Controlled Drug Release from TSs
For some clinical applications controlled, localized drug release is desirable. As discussed above, some drugs, especially ABs, have been incorporated into and been released from TSs such as FG. However, there is little or no control over the duration of the drug release which apparently is at least partially a reflection of the relatively short life of the drug-supplemented FG. Therefore, a means to stabilize FG and other TSs to allow for extended, localized drug release is desirable and needed, as are new techniques for the incorporation and extended release of other supplements from TS.
H. The Disclosed TS Preparations Provide Life-Saving Emergency Treatment for Trauma Wounds
Despite continued advances in trauma care, a significant percentage of the population, both military and civilian, suffer fatal or severe hemorrhage every year. An alarming number of fatalities are preventable since the occur in the presence of those who could achieve life-saving control of their wounds given adequate tools and training. The availability of the herein-disclosed TS satisfies the long-felt need for a advanced, easy-to-use, field-ready hemostatic preparation, to permit not only trained medical personnel, but even untrained individuals to rapidly reduce bleeding in trauma victims. Utilization of the disclosed TS preparations will result in a two-fold benefit: the reduction of trauma death, and the decreased demand upon the available blood supply.
The disclosed technology would also be available for the treatment of massed casualties in disaster situation. When severe natural or man-made disasters occur, local hospitals and clinics may be overwhelmed by the number of individuals requiring trauma care. Combined with the isolating effects of such disasters, the resulting demand for blood and blood products often exceeds the locally available supplies. In many cases, the demand upon the local medical personnel also exceeds the availed number of trained individuals. As a result, less seriously injured persons may be turned-away or given sub-optimal care. The availability of the easy-to-use, self-contained TS preparations disclosed below will permit local medical personnel and disaster relief workers to provide the injured with temporary treatment until definitive care becomes available. Moreover, the disclosed TS preparations will permit self-treatment in disaster victims, until medical assistance can be provided.
Often the only form of medical treatment that can be applied under such circumstances to prevent death due to blood loss is pressure dressings, tourniquets and pressure points. Unfortunately, however, each of these treatments requires continuous monitoring and attention. Since such attention is not always possible in emergency or disaster situations, there is a clear need in the art for a simple, fast-acting, first-aid treatment which can successfully control excessive blood loss.
The application of the disclosed TS preparations to the military is readily apparent, particularly in isolated battlefield situations. The single greatest cause of death on the battlefield is exsanguination, which until now has accounted for up to 50% of all combat casualties.
SUMMARY OF THE INVENTION
In one embodiment, this invention provides a composition of matter, comprising a TS, wherein the sealant does not inhibit full-thickness skin wound healing.
In another embodiment, this invention provides a composition of matter, comprising: a TS, wherein the total protein concentration of the sealant is less than 30 mg/ml.
In another embodiment, this invention provides a composition of matter comprising a supplemented TS wherein the total protein concentration is less than 30 mg/ml and the supplement is a growth factor(s) and/or a drug(s).
In another embodiment, this invention provides a composition of matter comprising a supplemented TS wherein the total protein concentration is greater than 30 mg/ml and the supplement is a growth factor(s) and/or a drug(s).
In another embodiment, this invention provides a composition of matter that promotes the directed migration of animal cells, comprising: a TS; and an effective concentration of at least one growth factor, wherein the concentration of the growth factor is effective in promoting the directed migration of the animal cells.
In another embodiment, the present invention provides a composition of matter that promotes wound healing, comprising: a TS; and an effective concentration of at least one growth factor, wherein the concentration is effective in promoting wound healing.
In another embodiment, the present invention provides a composition of matter that promotes the endothelialization of a vascular prosthesis, comprising: a TS; and an effective concentration of at least one growth factor, wherein the concentration is effective in promoting the endothelialization of a vascular prosthesis.
In another embodiment, the present invention provides a composition of matter that promotes the proliferation and/or differentiation of animal cells, comprising: a TS; and an effective concentration of at least one growth factor, wherein the concentration is effective in promoting proliferation and/or differentiation of animal cells.
In another embodiment, the present invention provides a composition of matter that promotes the localized delivery of at least one drug, comprising: a TS; and at least one drug.
In another embodiment, the present invention provides a composition of matter that promotes the localized delivery of at least one growth factor, comprising: a TS; and at least one growth factor.
In another embodiment, the present invention provides a process for promoting the healing of wounds, comprising applying to the wound, a composition that contains a TS and an effective concentration of at least one growth factor, wherein the concentration is effective to promote wound healing.
In another embodiment, the present invention provides a process for promoting the endothelialization of a vascular prosthesis, comprising applying to the vascular prosthesis a composition that contains a TS and an effective concentration of at least one growth factor, wherein the concentration is effective to promote the endothelialization of a vascular prothesis.
In another embodiment, the present invention provides a process for promoting the proliferation and/or differentiation of animal cells, comprising placing the cells in sufficient proximity to a TS which contains an effective concentration of at least one growth factor, wherein the concentration is effective in promoting the proliferation and/or differentiation of the cells.
In a further embodiment, the present invention provides a process for the localized delivery of at least one drug to a tissue, comprising applying to the tissue a TS which contains at least one drug.
In another embodiment, the present invention provides a process for the localized delivery of at least one growth factor to a tissue, comprising applying to the tissue a TS which contains at least one growth factor.
In another embodiment, this invention provides a process for producing the directed migration of animal cells, comprising: placing in sufficient proximity to the cells, a TS which contains an effective concentration of at least one growth factor, wherein the concentration is effective to produce the desired directed migration of said cells.
In another embodiment, this invention provides a simple to use, fast acting, field-ready fibrin bandage for applying a tissue sealing composition to wounded tissue in a patient, comprising an occlusive backing, affixed to which is a layer of dry materials comprising an effective amount, in combination, of (a) dry, virally-inactivated, purified fibrinogen, (b) dry, virally-inactivated, purified thrombin, and as necessary (c) effective amounts of calcium and/or Factor XIII to produce a tissue-sealing fibrin clot upon hydration.
In a further embodiment, this invention provides a method of treating wounded tissue in a patient by applying to said wound a fibrin bandage, comprising: (1) a occlusive backing, affixed to which is a layer of dry materials comprising an effective amount, in combination, of (a) dry, virally-inactivated, purified fibrinogen, (b) dry, virally-inactivated, purified thrombin, and as necessary (c) effective amounts of calcium and/or Factor XIII to produce a tissue-sealing fibrin clot upon hydration.
In yet another embodiment, this invention provides a simple to use, fast acting, field-ready fibrin dressing for treating wounded tissue in a patient, is formulated as an expandable foam comprising an effective amount, in combination, of (1) virally-inactivated, purified fibrinogen, (2) virally-inactivated, purified thrombin, and as necessary (3) calcium and/or Factor XIII; wherein said composition does not significantly inhibit full-thickness skin wound healing.
While in a further embodiment, this invention provides a method of treating wounded tissue in a patient by applying to said wound a tissue sealant expandable foam dressing, comprising an effective amount, in combination, of (1) virally-inactivated, purified fibrinogen, (2) virally-inactivated, purified thrombin, and as necessary (3) calcium and/or Factor XIII; wherein said composition does not significantly inhibit full-thickness skin wound healing.
In the embodiments of this invention, the TS may be FG.
In the various embodiments of the invention FG may be made from the mixing of topical fibrinogen complex (TFC), human thrombin and calcium chloride. Varying the concentration of the TFC has the most significant effect upon the density of the final FG matrix. Varying the concentration of the thrombin has an insignificant effect upon the total protein concentration of the final FG, but has a profound effect upon the time required for the polymerization of the fibrinogen component of the TFC into fibrin. While this effect is well known, it is not generally appreciated that it may be used to maximize the effectiveness of the FG, when it is used alone or supplemented. Because of this effect one can alter the time between the mixing of the FG components and the setting of the FG. Thus, one can allow the FG to flow more freely into deep crevices in a wound, permitting it to fill the wound completely before the FG sets. Alternatively, one can allow the FG to set quickly enough to prevent it from exiting the wound site, especially if the wound is leaking fluid under pressure (i.e., blood, lymph, intercellular fluid, etc). This property is also important to keep the FG from clogging delivery devices with long passages, i.e., catheters, endoscopes, etc., which is important to allow the application of the FG or supplemented FG to sites in the body that are only accessible by surgery. This effect is also important in keeping the insoluble supplements in suspension and preventing them from settling in the applicator or in the tissue site.
As used herein, TFC is a lyophilized mixture of human plasma proteins which have been purified and virally inactivated. When reconstituted TFC contains:
Total Protein:
100–130 mg/ml
Fibrinogen:
(as clottable protein) 80% of total protein
(minimum)
Albumin (Human):
5–25 mg/ml
Plasminogen:
5 mg/ml
Factor XIII:
10–40 Units/ml
Polysorbate-80:
0.3% (maximum)
pH:
7.1–7.5.
The reconstituted TFC may also contain trace amounts of fibronectin.
As used herein, human thrombin is a lyophilized mixture of human plasma proteins, which have been purified and virally inactivated. When reconstituted it contains:
Thrombin Potency:
300 ± 50 International Units/ml
Albumin (Human):
5 mg/ml
Glycine:
0.3 M ± .05 M
pH:
6.5–7.1.
Calcium chloride is added in sufficient concentration to activate the thrombin. As long as there is sufficient calcium, its concentration is not important.
In the compositions of this invention containing a growth factor, the composition may contain an inhibiting compound(s) and/or potentiating compound(s), wherein the inhibiting compound(s) inhibit the activities of the sealant that interfere with any of the biological activities of the growth factor, the potentiating compound(s) potentiate, mediate or enhance any of the biological activities of the growth factor, and wherein the concentration of the inhibiting or potentiating compound is effective for achieving the inhibition, potentiation, mediation or enhancement.
The growth factor-supplemented TSs of this invention are useful for promoting the healing of wounds, especially those that do not readily heal, such as skin ulcers in diabetic individuals, and for delivering growth factors including, but not limited to, FGF-1, FGF-2, FGF-4, PDGFs, EGFs, IGFs, PDGF-bb, BMP-1, BMP-2, OP-1, TGF-β, cartilage-inducing factor-A (CIF-A), cartilage-inducing factor-B (CIF-B), osteoid-inducing factor (OIF), angiogenin(s), endothelins, hepatocyte growth factor and keratinocyte growth factor, and providing a medium for prolonged contact between a wound site and the growth factor(s). The growth factor-supplemented TS may be used to treat burns and other skin wounds and may comprise a TS and, in addition to the growth factor(s), an antibiotic(s) and/or an analgesic(s), etc. The growth factor-supplemented TS may be used to aid in the engraftment of a natural or artificial graft, such as skin to a skin wound. They may also be used cosmetically, for example in hair transplants, where the TS might contain FGF, EGF, antibiotics and minoxidil, as well as other compounds. An additional cosmetic use for the compositions of this invention is to treat wrinkles and scars instead of using silicone or other compounds to do so. In this embodiment, for example, the TS may contain FGF-1, FGF-4, and/or PDGFs, and fat cells. The growth factor-supplemented TSs may be applied to surgical wounds, broken bones or gastric ulcers and other such internal wounds in order to promote healing thereof. The TSs of this invention may be used to aid the integration of a graft, whether artificial or natural, into an animal's body as for example when the graft is composed of natural tissue. The TSs of this invention can be used to combat some of the major problems associated with certain conditions such as periodontitis, namely persistent infection, bone resorption, loss of ligaments and premature re-epithelialization of the dental pocket.
In another embodiment, this invention provides a mixture of FG, DBM and/or purified BMP's. This mixture provides a matrix that allows the cellular components of the body to migrate into it and thus produce osteoinduction where needed. The matrix composition in terms of proteins (such as fibrinogen and Factor XIII), enzymes (such as thrombin and plasmin), BMPs, growth factors and DBM and their concentrations are adequately formulated to optimize the longevity of this temporal scaffolding structure and the osteoinduction which needs to occur. All the FG components are biodegradable but during osteogenesis the mixture provides a non-collapsible scaffold that can determine the shape and location of the newly formed bone. Soft tissue collapse into the bony nonunion defect, which is a problem in bone reconstructive surgery, will thus be avoided. The use of TS supplemented with growth factors such as CIF-A and CIF-B, infra, which promote cartilage development, will be useful in the reconstruction of lost or damaged cartilage and/or damaged bone.
In a preferred embodiment, an effective concentration of HBGF-1 is added to a FG in order to provide a growth factor-supplemented TS that possesses the ability to promote wound healing. In another preferred embodiment, an effective amount of a platelet-derived extract is added to a FG. In other preferred embodiments, an effective concentration of a mixture of at least two growth factors are added to FG and an effective amount of the growth factor(s)-supplemented FG is applied to the wounded tissue.
In addition to growth factors, drugs, polyclonal and monoclonal antibodies and other compounds, including, but not limited to, DBM and BMPs may be added to the TS. They accelerate wound healing, combat infection, neoplasia, and/or other disease processes, mediate or enhance the activity of the growth factor in the TS, and/or interfere with TS components which inhibit the activities of the growth factor in the TS. These drugs may include, but are not limited to: antibiotics, such as tetracycline and ciprofloxacin; antiproliferative/cytotoxic drugs, such as 5-fluorouracil (5-FU), taxol and/or taxotere; antivirals, such as gangcyclovir, zidovudine, amantidine, vidarabine, ribaravin, trifluridine, acyclovir, dideoxyuridine and antibodies to viral components or gene products; cytokines, such as α- or β- or γ-Interferon, α- or β-tumor necrosis factor, and interleukins; colony stimulating factors; erythropoietin; antifungals, such as diflucan, ketaconizole and nystatin; antiparasitic agents, such as pentamidine; anti-inflammatory agents, such as α-1-anti-trypsin and α-1-antichymotrypsin; steroids; anesthetics; analgesics; and hormones. Other compounds which may be added to the TS include, but are not limited to: vitamins and other nutritional supplements; hormones; glycoproteins; fibronectin; peptides and proteins; carbohydrates (both simple and/or complex); proteoglycans; antiangiogenins; antigens; oligonucleotides (sense and/or antisense DNA and/or RNA); BMPs; DBM; antibodies (for example, to infectious agents, tumors, drugs or hormones); and gene therapy reagents. Genetically altered cells and/or other cells may also be included in the TSs of this invention. The osteoinductive compounds which can be used in practicing this invention include, but are not limited to: osteogenin (BMP3); BMP-2; OP-1; BMP-2A, -2B, and -7; TGF-β, HBGF-1 and -2; and FGF-1 and -4. In addition, anything which does not destroy the TS can be added to the TSs of this invention.
The studies reported herein unexpectedly demonstrate that the inclusion of compounds such as the free base TET or ciprofloxacin (CIP) HCl, in FG or the treatment of FG therewith confers extended longevity to the supplemented FG. This phenomenon can be exploited to increase the duration of a drug's release from the TS. Alternatively, this phenomenon can be exploited to modulate the release of another drug(s) other than the compound used to stabilize the FG, which is (are) also incorporated into the TET-FG, and/or to cause the FG to persist for a greater period in vivo or in vitro.
In general, poorly water soluble forms of a drug, such as the free base of TET, increase the delivery of the drug from the TS more than freely water soluble forms thereof. Therefore, the drug may be bound to an insoluble carrier, such as fibrinogen or activated charcoal, within the TS to prolong the delivery of the drug from the supplemented TS.
In another embodiment, the supplemented TS can be used in organoids and could contain, for example, growth factors such as FGF-1, FGF-2, FGF-4 and OP-1.
In another embodiment, this invention provides a composition that promotes the localized delivery of a poorly water soluble form of an antibiotic(s), such as the free base form of TET, and other drug(s), comprising a TS and an effective concentration of at least one poorly water soluble form of an antibiotic. Similar delivery methods are also applied to other drugs, antibodies, oligonucleotides, cytotoxins, cell proliferation inhibitors, osteogenic or cartilage inducing compounds, growth factors or other supplements herein disclosed.
The present invention has several advantages over the previously used TS compositions and methods. The first advantage is that the growth factor- and/or drug-supplemented TSs of the present invention have many of the characteristics of an ideal biodegradable carrier, namely: they can be formulated to contain only human proteins thus eliminating or minimizing immunogenicity problems and foreign-body reactions; their administration is versatile; and their removal from the host's tissues is not required because they are degraded by the host's own natural fibrinolytic system.
A second advantage is that the present invention provides a good way to effectively deliver growth factors and/or drugs for a prolonged period of time to an internal or external wound. It appears that some growth factor receptors must be occupied for at least 12 hours to produce a maximal biological effect. Previously, there was no way to do this. The present invention allows for prolonged contact between the growth factor and its receptors to occur, and thus allows for the production of strong biological effects.
A third advantage of the present invention is that animal cells can migrate into and through, and grow in the TSs of the present invention. This aids engraftment of the cells to neighboring tissues and prostheses. Based on the composition of the TSs which are available in Europe, it is expected that this is not possible with these formulations. Instead, animal cells must migrate around or digest commercially available TS. Since the importation into the U.S. of commercially available TSs from Europe is illegal (their use in the USA has not been approved by the U.S. FDA).
A fourth advantage is that because of its initial liquid nature, the TS of the present invention can cover surfaces more thoroughly and completely than many previously available delivery systems. This is especially important for the use of the present invention in coating biomaterials and in the endothelialization of vascular prostheses because the growth factor-supplemented FG will coat the interior, exterior and pores of the vascular prosthesis. As a result of this, plus the ability of endothelial cells to migrate into and through the TS, engraftment of autologous endothelial cells will occur along the whole length of the vascular prosthesis, thereby decreasing its thrombogenicity and antigenicity. With previously used TSs, engraftment started at the ends of the vascular prosthesis and proceeded, if at all, into the interior of the same, thus allowing a longer period for thrombogenicity and antigenicity to develop. Previously used TSs for vascular prostheses also primarily were seeded with nonautologous cells which could be rejected by the body and could be easily washed off by the shearing force of blood passing through the prosthesis.
A fifth advantage is that the supplemented and unsupplemented TS of this invention can be molded and thus can be custom made into almost any desired shape. For example, TS such as FG can be supplemented with BMPs and/or DBM and can be custom made into the needed shape to most appropriately treat a bone wound. This cannot be done with DBM powder alone because DBM powder will not maintain its shape.
A sixth advantage is that the AB-supplemented FG of this invention, such as TET-FG, has unexpectedly increased the longevity and stability of the FG compared to that of the unsupplemented FG. This increased stability continues even after appreciable quantities of the AB are no longer remaining in the FG. For example, soaking a newly formed FG clot in a saturated solution of TET produced from free base TET, or in a solution of CIP HCl, produces a FG clot which is stable and preserved even after substantially all the TET or CIP has left the FG clot. While not wishing to be bound by any theory as to how this effect is, produced, it is believed that the AB, such as TET or CIP, inhibits plasminogen which is in the TFC and breaks down the FG. Once the plasminogen is inhibited, its continued inhibition does not appear to depend on appreciable quantities of the TET or CIP remaining in the FG. As a result of this stabilizing effect, one can expect an increased storage shelf life of the TS, and possibly an increased persistence in vivo.
The seventh advantage of the present invention is a direct result of the prolonged longevity and stability of the TS. As a result of this unexpected increase in stability of the TS, AB-supplemented FG can be used to produce localized, long term delivery of a drug(s) and/or a growth factor(s). This delivery will continue even after the stabilizing drug, such as TET or CIP, has substantially left the TS. Inclusion of a solid form, preferably a poorly water soluble form of a drug such as free base, into a TS that has been stabilized by, for example, TET or CIP, then allows the stabilized TS to deliver that drug (or growth factor) locally for an extended period of time. Some forms of drugs, such as free base TET, allow for both stabilization of the TS and for prolonged drug delivery. Other drugs may do one or the other but not both. A compound used for the stabilization of a TS to produce prolonged, localized drug delivery is not previously known in the art.
An eighth advantage of the present invention is that it allows site-directed angiogenesis to occur in vivo. While others have demonstrated localized non-specific angiogenesis, supra, no one else has used a TS to promote site-directed angiogenesis.
A ninth advantage of the present invention is that because the components of the TS can be formulated into several forms of simple to use, fast-acting field dressings, it is now possible to control bleeding from hemorrhaging trauma wounds, thereby saving numerous lives that previously would have been lost. Although life-saving methods of treating such wounds are possible by trained medical personal or in fully-equipped clinics and hospitals, the present invention satisfies society's long-felt need for an easy-to-use, first-aid (or even self-applied) treatment that will, in emergency or disaster situations, allow an untrained individual to treat traumatic injuries to control hemorrhage until medical assistance is available.
BRIEF DESCRIPTION OF THE FIGURES
FIGS. 1A–1F show Western blots of gels on which samples containing HBGF-1β had been incubated with 250 U/ml thrombin in the presence of increasing concentrations of heparin. Solutions containing HBGF-1β (10 μg/ml), thrombin (250 μg/ml), and increasing concentrations of heparin (0, 0.5, 5, 10, 20, and 50 units/ml) were incubated at 37° C. for 72 hours. Aliquots were periodically removed from each of the incubating mixtures and were loaded onto 8% SDS polyacrylamide gels that were prepared and run as described by Laemmli ( Nature 227:680 (1970)). The gel was then electroblotted onto nitrocellulose and the band corresponding to HBGF-1β was identified using an affinity-purified polyclonal rabbit antiserum to HBGF-1β.
The concentrations of heparin in the incubating mixtures were: panel A) 0 units/ml; panel B) 0.5 U/ml; Panel C) 5 U/ml; panel D) 10 U/ml; panel E) 20 U/ml; and panel F) 50 U/ml. In the gels pictured in each of panels A–F, each lane contains the following: lane 1 contains SDS-PAGE low molecular weight standards; lane 2 contains biotinylated standards; lane 3 contains 10 μg/ml HBGF-1β; lane 4 contains 250 U/ml thrombin; and lanes 5–13 contain samples removed from the incubating mixtures at times 0, 1, 2, 4, 6, 8, 24, 48, and 72 hours.
FIG. 2 . Graph showing the incorporation of 3 H-thymidine as a function of relative HBGF-1β concentration. Samples of the HBGF-1β were incubated, as described in FIG. 1 and Example 2, in the presence of 250 U/ml thrombin and 5 U/ml heparin for 0, 24 or 72 hours. Dilutions of these samples were then added to NIH 3T3 cells, which were plated as described in Example 3. CPM is plotted v. HBGF-1 concentration.
FIG. 3 . Photograph showing the typical pattern of human umbilical vein endothelial cells after 7 days' growth on FG supplemented with 100 ng/ml of active, wild-type FGF-1. Note the large number of cells and their elongated shape. Compare with the paucity of cell grown on unsupplemented FG ( FIG. 5 ).
FIG. 4 . Photograph showing the typical pattern of human umbilical vein endothelial cells after 7 days' growth on FG supplemented with 10 ng/ml of active, wild-type FGF-1. Note the large number of cells and their elongated shape. Compare with the paucity of cells grown on unsupplemented FG ( FIG. 5 ).
FIG. 5 . Photograph showing the typical pattern of human umbilical vein endothelial cells after 7 days' growth on unsupplemented FG. Note the small number of cells, compared to the number of cells in FIGS. 3 and 4 , which indicates a slower proliferation rate.
FIG. 6 . Photograph showing the typical pattern of human umbilical vein endothelial cells after 7 days' growth on FG supplemented with 100 ng/ml of inactive, mutant FGF-1. Note the small number of cells, compared to the number of cells in FIGS. 3 and 4 , which indicates a slower proliferation rate.
FIG. 7 . Photograph showing the typical pattern of human umbilical endothelial cells 24 hours after having been embedded in FG at a concentration of 10 5 cells per ml of FG. The protein and thrombin concentrations of the FG were 4 mg/ml and 0.6 NIH units/ml, respectively. Note, their elongated, multipodial morphology and that they formed a cellular network where they came in contact with each other. Compare with the cobblestone shape of similar cells grown in fibronectin ( FIG. 9 .)
FIG. 8 . Photograph showing the typical pattern of human umbilical endothelial cells 48 hours after having been embedded in FG at a concentration of 10 5 cells per ml of FG. The culture conditions were as described in FIG. 7 . Note the further accentuated, elongated and multipodial morphology and increasing development of cellular networks. Compare with the cobblestone shaped cells grown in fibronectin ( FIG. 10 ) and note the lack of a cellular network in the latter.
FIG. 9 . Photograph showing the typical pattern of human umbilical endothelial cells 24 hours after having been cultured on a surface coated with fibronectin. Note the cobblestone shape of the cells and the lack of cellular networks. Compare to FIG. 7 .
FIG. 10 . Photograph showing the typical pattern of human umbilical endothelial cells 48 hours after having been cultured in a commonly used film of fibronectin. Note the cobblestone shape of the cells and the lack of cellular networks. Compare to FIG. 8 .
FIG. 11 . Micrographs of cross sections of PTFE vascular grafts that were explanted from dogs after 7 days (panels A, C, E) or 28 days (panels B, D, F). Prior to implantation, the grafts were either untreated (A and B), coated with FG alone (C and D), or coated with FG supplemented with heparin and HBGF-1 (E and F).
Untreated controls (A & B) showed minimal mesenchymal tissue ingrowth, with both their interstices filled with, and their luminal surfaces coated with fibrin coagulum. The FG-treated grafts showed mesenchymal tissue ingrowth in only the outer half of the grafts' interstices, with the rest being filled with fibrin coagulum. Very few interstitial capillaries were present. In contrast, the grafts treated with FG containing FGF-1 showed more abundant interstitial ingrowth and by 28 days showed numerous capillaries, myofibroblasts and macrophages, with inner capsules consisting of several layers of myofibroblasts beneath confluent endothelial cell layers. Results of similar grafts after 128 days of implantation were similar, with greater numbers of capillaries in the FG+FGF-1 group (data not shown).
FIG. 12 . Scanning electron micrographs of the inner lining of the vascular grafts described in FIG. 11 after 28 days of implantation. The grafts were either untreated (G), coated with FG alone (H), or coated with FG supplemented with heparin and HBGF-1 (I). Untreated control grafts (G) showed sparse areas of endothelial cell coverage amidst areas of thrombus containing red blood cells, platelets, and areas of exposed PTFE graft material (visible in the center and top of the picture). Grafts coated with FG alone (H) showed islands of endothelial cells amidst areas of fibrin coagulum. In contrast, grafts treated with FG+HBGF-1 (I) showed confluent endothelial cells oriented along the direction of blood flow.
FIG. 13 . Graph showing the inhibition of smooth muscle cell proliferation by the release of tributyrin from supplemented fibrin sealant. Unsupplemented fibrin sealant=(□); tributyrin-supplemented fibrin sealant=(▪).
FIG. 14 . Diagram showing the preparation of disc-shape implants 1 mm thick and 8 mm in diameter prepared using an aluminum mold.
FIG. 15 . Diagram illustrating intramuscular bioassay for the induction of bone formation in rats by DBM alone, by FG implants or by DBM-FG.
FIG. 16 . Diagram illustrating the induction of bone formation in calvarial implants by DBM-FG.
FIG. 17 . Graph showing the radio-opacity data at 28 days postoperative from intramuscular implants of DBM-FG, DBM or FG.
FIG. 18 . Graph showing the radio-opacity data from DBM-FG (30 mg/ml) calvarial implants at 28 days, 3 months and 4 months postoperative.
FIG. 19 . FIG. 19A is a photograph of a craniotomy site at 28 days post surgery in a treated animal. FIG. 19B is a photograph of the calvarial wound from an untreated control at 28 days postoperative. Note that only fibrous connective tissue has developed across the craniotomy wound.
FIG. 20 . Photograph from the craniotomy wounds of animals which were treated with DBM particles only.
FIG. 21 . Photograph of new bone formed in the craniotomy site in response to DBM-FG (15 mg/ml).
FIG. 22 . Photograph of new bone formed in the craniotomy site in response to DBM-FG (15 mg/ml). Note that typically more bone marrow formed in craniotomy wounds that had been implanted with DBM-FG disks than with DBM implants alone.
FIG. 23 . Graph showing the release of TET from 3×6 mm diameter disks of FG at 37° C. The concentration of the released TET was measured spectrophotometrically in 2 ml of PBS supernatant that had been replaced daily. Two of these “static” in vitro experiments were carried out with identical results. The results of one of them is shown here.
FIG. 24 . Graph showing the release of TET from 3×6 mm diameter disks of FG at 37° C. The disks contained 100 mg/ml of TET and were placed in closed vessels filled with 2 ml of PBS. The TET concentration was measured spectrophotometrically in the PBS effluent which had been continuously exchanged at a rate of 3 ml/day. The volume of the PBS supernatant had been kept constant at approximately 2 ml. The data are the average of two experiments.
FIG. 25 . Graph showing the release of TET into saliva from 3×6 mm diameter disks containing 50 or 100 TET mg/ml FG at 37° C. The TET concentration was measured spectrophotometrically in 0.75 ml of saliva supernatant that had been replaced daily. The saliva used in these experiments had been pooled from ten donors, centrifuged, filtered and kept at 4° C.
FIG. 26 . Photograph showing the stability of TET-supplemented FG was increased compared to that of control FG. Photographs of 3×6 mm diameter FG matrices without TET and with 50 and 100 mg/ml TET over a period of 15 days. The disks had been kept in 0.75 ml of saliva which had been changed daily. The saliva had been pooled from 10 donors. It had then been centrifuged, filtered and stored at 4° C. before use in this experiment. Note that at nine days, the FG matrix which did not contain TET had decayed more than the matrices which contained either 50 or 100 mg/ml of TET Also note that at 15 days, the FG matrix which did not contain TET had almost totally decayed, whereas the FG matrices which contained 50 or 100 mg/ml of TET were almost unchanged. Therefore, the inclusion of 50 or 100 mg/ml of TET dramatically prolonged the longevity of FG matrices in saliva in vitro.
FIG. 27 . Graph showing the antibacterial activity of TET released from TET-supplemented FG. Two ml PBS surrounding the 3×6 mm TET-supplemented FG disks was replaced daily. For testing the antimicrobial activity of the released TET, 6 mm paper disks impregnated with the collected eluates were incubated for 18 hours at 37° C. on agar plates containing E. coli . Then the diameter of the zone of inhibition was measured.
FIG. 28 . Graph showing the release of ciprofloxacin, amoxicillin and metronidazole from FG matrices. Individual 3×6 mm diameter disks containing 100 mg/ml of the respective antibiotics were immersed in 2 ml of phosphate-buffered saline at 37° C. The supernatant was replaced daily and the antibiotic concentration was measured spectrophotometrically at 275, 274 and 320 nm, respectively.
FIG. 29 . Graph showing the release of TET from TET-supplemented FG disks was proportional to the temperature of the PBS bathing the TET-FG disks.
FIG. 30 . Graph showing the effect of FG protein concentration on the release of TET from TET-FG. Note that higher FG protein concentrations resulted in a slower TET release rate from the TET-FG.
FIG. 31A . Graph showing the elution profile of in vitro release of antibiotic from a supplemented fibrin sealant disks.
FIG. 31B . Graph showing the elution profile of in vitro vs. in vivo release of tetracycline from supplemented fibrin sealant disks.
FIG. 31C . Graph showing the inhibition of bacterial growth by tetracycline supplemented fibrin sealant disks as compared to unsupplemented fibrin sealant disks and culture media alone.
FIG. 32 . Graph showing the release of 5-FU from 5-FU-supplemented FG was prolonged by the use of solid forms of 5-FU.
FIG. 33 . Graph showing the effect over time of supernatants from taxol-supplemented fibrin sealant composition on rapidly proliferating human ovarian carcinoma cells. (OVCAR).
FIG. 34 . Graph showing the dose-response relationship of the chemotactic response of NIH 3T3 fibroblasts to Fibronectin. A step gradient of increasing concentrations of Fibronectin was added to the lower wells of the modified Boyden's chambers. The data are expressed as means+/−S.E. of migrated cells per high power field and demonstrate that, as a function of dose, fibronectin induced the chemotaxis of NIH 3T3 cells toward it.
FIG. 35 . Graph showing the dose-response of the chemotactic response of NIH 3T3 fibroblasts to FGF-1. A step gradient of increasing concentrations of FGF-1 was added to the lower wells of the modified Boyden's chambers in the presence of heparin. The data are expressed as the means+/−S.E. of migrated cells per high power field and demonstrate that, as a function of dose, FGF-1 induced the chemotaxis of fibroblasts toward it.
FIG. 36 . Graph showing the dose-response relationship of the chemotactic response of NIH 3T3 fibroblasts to FGF-2. A step gradient of increasing concentrations of FGF-2 was added to the lower wells of the modified Boyden's chambers. The data are expressed as the means+/−S.E. of migrated cells per high power field and demonstrate that, as a function of dose, FGF-2 induced the chemotaxis of fibroblasts toward it.
FIG. 37 . Graph showing the dose-response relationship of the chemotactic response of NIH 3T3 fibroblasts to FGF-4. A step gradient of increasing concentrations of FGF-4 was added to the lower wells of the modified Boyden's chambers in the presence of heparin. The data are expressed as the means+/−S.E. of migrated cells per high power field and demonstrate that, as a function of dose, FGF-4 induced the chemotaxis of fibroblasts toward it.
FIG. 38 . Graph showing the dose-response relationship of the chemotactic response of human dermal fibroblasts (HDFs) to FGF-1. A step gradient of increasing concentrations of FGF-1 was added to the lower wells of the modified Boyden's chambers in the presence of heparin. The data are expressed as the means+/−S.E. of migrated cells per high power field and demonstrate that, as a function of dose, FGF-1 induced the chemotaxis of HDFs toward it.
FIG. 39 . Graph showing the dose-response relationship of the chemotactic response of HDFs to FGF-2. A step gradient of increasing concentrations of FGF-2 was added to the lower wells of the modified Boyden's chambers. The data are expressed as the means+/−S.E. of migrated cells per high power field and demonstrate that, as a function of dose, FGF-2 induced the chemotaxis of HDFs toward it.
FIG. 40 . Graph showing the dose-response relationship of the chemotactic response of HDFs to FGF-4. A step gradient of increasing concentrations of FGF-4 was added to the lower wells of the modified Boyden's chambers. The data are expressed as the means+/−S.E. of migrated cells per high power field and demonstrate that, as a function of dose, FGF-4 induced the chemotaxis of HDFs toward it.
FIG. 41 . Graph showing the dose-response relationship of the chemotactic response of HDFs to FGF-4 in solution and in FG. FGF-4 was incorporated into FG and placed in the bottom well of chemotaxis chambers. The amount of FGF in the FG was sufficient to result in the indicated concentrations when evenly distributed throughout the FG and medium in the lower chamber. Negative controls included medium alone and FG without FGF. Medium containing FGF-4 at a concentration of 10 ng/ml in the lower chamber was utilized as a positive control. The data are expressed as the means+/−S.E. of migrated cells per high power field and demonstrate that, as a function of dose, FGF-4 released from FG induced the chemotaxis of HDFs toward the FG.
FIG. 42 . Diagram of a self-contained TS Wound Dressing.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Definitions
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. All patents and publications mentioned herein are incorporated by reference.
As used herein, a wound includes damage to any tissue in a living organism. The tissue may be an internal tissue, such as the stomach lining or a bone, or an external tissue, such as the skin. As such a wound may include, but is not limited to, a gastrointestinal tract ulcer, a broken bone, a neoplasia, and cut or abraided skin. A wound may be in a soft tissue, such as the spleen, or in a hard tissue, such as bone. The wound may have been caused by any agent, including traumatic injury, infection or surgical intervention.
As used herein, TS is a substance or composition that, upon application to a wound, seals the wound, thereby reducing blood loss and maintaining hemostasis. As used herein, FG is a composition, prepared from recombinant or plasma proteins, that upon application to a wound forms a clot, thereby sealing the wound, reducing blood loss and maintaining hemostasis. FG, supra, is a form of TS.
As used herein, supplemented TS includes any TS that, without substantial modification, can serve as a carrier vehicle for the delivery of a growth factor, drug or other compound, or mixtures thereof, and that, by virtue of its adhesive or adsorptive properties, can maintain contact with the site for a time sufficient for the supplemented TS to produce its desired effect, for example to promote wound healing.
As used herein, a growth factor-supplemented TS is a TS to which at least one growth factor has been added at a concentration that is effective for its stated purpose. The growth factor can, for example, accelerate, promote or improve wound healing, or tissue (re)generation. The growth factor-supplemented TSs may also contain additional components, including drugs, antibodies, anticoagulants and other compounds that: 1) potentiate, stimulate or mediate the biological activity of the growth factor(s) in the TS; 2) decrease the activities of components of the growth factor-supplemented TS which would inhibit or destroy the biological activities of the growth factor(s) in the sealant; or 3) allow prolonged delivery of the supplement from the TS; 4) possess other desirable properties.
As used herein, a potentiating compound is a compound that mediates or otherwise increases the biological activity of a growth factor in the TS. Heparin is an example of a compound that potentiates the biological activity of HBGF-1.
As used herein, an inhibiting compound is a compound that inhibits, interferes with, or otherwise destroys a deleterious activity of a component of the TS that would interfere with or inhibit the biological activity of a growth factor or factors in the TS. Inhibiting compounds may exert their effect by protecting the growth factor from degradation. An inhibiting compound does not, however, inhibit any activities that are essential for the desired properties, such as, for example, wound healing of the growth factor-supplemented TS. An example of an inhibiting compound is heparin.
As used herein, a growth factor includes any soluble factor that regulates or mediates cell proliferation, cell differentiation, tissue regeneration, cell attraction, wound repair and/or any developmental or proliferative process. The growth factor may be produced by any appropriate means including extraction from natural sources, production through synthetic chemistry, production through the use of recombinant DNA techniques and any other techniques, including virally inactivated, growth factor(s)-rich platelet releasate, which are known to those of skill in the art. The term growth factor is meant to include any precursors, mutants, derivatives, or other forms thereof which possess similar biological activity(ies), or a subset thereof, to those of the growth factor from which it is derived or otherwise related.
As used herein, HBGF-1, which is also known to those of skill in the art by alternative names, such as endothelial cell growth factor (ECGF) and FGF-1, refers to any biologically active form of HBGF-1, including HBGF-1β, which is the precursor of HBGF-1α and other truncated forms, such as FGF. U.S. Pat. No. 4,868,113 to Jaye et al., herein incorporated by reference, sets forth the amino acid sequences of each form of HBGF. HBGF-1 thus includes any biologically active peptide, including precursors, truncated or other modified forms, or mutants thereof that exhibit the biological activities, or a subset thereof, of HBGF-1.
Other growth factors may also be known to those of skill in the art by alternative nomenclature. Accordingly, reference herein to a particular growth factor by one name also includes any other names by which the factor is known to those of skill in the art and also includes any biologically active derivatives or precursors, truncated mutant, or otherwise modified forms thereof.
As used herein, biological activity refers to one or all of the activities that are associated with a particular growth factor in vivo and/or in vitro. Generally, a growth factor exhibits several activities, including mitogenic activity (the ability to induce or sustain cellular proliferation) and also non-mitogenic activities, including the ability to induce or sustain differentiation and/or development. In addition, growth factors are able to recruit or attract particular cells from which the proliferative and developmental processes proceed. For example, under appropriate conditions HBGF-1 can recruit endothelial cells and direct the formation of vessels therefrom. By virtue of this activity, growth factor-supplemented TS may thereby provide a means to enhance blood flow and nutrients to specific sites.
As used herein, extended longevity means at least a two fold increase in the visually observable, useful in vitro lifespan of a TS.
As used herein, demineralized bone matrix (DBM) means the organic matrix of bone that remains after bone is decalcified with hydrochloric or another acid.
As used herein, bone morphogenetic proteins (BMPs) mean a group of related proteins originally identified by their presence in bone-inductive extracts of DBM. At least 8 related members have been identified and are designated BMP-1 through BMP-8. The BMPs are also known by other names. BMP-2 is also known as BMP-2A. BMP-4 is also known as BMP-2B. BMP-3 is also known as osteogenin. BMP-6 is also known as Vgr-1. BMP-7 is also known as OP-1. Bone morphogenetic proteins is meant to include, but is not limited to BMP-1 through BMP-8.
As used herein, augmentation means using a supplemented or unsupplemented TS to change the internal or external surface contour of a component of an animal's body.
As used herein, a damaged bone is a bone which is broken, fractured, missing a portion thereof, or otherwise not healthy, normal bone.
As used herein, a deficient bone is a bone which has an inadequate shape or volume to perform its function.
As used herein, bone or DBM which is to be used to supplement a TS can be in the form of powder, suspension, strips or blocks or other forms as necessary to perform its desired function.
As used herein, organoid means a structure that may be composed of natural, artificial, or a combination of natural and artificial elements, that wholly or in part, replaces the function of a natural organ. An example would be an artificial pancreas consisting of a network of capillaries surrounded by cells transfected with an expression vector containing the gene for insulin. Such an organoid would function to release insulin into the bloodstream of a patient with Type I Diabetes.
Preparation of Supplemented TS
As a first step when practicing any of the embodiments of the invention disclosed herein, the supplement and TS must be selected. The supplement and TS may be prepared by methods known to those of skill in the art, may be purchased from a supplier thereof, or may be prepared according to the methods of this application. In a preferred embodiment, growth factor, drug- or DBM-supplemented FG is prepared.
In any of the embodiments of the present invention the supplement may be added to the fibrinogen, the thrombin, the calcium and/or the water component(s) before they are mixed to form the TS. Alternatively, the supplement(s) can be added to the components as they are being mixed to form the TS.
In embodiments of the present invention, the calcium and/or thrombin may be supplied endogenously from body fluids as, for example, those in a wound.
Preparation of TSs
In certain embodiments of this invention such as, but not limited to, vascular prostheses, and in bone and cartilage augmentation, TS which allows cells to migrate into and/or through it may preferably be used.
Any TS, such as commercially available FG, may be used in some embodiments of this invention. For example, FGs which are well known to those of skill in the art (see, e.g., U.S. Pat. Nos. 4,627,879; 4,377,572; and 4,298,598, all herein incorporated by reference) may be purchased from a supplier or manufacturer thereof, such as IMMUNO AG (Vienna, Austria) and BEHRINGWERKE AG (Germany). For these uses, such as localized drug delivery, the particular composition of the selected TS is not critical as long as it functions as desired. Commercially available FGs may be supplemented with growth factors, antibiotics and/or other drugs for use in the embodiments of this invention including, but not limited to: in vitro cellular proliferation and/or differentiation; drug delivery; growth factor delivery, etc.
For the experiments exemplified herein, FG was prepared from cryoprecipitate from fresh frozen plasma. The components of the FG that were used included: fibrinogen concentrate; thrombin; and calcium ions.
In a preferred embodiment of this invention, the total protein concentration in the prepared FG is from about 0.01 to 500 mg/ml of FG. In a more preferred embodiment, the total protein concentration in the prepared FG is from about 1 to 120 mg/ml FG. In the most preferred embodiment, the total protein concentration in the prepared FG is from about 4 to 30 mg/ml FG.
In a preferred embodiment of this invention, the fibrinogen concentration used to prepare the FG is from about 0.009 to 450 mg/ml of solution. In a more preferred embodiment, the fibrinogen concentration in this preparatory solution is from about 0.9 to 110 mg/ml. In the most preferred embodiment, the fibrinogen concentration in this preparatory solution is from about 3 to 30 mg/ml.
In a preferred embodiment, the thrombin concentration used to prepare the FG is 0.01–350 U/ml. In a more preferred embodiment, the thrombin concentration is 1–175 U/ml. In the most preferred embodiment, the thrombin concentration is 2–4 U/ml.
It is important that the calcium ion concentration be sufficient to allow for activation of the thrombin. In a preferred embodiment, the USP calcium chloride concentration is 0–100 mM. In a more preferred embodiment, the USP calcium chloride concentration is 1–40 mM. In the most preferred embodiment, the USP calcium chloride concentration is 2–4 mM. In some embodiments of this invention, the calcium may be supplied by the tissue or body fluids as, for example, in the wound dressing embodiment.
In preparing the TS, sterile water for injection should be used.
Although the concentration(s) of growth factor(s), drugs and other compounds will vary depending on the desired objective, the concentrations must be great enough to allow them to be effective to accomplish their stated purpose. In a preferred embodiment of this invention, the growth factor concentration is from about 1 ng/ml to 1 mg/ml of FG. In a more preferred embodiment, the growth factor concentration is from about 1 μg/ml to 100 μg/ml of FG. In the most preferred embodiment, the growth factor concentration is from about 5 μg/ml to 20 μg/ml of FG. In a preferred embodiment of this invention the TET or CIP concentration is from 0.01 to 300 mg/ml FG. In a more preferred embodiment of this invention the TET or CIP concentration is 0.01–200 mg/ml. In the most preferred embodiment of this invention the TET or CIP concentration is 1–150 mg/ml. The amount of the supplements to be added can be empirically determined by one of skill in the art by testing various concentrations and selecting that which is effective for the intended purpose and the site of application.
Preparation of Growth Factors
The growth factor(s), or mixture thereof, may be prepared by any method known to those of skill in the art or may be purchased commercially. Any growth factor may be selected including, but not limited to, for example, growth factors that stimulate the proliferation and/or attraction of certain cell types, such as endothelial cells, fibroblasts, epithelial cells, smooth muscle cells, hepatocytes, and keratinocytes, and/or growth factors which inhibit the growth of the same cell types and smooth muscle cells. Such selection may be dependent upon the particular tissue site for which the growth factor-supplemented TS will be applied and/or the type of effect desired. For example, an EGF-supplemented TS may be preferred for application to wounds in the eye and for treating gastric ulcers while an osteogenin-supplemented TS may be preferred for application to bone fractures and bone breaks in order to promote healing thereof.
In another preferred embodiment HBGF-1β was prepared and added to FG. HBGF-1β, or HBGF-1α, or any other active form of HBGF-1, can be purified from natural sources, from genetically engineered cells that express HBGF-1 or a derivative thereof, or by any method known to those of skill in the art.
HBGF-1β has been prepared using recombinant DNA methodology (Jaye et al., U.S. Pat. No. 4,868,113; Jaye et al., J. Biol. Chem. 262:16612–16617 (1987)). Briefly, DNA encoding HBGF-1β was cloned into a prokaryotic expression vector, a pUC9 derivative, and expressed intracellularly in E. coli . The expressed peptide was then released from the cells by pressure, using a cell disrupter operated on high compression-decompression cycles. After disruption, cell debris was removed by filtration and HBGF-1β was purified from the supernatant using standard methods of protein purification including affinity chromatography on heparin Sepharose™ followed by ion-exchange chromatography on CM-Sepharose™.
In addition to HBGF-1, described above, other growth factors that may be added to the FG include, but are not limited to, HBGF-2, IGF-1, EGF, TGF-β, TGF-α, any platelet-derived growth factor or extract, BMPs, and mixtures of any growth factors. For example, platelet-derived extracts, which serve as rich sources of growth factors, may be added to the TS in addition to or in place of other growth factors, such as HBGF-1.
In a preferred embodiment, a platelet-derived extract, prepared by any method known to those of skill in the art, is added to a TS. Such an extract has been prepared from plasma derived platelets for use with FG.
Platelet-Derived Wound Healing Factor (PDWHF) may be prepared and added to FG (Knighton et al., Ann. Surg. 204:322–330 (1986)). Briefly, to prepare PDWHF, blood is drawn into anticoagulant solution and platelet-rich plasma is prepared by refrigerated centrifugation. The platelets are isolated and stimulated with thrombin, which releases the contents of the alpha granule contents. The platelets are removed and an effective concentration of the remaining extract is added to a TS.
Additional Components of Growth Factor-Supplemented TS
Since they are essentially plasma fractions, the TSs contemplated for use with growth factors contain numerous components, some of which may interfere with the biological activity of the selected growth factor(s). For example, thrombin, which is an essential component of FG, can act as a proteolytic enzyme and specifically cleave HBGF-1β. Therefore, it may be necessary to include additional compounds, such as protease or other inhibitors, that protect the selected growth factor(s) from the action of other components in the TS which interfere with or destroy the biological activity of the growth factor(s).
Selection of the particular inhibiting compound(s) may be empirically determined by using methods, discussed below, that assess the biological activity of the growth factor(s) in the TS. Methods to assess biological activity are known to those of skill in the art.
In addition, in order for certain growth factors to exhibit their biological activities, it may be necessary to include compounds that potentiate or mediate the desired activity. For example, heparin potentiates the biological activity of HBGF-1 in vivo (see, e.g., Burgess et al., Annu. Rev. Biochem. 58:575–606 (1989)).
The supplemented TS of the present invention may contain compounds such as drugs, other chemicals, and proteins. These may include, but are not limited to: antibiotics such as TET, ciprofloxacin, amoxicillin, or metronidazole, anticoagulants, such as activated protein C, heparin, prostracyclin (PGI 2 ), prostaglandins, leukotrienes, antithrombin III, ADPase, and plasminogen activator; steroids, such as dexamethasone, inhibitors of prostacyclin, prostaglandins, leukotrienes and/or kinins to inhibit inflammation; cardiovascular drugs, such as calcium channel blockers; chemoattractants; local anesthetics such as bupivacaine; and antiproliferative/antitumor drugs such as 5-fluorouracil (5-FU), taxol and/or taxotere. These supplemental compounds may also include polyclonal, monoclonal or chimeric antibodies, or functional derivatives or fragments thereof. They may be antibodies which, for example, inhibit smooth muscle proliferation, such as antibodies to PDGF, and/or TGF-β, or the proliferation of other undesirable cell types within and about the area treated with the TS. These antibodies can also be useful in situations where anti-cancer, anti-platelet or anti-inflammatory activity is needed. In general, any antibody whose efficacy would be improved by site-directed delivery may benefit from being used with this TS delivery system.
Assays for Assessing the Wound Healing Properties of a Growth Factor-Supplemented TS
In order to ascertain whether a particular growth factor-supplemented TS promotes wound healing and to select optimal concentrations of the growth factor(s) to do the same, the composition may be tested by any means known to those of skill in the art (see, e.g., Tsuboi et al., J. Exp. Med. 172:245–251 (1990); Ksander et al., J. Am. Acad. Dermatol. 22:781–791 (1990); and Greenhalgh et al., Am. J. Path. 136:1235 (1990)). Any method including both in vivo and in vitro assays, by which the activity of the selected growth factor(s) in the TS composition can be assessed may be used. For example, the activity of HBGF-1β has been assessed using two independent in vitro assays. In the first, the proliferation of endothelial cells that had been suspended in a shallow fluid layer covering a plastic surface which had been impregnated with growth factor-supplemented FG was measured. In the second, the incorporation of 3 H-thymidine in cultured fibroblasts in the presence of HBGF-1 was measured.
In an in vivo assay, FG that had been supplemented with HBGF-1β has been tested for its ability to promote healing in vivo using mice as a model system. In this method identical punch biopsies were made in the dorsal region of the mice, which were then separated into test, treated control and untreated control groups. The wounds in the mice in the test group were treated with the growth factor-supplemented TS. The wounds in the mice in the treated control group were treated with unsupplemented TS. The wounds in the untreated group were not treated with TS. After a time sufficient for detectable wound healing to proceed, generally a week to ten days, the mice were sacrificed and the wound tissue was microscopically examined to histologically assess the extent of wound repair in each group.
The ability of the growth factor-supplemented TS to induce cell proliferation and to recruit cells may also be assessed by in vitro methods known to those of skill in the art. For example, the in vitro assays described above for measuring the biological activity of growth factors and described in detail in the Examples, may be used to test the activity of the growth factor in the TS composition. In addition, the effects of adding inhibiting and/or potentiating compounds can also be assessed.
Generally, the necessity for adding inhibiting and/or potentiating compounds can be empirically determined. For example, in the experiments described below, the HBGF-1β in HBGF-1-supplemented FG was specifically cleaved in a stochastic manner, suggesting that a component of the FG preparation, most likely thrombin, was responsible. Heparin, which is known to bind to HBGF-1 and protect it from certain proteolytic activities, was added to the HBGF-1-supplemented FG. The addition of relatively low concentrations of heparin protected HBGF-1β from cleavage that would destroy its biological activity in the FG. Therefore, TS compositions that include HBGF-1 may include heparin or some other substance that inhibits the cleavage of HBGF-1 by thrombin or other proteolytic components of the FG.
Similarly, the ability of a selected inhibitor to protect a growth factor from degradation by TS components may be assessed by any method known to those of skill in the art. For example, heparin has been tested for its ability to inhibit cleavage of HBGF-1 by thrombin, which is an essential component of FG. To do so, mixtures of various concentrations of heparin and HBGF-1-supplemented FG have been prepared, and incubated for various times. The biological activity of HBGF-1 in the mixture has been tested and the integrity of the HBGF-1 has been ascertained using western blots of SDS gels. Relatively low concentrations, about a 1:1 molar ratio of heparin:HBGF-1, are sufficient to protect HBGF-1 from degradation in FG.
It can also be empirically determined whether a particular compound can be used to potentiate, mediate or enhance the biological activity of a growth factor(s) in TS.
Topical or Internal Application of the Growth Factor-Supplemented TS to an Internal or External Wound
Prior to clinical use, the growth factor and TS, or the growth factor-supplemented TS is pasteurized or otherwise treated to inactivate any pathogenic contaminants therein, such as viruses. Methods for inactivating contaminants are well-known to those of skill in the art and include, but are not limited to, solvent-detergent treatment and heat treatment (see, e.g., Tabor et al., Thrombosis Res. 22:233–238 (1981) and Piszkiewicz et al., Transfusion 28:198–199 (1988)).
The supplemented TS is applied directly to the wound, other tissue or other desired location. Typically for external wounds it can be applied directly by any means, including spraying on top of the wound. It can also be applied internally, such as during a surgical procedure. When it is applied internally, such as to bones, the clot gradually dissolves over time.
Self-Contained Applications of the Supplemented or Unsupplemented TS for Internal or External Wounds
The TSs may be formulated as a self-contained wound dressing, or fibrin sealant bandage, which contains the necessary thrombin and fibrinogen components of the FG. The self-contained dressing or bandage is easy-to-use, requiring no advanced technical knowledge or skill to operate. It can even be self-administered as an emergency first aid measure to preserve life until medical assistance becomes available.
The self-contained TS wound dressing or fibrin sealant bandage is an advancement over the current technology in that the field-ready preparation can be stored for long periods, and be used to provide rapid TS treatment of a hemorrhaging wound without the time delay associated with solubilization and mixing of the components. These characteristics make it ideal for use in field applications, such as in trauma packs for soldiers, rescue workers, ambulance/paramedic teams, firemen, and in early trauma and first aid treatment by emergency room personnel in hospitals and clinics, particularly in disaster situations. A small version may also have utility in first aid kits for use by the general public or by medical practitioners.
The self-contained TS wound dressing or fibrin sealant bandage comprises a tissue sealing composition comprising a tissue sealant or fibrin complex of the type previously described. For example, the composition may be comprised of purified fibrinogen, thrombin and calcium chloride with sufficient Factor XIII to produce a fibrin clot. In one embodiment the fibrinogen and Factor XIII components are supplied in the form of topical fibrinogen complex (TFC).
When used on human patients, the components are most preferably pathogen-inactivated, purified components derived from human sources. In particular, the components of the present invention, including additives thereto, are treated with a detergent/solvent, and/or otherwise treated, e.g., by pasteurization or ultrafiltration to inactivate any pathogenic contaminants therein, such as viruses. Methods for inactivating contaminants are well-known to those of skill in the art and include, but are not limited to, solvent-detergent treatment and heat treatment. Solvent-detergent treatment is particularly advantageous in that the proteinaceous components are not exposed to irreversible heat-denaturation.
The calcium and/or Factor XIII components may be contained in either the thrombin and/or the fibrinogen component(s), and/or absorbed from the patient's endogenous calcium present in the fluids escaping from the wound. Thrombin may also be supplied endogenously. Either or both of the thrombin or fibrinogen components can be, but does not have to be, supplemented in each of the following embodiments with one or more growth factors, drugs, inhibiting compounds (to inhibit the activities of the sealant that may interfere with any of the biological activities of the growth factor or drug), and potentiating compounds (to potentiate, mediate or enhance any of the biological activities of the growth factor or drug), compounds which inhibit the breakdown of the fibrin clot, or dyes.
The growth factor may include, e.g., fibroblast growth factor-1, fibroblast growth factor-2 and fibroblast growth factor-4; platelet-derived growth factor; insulin-binding growth factor-1; insulin-binding growth factor-2; epidermal growth factor; transforming growth factor-α; transforming growth factor-β; cartilage-inducing factors-A and -B; osteoid-inducing factor; osteogenin and other bone growth factors; collagen growth factor; heparin-binding growth factor-1; heparin-binding growth factor-2; and/or their biologically active derivatives.
The drug may be an analgesic, antiseptic, antibiotic or other drug(s), such as antiproliferative drugs which can inhibit infection, promote wound healing and/or inhibit scar formation. More than one drug may be added to the composition, to be released simultaneously, or the drug may be released in predetermined time-release manner. Such drugs may include, for example, taxol, tetracycline free base, tetracycline hydrochloride, ciprofloxacin hydrochloride or 5-fluorouracil. The addition of taxol to the fibrin sealant complex may be particularly advantageous. Further, the drug may be a vasoconstrictor, e.g., epinephrine; or the drug may be added to stabilize the tissue sealant or fibrin clot, e.g., aprotinin. The supplement(s) is at a concentration in the TS such that it will be effective for its intended purpose, e.g., an antibiotic will inhibit the growth of microbes, an analgesic will relieve pain, etc.
Dyes, markers or tracers may be added, for example, to indicate the extent to which the fibrin clot may have entered the wound, or to measure the subsequent resorption of the fibrin clot, or the dye may be released from the tissue sealant in a predetermined, time-release manner for diagnostic purposes. The dyes, markers or tracers must be physiologically compatible, and may be selected from colored dyes, including water soluble dyes, such as toluidine blue, and radioactive or fluorescent markers or tracers which are known in the art. The dyes, markers or tracers may also be compounds which may be chemically coupled to one or more components of the tissue sealant. In addition, the marker may be selected from among proteinaceous materials which are known in the art, which upon exposure to proteolytic degradation, such as would occur upon exposure to proteases escaping from wounded tissue, change color or develop a color, the intensity of which can be quantified.
Moreover, when the TS is used to replace or repair wounded or damaged bone or ossified tissue, the composition may also be supplemented with effective amounts of demineralized bone matrix and/or bone morphogenic proteins, and/or their biologically compatible derivatives.
The concentration of the fibrinogen and/or thrombin components of the self-contained TS wound dressing or fibrin sealant bandage may have a significant effect on the density and clotting speed of the final fibrin matrix. This principle may be used to satisfy specific uses of the self-contained TS wound dressing or fibrin sealant bandage in specialized situations. For example, the treatment of an arterial wound may require the fibrin clot to set very rapidly and with sufficient integrity to withstand pressurized blood flow. On the other hand, when filling deep crevices in a wound, treatment may require the components to fill the wound completely before the fibrin clot sets.
The Gel Pack Embodiments
In the gel pack embodiment of the self-contained dressing, the thrombin and fibrinogen components are individually contained in independent quick-evaporating gel layers (e.g., methylcellulose/alcohol/water), wherein the two gel layers are separated from each other by an impermeable membrane, and the pair are covered with an outer, protective, second impermeable membrane. The bandage may be coated on the surface that is in contact with the gel in order to insure that the gel pad remains in place during use. (See FIG. 42 ).
In use, the membrane separating the two gel layers is removed, allowing the two components to mix. The outer membrane is then removed and the bandage is applied to the wound site. The action of the thrombin and other components of the fibrinogen preparation cause the conversion of the fibrinogen to fibrin, in the manner previously disclosed for other FS applications. This results in a natural inhibition of blood and fluid loss from the wound, and establishes a natural barrier to infection.
In a similar gel pack embodiment, both the thrombin component, and the plastic film separating the thrombin gel and the fibrinogen gel, may be omitted. In operation, the outer impervious plastic film is removed and the bandage applied, as previously described, directly to the wound site. The thrombin and calcium naturally present at the wound site then induce the conversion of fibrinogen to fibrin and inhibit blood and fluid loss from the wound as above.
This alternative embodiment of the gel pack has the advantage of being simpler, cheaper, and easier to produce. However, there may be circumstances in which a patient's wounds have insufficient thrombin to effectively transform the fibrinogen gel into a fibrin tissue sealant. In those cases, the thrombin component must be exogenously supplied, as in the earlier-described gel pack embodiment of the invention.
The Fibrin Sealant Bandage Embodiments
A fibrin sealant bandage embodiment is formulated for applying a tissue sealing composition to wounded tissue in a patient, wherein the bandage comprises, in order: (1) an occlusive backing; (2) a physiologically-acceptable adhesive layer on the wound-facing surface of the backing; and (3) a layer of dry materials comprising an effective amount, in combination, of (a) dry, virally-inactivated, purified fibrinogen complex, (b) dry, virally-inactivated, purified thrombin, and as necessary (c) effective amounts of calcium and/or Factor XIII to produce a tissue-sealing fibrin clot upon hydration, wherein the layer of dry materials is affixed to the wound-facing surface of the adhesive layer. In one embodiment, the occlusive backing and the physiologically-acceptable adhesive layer are one and the same, if the backing layer is sufficiently adhesive to effectively bind the layer of dry materials.
In another embodiment, a removable, waterproof, protective film is placed over the layer of dry materials and the exposed adhesive surface of the bandage for long-term stable storage. In operation the waterproof, protective film is removed prior to the application of the bandage over the wounded tissue.
The tissue sealant component of the bandage in one embodiment is activated at the time the bandage is applied to the wounded tissue to form a tissue sealing fibrin clot by the patient's endogenous fluids escaping from the hemorrhaging wound. Preferably, the tissue sealant is hydrated and fluid loss from the wound will be significantly diminished within minutes of application of the bandage to the wounded tissue. Although the speed with which the fibrin clot forms and sets may be to some degree dictated by the application, e.g., rapid setting for arterial wounds and hemorrhaging tissue damage, slower setting for treatment of wounds to bony tissue, preferably the fibrin clot will form within twenty minutes after application. More preferably, this effect will be evident within ten minutes after application of the bandage. Most preferably, the fibrin clot will form within two to five minutes after application. In the embodiment comprising the most rapidly forming fibrin clot, the tissue seal will be substantially formed within 1–2 minutes, more preferably within 1 minute, and most preferably within 30 seconds after application.
It may be necessary to use pressure in applying the fibrin sealant bandage until the tissue sealing fibrin clot has formed over the wound site.
In the alternative, in situations where fluid loss from the wound is insufficient to provide adequate hydration of the dry tissue sealant materials, or where time is of the essence, as in a life-threatening situation, the tissue sealant components are hydrated by a suitable, physiologically-acceptable liquid prior to application of the bandage to the wounded tissue.
To construct the bandage, the dry materials may be obtained, for example, by lyophilization or freeze-drying, or suitable, commercially-available materials may be utilized. Anhydrous CaCl 2 may also be added to the dry TS components to accelerate the speed of fibrin formation upon hydration of the fibrin sealant bandage. The binding of the dry materials to the adhesive or backing layer may be enhanced by adding a binder, preferably a water soluble binder, to the dry components.
The backing of the fibrin sealant bandage may be of conventional, non-resorbable materials, e.g., a silicone patch or plastic material; or it may be of biocompatible, resorbable materials. The backing material may act as more than a delivery device. Its preferred composition is determined by the desired application of the fibrin sealant bandage. For example, a non-resorbable backing is appropriate for many external uses, where it provides strength and protection for the fibrin clot. In an alternative embodiment, the non-resorbable backing is reinforced, e.g., with fibers, to provide extra strength and durability for the protective covering over the fibrin clot.
Subsequent removal of the clot with the backing is acceptable in many situations, such as when the fibrin sealant bandage is used as a first aid measure until medical assistance becomes available. In such a situation, the clot will have served its purpose to prevent life threatening loss of fluid, and it will be desirable to remove the clot without causing additional tissue damage to permit proper treatment or surgical repair of the wound.
In the alternative, the non-resorbable backing may be used to provide strength to the tissue sealing fibrin clot during its formation, e.g., when the hemorrhaging fluids are escaping under pressure, as in an arterial wound. Yet, if such a wound is internal, it is advantageous to remove the backing from the fibrin clot without disturbing the tissue seal. Therefore, a fibrin sealant bandage is provided in which the adhesive layer is of a material having a lower shear strength than that of the fibrin clot, permitting removal of the backing without damage to the fibrin clot or the tissue surrounding the wound.
By comparison, certain internal applications mandate the use of a resorbable backing to eliminate the need for subsequent removal of the dressing. A resorbable material is one which is broken down spontaneously or by the body into components which are consumed or eliminated in such a manner as to not significantly interfere with healing and/or tissue regeneration or function, and without causing any other metabolic disturbance. Homeostasis is preserved. Materials suitable for preparing the biodegradable backing include proteinaceous substances, e.g., fibrin, collagen, keratin and gelatin, or carbohydrate derived substances, e.g., chitin, chitosan, carboxymethylcellulose or cellulose, and/or their biologically compatible derivatives.
The adhesive layer, if separate from the occlusive backing layer, is selected on the basis of the intended application of the fibrin sealant bandage, and may comprise conventional adhesive materials. Antiseptic may be added to the adhesive layer.
If the tissue sealing fibrin clot is to be removed from the wound with the occlusive backing, such as prior to surgery, the adhesive must be sufficient to affix the dry material layer to the occlusive backing, and to maintain an adhesive capability after hydration which is greater than the sheer strength of fibrin.
If the tissue sealing fibrin clot is to remain in position over the wound, but the occlusive backing must be removed after application, the adhesive must be sufficiently sticky to affix the dry material layer to the occlusive backing, but yet have an adhesive capability after hydration which is less than the sheer strength of the fibrin clot. In the alternative, the adhesive layer may be of a material which becomes solubilized or less sticky during hydration of the dry materials, permitting removal of the backing from the fibrin clot. In the alterative for such purposes, the dry material layer may be affixed directly to the occlusive bandage.
In another embodiment, the adhesive layer comprises two different adhesives to permit removal after hydration of the occlusive layer without disturbing the tissue sealing fibrin clot. Typically, in such a situation the dry, tissue-sealant component materials are affixed to a specific region of the backing, the “inner region,” e.g., the center, with an unencumbered area of adhesive extending beyond the area of dry material, the “outer region.”
The outer region of adhesive is affixed directly to the skin or tissue surrounding or adjacent to the wound in such a way that the dry material region of the bandage forms a fibrin clot directly over the wound. The adhesive layer on the region of backing which is not covered by the dry material layer of the bandage is sufficient to affix the fibrin sealant bandage to the tissue surrounding the wound until its physical removal. The adhesive on the outer region must be sufficient to hold the bandage in place, even if fluids are hemorrhaging from the wound under pressure, e.g., an arterial wound.
The inner region of adhesive is sufficiently sticky to affix the dry material layer to the occlusive backing, but yet have an adhesive capability after hydration which is less than the sheer strength of the fibrin clot. In the alternative, the inner region of adhesive is of a material which becomes solubilized or less sticky during hydration of the dry materials, permitting removal of the backing from the fibrin clot. In the alterative for such purposes, the dry material layer may be affixed in the inner region directly to the occlusive bandage, with an adhesive layer added only to the outer layer.
Thus, in the two adhesive embodiment, the backing of the fibrin sealant bandage remains in place affixed to the tissue surrounding the wound until the bandage is physically removed. But upon removal, the backing separates from the tissue sealing fibrin clot without disturbing the tissue seal.
The Dual-Encapsulated Embodiments of the Fibrin Sealant Bandage
In yet another embodiment of the fibrin sealant bandage, an independent hydrating layer comprising an effective amount of carbonated water or physiologically-acceptable buffered hydrating agent, such as PBS, or comparable gel, is contained within a rupturable, liquid-impermeable container. The rupturable, liquid-impermeable container encapsulating the hydrating layer is affixed directly to the above-described occlusive bandage layer or to the above-described adhesive layer adjacent to the occlusive bandage. Affixed to the exposed side (the side which is not attached to the backing or adhesive layer) of the rupturable, liquid-impermeable container encapsulating the hydrating layer is a dry layer of finely-ground, powdered fibrin components, as described above. The layer of dry components includes powdered fibrinogen or fibrinogen complex, thrombin, and as necessary sufficient calcium and/or Factor XIII to, upon hydration, form a fibrin clot.
The dual layers (the dry layer and the hydrating layer) are together covered on all surfaces not in contact with the occlusive backing or adhesive material affixing the layers to the occlusive backing, with an outer, protective, second impermeable membrane. Thus, in this dual-layer embodiment, the contents are entirely encapsulated within an impermeable container, wherein one side is the occlusive backing material and the other side and all edges are formed by the outer, protective, second impermeable membrane.
In operation, the inner liquid-impermeable container encapsulating the hydrating layer is physically ruptured to release the hydrating material contained therein into the dry fibrin component layer, resulting in a fully-hydrated tissue sealing fibrin clot to inhibit blood and fluid loss from the wound, and to provide a natural barrier to infection. The outer, second impermeable membrane retains the released hydrating material in contact with the dry components until a malleable fibrin complex forms, at which time the outer membrane is physically removed and the bandage placed over the wound to form a tissue sealant.
In the alternative, the outer membrane may be physically removed, and the dual layers forcefully applied to the wound area in a manner which ruptures the inner liquid-impermeable container and releases the hydrating agent into the dry fibrin components so that the tissue sealing fibrin clot is formed directly on the wounded tissue.
As in other embodiments of the fibrin sealant bandage, the selected adhesives and backing materials may be determined by the intended application of the bandage. The backing may be removable or resorbable, and the adhesive may have the intended purpose upon removal of the bandage of removing the tissue sealant from the wound, or of leaving the tissue sealing fibrin clot undisturbed. The adhesive may be a separately bound layer, or the backing may itself act as an adhesive to affix the dry fibrin components.
The thrombin, calcium and Factor XIII components which are necessary to form the fibrin complex may be affixed as dry material(s) in the dry material layer, or they may be included in liquid or gel form in the hydrating layer. Moreover, they may be divided between the two layers, so long as all of the necessary fibrin-forming components are present, and the dry layer remains non-hydrated until the bandage is used. In addition, additives, such as the previously disclosed growth factors, antibiotics, antiseptics, antiproliferative drugs, etc. may also be included in this embodiment of the fibrin sealant bandage.
If the hydrating layer contains a liquid supersaturated with gas, the dry material layer will be hydrated as an expandable, foaming, fibrin tissue sealant. In the alternative, the dry material layer may be supplemented with materials which produce gas, and hence foaming, upon contact with the hydrating agent.
If the hydrating layer is in the form of a gel, such as a quick-evaporating gel layers (e.g., methylcellulose/alcohol/water), the rupture of the surrounding impermeable barrier permits the dry material fibrin components to directly contact the hydrating layer as disclosed above to produce the tissue sealing fibrin clot. The gel layer, in the manner described for a liquid hydrating layer, may comprise any one, or all, of the thrombin, calcium or Factor XIII elements of the fibrin complex, and/or any one of the above-disclosed additives.
In an alternate dual layer embodiment, the tissue sealant is delivered as a wound sealing dressing, which need not be affixed to a backing. The components are organized essentially as a capsule within a capsule, wherein the term capsule is used to define a broad concept, rather than a material. The above-described encapsulated hydrating layer is itself contained within a second encapsulating unit, which contains both the dry fibrin component materials and the encapsulated hydrating layer.
In operation, the inner, liquid-impermeable container encapsulating the hydrating layer is physically ruptured to release the hydrating material contained therein into the dry fibrin component layer, both of which remain completely contained within the outer, second encapsulating unit. The integrity of the outer, second encapsulating unit is not broken when the inner container encapsulating the hydrating layer is physically ruptured.
The mixing of the hydrating layer with the dry fibrin components within the outer encapsulating unit results in a fully-hydrated tissue sealing fibrin clot, which is then released or expelled onto wounded tissue to form a tissue seal. To release the fibrin mass, the outer encapsulating unit is physically cut or torn, either randomly or at a specific location on the surface, e.g., to form a pour spout to direct the flow of the malleable fibrin mass onto the wound site.
If the hydrating layer is a agent supersaturated with gas, the mixing of the hydrating agent with the dry fibrin components results in an expandable foaming mixture, which is then applied to the wounded tissue. The foaming may, in the alternative, be achieved by hydration of the dry component layer.
The Self-Foaming Fibrin Sealant Embodiments
A self-foaming fibrin sealant dressing embodiment for treating wounded tissue in a patient is formulated as an expandable foam comprising a fibrin-forming effective amount, in combination, of (1) virally-inactivated, purified fibrinogen, (2) virally-inactivated, purified thrombin, and as necessary (3) calcium and/or Factor XIII; wherein said composition does not significantly inhibit full-thickness skin wound healing. The previously described TS components are stored in a canister or tank with a pressurized propellant, so that the components are delivered to the wound site as an expandable foam, which will within minutes form a fibrin seal.
Acceptable formulations of the expandable foam embodiment provide the hydrated components of a fibrin clot, which in operation expand up to twenty-fold. The extent of expansion of the tissue sealing fibrin clot, however, is determined by its intended application.
For example, use of the expandable foam fibrin sealant dressing within the abdomen provides a fibrin tissue sealant to significantly diminish or prevent blood or fluid loss from injured internal tissues organs or blood vessels, while also providing a barrier to infection. However, at the same time the expansion of the foam must be controlled to prevent harmful pressure on undamaged tissue, organs or blood vessels. Such a situation may warrant the use of an expandable foam dressing in which the expansion is limited to only 1- or 2-fold, and not more than 5–10 fold.
By comparison, use of the expandable foam fibrin sealant dressing to fill gaps within bone, may warrant the use of material which expands at a much greater rate to produce a tight and firm seal over the wounded area. Arterial wounds may also respond well to a highly pressurized foam tissue sealant dressing. The extent of the expansion of such material may be in the range of above 20-fold, although preferably 10–20 fold, or more preferably 5–10 fold. An expansion of less than 5-fold, including 1- to 2-fold may also be applicable to repair of blood vessels or injured bone, for example in small areas, such as the inner ear.
Like the expansion rate, the set-up time for the formation of the fibrin seal using the expandable foam fibrin dressing is also related to its intended application. In certain situations loss of life may be imminent, such as in a patient who has suffered arterial wounds or damaged heart tissue. In such a situation the fibrin dressing must expand very rapidly and form the fibrin tissue seal as quickly as possible, necessarily before exsanguination. Preferably the seal will set-up and significantly diminish the patient's fluid loss within 2 minutes or less, more preferably in 1–2 minutes, and most preferably in less than 1 minute.
On the other hand, not all wounds are immediately life threatening. For example, the strength of the tissue sealant repair of bony tissue is more important than a rapid set-up time. In such situations, the composition of the tissue sealing fibrin clot may be modified to permit greater cross-linking or thickening of the fibrin fibrils, or to permit delivery of a more dilute composition which will continue to expand for a longer period of time. Such formulations may either permit or require a slightly longer time to set-up the tissue sealing fibrin clot. Although a set-up time of under 1 minute is appropriate for such applications, set-up times of 1–2 minutes, or up to 5 minutes would be acceptable. In circumstances recognizable to one of ordinary skill in the art, a long set-up time of 5–10 minutes, or even up to twenty minutes, may be acceptable in non-life threatening situations.
The delivery devices, e.g., canister, tank, etc., may be developed especially for the present application, or they may be commercially available. The canister may comprise either a single or multiple reservoirs. Separate reservoirs, although more expensive, will advantageously permit the hydrated components to remain separated and stable until they are mixed upon application.
The propellant must be physiologically acceptable, suitable for pharmacological applications, and may include conventionally recognized propellants, for example, CO 2 , N 2 , air or inert gas, such as freon, under pressure. In the alternative, the dry fibrin components may be supplemented with material(s) which produce gas, and hence foaming, upon contact with the hydrating agent.
Since delivery pressure of the expandable foam fibrin dressing from the delivery device, when combined with the composition of the fibrin clot itself and its set-up time, determines the extent of expansion of the dressing, the delivery pressure is determined by the nature of the wound being treated. As described above, certain wounds require immediate formation of the tissue sealing fibrin clot to prevent loss of life, while others wounds require slow delivery or time to form extensive cross-links to strengthen the tissue sealing composition. Therefore, delivery pressure may ideally be situation specific.
Pressure of 1 atmosphere, or less (14.7 lbs/inch 2 ) will provide a low level of expansion and a slower rate of delivery. However, certain life threatening situations may warrant a delivery pressure of 1–5 atmospheres, or more. In most cases, the delivery pressure chosen corresponds to that of commercially available canister devices. As an addition factor, the delivery pressure may be important to keep the tissue sealant material from clogging delivery lines or devices.
Combined Embodiments of the Self-Contained Wound Dressing and Fibrin Sealant Bandage
Finally, certain traumatic injuries will be best treated by combining several embodiments of the self-contained fibrin sealant dressing. For example, in serious car accidents or injuries caused by antipersonnel-mines or explosives, the wounds may be not only life-threatening but extensive, involving large, jagged openings in tissue or bone with significant internal damage, often with accompanying serious burns. Such wounds may present numerous severed arteries and blood vessels in addition to extensive areas of wounded tissue. In such wounds, it may be advantageous to first liberally apply a rapidly setting expandable fibrin foam dressing to quickly control hemorrhaging, and then to wrap the entire area in an embodiment of the fibrin sealant bandage to support and protect the wounded area and seal slow fluid loss from, for example, burned tissue, until the victim can be transported to a medical facility, or until professional medical assistance can administered. In most instances, additional formulations of the fibrin sealant dressing will then be applied by the trained personnel for the long-term repair, treatment and protection of the injured tissue.
The following examples are included for illustrative purposes only and are not intended to limit the scope of the invention.
EXAMPLE 1
Preparation of HBGF-1 for Supplementation of FG
An 800 ml culture of recombinant E. coli containing a plasmid that included DNA encoding HBGF-β was prepared. After induction and culturing for 24 hours at 37° C., the cells were centrifuged and the supernatant was discarded. The cell pellet was resuspended in 25 mls of 20 mM phosphate buffer, containing 0.15 M NaCl, pH 7.3. The suspended cells were disrupted with a cell disrupter and the cell debris was separated from the resulting solution by centrifugation at 5000 g for 20 min.
The pellet was discarded and the supernatant containing the solubilized HBGF-1β, and other bacterial proteins was loaded onto a 2.6 cm diameter by 10 cm high column of Heparin-Sepharose™ (Pharmacia Fine Chemicals, Upsala, Sweden). The column was washed with 5 column volumes of 0.15 M NaCl in 20 mM phosphate buffer, pH 7.3, and then was eluted with a 0.15 M NaCl in 20 mM phosphate buffer to 2.0 M NaCl gradient.
The eluate was monitored by UV absorption at 280 nm. Three peaks of UV absorbing material eluted and were analyzed by SDS polyacrylamide gel electrophoresis. Peak number three electrophoresed as a single band at about 17,400 daltons and contained substantially pure HBGF-1β.
In order to further insure that the HBGF-1β was free of contaminating bacterial proteins, peak number three, which contained the growth factor activity, was dialyzed overnight against 20 mM histidine, 0.15 M NaCl, pH 7.5. Two mg of protein was loaded onto a 1 ml CM-Sepharose™ (Pharmacia, Upsala, Sweden) ion exchange column. The column was washed with 10 bed volumes (0.5 ml/min) of 20 mM histidine, 0.15 M NaCl, pH 7.5 and eluted with a gradient of 0.15 M NaCl to 1.0 M NaCl in 20 mM histidine, pH 7.5. The eluate was monitored by UV absorption at 280 nm and HBGF-1β was identified by SDS polyacrylamide gel electrophoresis.
This purified HBGF-1 was used to supplement FG in subsequent examples.
EXAMPLE 2
Stability of HBGF-1
It was necessary to add an ingredient to the FG that would inhibit or prevent the digestion of HBGF-1β by thrombin (Lobb, Biochem. 27:2572–2578 (1988)), which is a component of FG. Heparin, which adsorbs to HBGF-1, was selected and tested to determine whether it could protect HBGF-1 from digestion by thrombin and any other proteolytic components of the FG. The stability of HBGF-1 in the presence of increasing concentrations of heparin was assessed.
Solutions containing HBGF-1β (10 μg/ml), thrombin (250 U/ml), and increasing concentrations of heparin (0, 0.5, 5, 10, 20, and 50 U/ml) were incubated at 37° C. Aliquots were periodically removed from the incubating solutions and were frozen and stored at −70° C. for further testing.
After the incubation was complete, the samples were thawed and separated on 15% SDS polyacrylamide gels under reducing conditions according to the method of Laemmli ( Nature 227:680 (1970)). The gel was then electroblotted onto nitrocellulose and the band corresponding to HBGF-1 was identified using an affinity-purified polyclonal rabbit antiserum to HBGF-1. The Western blots are shown in FIG. 1 on which the HBGF-1β band at 17,400 mw can be seen. The results indicated that in the presence of concentrations of heparin as low as 5 U/ml, HBGF-1β was protected from digestion by thrombin. In addition, as described in Example 3, its biological activity was not altered.
EXAMPLE 3
The Biological Activity of HBGF-1β after Incubation in the Presence of Heparin and Thrombin
The biological activity of HBGF-1 in the incubation mixture that contained 5 U/ml of heparin, and was described in Example 2, was measured using an 3 H-thymidine incorporation assay with NIH 3T3 cells.
NIH 3T3 cells were introduced into 96 well plates and were incubated at 37° C. under starvation conditions in Dulbecco's Modified Medium (DMEM; GIBCO, Grand Island, N.Y.) with 0.5% fetal bovine serum (BCS; GIBCO, Grand Island, N.Y.) until the cells reached 30 to 50% confluence. Two days later, varying dilutions of HBGF-1 from the samples prepared in Example 2 were added to each well without changing the medium. Diluent (incubation buffer) was added in place of growth factor for the negative controls and DMEM with 10% BCS, which contains growth factors needed for growth, was added in place of the HBGF-1 sample for the positive controls.
After incubation at 37° C. for 18 hours, 0.25 μCi of 3 H-thymidine, specific activity 6.7 μCi/mol, was added to each well and the incubation was continued at 37° C. for an additional 4 hours. The plates were rinsed with phosphate-buffered saline (PBS) and fixed with 0.5 ml cold 10% trichloracetic acid (TCA) for 15 min at 4° C. The TCA was removed, the plates were rinsed with PBS and the acid-precipitable material was solubilized with 0.5 ml/well of 0.1 N sodium hydroxide for 1 hour at room temperature. The samples were transferred to scintillation vials and 10 ml of scintillation fluid (New England Nuclear, Aquasure™) was added per vial.
The results, which are shown in FIG. 2 , demonstrated that HBGF-1, which had been incubated in the presence of thrombin and heparin, retained its biological activity. The observed concentration dependence of thymidine incorporation was independent of incubation time and was typical of that expected for the dependence of the proliferation of cells as a function of growth factor concentration. Growth factors typically exhibit an optimal concentration at which cell proliferation is maximal.
The biological activity of HBGF-1 in the presence of thrombin and heparin was also measured by observing endothelial cell proliferation. The surfaces of petri dishes were impregnated with the HBGF-1 supplemented FG. A shallow layer of endothelial cells was added and the number of cells was measured. Over time the number of cells increased. In addition, the cells appeared to be organizing into vessels.
Therefore, HBGF-1 retains its biological activities in FG that includes heparin, which protects HBGF-1 from the degradative activity of thrombin and may also potentiate the biological activity of the HBGF-1 in the growth factor-supplemented FG.
EXAMPLE 4
HBGF-1 Diffusion from a FG Clot
A FG clot was formed in a 5 ml plastic test tube by mixing 0.3 ml of the fibrinogen complex containing 10 U/ml heparin and thrombin and 40 mM CaCl 2 . Four test tubes were set up as follows:
(A) 0.5 U/ml thrombin and 10 μg/ml HBGF-1;
(B) 0.5 U/ml thrombin and 50 μg/ml HBGF-1;
(C) 5 U/ml thrombin and 10 μg/ml HBGF-1; and
(D) 5 U/ml thrombin and 50 μg/ml HBGF-1.
Each clot was covered with 0.2 M histidine buffer, pH 7.3. Thirty μl samples of the overlying buffer were removed from each tube every two hours and were run on a western blot.
The results of the experiment demonstrated that HBGF-1 diffusion out of the clot is a function of time and its concentration in the clot, and that the concentration of thrombin in the clot does not affect the rate at which HBGF-1 is released from the clot.
EXAMPLE 5
The Behavior of Human Umbilical Vein Endothelial Cells in Growth Factor-Supplemented FG: The Effect of Wild Type and Mutant FGF-1
To study the in vitro effects of acidic fibroblast growth factor (FGF-1)-supplemented FG on human endothelial cells, suspensions of these cells were added to 10 cm diameter petri dishes that contained evenly spread layers of 2.5 ml of FG containing approximately 9 mg of fibrinogen per ml and 0.25 NIH units of thrombin per ml. The FG was supplemented in the following ways:
(A) No added growth factor;
(B) Supplemented with 100 ng/ml of active, wild-type FGF-1;
(C) Supplemented with 100 ng/ml of inactive, mutant FGF-1; or
(D) Supplemented with 10 ng/ml of active, wild-type FGF-1.
The cells seeded onto the FG layer were maintained for 7 days in DMEM containing 10% fetal bovine serum (FBS).
The cells became elongated and proliferated efficiently when in contact with FG supplemented with biologically active FGF-1 ( FIGS. 3 and 4 ). In contact with unsupplemented FG ( FIG. 5 ) or with FG supplemented with biologically inactive mutant FGF-1 ( FIG. 6 ), the cells become elongated but proliferated relatively slowly.
EXAMPLE 6
The Behavior of Human Umbilical Vein Endothelial Cells in FGF-1-Supplemented FG
To study their growth, human umbilical endothelial cells, 10 5 or more cells per ml, were embedded in FG, the protein concentration of which was 4 mg/ml. The concentration of thrombin in the FG was adjusted to 0.6 NIH U/ml. The culture medium used in all of the experiments was M199 (Sigma Chemical Co., St. Louis, Mo.) supplemented with 10% fetal bovine serum, 10 μg/ml streptomycin, 100 U/ml penicillin, 1 ng/ml FGF-1 and 10 U/ml heparin.
Within 24 hours in FG the cells became elongated, multipodial and formed a cellular network when they came in contact with each other ( FIG. 7 ). This growth continued for at least 5 days. FIG. 8 shows this situation at 48 hours.
As a control, an identical cell suspension was cultured on a surface coated with fibronectin at 10 μg/cm 2 . Control cells acquired a cobblestone shape and maintained this morphology for at least 5 days. FIGS. 9 and 10 show this situation at 24 and 48 hours, respectively.
EXAMPLE 7
The Behavior of PMEXNEO-3T3-2.2 Cells in FG
PMEXNEO-3T3-2.2 cells are fibroblast cells that contain a modified genome with the potential to express genetically engineered proteins (Forough et al., J. Biol. Chem. 268:2960–2968 (1993)). To determine the behavior of these cells in FG, 10 5 cells per well were cultured under three conditions: (1) embedded in FG; (2) on the surface of FG; and (3) in the absence of FG (controls). The experiments were carried out in duplicate in 24-well plates in DMEM media (Sigma Chemical Co., St. Louis, Mo.) supplemented with 10% FBS. The FG protein concentration was 4 mg/ml. In identical experiments the medium was supplemented with 1.5% FBS was used as negative controls.
In the presence of media supplemented with 10% FBS, the cells in all 3 groups grew and became confluent. In the negative control experiments in which the media was supplemented with 1.5% FBS, the cells grew and survived for at least five days in the presence of FG, but not without it. However, their growth was faster in FG supplemented with 10% FBS than in that supplemented with 1.5% FBS. In the absence of FG, in the media supplemented with 1.5% FBS, the cells died within 48 hours. The criteria for survival was the ability of the tested cells to proliferate upon transfer to fresh media supplemented with 10% FBS.
EXAMPLE 8
The Endothelialization of Expanded PTFE Vascular Grafts by HBGF-1 Pretreatment
Two studies demonstrated that pretreatment of blood-contacting biomaterials with endothelial cell (EC) mitogens enhanced endothelialization. The first study examined the in vivo washout characteristics of HBGF-1-supplemented FG suspension applied to expanded PTFE grafts implanted into rabbit aortas. In the second study similar grafts were implanted into the aortaileac position in dogs. HBGF-1, an angiogenic factor, was used in studies. Other growth factors such as a FGF, FGF-4 and/or OP-1 can also be used as a supplement(s) for the vascular grafts.
A. Washout Study
In general, the modified FG was sterilely prepared by adding approximately 1 ng/cm 2 area of the inner and outer graft surfaces of human recombinant 125 I-HBGF-1, 20 μg/cm 2 porcine intestinal mucosal heparin, and 2.86 mg/cm 2 fibrinogen to 2.86×10 −2 U/cm 2 reconstituted, commercially available, human thrombin (1000 U/ml) to induce polymerization.
The 125 I-HBGF-1 was specifically prepared as follows. Fibrinogen was reconstituted by adding 500 mg of fibrinogen into 25 ml of PBS to produce a fibrinogen concentration of 20 mg/ml of PBS. Three ml of this solution which contained 60 mg fibrinogen were placed into 12 Eppendorf plastic tubes and maintained at −70° C. Each of these aliquots was used individually.
The thrombin was reconstituted by diluting a commercially available preparation thereof (Armour Pharmaceutical Co., Kankakee, Ill.) at a concentration of 1000 U/ml by a factor of 1:10 in sterile solution to produce a concentration of 100 U/ml. This thrombin solution was again diluted 1:10 to produce a solution of 10 U/ml.
The bovine heparin (Upjohn, Kalamazoo, Mich.) was reconstituted by diluting the preparation at a concentration of 1000 U/ml by a factor of 1:1000 using normal saline.
One and 48/100 (1.48) ml of the reconstituted fibrinogen, 63/L of the reconstituted heparin, plus 15.66 μL of 125 I-HBGF-1 were mixed in a glass scintillation tube. This mixture was then aspirated into a 3 ml plastic syringe. Five ml of the reconstituted thrombin was placed into a glass scintillation tube.
One end of the expanded PTFE graft was placed over a plastic 3-way stopcock nozzle and was secured there with a 2-0 silk tie. The PTFE was then encircled with a 3×3 cm square of Parafilm™ which was then crimped there with a straight hemostat to establish a watertight seal. A second 2-0 silk tie was positioned over the parafilm adjacent to the stopcock to form another seal. A straight hemostat was then used to clamp the distal 2 mm of the PTFE/parafilm to seal this end.
Equal volumes of fibrinogen and thrombin solution prepared as described above were mixed and allowed to react for approximately 30 seconds which is when polymerization occurs. The thrombin-polymerized fibrin is then opaque. (This time factor is approximate and varies from one thrombin lot to another. The appropriate length of time to polymerization can be determined by viewing the opacity of the mixture). The fibrin/thrombin mixture was aspirated into a one cc syringe. (NOTE: The volume of this graft was 0.42 ml. For a graft with a larger volume one needs to use a larger syringe.) The syringe was attached to the stopcock and the mixture was injected by hand over a period of 5 seconds until the liquid was seen to “sweat” through the PTFE interstices and filled the space between the PTFE and the Parafilm™. The 3-way stopcock was closed to the PTFE graft for 3 minutes and a scalpel blade was used to cut the ligature at the end of the PTFE over the stopcock. The PTFE graft/parafilm was removed from the stopcock and a hemostat was used to remove the PTFE from the parafilm envelope. To clear residual growth factor-supplemented FG from the graft lumen, a number 3 embolectomy catheter was passed through the graft five times until the graft lumen was completely clear. The growth factor-supplemented FG-treated PTFE graft was allowed to dry overnight for about 12 hours under a laminar flow hood. The treated graft was then ready for implantation.
Alternatively, this HBGF-supplemented FG was pressure perfused into a 34 mm (24 mm+5 mm at each end)×4 mm (internal diameter) thin-walled, expanded PTFE graft thereby coating the graft's luminal surface and extending through the nodes to the graft's outer surfaces. The lumen of the graft was cleared as stated above. These grafts were then interposed into the infrarenal abdominal aortas of 24, 3–5 Kg New Zealand white rabbits. In the first study, the animals were sacrificed and specimens were explanted at 0 time (to correct for losses due to surgical manipulation) and after 5, 30, and 60 min, and 1, 7, 14, and 30 days. Residual radioactivity was determined by gamma counting. Remaining 125 I-HBGF-1, corrected for spontaneous decay, is expressed as a percentage of the zero time value.
The washout of 125 I-HBGF-1 followed classic kinetics with a rapid initial loss with the reestablishment of circulation (%/min=−24.1 between 5 and 60 minutes) followed by a slow loss after 1 hr (%/min=−0.03) with 13.4%±6.9% remaining after 1 week and 3.8%±1.1% remaining after 30 days.
B. In Vivo Endothelialization Study
The second study evaluated the effects of the applied HBGF-1-supplemented FG suspension on: the rate of endothelialization of widely expanded 60 μm internodal distance expanded PTFE grafts implanted into canine aorta-iliac positions; the proliferative activity of these endothelial cells as a function of time; and the relative contributions of the HBGF-1 and the FG in stimulating the observed endothelial cell proliferation. Three groups of 50×4 mm non-reinforced expanded PTFE grafts were implanted in the aortailiac position of 12 dogs. Group 1 (n=6) contained 20 μg/cm 2 heparin, 2.86 mg/cm 2 fibrinogen and 2.86×10 −2 U/cm 2 of human thrombin plus 1 ng/cm 2 of HBGF-1. Group 2 (n=3) contained the same FG without HBGF-1. Group 3 (n=3) consisted of identical but untreated control grafts. Tritiated thymidine ( 3 H-TdR; 0.5 μCi/kg) was injected in 10 hours before explantation. Grafts were explanted at 7 and 28 days for light and electron microscopy, Factor VIII immunohistochemistry, and en face autoradiography for endothelial cell proliferation in random high power fields. Each graft was viewed by three observers who did not know from which treatment group the graft came. Differences in endothelial cell proliferation were statistically analyzed by two-way ANOVA and independent t-tests.
At 7 days 33% of both the FG and HBGF-1-supplemented FG grafts demonstrated non-contiguous foci of endothelial cells ( FIG. 11 ). The surface of the control grafts remained a fibrin coagulum. At 28 days, every HBGF-1-supplemented FG showed extensive capillary ingrowth and confluent endothelialized blood contacting surfaces, which were not seen in any specimen of the other two groups ( FIGS. 11 and 12 ). FIG. 12 demonstrates that untreated grafts at 28 days had few visible endothelial cells on their surface (Panel G). Grafts treated with FG alone had about 33% of their surface covered with endothelial cells indicating that FG treatment alone encouraged some reendothelialization (Panel H). However, grafts treated with FG supplemented with HBGF-1 (Panel I) appeared to be completely (>95%) covered with endothelial cells which display the characteristic cobblestone morphology of endothelial cells. Thus, the combination of growth factors delivered by FG was able to encourage essentially the complete covering of the vascular graft with a non-thrombogenic endothelial cell lining. En face autoradiography revealed a statistically significant increase (p<0.05) in 3 H-TdR incorporation into the DNA of endothelial cells in the HBGF-1-supplemented FG grafts at 28 days vs. all other groups both as a function of time and of graft treatment.
These data demonstrate that pressure perfusion of an HBGF-1-supplemented FG suspension into 60μ internodal distance expanded PTFE grafts promotes endothelialization via capillary ingrowth and increased endothelial cell proliferation.
These studies demonstrate enhanced spontaneous re-endothelialization of small diameter vascular grafts, and also a method for stimulating a more rapid confluence of transplanted endothelial cells.
EXAMPLE 9
Delivery of Tributyrin from Fibrin Sealant
The induction of endothelialization of artificial vascular grafts by FGF-1 delivered in fibrin sealant represents an important therapeutic application of the use of supplemented fibrin sealant as a delivery vehicle. Hyperproliferation of smooth muscle cells in arterial walls is a significant component of arteriosclerosis, and in restenosis following angioplasty (Cercek et al., Amer. J. Cardiol. 68:24C (1991)). Therefore, delivery of an anti-proliferative or differentiating agent suitable for intravascular treatment from a supplemented fibrin sealant delivery system was considered to prevent or treat this condition.
In choosing an agent to prevent smooth muscle cell hyperproliferation, a drug with extremely low toxicity was selected as it was important not to induce cell damage that might exacerbate the underlying condition. Butyric acid has been shown to prevent the hyperproliferation of retinoblastoma cells (Kyritsis et al., Anticancer Res. 6:465 (1986)), Swiss 3T3 cells (Toscani et al., J. Biol. Chem. 265:5722 (1990)) and other cell types (Prasad et al., Life Sci. 27:1351 (1980)) by inducing a differentiation program.
An induced prevention of hyperproliferation also has been achieved in smooth muscle cells by a related compound, tributyrin. This effect on smooth muscle cells requires a concentration of tributyrin that is close to saturation, making systemic therapy difficult. Therefore, the following experiment was conducted to demonstrate the efficacy of delivering tributyrin directly to the lesion from a supplemented fibrin sealant composition.
Tributyrin was mixed with thrombin, which was then mixed with fibrinogen to form a fibrin sealant matrix. The supplemented fibrin sealant was placed into 24-well culture plates. Culture medium (2 ml) was then placed in wells containing the tributyrin supplemented fibrin sealant, and these were incubated at 37° C. The medium from a new set of three wells was harvested daily, and the supernatant used to culture proliferating smooth muscle cells (10,000 rat or rabbit smooth muscle cells per well, which had been allowed to attach overnight). After incubation for two days (48 hours), the number of cells in each smooth muscle cell culture was measured using the MTS assay (a bioreduction of the tetrazolium compound MTS (Promega, Madison, Wis.) into a soluble formazan chromatophore detected by spectrophotometry at 490 nm.)
As shown in FIG. 13 , the medium harvested from wells containing fibrin sealant alone supported the growth of the smooth muscle cells, while the medium from wells with fibrin sealant containing tributyrin significantly inhibited smooth muscle cell proliferation. As the number of days of tributyrin diffusion into the medium increased, the degree of inhibition increased. These results indicated that a cell regulatory drug, tributyrin, can be delivered from fibrin sealant for extended periods and that it retains the sustained ability to inhibit the proliferation of a specific cell type.
EXAMPLE 10
Formulation and Delivery of TGF-β2 from Fibrin Sealant
Fibrinogen and thrombin were prepared per instruction of the American Red Cross, Rockville, Md. Upon reconstitution, the protein concentration of the Topical Fibrinogen Complex, (TFC) was 120 mg/ml (the standard formulation for hemostasis). The human thrombin was reconstituted with 40 mM CaCl2 to yield a solution at 300 units/ml.
To evaluate the compatibility of transforming growth factor β2 (TGF-β2) in Topical Fibrinogen Complex, TGF-β2 (purified recombinant human protein provided by Genzyme Corp., Framingham, Mass.) was spiked into TFC at 10 and 1/g/ml. Samples were incubated for two weeks at 2–8° C. TGF-β2 was extracted for analysis by passing the gel-like material through a narrow bore stopcock connected to two syringes. The ELISA data indicated full recovery of TGF-β2 from the TFC. Analysis in the in vitro bio-assay indicated that the extract was bioactive.
TGF-β2 was then spiked into the TFC solution at a concentration of 1 μg/ml or 100 ng/ml. 50 μl aliquots were placed into sterile test tubes and 50 μl of the thrombin solution was added to form the fibrin clot. Clot formation occurred within a few seconds. These samples were allowed to sit overnight at 2–8° C. Test sample tubes were then overlaid with 400 μl of PBS/0.1% human serum albumin pH 7.0, with or without 10 μg/ml plasmin. The test samples were incubated for two days at 37° C. to evaluate the release and recovery of the TGF-β2. Complete resolution of the clot was observed in the plasmin treated samples. The clot remained intact in the non-plasmin treated samples. The diffusion supernatant was analyzed by ELISA. The data are summarized in Table 1.
TABLE 1 TGF-β2 Concentration % Recovery in Diffusion Supernatant (by ELISA) in Fibrin Clot With Plasmin Without Plasmin 500 ng/ml 100% 2.5% 50 ng/ml 100% (not detectable)
Theoretical concentrations of components in the final clot based on dilution: TFC protein=60 mg/ml; thrombin activity=150 units/ml; TGF-β2=500 ng/ml or 50 ng/ml.
The data indicate not only that TGF-β2 is stable in TFC, but that the delivery of TGF-β2 from fibrin sealant by diffusion can be sustained in low amounts. Moreover, the release of TGF-β2 from fibrin sealant requires dissolution of the fibrin clot by plasmin indicating that in vivo delivery of TGF-β2 from the supplemented tissue sealant composition would be mediated by resolution of the fibrin clot. Thus, the mechanism of delivery from the TGF-β2 supplemented tissue sealant composition is readily distinguished from simple diffusion kinetics.
EXAMPLE 11
The Preparation of a Platelet-Derived Extract for Use with FG
Plasma reduced platelets were prepared and pelleted. The supernatant plasma was removed. The pelleted platelets were washed, suspended in buffer containing 50 mM histidine and 0.15 M sodium chloride at pH 6.5, and treated with bovine thrombin. After treatment, the supernatant was collected by centrifugation and aliquots were frozen at −80° C. The extract was thawed and mixed with FG or other TSs.
The platelet extract obtained in this manner was biologically active since it increased the incorporation of radioactive labeled thymidine into the DNA of proliferating NIH3T3 fibroblasts compared to the controls.
To evaluate the effect of platelet extract on wound healing, experiments identical to those carried out below in Example 12 with HBGF-1β were carried out with platelet extract in diabetic mice. From the results of these experiments is clear that, given the low concentration of growth factors in the platelet extract, a dose larger than 100 μg of platelet extract protein per wound needs to be used to promote wound healing.
EXAMPLE 12
The Effect of FG on Skin Wound Healing In Vivo
A. Unsupplemented FG
Animals
Female C57BL/K S J-db/db mice were obtained from Jackson Laboratories (Bar Harbor, Me.) and were 8 to 12 weeks old at the start of the experiment. They were housed in separate cages after surgery in an animal care facility.
These mice are used as a model of impaired wound healing in diabetic humans because the metabolic abnormalities seen in these mice are similar to those found in human diabetics. In addition, the healing impairment characterized by markedly delayed cellular infiltration, granulation tissue formation, and time required for wound closure suggest that healing in this mouse model may be relevant to the healing impairment seen in human diabetes.
Fibrin Sealant
The concentrated topical fibrinogen complex (TFC) used in this study was produced from fresh frozen pooled human plasma. The TFC product (American Red Cross—Baxter Hyland Division, Los Angeles, Calif.) was supplied in lyophilized form. After reconstitution with 3.3 ml of sterile water, the protein characteristics of the TFC solution used in this study were: total protein, 120 mg/ml; fibrinogen, 90 mg/ml; fibronectin, 13.5 mg/ml; Factor XIII, 17 U/ml; and plasminogen, 2.2 μg/ml.
Topical bovine thrombin (5000-unit vial, Armour Pharmaceutical Co., Kankakee, Ill.) was reconstituted with 5 ml sterile water and was serially diluted in 80 mM calcium chloride solution (American Reagent Laboratories, Shirley, N.Y.) to a concentration of 15 U/ml.
Equal volumes of TFC and reconstituted thrombin were mixed to produce FG. In order to fill a round 6-mm-diameter full thickness wound, 0.015 ml of TFC was mixed with 0.015 ml of thrombin. The FG that was produced had a protein concentration of approximately 60 mg/ml.
A diluted FG with a protein concentration of approximately 1 mg/ml was also used.
Surgery
The mice were anesthetized with a mixture consisting of 7 ml ketamine hydrochloride (100 mg/ml; Ketaset, Aveco Co., Inc., Fort Dodge, Iowa), 3 ml xylazine (20 mg/ml; Rompun, Mobey Corp., Shawnee, Kans.), and 20 ml physiological saline, at a dose of 0.1 ml per 100 g body wt, administered intramuscularly. The dorsal hair was clipped, and the skin was washed with povidone-iodine solution and wiped with 70% alcohol solution. Two full-thickness, round surgical wounds (6 mm diameter) were made on the lower back of the mouse, one on each side, equidistant from the midline. The medial edges of the two wounds were separated by a margin of at least 1.5 cm of unwounded skin.
Immediately after the wounding had been performed, FG and/or a dressing was placed over the designated wound. The dressing was a transparent semipermeable adhesive polyurethane dressing (Opsite™, Smith and Nephew, Massillon, Ohio). Tincture of Benzoin compound (Paddock Laboratories, Minneapolis, Minn.) was applied at the periphery of the wound area prior to application of the dressing. There was a margin of at least 0.5 cm of skin surrounding the wound edge over which no tincture of benzoin was applied to avoid the possible inflammatory effects of benzoin on the raw wound. No further treatments were applied to the wound for the duration of the experiment.
Treatment Groups
The mice were divided into 4 treatment groups, with each mouse serving as its own control:
Group I: The wound on one side of the animal was treated with FG (60 mg/ml) while the contralateral wound received no treatment. Both wounds were covered with Opsite™.
Group II: Diluted FG (1.0 mg/ml) was topically applied to the wound on one side while the contralateral wound received no treatment. Both wounds were covered with Opsite™.
Group III: FG (60 mg/ml) was topically applied over both wounds. The wound on one side was left uncovered while the contralateral wound was covered with Opsite™.
Group IV: No topical treatment was applied over the wounds. The wound on one side of the animal was left uncovered while the wound on the contralateral side was covered with Opsite™.
Wound Analysis
The animals were euthanized on Day 9 of the experiment. The wounds were excised down to the muscle layer, including a margin of 0.5 mm of unwounded skin, and were placed in buffered 10% formalin solution. The specimens were submitted to a histology laboratory for processing. Specimens were embedded in paraffin, and the midportion of the wound was cut in 5-μm sections. The slides were stained with hematoxylin and eosin, or with Masson's trichrome for histologic analysis.
Each slide was given a histological score ranging from 1 to 15, with 1 corresponding to no healing and 15 corresponding to a scar with organized collagen fibers (Table 2). The scoring scale was based on scales used by previous investigators. The criteria used previously were modified and were further defined to more precisely reflect the extent of: reepithelialization, degree of cellular invasion, granulation tissue formation, collagen deposition, vascularity, and wound contraction. The histologic score was assigned
TABLE 2 Criteria for Scoring of Histologic Sections Score Criteria 1–3 Epithelialization None to very minimal Cellular content None to very minimal (mainly inflammatory cells) Granulation tissue None to sparse amount at wound edges Collagen deposition None Vascularity None 4–6 Epithelialization Minimal (less than half of wound diameter) to moderate (more than half of wound diameter) Cellular content Predominantly inflammatory cells, few fibroblasts Granulation tissue None to thin layer at wound center, thicker at wound edges Collagen deposition Few collagen fibers Vascularity Few capillaries 7–9 Epithelialization Completely epithelialized; thin layer Cellular content More fibroblasts, still with inflammatory cells Granulation tissue 7, sparse at wound center, mainly adipose tissue underneath epithelium 8, thin layer at wound center; few collagen fibers 9, thicker layer; more collagen 10–12 Epithelialization Thicker epithelial layer Cellular content Predominantly fibroblasts Granulation tissue Uniformly thick Collagen deposition Moderate to extensive collagen deposited, but less mature when compared to collagen of unwounded skin margin Vascularity Moderate to extensive neovascularization 13–15 Epithelialization Thick epithelium Cellular content Fewer number of fibroblasts in dermis Granulation tissue Uniformly thick Dense, organized, oriented collagen fibers Few well-defined capillary systems
separately by at least three analysts. The code describing the wound treatment was broken after the scoring was completed by all observers.
Statistical Analysis
The values of the histological scores of the analysts were averaged and were expressed as the mean±standard error of the mean.
The paired t test was used for comparison of paired means in the different treatment groups. The analyses were performed using the RS/1 Release 3.0 statistical software package (BBN Software Products Corporation).
The sample mean differences were tested for analysis of variance using the Statistical Analysis Software (SAS) System.
Results
The Effect of FG on Wound Closure (Group I)
In Group I both wounds on each mouse were covered with Opsite™. Under these conditions, the topical application of FG with a protein concentration of 60 mg/ml to only one side of the animal resulted in statistically lower mean histological scores (3.06) for the FG side compared to the untreated wounds (5.26) (P<0.005) (Table 3).
TABLE 3 The Effect of FG (60 mg/ml) on Wound Closure (Group I) Treatment Histologic score N FG + Opsite ™ 3.06 ± 0.7 15 Opsite ™ alone 5.26 ± 2.21 15
The Effect of Dilute FG on Wound Closure (Group II)
In this group, both paired wounds which were covered with Opsite™, topical application of dilute FG (protein concentration of 1 mg/ml) resulted in a mean histological score (4.0) that was not statistically different from that for untreated wounds (4.36) (P=0.17) (Table 4).
TABLE 4 The Effect of Dilute FG (1 mg/ml) on Wound Closure (Group II) Treatment Histologic score N Dilute FG + Opsite ™ 4.00 ± 0.77 11 Opsite ™ alone 4.36 ± 0.67 11
The Effect of Opsite™ on FG-Treated Wounds (Group III)
In this group of paired wounds both treated with FG with a protein concentration of 60 mg/ml, the application of Opsite™ to one side resulted in a mean histological score (4.2) which was not statistically different from that for wounds which were left uncovered (4.93) (P=0.11) (Table 5).
TABLE 5 The Effect of Opsite ™ on Paired Wounds Treated with FG (Group III) Treatment Histologic score N Opsite ™ + FG 4.20 ± 1.93 15 FG but no Opsite ™ 4.93 ± 1.09 15
Effect of Opsite™ on the Closure of Paired Untreated Wounds (Group IV)
In this group of paired wounds which did not receive topical treatment of FG, application of Opsite™ to one side resulted in a significantly lower mean histological score (4.92), as compared to that for wounds which were left uncovered (6.31) (P<0.0005) (Table 6).
ANOVA of the treatment effects on sample mean differences was significant at <0.0001.
TABLE 6
The Effect of Opsite ™ on the Closure of Paired
Untreated Open Wounds (Group IV)
Treatment
Histologic score
N
Opsite ™ (no FG)
4.92 ± 1.26
13
No Opsite ™ (no FG)
6.31 ± 1.25
13
Discussion
The results of this study indicated that in mice (1) when applied over open wounds, FG at a concentration formulated for hemostasis (60 mg/ml) resulted in lower histological scores at Day 9 which indicated slower rates of wound healing compared to that of untreated wounds; (2) dilution of the FG protein concentration to 1 mg/ml resulted in a higher histological score at Day 9 which indicated a faster rate of wound healing; and (3) application of a semipermeable dressing (Opsite™) per se significantly retarded wound closure in this animal model by itself.
The total protein concentration of FG is an important variable when comparing the results of studies using FG. Beneficial effects of fibrin in promoting wound healing and tissue repair have been reported, but lower concentrations of fibrinogen have been used in the present studies than is commonly found in commercial preparations.
FG at a concentration of 60 mg/ml delayed wound closure (Group I). The total protein concentration of FG which is commercially available in Europe, after mixture of the fibrinogen and thrombin components, is 37.5 to 57.5 mg/ml. These data indicate that FG as presently formulated for hemostatic and adhesive indications retards healing when applied to open skin wounds. This effect may be due to (1) mechanical obstruction to the migration or proliferation of cellular elements that actively participate in the wound healing process, (2) mechanical inhibition of wound contraction or (3) a chemical inhibitory effect of one or more FG components on wound healing. Mechanical obstruction and inhibition of wound closure may be the more likely explanation, since at Day 9 there is persistence of a solid fibrinogen-based clot on the wound surface.
In order to help determine if this was the cause, the total protein concentration of FG was diluted to 1 mg/ml. Topical application of this dilute FG resulted in a histological score that was not significantly different from that for untreated wounds (Group II), suggesting that lower total protein concentrations do not significantly inhibit the wound healing process.
It is also worth noting that the mean histological score for covered wounds treated with the same concentration of FG (60 mg/ml) but belonging to different treatment groups (Groups I and III) had significantly different values (3.06 for Group I vs. 4.2 for Group III). These data demonstrated that animal to animal variation makes it difficult to derive definitive conclusions from different animals subjected to the same treatment variables because some animals may heal faster or slower than the others despite receiving the same treatment. This is reflected in the range of standard errors for the mean scores. For this reason each animal served as its own control, e.g. wounds in the same animal were compared to each other. By having the control wounds in the same animal as the test wounds, the effects of interanimal variability was minimized. These data also show that an adhesive dressing such as Opsite™ significantly delayed wound closure. It should be noted, however, that in partial thickness skin wounds in pigs the protein concentration of the FG does not appear to be related to the rate of wound healing.
B. Growth Factor-Supplemented FG on Wound Healing In Vivo.
The effect of HBGF-1B growth factor-supplemented FG on the rate of wound repair in diabetic mice was assessed. The methods used in this experiment were similar to those just described above. Two 6 mm full-thickness skin biopsies on the dorsal part of each of 6 test mice were filled with FG to which 5 μg of HBGF-1β had been added. Identical biopsies in six mice were left untreated, and in six control mice were filled with unsupplemented FG. After 9 days, all of the mice were sacrificed and histological preparations of 5 micron thick slices from each of the wounds and surrounding skin were prepared and stained with hematoxylin and eosin.
The extent of wound repair in each sample, which was not identified as to the treatment group from which it came, was “blindly” evaluated by each of three trained analysts, who assessed collagen deposition, reepithelialization, thickness of the granulation tissue and the density of inflammatory cells, fibroblasts and capillaries. Each sample was scored from 1 to 15, ranging from no to complete repair. The samples from the wounds treated with unsupplemented FG were consistently given the lowest scores and those from the untreated wounds or wounds treated with the growth factor-supplemented FG were given the highest scores.
EXAMPLE 13
FG as a Delivery Vehicle of Osteoinductive Substances In Vivo
Fibrin Sealant
Concentrated human TFC (Baxter Hyland Division, San Pedro, Calif.) and human thrombin (Baxter Hyland Division, Glendale, Calif.) were produced for the American Red Cross from screened fresh frozen pooled human plasma. Both components underwent viral inactivation using the solvent detergent method (New York Blood Center) during their production and were supplied in lyophilized form. After reconstitution with 3.3 ml of sterile water, the protein characteristics of the TFC solution were: total protein=120 mg/ml; fibrinogen=90 mg/ml; fibronectin=13.5 mg/ml; Factor XIII=17 U/ml; and plasminogen=2.2 μg/ml.
Human thrombin (1000 U vial) was reconstituted with 3.3 ml sterile water, and was serially diluted in 40 mM calcium chloride solution (American Regent Laboratories, Shirley, N.Y.) to a concentration of 15 U/ml. Human thrombin was used for preparing disks implanted which were onto calvarial defects.
Topical bovine thrombin (5000 U vial, Armour Pharmaceutical Co., Kankakee, Ill.) was reconstituted with 5 ml sterile water, and was serially diluted in 40 mM calcium chloride solution to a concentration of 15 U/ml. Bovine thrombin was used for preparing implants for intramuscular bioassay.
In practicing this embodiment of this invention the fibrinogen should be present at a concentration of 1 to 120 mg/ml FG, more preferably from 3 to 60 mg/ml FG, most preferably from 10 to 30 mg/ml FG. DBM should be present at an approximate concentration of about 1 to 1000 mg/ml FG, more preferably from 50 to 500 mg/ml FG, most preferably from 300–500 mg/ml FG. The particle size of demineralized bone powder should be from 0.01 to 1000 microns, preferably from 20–500 microns and most preferably from 70–250 microns. The osteoinductive growth factor(s) or BMPs should be present at a concentration(s) of about 1 to 100 μg/ml wherein the concentration(s) is effective to accomplish its desired purpose. Growth factors which may be used as osteoinductive substances in this embodiment include, but are not limited to: osteogenin (BMP3); BMP-2; OP-1; HBGF-1; HBGF-2; BMP 2A, 2B and 7; FGF-1; FGF-4; and TGF-β. In addition, drugs, such as antibiotics, can be used to supplement the TS for use in bone repair.
Implant Preparation
Rat DBM was prepared as follows. The epiphyses of the long bones of rats were removed leaving only the diaphyses behind. The diaphyses were split, if necessary, and the bone marrow was then thoroughly flushed with deionized water (Milli-Q Water Purification System™, Millipore Corporation, Bedford, Mass.). The diaphyses were then washed at room temperature. At 4° C., 1000 mls of deionized water was added to 100 g of bone. The mixture was stirred for 30 minutes and the water was decanted. This step was repeated for two hours.
At 4° C., one liter of cold absolute ethanol (Quantum Chemical Corporation, U.S.I. Division, Tuscola, Ill.) was added for every 100 g of bone. After stirring for 15 minutes, the ethanol was decanted. This was repeated four times for a total of one hour's duration.
Under a fume hood, 500 ml of diethyl ether (Mallinckrodt Speciality Chemicals, Paris, Ky.) was added to the bone to cover it. This was stirred gently for 15 minutes and the ether was then decanted. An additional 500 mls of ether was added to the bone and the mixture was stirred for 15 minutes. The ether was again decanted. The bone was left under the fume hood for the evaporation of the ether to occur. Defatted bone can be stored indefinitely in an ultralow freezer (−135° C.).
The bone was then milled to make bone powder. The powder was sieved and 74 to 420 micron size particles were collected.
Ten gram aliquots of the bone powder were placed in 250 ml centrifuge bottles. Eighty mls of 0.5 N HCl was added to each bottle slowly in order to avoid frothing. The contents of each bottle were then stirred gently. After 15 minutes, an additional 100 mls more of 0.5 N HCl was added to each bottle over the course of 10 minutes. The bottles were then stirred gently for an additional 35 minutes. The total time that the powder was in the HCl did not exceed one hour.
Each mixture was then spun in a centrifuge at 3000 rpm at 4° C. for 15 minutes. The pH of the supernatant was then checked. If the pH was greater than 2, the supernatant was poured down a chemical sink without disturbing the pellet(s). If the pH of the supernatant was less than 2, the supernatant was poured off into a hazardous waste container. If the pellet(s) were loose, the centrifuge time was increased to 30 minutes. These steps were repeated until the pH of the supernatant was equal to 0.5 N HCl.
The pellets were then washed with 180 mls of deionized water by stirring to produce an even suspension. The suspension was then centrifuged for an additional 15 minutes. The supernatant was then decanted as before. The washing was repeated until the pH of the supernatant equaled the pH of the deionized water.
The pellets were then frozen at −180° C. in a freezer. They were then lyophilized using standard procedures.
Disk-shaped implants 1 mm thick and 8 mm in diameter were produced using a 4-piece aluminum mold ( FIG. 14 ). Twenty-five mg of rat DBM powder was added into the mold chamber. Thirty μl of TFC was then pipetted onto the DBM and mixed until the DBM had absorbed all of the solution. The concentrations of TFC which were used were 10, 20, 40, 80, or 120 mg/ml. Thirty μl of thrombin solution (15 U/ml in 40 mM calcium chloride solution) was then added to the DBM-TFC complex, was mixed, and was compressed into a disk-shape using a piston-shaped lid. It was determined that 25 mg of DBM powder had a volume of 20 μl. After DBM had been added to the FG, the final protein concentrations were as follows:
TABLE 7
FG, Total
TFC
Thrombin
DBM
protein conc.
(mg/ml)
(μ/ml)
(mg)
(mg/ml)
120
15
25
45
80
15
25
30
40
15
25
15
20
15
25
8
10
15
25
4
Disk implants composed of DBM alone or FG alone (4, 8, 15 and 45 mg/ml total protein concentrations) were likewise made using the same mold.
Fifty mg of DBM was poured into an aluminum mold, to which 60 μl of TFC was then added to the DBM and mixed until fully absorbed. Sixty μl of thrombin was then added to the DBM-TFC complex, mixed and compressed into a disk-shape with a diameter of 1 cm and a thickness of 2 mm using a piston-shaped lid. The disk was then cut manually into the desired shape (triangle, square or donut).
For the intramuscular bioassay experiment, implants were placed in a sterile nylon bag having a mesh size of 70 microns and measuring 1 cm×1 cm.
Animals
Male Long-Evans rats were obtained from Charles River Laboratories (Wilmington, Mass.). For the intramuscular bioassay, 28 to 35 day old rats were used. Three month old rats were used for the craniotomy experiment.
Surgery
The animals were anesthetized with a mixture consisting of 10 ml ketamine hydrochloride (Vetalar, 100 mg/ml, Parke-Davis, Morris Plains, N.J.), 5 ml xylazine (Rompun, 20 mg/ml, Mobay Corporation, Shawnee, Kans.), and 1 ml physiologic saline (0.9% NaCl), at a dose of 0.1 ml per 100 gm body weight, administered intramuscularly. The operative site of the animal was prepped with 70% alcohol solution, followed by povidone-iodine solution. The surgical procedure was then performed using aseptic technique.
Intramuscular Bioassay. A midline ventral incision was made and a space was created between the pectoralis muscles with blunt dissection. A nylon envelope containing the designated experimental material was inserted into the intramuscular space and secured with a 3-0 Dexon suture ( FIG. 15 ). The same procedure was then repeated at the contralateral side. The skin was then closed with staples. The implants were harvested after four weeks, were x-rayed and were prepared for histology.
Disk-shaped implants were placed randomly and consisted of the following: DBM alone (n=12); FG alone at different concentrations (4 mg/ml, n=14; 8 mg/ml, n=3; 15 mg/ml, n=3; and 45 mg/ml, n=12), and DBM-FG complex (4 mg/ml, n=12; 8 mg/ml, n=12; 15 mg/ml, n=12; and 45 mg/ml, n=12). There were four each of the square-, triangle- and donut-shaped implants.
Craniotomy Procedure. A linear incision was made from the nasal bone to the mid-sagittal crest. Soft tissues were reflected gently and the periosteum was dissected from the craniotomy site (occipital, frontal, parietal bones). An 8-mm craniotomy was prepared with a trephine in a slow-speed rotary handpiece using copious saline irrigation as needed. The calvarial disk was dissected free while avoiding dural perforations and superior sagittal sinus intrusion. The 8-mm calvarial defect was either left untreated as control or filled with a 1×8-mm DBM or DBM-FG disk ( FIG. 16 ). The skin was then closed with skin staples.
Following surgery, each rat was identified by ear punches and returned to its cage where they were ambulatory within 2–3 hours.
The first set of calvarial implants consisted of DBM alone (25 mg, n=3) or DBM in a FG matrix (15 mg/ml, n=2; 30 mg/ml, n=3; and 45 mg/ml, n=3), and were retrieved after 28 days. The second set of calvarial implants consisted of 25 mg DBM in a 30 mg/ml FG matrix and were retrieved at different postoperative times (28 days, n=10; 3 months, n=9; and 4 months, n=5).
Retrieval of Implants
At the indicated times, the rats were euthanized in a carbon dioxide chamber. A skin incision was made around the experimental recipient bed (i.e., pectoralis major or calvaria) and the soft tissues were reflected from the recipient beds. In orthotopic sites, the craniotomies with 3–4 mm contiguous bone were recovered from the fronto-occipito-parietal complex. In heterotopic sites, sharp and blunt dissection was used to recover the implanted nylon envelopes.
Radiography
The implants were radiographed using X-OMATL™ high contrast Kodak x-ray film (Eastman Kodak Company, Rochester, N.Y.) in a Minishot Benchtop Cabinet x-ray system (TFI Corporation, West Haven, Conn.) at 30 kvp, 3 Ma, and 10 seconds. Gray-level densities of intramuscular and craniotomy site radiographs were analyzed using a Cambridge 920 Image Analysis System™ (Cambridge Instruments Limited, Cambridge, England).
Histological Analysis
All retrieved specimens (soft and hard tissues) were immediately placed into appropriately labeled vials containing preservative solution and were submitted to a histology laboratory for processing. Histologic specimens were 4.5 micrometer-thick sections through the coronal diameter. For each recipient site, one section was prepared with hematoxylin and eosin stain (for photomicrography and examination of cell and stromal detail) and the other section was prepared with a von Kossa stain.
Results
Radiography of Intramuscular Plants
All DBM disks displayed radio-opaque images. Forty-five out of 48 implanted DBM-FG disks (93.75%) were radio-opaque. All DBM-FG disks, regardless of protein concentration (445 mg/ml) induced radio-opacity ( FIG. 17 ). Radio-opacity measurements of some DBM disks ( FIG. 17 ) were higher than DBM-FG disks but the other measurements were well within the range of measurements for DBM-FG disks. Thirty out of 32 FG disks which were not supplemented with DBM (93.75%) did not develop radio-opacity.
DBM-FG disks in the form of squares, triangles or donuts were also markedly radio-opaque as compared to FG disks which were not supplemented with DBM. The original shapes of the implants were generally retained.
Histology of Intramuscular Implants
The intramuscular bioassay was positive for DBM and DBM-FG implants, as evidenced by formation of ossicles with a central cavity filled with marrow and resorption of previously implanted DBM particles.
Radiography of Calvarial Implants
X-rays showed DBM implants in a FG matrix to be generally more radio-opaque than DBM implants alone or untreated controls. There was no marked discernible difference between different concentrations of FG used to deliver DBM. The radiographs of untreated 8-mm diameter calvaria defects showed a negligible amount of radio-opacity.
The second set of calvarial implants using DBM in 30 mg/ml FG matrix showed markedly increased radio-opacity within the craniotomy wounds of 3 or 4 month-old calvaria over 28 day calvaria ( FIG. 18 ).
Histology of Calvarial Implants
Non-treated 8 mm craniotomy wounds showed only fibrous connective tissue developing across the craniotomy wound ( FIGS. 19A and B). Histology of DBM implants showed DBM particles to be scattered all over the field. Some DBM particles migrated over and under the edges of host bone ( FIG. 20 ). Most DBM particles were, however, within the confines of the craniotomy wound and were surrounded by loose connective tissue that was well vascularized. Active resorption of DBM by osteoclasts was noted. A lot of DBM particles were also noted to be populated by live cells. New osteoid and bone laid down by osteoblasts were quite evident.
The histology of DBM implants in a FG matrix showed DBM particles localized within the craniotomy wound, surrounded by much denser and more cellular connective tissue ( FIGS. 19 and 20 ). Osteoid matrix and bony trabeculae formation were quite evident. More bone marrow was noted to have formed in craniotomy wounds implanted with DBM-FG disks than with DBM implants alone. There was also greater neovascularization with DBM-FG disks than with DBM implants alone or untreated controls. Osteoregeneration was evident at all concentrations of FG used to deliver DBM.
Discussion
The natural biocompatibility and biodegradability of FG are characteristics that make it an ideal delivery vehicle for DBM and BMPs. FG facilitated the shaping of DBM into the desired form to fill bony defects, maintained DBM within the defect, and may have been synergistic with DBM. Furthermore, soft tissue prolapse did not occur and bony contour was maintained. DBM-supplemented FG possessed an appropriate microarchitecture, biodegradation profile and release kinetics to support osteoblast recruitment and osteoregeneration.
Overall, the data indicated that DBM delivered in FG at any of the tested FG protein concentrations induced as much bone formation as the DBM did alone. Moreover, when DBM was configured with FG to a particular pre-operative form, the induced bone closely retained the original shape postoperatively.
Since the shape of the DBM-FG matrix determined the morphology of the newly formed bone, when possible, the DBM-FG matrix should be made of a predetermined shape. However, the DBM-FG matrix in liquid form can be delivered or injected into an irregularly shaped defect where it will polymerize and encourage bone formation in the DBM-FG-filled area.
EXAMPLE 14
The Release of Antibiotics (AB) from FG and Increased Longevity of the AB-Supplemented FG
A. Preparation of the AB-FG
1. TET Free Base
Three-and-one-half ml of water for injection was injected into a vial of lyophilized human topical fibrinogen concentrate (TFC), supplied by The American Red Cross. The protein concentration of the resulting solution was approximately 120 mg/ml.
Freeze-dried thrombin concentrate, supplied by The American Red Cross/Baxter-Hyland, Inc., Glendale, Calif., was reconstituted with 3.5 ml of a 40 mM solution of calcium chloride prepared in water for injection. The resulting solution contained approximately 250 U/ml.
TET-FG was formulated by mixing the desired weight of TET with 1 ml of reconstituted TFC solution and with 1 ml of reconstituted thrombin solution in the presence of injection quality calcium chloride (purchased from American Reagent, Shirley, N.Y.). The TET was in the free base form and was purchased from Sigma Chemical Company (St. Louis, Mo.). The TET-FG was formed by mixing TFC and thrombin through a Duoflo™ dispenser (Hamaedics, Calif.) onto a Millipore membrane in a 12 mm diameter Millipore culture plate (Millipore Corporation, Bedford, Mass.). The mixture was allowed to set for one hour at 22° C. Six mm diameter disks containing the TET-FG and the Millipore membrane were cut from the latter using a 6 mm punch biopsy. The TET-FG-containing disks were used for the TET release studies.
The release of TET from the TET-FG into phosphate buffered saline (PBS) or saliva was measured using 24-well cell culture plates (Corning Glass Works, Corning, N.Y.) under two different sets of conditions. In one condition, the static mode, 2 ml of PBS or 0.75 ml of saliva was replaced daily in the 24-well cell culture plates. In the other condition, the continuous exchange mode, TET release from the TET-FG was measured with PBS having been exchanged at a rate of approximately 3 ml per day. The samples were stored at −20° C. until analyzed. The saliva had been collected from 10 different people, had been pooled, and clarified by centrifugation at 5000 g. It was then filtered through a 0.45 μm pore sized membrane and was stored at 4° C. for daily use.
In order to measure the concentration and biological activity of the TET which had been released from the TET-FG disks, the eluted TET was thawed and was analyzed spectrophotometrically at 320 nm and/or biologically by the inhibition of E. coli growth on agar plates. To calibrate these assays, standard curves covering TET concentrations of from 0 to 50 and 0 to 500 μg/ml, respectively, were used.
2. Ciprofloxacin HCl (CIP)-, Amoxicillin (AMO)- and Metronidazole (MET) Supplemented FG.
FG containing CIP HCl, AMO or MET were prepared as before for TET. To monitor the release of these AB from the corresponding AB-FG into the immediate environment, the AB-FG disks were placed in individual wells in a 24-well cell culture plate and were covered with 2 ml of PBS that was collected, replaced daily and stored at −20° C. as before, until analyzed. The concentrations of CIP, AMO and MET in the eluates were measured spectrophotometrically at 275, 274 and 320 nm, respectively, and were compared to standard curves containing 0 to 50 ug/ml of the corresponding AB.
B. Structural Integrity of AB-FG
The maintenance of the structural integrity of the FG and the TET-FG disks was estimated by visual observation and physical inspection by “poking” the disks with a fine spatula. The porous membrane which had been cut out while making the disks remained attached to the TET-FG and was used to help position the disks during the evaluation of their structural integrity. Pictures of top and lateral views of the disks were also taken and were used in the evaluation.
The structural integrity of FG and TET-FG were measured under both sterile and non-sterile conditions. For the non-sterile experiments, the PBS and saliva were stored frozen until analyzed. For the sterile experiments, the same procedure was used except that the entire process was run under sterile conditions. The sterility of the system was tested by incubating 0.2 ml of sample and 2 ml of broth at 37° C. and the turbidity of the broth was monitored for 48 hours. Lack of turbidity indicated sterility of the system. The stability of the CIP-, AMO-, and MET-FG were studied as above but under non-sterile conditions only.
C. In Vitro Antimicrobial Activity of AB Released from AB-FG
The antimicrobial activity of the AB released from the AB-FG was estimated by measuring the diameters of the zones of inhibition generated by the eluate from the 6 mm diameter disks from the daily collected PBS or saliva surrounding the AB-FG. The eluates from unsupplemented FG served as controls. AB solutions of known concentration were used as standards. E. coli cultured on agar plates were used to measure the AB activity of the released TET, CIP and MET. To make the culture plates, 100 μl of the bacterial cell suspension, containing approximately 10 8 cells/ml, was mixed with 3 ml of top agar at 50° C. and immediately poured onto the plate hard, bottom agar to make a uniform layer of cells. The plates were incubated at 37° C. for 18 hours.
Results
A. TET
1. TET Release Data
The release of TET from TET-FG disks into the surrounding PBS in the “static” experiments was measured spectrophotometrically by determining the TET concentration achieved in the 2 ml of PBS which was replaced daily. The TET concentrations which were obtained for different amounts of TET that had been incorporated into TET-FG are shown in FIG. 23 . At TET concentrations in the TET-FG of less than 50 mg/ml, the release of TET was completed in five days or less. However, the release of TET from TET-FG disks which contained TET concentrations of 100 and 200 mg/ml occurred for approximately two weeks, and more than three weeks, respectively. The structural integrity of the TET-FG disks was preserved for three to five weeks. These results demonstrated that the TET release was independent of the FG degradation and that the rate of TET release depended on the amount of TET which remained in the TET-FG disks.
The spectrophotometric data which were collected in the continuous exchange experiment are shown in FIG. 24 . These data indicate that a continuous TET release from a TET-FG disk which originally contained a TET concentration of 100 mg/ml FG occurred over a two week period. The FG disk retained its structural integrity during this two week period, infra. The TET release data obtained in the continuous mode experiment also indicated that the rate of TET release opportunity depended on the concentration of TET which remained in the TET-FG disk.
While not wishing to be bound by theory, it is believed that the initial high TET concentrations observed in these experiments were probably a consequence of the diffusion of TET from at or near the disk's surface. That is, as the TET “trapped” at these locations was exhausted, the rate of solubilization and/or diffusion decreased in a fashion that was most probably determined by the TET concentration gradient and by the shape or configuration of the FG.
Temperature and FG protein concentration also played a role in determining the TET diffusion rate from the TET-FG disks (see Examples 13 and 14), but these two parameters were kept constant in these experiments.
The release of TET into saliva from TET-FG containing 50 and 100 mg/ml of TET was measured in static experiments by determining the TET concentration in 0.75 ml of saliva that was replaced daily. These results ( FIG. 25 ) are similar to those obtained in PBS except that the concentration of TET was higher, most probably reflecting the smaller volume of saliva which was used to collect the released TET. In addition, the presence of TET in the FG matrix again unexpectedly prolonged the structural integrity of the TET-FG matrices for at least 15 days compared to that for the control FG disks which had begun to decay by 9 days and were almost completely decayed by 15 days ( FIG. 26 ).
2. TET Antimicrobial Data
The antimicrobial effects on E. coli growth of several TET concentrations in PBS are shown in FIG. 27 . The lowest TET concentration detectable by this method was approximately 5 μg/ml. These results clearly indicate that the released TET has antimicrobial activity. These TET data corroborate those obtained by spectrophotometry and indicate that the amount of TET incorporated into the FG determines the TET concentration in the solution surrounding the TET-FG. These data also demonstrate that the amount of TET in the FG can be tailored to maintain the desired TET concentration in the medium surrounding the TET-FG at or above the minimum desired TET concentration.
3. TET-FG Matrix Longevity
The longevity of control FG and AB-FG disks was evaluated by visual assessment of the disks. The porous membrane, cut during the making of the disks, remained attached to the FG and helped to position the disks during their integrity evaluation. Top views of disks containing no TET (controls), and 50 or 100 mg of TET per ml of FG are shown in FIG. 26 at days 0, 9 and 15. This figure shows typical results, namely, the FG control disks were degraded within two weeks whereas the TET-FG disks remained intact, or nearly so, for 15 days. In additional experiments TET-FG disks remained intact or nearly so for at least five weeks (date not shown). No significant change in the FG longevity was observed between sterile and non-sterile TET release experiments.
B. CIP, AMO and MET Data
1. CIP, AMO and MET Release Data
The antibiotic released from CIP-, AMO- and MET-FG is shown in FIG. 28 . CIP was released at an apparent constant rate for approximately 4 weeks and then the rate decreased gradually for approximately one more week. The release of AMO and MET was complete within 3 days.
2. CIP and MET Antibacterial Activity
The antimicrobial activity of released CIP and MET (data not shown) parallels the profiles determined spectrophotometrically for identical AB-FG disks.
3. Supplemented-FG Matrix Longevity
The results for CIP-FG were similar to those for TET-FG. The results for AMO- and MET-FG were similar to those obtained for the FG control. No significant change in the FG longevity was observed between sterile and non-sterile experiments.
Discussion
The results demonstrated that poorly water soluble forms of CIP and TET provide a combination of factors that increase significantly the maximum AB load, release period and longevity of the FG matrix into which they are mixed. Alternatively, the FG disks can be stabilized by immersing them in solutions of AB such as TET or CIP.
The results also clearly showed that the AB delivered by AB-FG preserved its antimicrobial activity as demonstrated by the inhibition of E. coli growth. These results demonstrated that TET and CIP supplementation of FG and other TS can overcome the degradation of FG as a limiting factor in drug delivery therefrom. That is these ABs stabilized the FG so that their release periods and the released AB concentrations can be controlled using AB concentrations in the FG. Using these procedures TET and CIP can be loaded into FG and their release can be controlled for a period of days or weeks at effective antimicrobial concentrations.
The TET- and CIP-induced FG stabilization can be exploited for controlling the total release time not only for these ABs, but also for other drugs or “supplements” added to FG whose release rate and/or total release duration depends on the integrity of the FG matrix.
These results have clinical applications in periodontal and other conditions where FG can serve as a localized drug delivery system. The TET- or CIP-induced FG stabilization can be exploited for controlling the total release time of TET, CIP and other drugs or supplements which have been added to the TET-FG or CIP-FG matrices.
EXAMPLE 15
Effect of Temperature on the TET Release Rate from TET-Supplemented FG
FG was supplemented with 50 mg/ml of TET free base and was shaped as 6×2.5 mm disks for this study. The protein concentration of FG was adjusted to 60 mg/ml. The disks were placed in 2 ml of PBS, pH 7.3 and were allowed to stand at 4, 23 and 37° C. To wash the disks, the PBS was replaced every 10 minutes, 6 times, with 2 ml of fresh PBS. Thereafter the PBS was replaced every hour for 4 hours. The TET concentrations in the collected samples were determined spectrophotometrically against a standard curve as before.
The results demonstrated that the rate of TET release was proportional to the temperature ( FIG. 29 ).
EXAMPLE 16
Effect of FG Protein Concentration on the TET Release Rate from TET-Supplemented FG
FG supplemented with 1 mg/ml of TET HCl solution was prepared and was shaped as 6×2.5 mm disks for this study. The protein concentration of the FG was adjusted to 60, 30 and 15 mg/ml. Each disk was placed in 3 ml of distilled water. The water was replaced with the same volume of water every 10 minutes for a total of one hour. The TET concentration in the collected samples was determined spectrophotometrically against a standard curve as before.
The data ( FIG. 30 ) show that the TET release rate was highest from the FG with the lowest total protein concentration and vice versa. That is, the TET release rate was inversely proportional to the FG protein concentration.
EXAMPLE 17
In Vivo Antimicrobial Activity of AB Released from AB-Supplemented FG
To test the antimicrobial activity of TET and CIP released from TET- and CIP-FG, the capacity of these AB-supplemented FGs to protect mice from induced peritonitis was evaluated. Experimentally, at day 1, each one of 5 animals per group were injected intraperitoneally with 0.5 ml PBS (Group-I), FG (Group-II), TET-FG (Group-III) or CIP-FG (Group IV). FG and AB-FG was administered using a Hamaedics dispenser containing 0.25 ml of TFC at 120 mg/ml and 0.25 ml of human thrombin at 250 U/ml. In the case of TET- and CIP-FG, the thrombin solution contained 50 mg of the respective AB. At day 2, all the animals were injected intraperitoneally with 2×10 8 (Experiment 1) or 4×10 8 (Experiment 2) colony forming units (cfu) of S. aureus 202A. Results: (Experiment 1, Experiment 2. Animals surviving at 48 hours after infection): Group I, 0 and 1 survivors; Group II, 3 and 1; Group III, 3 and 5; and Group IV, 5 and 4 survivors. Most survivors lived through the duration of the experiment (2 weeks) but some died or were intentionally killed because they were sick.
These data demonstrated that TET-FG and CIP-FG protected mice from death caused by S. aureaus 202A for at least 48 hours after the administration of the AB-supplemented FG.
EXAMPLE 18
Therapeutic Applications of Supplemented Fibrin Sealant Compositions
The development of ultrathin microfiberoptic endoscopes has offered the laryngologist unique access to the limited spaces of the temporal bone and skull base. While diagnostic middle ear endoscopy is well documented (Edelstein, D. R. et al., Am. J. Oto. 15:50–55 (1994); Poe, D. S. et al., Laryngoscope 102:993–996 (1992); Poe, D. S. et al., Am. J. Oto. 13:529–533 (1992); Balkany & Fradis, Am. J. Oto. 12:4648 (1991)), therapeutic microendoscopy offers the exciting advantages to the patient of minimal invasiveness, reduced patient morbidity and lower hospital cost. Microendoscopes of constantly shrinking diameters yield images of good quality and resolution. Coupled to a laser and fibrin sealant applicator, several new surgical applications in the middle ear and skull base are now feasible. Potential therapeutic applications were derived from the fibrin sealant's mechanical properties in soft tissue repair and use as a sustained delivery vehicle for pharmaceuticals and biologic growth factors. Possibilities include ototopical aminoglycoside therapy, using for example gentamycin for the treatment of Ménière's disease, transeustachian CSF leak prophylaxis and tympanic membrane repair.
Preliminary antibiotic “release profiles” were obtained using pooled fibrin sealant (American Red Cross, Rockville, Md.), and either amoxicillin and metronidazole as “water soluble” agents, or tetracycline and ciprofloxacin in the “low solubility” category. For this procedure, four human head specimens were preserved and underwent latex vascular injection using the fresh tissue cadaver protocol actively in progress in the Naval Medical Center San Diego, San Diego, Calif. (The fresh tissue cadaver protocol is advantageous in preserving the specimens without loss of “fresh tissue” qualities.)
Both fiberoptic and rigid systems were used as provided by Xomed Corporation (Jacksonville, Fla.). The Alphascope 8 model was a flexible microfiberoptic endoscope with an outside diameter of 0.8 mm and a 115 degree flexible tip which provides a field of view of 65° with 1.5–15 mm depth of observation. The fiberoptic cable was composed of 3,000 pixels and provides 10 cm of insertion length. The Alphascope 12A model was a rigid endoscope with an outside diameter of 1.2 mm and an obliquely angled shaft of 25° and tip of 45° which provided a field of view of 65° with 2–20 mm depth of observation. The fiberoptic cable was composed of 6,000 pixels and provided 8 cm of insertion length. A 0.28 mm KTP laser (Laserscope, Palo Alto, Calif.) was used for all laser applications.
Limited-sink conditions were created using 6×3 mm fibrin sealant discs mixed with a set concentration of antibiotic. Concentrations in the eluate were measured on a daily basis (μg/ml) and evaluated over time to develop the “release profile” in vitro.
A duo-flow catheter was designed specifically to facilitate endoscopic application of fibrin sealant, having a 0.75 mm inner cannula with a 1.5 mm outer cannula. The 1.5 mm outer diameter allowed coupling to a microfiberoptic endoscope for access to the middle ear space, eustachian tube and cranial cavity. A “coaxial,” recessed tip allowed continuous tissue sealant application under visual guidance without clotting of the delivery ports.
Microendoscopic and Laser Techniques
Initial procedures were performed on human temporal bone specimens to document the feasibility of microendoscopic work within the middle ear and temporal bone. Both transtympanic as well as transeustachian tube routes were used to access the middle ear. All surgery in the posterior cranial fossa was performed through “keyhole” incisions in the posterior fossa dura through a suboccipital approach. Procedures utilized standard otologic equipment.
Coupled with the KTP laser, surgical manipulation was safely achieved around the oval window, to include lysis of adhesions and stapedotomy. Through a “keyhole” retrosigmoid approach, the flexible endoscope was introduced into the posterior cranial fossa with ready identification of the 7–8 nerve complex. When a comfortable level of technical competence was reached, the KTP laser was successfully employed for vestibular nerve section in 6 cadaver specimens without structural damage to neighboring neurovascular structures. Although difficulty was encountered in gauging the depth of vaporization in the first two specimens with damage apparent to the anteriorly located facial nerve, the problem was resolved with refinement of the technique and a change in the laser angle. The duo-flow catheter was attached to the endoscope when using the KTP laser to suction laser plume.
Fibrin Sealant Delivery
Coupled to a microfiberoptic endoscope, the Duo-Flow catheter (Hemaedics Corp., Malibu, Calif.) was used to deliver antimicrobial composition-supplemented fibrin sealant under direct view to the eustachian tube and middle ear space. Several routes of delivery were used including transtympanic, transeustachian tube and transmastoid through the facial recess. Successful “sealing” of the middle ear cavity, eustachian tube and mastoid cavities was achieved with each method of delivery. Fibrin sealant was noted to persist in these “static” specimens for over one week following application.
Tetracycline release profiles from the fibrin sealant disks showed a prolonged decay pattern in excess of three weeks. Concentrations above therapeutic Minimum Inhibitory Concentrations (MICs) remained for up to 42 days. Fibrinogen concentrations ranging from 20–76 mg/ml had little effect on the release profile of ciprofloxacin.
This demonstration of a sustained-release capacity of fibrin sealant demonstrated the great potential of the supplemented fibrin sealant composition as a therapeutic delivery system. On the antimicrobial level, topical application of fibrin sealant allows long-term delivery of antibiotic doses at many times the current minimal inhibitory concentration, often avoiding side effects observed in a systemic therapy. In particular, when coupled with the laser, microendoscopic surgery using a fibrin sealant localized-release “bioreservoir” offers great potential in the treatment of a broad spectrum of otolaryngic disorders ranging from ototopical amino-glycoside treatment of Ménière's disease to laser nerve section and topical antimicrobial therapy of acute and chronic sinusitis and otitis.
EXAMPLE 19
Sustained Release of Antimicrobial Compositions from Fibrin Sealant
Fibrin sealant (FS) disks were made by the enzymatic conversion of fibrinogen to fibrin by thrombin, and subsequently cross-linked by Factor XIII. Briefly, 100 mg of human Topical Fibrinogen Complex (TFC, American Red Cross, Rockville, Md.), containing 76% fibrinogen and Factor XIII, was combined with 10 mg human thrombin (American Red Cross, Rockville, Md.) and 0.9 ml 40 mM calcium chloride solution. The crosslinking fibrin clot was quickly placed into a 20×10×3 mm mold and pressed to form a slab. FS disks were then punched from the slab using a 6 mm biopsy punch. Following the same procedure, antibiotics were mixed with the lyophilized TFC and thrombin prior to hydration to form antibiotic-impregnated FS (AB-FS) disks. Tetracycline free-base, ampicillin free-acid and ciprofloxicin hydrochloride (Sigma Chemical Co., St. Louis, Mo.) were added separately as 345 mg to the TFC and thrombin prior to calcium chloride addition (final fibrin concentration was 76 mg/ml; final antibiotic concentration was 50 mg/disk).
Antibiotic release was measured in vitro under two extreme conditions, “limited sink” and “infinite sink.” Under limited sink conditions, FS and AB-FS disks were placed individually into wells of a 24-well tissue culture plate with two ml of phosphate buffered saline (PBS, pH 7.4). Tissue culture plates were left at 37° C. without agitation. The total volume of PBS was exchanged daily and the eluates evaluated for antibiotic content. Under infinite sink conditions, FS and AB-FS disks were placed individually into 50 ml conical centrifuge tubes with 45 ml PBS and agitated by inversion (20 times/min). All tubes were maintained at 37° C. The total volume of PBS was exchanged daily and the eluates evaluated for antibiotic content.
Antibiotic concentrations were calculated from linear standard curves of optical density versus concentration (0–200 ug/ml). Tetracycline samples were evaluated spectrophotometrically at 340 nm. Ampicillin was measured by first reacting 0.1 ml of the eluate sample with 2.9 ml BCA reagent (Pierce Chemical Co., Rockford, Ill.) for 30 min at 37° C. The resulting colored product was measured at 560 nm. Ciprofloxicin samples were evaluated directly at 340 nm.
To evaluate antibiotic release in vivo, tetracycline (TET)-supplemented FS disks were implanted into mice at two different locations. Male BALB/c mice (20–25 g) were anesthetized for the subcutaneous (s.c.) or intraperitoneal (i.p.) implantation of disks. Incision sites were closed with resorbable sutures and stainless steel clips. Disks were removed at 2, 7, 14, 21 or 28 days post implantation and enzymatically digested with 0.1% trypsin/0.4 mM EDTA at 37° C. for 4–7 days. TET concentrations of the lysates were measured as above to determine the mass of TET remaining in disks after in vivo incubation.
To assess the bioavailability of the antibiotic in TET-FS disks, TET-FS disks were placed into test tubes containing a log phase culture of S. aureus (1×10 7 CFU/ml). Cultures with FS disks containing no antibiotics served as controls. All cultures were incubated at 37° C. for 10 hr. Bacterial samples (0.1 ml) were serially diluted and plated onto nutrient agar to determine the viable bacterial count during the incubation with the disks. An unmanipulated culture was also monitored for comparison.
The elution profiles for the three antibiotics evaluated under limited sink conditions are presented in FIG. 31A . After an initial burst of antibiotic release, the freely water soluble ampicillin eluted completely from the supplemented FS matrix within 7 days. This contrasts the elution profile of tetracycline free-base which demonstrated a slowly decreasing, steady release over 42 days. Tetracycline elution at day 42 was a sustained, anti-microbially effective amount, 0.03–0.04 mg/ml. The release kinetics for ciprofloxicin parallelled those of tetracycline; although, data were only collected for 14 days. The elution profile for infinite sink conditions demonstrated an enhanced release of antibiotics during the first 7 days for all three antibiotics compared with limited sink conditions. Otherwise the elution profiles paralleled those observed for the limited sink conditions.
Release of tetracycline in vivo was measured by calculating the antibiotic remaining in AB-FS disks after 2, 7, 14, 21 or 28 days of in vivo implantion. The data are presented in FIG. 31B (combined with in vitro data) and show that the elution profile for TET-FS disks parallels the elution profile of the limited sink model in vitro. After 14 days in vivo, TET-FS disks still contained 50% of the starting concentration with no difference observed between the two sites (˜20% i.p. at day 28). These data demonstrate that both the s.c. and the i.p. sites facilitated the long-term delivery of TET from the TET-FS disks, and that the in vitro experiments were highly predictive of the demonstrated in vivo therapeutic effect.
Antibacterial activity was determined by the ability of TET-FS disks to inhibit growth of a S. aureus culture in vitro ( FIG. 31C ). TET-FS disks significantly inhibited bacterial growth in the 10 hr of study as compared with FS disks alone. Release of tetracycline and ciprofloxicin from FS disks was long term in both in vitro models demonstrating the correlation between the long term delivery of antibiotics and solubility. Antibiotics of relatively lower solubility were consistently released over longer time periods than highly soluble preparations. The delivery kinetics in vivo resemble those of the limited sink model suggesting a limited flow of body fluids at the s.c. and i.p. sites of delivery. Supplemented FS disks were shown to provide long-term delivery of concentrations of antibiotic sufficient to effectively inhibit bacterial growth, demonstrating that FS is an ideal, biocompatible, resorbable delivery system capable of releasing efficacious localized doses of antibiotic over an extended period of time.
EXAMPLE 20
Long Term Site-Directed Delivery of Cytotoxic/Antiproliferative Drugs from FG
The fibrinogen was solubilized with sterile water or, for one group with water saturated with 5-FU at a concentration of 17 mg/ml. Thrombin solutions were made with sterile water, and then were diluted in 40 mM CaCl 2 to a concentration of 15 U/ml, or Thrombin was dissolved in 40 mM CaCl 2 saturated with 5-FU in a concentration of 17 mg/ml.
Control FG clots did not contain 5-FU and were produced by mixing 200 μl of TFC solution (at 60 mg/ml) with 200 μl of Thrombin solution (at 15 U/ml) and allowing 20 minutes to polymerize. These clots were made in 12 by 75 mm test tubes and then were placed in 10 mls of 0.05 M Histidine, 0.15 M NaCl, pH 7.3 (Buffer).
FG clots containing saturated levels of liquid 5-FU were produced by mixing 200 μl of TFC (60 mg/ml+17 mg/ml 5-FU) with 200 μl Thrombin solution (15 U/ml+17 mg/ml 5-FU) and allowing 20 minutes for the clots to fully polymerize. The addition of saturated levels of 5-FU in both the TFC and Thrombin solutions somewhat altered clot formation producing a clot that was translucent, as compared to the control FG clots which were quite opaque. The clots that were formed were physically the same as those made with FG alone except in color. Clots were formed in 12 by 75 mm test tubes and then placed in 10 ml of buffer.
A second group of FG clots were made that contained an amount of solid anhydrous 5-FU equal to the amount included in clots formed with saturated solutions of 5-FU. These clots were formed by the addition of 7 mg of solid anhydrous 5-FU to 200 μl of TFC (60 mg/ml) and 200 μl of Thrombin (15 U/ml). Seven mg of 5-FU was placed in a 12 by 75 mm test tube. Two hundred μl of TFC was then added followed by 200 μl of Thrombin. The 3 components were then mixed by pipetting back and forth until a homogenous mixture was observed and further mixing was inhibited due to the clotting reaction. Clots were then placed in 10 ml of histidine buffer.
The final group contained 50 mg of solid anhydrous 5-FU per clot. Due to the increased mass of 5-FU (50 mg instead of 7 mg) the previously used method did not work. Instead of producing a homogenous clot, a clot was formed with the majority of the 5-FU having settled to the bottom of the test tube. To avoid this problem the bottom of the test tube was first coated with 100 μl of TFC (60 mg/ml) and 100 μl of Thrombin (15 U/ml). This formed a clot which covered the concave bottom of the test tube. Next, 50 mg of solid anhydrous 5-FU was added to the surface of the 200 μl clot. Following this, 100 μl of TFC was added along with 100 μl of Thrombin. The two solutions were mixed using an automatic pipettor until the protein started to gel. When this occurred, the pipetting was ended and the clot was allowed to polymerize for 20 minutes. The final product was a clot that contained a dense core of approximately 50 mg of 5-FU. As with the other clots, these were then placed in 10 mls of buffer. The final total protein concentration of the FG in all groups was 30 mg/ml.
Each group contained 10 replicates. Each duplicate was incubated at 37° C. in 10 mls of buffer. Buffer was exchanged for 10 mls of fresh solution at 5, 10, 22, 33, 52, 75 and 114 hours. Aliquots of the eluate buffer were then examined in a spectrophotometer at a wavelength setting of 260 nm. Previous experiments had demonstrated that 5-FU absorbed strongly at this wavelength, while eluates from control FG clots did not.
The results are shown in FIG. 32 . Control clots containing no 5-FU gave no significant readings. Clots made with 7 mg of 5-FU either in the form of saturated solutions of 5-FU or an equivalent amount of solid anhydrous 5-FU completed their delivery of 5-FU between 5 to 10 hours, while the clots containing 50 mg of solid anhydrous 5-FU continued to deliver 5-FU for at least 75 hours. Peak levels in all cases occurred at the 5 hour time point.
While not wishing to be bound by theory, it is believed that the duration of 5-FU delivery appeared to be a function of the mass of 5-FU loaded into the gel. As a result, the amount of 5-FU deliverable from the clots containing 5-FU in solution was limited by the solubility of the drug. Thus the inclusion of amounts of solid anhydrous form equal to the amount present in the clots formed from liquid saturated with 5-FU resulted in nearly identical delivery kinetics, while the inclusion of greater amounts of 5-FU in the solid form than were possible using the liquid form, resulted in a tripling of the total duration of delivery, and typically a 10-fold increase in the duration of delivery of a given concentration of the drug. It would be expected that the inclusion of still greater amounts of the solid anhydrous 5-FU would also result in even greater delivery times. In other experiments, it has been found that the amount of 5-FU included in the clots can be increased at least 5-fold and probably higher, and that the 5-FU-FG mixture can also be formulated into an injectable form (data not shown). It would further be expected that the use of an analog or other form of 5-FU that was less soluble in the surrounding aqueous medium than the anhydrous form, and/or had a slower dissolution rate, would result in a further increase in delivery times.
The result of this process is a sustainable delivery of the antiproliferative/cytotoxic drug 5-FU from fibrin clots for at least 10 times longer than is possible using the drug in the aqueous form. This technology (i.e., the use of a solid form of the drug, preferably one with a low solubility and/or dissolution rate) should be generally applicable regardless of the matrix in which the drug particles are suspended, or the drug itself.
EXAMPLE 21
Delivery of Taxol from Fibrin Sealant
Based upon the successful controlled delivery of 5-FU from a supplemented fibrin sealant matrix, protocols were developed to consider the delivery of other chemotherapeutic compounds. Recently, paclitaxel or taxol has been recognized as a very promising agent for the treatment of ovarian and breast cancers (Nicoletti et al., Ann. of Oncology 2:151 (1993)). One problem with administering taxol, systemically is that it is highly insoluble in aqueous systems. This has necessitated the use of a systemic delivery vehicle consisting of an oil and alcohol mixture (Rose, W., Anti - cancer Drugs 3:311 (1992)). Unfortunately, this systemic delivery vehicle causes severe reactions in many patients, and current therapeutic applications call for pre-medication to minimize them (Weiss, et al., J. Clin. Oncol. 8:1263(1990); Arbuck et al., Seminars in Oncol. 20:31(1993). The malignancies for which taxol is currently under clinical use are generally slow-growing, suggesting that an extended exposure to taxol from supplemented fibrin sealant would be desirable. Additionally, since the lesion produced by these diseases is often accessible clinically through percutaneous biopsy or laparoscopic procedures, the prolonged delivery of effective local concentrations of taxol from a fibrin sealant matrix appeared therapeutically feasible.
The kinetics of taxol delivery from fibrin sealant were initially evaluated, by incorporating taxol (0.26 mg), either as an anhydrous solid or dissolved in ethanol, into a 400 μl fibrin sealant composition. The resulting supplemented fibrin matrices were then placed in 2 ml histidine buffer, and incubated at 37° C. The buffer was exchanged after two days, and again ten days later. The relative concentration of taxol in the resulting eluates determined by measuring their ability to inhibit the growth of a human ovarian carcinoma cell (OVCAR) in vitro (MacPhee et al., In Current Trends in Surgical Tissue Adhesives: Proceedings of the First International Symposium on Surgical Adhesives , R. Saltz and D. Sierra, eds. Springer-Verlag).
Briefly, 1000 OVCAR cells in 100 μl of growth medium were plated into each well of a 96 well culture plate and incubated for 24 hours. A 100 μl volume of various dilutions of the eluates was then placed into the wells (10 wells per dilution), and the plates incubated at 37° C. After five days, the number of cells in each well was measured using the MTT assay (Rapaport et al., American Journal of Clinical Pathology 97:84 (1992)). In this assay, the effect of an anti-proliferative agent is seen as a decrease in the number of cells in the final cultures, and consequently, as a decrease in the amount of MTT that is converted into a chromaphore. The resulting chromaphore is detected by spectrophotometry at 570 nm. The results of the experiment and the source of each eluate is provided in FIG. 33 . (p<0.001 relative to the medium control (Dunns test)).
The controls included an initial (cellular) activity control (IAC) showing the amount of substrate produced by the OVCAR cells at the time of addition of the eluates, and the medium control, showing the maximum amount of substrate produced after 5 days in culture. The eluates from unsupplemented fibrin sealant alone did not affect this growth.
The results obtained using taxol in solution in ethanol showed that the taxol was completely delivered for up to 85 days. When taxol was incorporated into the fibrin sealant in the solid anhydrous form, the OVCAR cells were significantly inhibited for up to 85 days. Subsequent eluates recovered after an additional 10 days in culture (day 12 eluates) also significantly inhibited the growth of OVCAR cells equally well at dilutions from 1:200 to 1:20,000. This indicated that when the fibrin matrix is supplemented with the solid form of taxol, delivery was sustained beyond the initial 2 day period, and that the amount of taxol delivered in the period from day 2 to day 12 exceeded that which was delivered in the first 48 hours.
These experiments showed that long term delivery of taxol from a supplemented fibrin sealant composition can be accomplished by loading a mass of drug that exceeds its solubility in the matrix volume. This was possible both by incorporating the taxol in its solid form, as well as by dissolving it in ethanol prior to incorporation. This is because the molecular weight of ethanol is much lower than that of taxol. As a result, ethanol will rapidly diffuse from the matrix leaving the highly water insoluble taxol behind to precipitate into solid form within the matrix.
EXAMPLE 22
Fibroblast Chemotaxis in Response to Fibroblast Growth Factor-Supplemented FG and Fibronectin
Dulbecco's Modified Eagle's Medium (DMEM) was purchased from Sigma Chemical Co., St. Louis, Mo. Antibiotic-Antimycotic solution was purchased from GIBCO (Grand Island, N.Y.). Recombinant fibroblast growth factor-1 (FGF-1) and -4 (FGF-4) were a kind gift of Reginald Kidd, Plasma Derivatives Laboratory, American Red Cross, Rockville, Md., and Genetics Institute (Cambridge, Mass.), respectively. Recombinant fibroblast growth factor-2 (FGF-2, also known as basic FGF or bFGF) was purchased from Upstate Biotechnology, Inc. (Lake Placid, N.Y.) All plastic ware required for sterile propagation of cultures as well as the chemotaxis assays were purchased from Fisher Scientific (Newark, Del.). Millicell-PCF (12.0 μm) inserts were purchased from Millipore, Inc. (Bedford, Mass.). Heparin was obtained from the UpJohn Company (Kalamazoo, Mich.).
NIH/3T3 fibroblasts at passage 126 were purchased from the American Type Culture Collection, Rockville, Md. Cultures from passages 129–133 were used in the chemotaxis assays. Cultures were propagated in DMEM supplemented with 10% Calf serum and approximately 1% antibiotic antimycotic solution. Human dermal fibroblasts (HDFs) were purchased from Clonetics, Inc. (San Diego, Calif.) at passage 2. Cultures from passages 3–5 were used in the chemotaxis assays. Cultures were cultivated in DMEM supplemented with 20% FBS (Hyclone Laboratories, Inc., Logan, Utah) and approximately 1% antibiotic antimycotic solution (Gibco, Grand Island, N.Y.).
Cell Chemotaxis Assays
The procedure used to determine cellular chemotaxis was a combination of two known methodologies. A modification of Boyden's chamber was used as follows: Millicell-PCF (Millipore, Inc., Bedford, Mass.) (12.0 μm) 12.0 mm diameter inserts were placed in individual wells of 24 well plates to create the upper and lower chemotaxis chambers. Chemotaxis results were arrived at by performing checkerboard analysis for every combination of cells and growth factors. Concentrations ranging from 0.1, 1, 10, 100 ng/ml with/without added heparin (10 U/ml) were used for FGF-1, FGF-2 (no heparin) and FGF-4 with all the cell types mentioned in the materials section. Briefly, cultures were trypsinized and placed in DMEM+0.1% Bovine Serum Albumin (BSA) (Sigma Chemical Co., St. Louis, Mo.) for approximately one hour at 37° C. in a 5% CO 2 humidified chamber. Two to 2.5×10 5 cells in 50 μl were added per insert to the upper chamber of the setup of the 24 well plates. Treatments were added as mentioned above. The assay was kept at 37° C. in a 5% CO 2 humidified chamber for 4 hours. All combinations tested were performed in triplicate. At the end of 4 hours, the plates were removed from the incubator and the filters were stained following the protocol for staining included with the Millicell-PCF inserts. Briefly, the fluid surrounding the inside and outside of the Millicell-PCF inserts was removed. Three percent glutaraldehyde (Sigma Chemical Co., St. Louis, Mo.) was added to the outside and inside of the inserts for approximately 20 minutes. Following removal of the 3.0% glutaraldehyde, 0.5% Triton X-100 (E.M. Science, Cherry Hill, N.J.) was added for 5–7 minutes. On removal of the 0.5% Triton X-100, Fisher's Hematoxylin Solution Gill's Formulation (Fisher Scientific, Newark, Del.) No. 1 was added for about 10 minutes. This solution was washed off in running distilled water for about 5 minutes. Using a cotton swab the upper side of the filter was swabbed to remove cells which had not migrated. Filters were mounted lower side facing up on slides in Crystal Mount™ (Biomeda, Inc., Foster City, Calif.) solution and 10 random fields were counted per slide both visually at 400× and at 200× using an Image Analyzing System to automate the enumeration of the cells on the underside of the filters.
Checkerboard Analysis
As required, checkerboard analysis was carried out to determine random migration, and positive and negative chemotaxis. Growth factors were added to the upper and/or lower chambers to observe whether cells migrated towards the GF alone (chemotaxis), whether migration was random irrespective of whether the growth factor was added to the upper or lower well (chemokinesis) or whether cell migration was against the chemotactic gradient (negative chemotaxis).
Cell Migration Assay to FGF Released from FG
Chemotaxis chambers and cells were utilized as described above. Fifty μl of 8 mg/ml Topical Fibrinogen Complex (TFC, American Red Cross, Rockville, Md.) was added to the bottom of 24 well plates. Forty μl of test growth factor+/−heparin at a final concentration of 10 U/ml (FGF-1, FGF-4 with heparin, FGF-2 alone) was added to the TFC and thoroughly mixed. Ten μl of bovine Thrombin (Armour Pharmaceutical Company, Kankakee, Ill.) was added and mixed thoroughly. The components were allowed to gel at room temperature for approximately 30 minutes. Total volume in the lower and upper chambers was made up to 0.5 ml each with DMEM+0.1% BSA. The concentration of the FGF's added to the TFC was adjusted to produce the desired overall concentration as determined by:
Overall FGF Concentration = mg o f FGF added to TFC Volume of liquid in upper chamber +
Volume of FG & liquid in lower chamber
The assay was performed at 37° C. in a 5% CO 2 humidified chamber for approximately 24 hours. At the end of 24 hours, the filters were removed, fixed and stained and the number of cells on the underside of the filter was enumerated as described above.
Results
Capacity for Migration of Fibroblasts
The ability of NIH 3T3 fibroblasts to migrate towards various well known chemotactic agents was determined to ensure that the cells used in this assay retained this capacity. Fibronectin was the most effective chemotactic agent tested for both NIH 3T3 and HDFs with maximal responses occurring at 20 μg/ml ( FIG. 34 , Table 8). Thereafter, fibronectin at 20 μg/ml was used as the positive control for migration.
Chemotaxis of NIH 3T3 Fibroblasts Towards FGF-1
Maximum stimulation of migration of NIH 3T3 fibroblasts by FGF-1 was observed at 10 ng/ml in the presence of 10 U/ml of heparin ( FIG. 35 ). Checkerboard analysis revealed that FGF-1 was chemotactic for NIH 3T3 cells (Table 9).
Chemotaxis of NIH 3T3 Fibroblasts Towards FGF-2
Maximum stimulation of migration of NIH 3T3 fibroblasts by FGF-2 was observed at 1 ng/ml of FGF-2 ( FIG. 36 ). Checkerboard analysis showed that FGF-2 was chemotactic for NIH 3T3 cells (data not shown).
Chemotaxis of NIH 3T3 Fibroblasts Towards FGF-4
Maximum stimulation of migration of NIH 3T3 fibroblasts by FGF-4 was observed at 10 ng/ml ( FIG. 37 ). Checkerboard analysis revealed that FGF-4 was chemotactic for NIH 3T3 cells (data not shown).
Chemotaxis of HDFs Towards FGF-1
Maximum stimulation of migration of HDFs by FGF-1 was observed from 1 to 10 ng/ml ( FIG. 38 ). Checkerboard analysis showed that FGF-1 was chemotactic for HDFs (Table 10).
Chemotaxis of HDFs Towards FGF-2
Maximum stimulation of migration of HDFs by FGF-2 was observed at 10 ng/ml ( FIG. 39 ). Checkerboard analysis revealed that FGF-2 was chemotactic for HDFs (data not shown).
Chemotaxis of HDFs Towards FGF-4
Maximum stimulation of migration of HDFs by FGF-4 was observed at 10 ng/ml ( FIG. 40 ). Checkerboard analysis showed that FGF-4 was chemotactic for HDFs (data not shown).
Human Dermal Fibroblast Migration to FGF-1, -2 and -4 Incorporated in FG
Maximal migratory response to FGF released from FG was elicited at an incorporated and total concentration of FGF-4 in FG of 1 ng/ml ( FIG. 41 ). Similar results were also found when FGF-1 and FGF-2 were incorporated into the FG (data not shown) except that the concentration of FGF-2 that elicited the peak chemotactic response was 0.01 mg/ml.
TABLE 8
Concentration
of Fibronectin
In Lower
Concentration of Fibronectin In Upper Compartment
Compartment
0 μg/ml
10 μg/ml
20 μg/ml
50 μg/ml
0 μg/ml
48.53 +/−
62.3 +/−
69.6 +/−
62.0 +/−
4.695
3.269
12.25
2.616
10 μg/ml
68.03 +/−
47.53 +/−
64.86 +/−
74.66 +/−
10.793
5.605
7.961
3.946
20 μg/ml
90.53 +/−
88.73 +/−
56.9 +/−
76.23 +/−
5.203
4.152
3.289
1.8190
50 μg/ml
72.43 +/−
91.3 +/−
63.26 +/−
57.46 +/−
8.276
1.003
3.835
2.287
TABLE 9
Concentration
of FGF-1 In
Lower
Concentration of FGF-1 In Upper Compartment
Compartment
0 ng/ml
1 ng/ml
5 ng/ml
10 ng/ml
0 ng/ml
32.1 +/−
53.93 +/−
27.27 +/−
25.96 +/−
6.328
4.152
3.873
4.151
1 ng/ml
59.46 +/−
36.9 +/−
22.1 +/−
35.86 +/−
6.89
5.728
9.232
2.074
5 ng/ml
64.867 +/−
41.44 +/−
24.84 +/−
41.6 +/−
1.75
1.866
4.337
6.717
10 ng/ml
70.83 +/−
39.73 +/−
39.73 +/−
41.83 +/−
2.752
2.428
2.428
6.879
TABLE 10
Concentration of
FGF-1 in Lower
Concentration of FGF-1 In Upper Compartment
Compartment
0 ng/ml
0.1 ng/ml
1 ng/ml
10 ng/ml
100 ng/ml
0 ng/ml
1.96 +/−
48. +/−
1.3 +/−
4.6 +/−
2.4 +/−
.602
1.965
0.351
2.424
2.59
0.1 ng/ml
66.46 +/−
3.5 +/−
22.0 +/−
9.7 +/−
11.6 +/−
3.304
1.550
6.621
7.758
8.609
1 ng/ml
90.0 +/−
27.7 +/−
52.6 +/−
9.7 +/−
1.83 +/−
5.776
8.10
2.775
3.553
2.2
10 ng/ml
92.4 +/−
55.1 +/−
44.2 +/−
16.2 +/−
21.2 +/−
29.307
7.151
11.844
4.781
6.42
100 ng/ml
65.4 +/−
53.7 +/−
54.9 +/−
49.166 +/−
4.66 +/−
22.055
7.3118
18.599
9.152
3.3
Discussion
The FGFs produced a profound chemotactic response in HDFs. For every chemotactic assay performed with HDFs, a very good distinction was obtained between the negative control and the concentration of FGF which elicited a maximal migratory response: 18, 12 and 10 fold in response to FGF-1, -2 and -4, respectively.
The stimulation of chemotaxis by growth factors was not as high for NIH 3T3 cells as it was for HDFs, possibly due to the high passage number of the available stock cultures of the NIH 3T3 cells as compared to the HDFs.
FGF-1, FGF-2 and FGF-4 were found to be potent stimulators of fibroblast chemotaxis. Directed migration of fibroblasts by one or a combination of the above growth factors could result in fibroblast presence in the site of injury, thereby leading to fibroplasia and the laying down of collagen and an extracellular matrix. Thus, aside from it's well recognized angiogenic properties, FGF's may have a role in wound healing, acting either alone or in a combination with PDGF, IGF-I, TGF-β and/or other factors.
Previous studies into the use of FGF's to speed wound healing have not yielded significant results (Carter et al., 1988). This may be due to a requirement for the prolonged exposure of cells to the factors in vivo for a maximal response (Presta et al., Cell Regul. 2:719–726 (1991) and Rusnati et al., J. Cell. Physiol. 154:152–161 (1993)). Unfortunately, it is difficult to deliver growth factors to wounds for such long time periods under conditions that would not interfere with the healing process.
The present invention of incorporating FGFs into FG allows for the prolonged exposure of cells to the FGFs and can be applied to a wound. The resulting fibrin coating mimics the natural response to tissue injury, while delivering the growth factor directly to the wound site. In a previous study by the present inventors, FG which contained FGF-1 was used to line artificial vascular grafts (Example 8, herein). When these grafts were placed into the vessels of rabbits, the FGF-1 was released for a period of up to 28 days. In further studies involving canine grafts, the effect of the incorporation of FGF-1 into the graft walls was the total endothelialization of the artificial grafts within the same period (Greisler et al., Surgery 112:244–255 (1992)). Thus, this form of application elicits a profound biological effect in vivo. The fibroblasts are attracted towards FGF released from FG. This property will be useful in treating wounds with GF-supplemented TS.
EXAMPLE 23
Site-Directed Angiogenesis Using TS to Deliver Angiogenic Substances
This embodiment permits the directed generation of new blood vessels in a controlled manner within the body. In this embodiment, the TS contains and delivers angiogenic substances, such as Fibroblast Growth Factor-1 (FGF-1), in an amount such that its concentration which is released from the supplemented TS is effective to induce angiogenesis.
This embodiment is used in a controlled manner to revascularize body areas which have been deprived of an adequate blood supply such as cardiac, brain and muscle tissue, and the retina. This embodiment is used to restore or improve circulation to implanted organs or re-attached limbs. This embodiment can be used to generate a vascular network or “vascular bed” for: the generation of artificial organs or organoids, the delivery and/or localization of and/or nourishment of cells used in gene therapy, or as a target of gene therapy, for the nourishment and/or localization of cells for tissue augmentation. This embodiment also precludes the necessity of implantation of a device or substance which may induce a foreign body or other excessive inflammatory reaction which could compromise the blood vessel formation or the function of the underlying organ(s).
The invention consists of a formulation of fibrinogen, (suitable for the formation of fibrin) with or without fibronectin and/or collagen, into which is placed an appropriate concentration of an angiogenic substance, such as FGF-1. The fibrinogen may also contain stabilizers to protect against the proteolytic activity of Thrombin. In the case of FGF-1, heparin sulfate (1–1000 U/ml) may be used as the stabilizer in the range of concentration of from 1 ng/ml to 1 mg/ml. Alternatively the angiogenic substance is contained, in an appropriate concentration, in the thrombin, calcium, or water components. This formation is then mixed with thrombin and rapidly applied within the body in a line connecting the desired sites, or to a single site. The fibrinogen-thrombin mix then polymerizes to form FG. The FGF-1, or other angiogenic substance, remains trapped in the FG matrix, either as a free form or bound to the stabilizer or another component of the mixture. In one embodiment, the concentration of the FGF-1 in the TS should be from 0.1 ng/ml to 1 mg/ml, more preferably from 1 ng/ml to 100 μg/ml, most preferably from 100 ng/ml to 10 μg/ml. The FGF-1, or other angiogenic substance, will induce blood vessel formation within the body of the deposited FG. The FG will be naturally biodegraded leaving the intact blood vessel(s).
EXAMPLE 24
Site-Directed Cartilage Induction
This embodiment permits the controlled generation of new cartilage as well as the guided regeneration of damaged cartilage within the body. In this embodiment the TS contains and delivers a cartilage promoting factor(s), such as cartilage-inducing factors-A and/or -B (CIF-A and CIF-B, respectively, which are also known as TGF-B 1 and TGF-B 2 , respectively) and/or another, factor(s) such as Osteoid-Inducing Factor (OIF) in an amount such that the concentration of the inducing factor(s) which is released from the supplemented TS is effective to induce cartilage formation. In one embodiment the concentration of the inducing factors should be 0.1 ng/ml to 1 mg/ml, more preferably from 1 ng/ml to 500 ng/ml, most preferably from 100 to 250 ng/ml. This embodiment may also contain drugs, such as antibiotics, and other growth factors, such as EGF, PDGF, and bFGF in the TS. The cartilage inducing substance is contained in an appropriate concentration in the fibrinogen or thrombin or calcium or water component(s) which are used to prepare the TS.
The supplemented TS can either be pre-shaped to the desired final cartilage form prior to implantation or it can be implanted into the body of the recipient in the liquid form as the TS is mixed and polymerizes. The resulting form may then be sculpted as desired to produce the required shape of cartilage needed. The Cartilage Inducing TS (CI-TS) mixture can also be used to precoat a conventional implant, with the result being a conventional implant with a coating of living cartilage.
Using any of the techniques described above, the CI-TS is then implanted into the body of the recipient. This implantation can be heterotopic or orthotopic. After an appropriate interval, the CI-TS is be replaced by living cartilage with the form of the original CI-TS implant.
Such implants can be used to replace damaged or lost cartilage, or to improve the tissue integration and/or function of an artificial implant. Examples of such uses include the replacement or reconstruction of nasal or ear tissue, the generation of a functional joint surface on a bone implant grown in vivo, or the generation of a similar surface on an artificial implant. The repair of cartilage damaged by disease, such as rheumatoid arthritis, can also be accomplished using the CI-TS to produce a new and smooth cartilage surface to the arthus. Implants intended for space filling applications in Plastic/Reconstructive surgery can also be either formed from CI-TS, or coated with CI-TS to enhance tissue integration and reduce foreign body reactions.
Since current technology does not permit the guided regeneration of cartilage, this invention is an advancement because it permits the generation of cartilaginous tissue which is required to fully mimic the body's natural make-up. This results in improved joint repair, artificial joints and other implants, both for orthopedic and other applications.
For example, this embodiment can be used: to produce improved orthopedic implants or improved plastic/reconstructive implants: for joint repair for traumatic, congenital or pathologically damaged or dysfunctional cartilage; to produce coatings of pacemaker implants and wires to increase their tissue integration and to reduce foreign body reactions. Similar coatings could also be applied to any implantable device for the similar purposes.
EXAMPLE 25
Supplemented TS as a Surface Coating for Biomaterials
This embodiment uses supplemented TS as a coating for the surfaces of orthopedic devices and other biomaterials which are to be implanted into an animal's body. Examples of these devices are urinary catheters, intravascular catheters, sutures, vascular prostheses, intraocular lenses, contact lenses, heart valves, shoulder/elbow/hip/knee replacement devices, total artificial hearts, etc. Unfortunately, these biomaterials may become sites for bacterial adhesion and colonization, which eventually may lead to clinical infection that will endanger the life of the animal. To minimize this problem, the biomaterial is coated with a supplemented TS.
In this embodiment the TS can be supplemented with: a growth factor(s); a drug(s), such as an antibiotic; BMP; and/or cultured cells, etc. Examples of antibiotics that may be incorporated into the TS include, but are not limited to: the penicillins; cephalosporins; tetracyclines; chloramphenicols; metronidazoles; and aminoglycosides. Examples of growth factors which may be incorporated into the TS include but are not limited to FGF, PDGF, TGF-β. Examples of BMPs which may be incorporated into the TS include, but are not limited to, BMP 1 through 8. DBM can also be added to the TS. Examples of cultured cells which may be incorporated into the TS include, but are not limited to, endothelial cells, osteoblasts, fibroblasts, etc.
The supplement(s) may be contained in either the thrombin, fibrinogen, calcium or water component(s). The concentration of the supplement in the TS is adequate such that it will be effective for its intended purpose, e.g., an antibiotic will inhibit the growth of microbes on the biomaterial, a growth factor will induce the growth of the desired cell type(s) in the TS and/or on the surface of the biomaterial.
This invention is an improvement for existing biomaterial products, which include titanium and titanium alloy devices (such as fixation plates, shoulder/elbow/hip/knee replacement devices, osseointegrated dental implants, etc), solid silicone products (such as Silastic nasal implants, liquid and/or gel silicone products (such as breast implants and testicular implants), and natural or synthetic polymers used as conventional materials in healing a wound site, which may have various forms, such as monofilaments, fibrous assemblies (such as cotton, paper, nonwoven fabrics), films, sponges, bags, etc.
FG is produced from 3 components: fibrinogen (for example as TFC); and thrombin, both of which may be in the lyophilized form; as well as calcium. The lyophilized fibrinogen is reconstituted with sterile water, while the thrombin component is reconstituted with calcium chloride solution. A supplement may be added to any of the three components prior to mixing. Appropriate volumes of the fibrinogen and thrombin containing calcium are mixed to produce the FG. The FG is then applied to the biomaterial's surface as a coating thereof as, for example, by spraying, painting, etc. Alternatively, the implant is dipped in the FG while it is still liquid. A supplement may also be added to the FG before or after it has been coated on a biomaterial surface. For instance, a FG-coated implant is soaked in an antibiotic solution for a specified period of time so that the antibiotic will diffuse into the TS. Another example is coating a device with TS after which cultured cells are seeded onto the fibrin coating. Coating the surface of biomaterials, which will be implanted into an animal, with supplemented TS will serve several purposes, including: the inhibition of bacterial adhesion to the biomaterial; the inhibition of growth of bacteria adhered to the biomaterial; local immune stimulation and/or normalization; the promotion of would healing; and the promotion of engraftment of the biomaterial to the surrounding tissue.
EXAMPLE 26
Self-Contained, TS Wound Dressing
This embodiment is a self-contained TS wound dressing, or bandage, which contains both the thrombin and fibrinogen components of the FG. The calcium is contained in either the thrombin and/or the fibrinogen component(s). Either or both of the thrombin or fibrinogen components can be, but does not have to be, supplemented with a growth factor(s), such as a FGF or bFGF, or a drug(s) such as, an analgesic, antibiotic or other drug(s), which can inhibit infection, promote wound healing and/or inhibit scar formation. The supplement(s) is at a concentration in the TS such that it will be effective for its intended purpose, e.g., an antibiotic will inhibit the growth of microbes, an analgesic will relieve pain.
The thrombin and fibrinogen are separated from each other by an impermeable membrane, and the pair are covered with another such membrane. The thrombin and fibrinogen are contained in a quick evaporating gel (e.g., methylcellulose/alcohol/water). The bandage may be coated on the surface that is in contact with the gel in order to insure that the gel pad remains in place during use. (See FIG. 42 ).
In operation, the membrane separating the two components is removed, allowing the two components to mix. The outer membrane is then removed and the bandage is applied to the wound site. The action of the thrombin and other components of the fibrinogen preparation cause the conversion of the fibrinogen to fibrin, just as they do with any application of FS. This results in a natural inhibition of blood and fluid loss from the wound, and the establishment of a natural barrier to infection.
In a similar embodiment, the thrombin component and the plastic film separating the Thrombin gel and the Fibrinogen gel may be omitted. The calcium that was previously in the Thrombin gel may or may not be included in the Fibrinogen gel as desired. In operation, the outer impervious plastic film is removed and the bandage applied, as previously described, directly to the wound site. The Thrombin and calcium naturally present at the wound site then induce the conversion of fibrinogen to fibrin and inhibit blood and fluid loss from the wound as above. This embodiment has the advantage of being simpler, cheaper, and easier to produce. However, there may be circumstances in which a patient's wounds have insufficient thrombin. In those cases, the previous embodiment of the invention should be used.
This embodiment is an advancement over the current technology as it permits the rapid application of TS to a wound without the time delay associated with solubilization and mixing of the components. It also requires no technical knowledge or skill to operate. These characteristics make it ideal for use in field applications, such as in trauma packs for soldiers, rescue workers, ambulance/paramedic teams, firemen, in first aid kits for the general public, and by emergency room personnel in hospitals. A small version may also be useful for use by the general public.
EXAMPLE 27
Additional Self-Contained, TS Wound Dressings
The TSs may be formulated as a self-contained wound dressing, or fibrin sealant bandage, which contains the necessary thrombin and fibrinogen components of the FG. The self-contained dressing or bandage is easy-to-use, requiring no advanced technical knowledge or skill to operate.
The Fibrin Sealant Bandage
The present inventors have prepared a fibrin sealant bandage for applying a tissue sealing composition to wounded tissue in a patient, wherein the bandage comprises, in order: (1) an occlusive backing; (2) a pharmacologically-acceptable adhesive layer on the wound-facing surface of the backing; and (3) a layer of dry materials comprising an effective amount, in combination, of (a) dry, virally-inactivated, purified tissue fibrinogen complex, (b) dry, virally-inactivated, purified thrombin, affixed to the wound-facing surface of the adhesive layer or backing, and (c) calcium chloride. A removable, waterproof, soft plastic, protective film was placed over the layer of dry materials and the exposed adhesive surface of the bandage for stable storage purposes. In operation the waterproof, protective film is removed prior to the application of the bandage over the wounded tissue. The bandage was applied with pressure until the TS has formed over the target area.
The fibrin sealant bandage was tested using a conventional, adhesive silicone patch measuring 6 cm×5 cm, having a total area of 30 cm 2 . The dry components were placed over the adhesive patch to a depth of ½ cm, so that the total volume of fibrin formed by the TS upon hydration equaled 15 cc (30 cm 2 ×½ cm). The materials used were: 360 mg of topical fibrinogen complex (TFC), described previously; approximately 340 U thrombin, also described previously; and 88 mg CaCl 2 (40 mM).
The binding capacity of the bandage for the dry material layer was, in part, dependent upon applying the dry materials as a uniformly-ground, fine powder. The calcium chloride was ground to a fine powder and mixed with the finely ground lyophilized TFC and thrombin, and applied as a powder to the adhesive side of the silicone patch and allowed to adhere to form the fibrin sealant patch. In additional versions of the fibrin sealant bandage, the dry materials were mixed and ground together.
Significantly more of the finely ground powder adhered to the silicone patch when pressure was applied. However, the quantity of dry material added to the fibrin sealant bandage was quantifiable. It was found, for example, in one application using the silicone patch backing that an area, 2×1 cm 2 , when completely covered by the dry fibrin components increased in weight by 30 mg. This measurement was extrapolated to a dry fibrin component mass per area covered on the backing of 15 mg/cm 2 .
The fibrin sealant patch was applied to a damp cellulose sponge, representative of a tissue wound, so that the fibrin sealant component was adjacent to the surface of the sponge. The sponge had been previously dampened with room-temperature distilled H 2 O.
Fibrin formation began to develop within 30 seconds of application. Within three minutes of application, a fibrin gel had formed affixing the tissue sealing fibrin clot to the sponge. This first patch hydrated by the endogenously available liquid was labeled FSB#1.
The previous steps were repeated to prepare patches FSB#2 through FSB#5, however, prior to placing the fibrin sealant bandage against the dampened cellulose sponge, 8 ml of warm PBS were applied to the dry fibrin components affixed to the patch. Incubation of applied patches FSB#2 through FSB#5 was at 37° C. rather than
TABLE 11
Time
Bandage
3′
5′
10′
15′
20′
30′
120′
180′
2
clotted
clotted
clotted
clotted
clotted
clotted
clotted
clotted
3
in sol’n
in sol’n
in sol’n
in sol’n
in sol’n
in sol’n
in sol’n
in sol’n
4
in sol’n
in sol’n
in sol’n
in sol’n
in sol’n
in sol’n
in sol’n
in sol’n
5
in sol’n
very weak gel
weak gel
weak, watery gel
TABLE 12 Volume Carbonated Initial Volume Final Volume Experiment # TFC Thrombin CaCl 2 H 2 O Fibrin Mass Fibrin Mass 1 51.4 mg/ml 57 U/ml 7.1 mM 3 mls. 7 mls. 35 mls. 2 30 mg/ml 29 U/ml 7.1 mM 8 mls. 12 mls. 3 60 mg/ml 66.7 U/ml 8.3 mM 5 mls. 12 mls. 4 60 mg/ml 58 U/ml 7.1 mM 10 mls. 24 mls. 120 mls.
room temperature. The results, set forth in Table 11, exemplify the an application of the fibrin sealant bandage embodiment wherein the dry materials are exogenously hydrated prior to application.
Patch FSB#3 was prepared the same as FSB#1, but absent the thrombin component. Patch FSB#4 was prepared the same as FSB#1, but absent the TFC component. Patch FSB#5 was prepared the same as FSB#1, but absent the calcium chloride component. The results of each test were evaluated over time. As shown below in Table 11, a clotted gel formed when the fibrin components were hydrated with PBS, but remained in solution when either the fibrinogen or thrombin components were deleted from fibrin sealant bandage composition. Similarly, although a weak, watery gel was formed after 30 minutes when the calcium component was deleted from the fibrin sealant bandage and from the hydrating fluid, the composition was unable to develop into a tissue sealing fibrin clot.
To more clearly visualize the formation of the fibrin clot and the extend to which it bound to adjacent surfaces, a small amount toluidine blue was ground into the powdered fibrin components as a color indicator.
In practice, with sufficient hydration the silicone patch was easily removed from the fibrin clot after hydration of the dry, fibrin component layer.
The fibrin sealant bandage, formulated on silicone patches as described above, were also found to effectively form fibrin seals when tested on gelatin surfaces and in vivo on rat tissue. Based on the successful formation of the fibrin seal to a variety of materials and textures, including basic in vivo testing on an uninjured rat, animal studies will be conducted as described in the previous Examples evaluating the TS composition to optimize the hemostatic utility of the fibrin sealant bandage, and to establish delivery kinetics of supplementary components to be added, e.g., growth hormones, drugs, antibiotics, antiseptics, etc.
The Self-Foaming Fibrin Sealant
The present inventors have prepared a self-foaming fibrin sealant dressing for applying a tissue sealing composition to wounded tissue in a patient, wherein the dressing is applied as an expandable foam comprising an effective amount, in combination, of (1) virally-inactivated, purified fibrinogen complex, (2) virally-inactivated, purified thrombin, (3) calcium, and (4) a physiologically acceptable hydration agent; wherein said composition does not significantly inhibit full-thickness skin wound healing. In practice, the previously described TS components will be stored in a canister or tank with a pressurized propellant, so that the components are delivered to the wound site as an expandable foam, which will within minute(s) form a fibrin seal.
A bench model test system is prepared from standard Amicon pressure chambers to determine optimal particle size. Particle size has proven to be important. Preliminary experiments have revealed that a reduction in particle size of the TFC, fibrin and calcium components results in a significant reduction in the time required to hydrate the reagents.
Testing is also relevant to determining the feasibility of combining all of the reagents within a single reservoir, or whether it is more advantageous to maintain each component in a separate reservoir until application. Although probably more expensive, the latter canister prototype (having multiple separate reservoirs) may prove advantageous, in terms of stability and long-term storage.
The test system consists of one or two pressure vessels driven by a pressurized reservoir containing the pharmaceutically acceptable hydrating agent (e.g., water or PBS), and pressurized compressed gas cylinders. The reagents are placed into the appropriate chamber(s) and the reservoir charged with hydrating agent saturated with the propellant at the desired pressure. Mixing of water and the reagents in their reservoirs is accomplished by opening connecting valves. The output is directed into either a single line, or in the case in which the components remain separated, into the joining piece of a Hemedics Fibrin Sealant Dispenser.
In the present case, the TFC was rehydrated with 3 cc dH 2 O, and warmed to 37° C. to the concentrations shown in Table 12. The thrombin was rehydrated with 0.5 cc CaCl 2 solution (100 mM) to the concentrations shown in Table 12. The hydrated components were mixed and carbonated water (10 cc) was added to produce the volumes shown in Table 12. The resulting foaming mixture was placed in a vacuum jar to increase the foaming. Vacuum pressure was applied until the foam dried. The result was a permanent, integrated, foamy mass of fibrin, which expanded approximately 5-fold, and which was both self-adherent and adherent to adjacent textured surfaces.
The foam was also quantitatively measured in calibrated plastic beakers. After two minutes, the volume of the foam was measured and the mass was gently probed to determine that it had set. The quantitative measurements of the expansion of the self-foaming fibrin sealant is indicated in Table 12. Once set, the expandable foam was no longer adhesive to new surfaces.
Based on the successful formation of the self-foaming fibrin dressing, animal studies will be conducted as described in the previous Examples evaluating the TS composition to optimize the hemostatic utility of the self-foam fibrin sealant dressing, and to establish delivery kinetics of supplementary components to be added, e.g., growth hormones, drugs, antibiotics, etc.
Other embodiments of the invention will be apparent to those of skill in the art from a consideration of this specification or practice of the invention disclosed herein. Since modifications will be apparent to those of skill in the art, it is intended that this invention be limited only by the scope of the appended claims.
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This invention provides a fibrin sealant bandage, wherein said fibrin sealant may be supplemented with at least one composition selected from, for example, one or more regulatory compounds, antibody, antimicrobial compositions, analgesics, anticoagulants, antiproliferatives, anti-inflammatory compounds, cytokines, cytotoxins, drugs, growth factors, interferons, hormones, lipids, demineralized bone or bone morphogenetic proteins, cartilage inducing factors, oligonucleotides polymers, polysaccharides, polypeptides, protease inhibitors, vasoconstrictors or vasodilators, vitamins, minerals, stabilizers and the like. Also disclosed are methods of preparing and/or using the unsupplemented or supplemented fibrin sealant bandage.
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CROSS REFERENCE TO A RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser. No. 08/711,499, which was filed Sep. 10, 1996 and claims priority from U.S. Provisional Application Serial No. 60/023,536, filed Aug. 7, 1996 and entitled “LASER SCRIBING THROUGH A METAL FILM FOR REDUCED CONTAMINATION AND ENHANCED CONTRAST”.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to disc drive data storage systems and, more particularly, to a method of applying a serial number or other information pattern to a surface of a disc head slider.
[0003] Disc drives of the “Winchester type” are well known in the industry. Such drives use rigid discs coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor which causes the discs to spin and the surfaces of the discs to pass under respective head gimbal assemblies (HGAs). The HGAs carry transducers which write information to and read information from the disc surface. An actuator mechanism moves the HGAs from track to track across the surface of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a load beam for each HGA. The load beam provides a preload force which presses the HGA toward the disc surface.
[0004] The HGA includes a hydrodynamic (e.g. air) bearing slider and a gimbal. The gimbal is positioned between the slider and the load beam to provide a resilient connection that allows the slider to pitch and roll while following the topography of the disc. The slider includes a slider body having a leading edge, a trailing edge and an air bearing surface which faces the disc surface. As the disc rotates, the disc drags air under the slider along the air bearing surface, which creates a hydrodynamic lifting force that causes the slider to lift and fly above the disc surface. The transducer is typically mounted at or near the trailing edge of the slider.
[0005] Air bearing disc head sliders are formed from a substrate known as a wafer. A matrix of transducers is applied to a top surface of the wafer and then the wafer is sliced into a plurality of bars. Each bar includes a plurality of individual slider bodies, with each body having a corresponding transducer. Each bar is then diced into individual slider bodies.
[0006] It is often desired to apply a serial number or some other useful information to each slider body. Serial numbers have been applied to the leading edges of slider bodies by a laser scribing process. During the laser scribing process, a beam of laser light is directed toward the slider substrate material. The beam removes material in a pattern corresponding to the serial number. A disadvantage of the laser scribing process is that the removed material often redeposits on the slider substrate, which creates contamination. Furthermore, the legibility of the applied serial number is occasionally questionable.
SUMMARY OF THE INVENTION
[0007] One embodiment of the present invention is directed to a disc head slider for use in a disc drive data storage system. The disc head slider includes a slider body having a slider substrate material with a surface. A transducer is supported by the slider body, and a film is applied to the surface and graphically represents a character pattern.
[0008] Another embodiment of the present invention is directed to a disc head slider, which includes a slider body having a slider substrate material with a surface, a transducer supported by the slider body, and a metal film applied to the surface. An information pattern is defined by the metal film and graphically represents a serial number for the disc head slider.
[0009] Yet another embodiment of the present invention is directed to a disc head slider substrate wafer. The wafer includes an upper surface and a lower surface, which is opposite to the upper surface. A plurality of individual slider body locations are defined within the wafer. A plurality of transducers are fabricated on the upper surface, wherein each transducer is positioned at a corresponding one of the individual slider body locations. A film is applied to the lower surface. A plurality of graphical patterns are defined by the film, wherein each graphical pattern is positioned at a corresponding one of the individual slider body locations and represents a serial number for that slider body location.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] [0010]FIG. 1 is a perspective view of a wafer of slider substrate material from which a slider according the present invention is fabricated.
[0011] [0011]FIG. 2 is a fragmentary perspective view of a bar of slider bodies sliced from the wafer shown in FIG. 1.
[0012] [0012]FIGS. 3 a - 3 c are end views of a slider body during a slider fabrication process according to the present invention.
[0013] [0013]FIG. 4 is a greatly magnified illustration of a letter which was laser scribed on a metal film according to the present invention.
[0014] [0014]FIG. 5 is a greatly magnified illustration of a letter laser scribed on an uncoated slider substrate according to the prior art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Hydrodynamic bearing disc head sliders are formed from a substrate known as a wafer. FIG. 1 is a perspective view of typical wafer 10 . Wafer 10 can include aluminum oxide titanium carbide, aluminum silicon magnesium or silicon, for example. Wafer 10 has a top surface 11 and a bottom surface 12 . In a typical fabrication process, a matrix of transducers (not shown) is applied to top surface 11 . Wafer 10 is then sliced along rows 13 into a plurality of bars 14 . Each bar 14 includes a plurality of individual slider bodies, with each body having a corresponding transducer. FIG. 2 is fragmentary, perspective view of a bar of slider bodies sliced from wafer 10 . Each bar 14 includes a plurality of individual slider bodies 16 , with each slider body having a corresponding transducer 18 . The sliced surfaces become bearing surface 20 and back surface 22 . The top surface 11 of wafer 10 becomes trailing surface 24 and the bottom surface 12 of wafer 10 becomes leading surface 26 .
[0016] Once wafer 10 has been sliced into individual bars 14 , air bearing features are formed into the bearing surface 20 of each slider body 16 . Once the air bearing features have been formed, each bar 14 is diced along a plurality of dice lanes 28 into the plurality individual slider bodies 16 .
[0017] In order to identify each slider body 16 , a serial number is formed on the leading surface 26 of each slider body 16 . The serial number can be applied at the wafer level shown in FIG. 1, the bar level shown in FIG. 2 or the slider level. In a preferred embodiment, the serial number for each slider body is applied at the wafer level by laser scribing the serial number to the bottom surface 12 of wafer 10 at an appropriate location. However, for simplicity, the process of applying the serial number to the slider substrate material will be discussed with reference to an individual slider body.
[0018] [0018]FIGS. 3 a - 3 c are perspective views illustrating an individual slider body during various steps of the fabrication process of the present invention. FIG. 3 a illustrates slider body 16 after dicing. Slider body 16 includes air bearing surface 20 , back surface 22 , trailing surface 24 and leading surface 26 . The air bearing features have been formed in air bearing surface 20 and include raised side rails 30 and 32 .
[0019] In FIG. 3 b , a thin, metal film 34 is applied to leading surface 26 . Metal film 34 can be applied by sputtering, plating, chemical vapor deposition or other means for applying a thin metal coating. Metal film 34 has a thickness 36 which can range from a monolayer to several microns, such as 5.0 microns. In a preferred embodiment, thickness 36 is 100-1000 angstroms. Metal film 34 can be applied to the entire leading surface 26 or only a portion of leading surface 26 . Metal film 34 preferably has good adhesion properties. Suitable materials for metal film 34 include chrome, tantalum, and molybdenum, for example. However, any suitable metal material can be used for metal film 34 .
[0020] In FIG. 3 c , a serial number 38 is formed in metal film 34 by laser “scribing” or laser “etching”. A beam of laser light 40 is directed from light source 42 toward metal film 34 . The beam of laser light 40 applies radiation to metal film 34 in the form of a high peak, short duration photon energy pulse which is raster scanned over metal film 34 in a pattern 38 corresponding to the desired serial number or other useful information. The radiation ablates the metal film material within pattern 38 .
[0021] In a preferred embodiment, the laser spot energy density and the pulse duration are adjusted such that the metal film material is completely removed within pattern 38 without removing any underlying slider substrate material. Laser scribing can be preformed by using a pulsed YAG laser, such as a 532 nm double YAG laser or a UV laser. CO 2 lasers and excimer lasers are other examples of lasers that can be used. Also, a continuous wave laser beam can be used instead of a pulsed beam. These lasers have different wavelength energies and different beam characteristics which may be advantageous in specific applications and on specific materials.
[0022] Laser scribing the serial number into metal film 34 , as opposed to directly into the slider substrate material, results in greater contrast in the scribed pattern, which makes the serial number more legible. Also, metal film 34 can be formed very thin, which results in less material being redeposited on the slider substrate and thus less contamination. The decrease in redeposited material also results in less material accumulation at the edge of pattern 38 . This further increases legibility.
[0023] In another embodiment, the laser spot energy density and the pulse duration are adjusted such that material is removed to a depth which is less than the thickness of metal film 34 . In yet another embodiment, material is removed to a depth which is greater than the depth of metal film 34 . In this embodiment, a portion of the slider substrate material which underlies metal film 34 is also removed. The desired pattern is formed through metal film 34 and into the slider substrate material. Metal film 34 can then be stripped from the slider substrate, leaving the desired pattern in the slider substrate. Alternatively, metal film 34 can be left on the slider substrate.
[0024] [0024]FIG. 4 is a greatly magnified illustration of a letter X laser scribed within metal film 34 , as described with reference to FIG. 3 c . The letter X is clearly legible on metal film 34 .
[0025] [0025]FIG. 5 is a greatly magnified illustration of a letter X laser scribed within an uncoated slider substrate according to the prior art. The letter X is much less legible than in FIG. 4. In addition, with an uncoated slider, the laser scribing often creates contamination through substrate redeposition.
[0026] Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For example, the position of the serial number is not limited to the leading surface of the slider substrate. The serial number can be applied to any surface on the slider substrate in accordance with the present invention. Also, other useful information can be laser scribed into the slider substrate, such as a date of manufacture or a company logo.
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A disc head slider is provided for use in a disc drive data storage system. The disc head slider includes a slider body having a slider substrate material with a surface. A transducer is supported by the slider body, and a film is applied to the surface and graphically represents a character pattern.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a key board adapted for use in appliances such as computers or related terminals, etc., and more particularly, to a multipurpose optical intelligent key board apparatus affording the user a variety of key inputs.
2. Description of the Related Art
A general key board is called an "input device" and when adapted to an electronic appliance, it is arranged to have a predetermined number of keys, each associated with a corresponding function. In other words, a key board used in an appliance such as a computer or related terminal is commonly supplied with keys bearing English characters. In many foreign countries, each English character on a specific key is accompanied by a corresponding character in the mother country tongue, whereby the two different characters are printed or moulded in a predetermined arrangement to be harmonized with the corresponding literary syntax system. Furthermore, because the literary syntax systems in each of the European Alphabetic countries have a greater range of characters and vowel possibilities than the English language, the key boards in each corresponding country force the positions of the keys produced in a new key board pattern. Typical characters used include those used in the German, French, Spanish languages.
During the 1980s, various computer software programs became standardized by using personal computers compatible with IBM-PCs which utilize "MS-DOS" software. To keep up with these developments, a computer key board is provided with ten or twelve keys having different purposes of use, called "function keys", which serve functions according to the software to be used. These "function keys", along with "ALT, CTRL, SHIFT and other Keys" are supported by various command words associated with their combination according to the software programming. However, it is inevitable to issue different command words corresponding to the programming of each software program because of the characteristics of the software. Nevertheless, standardization for the use of these keys has been impossible till now. Therefore, computer users are required to study the operating manual and ask the computer for help by pressing the function key F1 or a HELP key. Also, it takes a long time to become familiar with the corresponding program, and the use of new software requires learning its procedures. Most programming corresponding to the software to be used is utilized only on the basis of several command words being well known to the user, and the efficiency of use of the software is thereby reduced.
One part of most applied software programs divides a particular portion of a terminal screen, or it supports the user facility based on the window concept. However, these functions occupy part of the memory area independent of the predetermined memory region for starting the main program to be used. Therefore, it limits the operating capacity of a computer and thereby deteriorates the operating efficiency.
Software such as "AUTOCAD" is configured to use two screens, one of which becomes exclusively a command word space and the other of which forms the working space. This multi-screen system causes inconvenience, it is non-economic, and it is inefficient for the user. Touch screens or Liquid Crystal Touch screens have been developed as alternatives for resolving these problems, but these methods have disadvantages in respect of the user's degree of acquaintance with them and errors in operation caused by careless mistakes.
Considering these points, the main object of the present invention is to provide a multipurpose optical intelligent key board apparatus for performing the optical supporting operation with respect to all programming of software.
Another object of the present invention is to provide a multipurpose optical intelligent key board apparatus for supporting any language, in addition to a mother native tongue, to be used with respect to all keys on a key board.
Also, another object of the present invention is to provide a multipurpose optical intelligent key board apparatus for enabling all keys on the key board to represent the software command words, thereby functioning as a command word interface.
Another object of the present invention is to provide a multipurpose optical intelligent key board apparatus for supporting the software of a key board itself, in which the arrangement of the key board can be changed to permit all the keys to show computers command words which correspond to the software programming to be used.
Still another object of the present invention is to provide a multipurpose optical intelligent key board apparatus which allows the operation of all keys on the key board as function keys and the operation of corresponding command word keys for the control of a particular electronic appliance.
SUMMARY OF THE INVENTION
The present invention comprises: a key board means receiving all key top means in a predetermined arrangement, a plurality of key top means made of transparent materials, such as epoxy resin, acryl resin, glass or crystal in the form of a cube or a rectangle which cad be switched to represent auxiliary command words and characters; a plurality of light interrupting means for retaining the respective key tops, to block an coherent or incoherent light beam; means for elastically supporting all pairs of a key top means and a light interrupting means, a middle plate made of metal with a configuration the same as that of the key board means and which supports all elastic means and light interrupting means; an optical means for sensing the operation of the key top means during the downward moving of the light interrupting means out of the lower portion of the middle plate to block the light beam; a display means in the form of a Liquid Crystal Display(LCD) or Light Emitting Display(LED) and an optical device in a dot matrix arrangement which is capable of freely changing a character pattern to match the configuration of the key board means having a plurality of key top means according to the application of the software to be used; and an illuminating means including a luminescence emitting plate which operantes by means of a minimum current at the bottom portion of the display means.
Thus, the present invention provides a controllable display means capable of changing a given software program operation to represent a given function key on a corresponding key top to provide an auxiliary character arrangement as well as to operate the corresponding electronic appliance by forcing the light sensing device to interrupt the function of the corresponding key top when it is pressed.
This optical key board apparatus is e to represent all characters used in every language by providing a key board utility software without the necessity of printing characters on all of the key tops according to one unique language.
The optical intelligent key board can also display the role of function keys used in all applied software programs on a LCD or LED and an optical device below the bottom portion of each of the key tops. This display state is visually recognized through each of the key tops made of transparent materials, thereby creating a key board which enhances the user's convenience. As a result, a manual corresponding to each particular applied software is reduced, and the display of the functions of the applied software is maximized to overcome any disadvantage caused by the user's partial knowledge.
The present invention furthermore can provide a multipurpose intelligent key board apparatus compatible with any software programming. The multipurpose intelligent key board apparatus can be adapted to a note-book PC and lap-top computer, so that it may be used like an exclusive use terminal of a word-processor, a data base computer and a spread sheet. It can not only be adapted to the key board of a Position Of System(POS) terminal and a portable telephone, but also to achieve various additional function as well as the reduction of the number of key switches on the key board.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be explained in detail with respect to the attached drawings, in which:
FIG. 1 is a plan view showing the arrangement of a conventional key board corresponding to an AT type computer;
FIG. 2 is a view illustrating the arrangement of optical couplers adapted to the principle of the present invention;
FIG. 3 is a view illustrating the adaption of the switching functions of the key tops to a dot matrix according to the principle of the present invention;
FIG. 4 is a schematic view illustrating the display state of the function key tops according to the principle of the present invention;
FIG. 5 is an exploded perspective view illustrating important components when the present invention is adapted to an AT type key board;
FIGS. 6A and 6B are cross-sectional views illustrating the assembly of the present invention, in which FIG. 6A illustrates the state of a key top when fitted into a light interrupting device;
FIG. 6C is a perspective view of a key top and optical interrupting device according to the invention;
FIG. 7 and FIG. 8 are plan views illustrating the arrangement of a key board adapted to the English/Korean language word-processor according to the present invention; and
FIG. 9 and FIG. 10 are exploded perspective views illustrating the control key board of an electronic appliance according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows parts of a conventional AT type key board adapted to the IBM PC, which includes an arrangement of both Korean and English characters. The key board is provided with a plurality of key top groups 10, 12, 14, 16, 18. . . each arranged by line, each group consisting of key tops on which corresponding characters are printed. For example, the key top group 10 in the first line is arranged so that the key tops respectively represent FIGS. 1, 2. . . and the predetermined alternate characters , @. . . which are selected by using the SHIFT key. The key top group 12 has key tops in one line which represent the English capital letters Q, W, E. . . and alternate Korean characters, which are selected by using the SHIFT key, and the English lower case q, w, . . . and alternate Korean characters which are selected without the SHIFT key. The ALT key of the key top group 18 performs a special function when used in combination with one of the other key tops.
These key top switches on the conventional key board let their upper plan portion be printed upon with the predetermined corresponding characters or are doubly moulded to have the predetermined corresponding characters. The configuration of the key top switches may be variously adapted to the mechanical contact type, the electrostatic capacity change type or the membrane type, etc. However, even though only one of the key top switches, becomes out of order, the key board can only be repaired by being totally disassembled.
In light of these points, the present invention includes a plurality of key top switches located in a transparent rectangular or other predetermined shape using materials, such as glass, acryl, plastic or crystal. These materials are able to transmit the light by optical refraction to create visible characters, graphs and figures represented in a display device such as a LCD screen which is positioned below the keyboard bottom surface, thereby creating the same effect as those on the printed key board. Thus, a light transmitting key board is constructed in order for its key tops of transparent materials to visually display characters, graphs and figures represented by a display device in either the original proportion or in a reduced or enlarged proportion by means of optical refraction.
First, the key tops are respectively coated or covered on their vertical lower side surfaces by opaque materials, so that they are positioned in a horizontal plane at X and Y coordinates like a matrix arrangement of more than 6*32 consisting of infrared ray receiving and emitting elements, thereby detecting the light blocking positions. The transparent key tops also are coated on their vertical surfaces by opaque materials, and an optical wave guider of transparent materials is positioned therebetween to guide infrared rays, thereby detecting the displacement of the key stroke to cause a sensing device to read the scan code on the X and Y coordinates.
According to the principle of the present invention, the key top switches are arranged as shown in FIG. 2, in which the vertical columns and horizontal rows form a matrix. A computer key board is similarly arranged in 6 columns * 32 rows of a minimized unit. The key matrix 20 has a light emitting diode group 21 positioned in the right columns of the drawing and a photo-transistor group 22 consisting of light receiving elements located in the left columns along the same line as the light emitting diodes. Also, a photo-transistor group 23 is arranged in the upper rows and a light emitting diode group 24 in the lower rows corresponding to the light receiving light elements. These arrangements form a switching matrix of columns V1 to V6 and rows H1 to H5 as shown in FIG. 3. It is based on the concept illustrated in FIG. 4.
Assuming that function key tops F1 to F12 are associated with an AT type key board is adapted to the software of a predetermined word-processor, the key top F1 or 31 a key top HELP, the key top F2 or 32 is a key top ASSIST, the key top F3 or 33 is a key top APPEND, and the key top F6 or 35 is a key top EDIT; each are made of transparent materials to represent a predetermined corresponding function. Below the bottom surface of these key tops a light emitting element group 21 and a photo-transistor group 22 receiving infrared rays are mounted in a matrix arrangement. The optical coupler groups 21 and 22 are provided with function key tops 31 to 35 which function as optical switches, on each of which opaque material or light interrupting devices 41 to 45 are mounted in the same line with the photo-coupler groups. An LCD type display device 112 is mounted below the bottom surface of light interrupting devices 41 to 45 to enable the function key tops 31 to 35 to represent the corresponding information as described in detail below.
A typical example of the present invention adapted to a computer key board is illustrated in FIGS. 5, 6, 7 and 8. A typical example of the present invention adapted to a telephone key board or calculator key board of an electronic appliance is illustrated in FIGS. 9, 10 and 11.
Referring to FIG. 5, a multipurpose optical intelligent key board apparatus 100 comprises a key board front plate 102 having a plurality of holes 101 for receiving corresponding key tops, respectively, which are arranged in a predetermined matrix. The key tops 104 are made of transparent materials, such as acryl resin, plastic, glass or crystal, in the form of a rectangular shape as shown in the drawing or another geometrical shape. The key top 104 is fitted into an optical interrupting device 105 constructed to wrap around its periphery at a predetermined height, in which the optical interrupting device 105 is made of metal or any other material capable of interrupting lightly.
The optical interrupting device 105 is provided with a flange 107 horizontally extended at the predetermined height from each surface of the key top 104, in which the predetermined height is set to allow the flange 107 to be elastically supported on the lower surface of the key board front plate 102 and to be contacted with a middle plate 108 when the key top 104 is pressed.
A leaf spring or coil spring 106 is supported on the middle plate 108, which has relatively small holes 109 formed in the same arrangement as that of holes 101 and 103. . . on the key board front plate 102, in order to elastically retain the key tops 104 together with the optical interrupting device 105. A plurality of optical guiders 110 are mounted adjacent to the bottom surface of the middle plate 108. A plurality of optical couplers are mounted to the optical guiders around the periphery of the key board front plate 102. The optical guiders 110 are configured to have the same arrangement as that of the holes 101 of the key board front plate 102, in such a manner that the photo-coupler groups, including the light emitting diodes and photo-transistors, are disposed on the front and rear portions and the left and right portions of the key board front plate 2. The drawing illustrates three light emitting diodes of the lower light emitting diode group 24 and one light emitting diode of the left light emitting diode group 21. In addition, the optical guiders 110 are configured to receive all optical interrupting devices 105 related with the respective key tops 104. A flat LCD type display device 112 is located below the bottom surface of the optical guiders 110 so that it can be divided to conform to the arrangement of the holes 101 on the key board front plate 102 to display the character or function of the key tops 104.
The liquid crystal display device 112 may be a dot matrix liquid crystal plate which displays information of the function key tops and the character key top according to the software programming. The liquid crystal display device 112 may have a luminescence plate 113 on its lower portion to meet the user's needs with respect to the background color.
All these components may be assembled into a base plate 114, and then the base plate 114 is coupled with the key board front plate 102 to complete the assembly of the multipurpose optical intelligent key board apparatus 100.
Specifically, as shown in FIGS. 6A, 6B, and 6C, a key top 104 is projected upward through a key board 102 while being supported by a leaf spring 106 between a middle plate 108 and a flange 107. An optical guider 110 is fixed to the lower surface of the middle plate 108. A display device 112, a luminescence plate 113 and a base plate 114 are arranged in order below and spaced from the bottom surface of the optical guider 110.
The multipurpose optical intelligent key board apparatus 100 can display information of the function/character key tops according to the software programming to be used as illustrated in FIGS. 7 and 8. Referring to FIG. 7, the functions of key tops 31, 32, 33, 34. . . illustrate its corresponding function in Korean characters, the figure key top group 10 represents only figures, the character key top groups 12 and 14 show the key functions corresponding to Korean characters and the key tops SHIFT and ALT of the other character key top groups 16 and 18 permit the corresponding functions to be visually perceived. The Korean display key tops may be represented in English as shown in FIG. 8. An explanation with respect to FIG. 8 is omitted because it is the same as the explanation for FIG. 7.
FIGS. 9 and 10 illustrate examples adapted to an electronic appliance, in which FIG. 9 is an exploded view of a calculator, and FIG. 10 is an exploded perspective view of a key board adapted to an electronic appliance.
The important components shown in FIGS. 9 and 10 are the same as those of FIG. 5, for which the same components are referenced by the same numbers, and their detailed explanation is omitted. The differences between FIG. 5 and FIG. 9 consist of the photo-transistor group 22 which includes a plurality of light receiving elements arranged in opposition of a light emitting diode group 21 including a plurality of light emitting elements, and a liquid crystal display device 112 displays characters associated with information corresponding to the key tops. The configuration of FIG. 10 is the same as that of FIG. 9, except that a leaf spring for elastically supporting key tops 104 is replaced by an elastic spring 106.
INDUSTRIAL APPLICABILITY
As described above, the present invention strengthens the support of a software program by use of to a liquid crystal display device for displaying not only the command words of the software but also the characters to be used, in which the key board connected to a computer is supplied with information about the function keys and character keys. Thus, the present invention can assist in the operation of the programming associated with a computer or an electronic appliance by providing users with optical representations of characters and functions on a plurality of key tops.
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A multipurpose optical intelligent key board apparatus permitting a plurality of key tops made of transparent materials in an optical dot matrix arrangement to be moved upward and downward. It forces the corresponding positions of the optical dot matrix to be turned on or off, so that a computer or an electronic appliance can be operated by predetermined key inputs. Therefore, the function command words and characters appearing on the key tops are displayed by a display device supported by its software.
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BACKGROUND OF THE INVENTION
The invention described herein was made in the course of work under Grant No. DMR-82-13794 from the National Science Foundation. The U.S. Government has certain rights in this invention.
This application is a continuation-in-part of U.S. Ser. No. 775,761, filed Sept. 13, 1985, now abandoned, the contents of which are hereby incorporated by reference into the present application.
Throughout this application various publications are referenced by arabic numerals within parentheses. Full citations for these references may be found at the end of the specification immediately preceding the claims. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art as known to those skilled therein as of the date of the invention described and claimed herein.
Attempts have been made in the past to synthesize polymers like A, in which conjugated arrays and metal atoms alternate. One such attempt resulted in the formation of compounds in which the bonds created in the polymerization process were between carbon atoms and when applied to preparations of polyferrocenylenes (structure B) gave small oligomers that were well characterized (14) and larger polymers that were sometimes impure (15, 16).
In other experiments, the carbon-metal bonds were created in the polymerization process, and when applied to reactions of transition metal salts with dilithium asindacenide (C) gave (C 12 H 8 M) n , where M is Fe, Co, or Ni; with dilithium pentalenide (D) (C 8 H 6 M) n (here M=CO or Ni), and with dilithium fulvenide (E) (C 10 H 8 M) n , where M=Fe, Co, Ni or Mo. However, the value of n in each of these experiments was 2, i.e. the products were only dimers. ##SPC3##
A hypothesis for avoiding dimerization was presented. This idea involved incorporating the hydrocarbon sandwiches of the dimers within helicenes. Conjugated helical hydrocarbon dianions capped by five-membered rings were synthesized for the purpose. It was suggested that reacting these aromatic anions with transition-metal halides would produce metallocene polymers. However, the aromatic dianions produced were too small to give polymers.
Dimers can form only when the number of extending benzene rings is few. Monomeric metallocenes (structure F where M=Fe, Co + PF 6 - ) are formed when the five-membered rings superimpose overlapping unsaturated five-membered rings which can yield polymeric metallocenes. ##SPC4##
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 depicts the 75 MHz 13 C NMR spectrum of the oligomer having structure H in CD 3 COCD 3 . The spectrum, measured using 90° pulses and no relaxation delay, is displayed with 5 Hz line broadening. The chemical shifts were measured assuming that of CD 3 COCD 3 to be 29.8 ppm. Peaks assigned to metallocene carbons are pointed out, and the dotted arrows show where the corresponding resonances appear for the indene analogue (pictured). The peak marked C m is attributed to the methylene carbon (labeled on the diagram).
FIG. 2 depicts the 200 MHz 1 H NMR spectrum of the helicene having structure G in CDCl 3 .
FIG. 3 depicts the 13 C NMR spectrum of the helicene having structure G in CDCl 3 . The resonances of carbons of the five-membered ring are assigned to peaks at 40.2, 130.5, 132.4, 137.7 and 142.9 ppm (see reference). The seven protonated benzenoid carbons are assigned to peaks at 119.6, 122.9, 126.0, 126.3, 126.4, 126.5, and 128.1 ppm. Five of the six quaternary benzenoid resonances are visible: 126.2, 128.5, 130.3, 130.9, and 132.3 ppm.
FIG. 4 depicts the CD (solid line) an UV (broken line) spectral of the helicene having structure G (6.17×10 -6 M) in CH 3 OH. UV peaks (log ε) are at 354 (4.05), 336 (4.16), 278 (4.73), and 252 nm (4.84). CD peaks ([θ]) are at 243 (6.48×10 4 ), 285 (1.75×10 5 ), and 395 nm (-1.0×10 5 ).
FIG. 5 depicts the CD (solid line, 5×10 -6 M) and UV (broken line, 5×10 -6 M) spectra of the oligomer having structure H (M=Co + PF 6 - ) in CH 3 CN. UV peaks (log ε) are at 486 (4.41), 340 (4.66), and 258 nm (5.11). CD peaks ([θ]) are at 263 (3.30×10 6 ), 382 (-1.19×10 6 ), and 474 nm (-8.40×10 5 ).
FIGS. 6A and B depicts the chemical reaction and products of each step described in Examples 1-11.
SUMMARY OF THE INVENTION
The present invention concerns a helicene compound having the structure: ##SPC5##
which contains seven six-membered conjugated aromatic rings capped by two five-membered rings which do not superimpose on each other.
The present invention also concerns a helical metallocene oligomer capped by unsaturated five-membered rings, having the structure: ##SPC6##
wherein M is a transition metal halide and n=1 to 100.
A method of preparing the helicene is provided which comprises:
(a) contacting a compound having the structure: ##STR1## wherein R=(t-Bu)Me 2 Si, with 1,4-bis[(C 6 H 5 ) 3 P+CH 2 ]-2-Br--C 6 H 3 , under suitable conditions to form a compound having the structure: ##STR2## (b) then, subjecting the compound formed in step (a) to light energy in the presence of an acid scavenger compound which results in a photocyclization; and
(c) finally, contacting the cyclized product of step (b) with a suitable reducing agent and an acid to form the helicene.
A method of preparing the helical metallocene oligomer is also provided which comprises:
(a) first, contacting the helicene prepared as described above with a suitable base;
(b) contacting the product resulting from step (a) with a transition metal halide in a suitable solvent;
(c) contacting the product of step (b) with a suitable oxidizing agent; and
(d) contacting the product of step (c) with a hexahalophosphate salt to produce the helical metallocene oligomer.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a new composition of matter, a polymer comprised of alternating metal atoms and rings of atoms in which the path of conjugation of so-called π-electrons extending from one metal to the next is unbroken either by atoms that do not have available a single η-electron to continue the path of conjugation or in which the carbon skeleton does not constrain the π-electrons on adjacent atoms to almost parallel orbitals. The π-electrons are those valence shell electrons on the skeletal atoms in excess of the one required to bond to each adjacent atom. The invention includes those examples of materials in which the skeleton is coiled in a helix, and those examples in which one of the two directions predominate in which the helices wind. It includes examples of the materials described in the first sentence above that are optically active.
It is contemplated that the metals useful in the present invention are any metals chosen from among the transition elements (i.e. groups 3-10 of the most recent revision of Mendeleev's Table of the Elements), the lanthanides or the actinides.
An example of the present invention is the polymeric cobaltocinium hexafluorophosphate shown below. ##SPC7##
Foreseeable uses of the materials of the present invention include those exploiting the electrical, magnetic, and optical properties of the materials and their derivatives. The metallocenes of the present invention may also be the basis for new catalysts that induce high asymmetry in chemical transformations. ##SPC8##
a 1,4-bis[(C 6 H 5 ) 3 P + CH 2 ]-2-Br--C 6 H 3 , 2Br - (0.5 equiv wt), LiOEt (1.1 equiv wt), EtOH, 25° C., 5-12 h, 95-100% yield). b h, C 6 H 6 , I 2 (2.2 equiv wt), propylene oxide, 4-12 h. c (1) t-BuLi, tetrahydrofuran, 78° C.; (2) H 2 O; (3) p-toluenesulfonic acid, C 6 H 6 , 80° C., 10 min (45-65% yield from J).
The preparation of hydrocarbon G, summarized in Scheme I, is easy to carry out (7). The phosphonium salt of step a was prepared from 2-bromo-p-xylene (2.2 equiv. N-bromosuccinimide, 0.008 equiv. dibenzoylperoxide, CCl 4 , reflux, 3h, 75% yield, then 2 equiv. triphenylphosphine in DMF, 91% yield. All new compounds exhibited satisfactory NMR, IR, and (except for the salts), mass spectra (including, for key compounds, high resolution mass spectra). In the 1 H NMR spectrum of G, as in other helicenes, the olefinic and allylic proton resonances are shifted to higher field than in simpler indenes (1, 3b, 7). The isomers of J in which both ether functions are in the other benzylic position do not give appreciable amounts of helical product, and the one in which the ethers are in the non-benzylic position gives a helical product from which the ethers cannot be eliminated (7).
The method of preparation has three main features. (1) A bromine directs the photocyclization to give the helix by blocking both the position it occupies (C-1) and the position adjacent (C-2) (5). This atom is then easy to remove. In its absence, the cyclization gives only the planar isomer L and none of the helicene G. Resonances characteristic of G are absent in the 1 H NMR spectrum of the crude product (7). Propylene oxide is required during the photocyclization to consume the HI generated, thereby preventing the ROH functions from being eliminated prior to cyclization (7). In the absence of propylene oxide, photo-cyclization of (R,R)-K gives helical product, but in a racemic form (7). The direction in which the helix winds is that expected if silyloxyls outside the helix are favored. The helicity is thus controlled by the stereochemistry of I (7).
J is prepared from (R)-I [46-52% enantiomeric excess (ee)] and irradiated in the presence of traces of iodine, it gives helical bis-indene (containing the bromine) whose [α] D (+82°) corresponds to ca. 1% ee. The double bonds in this material are shifted from their position in G (7).
For the absolute configuration of (S)-(-)-I see ref. 7. The absolute configuration of G was assigned on the assumption that, like all helicenes, the (M)-enantiomer is levorotatory at 578 nm and exhibits a negative Cotton effect in its CD spectrum in methanol for the band at 395 nm ([α]=-1×10 5 deg cm 2 mol -1 ) (7). Its ee was measured by analyzing the 1 H NMR resonances of one of its CH 2 's when a solution (2.5 mg) in CDCl 3 (1 mL) contained Ag(fod) (4 mg) and Eu (hfc) 3 (12 mg) (7). The rotation of a sample, [α] D =4200°, measured to have an ee of 60% implies that [α] D max =7000°.
Structure (S,S)-J is contacted, e.g. mixed in a suitable solvent, contacted with a suitable reducing agent (e.g. t-BuLi) which eliminates the bromine group and then contacted with an acid (e.g. p-toluene sulfonic acid) which eliminates the RO-groups and introduces two double bonds. (S,S)-J of Scheme I gives 27% structure Ka (recognized by the symmetry of the 1 H NMR after debromination), 12% Kb, and no detectable ( 1 H NMR) endo, endo isomer. The latter could not have been misassigned the exo, exo-structure since the (M)-configuration requires more asymmetric carbons to have the (R)-stereochemistry than are present in J (7).
When the helicene G is combined first with t-butyllithium and then with CoBr 2 .DME (DME=1,2-dimethoxyethane) and the product is oxidized in aqueous HCl with FeCl 3 , added NH 4 PF 6 precipitates a red cobaltocinium salt (69% yield after washing with water and ether, and drying) that elemental and spectroscopic analyses indicate to be an oligomer of structure H (M-Co + PF 6 ) (7, 8). The anion of the salt of the hexaflurophosphate (PF - 6 ) substitutes for the bromines of CoBr 2 . This material is soluble in acetone and acetonitrile, and was purified by adding its solutions in acetone to vigorously stirred ether, then filtering and drying the resulting precipitate. It is unaffected by heating in air at 260° C.
Evidence that the cobaltocinium salt is a short polymer of structure H is the following. The 13 C NMR spectrum (FIG. 1) consists of resonances at positions characteristic only of benzenoid helicenes (including G) (135-118 ppm), (10) of bis(indenyl)cobalt(III) salts (80-74 ppm), (11) and of the methylene group of G (40 ppm, this last peak very small, corresponding to approximately two end groups for every 3-4 cobalts) (11). FIG. 1 marks (with dotted arrows) the positions at which the carbon atoms of the five-membered rings of bis(indenyl)cobalt(III) hexafluorophosphate exhibit their resonances, and it shows that the corresponding peaks attributed to structure H are all 2 ppm to their right. This shift is expected, for when comparing the resonances of carbon-2 in [4]- and [7]-helicenes, (the second protonated carbon on the first ring counting from the inside of the helix) the latter (in which this carbon is above another ring) is shifted to higher field by 2 ppm (10). Another significant feature of the spectra is the absence of resonances around 51.3 ppm, characteristic of 1,1'-bi- 1 H-indene ["bi(3-indenyl)"], showing that the transition metal ions do not couple the carbanions by oxidation.
The elemental analysis corresponds to a composition of 3.13 hydrocarbons, 2.13 CoPF 6 's, and 3.45±1.4 H 2 O's. The molecular weight is thus ca. 1.9×10 3 . Three independently prepared samples were analyzed. Anal. calcd. for 2.0 H 2 O's: C, 71.65; H, 3.66; Co, 6.65. Found: C, 71.24; H, 3.90; Co, 6.71. Anal calcd. for 4.9 H 2 O's: C, 69.93; H, 3.88; Co, 6.49. Found: C, 69.82; H, 3.73; Co, 6.48. The third sample's analysis corresponded to that of a slightly larger molecule. Anal. calcd. for 3.49 rings, 2.49 CoPF 6 's, 7.3 H 2 O's: C, 67.96; H, 3.92; Co, 6.61; F, 12.78. Found: C, 68.18; H, 3.61; Co, 6.63; F, 12.45. For a simple complex of 2 rings and 1 Co, calcd. is C, 77.84; H, 3.81; Co, 5.30; and for an infinite polymer, C, 65.89; H, 3.07; Co, 8.97.
The optical activity is very high, 4.1 (±0.6) times as great as that of G. When measured using a sample prepared from G whose enantiomeric excess (ee) was 60%, [α] D for cobaltocinium salt of 100% ee is 26,000. The molar ellipticities of the CD peaks at 474 and 263 nm (-8.4×10 5 and -3.3×10 6 , assuming the molecular weight to be 1.9×10 3 ) are 7.2 and 6.0 times as large as for the corresponding peaks in F (M=Co +PF 6 - ) (7).
The present invention is further illustrated by reference to the examples which follow. These examples are keyed to the reactions and structures depicted in FIG. 6.
EXAMPLE 1
In an oven-dried 2 L 3-necked round-bottomed flask, fitted with a mechanical stirrer, an argon inlet and a 250 mL dropping funnel, was placed 114.4 g (0.4 mol) 2,7-dibromonaphthalene (FIG. 6, Structure N) and 1 L freshly distilled THF. The solution was stirred and cooled to -78° under argon. A solution of n-butyllithium (175 mL 2.4M, 0.42 mol) in hexanes was injected into the addition funnel and added in drops in 30 min. The greenish-yellow mixture was stirred at -78° C. for another 20 min. Dry chlorotrimethylsilane (81 mL, 69.5 g, 0.64 mol, distilled from CaH 2 ) was then added in 10 min from the dropping funnel, resulting in an exothermic reaction and a color change to orange. After the exotherm subsided (ca. 15 min), the cooling bath was removed and the mixture was allowed to warm to room temperature and stirred for 2 h. Solvent was evaporated to about 250 mL and the mixture was diluted with 1 L of water. It was then extracted with ether (1×600 mL, 3×100 mL ether). The combined ether extracts were washed with 200 mL brine, dried over anhydrous magnesium sulfate, and filtered. Evaporating the solvent gave 126 g (112%) yellow-orange liquid, which when kept at 15° C. overnight solified to a pale yellow mass. This crude product is pure enough for the next step, although the results of that step imply that 2-bromonaphthalene is present as an impurity.
1 H NMR (200 MHz, CDCl 3 ): δ7.99 (dd, J=1.5, 0.8 Hz, 1.01H), 7.88 (d, J=0.8 Hz, 0.96H), 7.77 (d, J=8.1, 1.2 Hz), 7.67 (d, J=8.7 Hz), 7.58 (dd, J=8.1, 1.2 Hz), 7.52 (dd, J=8.7, 2.0 Hz)--the integral of 7.77-7.52 corresponds to 4.4H--0.32 (s, 8.6H).
EXAMPLE 2
Anhydrous aluminum chloride (70 g, 0.526 mol, Fisher) was placed in a 1 L 3-necked flask fitted with a mechanical stirrer, nitrogen inlet, and 250 mL addition funnel. Dichloromethane (100 mL) and a solution of 61 g (0.48 mol) 3-chloropropionyl chloride in 50 mL dichloromethane were added to the flask while its contents were stirred. The flask was cooled in dry-ice acetone, and a solution of 126 g bromosilane (FIG. 6 structure Q) in 200 mL dichloromethane was added in 35 min. The mixture was stirred for 10 min at -78° C. and allowed to warm to room temperature during 45 min. The reaction mixture was poured into ca. 1000 mL ice containing 100 mL conc. hydrochloric acid. The mixture was extracted with 1.5 L dichloromethane, and the aqueous layer was extracted with additional dichloromethane (3×200 mL). The combined organic layers were washed once with 1.5 L water, dried (MgSO 4 ), filtered, and evaporated to give 135 g crude structure P as an off-white solid. This was cyclized without further purfication. However, it could be purified by shaking with 500 mL petroleum ether and filtering. The precipitate was then pure structure P (90 g, 76%), and the filtrate on evaporation gave 44 g of dark liquid containing some structure P.
For the pure material the m.p. is 120° C. and the 1 H NMR (200 MHz, CDCl 3 ): δ: 8.35 (br s, 0.79H), 8.12 (d, J=0.95 Hz, 0.79H), 8.02 (dd, J=8.6, 1.7 Hz, 1.11H), 7.87 (d, J=8.6 Hz, 1.05H), 7.75 (d, J=8.9, 1.05H), 7.66 (dd, J=8.8, 1.8z, 1.05H), 3.96 (t, J=6.9 Hz, 2.10H), 3.56 (t, 6.9 Hz, 2.10H).
EXAMPLE 3
Method A: Anhydrous AlCl 3 (35 g, Fisher) was weighed into an oven-dried 2 L 3-necked flask fitted with a mechanical stirrer, a drying tube the outlet of which is vented to the hood, and a stopper. Concentrated sulfuric acid (325 mL, Mallinckrodt, Electronic grade) was added, and the mixture was stirred in an ice-water bath. Crude structure P (65 g) was added to the suspension in small portions in 20 min while stirring vigorously. The reaction mixture became yellow and then orange. The stopper was replaced in a thermometer and the flask was heated by means of a mantle. When the internal temperature was 65° C., the stirring rate was increased, and rate of heating decreased to control the foaming. After the foaming had subsided, the mixture was held at 98° C. for 1 h. It was then cooled to ca. 70° C., and cautiously poured into 4 L of ice-water containing ice. The mixture was stirred for 2 h and extracted with CH 2 Cl 2 and filtered through a 6"×5 cm column of neutral alumina, eluting with CH 2 Cl 2 . The filtrate was evaporated, giving 38.7 g (68% from P, 76% from N) O as a pale yellow solid, m.p. 131°-132° (lit. 132°-134° C.) (3b). The 200 MHz 1 H NMR is identical with that of a sample prepared according to the previously published procedure (3b). The IR spectrum also was identical to that reported for structure O (3b). Purification of crude O may also be achieved by crystallization as shown below.
Method B: 89.5 g of purified P was added over 40 min to 300 mL concentrated sulfuric acid in a 2 L 3-necked flask (the apparatus was the same as in method A above). The reaction mixture was heated to 90° C. (internal temperature) and maintained at this temperature for 80 min. After cooling, the reaction mixture was poured into ice-water, extracted with CH 2 Cl 2 (15×200 mL), the organic layer washed with 2 L water, dried (MgSO 4 ), filtered and evaporated. The residue was crystallized from CH 2 Cl 2 -ether, giving 61 g off-white solid. A second crop of O, 15 g was obtained after chromatography of the mother liquor. The total yield of O, 76 g, represents a 73% yield from 2,7-dibromonaphthalene.
EXAMPLE 4
Lithium aluminum hydride (8.05 g, 0.2 mol, Aldrich) and dry ether (100 mL) were placed in a 2 L 3-necked flask fitted with mechanical stirrer, 250 mL Kontes addition funnel and a dry condenser carrying a N 2 inlet. To the stirred suspension was added during 20 min a solution of 35.8 g (0.2 mol) (+)-N-methylephedrine in 350 mL dry ether. The reaction mixture was refluxed for 1 h, cooled, and a solution of 48.9 g (0.4 mol) 3,5-dimethylphenol (Aldrich) in 220 mL dry ether was added over a period of 225 min. The mixture was again refluxed for 1 h, cooled in ice-salt-water mixture (internal temp. 0° C.), and 20 g O was added in one portion. The mixture was stirred overnight.
Water (10 mL) was added in drops to the reaction mixture, followed by 400 mL 1M hydrochloric acid. After 5 min, the ether layer was separated and the aqueous layer extracted with 200 mL ether. The combined ether layer was washed with 1M HCl (1×300 mL), water (1×200 mL), 10% NaOH solution (3×200 mL), brine (1×500 mL), and dried over MgSO 4 . The solvent was then evaporated to a small volume, and the solid was filtered giving 11.5 g R, [α] 578 20 =-43° (c=0.40, CH 2 Cl 2 ). A second crop (4.1 g, [α] 578 20 =-0.56° (c=0.36, CH 2 Cl 2 ) was obtained from the filtrate when pentane was added. Evaporation gave a third portion, 4.3 g [α] 576 20 =-9.2°. The NMR spectrum of R was identical to that of its racemate (3b). The results of two related experiments are these:
(1) from 32.6 g ketone there were obtained 23.4 g R with [α] 578 =-40°, 4.3 g R with [α] 578 =-2°, and 4.8 g R with [α] 578 =-12.4°; (2) from 32.6 g ketone, 24.3 g R with [α] 578 =-41.2° (ee=46%) and 10.2 g R with [α] 578 =-6.67°.
The NMR spectra of the O-methylmandelate ester (12) and the CD spectrum of the p-bromobenzoate ester (13) show that the (-)-enantiomer has the (S)-configuration.
EXAMPLE 5
S-(-)-R (34.9 g, 0.133 mol), [α] 578 20 =-41° (c=0.4, CH 2 Cl 2 ), was mixed with 30 g (0.199 mol) t-butyldimethylsilylchloride (Petrarch Systems) and 28 g (0.412 mol) imidazole (Aldrich) in 400 mL DMF (Fisher, spectroscopic grade). The solution was stirred at room temperature under N 2 for 200 min, diluted with 800 mL ether, and shaken with 2 L cold water. The ether layer was washed with brine (2×500 mL), dried (MgSO 4 ), filtered and evaporated, giving an orange oil that eventually solidified. This was chromatographed on a silica (6"×10 cm dia.) column, eluting with CH 2 Cl 2 -petroleum ether (1:7). The product eluted quickly, and evaporation gave 51 g (102%) white solid, [α] 578 20 =-50° (c=0.2, CH 2 Cl 2 ). The NMR spectrum of this material was identical to that reported for racemic S (3b).
EXAMPLE 6
S-(-)-S (34.2 g, 0.091 mol, [α] 578 =-50°) was dissolved in 1 L dry THF and 0.5 L dry ether in a 2 L 3-necked flask fitted with an Ar inlet, low-temperature thermometer and a septum. The solution was cooled to -78° C. under argon and 80 mL (0.208 mol) of 2.6M n-butyllithium in hexanes was injected through the septum during 5 min. The slightly greenish solution was stirred at -78° C. for 20 min, and then 100 mL dry DMF (distilled from BaO under reduced pressure) was injected. The cooling bath was removed and the solution stirred for 70 min. Quenching with 200 mL water, extraction with 700 mL ether, washing with brine (1 L, 2×0.5 L, re-extracting with 2×400 mL ether) and again with brine (400 mL), drying (MgSO 4 ), and evaporation gave an oil, which was chromatographed on silica. CH 2 Cl 2 -petroleum ether (1:2) eluted an impurity, and CH 2 Cl 2 -petroleum ether (1:1 to 2:1) eluted the aldehyde I, 25.2 g (85%) as a pale yellow solid, [α] 578 20 =-42.7° (c=0.3, CH 2 Cl 2 ). The NMR spectrum of this material was identical to that of racemic I (3b).
EXAMPLE 7
2-Bromo-p-xylene T (46.25 g, 0.25 mol, Aldrich) was mixed with 98 g (0.55 mol) N-bromosuccinimide (Fisher) and 500 mL carbon tetrachloride in a 1 L round-bottomed flask. Dibenzoyl peroxide (500 mg) was added, and the mixture was refluxed for 100 min, cooled, filtered, and the filtrate was evaporated to a small volume. Trituration with pentane gave a precipitate, which was filtered giving 18.5 g white solid, m.p. 86° C. A second crop (20.5 g) was obtained from the mother liquor. The total yield of U was 39.0 g (45.5%).
1 H NMR (270 MHz, CDCl 3 ) δ: 7.60 (d, J=2 Hz, 1H), 7.42 (d, J=7.9 Hz, 1 H), 7.31 (dd, J=7.9 Hz, 2 Hz, 1H, 4.57 (s, 2H), 4.40 (s, 2H).
EXAMPLE 8
The tribromide U (39 g) and 63 g triphenylphosphine were dissolved in 300 mL dry DMF, and the solution was refluxed for 3 h. After cooling, 200 mL ether was added, and the precipitate was filtered. The solid was washed with ether to give V as a white fluffy solid, m.p. 260° C. Yield 89.2 g (91%).
H NMR (300 MHz, CD 3 CN) δ: 7.9-7.8 (m, 6H, 7.7-7.45 (m, 24H), 7.09 (br s, 1H), 7.0-6.95 (dd, J=8.0, 2.4, 1H), 6.9-6.85 (br d, J=8.08), 4.85 (dd, 4H).
EXAMPLE 9
n-Butyllithium (37 mL, 2.4M, 88.8 mmol) was injected into a 2 L 3-necked flask fitted with argon inlet, mechanical stirrer, and an addition funnel. The flask was cooled to -78° C., and 400 mL 200-proof ethanol was added in drops from the funnel during 20 min. The solution was then allowed to warm to room temperature.
The bis(phosphonium) bromide V (35, 0.040 mol) and S-(-)-aldehyde I-(25.2 g, 0.077 mol) were suspended in 500 mL 200-proof ethanol in a 2 L 3-necked flask fitted with an Ar inlet, mechanical stirrer, and a septum. During 30 min the lithium ethoxide solution prepared above was transferred to the solution via a cannula. The resulting yellow solution was stirred overnight, during which a fine yellow precipitate appeared. The suspension was poured into 2 L water, and the mixture was extracted with CH 2 Cl 2 (1×600 mL, 2×300 mL). The CH 2 Cl 2 extract was washed with 1 L brine, dried (MgSO 4 ), and evaporated. The yellow oily residue was chromatographed on silica, eluting with CH 2 Cl 2 -petroleum ether (1:5 to 1:4), giving 31.3 g (100% yield) of yellow solid, [α] 578 20 =-67.8° (c=0.39, C 6 H 6 ).
1 H NMR (200 MHz, CDCl 3 ): δ: 8.0-6.5 (m, 19.4H), 5.45 (br dd, 2.16H), 3.6-2.8 (m, 3.69H), 2.8-2.5 (m, 1.84H), 2.3-1.9 (m, 1.90H), 1.1-0.9 (3 singlets, 16.5H), 0.3-0.15 (m, 10.3H).
IR (KBr, cm -1 ): 2955, 2928, 2889, 2855, 1420, 1461, 1360, 1252, 1105, 1051, 1037, 985, 955, 884, 861, 836, 775.
EXAMPLE 10
(S,S)-(-)-J (200 mg) and 150 mg iodine dissolved in 440 mL benzene (Fisher, spectra-analyzed) was degassed with argon for 20 min and 5 mL propylene oxide was added. The solution was then irradiated for 12 h through a water-cooled pyrex jacket by means of a Hanovia medium pressure Hg lamp. The solvent was evaporated. This experiment was repeated ten times, and the combined residues, dissolved in CH 2 Cl 2 -petroleum ether (1:1), were filtered through a 4" column of neutral alumina. Evaporation gave an orange solid, which was taken up in 100 mL dry THF in a 250 mL round-bottomed flask and cooled to -78° C. under Ar. t-Butyllithium in pentane (10 mL, 1.7M) was added, and after the dark mixture had stirred at -78° C. for 20 min, it was quenched with water and allowed to warm to room temperature. Extraction into 100 mL ether, washing with brine, drying (MgSO 4 ), and evaporation gave a yellow-orange solid, which was dissolved in benzene (100 mL) containing p-toluenesulfonic acid monohydrate (50 mg). The solution was refluxed for 30 min, cooled, extracted with 100 mL ether, washed with saturated NaHCO 3 solution (50 mL) and brine (50 mL), dried (MgSO 4 ), and evaporated giving an oily solid. Chromatography on alumina (silica can also be used) and elution with CH 2 Cl 2 -petroleum ether (1:10 to 1:5) gave 635 mg (56%) of G as a yellow solid, [α] 578 20 -3480° (c=0.015, CH 2 Cl 2 ).
1 H NMR (200 MHz, CDCl 3 ) δ: 7.99 (2, 2H), 7.93 (d, J=8.2 Hz, 2H), 7.69 (d, J=8.2 Hz, 2H), 7.21 (an AB quartet, J=8.6 Hz, 4H), 7.13 (an AB quartet, J=8.0 Hz, 4H), 6.45 (dt, J=5.5, 1.8 Hz, 2H), 5.82 (dt, J=5.5, 1.9 Hz, 2H), 1.91 (dt, J=23.8, 1.7 Hz, 2H), 1.03 (dt, J=23.6, 1.7-2.0 Hz, 2H).
IR (KBr, cm -1 ): 3033(m), 2923(w), 1609(w), 1385(m), 1321(m), 1254(m), 1196(w), 1160(w), 953(m), 839(vs), 775(m), 697(s), 675(m), 637(m), 566(s), 504(m), 403(w).
EXAMPLE 11
M-(-)-J (150 mg, [α] 589 =-3480°) was dissolved under argon in 10 mL dry THF in a 100 mL round-bottomed flask, the solution was cooled to -78° C., and 1 mL 1.6M t-butyllithium was added. The deep brown mixture was stirred at 0° C. for 90 min, cooled to -78° C., and then 105 mg CoBr 2 .DME complex was quickly added against an argon stream. The solution was stirred at room temperature for 2 h and then cooled to -78°. Another 120 mg CoBr 2 .DME was then added. The mixture was stirred at room temperature for 7 h. It was then quenched at 0° C. with a solution of 0.5 mL conc. HCl in 5 mL water. After stirring 2 min, 300 mg ferric chloride hexahydrate (Fisher) was added, and the mixture was stirred overnight. The deep red almost transparent solution was diluted with THF, filtered through celite, and the celite pad was washed with moist acetone. The filtrate was evaporated and the residue washed with ether (3×50 mL, the washings being discarded). The solid was dissolved in acetone-water and after 600 mg NH 4 PF 6 in acetone (5 mL) was added, the solution was concentrated and the precipitate filtered. Washing this precipitate with much water (100 mL) and ether, and drying at 0.005 mmHg gave 150 mg (69%) brick-red solid, [α] 578 20 =-20,300° (c=0.0012, acetone). Purification was achieved by adding a filtered solution of this material in acetone to vigorously stirred anhydrous ether and filtering the precipitate. The optical rotation of purified material was almost the same: [α] 578 20 =-20,400° to 20,800°.
IR (KBr, cm -1 ). 3658(m) and 3585(m, water peaks), 3115(m), 3040(m), 1699(w), 1602(s), 1495(w), 1430(w), 1385(m), 1302(w), 1245(w), 1203(w), 1167(w), 841(vs), 783(m), 731(m), 680(w), 646(w), 558(vs), 472(m), 396(w).
1 H NMR (300 MHz, CD 3 COCD 3 ): 8.3-61 (br m, 14H), 6.1-5.4 (br m, 2H), 5.1-3.9 (br m, 4H).
Elemental analysis: Calculated for (C 36 H 20 CoPF 6 ) n C, 65.85; H, 3.07; Co, 8.98; P, 4.73; F, 17.38 found C, 71.24; H, 3.90; Co, 6.72; F, --; calculated for (C 36 H 21 CoPF 6 ) (C 36 H 20 CoPF 6 ) 2 (C 36 H 21 ): C, 71.35; H, 3.41; Co, 7.65.
REFERENCES
1. Katz, T. J.; Slusarek, W. J. Am. Chem. Soc., 101: 4259, (1979)
2. (a) Katz, T. J.; Schulman, J. J. Am. Chem. Soc. 86: 3169, (1964). (b) Katz, T. J.; Balogh, V.; Schulman, J. Ibid., 90: 734, (1968).
3. (a) Katz, T. J.; Pesti, J. J. Am. Chem. Soc. 103: 346, (1982). (b) Pesti, J. Ph.D. Dissertation, Columbia University, New York, N.Y., (1981).
4. (a) Carraher Jr., C. E.; Sheats, J. E.; Pittman Jr., C. U. "Organometallic Polymers," Academic Press: New York, (1978). (b) Hagihara, N.; Sonogashira, K.; Takahashi, S. Adv. Polym. Sci. 41: 149, (1981).
5. Martin observed a similar effect [Martin, R. H.; Schurter, J. J. Tetrahedron 28: 749, (1972).
6. (a) Martin, R. H. Tetrahedron 20: 897, (1964). (b) Martin, R. H.; Defay, N.; Geerts-Evard, F.; Delavarenne, S. Ibid. 20: 1073, (1964).
7. Sudhakar, A. Ph.D. Dissertation, Columbia University, New York, N.Y. 1985.
8. Kolle, U.; Khouzami, F. Chem. Ber. 114: 2929, (1981).
9. See Treichel, P. M.; Johnson, J. W.; Calabrese, J. C. J. Organomet. Chem. 88: 215, (1975).
10. Defay, N.; Zimmermann, D.; Martin, R. H. Tetrahedron Lett. p. 1871 (1971).
11. Kohler, F. H. Chem. Ber. 107: 570, (1974).
12. B. M. Trost, Chem. Soc. Rev. page 141, (1982) and references cited therein.
13. Koreeda et al., J. Org. Chem., 43: 1023, (1978).
14. (a) Nesmeyanov, A. N. et al. Izv. Akad. Nauk SSSR, Ser. Khim. 667, (1963). (b) Watanabe, H., Motoyama, I.; Hata, K. Bull. Chem. Soc. Jpn. 39: 790, (1966). (c) Roling, P. V.; Rausch, M. D. J. Org. Chem. 37: 729, (1972). (d) Izumi T.; Kasahara, A. Bull. Chem Soc. Jpn. 48: 1955, (1975). (e) Bednarik, L.; Gohdes, R. C.; Neuse, E. W. Transition-Met. Chem. 2: 212, (1977).
15. Metallocene polymers and their conductivities are discussed in (a) Neuse, E. W.; Rosenberg, H. Rev. Macromol. Chem., Part 1, 5, (1970). (b) Lorkowski, H.--J. Fortschr. Chem. Forsch. 9/2: 207, (1967).
16. (a) Bilow, N.; Landis, A. L.; Rosenberg, H. J. Polym. Sci., Part A-1 7: 2719, (1969). (b) Neuse, E. W.; Crossland, R. K. J. Organomet Chem. 7: 344, (1967).
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The invention describes a helicene compound having the structure ##SPC1##
which contains seven six-membered conjugated aromatic rings capped by two five-membered rings which do not superimpose on each other.
The invention also describes a helical metallocene oligomer capped by unsaturated five-membered rings, having the structure: ##SPC2##
wherein M is a transition metal halide and n=1 to 100.
Method for the preparation of these compounds are also presented.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to efficient means for the generation of electrical or other power utilizing energy from geothermal sources and, more particularly, relates to arrangements for suspending efficient super-heated steam generation and hot water pumping equipment in deep, hot water wells for the transfer of thermal energy to the earth's surface.
2. Description of the Prior Art
A prior art advance in the art of extraction and use of geothermal energy is reflected in the H. B. Matthews U.S. patent application Ser. No. 300,058 for a "Geothermal Energy System and Method", filed Oct. 24, 1972, issued July 23, 1974 as U.S. Pat. No. 3,824,793, and assigned to the Sperry Rand Corporation. This prior Matthews invention provides means for efficient power generation employing energy derived from geothermal sources through the generation of dry, super-heated steam and the consequent operation of sub-surface equipment for pumping extremely hot well water at high pressures upward to the earth's surface. Clean water is injected at a first or surface station into the deep well where thermal energy stored in hot solute-bearing deep well water is used at a second or deep well station to generate super-heated steam from the clean water. The resultant dry super-heated steam is used at the well bottom for operating a turbine-driven pump pumping the hot solute-bearing well water to the first station at the earth's surface, the water being pumped at all times and locations in the system at pressures which prevent flash steam formation. The highly energetic water is used at the surface or first station in a binary fluid system so that its thermal energy is transferred to a closed-loop surface-located vapor generator-turbine system for driving an electrical power alternator. Cooled, clean water is regenerated by the surface system for re-injection into the well for operation of the steam turbine therein. Undesired solutes are pumped back into the earth via a separate well in the form of a concentrated brine.
SUMMARY OF THE INVENTION
The invention is an improvement facilitating ready installation and reliable operation of geothermal systems of the kind described in the prior Matthews patent; according to the invention, there are provided novel means for the support of the deep well geothermal pump system within the well casing pipe from the earth's surface by the pump-driving turbine exhaust steam conduit. In view of the differential expansion effects on the relative lengths of the casing pipe extending downward from the earth's surface and the exhaust steam conduit contained therein, a novel flexible seal is provided between the suspended geothermal pump system and the well pipe casing. A first element of the improvement provides a vertical smooth cylindrical sealing surface at the desired location for the deep well apparatus by means itself fully sealed to the well casing pipe. A second element assures easy assembly of a second seal interfacing the cylindrical sealing surface and suspended from the hot water pump so as to permit sliding motion of the seal in the hostile prevailing environment, yet affording reliable sealing action.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation view, mostly in cross section, of the novel suspension arrangement of the deep well geothermal pumping apparatus.
FIG. 2 is an elevation view, mostly in cross section, of the deep well geothermal pump apparatus and of the novel sealing arrangement.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1 and 2 illustrate the general structure and characteristics of that portion of the geothermal energy extraction system which is immersed in a deep well extending into strata far below the surface of the earth, preferably being located at a depth below the surface such that a copious supply of extremely hot water under high pressure is naturally available, the active pumping structure being located adjacent the hot water source and within a generally conventional well casing pipe 10. The configuration in FIG. 1 is seen to include a well head section 1 located above the earth's surface 11 and a main well section 2 extending downward from well head section 1 and below the earth's surface 11. At the subterranean source of hot, high pressure water, as shown in FIG. 2, the main well section 2 joins a steam generator input section 3. The steam generator section 4, the steam turbine section 5, a rotary bearing section 6, and a hot water pumping section 7 follow in close cooperative succession at increasing depths. At the lowest or seal section 12, the input to the pump section 7 is sealed to the inner wall of well casing pipe 10, as will be further described.
Referring again to FIG. 1, the well casing pipe 10 extends downward from the well head section 1 in preferably concentric relation about an innermost stainless steel or other high quality alloy pipe or conduit 8 for supplying a flow of relatively cool and relatively pure water at the bottom of the well. A second relatively large pipe or conduit 9 of similar quality surrounding pipe 8 is also provided within well casing 10, extending from well head 1 to the energy conversion and hot water pumping system at the bottom of the well and permitting turbine exhaust steam to flow to the surface of the earth.
The clean water injection pipe 8 passes through a fitting 13 mounted on the apertured capping plate 14. In similar manner the exhaust steam return pipe 9 passes through a fitting 15 mounted on the apertured capping plate 16. While these generally concentric structures may be integrated to a degree, it is intended that the exhaust steam pipe 9 furnish the main support for the deep well apparatus. For this purpose, a ring collar 17 is welded or otherwise affixed about the exhaust steam pipe 9 immediately below its tee branch 9a. Ring collar 17 normally rests on a suitable horizontal platform 18 which may, in turn, be supported by braces such as braces 19, 20 from associated vertical support beams such as beams 21, 22. The latter are fixed in the earth, for example, by suitable concrete foundation elements (not shown) that may take entirely conventional form. In this manner, the weight of the conduits within the well casing pipe 10 and the weight of the deep well geothermal pump apparatus itself are primarily suspended from the exhaust steam return pipe 9 by platform 18.
It will be seen from FIGS. 1 and 2 that relatively clean and cool water is pumped by pump 37 through pipe 8a into the vertical injection pipe 8 down to the pressure regulator and input section 3 (FIG. 2). As in the aforementioned Matthews patent, the water flow in pipe 8 is then divided for further downward flow in two branching pipes (not shown). A first branch path feeds clean lubricating water for lubricating a system of bearings within the system bearing section 6. The second branch path feeds clean water through a pressure regulator in the steam generator input section 3 and via other distribution pipes to an input manifold of the steam generator in section 4. Accordingly, the high pressure steam is generated and delivered to the steam turbine located within turbine section 5.
The function of the turbine located at section 5 and supported on bearings located within bearing section 6 is to drive a hot water pump located at section 7. Hot, high pressure water is thus impelled upward by the rotating pump blades 26 between the rotating conical end 23 of the pump and an associated stationary shroud 25; the hot water is pumped upward at high velocity in the annular conduit between pipes 9 and 10, thus permitting use of the thermal energy it contains at the earth's surface. More important, the hot water is pumped upward to the earth's surface 11 at a pressure preventing it from flashing into steam and thus undesirably depositing dissolved salts at the point of flashing.
Accordingly, it is seen that the extremely hot, high-pressure well water is pumped upward, flowing in the annular region defined by alloy pipes 9 and 10. Heat supplied by the hot well water readily converts the clean water flowing into the steam generator section 4 into highly energetic, dry, super-heated steam. The clean water, before flowing into the pressure regulator system of input section 3, is at a very high pressure due to its hydrostatic head and also because of the action of the surface-located pressure pump 37 so that it may not flash into steam. The pressure regulator system at location 3 controls the pressure of the clean water flowing therethrough so that it may be vaporized and superheated in the steam generator in section 4. The highly energetic steam drives the steam turbine at section 4 and is then redirected to flow upward to the surface 11 after expansion as relatively cool steam flowing within the annular conduit defined between alloy pipes 8 and 9. Thermal energy is recovered, as will be discussed, at the earth's surface 11 primarily from the hot, high pressure water flowing upward between pipes 9 and 10, but may also be retrieved at the earth's surface 11 from the turbine exhaust steam, if desired.
As described in the aforementioned Matthews patent, the hot, high pressure water within well casing 10 is fed by pipe 10a to a conventional surface thermal power plant 30 which may include in the usual manner a vapor generator system in which a major part of the energy in the hot geothermal fluid is converted into energy in high pressure vapor for driving an alternator supplying electrical energy on power lines 24, 24. The cooled geothermal fluid is pumped by pump 31 back deep into the earth via re-injection well 32. Thus, the geothermal fluid flow loop is effectively completed and fluid and dissolved mineral salts are returned into deep strata of the earth.
Still referring to FIG. 1, a representative closed loop for supplying and re-injecting clean water into the deep well geothermal system will be described. The steam exhausted upwardly from the driving turbine at section 5 of that well is conveyed by pipes 9 and 9a to a heat exchanger element 39 of a conventional heat exchanger 38 and, after condensation therein, flows through the normally operating pressure pump 37. Heat exchanger 38 may be operated by supplying cooling water in a third loop including a conventional cooling tower (not shown) to pipe 34 connected through heat exchanger element 40 and output pipe 35 back to the same fluid cooling tower. Alternatively, known expedients may be employed for extraction of additional energy during the condensation process for use by power plant 30.
The clean water condensate is pumped by the conventional pump 37 for re-injection into the deep well pipe 8 at a pressure substantially above that of the pumped hot well water. Replenishment water may be supplied from the normally inactive source 33.
As previously noted, the steam turbine driven-hot water pump system is to be suspended at the bottom of the well primarily from the turbine exhaust steam pipe 9. The suspended apparatus includes sections 3 through 7 of the geothermal pump system. After the assembly of sections 3 through 7, the geothermal pump system is lowered into the well casing pipe 10 to its operating level by the gradual lowering of the steam exhaust pipe 9 as the latter is assembled. The clean water injection pipe 8 may be similarly introduced as the assembly is lowered and therefore also lowered into its operating position with the geothermal pump system. Alternatively, the geothermal pump system and steam exhaust pipe 9 may be fed into the well first to its operating location. Then, the clean water injection pipe 8 may be fed into the steam exhaust pipe 9 and, using conventional oil well technology, may then be stabbed into a previously supplied seating nipple (not shown) of standard design furnished at the top of the steam generator input section 3. The weight of the water injection conduit 8 is intended to be borne largely by the top of section 3 and is therefore also supported as a tension load by the steam exhaust pipe 9.
Before the geothermal pump system is put into its operating position, an annular packer element must be provided at that position and an annular seal element must be added to the hot water pump section 7 of the apparatus. While the annular packer 46 of FIG. 2 is permanently affixed during operation of the well to the inner wall of well casing pipe 10, the cooperating pump seal element 45 may translate axially with respect to packer 46 and pipe 10 because of the effects of thermal expansion. The geothermal pump system, hanging as it does from the long steam exhaust pipe 9, may move up or down by inches, so that a slippable seal interface 47 is required between pump section 7 and the well pipe casing 10. The inner wall of casing pipe 10 will normally be rough and will vary substantially in diameter and roundness so that it is not possible for the inner wall to provide a proper sealing surface to slide against in the prevailing pressure and temperature situation.
With reference to the pump seal element 45, it includes a hollow circular expanding section 48 that is simply a smoothly contoured extension of the fixed annular pump shroud 25, the latter being supported from pump section 7 by a plurality of radial vanes 27. The tapered section 48 ends in a hollow circular cylindric section 49 with a thickened end annulus 50. The tubular seal element 45 is thus contoured to encourage smooth flow of the hot well water between the pump shroud 25 and nose cone 23 for accelerated upward flow around pump section 7 in the channel bounded by pipe 10. The annulus 50 includes an annular groove 52 within which is placed a high temperature sealing ring 51 for supplying the required seal interface 47. The seal ring 51 may be composed of a commercially available elastomer designed for operating above 400° Fahrenheit, a combination of an elastomer and asbestos fibers, or the like. Metal parts of the device are made of corrosion resistant alloy.
The packer system 46 of FIG. 2 is a modification of a packer such as is conventionally used in oil well operation. These devices are conventionally defined as devices for packing or filling the space between the wall of a well or well casing and the active well pipe or between two pipe strings in a well when the pipe strings in the well may include adjoining pipes of different sizes. In FIG. 2, the internally threaded ring portion 62 without elements 60 and 61, the main ring 63, the toothed sector 64, the inclined plane ring 65, the seal 66, the inclined plane ring 67, the toothed sector 68, and the internally threaded ring 69 are conventional parts of a commercially obtainable packer. In the usual situation, the packer is lowered into the well by conventional well tools forming no part of the present invention and which are removed from the well after the installation is done.
During installation, the main ring 63 is held stationary by the tool while the internally threaded rings 62 and 69 are rotated in such a sense that they move toward each other on the respective threaded portions 63a, 63b. The toothed sectors at 64 and 68 are driven radially outward as well as toward each other, so that the teeth of the sectors bite into the inner wall of well casing pipe 10 because of the cooperative action of the inclined plane rings 65 and 67, thus fixing the location of packer 46. The latter rings bear against the seal shoes 66a and 66b, compressing the seal element 66 against the inner wall of pipe 10, thus forming an effective seal against fluid flow. While a representative packer has been described, it will be evident that other types of commercially available seals and packers may be employed for the purposes of the invention. Again, the seal ring 66 may be made of various high temperature materials including elastomers, a combination of an elastomer with asbestos, or a combination of asbestos and a polymerized flurocarbon resin, for example. It will be evident that the apparatus may be removed from the well simply by reversing the assembly program.
According to the present invention, the conventional upper internally threaded ring 62 is modified by adding an upwardly extending tubular cylinder portion 60. The internal wall of cylinder 60 is smoothly finished and accurately round so as to provide an ideal mating seal interface 47 with the round ring seal 51. The cylinder 60 is extended upward to a thickened annular portion with an internal taper 61. The taper permits the seal element 45 to mate readily with the cylinder 60 and packer 46 as the geothermal pump system is lowered into its final position. Like other parts of the packer 46, cylinder 60 and its end annulus forming taper 61 are composed of a corrosion resistant alloy such as stainless steel.
Accordingly, it is seen that the invention is a significant improvement over the prior art, facilitating the ready installation and reliable operation of geothermal systems; according to the invention, there are provided novel means for the support of a deep well geothermal pump system within the well casing pipe from the earth's surface by the pump-driving turbine exhaust steam conduit. In view of the differential expansion effects on the relative lengths of the casing pipe extending downward from the earth's surface and the exhaust steam conduit contained therein, a novel flexible seal is provided between the suspended geothermal pump system and the well pipe casing. A first element of the improvement provides a vertical smooth cylindrical sealing surface at the desired location for the deep well apparatus by means itself fully sealed to the well casing pipe. A second element assures easy assembly of a second seal interfacing the cylindrical sealing surface and suspended from the hot water pump so as to permit sliding motion of the seal in the hostile prevailing environment, yet affording reliable and long-life sealing action.
While the invention has been described in its preferred embodiments, it is to be understood that the words which have been used are words of description rather than of limitation and that changes within the purview of the appended claims may be made without departure from the true scope and spirit of the invention in its broader aspects.
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A geothermal energy transfer and utilization system makes use of thermal energy stored in hot solute-bearing well water to generate super-heated steam from an injected flow of clean water. The super-heated steam is then used for operating a turbine-driven pump at the well bottom for pumping the hot solute-bearing water at high pressure and in liquid state to the earth's surface, where it is used by transfer of its heat to a closed-loop steam generator-turbine-alternator combination for the beneficial generation of electrical or other power. Residual concentrated solute-bearing water is pumped back into the earth. The clean cooled water regenerated at the surface-located system is returned to the deep well pumping system also for lubrication of a fluid bearing arrangement supporting the turbine-driven pump system. The deep well pump system is supported within the well casing pipe from the earth's surface by the turbine exhaust steam conduit. In view of differential expansion effects on the relative lengths of the casing pipe and the exhaust steam conduit, a novel flexible seal is provided between the suspended turbine-pump system and the well pipe casing.
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BACKGROUND
The present invention relates generally to the manipulation of genetic materials and more particularly to the use of recombinant procedures to selectively modify double-stranded DNA sequences, especially cDNA sequences, for storage and incorporation into expression vectors.
The development of specific DNA sequences for insertion into DNA vectors in an attempt to secure microbial expression of polypeptides encoded thereby is accomplished by a variety of techniques. Three principal methods for obtaining DNA sequences are: (1) the chemical manufacture of DNA sequences; (2) the isolation of double-stranded DNA sequences from donor DNA; and (3) the in vitro synthesis of double-stranded DNA sequences by reverse transcription of messenger RNA isolated from donor cells. The latter methods involve formation of a DNA complement of messenger RNA and are referred to as "cDNA" or "copy DNA" methods.
Chemical manufacture of polypeptide-specifying DNA sequences is clearly a method of choice, provided the amino acid sequence of the polypeptide to be microbially expressed is known and efficient synthetic procedures can be applied in the assembly of the sequence. (See, e.g., Stabinsky, U.S. patent application Ser. No. 375,493, filed May 6, 1982; and Alton, et al., U.S. patent application Ser. No. 375,494, filed May 6, 1982).
When double-stranded DNA sequences are chemically manufactured, it is seldom the case that significant difficulties are encountered either in storing the manufactured sequences in a convenient vector (such as the E.coli DNA plasmid, pBR322) or in inserting the sequences into functional expression vectors wherein their microbial transcription into mRNA is placed under the control of selected promoter/regulator sequences, transcription termination sequences, and the like. This is so because designs for chemical manufacture of polypeptide synthesis-directing DNA sequences can rather easily be adapted to incorporate initial and terminal sequences specifying, e.g., microbial mRNA translation initiation sequences, microbial mRNA translation termination sequences, and DNA sequences providing recognition sites for restriction endonuclease enzyme cleavage which will facilitate storage and/or insertion of the sequence into selected expression vectors.
Where the sequence of the polypeptide to be expressed is unknown, and in cases when chemical manufacturing procedures are not efficiently practiceable, resort must be made to donor DNA isolation and cDNA procedures to obtain desired DNA sequences. Such sequences are seldom in condition for ready incorporation into microbial expression vectors. It is almost invariably the case that the isolated sequence must be processed at its 5' end either to delete base pairs coding for an undesired polypeptide leader region or to insert base pairs coding for microbial translation initiation. Similarly, where the isolated sequence includes at its 3' end base pairs coding for an undesired terminal polypeptide region, these must ordinarily be deleted and an appropriate translation termination sequence must be inserted. Further, it is almost invariably the case that DNA sequences will need to be added to the isolated sequence to allow the storage (and amplification) in a vector or the insertion of the isolated sequence into an expression vector in the correct reading frame and location relative to a promoter/regulator region and/or transcription termination sequence.
A number of procedures have been developed in the art for performing selective modifications on double-stranded sequences. U.S. Pat. No. 4,342,832, for example, describes construction of cloning vehicles wherein a cDNA gene coding for a desired polypeptide is placed under the control of a selected expression promoter. Briefly stated, the cDNA sequence is analyzed for the presence of a unique restriction endonuclease recognition site near the 5' end and cleaved at such a site, effectively deleting undesired sequences (5' to the structural gene) along with at least a part of the desired polypeptide coding region. A chemically manufactured DNA sequence is then employed as a replacement for the lost polypeptide coding region and this manufactured sequence will ordinarily include a translation initiating sequence and desired recognition sites to facilitate incorporation into an expression vector. The same types of manipulations can be performed to secure modification of the 3' end of the cDNA sequence.
In the absence of one or more unique recognition sites in the DNA sequence to be modified, of course, the procedures of U.S. Pat. No. 4,342,832 cannot be performed. Further, even where such recognition sites are available, practice of the methods may require chemical synthesis of very long double-stranded DNA sequences as replacements for deleted polypeptide coding sequences and may therefore involve nearly as much work as total gene synthesis.
Of interest to the background of the invention are those publications treating the use of single-stranded DNA "primers" for isolating selected cDNA sequences and for effecting nucleotide base changes in central and terminal portions of double-stranded DNA sequences. See, e.g., Montell, C., et al., Nature, 295: 380-384 (1982): Gillam, S., et al., Gene, 12: 129-137 (1980); Goeddel, D., Nucleic Acids Research, 8: 4057-4074 (1980); and Hu, N., et al., Gene, 17: 271-277 (1982).
Of particular interest to the background of the invention are recently-published European Patent Application Nos. 054330 and 054331, which illustrate use of primers in methods for modifying double-stranded cDNA sequences. According to the illustrated methods, the DNA sequence coding for "mature" thaumatin is isolated from the central portion of a larger sequence coding for preprothaumatin by a series of manipulations involving use of single-stranded primers. The single-stranded primers are hybridized to single-stranded portions of the mature thaumatin sequence which have been isolated from the preprothaumatin double-stranded sequence by, e.g., denaturation. DNA polymerase and S1 endonuclease digestion are employed to provide a sequence having, at its 5' end, codons specifying the initial amino acids of mature thaumatin and, at its 3' end, a translation termination codon ##STR1## In order to incorporate such a modified sequence into an expression vector, it must be immediately associated by blunt-end ligation with one or more synthetic, double-stranded, "linker" DNA sequences providing a translation initiation codon and/or a recognition site suited for proper insertion into the expression vector. (See, FIG. 4 of 054330 and FIG. 13 of 054331). Significant disadvantages attend use of the procedures illustrated. First, no means is provided for developing a selected terminal double-stranded sequence apart from performing a separate reaction with a linker. Second, no means is provided for "storage" or amplification of the modified double-stranded DNA sequence. Each modifying procedure must therefore be followed at its completion by association with a synthetic linker. If insertion into two different expression vectors is desired, for example, the modification procedures must essentially be duplicated in their entirety.
That the above-noted examples of procedures for selective modification of double-stranded DNA sequences are not readily and easily applied is evidenced by the fact that numerous cDNAs coding for commercially important polypeptides have been isolated and sequenced but have not as yet been successfully employed to effect microbial expression of the polypeptides. As one example, Sasavage, et al., J. Biol.Chem., 257: 678-681 (1982) reports on the preparation, isolation, and sequencing of a double-stranded DNA coding for the 199 amino acid polypeptide sequence of bovine prolactin along with an approximately 30 amino acid untranslated leader region. However, the authors did not report microbial expression of bovine prolactin.
There exists, therefore, a substantial need in the art for improved methods and materials for selective modification of double-stranded DNA sequences, especially cDNAs, allowing for their storage and their incorporation into expression vectors. Such methods could be illustratively applied to readily secure the microbial expression of commercially significant polypeptides such as bovine prolactin.
BRIEF SUMMARY
The present invention provides novel, multi-step methods for selective modification of double-stranded DNA sequences facilitating their storage and incorporation into expression vectors. Briefly put, manufactured single-stranded or partially double-stranded DNA "primers" are hybridized to complementary regions of single-stranded forms of DNA sequences to be altered. Desired, selectively modified double-stranded DNA sequences are then formed by DNA polymerization and nuclease digestion of undesired double- and single-stranded regions.
Where the modification desired is simply the provision of one or two blunt ends facilitative of insertion into a storage vector, only a single-stranded primer need be used. Where it is desired to incorporate a transcription initiation or termination codon and/or where one or two entire restriction enzyme recognition sites are to be provided which will facilitate insertion into, e.g., an expression vector, the present invention dictates use of a partially double-stranded primer.
Procedures of the invention for modifying a double-stranded DNA sequence using a single-stranded primer include the following initial steps:
(1) forming a first selected single-stranded DNA copy of the double-stranded DNA sequence;
(2) hybridizing the first selected single-stranded copy to a manufactured single-stranded DNA sequence which is (a) complementary to a selected portion of the first selected single-stranded copy; and (b) has as the initial bases of its 5' end bases which, when complemented, form half of a recognition site for cleavage by a blunt-end-forming restriction endonuclease; and,
(3) incubating the hybridized product of step (2) with nucleotide triphosphates and DNA polymerase under conditions facilitative of 3' extension of the manufactured sequence with bases complementary to the first selected single-stranded DNA copy, whereby the original double-stranded DNA sequence is reconstructed except for its sequence 3' to the site of hybridization of the selected single-stranded copy to the 5' end of the manufactured sequence.
If it is desired to isolate double-stranded DNA with half a blunt-end restriction enzyme recognition site at one of its ends, the following two additional steps are performed on the product of step (3):
(4) treating the product of step (3) to delete remaining single-stranded sequences 3' to the site of hybridization of the selected single-stranded copy to the 5' end of the manufactured sequence; and,
(5) recovering the desired selectively modified double-stranded DNA sequence.
If it is desired to modify the double-stranded DNA so that it has halves of blunt-end recognition sites at each of its ends, the following additional steps are performed:
(6) forming a second selected single-stranded DNA copy of the modified double-stranded DNA sequence of step (5), the second selected single-stranded copy being the partial complement of the first selected single-stranded copy of step (1); and,
(7) repeating steps (2), (3), (4), and (5) on the second selected single-stranded copy of step (6).
In the above procedures the 5' end of the manufactured single-stranded DNA sequence preferably contains bases which, when complemented, provide a half of a recognition site for a restriction endonuclease enzyme such as PvuII, HpaI, BalI, SmaI, HaeIII, AluI, NaeI or StuI, which are likely to correspond to unique restriction enzyme recognition sites in common DNA vectors such as pBR322. The manufactured single-stranded DNA sequence is desirably in the range of from about ten to about twenty bases in length and preferably about twelve.
Procedures of the invention for modifying a double-stranded sequence using a partially double-stranded primer include the following five initial steps:
(1) forming a first selected single-stranded DNA copy of the double-stranded DNA sequence;
(2) hybridizing the first selected single-stranded copy to a manufactured DNA sequence which comprises (a) a single-stranded portion complementary to a selected portion of the first selected single-stranded copy; and, (b) a double-stranded portion having a free end and an end wherein one strand is joined to the single-stranded region, which double-stranded portion includes base pairs forming a recognition site for cleavage by a restriction endonuclease enzyme and/or includes at its free end base pairs forming half of a recognition site for cleavage by a blunt-end-forming restriction endonuclease;
(3) incubating the hybridized product of step (2) with nucleotide bases and DNA polymerase under conditions facilitative of 5' to 3' extension of the single-stranded portion of the manufactured sequence with bases complementary to the first selected single-stranded DNA copy, whereby the original double-stranded DNA sequence is reconstructed except for its sequence 3' to the site of hybridization of the selected single-stranded copy to the 5' end of the single-stranded portion of said manufactured sequence;
(4) treating the product of step (3) to delete single-stranded sequences 3' to the site of hybridization of the selected single-stranded copy to the 5' end of the single-stranded portion of the manufactured sequence; and,
(5) recovering the desired selectively modified double-stranded DNA sequence.
If the original double-stranded DNA is to have similar modifications at both ends, the following additional steps are performed:
(6) forming a second selected single-stranded DNA copy of the modified double-stranded DNA sequence of step (5), the second selected single-stranded DNA copy being the partial complement of the first selected single-stranded copy of step (1); and,
(7) repeating steps (2), (3), (4), and (5) on the second selected single-stranded copy of step (6).
Where the 5' end of a double-stranded sequence is to be modified, the double-stranded portion of the manufactured DNA primer sequence may also include a ##STR2## transcription initiation codon. Where the 3' end of a double-stranded sequence is to be modified, the double-stranded portion of the primer may also include ##STR3## or similar transcription termination codon. Where the double-stranded portion of the primer includes base pairs providing an entire recognition site for restriction endonuclease cleavage, the site is generally one which corresponds to a unique recognition site present in a projected expression vector. When the double-stranded portion is to include at its free end base pairs forming half a blunt-end restriction enzyme recognition site (for insertion of the modified sequence into a storage vector), it is preferred that they be those associated with PvuII, HpaI, BalI, SmaI, HaeIII, AluI, NaeI, or StuI.
The length of the manufactured partially double-stranded primer may range from about ten to about twenty bases in its single-stranded region and from about ten to about twenty base pairs in its double-stranded region.
Use of filamentous bacteriophages such as M13 or the like substantially facilitates practice of procedures of the invention irrespective of whether single-stranded or partially double-stranded primers are employed. Further, it is within the comprehension to employ single-stranded priming procedures to effect a modification at one end of a double-stranded DNA sequence and partially double-stranded priming procedures to effect modification of the other end.
A further aspect of the present invention is the provision of a DNA sequence comprising base pairs arranged in codons specifying the amino acid sequence of bovine prolactin, wherein the initial base pairs of the protein coding sequence are ##STR4## The DNA sequence may also include a ##STR5## codon, for transcription initiation.
Yet a further aspect of the present invention is provision of microbial expression vectors comprising a DNA sequence coding for bovine prolactin and microbial cells stably transformed with such vectors.
Cultivation of transformed microorganisms results in microbially expressed polypeptides having the biochemical properties of bovine prolactin.
Further aspects and advantages of the present invention will be apparent upon consideration of the following detailed description of the practice of preferred embodiments thereof, wherein
FIGS. 1 and 2 are schematic diagrams illustrating the various modifications to double-stranded DNA by the manipulations of the method of the present invention; and
FIGS. 3 and 4 illustrate manipulations according to the invention involved in construction of expression vector cGH T21 harbored in ATCC No. 39182.
DETAILED DESCRIPTION
The methods of the present invention can be best understood through reference to schematic FIGS. 1 and 2. For ease of illustration, each number and letter in the schematic sequences in each figure represents three bases. FIGS. 1 and 2 illustrate manipulations performed on a hypothetically donor-isolated or cDNA-derived double-stranded DNA sequence: ##STR6## wherein A' is the complement of A, B' is the complement of B, and so on.
By virtue of its having been isolated from donor DNA or produced by cDNA methods, the sequence to be modified will typically include recognition sites RS 1 and RS 2 for cleavage by blunt- or sticky-end-forming restriction endonuclease enzymes RE 1 and RE 2 at ##STR7## respectively.
An initial step in the procedures of the invention is the formation of a selected single-stranded copy of the double-stranded DNA sequence to be modified. Because DNA polymerases utilized in further steps of the method will only permit primer extension in the 5' to 3' direction, if it is desired to modify the 5' end of the gene, the single-stranded copy selected must be the "minus", "non-coding" strand. If modification is desired for the 3' end of the gene, the single-stranded copy selected must be the "plus" or "coding" strand. Selection of the "plus" or "minus" single strand from the two single strands of opposite orientation forming the double-stranded DNA can be accomplished in several ways:
(a) In FIG. 1 of the single-stranded DNA copy is accomplished by use of filamentous single-stranded DNA M13 bacteriophages (which are shown in FIG. 1 in the double-stranded replicating form (RF DNA)). The single-stranded phage DNA of M13 is always the plus strand. However, either the plus or minus strand of a double-stranded insert DNA can be cloned by use of M13 vectors, mp8 and mp9. A poly linker which contains multiple recognition sites for cleavage by restriction endonuclease enzymes (e.g., RE 1 and RE 2 ) for cloning foreign DNA fragments into M13 can be introduced into the bacteriophage DNA in one orientation in mp8 and the opposite orientation in mp9. (Messing, J. and Vreira, J., Gene, 19, 269-276 (1982)). The double-stranded DNA sequence is easily inserted into either the mp8 or mp9 bacteriophage (previously cleaved with RE 1 , RE 2 ) at the corresponding recognition sites by a ligase enzyme.
(b) In FIG. 2, the initial step of forming a selected single-stranded copy of the double-stranded DNA sequence is accomplished by denaturation of the double-stranded sequence. The denaturation (other than through use of bacteriophages) can occur through use of heat, chemical or mechanical treatment of the double strand, thereby creating a "pool" of both minus and plus single strands. See Goeddel, et al., Nucleic Acids Research, 8: 4057-4074 (1980). Isolation of the selected "plus" or "minus" single strand for treatment with the further steps of the method occurs upon addition of the manufactured primer sequence of step 2, which is composed of bases complementary to a strand of one orientation only. The strand without a complementary primer remains unhybridized and is thus not "selected".
In the second step of procedures involving single-stranded manufactured primers, the selected single-stranded copy, e.g., 5'-ABCDEF -UVWXYZ-3' (hereafter "plus" strand), is hybridized to a manufactured single-stranded DNA sequence, e.g., Primer A, represented by 3'-U'V'W'X'-5'. Primer A is complementary to a selected portion of the "plus" strand, 5'-UVXY-3', thereby forming the hybrid ##STR8##
Alternatively, the selected single-stranded copy 3'-A'B'C'D'E'F'--U'V'W'X'Y'Z'-5' (hereafter "minus" strand) would be hybridized to manufactured Primer C, represented by 5'-CDEF-3', forming the hybrid ##STR9## Manufactured Primers A and C, and any single-stranded primer used in the method, are each desirably in the range of from about ten to about twenty bases in length. Primers A and C represent the preferred length of twelve bases. Manufactured primer sequences of less than ten bases generally tend to form unstable hybrids, which may dissociate at the room temperature required for subsequent primer extension. Manufactured primer sequences of more than twenty bases, while able to form hybrids with good stability, require time-consuming manufacturing processes, and may therefore be less practical for use in the method of the present invention.
Before the primer sequence is manufactured, the selected single-stranded copy is scanned for the presence of a naturally-occurring sequence of bases which, when complemented by a primer, can form half of a recognition site for cleavage by a blunt-end forming restriction endonuclease. The location of such a sequence on the single-stranded copy determines the point of hybridization of the manufactured primer.
Therefore, as the initial bases of one end of the primer used (X' for Primer A and C for Primer C) there are bases which, when complemented, form half of a selected recognition site (1/2RS 3 , 1/2RS 5 ) for respective blunt end-forming cleavage by endonucleases RE 3 and RE 5 . The number of initial bases coding for half of a recognition site on the manufactured primer sequence can vary depending upon the particular restriction endonuclease to be utilized in cleavage. For example, the recognition site for PvuII cleavage is formed of six base pairs, ##STR10## If the selected recognition site was identified for cleavage by PvuII, three initial bases on the primer single strand, when complemented, would code for half of the site necessary for blunt end-forming cleavage. For example, Primer A's 5' initial bases (X') would, upon hybridization, form the 3' half of the recognition site for PvuII, or 5'-C T G-3'. Primer C in FIG. 1 could have as its 5' initial bases (C) 5'-CTG-3' which, when complemented, would also form the 3' half of the recognition site for PvuII. Other recognition sites exist which are formed of four base pairs. However, four base pair recognition sites oocur quite frequently in most conveniently employed plasmid DNA vectors and thus are of limited practical interest for the purposes of the present invention.
In the third step of the method, the hybrid Primer A-"plus" strand or hybrid Primer C-"minus" strand is incubated with deoxynucleotide base triphosphates (dBaseTP's) and DNA polymerase I (Klenow fragment). This incubation at room temperature for a specified period of time facilitates 5' to 3' extension of Primer A with bases complementary to the bases of the "plus" strand or 5' to 3' extension of Primer C with bases complementary to the bases of the "minus" strand.
The hybrid strands may be extended to any desired region along the length of the single-stranded copy to form a continuous double strand, with the length of the resulting double-stranded region depending upon the amount of time primer extension is allowed to continue.
When Primer A is employed, the original doublestranded DNA sequence is reconstructed, ##STR11## except for the single-stranded sequence (Y'Z') 3' to the site of hybridization of the "plus" strand with the 5' end of manufactured Primer A. Similarly, when Primer C is employed, the original double-stranded sequence is reconstructed as: ##STR12##
A fourth step in the method is treatment of the reconstructed double-stranded DNA sequence with an enzyme capable of digestion of single-stranded DNA sequences, such as S1 nuclease. The addition of S1 nuclease removes remaining single-stranded regions (XY or A'B'). Thus, after cleavage at the unmodified end with RE 1 or RE 2 , a double-stranded DNA sequence is recovered which contains deletion modifications to its 3' or 5' end including half of a new recognition site (1/2RS 3 or 1/2RS 5 ) responsive to cleavage by endonuclease (RE 3 or RE 5 ). These modifications enable easy insertion of the 3' or 5' modified end of the gene into the complementary half of the recognition site in an expression vector for storage and amplification.
In addition to modifying one end of the double-stranded sequence, the methods of the present invention involving single-stranded primers also provide for modification of both ends. For example, after Primer A has been used to achieve the 3' modification of the original double-stranded sequence to ##STR13## the modified double-stranded sequence can be inserted back into a bacteriophage RF DNA (cleaved with RE 1 and RE 3 ), and the "minus" modified strand isolated therefrom. The modified minus strand could then be subjected to the same steps of the method using Primer C. Alternatively, where no complementary recognition sites exist in an available bacteriophage or other replicating vector, the modified double-stranded sequence can be denatured to separate the modified plus strand from the modified minus strand (FIG. 2). Use of Primer C to hybridize with the minus strand in the pool of plus and minus strands will enable primer extension of only the minus strand when in the presence of dBaseTP's and DNA polymerase. Subsequent treatment of the reconstructed double-stranded sequence with S1 nuclease will digest not only the remaining single-stranded regions on the reconstructed double-stranded sequence but also the single plus strands in the pool.
Practice of the method, therefore, also allows recovery of a double-stranded DNA sequence which contains modifications to both of its ends introduced by the manufactured single strand Primers A and C. The modification of both ends of the sequence to incorporate half of a restriction endonuclease recognition site on each end allows ready insertion of the modified DNA sequence into a vector with complementary recognition sites for storage and amplification.
Where selective modification of a double-stranded DNA sequence involves utilizing a manufactured partially duplexed primer, the selected single-stranded copy of the double-stranded DNA sequence is formed by the same procedures described above for use of the manufactured single-stranded primers, i.e., use of a single-stranded DNA bacteriophage (FIG. 1) or by denaturation (FIG. 2). The selected single-stranded sequence (e.g., the "minus" strand) isolated from M13mp8 or the denaturation pool is hybridized to manufactured DNA Primer D which includes (1) a single-stranded portion (5'-CDEF 3') complementary to a portion (3'-C'D'E'F'-5') of the selected minus single-stranded sequence and (2) a selected double-stranded portion ##STR14## having a free end at ##STR15## and an opposing end, wherein strand 5'1234- is joined to the single-stranded portion 5'-CDEF 3'. The double-stranded portion of Primer D either includes base pairs ##STR16## forming a complete recognition site (RS 6 ) for cleavage by a restriction endonuclease enzyme (RE 6 ) and/or includes at ##STR17## half of a recognition site 1/2RS 8 for cleavage by a blunt end-forming RE 8 .
In a like manner, a selected plus strand can be hybridized to Primer B including double-stranded portion ##STR18## providing the entire RS 4 restriction endonuclease recognition site for cleavage by RE 4 endonuclease and/or half a site 1/2RS 7 for blunt-end cleavage by RE 7 .
The Primer D/minus strand hybrid or Primer B/plus strand hybrid sequence is incubated with deoxynucleotide base triphosphates and DNA polymerase, under conditions facilitative of 5' to 3' extension of the hybridized single-stranded portion. As in the previously-described methods, the extension length depends on the amount of time the reaction continues. In use of Primer D, this third step allows reconstruction of the double-stranded sequence except for ##STR19## because this region is 3' (on the minus strand) to the site of hybridization at ##STR20## When Primer B is used, the original sequence is reconstructed except for ##STR21## Further treatment of the reconstructed double-stranded DNA sequence with S1 nuclease deletes 3'-A'B'-5' or 5'-YZ-3' and any remaining single-stranded regions (i.e., the plus strand in the denaturation pool or single-stranded phage DNA). The reconstructed sequence is treated with S1 nuclease. RE 1 or RE 2 treatment yields either modified double-stranded DNA sequence, ##STR22## The nick between bases 4' of Primer D and the adjacent bases C' of the minus strand or bases 6 of Primer B and adjacent bases X of the plus strand is repaired (e.g., when the modified double-stranded sequence is ligated into a bacterial vector by the action of an enzyme, such as T 4 ligase).
In a process analogous to that described for the single-stranded Primers A and C, the method for selective modification of a double-stranded DNA sequence by partially double-stranded primers can be varied to include modification of both ends of the double-stranded sequence. For example, the plus strand of the modified double-stranded sequence would be isolated, by M13mp9 or denaturation. Primer B in FIGS. 1 and 2 would be utilized in the steps of the method described above for modification of the 5' end, resulting in a double-stranded sequence modified at both ends, i.e., ##STR23##
Another advantage for use of double-stranded primer sequence like Primers D and B is that the primers enable the insertion of a methionine coding region 5' to the DNA sequence coding for a desired polypeptide (e.g., at position 4) to allow translation of the sequence and/or a stop codon 3' to the DNA coding region (e.g., at position 6) to terminate translation when the modified double-stranded sequence is in an expression vector.
An example of use of the method of the present invention is the creation of an expression vector including a modified cDNA sequence which codes for the microbial synthesis of bovine prolactin hormone. The following Examples 1 through 4 demonstrate manipulations performed on a double-stranded DNA sequence containing the sequence coding for bovine prolactin hormone (bPRL) polypeptide:
(1) identification and isolation of cloned bPRL DNA sequences in pBR322-SV40 recombinants by use of a rat prolactin cDNA probe;
(2) formation and sequencing of single-stranded copies of bPRL sequences by use of phage M13;
(3) manufacture of a single-stranded primer sequence and its use in hybridization with the selected single-stranded sequence and primer extension to form a 5' modified sequence; and
(4) further modification of the sequence of Example 3 for construction of a bacterial cell expression vector.
Example 5 relates to biochemical similarity of microbially-produced bPRL according to the invention and bovine prolactin purified from bovine pituitary glands. Example 6 describes a sequential competition radioimmunoassay employing the bovine prolactin polypeptide produced in cells transformed with plasmids harboring bPRL.
Another example of use of the method of the present invention are the manipulations performed on the DNA sequence coding for expression of growth hormone of the chicken species disclosed in applicant's co-pending patent application Ser. No. 418,846, filed Sept. 16, 1982. In that application, a high molecular weight polypeptide having the biochemical and immunological properties of growth hormone native to avians is disclosed. The construction of an illustrative bacterial cell expression vector cGH-T21 harbored in ATCC No. 39182 was the result of the manipulations of the present invention. Those manipulations are the subject of Examples 7 and 8 and FIGS. 3 and 4 following.
EXAMPLE 1
The nucleotide and predicted amino acid sequences of a cDNA coding for bovine prolactin was deduced by Sasavage, et al., supra. The described sequence is as follows: ##STR24##
To obtain the cDNA sequence coding for bovine prolactin, complementary DNA made from bovine pituitary mRNA was cloned into pBR322-SV40 vectors by the method of Okayama, H., and P. Berg, Mol.Cell.Biol., 2: 161-170 (1982). These recombinants were screened for the presence of bPRL sequences using a rat prolactin cDNA probe. The rat probe aligned with the homologous bovine prolactin sequences in the clones, thus enabling ready isolation of those clones containing bPRL. The clone containing the largest insert (bPRL8) of the eight found to hybridize to rat prolactin (rPRL) was chosen for further manipulations.
EXAMPLE 2
Insert bPRL8 was sequenced by the dideoxy method using M13-bPRL8 clones as templates. The sequence of bPRL8 revealed the following structural components of the gene:
(1) a 5' untranslated sequence of 50 bases,
(2) a 30 amino acid leader,
(3) a 199 amino acid mature protein, and
(4) a 3' untranslated sequence of 146 bases.
These findings are all consistent with those published by Sasavage, N. L., et al., J.Biol.Chem., 257: 678-681 (1982), except for a few minor third base substitutions at amino acid numbers 67 and 76, and the absence of one C in the 3' untranslated region.
Specifically, the codon for amino acid number 67 (proline) was CCT, rather than CCG, as published; and for amino acid number 76 (histidine) CAC, rather than CAT. The C omitted is marked with an asterisk above it in the sequence above.
The entire bPRL sequence was not readily accessible for securing direct and optimal expression of bPRL in a microbial host due to the presence of the approximately 140 base sequence 5' to the bPRL coding region (which sequence presumptively codes for a 30 amino acid leader region) and a 5' untranslated region. In addition to deleting the 140 base sequence 5' to the first codon of the mature form of bPRL, to secure expression of bPRL the coding region should be provided with an initial ##STR25## and inserted into a transformation vector at a site under control of a suitable promoter/regulator DNA sequence. Due to the presence of a recognition site for cleavage by the Sau3A endonuclease in the long 3' untranslated sequence, that sequence presents no obstacle to securing expression. The sequence can be partially deleted by treatment with Sau3A at the recognition site ##STR26##
EXAMPLE 3
A primer sequence was manufactured for use in primer extension of a single-stranded copy of the bPRL sequence. The primer is synthesized by the amino phosphine method [Beaucage and Caruthers, Tetrahedron Letters, 22: 1859-1962 (1981)], on a solid support [Matteucci and Caruthers, J.Am.Chem.Soc., 103: 3185-3191 (1981)], except that 3% trichloroacetic acid in nitromethane is used instead of zinc bromide for the detritylation step. The primer sequence was a synthetic fifteen base oligimer complementary to an M13mp8 clone containing the entire bPRL cDNA sequence. The primer begins at nucleotide position +9 with respect to the first amino acid of the mature protein and extends to nucleotide position +23. The primer therefore had the sequence:
5'-CTGT CCC AAT GGG CC-3'.
The selected M13 single-stranded DNA sequence for bPRL (1 μg) was hybridized to copies of this primer (a 5 molar excess) in H Buffer (6.6 mM Tris-HCl pH 7.5, 6.6 mM MgCl 2 , 6.6 mM NaCl, and 5.0 mM dithiothreitol) at 85°-100° C. and allowed to slow cool to room temperature. The hybrid product was then incubated in the presence of deoxynucleotide base triphosphates (final concentration 0.5 mM each) and 1 unit of Klenow (large fragment of DNA polymerase I). The final reaction volume was 25 μl and incubation was carried out at room temperature for 20-30 minutes. This incubation time period allowed the primer sequence to be extended past the bPRL insert (past a Sau3A cleavage site) and partially around the M13 portion of the single-stranded clone. The primer extension reaction was stopped by the addition of 1.5 μl of 2% sodium dodecylsulfate (SDS) and then 1/4 volume of 5× Buffer D (50 mM Tris pH 7.5, 250 mM NaCl, and 5 mM EDTA) was added. The reaction was then extracted with an equal volume of phenol:CHCl 3 (50:50), CHCl 3 , and finally precipitated with ethanol. The reconstructed double-stranded DNA sequence was thereafter treated with S1 nuclease which digested the remaining single-stranded portions of the original M13 template 3' to the site of hybridization, including the 5' untranslated region through the nucleotide position +8 and the remaining single-stranded 3' region. The S1 reaction contained 50 mM KAc (pH 4.5), 200 mM NaCl, 1 mM ZnSO 4 , 25-100 units SI and the primer elongated DNA in a 25 μl volume. The reaction was carried out at 15° C. for 30 minutes, then stopped and treated as described for the primer elongation reaction. The 5' end of the reconstructed double-stranded sequence now was initiated by three bases forming the 3' half of a recognition site for cleavage by PvuII. Further treatment with Sau3A endonuclease to cleave the now-duplexed untranslated 3' region at a Sau3A recognition site was accomplished by:
(1) resuspending DNA from the previous reaction in 21.5 μl H 2 O;
(2) adding 2.5 μl of 10× Sau3A buffer (67 mM Tris pH 7.5, 67 mM MgCl 2 , 500 mM NaCl and 67 mM mercaptoethanol); and
(3) adding 0.6 μl of Sau3A (3 units) and allowing digestion to occur for 1 hour at 37° C.
This modified double-stranded sequence was recovered from the reaction as described for the previous reactions. A 3-to-5 molar excess of the modified DNA was ligated to 50-100 ng of pBR322 vector previously digested with BamHI and PvuII and gel purified. The DNA was then transformed into E.coli strain HB101 and the resulting transformants tested by plasmid analysis for the appropriate Sau3A and PvuII cleavage sites. One clone, bPRL13-2, contained the appropriate insert and was selected for further manipulations.
EXAMPLE 4
Construction of a vector for the direct expression of the mature form of bPRL was accomplished by further modification of the sequence developed in Example 3. An 18 base linker was manufactured containing 8 bases required to build back the first three codons of the bPRL-specifying DNA sequence, an ATG initiation codon, and bases providing an XbaI restriction site, which would enable cloning into a tryptophan (Trp) promoter of a pBR322-derived vector. The sequence of the linker was the following: ##STR27## In this linker, the 8 bases coding for nucleotide positions +1 through +8 differed from the original, cDNA bPRL sequence at nucleotide positions +3 and +6. The purpose of the two changes from C to A was to include E.coli preference codons for the required amino acids. A 3 molar excess of both the 18 base linker and the modified bPRL gene were ligated into a pBR322 derived Trp promoter vector (Pint-γ-txB4). The colonies isolated after transformation of E.coli which contain the appropriate insert configuration are capable of directing the synthesis of the mature form of bPRL.
Expression of a polypeptide having the biochemical properties of bPRL in E.coli was monitored by polyacrylamide gel electrophoresis of radiolabelled maxicells (Example 5) and by radioimmunoassay of crude bacterial lysates (Example 6).
EXAMPLE 5
The molecular weight of the microbially-produced bPRL polypeptide of the invention was determined by SDS-Polyacrylamide Gel Electrophoresis (SDS-PAGE) of 35 S-methionine ( 35 S-met) labelled maxicells (CSR603) harboring plasmids carrying the bPRL gene. Briefly, the procedure involves growing 10 mls of CSR603 (bPRL) in K-media [Rupp, et al., J.Mol.Biol., 61: 25-44 (1971)] to a concentration of 2×10 8 cells/ml. Five mls of cells are then irradiated in a 60 mm petri dish on a shaker platform with a UV dose of 1-5 J/m 2 , and allowed to shake for one hour at 37° C., at which point cycloserine is added at 100 μg/ml. The cultures remain shaking for an additional 8-12 hours and cells are thereafter collected by centrifugation and washed twice with Herschey salts [Worcel, et al., J.Mol.Biol., 82: 91-105 (1974)]. Cells are resuspended in 2.5 mls of Herschey media and incubated at 37° C. with aeration for one hour. 1 ml of cells are then placed in a 50 ml polypropylene tube with 50 μCi of 35 S-met (New England Nuclear) and 10 μg of 3-indoleacrylic acid and then incubated for another hour at 37° C. Finally, cells are harvested, lysed and analysed by SDS-PAGE and autoradiography. This procedure had been designed so that nearly all the labelled 35 S-met is incorporated into plasmid encoded gene products. [Sancar, et al., J.Bacteriol., 137: 692 (1979)].
Two protein bands were detected after autoradiography of the gel. One protein, β-lactamase with a MW of 30,000, is present in all cultures resistant to ampicillin containing pBR322 derived plasmids. A second protein of approximately 24,000 MW is seen only in cultures containing the plasmids encoding the bPRL gene. The MW of the recombinant bPRL is similar to that found for the natural bovine prolactin purified from pituitary glands.
EXAMPLE 6
To determine the levels of bPRL expression, a sequential competition radioimmunoassay [Zettner, et al., Clin.Chem., 20: 5-14 (1979)] was generated.
Samples of microbially produced bPRL are prepared for use in the RIA as follows:
Cells of E. coli K-12 strain HB101 containing the bPRL expression plasmid are grown in M9 minimal salts supplemented with 0.4% glucose, 1 mM MgSO 4 , 0.1 mM CaCl 2 , 5 mg/ml casamino acids and 10 μg/ml thiamine in a 37° C. shaker to an O.D. (A 600 ) of 1. At this point, 15 mls of cells are treated with 3-indoleacrylic acid (final concentration 10 μg/ml) and allowed to continue to shake at 37° C. for 1 hour. 10 mls cells are then pelleted at approximately 4,000×g in a Beckman J-6 and resuspended in 0.5 ml of a Tris-sucrose-lysozyme buffer (Goeddel, et al., Nature, 281, 544-548 [1981]) containing, in addition, 0.05% sodium dodecyl sulfate and 1 mM phenylmethylsulfonylfluoride. The cells are then placed on ice for 30 minutes after which they are treated with 0.11 ml of a DNase buffer and 10 μg of DNase I (Worthington) as described in Goeddel, et al. The supernate is then spun at 12,000×g for 15 minutes in an Eppendorf microfuge and the supernate is decanted into a tube containing 25 μ1 of 10% Triton X-100.
Purified bPRL isolated from bovine pituitaries was labelled with 125 I for use as tracer in the RIA using a modification of the chloramine-T reaction procedure described by Hunter and Greenwood, Nature, 194: 495-496 (1962). Briefly, the procedure involves combining 10 μg of bPRL in 10 μl of 0.05M bicarbonate buffer, pH 9.2, 50 μg chloramine T, and 500 μCi of sodium 125 I (approximately 17 Ci/mg) (New England Nuclear) in 50 μl of 0.2M tris-HCl, pH 7.2, 0.002M EDTA, and incubating for 1 minute at room temperature. Sodium metabisulfite (500 μg) is added to terminate the reaction and the mixture is loaded onto a 28 ml Sephadex G75 column previously washed with 0.1M phosphate saline (pH 8.0), 2% BSA, and 0.1M phosphate saline (pH 8.0), 0.1% BSA. Four 25-drop fractions are collected from the column and then 45-60 ten drop fractions.
Selected fractions containing radiolabelled material are tested for immune precipitability using the procedure of Keshet, et al., Nucleic Acids Research, 9, pp. 19-30 (1981). In this procedure, 2.5×10 4 cpm of iodinated bPRL is incubated with 1×10 -4 to 2×10 -4 dilutions of rabbit anti-bPRL in 0.5M Tris HC1 (pH 8.9), 2.0% BSA, 0.1% Triton X-100, 0.1% SDS, for 2 hours at room temperature. Twenty microliters of 10% w/v formalin-fixed Staphylococcus aureus pre-washed with RIA buffer is then added and the mixture incubated for 20 minutes at room temperature. Immune precipitates are collected by centrifugation (12,000×g for 3 min.) and washed 3 times in RIA buffer before counting.
The most immune-precipitable column fractions are then used to construct a serum dilution curve using the same procedure as above, but employing serum dilutions over the range of 1×10 -3 to 1×10 -6 . The serum dilution giving half maximal precipitation of 2.5×10 4 cpm of labelled bPRL is used in subsequent competition radioimmunoassays.
In those assays, 1×10 -6 to 1×10 -10 g of purified bPRL or to 10 0 to 10 -2 dilutions of bacterial lysates prepared as described above containing bPRL are pre-incubated with the appropriate dilution of anti-bPRL for 2 hours at room temperature, at which time 2.5×10 -4 to 3.5×10 -4 cpm of 125 I-bPRL is added and the subsequent reactions, centrifugation and washing are accomplished as described above.
When the bacterial lysate bPRL is added to a fixed amount of anti-bPRL the appropriate immune complexes are formed. The fixed amount of labelled bPRL added to the reaction mixture complexes with any anti-bPRL not previously bound to the bacterial lysate bPRL competitor. The amount of radioactivity in the resulting precipitate is inversely proportional to the amount of bPRL competitor present in the sample.
Current levels of expression as measured by RIA are 0.2-0.4 mg/OD-L of cells. This immunoassay thus indicates that the bacterial lysates do, indeed, contain the DNA sequence capable of synthesizing a polypeptide exhibiting one or more of the biochemical characteristics of bovine prolactin including the ability of the polypeptide to form antigen-antibody complexes.
EXAMPLE 7
The procedure for obtaining the cDNA sequence coding for chicken growth hormone is described in detail in Applicant's co-pending application Ser. No. 418,846, filed Sept. 16, 1982, Examples 1 through 3, therein.
The single-stranded DNA phage M13 is used as a cloning vector for forming single-stranded DNA templates from the double-stranded cDNA coding for chicken growth hormone. The sequence of cGH reveals the following structural components of the gene, which can be seen in cGH5 of FIGS. 3 and 4:
(1) a 5' untranslated sequence of 52 bases;
(2) a 26 amino acid leader;
(3) a 190 amino acid mature protein; and
(4) a 3' untranslated sequence of approximately 100 bases.
The cDNA cGH sequence is not readily accessible for securing direct and optimal expression of the mature form of cGH in a microbial host due to the presence of the approximately 78 base sequence 5' to the cGH coding region which sequence presumptively codes for a 26 amino acid leader region, and a 5' untranslated region. To secure such expression the cGH coding region should be provided with an initial ##STR28## codon, and inserted into a transformation vector at a site under control of a suitable promoter/regulator DNA sequence.
The sequence for approximately the first half (5' terminus) of the cGH protein coding DNA single strand in M13 includes a single BamHI recognition site as illustrated below: ##STR29##
DNA inserts containing the 5' portion of the cGH protein coding region (including an initial ATG and lacking bases coding for the leader sequence) may be prepared by the following method of the present invention using the single-stranded M13 DNA. As illustrated in FIG. 3, insert cGH5 containing the entire cGH gene is cleaved with endonucleases PstI and BamHI, which reaction produces two strands of cDNA, one strand containing the 5' end of the cGH gene and a larger strand containing the 3' end. The shorter strand is then incubated with and incorporated into single-stranded M13mp8 to form cGH17.
A. Insert No. 1
A partially duplexed DNA oligonucleotide primer is manufactured by the process described in Example 3. The partially double-stranded Primer A thus manufactured has the following sequence: ##STR30##
This Primer A contains an XbaI site and an ATG adjacent the TTC phenylalanine codon. Two ##STR31## base pairs are located at the beginning of the manufactured primer, providing a "safety region" to protect the XbaI restriction site in the primer sequence from digestion by S1 nuclease. The single-stranded M13 DNA (cGH17) containing the 5' terminus of the cGH gene (PstI-Bam HI) is incubated with the manufactured Primer A, whereby a hybrid double-stranded region is formed (see result of Primer A arrow in FIG. 3). A standard sequencing reaction using 1.0 μg of single-stranded DNA template from the M13 phage in a 25 μl reaction with DNA Polymerase I (Klenow) is carried out at room temperature for 20-30 minutes as described for bPRL. The short strand of the primer is in a three-fold excess over the long strand to help assure that the primer remains as a duplex at its 5' terminus during S1 nuclease treatment. After this primer extension, the reaction is phenol-extracted, CHCl 3 extracted, and ethanol precipitated.
The DNA, now comprising the duplex primer 5' to 3' along the single-stranded M13 template approximately 1-2kb is re-suspended in an S1 nuclease buffer and subjected to the process described above for bPRL. The nick between Primer A base (C) and the original strand base (A) is repaired when the sequence is inserted into a bacterial vector by T 4 DNA ligase.
The double-stranded Primer A:cGH DNA is re-suspended in BamHI cleavage buffer (6 mM Tris, pH 7.4, 6 mM MgCl 2 , and 150 mM NaCl) and digested with 10 units of BamHI in a 25 μl final volume at room temperature for 40 minutes, forming a BamHI sticky end on the 3' end (of the Primer A:cGH DNA). Upon completion of this reaction, the DNA is extracted and precipitated. pBR322 DNA cleaved with BamHI and PvuII is isolated from an agarose gel and ligated to a 5M excess of Primer A-synthesized DNA. The resulting transformants are tested by plasmid analysis for the XbaI site introduced by Primer A and the BamHI cleavage site. One clone, cGH16, (see FIG. 4) was selected for expression testing.
B. Insert No. 2
Another cGH insert containing the 5' portion of the gene suitable for incorporation into a storage vector is manufactured in a procedure similar to that of procedure A, above. Primer B in this case, however, contains no duplex portion and primes at a position 3' to the first codon of the cGH gene (see result of Primer B arrow in FIG. 3).
Primer B has the following sequence: ##STR32## A useful feature of this primer is that the 5' terminus contains the 3' half of a PvuII recognition site, so that following primer extension, treatment with S1 nuclease, and cleavage with BamHI, the resulting fragment can be easily stored in pBR322 (PvuII-BamHI) as similarly described for bPRL.
EXAMPLE 8
An expression vector is then constructed by a process generally consisting of incorporation of the 3' region of the cGH gene and a 5' region developed according to Example 7A (see FIG. 3). The construction process described below is illustrated in FIG. 4.
A pBR322-derived plasmid (Pint-γ-txB4) which contains a tryptophan (Trp) promoter sequence and an XbaI site 3' to a Shine/Delgarno sequence followed by a gene coding for γ-Interferon is used as the expression vector because it contains the necessary unique restriction sites to carry out the following constructions. The 3' end of the cGH gene is introduced into the expression vector by first cutting the vector at the unique HindIII and BamHI sites and the phosphatasing it (calf intestine phosphatase; Sigma). The vector is then ligated to sea plaque (Marine Colloids) purified cGH DNA (BamHI-PvuII small fragment derived from plasmid cGH5), as well as M13mp8 RF DNA which had been cut with both HindIII and HincII to provide a linker needed to join the PvuII end of the cGH5 DNA to the HindIII cut site of Pint-γ-txB4. The resulting colonies upon transformation (E.coli HB101) are screened by mini plasmid preparation with the appropriate enzymes to detect clones containing the BamHI-PvuII cGH fragment and the HindIII-HincII linker fragment from M13mp8 RF DNA. Clone cGH14 is isolated for further manipulations.
The next step in the construction involves removing as much as possible of the 3' untranslated portion of the clone (cGH14) and the copy number control region of the plasmid (located near the PvuII site). Clone cGH14 is cut with NcoI and PvuII (5 μl reaction). The reaction volume is then raised to 25 μl to end fill the NcoI end using Klenow in a standard sequencing buffer with 50 μm dNTP's at room temperature for 30 minutes. After completion of the reaction the DNA is phenol and chloroform extracted, then ethanol precipitated. The DNA is re-suspended in a standard ligase buffer and ligated with T 4 DNA ligase. The ligation reaction is transformed as before and colonies are screened for plasmids now lacking the NcoI-PvuII fragment.
One clone, cGH3, is used in the subsequent and final construction step. cGH3 DNA is cleaved with XbaI and BamHI, then phosphatased. This DNA is then ligated to cGH16 DNA (an end product of Primer A reaction described in Example 7A, FIG. 3, containing the 5' portion of cGH), digested with XbaI, BamHI and HaeIII. After transformation clones are screened for containing a complete cGH coding region by digestion with XbaI and BamHI. The plasmid from one clone, designated cGH-T21, containing a trp promoter regulator, an initial ATG, and the complete cGH coding region, is transformed into E.coli K-12 strain C600 (ATCC No. 39182) for expression analysis.
While the foregoing illustrative examples relate generally to the modification of a double-stranded cGH DNA sequence and a bPRL cDNA sequence, it will be apparent that such modifications may be made on any double-stranded DNA sequence. Additionally, it will be apparent that expression in yeast and other microorganism cells of such modified DNA sequences is also contemplated.
As one example, the methods of the present invention could easily have been superimposed on those illustrated in FIG. 4 of European Patent Application No. 054330, to develop a double-stranded cDNA sequence specifying a predominant portion of mature thaumatin but easily stored in pBR322. In the procedure illustrated in the application, after the step of modification of the 3' end of the portion of the preprothaumatin to delete protein coding regions beyond the terminal 5'-GCC-3' codon (specifying alanine) and to add a translation termination codon, modifications were performed at the 5' end. Specifically, a single-stranded primer of the sequence GCC ACC TCC GAG was employed to hybridize to the 5' sequence coding for the initial four amino acids of mature thaumatin and effect deletion of a multiple amino acid "leader" sequence. As indicated previously, the double-stranded DNA product of that procedure is not readily stored or amplified and must be promptly associated with a double-stranded linker by a separate reaction if it is to be inserted in an expression vector.
According to the present invention, a twelve base pair single-stranded primer having the sequence CTG CTC CTA CAC may be employed which is complementary to the base sequence toward the 5' end of the thaumatin-coding region beginning with the C in the codon for arginine at amino acid position 8 (base position +23). Note that the 5' end of the primer includes the base sequence CTG, providing the 3' half of a PvuII recognition site. The double-stranded sequence obtained as a product of polymerization of the hybrid sequence formed includes a half of a PvuII site making the sequence easily storable in pBR322. Alternatively, if a vector has a unique HpaI site, a primer beginning with the AAC of the asparagine codon (amino acid position 7) could be used as an alternative to the PvuII primer. AAC provides the 3' half of a HpaI restriction site.
Numerous other modifications and variations in the invention are expected to occur to those skilled in the art upon consideration of the foregoing description. Consequently, only such limitations as appear in the appended claims should be placed on the invention.
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Disclosed are methods for selective modification of double-stranded DNA sequences facilitating their storage and incorporation into expression vectors. Manufactured partially double-stranded DNA primers are hybridized to complementary regions of single-stranded forms of DNA sequences to be altered. Desired, selectively modified double-stranded DNA sequences are then formed by DNA polymerization and specific nuclease digestion of undesired double- and single-stranded regions. Illustratively provided are DNA sequences useful in the microbial expression of bovine prolactin and other valuable polypeptides such as avian growth hormone.
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Cross Reference to Related Application
This application is a continuation of pending prior application Ser. No. 07/657,746, filed on Feb. 18, 1991; which is a continuation-in-part of application Ser. No. 07/596,271 filed on Oct. 12, 1990, now U.S. Pat. No. 5,363,599.
BACKGROUND OF THE INVENTION
This invention relates to particle impact treatment of fibers and fabric in order to enhance the dyeability characteristics of fabrics or fibers that are difficult and sometimes impossible to dye such as aromatic polyamides (polyaramids).
Polyaramids have been found to be well-suited for applications in areas exposed to transient or continuous high temperatures and for personal protection such as in ballistic vests and in cut resistant gloves. In areas where high temperature resistance and dyeability are important, fabrics constructed of relatively low modulus aramid fibers such as those of poly(meta-phenylene isophthalamide) are used. In areas where high strength is of primary importance, as in ballistic protection, fabrics of high modulus aramid fibers such as poly(para-phenylene terephthalamide) are used. Fabrics constructed of such high modulus aromatic polyamide fibers, hereinafter known as HM-aramid fibers, are extremely difficult to dye, while lower modulus aramid fibers, hereafter known as LM-aramid fibers can be dyed to dark shades only by use of suitable swelling agents or carriers. Therefore, it would be highly desirable to modify the HM-aramid fibers to produce a dyeable fabric with minimal degradation to physical properties. Likewise, it would be desirable to modify LM-aramid fibers to produce a fabric dyeable without recourse to environmentally problematic chemical agents.
The present invention solves the above problems in a manner not disclosed in the known prior art.
SUMMARY OF THE INVENTION
Method and apparatus for modifying fiber or fabric by impaction with particles that create axially aligned micro-cracks and increased porosity allowing penetration of dyestuffs into the fiber or fabric without the need for swelling agents or carriers.
It is an advantage of this invention to provide a highly textured fiber surface.
It is another advantage of this invention to provide axially directed cracks and enlargement of pore size for acceptance of dyestuff.
Yet another advantage of this invention is that highly structured fabrics such as para-aramids are equally susceptible to treatment as less structured meta-aramids.
Still another advantage of this invention is that after treatment, aramid fiber is readily dyeable in basic or disperse dyes for medium and dark shades and sulfur dyes for light shades.
Another advantage of this invention is that the hand of the fabric or fiber is relatively unchanged.
Yet another advantage of this invention is that the fiber may be treated in either fiber or fabric form.
In another advantage of this invention, when treated in fabric form, the reduction in strength is minimal with very few broken filaments with the treatment affecting primarily the top layer of fibers.
These and other advantages will be in part obvious and in part pointed out below.
BRIEF DESCRIPTION OF THE DRAWINGS
The above as well as other objects of the invention will become more apparent from the following detailed description of the preferred embodiments of the invention, which when taken together with the accompanying drawings, in which:
FIG. 1 is a cross-sectional view of a particle impact assembly constructed in accordance with the present invention;
FIG. 2 is a cross-sectional view of an alternative embodiment of a particle impact assembly;
FIG. 3 is a cross-sectional view of one of the gas jets shown in FIG. 2 employed in practicing the present invention;
FIG. 4 is a photomicrograph of KEVLAR® (para-polyaramid) at 2500 X magnification after being treated by bicarbonate of soda;
FIG. 5 is a photomicrograph of KEVLAR® (para-polyaramid) at 2500 X magnification after being treated by bicarbonate of soda;
FIG. 6 is a photomicrograph of KEVLAR® (para-polyaramid) at 2500 X magnification after being treated by bicarbonate of soda;
FIG. 7 is a photomicrograph of NOMEX® (meta-polyaramid) at 2500 X magnification after being treated by bicarbonate of soda;
FIG. 8 is a photomicrograph of NOMEX® (meta-polyaramid) at 2500 X magnification after being treated by bicarbonate of soda; and
FIG. 9 is a photomicrograph of NOMEX® (meta-polyaramid) at 2500 X magnification after being treated by bicarbonate of soda.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now by reference numerals to the drawings, and first to FIG. 1, a particle impact apparatus is generally indicated by numeral 1. Fabric 2 is supplied, with its full open width, to the apparatus 1 by a standard fabric delivery means that is not shown. The fabric 2 is directed through an acute angle by means of contact with a back-up bar 5. There is a treatment area 6 in which particles are accelerated to just below sonic velocity by means of an acceleration chamber 10 and then impacted against the fabric 2. Acceleration chamber 10 is formed by a top plate 8 and a bottom nozzle plate 9 that extends across the width of the fabric 2, which for most fabrics is about two meters. The apparatus 1 is surrounded by a housing (not shown) to contain the particle laden air.
The ambient particle laden air is recycled through the apparatus 1 by being drawn into the acceleration chamber 10 by means of filter 12 and orifice 15. The filter 12 is attached to the top plate 8 by means of bolt 14. The amount of air brought into the acceleration chamber 10 is regulated by the gap 17 between the top plate 8 and the top nozzle plate 19. This gap 17 is set by a first spacer plate 20. Compressed air used to accelerate the particles is delivered by manifold 22 to converging/diverging nozzle 26 via a plurality of communicating passages 28 and 30 to sub-manifold 32, which is formed by top nozzle plate 19, bottom nozzle plate 9, base plate 24, and a second spacer plate 25. The thickness of the second spacer plate 25 determines the gap of the converging/diverging nozzle 26.
The manifold 22 is connected to the base plate 24 by means of a series of bolts 34 or any other equivalent means of interconnection such as conventional hardware, adhesives, welding, brazing, and so forth as is typical throughout this application. A series of bolts 36 attach the base plate 24 to the bottom nozzle plate 9. A series of bolts 38 connect the top plate 8 to the first spacer plate 20 and top nozzle plate 19. There is another series of bolts 40 connecting the top nozzle plate 19 to the second spacer plate 25 and to base plate 24.
The gap between the back-up bar 5 and the exit of the acceleration chamber 10 is controlled by actuator 42. Raising the back-up bar 5 reduces and then eliminates the treatment. Lowering the bar 5 to nearly block off the exit of acceleration chamber 10 produces enough back pressure to reverse the flow through orifice 15 and filter 12, thereby cleaning the filter 12.
An alternative particle impact apparatus is generally indicated by numeral 51, as shown in FIGS. 2 and 3. Fabric 53 is supplied open width over idler roll 55 and then under treatment back-up roll 56, past input seal 57 and then into the air driven vortex that is generally indicated by numeral 59. Treatment is effected by impact with near sonic velocity large particles 62 and small particles 61 in the impact area 68. The fabric 53 then exits the vortex 59 past exit seal 64 and over idler roll 66. The input seal 57 is "J"-shaped and facing downward toward the cylindrical wall 72 of the apparatus 51. The exit seal 64 is also "J"-shaped and relatively similar to the input seal 57 but facing upward away from the cylindrical walls of the apparatus 51. Both input seal 57 and exit seal 64 are held in position by a combination of dual blocks 99 on each side of each seal 57 and 64 and interconnecting bolts 70 that connect the seals 57, 64 to the cylindrical wall 72. A conventional fabric delivery, take-up and tensioning means are used and not shown.
Referring now to FIG. 3, a gas jet is generally indicated by numeral 74 with gas being supplied from a gas hose 77, which is preferably constructed out of rubber or any other material that can carry gas at high pressure, and is connected to tube inlet 76 into the manifold 78 that supplies pressurized gas to through passage 79 that communicates with sub-manifold 80 that ejects the gas by means of a converging/diverging nozzle 81. This converging/diverging nozzle 81 is formed by top plate 82 and base plate 83. Both of these plates 82 and 83 are attached to the curved plates that form the cylindrical wall 72 by means of locking screws 84 and 85 respectively. The top plate 82 is fastened to the base plate 83 by means of screw 86. The manifold 78 is fastened to the base plate 83 by means of screw 87. Any equivalent structure that creates a gas nozzle tangential to the interior of the curved surface may be used.
Referring again to FIG. 2, the near sonic air stream ejected from the converging/diverging nozzle 81 is forced into the spiralling path 88, where most of its original energy is lost before escaping the air driven vortex 59 via exhaust passage 90 that extends along the longitudinal axis of the cylindrical exhaust manifold 91. It can be appreciated that the centrifugal effects of the air driven vortex 59 is to preferentially drive the large sonic velocity particles 62 against the cylindrical wall 72. The air exhausted by the exhaust manifold 91 is relatively enriched in small treatment particles 61. The exhausted particles 61 are replenished by a cylindrical supply tube 94.
Both apparatus 1 and 51 have the advantage of treating fabric continuously across the width and of recycling the treatment particles. Apparatus 51 has the additional advantage of efficiently utilizing all of the energy in the air stream and is immune to clogging.
The type of particle or particles to be used in both embodiments should be small, high speed particles, that could be in the form of a powder, which have a hardness comparable to or less than that of the fiber. This is so the fiber may undergo repeated impacts with breaking or cutting. A preferred substance is bicarbonate of soda due to its low cost, fine particle characteristics, nontoxicity, low hardness (2.5 on Mohs scale) and ease of removal due to its soluble nature.
Upon treatment, a highly textured fiber surface is formed with axially aligned cracks. This treatment is equally effective for a highly structured para-aramid such as KEVLAR® fabric and the less structured meta-aramid NOMEX® both manufactured by E. I. dupont Nemours and Co. and described in U.S. Pat. No. 4,198,494. FIGS. 4, 5 and 6 are photomicrographs at 2500X magnification of KEVLAR® fibers after impact treatment and FIGS. 7, 8 and 9 are photomicrographs at 2500 X magnification of NOMEX® fibers after impact treatment.
The treated Kevlar® fabric is readily dyeable without carriers by either basic or disperse dyes in medium to dark shades, as well as by sulfur dyes in light shades. Dyeing begins at one hundred degrees Celsius, but pressure dyeing is preferred at one hundred and thirty degrees Celsius for speed and uniformity. It is believed that the microcracks between the microfibrils that make up the fiber as well as the mechanical enlargement of pore size, are both induced by the impact treatment and responsible for the dyeability of the fibers.
When the treatment is performed in fabric form, the reduction in strength is minimal due to the fact that only the top layer of fibers is treated, with very few broken filaments. The hand of the fabric is virtually unchanged by impact treatment. Impact treatment may be effectuated in either fabric or fiber form.
The dyeability of the fabric is significantly reduced by the presence of water during treatment. It is believed that the plasticization of the less crystalline regions between the micro-fibers retards the formation of micro-cracks.
It is not intended that the scope of the invention be limited to the specific embodiment illustrated and described. Rather, it is intended that the scope of the invention be defined by the appended claims and their equivalents.
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Method and apparatus for modifying fabric and fiber by impaction with particles that create axially aligned micro-cracks and increased porosity allowing penetration of dyestuffs into the fiber or fabric without the need for swelling agents or carriers. The apparatus includes a container, pressurized gas supplied to a first inlet, particles supplied to a second inlet, and an outlet passage through which the particles and gas are supplied to a textile fabric.
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CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser. No. 13/653, 305 (filed on Oct. 16, 2012), which claims benefit under 35 USC 119 (e) of U.S. Provisional Patent Application No. 61/617,726, filed on Mar. 30, 2012. The entire content of each related application is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to integrated circuits and more specifically to a mixer utilized in such circuits.
BACKGROUND
[0003] Mixer circuits are utilized in a variety of types of integrated circuits to combine signals in many electronic applications. For consumer electronics applications it is always desirable to minimize the mixer circuit cost as well as improve the circuits overall efficiency. It is known that in certain circumstances when the utilizing such circuits there are undesired spurs or signals that are produced that can affect the overall performance of the mixer.
[0004] FIG. 1 is a diagram a mixer circuit 100 that may produce these undesirable spurs or signals environment. As is seen, the circuit 100 includes a mixer 102 which is coupled to a power amplifier (PA) driver 104 . The PA driver 104 is in turn coupled to a power amplifier (PA) 106 . As seen a baseband (BB) signal is provided to the mixer 102 in conjunction with the local oscillator (LO) signal to provide an output signal of f LO +f BB .
[0005] As is seen there is also an undesired spur at f LO − 3 f BB . This undesired spur can become an issue when transmitting data in certain frequency bands under certain standards. For example, under the Long Term Evolution (LTE) telecommunication standard, the LTE band 13 operation can be affected by these spurs as they can fall in the public safety band. Accordingly, it is desirable to remove the inter-modulation signal shown as IM3 to ensure proper operation of a device that utilizes a mixer circuit. It is known that the IM3 signal can be removed in a variety of ways. One way to address this issue is to couple a band pass filter 202 between the mixer 102 ′ and the PA driver 104 ′ as shown in FIG. 2 . This does reduce the IM3 signal however at a cost of complexity and increased cost because the band pass filter 202 adds to the overall size of the circuit and can significantly increase the chip area and power consumption.
[0006] Another way to address this issue is to couple a saw filter 302 between the PA driver 104 ″ and the PA 106 ″ as shown in FIG. 3 . In this solution, as is seen the saw filter 302 also removes or reduces the undesired spur. However the addition of the saw filter 302 requires more packaging area and is relatively more expensive and power consumption.
[0007] Another way to address this issue is to replace the mixer 102 with an active harmonic rejection mixer (HRM) 402 as shown in FIG. 4 . Although the active HRM 402 does not have the problems associated with the other solutions above it still has problems in certain environments. To describe these issues in more detail refer now to the following description in conjunction with the accompanying figures.
[0008] FIG. 5A is a circuit schematic of a conventional active harmonic rejection mixer 500 . The active harmonic rejection mixer 500 includes three mixer elements 502 , 504 and 506 coupled in parallel. Each of the mixer elements 502 , 504 and 506 each received differential input signals. Each of the mixer elements 502 - 506 transmits signals with different phases such that the vector sum of the undesirable harmonics (in this example, the 3′ rd and the 5 th ) is zero. Mixer element 502 receives an in phase LO signal. Mixer element 504 receives a LO signal that is 45° out of phase with the signals received at mixer element 502 . Mixer element 506 receives a LO signal that is 90° out of phase with the signal received at mixer element 502 . In this circuit 500 , the even order harmonics are rejected due to the differential operation of the circuit. The third and fifth harmonics as illustrated in FIG. 5B are cancelled by the output vectors of the mixer paths and by sizing the transistors in the mixer elements 502 - 506 in an appropriate manner. Accordingly, the signal for the fundamental harmonic is unattenuated. By contrast the third order harmonic and the fifth order harmonic signals are zero. For example as is seen, the transistors in mixer element 504 are larger than in the mixer elements 502 and 506 .
[0009] The system requires unwanted signal (harmonics) subtraction, cancellation or rejection of multi-paths. In this type of system, a mismatch in multi-paths (X 1 , X 2 and X 3 ) results in residual error in subtraction, and sets a rejection limitation. Accordingly, the problem with the active HRM 500 is that it has limited linearity, requires high-power and utilizes a large area.
[0010] Another type of conventional mixer is a passive voltage sampling mixer. FIG. 5C is a diagram of a conventional passive voltage sampling mixer 550 . The mixer 550 includes receives differential I and Q signals at their inputs 552 a - 552 d. In this embodiment, the differential I signals 552 a and 552 b are separated by 180° and the differential Q signals 552 c and 552 d are separated by 180°. The outputs of the signals are coupled to an amplifier 554 . The LO clocks 552 a - 552 d are non-overlapping and are provided utilizing a 25% duty cycle as shown in FIG. 5D . The circuit 550 does have high linearity, has negligible power consumption and utilizes a small area on a chip or package; however it still has the undesirable spur component.
[0011] Accordingly, what is desired is to provide a system and method that overcomes the above issues. The system should be simple, cost effective, easily implemented and adaptable to existing environments. The present invention addresses such a need.
SUMMARY OF THE INVENTION
[0012] One exemplary mixer circuit includes mixer elements having 3 N pairs of differential inputs. There are non-overlapping clock signals provided to the mixer elements which have a duty cycle equal to or less than 33⅓ percent, and N is a positive integer. Output differential signals of the mixer elements do not contain third order harmonic content of the non-overlapping clock signals.
[0013] Another exemplary mixer circuit includes a first mixer element and a signal combining device. The first mixer element has 3N pairs of differential inputs, wherein there are non-overlapping clock signals provided to the first mixer element which have a duty cycle equal to or less than 33⅓ percent, and N is a positive integer. The signal combining device combines outputs from the first mixer element wherein an output signal of the signal combining device do not contain third order harmonic content of the non-overlapping clock signals.
[0014] Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a diagram of a first embodiment of a conventional mixer circuit.
[0016] FIG. 2 is a diagram of a second embodiment of a conventional mixer circuit.
[0017] FIG. 3 is a diagram of a third embodiment of a conventional mixer circuit.
[0018] FIG. 4 is a diagram of a fourth embodiment of a conventional mixer circuit.
[0019] FIG. 5A is a circuit schematic of a conventional active harmonic rejection mixer.
[0020] FIG. 5B illustrates the cancellation of the third and fifth order harmonics in the mixer of FIG. 5A .
[0021] FIG. 5C is a diagram of a conventional passive voltage sampling mixer.
[0022] FIG. 5D illustrates the non-overlapping clock signals associated with the mixer of FIG. 5C .
[0023] FIG. 6A is a diagram that illustrates that if a 33% duty cycle for the LO is utilized there is no third order harmonic component and its associate equation.
[0024] FIG. 6B is a diagram of a first embodiment of a mixer circuit in accordance with the present invention.
[0025] FIGS. 6C illustrates a three phase generation circuit in accordance with an embodiment.
[0026] FIGS. 6D illustrates the waveforms associated with the three phase generation circuit of FIG. 6C .
[0027] FIG. 7 is a diagram of a first embodiment of a symmetric voltage sampling mixer circuit in accordance with the present invention.
[0028] FIG. 8 is a diagram of a second embodiment of a symmetric voltage sampling mixer circuit in accordance with the present invention.
[0029] FIG. 9 is a diagram that compares a system that utilizes a mixer circuit in accordance with the present invention with a system that utilizes an active harmonic rejection mixer circuit.
DETAILED DESCRIPTION
[0030] The present invention relates generally to integrated circuits and more specifically to a mixer utilized in such circuits. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.
[0031] A method and system in accordance with the present invention eliminates undesired harmonic contents at 3 fLO and fLO- 3 fBB in a straightforward manner. The elimination of the harmonic contents at 3 fLO and fLO- 3 fBB is accomplished via utilizing a sampling mixer which runs at a substantially 33⅓ percent (e.g. , about 33%) duty cycle.
[0032] In so doing, there is no harmonic content at 3 fLO and hence the undesirable component at fLO- 3 fBB is eliminated. To describe the features of the present invention in more detail refer now to the following figures in conjunction with the accompanying drawings.
[0033] The system and method in accordance with the embodiments of the present invention has several advantages that are listed below.
[0000] 1. Enable low noise for SAW-LESS system
2. Significantly reduced current consumption compared with existing solutions
3. Requires smaller chip area
4.Does not need digital compensation
5. Does not need any calibration (manufacturing, on-chip)
6. More robust over process and temperature.
[0034] To describe the features of the embodiments of the present invention in more detail refer now to the following figures in conjunction with the accompanying drawings.
[0035] FIG. 6A is a diagram that illustrates that if a 33% duty cycle for the LO is utilized there is no third order harmonic content and its multiple harmonic components and its associated equation. As is seen from the Figure a 33% duty cycle LO waveform does not have a third order harmonic component. Hence, it can be used this signal can be utilized by a voltage sampling mixer as illustrated in FIG. 6B to eliminate the third order harmonic ( 3 fLO). FIG. 6B is a diagram of a first embodiment of a mixer circuit 600 in accordance with the present invention. As is seen the mixer circuit 600 includes first and second amplifiers 602 and 604 which receive differential I and Q inputs. The amplifiers 602 and 604 provide signals to the mixer the LO signal is provided into which comprises switches which are controlled by LO which is divided into three clocks at 0, 120 and 240 degrees as shown in FIG. 6D .
[0036] Accordingly a three phase mixer is provided in this embodiment to eliminate the undesired harmonic contents at 3 fLO, fLO- 3 fBB and I-Q quadrature image signal of a signal. With this type of circuit the undesired harmonic contents at 3 fLO and fLO- 3 fBB is eliminated.
[0037] Furthermore the mixer 600 has higher overall gain as Q doesn't have to be scaled down by 1/sqrt(3).
[0038] The clocks can be generated in a variety of ways. FIGS. 6C illustrates a three phase generation circuit 650 that comprises conventional D flip-flops 654 and coupled to a divide by three LO 652 that are coupled in series. As is seen, the output signal from the LO 652 is an input to the flip flop 654 and the output signal from the flip flop 654 is an input to the flip flop 656 . Therefore LO 652 provides the LO 0 signal, flip flop 654 provides the LO 120 signal and flip flop 656 provides the LO 240 signal.
[0039] Referring back to FIG. 6B , the I amplifier 602 has a gain of 1 and the Q amplifier 604 has a gain of 1 divide the square root of 3. The I amplifier 602 is driving one set of differential switches 606 and the Q amplifier 604 is driving two sets of differential switches 608 a and 608 b. Therefore I and Q amplifiers are not balanced. This is not desirable because (a) I and Q paths are imbalanced resulting in worse I-Q image rejection; (b) LO signals are not differential and hence no second harmonic rejection at 2 fLO. To address this issue it is important to provide symmetry between the two drivers.
[0040] FIG. 7 is a diagram of a first embodiment of a symmetric voltage sampling mixer circuit in accordance with the present invention. The sampling mixer circuit 700 includes first and second passive mixer elements 702 a and 702 b. Mixer element 702 a includes one pair of differential I inputs and two pairs of differential Q inputs while mixer element 702 b includes one pair of differential Q inputs and two pairs of differential I inputs. Therefore the inputs on the two mixer elements are balanced. The outputs of the mixer elements 702 a and 702 b are coupled to drivers 706 a and 706 b respectively. The outputs of drivers 706 a and 706 b are coupled to an output network 710 in which the differential outputs of the drivers 706 a and 706 b are constructively added together. Mathematically, let the positive output to be denoted as +vo, and the negative output to be denoted as −vo. The 710 output will be +vo−(−vo)=2vo. That is, the positive differential outputs are coupled together and the negative differential outputs are coupled together.
[0041] As is seen, each of the mixer elements 702 a and 702 b comprise three pairs of differential switches that are driven by three non-overlapping LO (LO 1 , LO 2 and LO 3 ) clocks which are at a 33⅓ duty cycle. Accordingly a six phase mixer is provided in this embodiment to eliminate the undesired harmonic contents at 3 fLO, fLO- 3 fBB and I-Q quadrature image signal of a signal. With this type of circuit the undesired harmonic contents at 3 fLO and fLO- 3 fBB are eliminated and the circuit is balanced for the baseband signals (LO is still not balanced). Furthermore the mixer 700 has higher overall gain as Q doesn't have to be scaled down by 1/sqrt(3).
[0042] Although this mixer operates effectively to remove the undesired harmonic contents at 3 fLO and fLO- 3 fBB and I-Q quadrature image signal it does not effectively remove second order ( 2 fLO) harmonic content. Accordingly what is needed is a mixer that minimizes all harmonic contents described above.
[0043] FIG. 8 is a diagram of an embodiment of a symmetric voltage sampling mixer circuit in accordance with the present invention that minimizes both the 2 fLO harmonic contents and third 3 fLO and hence LO- 3 fBB harmonic contents. Mixer circuit 800 includes the same topology as described in FIG. 7 but also includes two more mixer elements 804 a and 804 b. Mixer element 804 a includes one pair of differential I inputs and two pairs of differential Q inputs while mixer element 804 b includes one pair of differential Q inputs and two pairs of differential I inputs. Therefore the baseband inputs on the two mixer elements 804 a and 804 b are also balanced. The outputs of the mixer elements 804 a and 804 b are coupled to drivers 806 a and 806 b respectively to provide two differential outputs. The differential outputs of drivers 806 a and 806 b are coupled to an output network 710 ′. As is seen, each of the mixer elements 804 a and 804 b comprise three pairs of differential switches that are also driven by three non-overlapping LO (LO 1 , LO 2 and L 03 ) clocks which are at a 33⅓ duty cycle and which are 180 degrees out of phase with the LO clocks of the mixer elements 702 a and mixer element 702 b respectively. The differential outputs of the drivers 706 a, 706 b , 806 a and 806 b are coupled together in a manner such that the fundamentals harmonic (at fLO) are constructively added, while the even order harmonics (2*N*fLO, N=1,2,3 . . . ) are subtracted from each other. For example referring to the outputs of driver 706 a and driver 806 a, the positive output signal from driver 706 a is coupled to the negative output signal of 806 a. By using this topology the even order harmonic output of the drivers 806 a and 806 b cancels the even order harmonic LO output of the drivers 706 a and 706 b, respectively..
[0044] In so doing a mixer is provided that has no third order and even order harmonics. The drivers 706 a ′, 706 b ′, 806 a, and 806 b also provide for reverse isolation if passive mixer elements are utilized to ensure accurate performance of the mixer circuit 800 .
[0045] Accordingly, a low power, small area, and high linearity voltage sampling mixer is proposed which does not have harmonic contents at 3 fLO and fLO- 3 fBB. The harmonic contents at 3 fLO and fLO- 3 fBB of the mixer is eliminated by using a three phase mixer which uses voltage sampling on non-overlapping clocks and thereby achieving high linearity. A 12 phase LO can be used to make baseband I-Q and LO symmetric and differential.
[0046] To describe the advantages of this mixer in a particular environment refer now to the following description in conjunction with the accompanying figure. FIG. 9 is a diagram that compares a system that utilizes a mixer circuit in accordance with the present invention with a system that utilizes an active harmonic rejection mixer circuit. The environment is LTE band 13 which requires that the harmonic contents at fLO- 3 fBB be suppressed to an extremely low level. In the conventional architecture there are several issues that need to be addressed to allow for adequate performance which will be described in detail hereinbelow.
[0000] 1. To improve LO- 3 f BB spur reduction for Band 13 , signal reduction is required before the mixer 908 , and extra gain is required after the mixer 908 . This degrades noise performance.
2. Because of (1), an external SAW filter 914 is required to filter noise for RX de-sensitization.
3. To recover the signal reduction due to (1), and insertion loss due to (2), the RF amplifier requires higher power consumption (typical 2× the current). Therefore an extra gain stage is usually required, resulting in larger area.
4. To meet with Band 13 LO- 3 f BB spur, extra RF filtering 910 is required to reduce f 3 LO at the mixer output, hence reducing intermediation (IM3) product between desired signal and 3 LO in the RF amplifier 912 . This filter 910 is usually LC based to achieve the required filter. Therefore an inductor is required, that also results in larger area.
5. Extra digital compensation 902 is required to suppress the Band 3 LO- 3 f BB spur. Since the spur level is very low, on-chip calibration is prone to error. Manufacturing calibration is usually required. Furthermore, the Band 13 LO- 3 f BB spur is temperature sensitive, limiting the performance of digital compensation.
6. Without the invention, all (1) to (5) have to be employed simultaneously to meet the Band 13 LO- 3 f BB requirement wherein the new architecture does not need any of these elements.
[0047] Accordingly, a low power, small area, and high linearity voltage sampling mixer is proposed which does not have third harmonic ( 3 fLO) output. The I-Q quadrature image signal is eliminated by using a three phase mixer which uses voltage sampling on non-overlapping clocks and thereby achieving high linearity. A 12 phase LO can be used to make I and Q symmetric and differential.
[0048] Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.
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One mixer circuit includes mixer elements having 3N pairs of differential inputs. There are non-overlapping clock signals provided to the mixer elements which have a duty cycle equal to or less than 33⅓ percent, and N is a positive integer. Output differential signals of the mixer elements do not contain third order harmonic content of the non-overlapping clock signals. Another mixer circuit includes a first mixer element and a signal combining device. The first mixer element has 3N pairs of differential inputs, wherein there are non-overlapping clock signals provided to the first mixer element which have a duty cycle equal to or less than 33⅓ percent, and N is a positive integer. The signal combining device combines outputs from the first mixer element wherein an output signal of the signal combining device do not contain third order harmonic content of the non-overlapping clock signals.
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PRIORITY
[0001] This application claims priority to a Provisional Application No. 60/987629 titled “Particle Beam Assisted Modification of Thin Film Materials” and filed on Nov. 13, 2007; a Provisional Application No.: 60/987667 titled “Particle Beam Assisted Modification of Thin Film Materials” and filed on Nov. 13, 2007; and a Provisional Application 60/987,650 titled “Particle Beam Assisted Modification of Thin Film Materials” and filed on Nov. 13, 2007, each of which is incorporated in entirety by reference.
RELATED APPLICATIONS
[0002] This application is related to co-pending application Ser. No. ______ titled “Particle Beam Assisted Modification of Thin Film Materials” and filed on ______, and co-pending application Ser. No. ______ titled “Particle Beam Assisted Modification of Thin Film Materials” and filed on ______. Each of the co-pending applications are incorporated in entirety by reference.
FIELD
[0003] This disclosure relates to a system and technique for processing a substrate, more particularly, to a system and technique for forming a substrate crystalline phase.
BACKGROUND
[0004] The widespread adoption of emerging technologies such as flat panel displays (FPD) and solar cells depends on the ability to manufacture electrical devices on low cost substrates. In manufacturing FPD, pixels of a typical low cost flat panel display (FPD), are switched by thin film transistors (TFT) which may be typically manufactured on thin (−50 nm thick) films of amorphous silicon deposited on inert, glass substrates. However, improved FPDs demand better performing pixel TFTs, and it may be advantageous to manufacture high performance control electronics directly onto the panel. One advantage may be to eliminate the need for costly and potentially unreliable connections between the panel and external control circuitry.
[0005] Current FPDs contain a layer of Si that is deposited onto the glass panel of the display via a low temperature deposition process such as sputtering, evaporation, plasma enhanced chemical vapor deposition (PECVD), or low pressure chemical vapor deposition (LPCVD) process. Such low temperature processes are desirable, as the panel used to manufacture FPD tends to be amorphous and has glass transition temperature of approximately 600° C. If manufactured above 600° C., the panel may have a non-uniform or uneven structure or surface. Higher temperature tolerant glass panels such as quartz or sapphire panel exist; however, the high cost of such glasses discourages their use. Further cost reduction would be possible if cheaper, lower temperature tolerant glass or plastic panels could be used.
[0006] The low temperature deposition process, however, does not yield optimal Si film. As known in the art, solid Si has three common phases: amorphous, poly-crystalline, and mono-crystalline phases. If Si is deposited at low temperature, the deposited Si film tends to be in an amorphous phase. The channels of thin film transistors based on amorphous Si film may have lower mobility compared to those on either poly-crystalline Si or mono-crystalline Si films.
[0007] To obtain a polycrystalline or mono-crystalline Si layer, the panel may undergo further processes to convert the amorphous Si film to either polycrystalline or mono-crystalline film. To obtain a panel with poly-crystalline Si film, the panel may undergo an excimer laser annealing (ELA) process. An example of the ELA process may be found in more detail in U.S. Pat. No. 5,766,989. To obtain a panel with larger crystals, the panel may undergo a process known as Sequential Lateral Solidification (“SLS”) process. An example of SLS process may be found in U.S. Pat. No. 6,322,625. Although ELA and SLS processes may result in a panel with mono-crystalline or poly-crystalline Si thin film, each process is not without disadvantages. For example, excimer lasers used in both processes may be expensive to operate, resulting in an expensive TFT. In addition, the duty cycle may not be optimum for the best conversion of amorphous Si into crystalline Si. Further, the excimer laser may have pulse-to-pulse variations and spatial non-uniformity in the delivered power which may affect the uniformity of the processes. There may also be intra-pulse non-uniformity which may be caused by for example, self-interference of the beam. Such inter-pulse and intra-pulse non-uniformity may result in Si films with non-uniform crystals.
[0008] As such, new methods and apparatus for particle processing for the cost effective and production worthy manufacture of high quality crystalline materials on low temperature substrates are needed.
SUMMARY
[0009] Several examples of a method for processing a substrate are disclosed. In a particular embodiment, the method may include: disposing a substrate having an upper surface and a lower surface on a platen contained in a chamber; generating a plasma containing a plurality of charged particles above the upper surface of the substrate, the plasma having a cross sectional area equal to or greater than a surface area of the upper surface of the substrate; applying a first bias voltage to the substrate to attract the charged particles toward the upper surface of the substrate; introducing the charged particles to a region extending under entire upper surface of the substrate; and initiating, concurrently, a first phase transformation in the region from the amorphous phase to a crystalline phase.
[0010] The present disclosure will now be described in more detail with reference to exemplary embodiments thereof as shown in the accompanying drawings. While the present disclosure is described below with reference to exemplary embodiments, it should be understood that the present disclosure is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other fields of use, which are within the scope of the present disclosure as described herein, and with respect to which the present disclosure may be of significant utility.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In order to facilitate a fuller understanding of the present disclosure, reference is now made to the accompanying drawings, in which like features are referenced with like numerals. These figures should not be construed as limiting the present disclosure, but are intended to be exemplary only.
[0012] FIG. 1 is a block diagram of various mechanisms through which amorphous material may transform into crystalline material.
[0013] FIG. 2 shows a graph of the depth of Ar ions introduced to a Si substrate according to one embodiment of the present disclosure.
[0014] FIG. 3 shows block diagram of a system for processing a substrate according to one embodiment of the present disclosure.
[0015] FIG. 4 shows a block diagram of a particular exemplary system of the system shown in FIG. 3 .
[0016] FIG. 5 shows a block diagram of another system for processing a substrate according to another embodiment of the present disclosure.
[0017] FIG. 6 shows a graph comparing the temperature of a substrate irradiated with a laser beam or a particle beam.
[0018] FIG. 7 shows a graph of the temperature of a substrate irradiated with a focused particle beams according to another embodiment of the present disclosure.
[0019] FIG. 8A-8B show a method that can be incorporated into manufacturing of a solar cell according to another embodiment of the present disclosure.
[0020] FIG. 9A-9C show another method that can be incorporated into manufacturing of a solar cell according to another embodiment of the present disclosure.
[0021] FIG. 10A-10D show another method that can be incorporated into manufacturing of a solar cell according to another embodiment of the present disclosure.
DETAILED DESCRIPTION
[0022] To overcome the above-identified and other deficiencies of existing laser-based thin film materials processing, several embodiments of particle based processing are disclosed. The particle-based processing may be advantageous as it may promote non-equilibrium processes. In addition, particle parameters may be controlled with much more precision than parameters of the laser. Examples of the particle parameters may include spatial parameters (such as beam size and current densities), particle flux (and/or beam current), particles species, and particle dose etc. . . .
[0023] In the present disclosure, several embodiments are disclosed in context to a beamline ion implantation system and a plasma based substrate processing system such as, for example, a plasma assisted doping (PLAD) system or plasma immersion ion implantation (PIII) system. However, those of ordinary skill in the art should recognize that the present disclosure may be equally applicable to other systems including other types of particle based system. The term “particles” used herein may refer to sub-atomic, atomic, or molecular particles, charged or neutral. For example, the particles may be protons; ions, atomic or molecular; or gas clusters.
[0024] In the present disclosure, several embodiments are described in context to a substrate. The substrate may be a wafer (e.g. Si wafer) or a substrate comprising a plurality of films. In addition, the substrate may be an elemental substrate containing only one element (e.g. Si wafer or metal foil); a compound substrate containing more than one element (e.g. SiGe, SiC, InTe, GaAs, InP, GaInAs, GaInP; CdTe; CdS; and combinations of (Cu, Ag and/or Au) with (Al, Ga, and/or In) and (S, Se and/or Te) such as CuInGaSe, CuInSe2, other group III-V semiconductors and other group II-VI compounds); and/or an alloy substrate. The material contained in the substrate may be metal, semiconductor, and/or insulator (e.g. glass, Polyethylene terephthalate (PET), sapphire, and quartz). Further, the substrate may be a thin film substrate containing multiple layers (e.g. SOI). If the substrate comprises multiple layers, at least one of the layers may be a semiconducting film or a metallic film, whereas another one of the films may be an insulator. The semiconducting or metallic film may be disposed on a single insulating film or, alternatively, interposed between a plurality of insulating films. Conversely, the insulating film may be disposed on a single semiconducting or metallic film or, alternatively, interposed between multiple semiconducting or metallic films or both.
Phase Transformation
[0025] The most rapid mechanism for crystallization of thin amorphous layers is solid phase epitaxial re-growth (SPER). In SPER, amorphous Si may transform to crystalline Si by extending an underlying, pre-existing, extensive crystal layer. This scenario is commonly encountered during annealing of a surface layer of a crystalline Si wafer after it has been amorphized by ion implantation. The present disclosure relate to processing an amorphous substrate in which an extensive pre-existing lattice does not exist and which phase transformation occur via crystal nucleation prior to the growth of the crystals. Referring to FIG. 1 , there is shown a block diagram of various mechanisms through which a material without extensive pre-existing lattice may transform from an amorphous phase into a crystalline phase. As known in the art, the crystalline phase may be categorized as a poly-crystalline phase or a mono-crystalline phase. The poly-crystalline phase may sometimes be further subdivided into different categories (such as multi-, micro-, nano-crystalline etc) depending on the crystal size. However, such a distinction may not be important in the context of this disclosure, and may not be necessary to describe FIG. 1 . Accordingly, these phases may be referred herein collectively as a crystalline phase.
[0026] As illustrated in FIG. 1 , the phase transformation from the amorphous phase to a crystalline phase may occur via various mechanisms. For example, the transformation may occur via melting and solidification mechanism 100 a and solid phase crystallization (SPC) transformation mechanism 100 b. In the melting and solidification mechanism 100 a and SPC mechanism, the transformation may occur via nucleation of crystallites and growth of the crystallites. In the SPER mechanism, the transformation may occur by growth on the extensive pre-existing crystal lattice.
[0027] In the melting and solidification mechanism 100 a, energy in the form of radiation, heat, or kinetic energy, may be introduced to a portion of the amorphous substrate and melt the portion. If the condition of the molten region is adequate to induce nucleation (e.g. supercooling), crystals may nucleate as described by the classical nucleation theory. The crystals may nucleate via two schemes. The crystals may nucleate heterogeneously on pre-existing seeds. The pre-existing seeds may be grain boundaries of pre-existing crystals that did not melt upon introduction of the energy. The pre-exiting seeds may also be the boundary between the molten region and adjacent solid region. If the pre-existing seeds are absent, the crystals may nucleate homogeneously. Upon nucleation, the crystals may grow until the growth is halted.
[0028] In the solid phase transformation mechanism 100 b, the phase transformation may occur despite the absence of the melting. For example, crystals may nucleate in the region introduced with energy, and the nucleation may be followed by the growth of the nucleated crystals. As in the case of the melt process, nucleation during SPC can occur heterogeneously if pre-existing seeds exist, or homogeneously if such seeds are absent.
Particle Assisted Processes
[0029] In the present disclosure, particles may be introduced to a substrate to induce the phase transformation. The phase transformation may be that from the amorphous phase to one of the polycrystalline and/or mono-crystalline phases. In addition, the phase transformation may occur via nucleation and growth of the crystals. To induce the transformation, the particles may be introduced near the upper surface of the substrate, the lower surface of the substrate, or a region between the upper and lower surfaces, or a combination thereof. If the substrate comprises two or more different materials, the particles may be introduced to a region near the interface of the different materials.
Particle Species
[0030] Numerous types of particles may be introduced to induce the phase transformation. For example, the particles that are chemically and/or electrically inert with respect to the substrate may be used. However, chemically and/or electrically active material may also be used. As noted above, the particles may be charged or neutral sub-atomic particles, atomic particles, or molecular particles, or a combination thereof. In some embodiments, molecular particles are preferred. In other embodiments, cluster particles are preferred. Molecular and cluster particles may be preferred as they may be introduced to the substrate at much higher dose and energy. In particular, molecular and cluster particles introduced to a substrate may disintegrate on impact, and the kinetic energy of the particles may be shared in the ratio of the atomic masses of the particle atoms. The overlapping collision cascades may achieve result similar to introduction of atomic particles at much higher dose rate. Due to their greater mass, the molecular particles may also be introduced to the substrate at much higher energy. The generation of atomic and molecular species in implanters, PLAD and PIII will be familiar to those skilled in the art. A detailed description of the generation of cluster particles may be found in U.S. Pat. No. 5,459,326, which is incorporated in entirety by reference.
[0031] The choice of the particles introduced to the substrate may also depend on the effect of the particles on the substrate. Some characteristics and illustrative examples are shown in Table 1.
[0000]
TABLE 1
Some possible choices of ion species
Characteristic
Example species
Electrically
Ge, Si, C, F, N H, He, Sn, Pb,
inactive in
hydrocarbon molecules, molecules
silicon
containing C and two or more other
elements, hydrides of silicon such as
tetra-silane, molecules containing Si and
two or more other elements
Dopants
B, P, As, Sb, In, Ga, Sb, Bi,
Shallow Junction
C, F
Co-implant species
Amorphizing
Noble Gases (including He, Xe), Ge, Si
Strain producing
Ge, C
Bandgap
Yb, Ti, Hf, Zr, Pd, Pt, Al
engineering
Passivating
H, D
Defect Pinning
N
Crystallization
Ni, metals
catalysts
Depth and Energy
[0032] When the particles are introduced to the substrate, the kinetic energy of the particles may be transferred to the substrate. The magnitude of the transferred kinetic energy may depend on the size, mass, and energy of the particles. For example, heavy ions introduced to a substrate may experience more nuclear stopping than lighter ions. When the particles lose their kinetic energy via the nuclear stopping mechanism, the mechanism tends to form defects such as, for example, dangling bonds, vacancies, and di-vacancies, whose presence may enhance the crystallization process. At the same time, kinetic energy transferred to the substrate via electronic stopping may cause crystallization.
[0033] Depending on the energy of the particles, the location of the particles delivery, and the properties of the substrate (e.g. thermal conductivity, heat capacity and melting temperature of the substrate), nucleation of crystals may be initiated at the upper surface of the substrate; the lower surface of the substrate; the region between the upper and lower surfaces; or near the interface of different materials. Thereafter, the phase transformation may continue in a direction away from the location where the transformation is initiated.
[0034] Unlike the radiation based phase transformation, energy deposited to the substrate via the particle introduction may peak at the surface or, alternatively, below the surface. In addition, the particles may be introduced to the substrate at a constant energy. Alternatively, the particles may be introduced at varied energies. For example, the energy of the particles introduced to the substrate may change while the particles are being introduced. The change in the energy may occur continuously or in a sequence. If a beam-line particle system is used, the particle energy may be changed during the particle introduction using acceleration or deceleration voltage associated with beam-line systems described herein. If PLAD, PIII, or other plasma based system is used, the energy may be changed during the introduction by varying the voltage applied to the substrate.
[0035] Referring to FIG. 2 , there is a graph showing depth and energy of particles introduced to a substrate, according to one embodiment of the present disclosure. In the present embodiment, Ar ions are implanted into Si thin film. As shown in FIG. 2 , the points joined by the line represent the average range of the Ar ions and the vertical error bars represent the straggle in depth. The total range of all ions can then be estimated by the sum of the average range plus a multiple (one or more) of the straggle. If the Ar ions were required to be contained within a surface layer of Si of known depth, the maximum energy may be estimated from this curve. The inset chart is a larger representation of the low energy scale of the main chart.
Spatial and Temporal Profile
[0036] In addition to the energy, the spatial and temporal profile of the particles may be controlled. For example, the particles may be introduced as a particle beam, and the beam may have constant or varied beam current density (i.e. number of particles in a predetermined area for a predetermined time). The current density may be adjusted by changing the particle current and/or beam size; the beam dwell time by controlling the beam and/or substrate scanning speeds and/or pulse length; and the beam duty cycle (e.g. time between beam pulses or return time if the beam and/or substrate are scanned).
[0037] In the present disclosure, the particles may be introduced to the substrate continuously or periodically in sequence. If the particles are introduced as a particle beam, the beam may have various shapes. For example, the particles may be introduced as a ribbon beam or a spot beam. The ribbon beam may have a ribbon shape or a shape where the dimension of the beam along one direction is larger than along another direction. Such a ribbon beam may be wider than the substrate or, alternatively, narrower than the substrate. The spot beam, meanwhile, may have a dimension smaller than the substrate. If used, the spot beam may be scanned, either magnetically or electrostatically at a rate of approximately 100-1000 Hz, to resemble the ribbon beam.
[0038] If the cross section of the beam, whether a ribbon beam or a spot beam, is smaller and does not cover the entire surface area of the substrate, the beam may be additionally scanned relative to the substrate. For example, the beam may be scanned along 2 directions, along the width direction and length direction, such that the particles may be introduced to the entire surface of the substrate. In the present disclosure, such scanning may be achieved by translating the substrate along the length and width directions relative to a stationary beam or by translating the beam along the length and width directions relative to the stationary substrate. By controlling the rate of the relative scanning of the beam and/or the substrate, the phase transformation of the substrate may be controlled.
[0039] In addition, the particle beam introduced to the substrate may be a focused beam or a non-focused beam. In addition, the particles beam may be uniform or non-uniform along its cross section. For example, a ribbon beam may have a higher current density at its leading edge followed by a trailing edge having a lower current density, or vice versa. The non-uniform beam may have other intensity profiles. It is believed that a non-uniform beam may enhance the nucleation process and the growth process. For example, the non-uniform beam may have an intense leading edge to initiate nucleation, followed by a less intense trailing edge. For example, the high density portion of the beam may initiate the phase transformation by melting the substrate, and the low density portion of the beam may enhance the extent of the transformation by controlling the solidification of the molten region.
[0040] Further, more than one beam may be operated and introduced to the substrate either simultaneously or sequentially. If more than one beam is used the beam may be introduced to the entire width and/or length of the substrate at one time.
Direction
[0041] The particle assisted phase transformation may have some advantage in orienting the crystal growth and/or crystal shapes. In the present disclosure, the particles may be introduced to the substrate at various angles. Introduction of the particles at various angles may be achieved by the tilting the substrate relative to the beam and/or the beam may be tilted relative to the substrate.
[0042] In one embodiment, the particles may be introduced to the substrate at 0° (i.e. perpendicular to the surface of the substrate). The particles introduced at 0° may preferentially destroy {200} grain boundaries that may limit electrical conductivity in FPDs. Alternatively, the particles may be introduced at other angle, for example, 7°.
Substrate Condition
[0043] In addition to the parameters of the particles, the conditions of the substrate may be adjusted before, during, or after introduction of the particles. For example, the temperature of the substrate may be adjusted. In one embodiment, the substrate may be heated to, for example, approximately 500° C. prior to or during the introduction of the particles. Heating the substrate may mitigate thermal shock caused by the particle beam. In addition, heating the substrate may induce formation of larger crystals. For example, heating the substrate may cause the region introduced with the particles to cool at a slower rate (as this region may largely loose its energy through conduction into the substrate).
[0044] The crystallization may be enhanced if the substrate were cooled below room temperature. For example, the substrate may be cooled to a temperature ranging from about 0° C. to about −100° C. In addition, cooling the substrate may prevent the structure of the insulating film from being unstable.
[0045] When the particles are introduced to the substrate, the substrate may be in vacuum or at atmospheric pressure. The vacuum pressure may be higher than those usually associated with ion implantation (i.e. pressure higher than 10-4 mbar) to reduce pump cost.
Exemplary Systems
[0046] Referring to FIG. 3 , there is shown a block diagram of an exemplary system 300 for processing a substrate according to one embodiment of the present disclosure. The system 300 may be a beam-line particle system 300 . The system 300 may comprise an ion source 302 ; an extraction system 304 ; an acceleration system 306 ; optional beam manipulation components 308 ; and a neutralization system 310 . In addition, the system 300 may comprise an end station 312 communicating with the neutralization system 310 . The end station 312 may comprise a window 314 and one or more loadlocks 316 and 318 . Within the end station 312 , a platen that supports a substrate 322 may be positioned. In addition, one or more of substrate translation, cooling and/or heating sub-system 324 may be disposed in the end station 312 .
[0047] In the present disclosure, the ion source 302 may be a Bernas type, with indirectly heated cathode. Those of ordinary skill in the art will recognize that the ion source 302 may also be other types of ion source. Meanwhile, the extraction system 304 may be a single slit or, alternatively, a multiple slit extraction system 304 . The extraction system 304 may be translatable in one or more orthogonal directions. In addition, the extraction system 304 may be designed to extract a temporally constant beam current. In addition, the extraction system 304 may extract the particle continuously or intermittently. The extraction system 304 may also focus the particle beam or beamlets to allow a desirable spatial and/or temporal beam profiles. The particles beam extracted via the extraction system 304 may have energy of approximately 80 keV.
[0048] If higher energy is required, the system 300 may include an acceleration system 306 that may accelerate the particle beam. The system 300 may also include one or more additional, optional beam manipulation components 308 to filter, scan, and shape the particles to a particle beam. As illustrated in FIG. 4 , a specific example of the system 300 , the optional beam manipulation components 308 may include a first magnet analyzer 406 , a first deceleration (D1) stage 408 , a second magnet analyzer 410 , and a second deceleration and a second deceleration (D2) stage 412 . In the present disclosure, the first magnet analyzer 406 , a substantially dipole magnet, may filter the particles based on the particles' mass and energy such that particles of undesired mass and/or energy will not pass through the magnet analyzer 406 . Meanwhile, the second magnet analyzer 410 , another substantially dipole magnet, may be configured to collimate the particles into a particle beam having desired shape (e.g. ribbon) and/or dimension. D1 and D2 deceleration stages 410 and 412 may manipulate the energy of the particles passing through such that the particles may be introduced to the substrate at a desired energy. In one embodiment, the D1 and/or D2 may be segmented lenses capable of minimizing the space charge effect and maintaining spatial integrity of the beam.
[0049] Although not shown, the beam manipulation components may also include one or more substantially quadrupole magnets or einzel lenses to focus the beam. Further, the beam manipulation components may also include magnetic multipoles or rods such as described in U.S. Pat. Nos. 6,933,507 and 5,350,926 to control the uniformity of the beam profile.
[0050] Returning to FIG. 3 , the charge neutralization system 310 , according to the present embodiment, may also be included to reduce charge build-up in the substrate 322 . The charge neutralization system 310 may be one or more systems of hot filament, or microwave, or rf driven type, such as that described in U.S. patent application Ser. No. 11/376850. Alternatively, the charge neutralization system 310 may be an electron source.
[0051] In the end station, the environment around the substrate may be controlled in order to prevent, for example, deposition of other materials on the substrate or to promote passivation to enhance the crystallization process. To control the environment, the end station 312 may include a thin foil window or a differentially pumped aperture 314 , through which the particles may enter, and one or more loadlocks 316 and 318 , through which the substrate may be admitted. The loadlocks 316 and 318 may be replaced by one or more differentially pumped stages through which the substrate may be admitted.
[0052] The end station 312 may also contain substrate movement, cooling, and heating subsystem 324 . Examples of sub-system 324 may include a chiller, a heat source, a roplat capable of translating/rotating the substrate along several axes. Specific examples of the chiller may be found in U.S. patent application Ser. No. 11/504,367, 11/525,878, and 11/733,445, each of which is incorporated by reference in entirety. Specific examples of the heat source may be a laser, flash lamp, platen providing fluid heating, resistive heat source, or those described in U.S. patent application Ser. Nos. 11/770,220 and 11/778,335, each of which is incorporated by reference in entirety.
[0053] To monitor the process and substrate parameters/conditions, one or more parameters/conditions measuring components may also be included near the substrate 322 . Such components may be coupled to one or more controllers, and the controllers may control the parameters/conditions of the substrate and/or the particles based upon the signals from the measuring components.
[0054] Referring to FIG. 5 , there is shown another exemplary system for processing a substrate according to another embodiment of the present disclosure. In particular, the system 500 may be a PLAD, PIII system, or other plasma based substrate processing system. PLAD system 500 may comprise a chamber 501 including top section 502 and a lower section 504 . The top section 502 may include a first dielectric section 506 that extends in a generally horizontal direction and a second dielectric section 508 that extends in a generally vertical direction. In one embodiment, each dielectric section 506 and 508 may be ceramic that is chemically resistant and that has good thermal properties. The top section 502 may also include at least one or more antennas 510 and 512 . The one or more antennas 510 and 512 may be, for example, a horizontal antenna 510 and/or a vertical antenna 512 . In one embodiment, the horizontal antenna 510 may be a planar coil having multiple windings, whereas the vertical antenna 512 may be a helical coil of multiple windings. At least one of the antennas 510 and 512 may be electrically coupled to a power supply 514 via an impedance matching network 516 .
[0055] On the lower section 504 of the system 500 , a platen 520 and a substrate 522 supported by the platen 520 may be positioned at a predetermined height below the top section 502 . However, it is also contemplated that the platen 502 ad the substrate 522 may be positioned in the top section 502 . A bias voltage power supply 524 may be electrically coupled to the platen 520 to DC or RF bias the platen 520 .
[0056] In operation, at least one of the antennas 510 and 512 may be RF or DC powered by the power source 514 . If only one of the antennas 510 and 512 is RF or DC powered, the other one of the antennas 510 and 512 may be a parasitic antenna. The other one of the antennas 510 and 512 may be a parasitic antenna as it is not electrically coupled to the power source 514 . Instead, the other one of the antennas 510 and 512 is magnetically coupled to the antenna that is powered by the power source 514 . Alternatively, both of the antennas 510 and 512 may be powered by the power source 514 with an RF current. Thereafter, at least one of the antennas 510 and 512 induces the RF currents into the system 500 via the first and second dielectric sections 506 and 508 . The electromagnetic fields induced by the RF currents may covert the gas contained in the system 500 into plasma. Meanwhile, the bias voltage power supply 524 may bias the platen 520 to attract the charged particles in the plasma to the substrate 522 . Additional details of the system 500 may be found in U.S. patent application Ser. No. 11/766984; application publication No. 2005/0205211; application publication No. 2005/0205212, and application publication No. 2007/0170867, each of which is incorporated in entirety by reference.
Optional Components
[0057] In addition to the components described above, the exemplary systems 300 - 500 may optionally include one or more masks between the particle source (e.g. ion source or plasma) and the substrate. If included, the mask may preferentially be a carbon (C) based material, Si based material (e.g. SiC), or refractory metal, such as W or Ta, containing material. However, other materials may also be used. Such a mask may have one or more aperture having various shapes including chevron shape to control the shape of the beam incident on the substrate.
FPD
[0058] Hereinafter, description of several applications of the particle induced phase transformation is provided. As noted above, the particles may be introduced into a Si layer of a thin film substrate to induce the phase transformation from the amorphous to the crystalline phase. For purpose of clarity, a comparison of the particle induced phase transformation is made with the ELA process.
[0059] In the present embodiment, the particles may be directed to an FPD having an amorphous Si film of about 500 Å thick disposed on an insulating film. The insulating film may be, for example, amorphous glass or Corning 1737 glass having a thickness of about 0.7 mm, quartz, plastic, or sapphire. However, those of ordinary skill in the art will recognize that other types of insulating film may also be used.
[0060] In ELA process, a single laser pulse may deliver an energy pulse of 360 mJ/cm 2 in a 12 nanosecond long pulse. This equates to a power density of 3×10 10 W/m 2 . If an Ar ion beam is directed to the Si film, the beam may have an energy of 20 keV. With such energy, all of the directed Ar ions may not penetrate the substrate beyond the Si layer (see FIG. 2 ). If a ribbon shaped Ar particle beam is used, the beam may be assumed to have dimensions of 300 mm wide by 0.1 mm tall. With a beam current of 25 mA, this implies a power density of 1.7×10 7 W/m 2 .
[0061] In ELA process, the laser beam incident on the substrate may heat the Si layer to 1000° C., near the melting temperature of amorphous Si. Upon incidence, the laser beam may initiate at least a partial melting of Si layer. The thermal diffusivity for Si is relatively high, varying between ˜1 cm 2 /sec at room temperature and 0.1 cm 2 /sec at 1400K. Hence, even if the laser energy is absorbed in the top few nm of the Si surface, absent any latent heat effects, there may be a very small temperature gradient within the Si layer. Heat may diffuse from the Si into the glass. The diffusivity for the glass is small (˜0.005 cm2/s over a large temperature range), and so a large thermal gradient may exist across the thick glass layer. The results of the model shown in FIG. 6 , calculate that the glass even within 0.1 μm of the Si, does not reach above 500° C.
[0062] As the particle beam has a lower power density, the exposure time needed to deposit sufficient energy to heat the Si film may be higher (80 ms) compared to the laser (12 ns). In addition, as the heat deposited to the substrate via the particles may be lost to the insulating via thermal conduction, more energy may be needed to heat the Si film sufficiently. Under these assumptions, the insulating film within 50 μm of the Si may be heated above 600° C. Nevertheless, sufficient amount of the insulating may not be heated above its glass transition (or melting) temperature such that these conditions may be acceptable.
[0063] If the height of the ribbon beam were to increase to 1 mm, it may take approximately 2.4 seconds to sufficiently heat the Si film, in which time the peak temperature of the bottom of glass may reach 600° C. This example, compared to the 0.1 mm case in FIG. 7 , demonstrates the need to keep the power density of the beam as high as possible. This may be achieved by maintaining the beam area as small as possible, increasing beam current, and/or increasing the beam energy. The mass of the ion species may also be increased. The use of a molecular particle beam may be desirable as it allows the use of higher beam energies. At the same time, the higher beam energy may reduce additional detrimental effects such as space charge blow-up that may otherwise limit the beam currents and the beam focusing.
[0064] The particle beam irradiation may retain the solid Si in the amorphous phase, allowing melting to occur at 1300K. Crystalline Si does not melt until 1683K. Therefore if the amorphous Si undergoes crystallization before melting commences, more power may be required to completely melt the material. Also, liquid Si may reflect a portion of the laser radiation and so coupling power into the bulk of the Si may be difficult once the Si surface has melted. The presence of a particle beam during the cooling and crystallization phase may influence the production of high quality material.
Thin Film Solar Cell
[0065] The particle induced phase transformation described in the present disclosure may also be applied to manufacture of thin film solar cells. As known in the art, amorphous Si is a direct band gap material and may absorb light more efficiently than crystalline Si, an indirect band gap material. In addition, amorphous Si absorbs more light in the visible spectrum than crystalline Si. However, amorphous Si has lower electrical conductivity. As such, amorphous Si may preferably transform incident radiation to electrical current, whereas crystalline Si may preferably transfer the generated electrical current. Accordingly, the solar cell, according to the present embodiment, may preferably have a layer of amorphous Si above another layer of crystalline Si. Incident radiation at visible wavelengths may be efficiently converted into photocurrent in the amorphous Si. Light not converted in the amorphous layer (including infra-red radiation) may be converted into photocurrent in the crystalline Si.
[0066] Referring to FIG. 8 , there is shown a process that may be incorporated in preparing a substrate according to another embodiment of the present disclosure. In the present embodiment, the substrate may be a thin film solar cell with crystalline and amorphous layers. In another embodiment, the substrate may be a semiconducting layer of a FPD that is disposed on an insulating layer (not shown). As illustrated in FIG. 8A , an amorphous Si layer 802 may be deposited onto a glass layer (not shown). The Si layer 802 may have thickness of 1.5 μm, whereas the glass layer may have thickness of 3 mm. The particles 804 having a predetermined dose and energy may then be introduced to the amorphous Si layer 802 . As illustrated in FIG. 8B , the particles 804 may be introduced below the surface of Si layer to crystallize a lower portion of Si layer 802 , without inducing crystallization of the upper portion of amorphous Si layer 802 . The resulting substrate may be used in a solar cell having an amorphous Si layer 802 disposed on the crystal Si layer 806 .
[0067] Referring to FIG. 9 , there is shown a process that may be incorporated in preparing a substrate according to another embodiment of the present disclosure. In the present embodiment, the substrate may be a thin film solar cell with crystalline and amorphous layers. In another embodiment, the substrate may be a semiconducting layer of a FPD that is disposed on an insulating layer (not shown). As illustrated in FIG. 9A , an amorphous Si layer 902 may be deposited onto a glass layer (not shown). Thereafter, particles 904 having a predetermined dose and energy may be introduced to the amorphous Si layer 902 to crystallize the entire Si layer 906 ( FIG. 9B ). As illustrated in FIG. 9C , a plurality of particles of second species 908 , energy, and dose may be introduced to the substrate to amorphize a layer near the surface of the crystalline Si layer. The resulting solar cell may have an amorphous top Si layer 904 and a crystalline lower Si layer 902 .
[0068] Referring to FIG. 10 , there is shown a process that may be incorporated in preparing a substrate according to another embodiment of the present disclosure. In the present embodiment, the substrate may be a thin film solar cell with crystalline and amorphous layers. In another embodiment, the substrate may be a semiconducting layer of a FPD that is disposed on an insulating layer (not shown). As illustrated in FIG. 10A , an amorphous Si layer 1002 may be deposited onto a glass layer (not shown). Thereafter, particles 1004 having a predetermined dose and energy may be introduced to the amorphous Si layer 1002 to crystallize a sub-layer 1006 within the Si layer 1002 ( FIG. 10B ). Although FIG. 10B illustrate a sub-layer disposed near the upper surface of the Si layer 1002 , those of ordinary skill in the art should recognize that the sub-layer 1006 may be positioned near the upper surface, near the lower surface, or anywhere between the upper surface and the lower surface of Si layer 1002 .
[0069] After forming the crystalline sub-layer 1006 , one or more of the crystals in the sub-layer 1006 may be grown away from the sub-layer 1006 until the entire Si layer 1002 may be crystallized. The crystals may be grown via one of furnace annealing, rapid thermal annealing (RTA), flashlamp annealing, and laser annealing. Alternatively, the crystals may be grown by particle assisted annealing. For example, the same or another types of particles (not shown) having another predetermined dose and/or another predetermined energy to the region below the crystallized sub-layer to extend the grain boundary of one or more crystals toward the lower surface of the substrate. In the process, the entire Si layer 1002 may contain one or more crystals having grain boundaries that extend in a vertical direction. The present embodiment may also include an optional amorphizing step to amorphize a portion of the newly crystallized Si layer 1006 . For example, the particles 1010 may then be introduced to the newly crystallized Si layer 1002 to amorphize at least a portion of the newly crystallized Si layer 1002 ( FIG. 10D ) to form an amorphous sub-layer 1012 . In the present disclosure, the particles introduced to the newly crystallize Si layer 1002 the same particles as those used to crystallize the previous amorphous Si layer 1002 . Alternatively, the the particles introduced to the newly crystallize Si layer 1002 may be different from those used to crystallize the previous amorphous Si layer 1002 . The above process may be used to crystallize a thick amorphous Si layer.
[0070] The particle induced phase transformation may also be used to manufacture an efficient polycrystalline Si solar cell. The grain boundaries of crystals may be efficient sites for gettering impurities, such as metal contaminants. In addition, grain boundary may serve as a barrier for charge carriers' mobility, inhibiting the carriers from traveling through the boundary. Accordingly, polycrystalline solar cells having multiple crystals, thus multiple grain boundaries, may have relatively low electrical conductivity if the grain boundaries are located across the path of the charge carriers. In the polycrystalline solar cells, electrical current generated at the upper surface must be transported to contact areas, which are generally located at the lower surface of the solar cell. If the grain boundaries in the polycrystalline solar cells are positioned across the path of the charge carriers, the efficiency of the solar cells may be lowered. As such, it may be desirable to manufacture polycrystalline solar cells having grain boundaries oriented in parallel manner relative to the path of the charge carriers.
[0071] To manufacture an efficient polycrystalline solar cell, an amorphous Si substrate may be prepared. Thereafter, the upper surface of the Si layer may be crystallized, and the crystals may grow downward per solid phase epitaxial regrowth (SPER). The ion energy may be chosen so that the power density delivered to the substrate may be maximized. This may correspond to an energy of between 40 to 100 kev, where typical ion beam systems can extract the maximum beam currents from an ion source and where space charge effects are reduced for beam transport and focusing. Such an ion beam may cause crystallization near the surface of the silicon which in turn may seed SPER downwards until the whole layer is crystallized. The SPER may take place as part of the beam induced crystallization step, or in a further annealing step that may use one or more of furnace, RTA, flashlamp, laser or other annealing methods. The resulting substrate will likely to have crystals with vertically extending grain boundaries. Thereafter, particles of second species, energy, and dose may be introduced to the substrate to amorphize a layer near the surface of the polycrystalline substrate. The solar cell may then have a structure of amorphous Si layer above vertically extending polycrystalline Si layer. As noted above, such a solar cell will likely to convert radiation energy to electrical energy more efficiently, and, at the same time, transport the converted electrical energy more efficiently.
[0072] In the present disclosure, the size and orientation of the boundaries may be influenced by the choice of the particle beam conditions used to assist the crystallization of the top layer. Phosphorous may be a favorable species as it is a good getter species, and may be the dopant of choice for the solar cell. The direction of implant may be chosen to influence the grain orientation. The whole active layer may be implanted, or the surface layer may be implanted to create a top crystalline surface with few voids, and the rest of the substrate may be regrown by SPER.
[0073] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the foregoing description is by way of example only and is not intended as limiting. What is claimed is any feature detailed herein.
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Several examples of a method for processing a substrate are disclosed. In a particular embodiment, the method may include: disposing a substrate having an upper surface and a lower surface on a platen contained in a chamber; generating a plasma containing a plurality of charged particles above the upper surface of the substrate, the plasma having a cross sectional area equal to or greater than a surface area of the upper surface of the substrate; applying a first bias voltage to the substrate to attract the charged particles toward the upper surface of the substrate; introducing the charged particles to a region extending under entire upper surface of the substrate; and initiating, concurrently, a first phase transformation in the region from the amorphous phase to a crystalline phase.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to image editing devices, and more particularly, to an image editing device capable of displaying a read document for a user to edit the displayed content.
2. Description of the Related Art
U.S. Pat. No. 5,142,355 and Japanese Patent Laid-Open No. 63-223785 disclose methods of writing, in a memory, data to recognize closed regions read from a document, recognizing the closed regions by referring to the data and editing the regions.
According to these conventional methods, however, the result of editing the regions, in other words if the closed regions have been surely recognized is not available until a copy is output, and therefore copying errors frequently result.
Japanese Patent Laid-Open No. 5-94311 discloses an editing device incorporating image data into a memory, displaying the data in the memory onto a display, and editing the data on the display.
The conventional editing device is however encountered with a disadvantage that read images are stored in the memory by a single method, and therefore it is very difficult to recognize regions or particular colors from the stored images for image processing.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an image editing device capable of displaying a read document in a manner easy for a user to recognize.
Another object of the invention is to provide an image editing device permitting a user to access the result of editing images before a copy is output.
Yet another object of the invention is to provide an image editing device permitting a read image to be readily processed.
In order to achieve the above-described objects, an image editing device according to one aspect of the invention includes a unit for reading a document image and obtaining image data, a first storage unit for storing the obtained image data as image data to be displayed on a display, a processing unit for processing the obtained image data into data used for recognizing closed regions provided in the document image, and a second storage unit for storing the processed data.
More preferably, the image editing device further includes a unit for editing the document image based on the processed data, and a unit for displaying a result of editing based on the result of editing by the editing unit and the image data stored in the first storage unit.
According to the invention, a read document can be displayed on a display in a manner easy for a user to recognize by the function of the first and second storage units. Furthermore, the display of the editing result permits a user to know the result before a copy is output.
According to another aspect of the invention, the image editing device includes a unit for setting at least one of a plurality of modes, a unit for reading a document image and obtaining image data, a unit for storing the obtained image data according to a method based on the set mode, and a unit for editing the document image based on the stored image.
According to the invention, the obtained image data is stored based on the set mode, and therefore an image editing device making easier succeeding image processing can be provided.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a copying machine according to one embodiment of the invention;
FIG. 2 is a cross sectional view showing the copying machine shown in FIG. 1;
FIG. 3 is a block diagram showing a screen editor included in the copying machine shown in FIG. 1;
FIG. 4 is a block diagram showing a main portion of the copying machine shown in FIG. 1;
FIG. 5 is a block diagram showing the configuration of an editing area designation memory 626;
FIG. 6 is a view for use in illustration of the structure of editing area designation memory;
FIG. 7 is a table for use in illustration of how to use memory planes in the editing area designation memory;
FIGS. 8A and 8B show the relation between a read document and data stored in the memory;
FIGS. 9A and 9B show the relation between data stored in the area designation memory and an image displayed on an LCD;
FIG. 10 is a block diagram showing the configuration of a closed loop/marker detection/LCD display document memory 620;
FIG. 11 is a view for use in illustration of the structure of memory 620 in a black-and-white document mode;
FIG. 12 is a table showing how memory planes correspond to a document input to memory 620;
FIG. 13 is a flow chart for use in illustration of the processing of allocating memory planes;
FIG. 14 is a block diagram showing the configuration of a binarizing processing portion 628;
FIG. 15 is a diagram for use in illustration of a closing processing;
FIG. 16 is a block diagram showing the configuration of an LCD display color coding/marker color determination processing portion 632;
FIG. 17 is a flow chart for use in illustration of the procedure of operating the copying machine shown in FIG. 1;
FIG. 18 shows an example of an editing menu;
FIG. 19 shows images displayed when an operator presses the buttons in the editing menu;
FIG. 20 shows an image displayed when a coloring mode is selected;
FIG. 21 shows an image displayed during the processing of coloring a black-and-white document;
FIG. 22 shows an area designation tool;
FIG. 23 shows the shape of an R box;
FIG. 24 shows processings by the trace button;
FIG. 25 shows processings by the closed loop button;
FIG. 26 shows an image displayed in a marker editing mode;
FIG. 27 is an image displayed during marker editing;
FIG. 28 shows a marker area designation tool;
FIG. 29 is an image displayed when a color editing mode is selected;
FIG. 30 shows an image read from a color document and displayed;
FIG. 31 shows an image displayed when a registration processing is selected;
FIG. 32 shows an image displayed after the operator presses the touch panel as the image in FIG. 31 is displayed;
FIG. 33 is a flow chart for use in illustration of a routine of displaying images for operating the copying machine in FIG. 1; and
FIG. 34 is the continuation of the flow chart shown in FIG. 33.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, preferred embodiments of the invention will be described in conjunction with the accompanying drawings, in which like reference characters represent the same or corresponding portion.
FIG. 1 is a perspective view showing a digital color copying machine according to one embodiment of the invention.
Referring to FIG. 1, color copying machine 100 includes an automatic document feeder (ADF) for a large volume of documents, a sorter 400 for sorting copy sheets, a film projector 500 for making copies from a film document, a screen editor 600, characteristic to the color copying machine according to this embodiment, and a printer controller 700 connected to a personal computer or an EWS (work station) to use the copying machine as a color printer.
Screen editor 600 includes a color liquid crystal display (LCD) 115 which displays a read document and various operation menus for giving directions to the user in operation.
There is provided, on color LCD 115, a transparent tablet (touch panel) to detect coordinates indicated by the user, and the user can directly input coordinates on the color LCD to the machine using a pen 800.
FIG. 2 is a cross sectional view for use in illustration of the mechanism of the color copying machine shown in FIG. 1.
Referring to FIG. 2, the copying machine is roughly divided into an image reader portion 30 and a printer portion 20, each of which will be detailed below.
(1) Image Reader Portion 30
Image reader (IR) portion 30 includes a platen 31 to place a document, a scanner 32 to scan a document by exposure, an image sensor (CCD) 201 to sense light reflected from a document, an image signal processing portion 330 to process a signal from the image sensor, a print head (PH) control portion 335 to output a control signal to the printer portion based on a signal from the image signal processing portion, and a pulse motor 35 to drive scanner 32.
The image of a document placed on platen 31 is exposed to light and scanned, and light reflected from the image is photoelectrically converted by image sensor 201. The signal resulting from the photoelectric conversion is subjected to a prescribed processing in image signal processing portion 330, and digital image data for driving a laser diode is produced. Thus produced digital image data is transmitted to print head control portion 335.
(2) Printer Portion 20
Printer portion 20 is roughly divided into an image forming portion and a developing unit portion, and a sheet processing portion, each of which will be separately described.
(a) Image Forming Portion
The image forming portion includes a laser device 21 driven based on the digital image data transmitted from image reader portion 30, a photoreceptor drum 4 to write an electrostatic latent image, a developing unit 6 for development with toner, a transfer drum 10 to transfer an image onto a surface of a sheet, and a drum drive motor 22 to drive the photoreceptor drum and transfer drum.
Laser device 21 is driven based on input digital image data. By driving laser device 21, an electrostatic latent image forms on the surface of photoreceptor drum 4. The electrostatic latent image is developed with toner by developing unit 6, and transferred onto a surface of a printing sheet placed on transfer drum 10.
Note that photoreceptor drum 4 and transfer drum 10 are driven in synchronization with each other by drum drive motor 22.
(b) Developing Unit 6
Developing unit 6 includes a magenta developer 6M for development with magenta toner, a cyan developer 6C for development with cyan toner, a yellow developer 6Y for development with yellow toner, a black developer 6K for development with black toner, four toner hoppers for supplying toner of a color corresponding to each developer, and a developing unit motor 61 for moving developing unit 6 in upward and downward directions.
(c) Sheet Processing Portion
The sheet processing portion includes storage cassettes 42-44 for storing sheets for printing, and an intermediate storage portion 50 for temporarily storing a sheet.
A sheet taken out from any of storage cassettes 42-44 or a sheet supplied from intermediate storage portion 50 is sent to transfer drum 10 by a group of transport rollers and wound around transfer drum 10. Then, toner images on photoreceptor drum 4 (in four colors at most) are sequentially transferred onto the sheet.
The sheet with the transferred image is separated from transfer drum 10, followed by fixing at a fixing device 48 and discharged onto a discharge tray 49.
The machine is provided with a pair of timing rollers 45 for providing timing for registration at the time of transporting the sheet and a transfer belt 47.
Note that the group of transport rollers and transfer belt 47 are driven by main motor 41.
Transfer drum 10 is provided with a tip chuck claw for chucking the tip of a sheet, an attraction charger 11 electrostatically attracting the sheet to transfer drum 10, a roller 12, a press-roller 12 for press-holding the sheet, a transfer charger 14 for sucking a toner image appearing on the photoreceptor drum onto the sheet for transfer, dischargers 16, 17 for electrically discharging the transfer drum to separate the sheet therefrom after the toner image has been transferred (the toner images for four colors have been transferred in the case of full color development), and a separation claw 18 for removing the sheet from the transfer drum.
The sheet after the above printing steps is brought into intermediate storage portion 50.
Whether to transport the sheet after the printing steps to discharge tray 49 or to intermediate storage portion 50 is determined based on the switching of a transport path switch portion 53 provided in the path transporting the sheet after the fixing processing.
Another transport path switching portion 54 is provided in the transport path toward intermediate storage portion 50. Transport path switching portion 54 selects whether to store the sheet into intermediate storage portion 50 after transporting the sheet in a switched back manner by a reversing device 51, or directly into intermediate storage portion 50.
Such selection is made for the purpose of determining whether to transfer an image on the side of the sheet which has been already printed (such transfer mode is called "image overlapped mode") or to transfer the image on the back side (which is called "duplex copy mode"), when the sheet supplied from intermediate storage portion 50 is once again transferred to the transfer drum.
The transfer drum is further provided with a reference position sensor 13 for detecting the reference position of the transfer drum, and an actuator plate 13a for operating the reference position sensor.
The operations of their image reader portions and printer portions will be described later.
FIG. 3 is a block diagram showing an electronic circuit for image processing included in the screen editor in the copying machine shown in FIG. 1, and FIG. 4 is a block diagram showing an image processing circuit included in the main body of the copying machine. FIGS. 3 and 4 are connected at positions A, B and C.
Referring to FIG. 3, the screen editor includes the following elements.
(a) Binary Memory for Combining Images (618)
The memory 618 stores a binary signal of a signal representing the luminance of document information (Y). The image of a black-and-white document is stored in the memory, and used as character information when combined with a color document (character combining function).
(b) LCD Display Document/Closed Loop.Marker Detection Memory (620)
In the color document editing mode, the memory converts document information into data to be input to the color pallet of the LCDC (LCD Controller) for display on the LCD and stores the data thinned to 100 dpi. More specifically, the number of colors in a document image is reduced to the number which can be displayed on the LCD and stored.
In the black-and-white document editing mode, the memory thins binary signals of 1 bit black-and-white (closed loop detection) information, 3 bit color information (R, G, B, C, N, Y) and 4 bit black-and-white gradation (for display) in a document to 100 dpi for storing.
Document information within the memory is transferred to a VRAM by the CPU for display.
In the black-and-white editing mode, the CPU detects a closed loop, a marker point position, and a marker closed loop in the document based on the information within the memory and produces editing area designation information.
As described above, the memory advantageously changes the method of storing based on the mode selected.
(c) Editing Area Designation Memory (626)
In the memory, 16 kinds of editing area signals are set as bit map information by the CPU based on coordinate designation from closed loop.marker detection memory 620 and the touch panel 614 of the editor. The output of area signals is controlled separately among editing functions based on the editing area information within the memory.
(d) Texture Memory (622)
The memory stores various patterns read from documents for later use in the background or the like of a document, and data for processing background gradation. The background gradation processing data is set by the CPU. Based on image data stored in the memory, a color document is provided with patterns and the background gradation processing for a black-and-white document is performed. The memory has a maximum scanning cycle (horizontal scanning) of 128 dots, a vertical scanning cycle of 256 dots, and a gradation (luminance) of 256 levels.
(e) Patterning Memory (624)
The memory stores binary data in the form of patterns for patterning processing. The pattern form binary data stored in the memory are used for patterning a black-and-white document. The pattern form binary data in the memory is set by the CPU. The memory has a pattern size of 128 dots (horizontal scanning) and 256 dots (vertical scanning) and there are eight kinds of patterns.
(f) Binarizing Portion (628)
The binarizing portion writes a simple binary output of a write signal (Y) from document input data to binary memory 618 during prescanning. During image reproducing scanning, the simple binary output of write signal (Y) from the document input data is output to a substitute color data producing portion 640 as character region determination data.
During the image reproducing scanning, the binary outputs of luminance signal (Y) and color saturation signal (G) of the document input data are output to substitute color data producing portion 640 as base region determination data.
(g) Hemming Determination Portion (630)
The hemming/cut out of image data in the area designated by the editing area signal is determined, and the determination information is output to substitute color data producing portion 640. During the hemming determination, prescribed determinations are made for the following functions.
Hemming function: the hemming edge of a binarized input image is detected, and the edge determination information is output to the substitute color data producing portion.
Cut out function: the inner edge of the binarized input image is detected, and the edge determination information is output to the substitute color data producing portion.
(h) Marker Color Determination.LCD Display Image Data Coding Processing Portion (632)
In the black-and-white document editing mode, during prescanning, document input data is divided into seven kinds, i.e., black-and-white and colors (R, G, B, C, Y and M) and output to LCD display document/closed loop.marker detection memory 620.
In the color document editing mode, during prescanning, document input data is converted to color codes for LCD display, and output to the LCD display document/closed loop.marker detection memory 620.
Data is written into LCD display document/closed loop.marker detection memory 620 for each 4 lines in the vertical scanning valid period.
Marker color determination.LCD display is retrieved from an ROM using Y, Cr, Cb as address information. An ROM table (256K×8 bits) is installed for coding image data for marker color determination.LCD display.
(i) 1/4 Thinning Processing Portion (634)
During prescanning, document input data is subjected to simple thinning for each 4 dots in the horizontal scanning direction, and the resulting data is output to marker color determination.LCD display image data coding processing portion 632.
(j) Texture Data Writing Portion (636)
During prescanning, the luminance signal (Y) of part of document input data (128×256 dots) is written into the texture memory.
(k) Color Determining Portion (638)
The color determining portion determines the colors of image data in the area designated by the editing area signal and outputs the determination information to substitute color data producing portion 640. The portion makes a prescribed determination for each function as color determination as follows.
Color change function: to determine whether an input image is of a designated document color and outputs the determination information to the substitute color data producing portion.
Texture function: to determine whether an input image is of a designated document color and the determination information is output to the substitute color data producing portion (designated color texture function).
Color determination portion 638 is provided with an ROM table for transforming color determination polar coordinates.
(1) Substitute Color Data Producing Portion (640)
The portion changes the colors of image data in an area designated by an editing area signal and outputs image data partly substituted by hemming editing instruction information. The substitute color data processing includes a prescribed conversion for each function as follows.
Color change function: a designated document color is changed to a designated substitute color (color region).
Texture function: a designated document color is changed into a texture memory data (color region).
Background color substitution function: a white region is changed into a region of a designated substitute color and a pattern (monochrome region).
Hemming function: the colors of an edge portion and an image inside the edge are changed into separate designated substitute colors (monochrome region).
(m) Area Signal Output Portion (642)
The area signal output portion changes an area signal designated by editing area memory 626 into an editing attribute signal to be output to the copying machine main body, and outputs an editing instruction signal to the hemming determination processing portion, color determination processing portion and substitute data producing portion. The attribute signal output to the copying machine main body is a monocolor/monochrome indication signal, negative/positive determination indication signal, or an image substitute/image erase/character combining indication signal.
(n) VRAM (616)
The VRAM is an image memory to store image data displayed on an LCD. Image data is written into the memory by the CPU. The image data within the memory is displayed on the LCD by the LCDC.
(o) LCDC (612)
The LCDC controls the LCD (VGA: 640×480/256 colors) and VRAM, and reads image data set in the VRAM for display on the LCD.
(p) CPU (602)
The CPU controls the display of LCD and produces editing area information.
(q) CPU Controller (610)
The CPU controller controls the address decoding and a bus when externally accessed. The controller controls input/output to/from the CPU through touch panel I/F.
(r) Program ROM (604)
The ROM stores programs for the CPU.
(s) Work RAM (606)
The RAM is for work/stack for the CPU.
(t) Backup SRAM (608)
The SRAM includes a built in battery to store backup parameters. The parameters are written by the CPU.
(u) Color LCD (115)
(v) Touch Panel (614)
Referring to FIG. 4, the copying machine main body includes an image reader 30, a copying machine processing portion 102 for converting a signal output from the image reader, an image processing portion 106 for processing a signal output from the copying machine processing portion 102, and a printer for printing an image corresponding to an output signal from the image processing portion.
Image reader 30 outputs 8 bit image data for each of Y, Cr and Cb. The output image data is input to the screen editor and copying machine processing portion 102. Copying machine processing portion 102 are provided with image data from image reader 30, 8 bit image data for each of Y, Cr and Cb output from the screen editor, and an editing area signal, and outputs processed image data.
FIG. 5 is a block diagram showing in detail the configuration of editing area designation memory 626.
The memory thins binary signals of 1 bit for black-and-white and 3 bits for colors (R, G, B, C, M, Y) to 100 dots for storing. The memory also functions as a closed loop.marker detection memory. The memory also stores an editing area based on designated coordinates input through the touch panel. The memory stores 16 kinds of editing area signals as bit map information.
Editing area designation memory 626 includes a DRAM 6262, a controller 6261 for the DRAM, a CPU data gate 6263, and the data gate 6264 of the editing area signal output portion. DRAM controller 6261 is provided with a CPU address, an area signal output portion address, a CPU read/write signal, and data from the area signal output portion. CPU data gate 6263 exchanges data with the CPU. Editing area output portion data gate 6264 outputs data to area signal output portion 642.
FIG. 6 is a diagram showing the planes of editing area designation memory. Referring to FIG. 6, the editing area designation memory is formed of 16 planes. One plane has a capacity of 2 Mbytes, and used to specify the position to edit in an input image data. The role of each plane in the editing area designation memory changes for each editing mode or each editing function.
FIG. 7 is a diagram showing how the memory planes of the editing area designation memory are allocated in each mode.
Referring to FIG. 7, the role of memory plane in each of bits 0 to 15 is described separately for the case of a black-and-white document, a color document, and black-and-white+color document.
Herein, the black-and-white document includes a document without coloring, and a black-and-white document having an area designated with a color marker by the user for the purpose of editing. The color document is a document such as a photograph. Black-and-white+color document is a document including both a black-and-white portion and a color portion.
Referring to FIG. 7, for a black-and-white document read, bit 0 is used as an erase area code. Herein, an image in a region designated by the erase area code is to be erased.
Bits 1 to 15 are used as the 1st to 15th character/base processing area codes. Thus, an editing processing corresponding to a region designated by each bit is executed.
If a color image document is input, bit 0 is used as an erase area code. Bit 1 is used as a negative/positive reversing area code. Bit 2 is used as a code for an area to be provided with patterns.
Bits 3 to 5 are used as first to third monochrome area codes to allocate first to third monochrome areas.
Bits 6 to 9 are used as first to fourth color change area codes to allocate first to fourth color change areas.
Bits 10 to 15 are used as first to sixth character/base processing area codes to allocate first to sixth character/base processing areas.
For a black-and-white+color document read, bits 0 and 1 are used as an image combining indication area. If the number indicated by bits 0 and 1 is "0", overlap combining is performed, for "1", fit in/character combining is performed, for "2", the image is erased, and for "3", no image is combined.
Bits 2 to 15 are used as area codes to allocate first to fourteenth fit in combining/character combining, editing within a black-and-white document and window designation areas.
Thus, the editing area designation memory is used in different ways based on the input image data.
Now, data stored in the editing area designation memory will be described by way of example.
Referring to FIG. 8A, the processing will be detailed when there are regions surrounded by a red marker (R), a green marker (G), and a blue marker (B) in part of a black-and-white document read by the image reader.
The document is read by image reader 30, binarized at binarizing processing portion 628 and stored in closed loop/marker detection/LCD display document memory 620.
At the time, in memory 620, as shown in FIG. 6B, data for only the black-and-white portion of the document is stored in a plane 201 to store black data.
Meanwhile, in a plane to store the marker color code of each of green and blue, as indicated by codes 202 to 204, only images in the portion corresponding to each marker color in the document are stored.
The document image stored in memory 620 is transferred to VRAM 616 through CPU 602, and then output to color LCD 115.
At the time, manually or by automatic setting with a device, whether to directly display the read document or to display an image after the image processing by the markers is selected.
More specifically, referring to FIG. 9A, if the mode to directly display the figures delineated by the markers is selected, the image the same as the read document image is stored in the VRAM as shown in image 205, and displayed on color LCD 115.
Meanwhile, the mode to display the effect of image processing by markers (the mode to display an image after image processing) is selected, based on the color of the marker as indicated by image 207 and its position, an image after image processing will be displayed. Note that the region surrounded by the red marker is hatched, the region surrounded by the green marker is colored, and a figure in the region surrounded by the blue marker has been reduced.
As image 205 is displayed, the user can mark with markers to the image being displayed through touch panel 614. For example, the user can additionally mark regions (1) and (2) to image 205 as in image 206 through touch panel 614.
More specifically, the user can know the states before and after image processing, make marking with markers for image processing through touch panel 614, which makes the machine easier to handle.
In editing area designation memory 626, data used for editing a black-and-white document is stored in each bit. More specifically, figures indicating editing regions set by marking with markers or input through the touch panel by the user are stored in the regions of bits 1 to 15.
Now, let us assume that an editing area as indicated by code 206 in FIG. 9A is set. Referring to FIG. 9B, the region surrounded by red marker (R) drawn in a black-and-white document is stored in bit 1 in area designation memory 626 in the state in which the inside the region is painted out. Note that the painted out position is stored with data of "1", and otherwise data of "0" is stored.
Similarly, the regions surrounded by green (G) and blue (B) being painted out are stored in bits 2 and 3, respectively in area designation memory 626.
The region of portion (1) input through the touch panel is stored in bit 4 in the area designation memory as being painted out, and the region (2) input through the touch panel is stored in bit 5 as being painted out.
Area signal output portion 642 recognizes the painted out regions stored in the memory, identifies these painted out regions to be regions for image processing, and outputs an editing area signal to copying machine processing portion 102.
FIG. 10 is a block diagram specifically showing the configuration of closed loop.marker detection memory/LCD display document memory 620.
Referring to FIG. 10, the memory stores color coding data for closed loop.marker determination data/LCD display which is produced by thinning document information to 100 dpi. The document information in the memory is transferred to the VRAM by the CPU and displayed on the LCD. In the black-and-white document mode, the closed loop.marker is detected by the CPU. The memory can be accessed by the CPU, the marker determination processing portion, and the LCD display color coding processing portion.
Referring to FIG. 10, memory 620 includes a DRAM 6201, a controller 6202 for the DRAM, a CPU data gate 6203, and a color code write/read data gate 6204.
DRAM controller 6202 is provided with a closed loop.marker/LCD display document address, a CPU write/read signal, and a write signal for the LCD display color coding processing portion.
CPU data gate 6203 exchanges data with the CPU. Color code WR data gate 6204 is provided with data from the LCD display color coding processing portion.
FIG. 11 is a diagram for use in illustration of the arrangement of planes in the closed loop.marker detection/LCD display document memory.
Referring to FIG. 11, there are eight layers of planes. The roles of these planes are different among different modes. FIG. 11 shows the arrangement of planes when an input document image is a black-and-white document image. Referring to FIG. 11, four planes are used for black-and-white gradation data for displaying the black-and-white document image on the LCD, and the other four planes are used as a memory for detecting closed loops and markers.
Meanwhile, for a color document or a black-and-white+color document, all the planes function as planes to store data for display on the LCD.
FIG. 12 is a diagram for use in illustration of how the role of a memory plane change depending upon the kind of a read document.
Referring to FIG. 12, as described above, for an input black-and-white document, memory planes of bits 4 to 7 are used for gradation data for displaying the black-and-white document, and bits 1-3 are used as codes for marker colors. The number "0" indicated by bits 1 to 3 represents a region without any marker, "1" a region in red, "2" a region in green, "3" a region in blue, "4" a region in cyan, "5", a region in magenta, and "6" a region in yellow.
The frame indicated by bit 0 is black-and-white binary data, and used to detect a closed loop present in the black-and-white document. Herein, the closed loop means a closed region delineated by a black line in the document. The user can designate the closed region by a marker or through type touch panel to color the region or hatch the region.
When an image in a read document is directly used as data to identify a closed loop, the line defining the closed loop may be sometimes disconnected depending on the characteristic of a CCD used and the closed loop may not be recognized successfully. As data in the plane of but 0, data produced by closing the line which defines the closed loop is stored. The closing processing will be described later.
Meanwhile, if a color document or a black-and-white+color document is input, data for display on the LCD is stored in bits 0 to 7 in all the memory planes. More specifically, one dot will be displayed by 8 bit data on the LCD. The input color document has its tonality lowered to the tonality which can be represented by the LCD display codes and stored in the memory.
Thus, the processing of switching the role of memory depending upon the content of an input document may be conducted by hardware, or maybe conducted by a flow as shown in FIG. 13.
Referring to FIG. 13, when the mode to process a black-and-white document is selected (YES in S1), the memory planes are allocated for the black-and-white document (S2). Meanwhile, the color document mode or the black-and-white+color document mode is set (YES in S3), the same memory planes for color are allocated (S4).
FIG. 14 is a block diagram showing in detail the configuration of binarizing processing portion 628.
In the configuration, a binarized document image is produced based on the luminance signal (Y) and color saturation signal (C) of document information and threshold parameters. The binarized document image is subject to 3×3 dots closing processing and stored in the binary memory.
Referring to FIG. 14, the block includes a threshold parameter output portion 6281 for outputting threshold parameters, a binarizing processing portion 6282 for binarizing an input document image, a control portion 6283 for controlling the binarizing processing, a widening processing 6284 for widening the binarized document image for closing, a narrowing processing portion 6284 for narrowing the thickened document image, an FIFO memory 6285 used for the thickening processing and an FIFO memory 6286 for the narrowing processing.
Binarizing processing portion 6283 is provided with the luminance signal (Y) and color saturation (C) of document information. Threshold parameter output portion 6281 is provided with a CPU address, data from the CPU and a write clock signal from the CPU.
Binarizing processing control portion 6283 is provided with a binarizing instruction signal, a binarized data writing instruction signal, a vertical scanning valid region, a horizontal scanning valid region, a horizontal scanning synchronizing signal, and a dot clock.
Narrowing processing portion 6287 outputs binary data after closing, and base determination data. Widening processing portion 6284 outputs binary data for detecting a closed loop.
Binarizing processing control portion 6283 outputs a clock signal, a write signal and an address clear signal to the binary memory.
Now, referring to FIG. 15, the closing processing will be detailed.
During the closing processing, if there is at least one black pixel among 3×3 pixels around a pixel of interest (the pixel hatched in FIG. 15), a pixel of interest is processed as a black pixel (thickening processing), and then if there is at least one white pixel among 3×3 pixels, a pixel of interest is processed as a white pixel (narrowing processing).
Thus, the line defining the contour of the closed loop will have no disconnected part, and the contour can be accurately determined when the inside the loop is colored.
FIG. 16 is a block diagram showing in detail the configuration of LCD display color coding/marker color determination processing portion 632.
The processing portion converts input color document image data into color codes for display on the LCD in the color document editing mode.
In the black-and-white document editing mode, the processing portion divides the data produced by thinning the document input data into six kinds of color data (R, G, B, C, Y, M).
Data after 3×3-dot closing processing is used as black data.
The processing portion thins document information at 1/4 in the vertical scanning direction, the document image will be stored in the LCD display document memory/closed loop dot marker detection memory for each 4 lines.
Referring to FIG. 16, processing portion 632 includes a determination portion 6323 for LCD display data coding/marker color determination based on input image data, an LCD display data coding/marker color determination processing control portion 6326 for controlling the determination, an output delay synchronizing control portion 6324, a bit 0 selector 6325 to output marker color/LCD display data, a closed loop.marker LCD display document memory writing control portion 6327, an ROM table 6321 for LCD display data coding/marker color determination, and an output delay FIFO memory 6322.
Now, a method of determining a marker color and a method of color coding a document will be described.
A marker color is determined by referring to the ROM table using input image data of V, Cr, and Cb thinned at 1/4 as ROM addresses. Black-and-white binary data is produced by thinning binary data for display output from the binarizing processing portion at 1/4 and output in synchronization with marker color determination data.
Document color coding is performed by referring to the ROM table using input image data of Y, Cr and Cb thinned at 1/4 as ROM addresses.
Now, the procedure of operating the copying machine shown in FIG. 1 will be described.
FIG. 17 is a flow chart for use in illustration of the procedure of operating the copying machine.
Referring to FIG. 17, the operator selects a desired menu among display editing menus (S10). Based on the content of the selected menu, a document is read and the read content is displayed on the screen editor (S11). The operator sets an editing content through the screen editor by viewing the content of the document displayed (S12). Then, a copy mode including the sheet size, the magnification and number of copies is set (S13). Then, an edited copy is output (S14).
FIG. 18 is a view showing examples of editing menus. The content shown in FIG. 18 are displayed on the LCD.
The menus include five purpose-specific editing menus, and a single registration menu.
In the coloring editing, characters or the base in a black-and-white document are colored.
In the marker editing, in a black-and-white document having an area designated by the marker pen, the area is colored.
In color editing, in a color document, various color editing processings such as color conversion, monochrome/color filtering are performed. The black-and-white portion of the color document may be colored.
In the trimming editing, part of a color or black-and-white document may be trimmed.
In the combining editing, a color document may be fit in a black-and-white document. In this editing, a black-and-white-document may be colored.
The registration refers to registration of a color palette or patterns as will be described.
The user can select a desired editing menu among them through the touch panel. Once a menu is selected, an image corresponding to each content will be displayed as shown in FIG. 19.
Now, an image when the coloring editing is selected is shown in FIG. 20. The user sets a black-and-white document to be colored according to the displayed message and presses a read key (lower right in the image). Then, the black-and-white document is read, and the image of the document is displayed on the LCD. In the state, the displayed document image is colored through the touch panel as shown in FIG. 21, and a colored copy is output from the printer.
In the coloring, an area designation tool as shown in FIG. 22 is used. The area designation tool includes an area select button to select a designated area, an entire document button for the entire document, a box button to designate a rectangular area, an R box button to designate a round rectangular area, a trace button to designate an area in a desired shape, a close loop button to designate an area in a closed loop, a linear button to draw a straight line, and a free shape button to draw a desired shape.
Herein, the box button is a button to designate a rectangle as an area to be colored and the rectangle is defined by two points, the starting point and ending point by dragging the pen.
The R box is a button to designate a square with its corners rounded off which is defined by two points, the starting point and ending point by dragging the pen. The round rectangle is shown in FIG. 23.
The trace button is a button to designate a closed free shape area with the starting point and ending point designated by dragging the pen. As a basic processing in the area designation by the trace button as shown in FIG. 24 at (A), an area surrounded by a trace line is extracted as a target area. If areas cross each other as shown in FIG. 24 at (A), the crossing area is extracted as a target area. In FIG. 24, the hatched region corresponds to a target area for processing.
The closed loop button is a button to designate an area closed in a black frame around the position input by the pen as a target area. The closed loop area processing proceeds as shown in FIG. 25.
More specifically, as a basic processing, the area surrounded by the black frame is extracted as a closed loop area (FIG. 25(A)). If there is another closed loop in a closed loop, the area surrounded by the outer black frame is extracted as a closed loop area (FIG. 25(B)). The inner closed loop area is not recognized. Thus, closed loops present in alphabet "B" for example is not identified.
If a portion outside the closed loop is designated, the area is not recognized as a closed loop area (FIG. 25 (C)).
FIG. 26 shows an image when the marker editing mode is designated.
Referring to FIG. 26, the operator sets a marker-processed black-and-white document to IR, presses the read key according to the displayed content shown in FIG. 26, and the marker document is read. The read marker document is displayed on the LCD as shown in FIG. 27. The marker designation is made by designating an area desired to be edited with a marker (surrounding frame designation) or by designating an area within a closed loop by marking dots with a marker within a closed loop of the document (dot designation).
A further marker area may be designated to a document displayed on the LCD, in which case the marker area designation tool shown in FIG. 28 is used. The marker area designation tool can designate yellow, magenta, cyan, green, red and blue, and the surrounding frame designation and dot designation can be made for each color.
FIG. 29 shows an image when the color editing mode is designated. The operator sets a color document or a color+black-and-white mixture document to process at the IR according to the message displayed in the image and presses the read key. Thus, the color document is read, and displayed on the LCD as shown in FIG. 30. The user designates color conversion, for example, through the touch panel to the color document.
In FIG. 18, if the registration mode is selected, the image shown in FIG. 31 is displayed on the LCD.
There are four kinds of registration menus. In the color palette editing, colors are registered, the standard color palette, and colors to register are read. In the pattern editing, the pattern editing is made for coloring the background. In the texture registration, the texture pattern is read for registration. In the marker editing setting, a standard (default) editing mode for marker editing is set. As shown in FIG. 32, an image corresponding to the content of each button pressed by the operator is displayed for registration.
FIG. 33 is a flow chart for use in illustration of the processing of displaying images for operating the digital color copying machine according to this embodiment. FIG. 34 is the continuation of the flow chart shown in FIG. 33.
Referring to FIG. 33, once the machine is activated, in step S100, the editing menu image shown in FIG. 18 is displayed. In step S101, the process is branched depending on a mode selected by the user.
If "registration" is selected, the registration menu as shown in FIG. 31 is displayed in step S102, and various setting images are displayed according to the user's selection for registration as shown in FIG. 32. In step S103, it is determined whether there has been a key input, and the processing from step S100 is once again executed if the answer is YES.
Meanwhile if "coloring editing" is selected, the image shown in FIG. 20 is displayed in step S104, and reading of a document to be colored is initiated. In step S105, it is determined if the reading of the document has been completed, if the answer is YES, the editing image shown in FIG. 21 is displayed in step S106, and the user performs an editing processing. After the editing processing, it is determined in step S107 if the print key has been turned on, and if the answer is YES, a printing processing is executed in step S108. It is determined in step S109 if the printing processing has been completed, and if the answer is YES, the processing from step S100 is once again executed.
In the mode selecting image, if "marker editing" is selected, the image shown in FIG. 26 is displayed in step S110, and reading of a black-and-white document processed with markers is initiated. It is determined in step S111 if the reading of the document has been completed, if the answer is YES, the editing image shown in FIG. 27 is displayed in step S112, and an editing processing by the user is performed. It is determined in step S113 if the print key has been turned on after the editing processing, and if the answer is YES, the printing processing is executed in step S114. Then, it is determined in step S115 if the printing processing has been completed, and if the answer is YES, the processing from step S100 is once again executed.
In the editing menu, if "color editing" is selected, the image shown in FIG. 29 is displayed in step S116, and a color document is to be read. It is determined in step S117 if the reading of the document has been completed, if the answer is YES, the editing image shown in FIG. 30 is displayed in step S118, and an editing processing corresponding to the input by the user is executed. It is determined in step S119 if the print key has been turned on after the editing processing, and if the answer is YES, a printing processing is executed in step S120. It is determined in step S121 if the printing processing has been completed, and if the answer is YES, the processing from step S100 is once again executed.
In the editing menu, if "trimming" is selected, a document to be trimmed is read in step S122. It is determined in step S123 if the reading of the document has been completed, and if the answer is YES, a trimming processing corresponding to the input by the user is executed in step S124.
It is then determined in step S125 if the print key has been turned on, and if the answer is YES, the printing processing is executed in step S126. It is determined in step S127 if the printing processing has been determined, and if the answer is YES, the processing from step S100 is once again executed. In the editing menu, if "combining" is selected, documents to be combined are read in step S128. It is then determined in step S129 if the reading of the documents has been completed, and if the answer is YES, a combining processing corresponding to the input by the user is executed in step S130.
It is then in step S131 if the print key has been turned on, and if the answer is YES, the printing processing is executed in step S132. It is determined if the printing processing has been completed in step S133, and if the answer is YES, the processing from step S100 is again performed.
As in the foregoing, in the copying machine according to this embodiment, the operator can confirm the result of editing before outputting a copy, copying fault may be reduced, thus making the machine easier to use.
In addition, data which has gone through the closing processing may be used for detecting closed loop, and therefore, close loops may be more accurately detected. An image as read without any such closing processing can be displayed LCD if desired, and therefore the image suitable for the operator to view can be displayed on the LCD.
Furthermore, depending on the reading mode (black-and-white document/color document), the memory plans of the LCD display memory are used in different ways, a document read at the most preferable image quality for an image to be read can be displayed.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
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An image editing apparatus reads a document image and obtains image data. Thus obtained image data is separately stored as data to be displayed on a display and data for recognizing a closed region in the image. In order to more readily recognize such a closed region, only the latter data is processed without changing the data to be displayed on the display. Thus, an image much easier to view can be displayed on the display.
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BACKGROUND OF THE INVENTION
The present invention relates to a type of steam distributor known as a "steambox" which is used in the manufacture of sheet materials, and in particular, to a steambox design that increases the production rate of paper sheet while decreasing energy utilization. Even more particularly, the present invention relates to a steambox design which substantially eliminates undesirable dripping of condensation onto the paper sheet from the steambox itself and from adjacent structures.
One of the parameters used in grading sheet materials is the moisture content of the material. For example, in the paper production process, various grades of paper having different moisture contents are produced to suit various applications.
Paper production begins with a wet mass of fibers and typically involves several drying processes, the first of which includes impinging the paper sheet material with steam from a steambox and may also include drawing the steam through the sheet with a vacuum box to improve heat transfer from the steam to the sheet. This steam treatment, for example, may cause an increase in sheet temperature of approximately 30° C. The increased temperature decreases the viscosity of water in the sheet. At a later point in the papermaking process, water is squeezed and/or suctioned out of the paper sheet in a section of the papermaking machinery known as the "press section". Because the steam heats the water, the water viscosity is decreased, and thus the pressing and suctioning of water out of the sheet is rendered more effective. In still later drying steps, the sheet is typically passed over several heated steel drums, in the so-called "drying section" of the papermaking machine, to further reduce the moisture content of the sheet. The resulting increase in the dryness of the sheet as it leaves the press section permits an increase in the sheet production rate, as drier paper can move more rapidly through the subsequent drying section.
In the production of many paper products, it is desirable to automatically control the "cross-directional" (i.e., the direction across the width of the sheet perpendicular to the direction of sheet movement) moisture content of the paper sheet using a steambox. Many papermaking machines have scanning moisture sensors which continuously scan back and forth across the width of the sheet and sense the sheet moisture content at various locations across the sheet as the paper is manufactured. The information from this continuous moisture measurement can be fed into a controlling computer. The computer then controls the amount of steam applied by the steambox to various locations across the width of the sheet based upon the sensed moisture content.
Examples of steam distributors are shown in U.S. Pat. Nos. 4,253,247 and 4,580,355, which are incorporated herein by reference. These patents teach a multi-chambered steam distributor in which steam flows from a steam pipe through a valve associated with each chamber, into each chamber, and then is directed to the section of the sheet adjacent to each chamber. The steam flow out of each chamber and toward an adjacent sheet section is controlled by progressively opening or closing the associated valve.
FIG. 1 illustrates an example of a known process in which the present invention may be applied. In particular, FIG. 1 shows a papermaking machine including a steambox 10 to assist in drying the sheet 8. The papermaking machine shown is of the Fourdrinier type and includes a head box 2 feeding a pulp and water mixture 4 to a porous conveyer belt called a "wire" 6 through which the water is drained from the pulp. The paper sheet 8 travels under the steambox 10 and over a vacuum box 12, which, as previously mentioned, assists in drawing the steam through the sheet 8. FIG. 1 also shows an alternate position "A" where the steambox 10 may also be located.
After passing under the steambox 10, the sheet then passes through the press section 14, including pressure rollers 15 and absorbent material 17, further dryers (not shown) and a known scanning moisture sensor 16 which, as previously mentioned, measures the moisture content of the sheet at various locations across the width of the sheet 8. The amount of steam jetted from the steambox 10 at various cross-directional locations is adjusted manually or automatically to reduce the moisture variations in the cross-direction of the sheet 8. As more steam is jetted from a particular steambox chamber onto an opposing section of the sheet, that sheet section becomes hotter and the water viscosity in that sheet section decreases; therefore, the more effectively water may be removed from the hot sheet section. In other words, the use of more steam results in a drier sheet section.
A common problem encountered in altering the moisture content of the sheet via steam treatment is that excess steam that has not been absorbed by the sheet may condense on cool surfaces of the adjacent structures of the paper processing machinery and then drip onto the sheet. The sheet thus moistened will then bear an unsightly water mark. Moreover, this wet portion is weaker than the rest of the sheet and is therefore unusually subject to tearing.
Another shortcoming of the prior art is the use of diffusion plates, which generally contain a large number of small openings through which steam is jetted from the steambox onto the paper sheet. When steam is ejected through these numerous openings, especially numerous small openings, the large quantity of surface area of the steam entrains a relatively large volume of ambient air, which cools the steam before it contacts the sheet; thus, the sheet is not heated as efficiently or as much, and condensation is more likely to occur.
In addition, to the best of applicant's knowledge, the prior art fails to address or remedy the problem of condensation formation within the steambox itself; this condensate could easily drip out of the openings in the diffusion plate and onto the sheet. Such an occurence is particularly troublesome when the machinery is first started up and the steambox is cold.
To overcome the shortcomings of the prior art, it will be appreciated that it is desirable to apply steam to a paper sheet in a manner that will increase the temperature of the sheet while producing a resultant decrease in the viscosity of the water contained in said sheet; this combination of increased heat and decreased viscosity will greatly facilitate immediate and subsequent removal of water from the sheet via a pressing and/or a suctioning process. It will also be appreciated that a steam treatment method that reduces the amount of condensation on the equipment in close proximity to the sheet and that eliminates dripping of water from inside the steambox will reduce the possibility of tearing the sheet, and will also reduce unsightly water marks.
SUMMARY OF THE INVENTION
The present invention is directed toward a steambox designed for efficient steam heating of a paper sheet while reducing or eliminating drippage from the steambox, condensation of steam upon adjacent surfaces of the papermaking machine, and upon the steambox itself.
The steambox includes an elongated steam plenum which preferably, but not necessarily, extends across the entire width of a sheet which is moving through the papermaking machine. One wall of the plenum is disposed in close facing proximity to the moving sheet. A single cross-directionally oriented steam exit slot is formed in this wall for directing steam from the steambox toward the sheet.
The interior of the plenum is divided into chambers, each of which extends across less than the entire width of the sheet. A steam valve is associated with each chamber for selectively controlling the flow of steam from a steam supply pipe into each steam chamber and subsequently out of the slot toward the sheet.
Use of a single steam slot increases the heating efficency of the steam, as the steam ejected from the single slot entrains less ambient air (and thus cools less rapidly) than the same volume of steam ejected from numerous smaller openings. Further, this increased heating efficiency results in the formation of less condensate, as the surface of the steambox adjacent the sheet and the paper sheet itself are hotter. By opening and closing the steam valve associated with any selected chamber, more or less steam can be directed through the slot at the cross-directional sheet section adjacent to the selected chamber.
Another significant improvement over the prior art consists of the use of "dam walls" positioned inside the plenum at the anterior and posterior sides of the steam exit slot. The dam walls prevent water which has condensed inside the plenum chamber from dripping out of the exit slot and onto the sheet. Drainage holes positioned on both sides of the steam exit slot allow the condensate to be drained away from inside the plenum and thus function to prevent the leakage of condensate from the slot onto the paper sheet.
The moisture content of the sheet may be monitored and compared to a desired moisture content, and the steam valves are activiated accordingly. For example, a known type of moisture sensor may be positioned at a location downstream of the steambox on the papermaking machine. The moisture sensor is scanned back and forth across the width of the sheet and generates signals indicative of the sheet moisture content at various locations across the sheet. The moisture signals are then transmitted to a computer. The computer is programmed to selectively open and close the steam valves assocated with each chamber to achieve the desired sheet moisture content. For example, if a sheet section is too moist, the computer will open the valve associated with the chamber disposed over the moist sheet section. Conversely, if a sheet section is too dry, then the computer will close the steam valve associated with the chamber over the dry sheet section. Depending upon the amount of excess moisture in the sheet sections or the dryness of the sheet sections, the valves can be completely opened or closed, or partially opened or closed to achieve the desired sheet moisture profile.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a paper-making machine including a steambox which may be designed according to the present invention, and suggested locations for same;
FIG. 2 is a perspective view of one presently preferred embodiment of a steambox according to the present invention; and
FIG. 3 is a cross-sectional illustration of the embodiment shown in FIG. 2 taken along line 3--3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The following description is of the best presently contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
FIGS. 2-3 illustrate a presently preferred embodiment of the steambox 10 of the present invention. In this embodiment, the steambox 10 is lined with insulation 40 on various interior surfaces to increase the heating efficiency of the steambox 10 by retarding the loss of heat though all of the external walls of the steam plenum 31, except the wall 24 which directly opposes the sheet 8. The steambox plenum 31 is divided, for example, at 6 inch intervals along the cross-direction into steam chambers 32; steam enters these chambers 32 via steam valves 42 and headers 44. Details of the valves 42 are not taught herein and can be ascertained from U.S. Pat. No. 4,580,355, incorporated herein by reference. Other known types of valves are also suitable. One steam valve 42 controls the flow of steam into each associated chamber 32.
One aspect of the preferred embodiment of the invention is a single steam exit slot 46 which extends in the cross-direction across the lower wall 24 of the steambox 10, said wall 24 facing a paper sheet 8 in a papermaking machine, such as the example illustrated in FIG. 1. For the purpose of clarity, this wall 24 shall be referred to as the "face plate" 24. All external walls of the steambox are insulated, but not the face plate 24. The advantages of utilizing a non-insulated face plate 24 with a single, cross-directionally oriented steam exit slot 46 include the following. First, as previously mentioned, if steam is ejected through a single opening, as opposed to several small ones, the surface area of the steam exposed to ambient air is much less than that exposed when numerous openings are used to jet an equivalent volume of steam into a sheet. As a result, steam ejected from the slot 46 entrains less ambient air, does not cool down as rapidly and is therefore more effective at heating the sheet. Second, the lack of insulation on the inside surface of this face plate 24 permits the steam inside the plenum to keep this face plate hot. The hot face plate 24 produces less condensation thereupon. Third, use of a single slot 46 reduces the number of openings on the face plate 24 from which condensate could drip from the plenum 31 onto the sheet 8. Fourth, in the manufacture of the slot 46 in the face plate 24, the sheet metal forming the face plate 24 can be bent into the interior of the plenum. The bent portions, called "dams" 64, prevent steam which has condensed inside the plenum 31 from dripping out of the plenum 32 and onto the sheet 8. The use of a single slot 46 also results in simpler and far less expensive construction than would be required if numerous small holes with surrounding dams were fabricated.
A second component of the invention is a structure 48 angled atop the steam exit slot 46, which structure functions to deflect drippage from within the plenum 31 and keep the drops from exiting the slot 46. In the illustrated embodiment, this angled structure 48 (the "umbrella") is integrally formed with the posterior of a dam wall 64 inside the plenum chamber 32. While the umbrella 48 does not close off the slot 46 or obstruct the ejection of steam therefrom, the umbrella 48 does prevent condensed steam on the interior surfaces of the plenum 31 from dripping onto the paper sheet 8. The angle of the umbrella 48 may be adjusted to conform to the particular needs or requirements of a manufacturing process, provided the umbrella 48 inhibits dripping onto the sheet 8. In particular, as shown in FIG. 3, the umbrella 48 within the plenum chamber 32 should be angled away from the nozzle 60 to thereby shield the steam exit slot 46 from water drops ejected from the nozzle 60.
A third component of the invention is a system of drains 50 located anteriorly and posteriorly to the steam exit slot 46 within the plenum chambers 32. These drains 50 function to capture and remove condensation that forms within the plenum chambers 32. Thus, the drains 50, working in tandem with the dams 64 and umbrella 48, greatly reduce or completely prevent the drippage of condensate from within the chambers 32 onto the paper sheet 8. The drains illustrated in FIGS. 2-3 are simply circular holes cut in the sheet metal walls dividing the steam plenum 31 into various chambers 32. Tubing 33 is provided in the exterior side walls of the plenum 31 to allow the condensate to be drained away to a suitable location.
To further improve the effectiveness of the invention and to prevent condensation of excess steam on structures adjacent to the steam treatment zone defined by the face plate 24 of the steambox 10 and the paper surface 8, as condensation would otherwise adversely affect the papermaking process, a suction device may also be provided as part of the inventive steambox 10 to remove excess steam which would otherwise escape from the steam treatment zone.
As shown in FIG. 3, a vacuum plenum 52 may be provided within the steambox 10, separated from the steam chambers 32 by an insulated wall 62. The vacuum plenum 52 shown has an opening 54 at the trailing edge 56 of the steambox 10 and the opening 54 is in the form of a single slot 54 spanning the entire cross-direction of the face plate 24, as shown in FIGS. 2 and 3. This slot is known as a "scavenger" slot 54. Excess steam that has reached the trailing edge 56 of the steambox 10 is sucked into the vacuum plenum 52 via the scavenger slot 54 and out of the steambox 10 through a vacuum or exhaust pipe 28. The vacuum suction confines the steam within the steam treatment zone to prevent undesirable condensation of excess steam on adjacent surfaces. In addition, the vacuum suction facilitates the flow of steam from the steam exit slot 46 toward the trailing edge 56 of the steambox 10, as the steam deflects back and forth between the paper surface 8 and the face plate 24 as the paper moves along in the direction of arrow 70 (FIG. 3).
As the steam travels along the face plate 24, any condensation on the exterior surface of the face plate 24 may also be sucked into the vacuum plenum 52. The suction through the scavenger slot 54 diverts steam away from adjacent surfaces of the papermaking machine which otherwise would condense on those surfaces. To facilitate the flow of steam out of the vacuum plenum 52, the steam is maintained in a gaseous state in the vacuum plenum 52 by minimizing heat loss through the external walls of the plenum 52. Insulation material 40, such as fiberglass, is applied to the inside of the walls of the vacuum plenum 52. In addition, any condensation that forms within the vacuum plenum 52 is captured by drains 58 on both sides of the scavenger slot 54. The scavenger slot 54 is also bounded by dam walls 64 and an umbrella 48 to prevent drippage onto the sheet 8 of any steam which may condense inside the vacuum plenum 52.
In operation, steam fills each chamber 32, heating the face plate 24, exiting the steam slot 46 and impinging upon the paper sheet 8, as illustrated by the arrows in FIG. 3. The portion of the steam not immediately absorbed by the paper is deflected back and forth between the paper surface 8 and the face plate 24 (arrows 25) as the steam moves downstream in the direction of the paper movement. Each time the steam hits the paper surface 8, some steam is absorbed by the paper. Thus, the steam discharged through the steam exit slot 46 is able to treat a large area of the paper surface. As shown, the steam chambers 32 are located just inside of the face plate 24, so that the face plate 24 forms the external wall of each chamber 32. In this configuration, the steam in the chambers 32 keeps the face plate 24 hot to prevent condensation of the steam on the face plate 24.
It can be seen that by means of the plurality of valves 42 spaced at intervals in each chamber 32 across the span of the steambox 10, the amount of steam applied to the paper surface 8 may be controlled to vary by a desired amount in the cross-direction. A desired steam distribution profile in the cross-direction may be achieved by selectively controlling each steam valve 42 assocated with each chamber 32. Consequently, since the moisture content of the paper may be altered by the amount of steam applied to the paper surface 8, the moisture content of each section of the paper surface corresponding to each chamber 32 of the steambox 10 in the cross-direction may be controlled by supplying the appropriate amount of steam through the valves 42. Note, however, that it does not necessarily follow that, when different amounts of steam are supplied to the different chambers and hence to different sections of the paper surface, the moisture profile in the cross-direction will not be uniform. In a situation where a uniform moisture profile in the cross-direction is desired, it may be necessary to discharge different amounts of steam through each valve 42 in order to compensate for other variables in the papermaking system.
It is apparent that by increasing the number of chambers 32 and associated steam valves 42, that is, increasing the number of corresponding sections of the paper surface in the cross-direction by decreasing the size of each chamber 32, the resolution of the control of the moisture profile may be improved.
As shown in FIG. 1, a computer 18 may be employed to maintain a uniform moisture content or a predetermined moisture content in the paper sheet 8 by controlling the valves 42 (shown in FIG. 3) based upon the signals from the moisture sensor 16. The computer 18 receives signals from the moisture sensor 16 and can then compare the moisture content of the sheet to a desired moisture content. Based upon the determined deviation in the measured moisture content of the paper sheet 8 from the desired moisture content, the computer 18 will then selectively transmit control signals to the steam valve actuators 66 adjust (shown in FIG. 3) in the steambox 10 which in turn adjust the associated steam valves 42 so that the valves 42 discharge more or less steam through the nozzles 60 so as to provide the desired moisture profile.
Typically, if the moisture sensor 16 detects a higher moisture content than desired in a section of the paper sheet 8, the computer 18 adjusts the valve 42 in the chamber 32 adjacent to that sheet section and allows more steam to be applied to that section. As a result, the moisture content of that section of the paper sheet 8 is reduced because the temperature of that section is increased. As previously explained, the increased temperature decreases the viscosity of the water in that section. The hotter, less viscous water is more effectively removed from the sheet and the sheet section is therefore relatively drier. Alternatively, when the moisture sensor 16 detects a lower moisture content than desired in a particular sheet section, less steam is applied to that section.
In summary, the present invention provides a steambox for controllng the moisture profile across a sheet by selectively directing varying amounts of steam against cross-directional sections of the sheet. The design has a high heating efficiency resulting from the use of a single, cross-directional steam exit slot. Also, the amount of drippage from the apparatus is reduced or eliminated through the use of dams and umbrellas for preventing condensation inside the plenum from dripping onto the sheet and drains for draining away condensate from inside the steambox plenum 31.
One preferred embodiment of the present invention has been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the overall shape of the steambox need not be precisely rectangular; i.e., the face plate may be angled or curved instead of straight across so as to best conform to the shape of the adjacent sheet surface. Also, a working fluid other than steam may be employed without departing from the principles of the present invention. Moreover, the invention is not limited to use with paper. The invention may be used with other materials. Furthermore, it is expecially preferred to use a single steam exit slot since, as explained above, this will result in a minimal amount of entrained air and more efficient construction. However, the use of a limited number of slots is also within the scope of the invention, since a limited number of slots will result in less entrained air than the large number of holes used in prior art diffuser plates, though to a lesser extent than a single slot. For example, in certain circumstances it may be convenient to form one cross-directionally elongated slot for each steam chamber. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiment, but only by the scope of the appended claims.
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The specification discloses a steambox for assisting in the drying of sheet material. The steambox has a means for preventing steam which condenses inside the steambox plenum from dripping onto the sheet. The steam is jetted from the plenum toward the sheet through a single cross-directionally oriented slot to decrease entrainment of ambient air and thereby increase heating efficiency.
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FIELD OF THE INVENTION
[0001] This invention relates to semiconductor device structures with improved packing/cell density and breakdown, and in particular MOSFETs having a gate electrode located in a trench, more specifically a low-voltage trench-gated power MOSFET having an improved breakdown characteristic, a thin gate oxide to reduce the gate drive voltage, and a high cell density to lower the on-resistance of the MOSFET.
BACKGROUND OF THE INVENTION
[0002] MOSFETs have become the preferred devices for switching currents in numerous fields, including the computer and automotive industries. Three of the principal characteristics of MOSFETs are their gate drive voltage, their on-resistance (R ds -on) and their avalanche breakdown voltage (V B ). The gate drive voltage is determined primarily by the gate oxide thickness; the thinner the gate oxide, the lower the gate drive voltage. However, a thinner gate oxide leads to a lower breakdown voltage, especially for trench power MOSFETs. The breakdown voltage is normally provided largely by a lightly-doped “drift” region that is located between the drain and body regions of the MOSFET. For example, in MOSFET 10 shown in FIG. 1 , a lightly-doped N-epitaxial (epi) layer 104 is grown on a heavily-doped N+ substrate 102 , which serves as the drain of the device. (Note that FIG. 1 is not drawn to scale; for example, substrate 102 would typically be much thicker than epi layer 104 .) A trench is formed in the top surface of epi layer 104 , frequently using a reactive ion etch (RIE) process. The walls of the trench are lined with a gate oxide layer 112 , and the trench is filled with a conductive material, often doped polycrystalline silicon (polysilicon), which serves as a gate electrode 110 . The top portion of the epi layer 104 is implanted with a P-type impurity such as boron to form a P-body region 108 , and using appropriate photoresist masks, N and P type dopants are implanted and diffused to form N+ source regions 110 and P+ body contact regions 118 at the surface of epi layer 104 . The implantations used to form P-body region 108 , N+ source regions 110 and P+ body contact region 118 are frequently performed before the trench is etched.
[0003] A borophosphosilicate layer 116 is deposited and patterned so that it covers and isolates the gate electrode 110 , and a metal layer 114 is deposited over the top surface of the device. Metal layer 114 , which can be an aluminum or copper alloy, makes an ohmic electrical contact with N+ source regions 110 and P+ body contact regions 118 .
[0004] Current flows vertically through MOSFT 10 from the N+ drain 102 and through an N-drift region 106 and a channel region (denoted by the dashed lines) in P-body region 108 to the N+ source regions 110 .
[0005] The trench is typically made in the form of a lattice that creates a number of MOSFET cells. In a “closed cell” arrangement, the MOSFET cells may be hexagonal, square or circular. In an “open cell” arrangement, the cells are in the form of parallel longintudinal stripes.
[0006] When MOSFET 10 is reverse-biased, the N+ drain region 102 is biased positively with respect to the N+ source regions 110 . In this situation, the reverse bias voltage appears mainly across the PN junction 120 that separates N-drift region 106 and P-body region 108 . N-drift region 106 becomes more and more depleted as the reverse bias voltage increases. When the depletion spreading reaches the boundary between N+ substrate 102 and N-drift region 106 , any further increases in the reverse bias are seen at PN junction 120 . Thus making N-drift region 106 thicker generally provides greater protection against breakdown. Furthermore, there is a generally inverse relationship between the avalanche breakdown voltage of PN junction 120 and the doping concentration of N-drift region 106 , i.e, the lower the doping concentration of N-drift region 106 , the higher the breakdown voltage V B of PN junction 120 . See Sze, Physics of Semiconductor Devices, 2 nd Ed., page 101, FIG. 26 , which provides a graph showing the relationship between the doping concentration and V B for several semiconductor materials.
[0007] Thus, to increase the breakdown voltage of junction 120 , one would like to reduce the doping concentration of N-drift region 106 . This in turn, however, reduces the quantity of charge in N-drift region 106 and accelerates the effect of depletion spreading. One solution would be to increase the thickness of N-drift region 106 , but this tends to increase the on-resistance of MOSFET 10 .
[0008] U.S. Pat. No. 5,216,275 describes a high voltage drift structure useful for trench power MOSFETs, diodes, and bipolar transistors. The drift structure includes a “composite buffer layer” that contains alternately arranged areas of opposite conductivity.
[0009] In low voltage and high density trench MOSFETs there is another limitation. A high field at the bottom of the gate oxide, which limits the breakdown voltage and the oxide thickness. U.S. Pat. No. 5,168,331 proposes a floating, a lightly doped P-region just below the trench gate oxide to reduce the field which it does. However, P-shield region (e.g., boron atoms) out diffuse towards the P-body, which increases Rds on and /or requires the packing density to be reduced.
[0010] The present invention overcomes these problems.
SUMMARY OF THE INVENTION
[0011] A trench-gated semiconductor device according to this invention includes a semiconductor substrate of a first conductivity type. An epitaxial layer is formed on the substrate. First and second trenches are formed in the epitaxial layer, the first and second trenches being separated by a mesa. Each of the trenches comprises a gate dielectric layer, the gate dielectric layer lining the walls and floor of the trench, and a gate electrode bounded by the gate dielectric layer. A body region of a second conductivity type is located in the mesa. A source region of the first conductivity type is located adjacent a wall of the trench and the top surface of the epitaxial layer. A drift region of the epitaxial layer is located below the body region and doped with material of the first conductivity type. A field shield region of the second conductivity type is located below each of the trenches, the sides of the field shield region being bounded by dielectric sidewall spacers. The dielectric sidewall spacers separate the field shield region from the drift region of the epitaxial layer. A metal layer lies on top of the epitaxial layer and is in electrical contact with the source region and the body region. The field shield region is electrically connected to the source region and the body region.
[0012] With this structure, depletion regions form on both sides of dielectric sidewall spacers when the MOSFET is in an off condition and blocking a voltage. This increases the avalanche breakdown voltage of the device and allows the drift region to be doped more heavily, reducing the on-resistance of the MOSFET. The dielectric spacers bordering the field shield region confine the field shield region to the area directly beneath the trench floor. Use of the field shield region decouples the gate oxide thickness from the breakdown voltage of the device.
[0013] As a result, the cell packing density can be increased, and the gate oxide thickness can be reduced to achieve a threshold voltage as low as 1V Vgs while maintaining a high breakdown voltage.
[0014] This invention also includes a process for fabricating a trench-gated semiconductor device. The process includes providing a semiconductor substrate of a first conductivity type; forming an epitaxial layer of the first conductivity type on the substrate; forming first and second trenches in the epitaxial layer, the first and second trenches being separated by a mesa; forming dielectric sidewall spacers on the walls of the trenches; forming a “field shield region” on the bottom of the trench by partially filling the trench with a semiconductor material of a second conductivity type; removing portions of the dielectric sidewall spacers above the field shield region; forming a dielectric layer on the walls of the trenches above the field shield region and on the top surface of the field shield region; and filling an upper portion of the trenches with a conductive gate material.
[0015] In one variation of the process, source regions are formed in the mesa by forming a first dielectric layer above the conductive gate material, depositing a layer of polysilicon containing a dopant of the first conductivity type on the entire top surface of the structure and directionally etching the layer of polysilicon to leave a polysilicon spacer adjacent a vertical surface of the first dielectric layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a cross-sectional view of a conventional trench-gated MOSFET.
[0017] FIG. 2A is a cross-sectional view of a MOSFET/IGBT which includes a field shield region in accordance with this invention.
[0018] FIG. 2B is a cross-sectional view of a semiconductor device containing a generalized field shield region in accordance with this invention.
[0019] FIG. 2C is a cross-sectional view of a Schottky barrier diode containing a field shield region in accordance with this invention.
[0020] FIG. 2D is a cross-sectional view of a vertical JFET device containing a field shield region in accordance with this invention.
[0021] FIGS. 3A and 3B illustrate techniques for establishing electrical contact between the field shield regions and the source regions in the MOSFET shown in FIG. 2 .
[0022] FIGS. 4A-4H illustrate a process sequence for fabricating the MOSFET/IGBT shown in FIG. 2A
[0023] FIGS. 5A-5G illustrate a process sequence for fabricating an alternative embodiment of the invention.
[0024] FIG. 6 illustrates a variation of the MOSFET shown in FIG. 5G .
[0025] FIG. 7 shows another alternative embodiment of a MOSFET in accordance with this invention.
[0026] FIGS. 8A-8C illustrate a process for forming the field shield contact shown in FIG. 3B when the process shown in FIGS. 4A-4H is used to manufacture the MOSFET.
[0027] FIG. 9 illustrates an alternative process for forming the field shield contact shown in FIG. 3B when the process shown in FIGS. 5A-5G is used to manufacture the MOSFET.
[0028] FIG. 10 illustrates a preferred structure of the termination region when the structure of FIG. 3A is used to contact the field shield region.
[0029] FIG. 11 illustrates a high-voltage termination structure that can be fabricated with three-mask process shown in FIGS. 5A-5G .
[0030] FIGS. 12A and 12B illustrate a preferred structure for contacting the gate of the MOSFET when the MOSFET is manufactured using the process shown in FIGS. 4A-4H .
[0031] FIGS. 13A and 13B illustrate a preferred structure for contacting the gate of the MOSFET when the MOSFET is manufactured using the process shown in FIGS. 5A-5G .
[0032] FIGS. 14A-14C illustrate portions of stripe (open cell), square and hexagonal patterns in which the trenches and mesas can be formed in devices according to this invention.
DESCRIPTION OF THE INVENTION
[0033] FIG. 2A shows a MOSFET 30 in accordance with this invention. MOSFET 30 is formed on an N+ substrate 302 and an overlying epi layer 304 . Trenches 306 are formed in epi layer 304 , and trenches 306 are lined with a gate oxide (SiO 2 ) layer 310 and filled with a gate 308 . Alternatively, layer 310 could be formed of silicon nitride (Si 3 N 4 ). Gate 308 is typically formed of heavily-doped polysilicon and can include a silicide.
[0034] A mesa between trenches 306 includes a P-body region 316 . Within P-body region 316 are N+ source regions 312 and a P+ body contact region 314 . The top surface of gate 308 is covered with a BPSG layer 324 . A source metal layer 326 overlies BPSG layer 324 and makes electrical contact with N+ source regions 312 and P+ body contact regions 314 . Similarly, a metal layer 325 contacts N+ substrate 302 , which functions as the drain. The electrical contact between metal layer 325 and N+ substrate 302 could be ohmic or could include a Schottky barrier.
[0035] The remaining portion of epi layer 304 is divided into N drift region 318 and P field shield regions 320 . Each of P field shield regions 320 is located below one of trenches 306 and is separated laterally from N drift region 318 by oxide sidewall spacers 322 . In some embodiments, field shield regions 320 could extend downward to N+ substrate 302 .
[0036] FIG. 2A illustrates the present innovation in a “U ” shaped trench gate device. However the basic “field shield region” bounded by dielectric sidewalls only or by dielectric sidewalls and a dielectric top wall is applicable to devices of many shapes, including devices having gates in U-shaped or V-shaped grooves and planar structures.
[0037] A key innovation in FIG. 2A is the structure below the trench gate; the P-field shield region 320 is laterally bounded by dielectric sidewalls 322 and bounded on the bottom by the PN junction with by N-region 318 . This more general structure is illustrated in FIG. 2B . As shown in FIG. 2B , P-field shield region 320 may be electrically biased either by shorting P-field shield region 320 to the top surface electrode of the N-region, or P-field shield region 320 may be biased independently with a separate voltage source. The contact with the top surface of the N-region can be either a Schottky barrier or an ohmic contact
[0038] P-shield regions 320 can be formed by a selective epitaxial deposition after the RIE etch of the silicon and after the formation of a sidewall oxide. The basic structure shown in FIG. 2B is applied to a trench MOSFET (N+ substrate) and also IGBT (P+ substrate) structure in FIG. 2A to improve the blocking capability with thin gate oxide. The structure shown in FIG. 2B can be applied to make a low barrier height diode such as the Schottky barrier diode, as shown in FIG. 2C , or the vertical JFET structure, as shown in FIG. 2D . The devices shown in FIGS. 2A-2D share the novel field shield structure, which is a P-region bounded by dielectricwalls on the sides and a PN junction below. The dielectric sidewalls prevent the spread of the P region expansion laterally by blocking the lateral diffusion of acceptors (e.g., boron) during device processing at high temperatures (e.g., above 800° C.). Of course, the polarities may be reversed in which case the field shield region would be formed of N-type material.
[0039] Each of field shield regions 320 is connected to P-body regions 316 and N+ source regions 312 in the third dimension, outside the plane of the drawing. FIGS. 3A and 3B illustrate how this can be done. FIG. 3A is a cross-sectional view taken at the end of one of trenches 306 showing how field shield regions 320 can be connected to P-body regions 316 and N+ source regions 312 . A P-well 328 is formed by ion implantation through a mask and diffusing a P-type dopant such as boron at the ends of trenches 306 . As the P-type dopant diffuses, the P-well expands laterally under the sidewall spacers 322 and merges with the field shield regions 320 . A P+ contact region 330 is formed beneath an opening in BPSG layer 324 at the surface of epi layer 304 to form an ohmic contact with metal layer 326 . P+ contact region 330 can be formed during the same process step as P+ body contact region 314 , shown in FIG. 2 . Since metal layer 326 is in electrical contact with N+ source regions 312 and P+ body contact regions 314 (see FIG. 2 ), field shield regions 320 are likewise in electrical contact with N+ source regions 312 and P+ body contact regions 314 .
[0040] Field shield regions 320 can also be connected to N+ source regions 312 and P+ body contact regions 314 by means of a wide trench, as shown in FIG. 3B . Wide trench 602 is an extension of trench 306 and may be located at the end of each rectangular trench cell, for example. At the bottom of trench 602 is a P shield region 604 , which is an extension of field shield region 320 . Also included in trench 602 are polysilicon spacers 606 , BPSG spacers 610 , and a metal plug 612 . Metal plug 612 extends downward from metal layer 326 . A P+ region 608 within P shield region 604 provides an ohmic contact with metal slug 612 . Therefore, since P shield region 604 is an extension of field shield region 320 , and since metal layer 326 is in electrical contact with N+ source regions 312 and P+ body contact regions 314 , this structure forms an electrical link between field shield region 320 and both N+ source regions 312 and P+ body contact regions 314 .
[0041] Referring again to FIG. 2 , with this structure depletion regions form on both sides of dielectric sidewalls or sidewall spacers 322 when MOSFET 30 is turned off, with N+ substrate 302 biased positive with respect to source regions N+. This increases the avalanche breakdown voltage of the device and allows N drift region 318 to be doped more heavily, reducing the R ds -on of MOSFET 30 .
[0042] FIGS. 4A-4H illustrate a process sequence that can be used to fabricate MOSFET 30 . The process begins with the formation of epi layer 304 on top of N+ substrate 302 . Because of the additional voltage blocking capability described above, epi layer 304 can be doped with an N-type dopant such as phosphorus to a concentration of 4×10 16 cm −3 to 8×10 16 cm −3 , for example, as compared with the normal doping concentration of 1×10 16 cm −3 to 2.5×10 16 cm −3 for a trench MOSFET with 30V breakdown. Prior to the process step illustrated in FIG. 4A , the structure is masked, and boron is implanted at a dose in the range of 1×10 13 cm −3 to 5×10 13 cm −3 to form P-wells, such as the P well 328 shown in FIG. 3A that is used to contact the field shield regions.
[0043] A second photoresist mask is then formed over what is to be the active area of the device, and a thick field oxide layer (e.g., 0.2-1.0 μm thick) is thermally grown in what are to be the voltage termination regions (die edges) of the MOSFET. Then, as shown in FIG. 4A , a pad oxide layer 404 is thermally grown on the surface of epi layer 304 and a silicon nitride layer 402 is deposited over pad oxide layer 404 . A third photoresist mask (trench mask) is formed atop nitride layer 402 , and nitride layer 402 and oxide layer 404 are etched through an opening in the trench mask to form openings 406 .
[0044] As shown in FIG. 4B , trenches 408 are etched through openings 406 . Trenches 408 can be relatively deep (e.g., 3 μm deep). An oxide layer which will form sidewall spacers 322 , which can be 0.05 to 0.1 μm thick, is grown thermally on the walls and bottoms of trenches 408 , and a directional reactive ion etch (RIE) process is used to remove the oxide layer from the bottoms of trenches 408 , leaving sidewall spacers 322 . Oxide layer 404 and nitride layer 402 are removed.
[0045] As shown in FIG. 4C , a P-type epitaxial layer is selectively deposited in the trenches 408 and then etched back to a thickness of 1.0-1.5 μm, for example. This forms field shield regions 320 .
[0046] Referring to FIG. 4D , the exposed portions of sidewall spacers 322 are removed by isotropic oxide etch, typically diluted HF (hydrofluoric acid), leaving the field shield regions 320 and the portions of sidewall spacers that are embedded between field shield regions 320 and N epi layer 304 .
[0047] As shown in FIG. 4E , gate oxide layer 310 is thermally grown on the exposed portions of the walls and the floor of trenches 408 and the upper portion of trenches 408 are then filled with polysilicon gate 308 , which is preferably heavily doped with an N-type dopant by ion implantation, POC13 or in situ. The polysilicon typically fills the top surface of epi layer 304 and is etched back by using a fourth, polysilicon mask so that it is coplanar with the top surface of epi layer 304 (although typically the polysilicon is etched back slightly into the trenches).
[0048] As shown in FIG. 4F , a P-type dopant is implanted and diffused to form P-body regions 316 . This can be done without a mask. A fifth photoresist mask (source mask) is then formed on the top surface of the structure, and the source mask is patterned photolithographically to create openings where the N+ source regions 312 are to be located. Next, an N-type dopant is implanted to form N+ source regions 312 . The mask is then removed.
[0049] BPSG layer 324 is deposited. A sixth photoresist mask (contact mask) is formed on BPSG layer 324 , with openings over the mesas, and BPSG layer 324 is etched, as shown in FIG. 4G . Using the contact mask, a second P-type dopant is implanted to form P+ body contact regions 314 . A thermal diffusion typically follows each of these implants to activate the dopant.
[0050] As shown in FIG. 4H , metal layer 326 is deposited over the top surface of the structure to make an ohmic contact with N+ source regions 312 and P+ body contact regions 314 . Metal layer 326 can be formed of Al:Si and can be from 1.3 to 5.0 μm thick. Typically a thin Ti/TiN barrier layer (not shown) is deposited under metal layer 326 . The result is MOSFET 30 , shown in FIG. 2 . A seventh photoresist mask (metal mask) is formed over metal layer 326 , and metal layer 326 is etched through the metal mask to separate metal layer 326 S that contacts N+ source regions 312 from the portion (not shown) that contacts the gate 308 .
[0051] FIGS. 5A-5G illustrate a process that can be used to form an alternative embodiment of the invention. This process can use as few as three masks and as many as seven masks. However, FIGS. 5A-5G illustrate a three-mask version of the process. The process described above in FIGS. 4A-4C is carried out, except that a blanket implant and diffusion to form P body region 316 is performed before pad oxide layer 404 and nitride layer 402 are deposited. As described above, trench mask is used to define the location of the trench. After field shield region 320 has been formed, as shown in FIG. 4C , pad oxide layer 404 and nitride layer 402 are left in place, as shown in FIG. 5A . The doping concentration of field shield region 320 may be in the range of 5×10 16 to 5×10 17 cm −3 , for example.
[0052] The exposed portions of oxide layers 322 are then removed. Gate oxide layer 310 is thermally grown on the exposed sidewalls of the trench and on the exposed upper surface of field shield region 320 . The upper portion of trench 408 is then filled with polysilicon gate 308 , which is preferably doped with an N-type dopant by ion implantation, POC13, or preferably in situ. The polysilicon is etched back so that its top surface adjoins nitride layer 402 . As described above a BPSG layer 324 is deposited on he top surface of the structure and etched back, using an RIE process, or planarized, using a chemical-mechanical polishing technique, until the top surface of BPSG layer 324 is coplanar with the top surface of nitride layer 402 , thereby forming a BPSG plug 470 . The resulting structure is shown in FIG. 5B .
[0053] Nitride layer 402 is then removed, preferably without a mask, to yield the structure shown in FIG. 5C .
[0054] As shown in FIG. 5D , the structure is then heated in a dry-oxidation furnace (e.g., at 900-1000° C. for 10-30 minutes) to oxidize the exposed sidewalls of polysilicon gate 308 , forming oxide layers 472 .
[0055] As shown in FIG. 5E , pad oxide layer 404 is removed, and a P-type dopant is implanted and diffused to adjust the threshold voltage of the MOSFET to be formed. The areas in which this dopant is located is labeled 474 . An N-type dopant is implanted and diffused to form N+ source layer 476 .
[0056] As shown in FIG. 5F , a second, N+ doped polysilicon layer is deposited over the top surface of the structure, and is then removed using a directional RIE process to leave N+ polysilicon spacers 478 adjacent the sidewalls of BPSG layer 470 . Polysilicon spacers 478 also abut the exposed surfaces of oxide layers 472 . A second BPSG layer is deposited over the top surface of the structure and is then removed using a directional RIE process to leave BPSG spacers 480 adjacent polysilicon spacers 478 . As a result, at this point of the process both polysilicon spacers 478 and BPSG spacers 480 are attached to the sides of BPSG layer 470 . Alternatively, a silicon nitride layer could be deposited instead of the second BPSG layer in which case spacers 480 would be made of nitride.
[0057] Using BPSG layer 470 and spacers 478 and 480 as a mask, the top surface of epi layer 304 is etched using an RIE process to remove the exposed portions of N+ source layer 476 . Using the same mask, a P-type dopant is implanted at a relatively low energy to form P+ body contact regions 482 . This produces the structure illustrated in FIG. 5F .
[0058] BPSG layer 470 and BPSG (or nitride) spacers 480 are etched (e.g., about 500 Å) to expose more of N+ polysilicon spacers 478 and N+ source layer (now region) 476 . In this process all of BPSG spacers may be removed.
[0059] As shown in FIG. 5G , a barrier metal layer 481 formed of Ti/TiN is deposited by sputtering or CVD. Barrier metal layer 481 could be 1000 Å thick. This is followed by the deposition of metal layer 326 , which could be from 2 to 8 μm thick. Metal layer 326 could be made of Al and could include up to 1% Si and 0.4% Cu. A photoresist metal mask is then typically formed atop metal layer 326 , and metal layer 326 is etched to separate the metal layer 324 S that contacts the N+ source regions 476 (shown in FIG. 5G ) from the portion (not shown) that contacts the gate 308 .
[0060] The result of this process is MOSFET 40 , shown in FIG. 5G .
[0061] In an alternative embodiment, nitride spacers 486 are substituted for polysilicon spacers 478 and BPSG spacers 480 , producing MOSFET 42 shown in FIG. 6
[0062] FIG. 7 shows an alternative embodiment according to the invention. Again, MOSFET 50 is formed in epi layer 304 that is grown on N+ substrate 302 . Trenches 306 are formed in epi layer 304 , and trenches 306 are lined with gate oxide layer 310 and filled with polysilicon gate 308 . Deep trenches 450 are formed in the mesas between trenches 306 . The walls of each trench 450 are lined with oxide sidewall spacers 458 , and each trench 450 contains a P shield region 452 and a P+ contact region 456 . Within the mesa between trenches 306 are a P-body region 454 , N+ source regions 312 and P+ body contact regions 460 . The top surface of each gate 308 is covered with a BPSG layer 324 . Source metal layer 326 S overlies BPSG layer 324 and makes electrical contact with N+ source regions 312 , P+ body contact regions 460 and P+ contact region 456 . Similarly, metal layer 325 contacts N+ substrate 302 , which functions as the drain. The remainder of epi layer 304 , outside the mesa between trenches 306 , includes N drift region 318 , which is more lightly doped than N+ substrate 302 .
[0063] Thus, P+ body contact regions 460 , P-body regions 454 , N+ source regions 312 , P+ contact region 456 and P shield region 452 are all biased to the source potential through metal layer 326 S. When MOSFET is blocking voltage in an off condition, depletion regions spread outward from sidewall spacers 458 into N drift region 318 . Thus, a vertical junction field-effect transistor (JFET) forms between adjacent deep trenches 450 , underneath trenches 306 . The N drift region 318 is largely depleted by the adjacent deep trenches 450 when MOSFET is blocking a voltage. This increases the breakdown potential of MOSFET 50 and protects the corners of trenches 306 and gate oxide layers in trenches 306 from the high electric field that would otherwise result from a high source-to-drain voltage and high gate-to-drain voltage. N drift region 318 can be doped to a higher concentration than would otherwise be possible, reducing the on-resistance of MOSFET 50 .
[0064] MOSFET 50 can be fabricated with a conventional process, except that an additional mask and etch for the deep trenches 450 is required. An oxide layer is grown on the sidewalls and floor of the deep trenches 450 , and the oxide layer is removed from the floor of the deep trenches 450 by an RIE process to leave oxide spacers 458 . A selective epi growth process is used to form P shield regions 452 . After the formation of the P shield regions 452 , a normal trench MOSFET process can be used to fabricate trenches 306 and the remainder of MOSFET 50 .
[0065] Referring again to FIG. 3B , a manufacturing process for making electrical contact with the field shield regions by means of a wide trench is illustrated in FIGS. 8A-8C . This is part of the process flow illustrated in FIGS. 4A-4H . Pad oxide layer 402 and nitride layer 404 are patterned ( FIG. 4A ) so as to form wide trenches 602 in the locations on the chip where the field shield region is to be contacted. The process steps described in FIGS. 4B-4D are then undertaken to form P shield region 604 . When N+ polysilicon layer 308 is deposited ( FIG. 4E ), it conforms to the contours of wide trench 602 , as shown in FIG. 8A . When BPSG layer 324 is deposited ( FIG. 4G ), it likewise conforms to the contours of wide trench 602 , as shown in FIG. 8B . Referring further to FIG. 8B , when BPSG layer 324 is masked, an opening is formed in the central region of wide trench 602 , and BPSG layer 324 , polysilicon layer 308 and the thin oxide layer over P shield region 604 are etched through this opening to form the structure shown in FIG. 8B . This produces polysilicon spacers 606 and BPSG spacers 610 on the walls of wide trench 602 . P shield region 604 contains a P+ region 608 , which can be formed at the same time as P+ body contact region 314 . When metal layer 326 is deposited ( FIG. 4H ), it flows into wide trench 602 and forms an electrical contact with P shield region 604 , as shown in FIG. 8C
[0066] The use of this process in the basic process sequence shown in FIGS. 5A-5G produces a similar result, except that, as shown in FIG. 9 there is no polysilicon layer 308 on the die surface, only inside the trenches. Therefore, in the three-mask process, N+ polysilicon and BPSG sidewall spacers are formed on the vertical surfaces of BPSG layer 324 . As mentioned above, a portion of metal layer 326 (not shown) is used to contact the polysilicon gate 308 .
[0067] FIG. 10 shows a termination edge region 650 that may be used with the field shield contact structure shown in FIG. 3A , which contains a P well. A section 404 A of oxide layer 404 is left remaining on top of epi layer 304 , with an opening 654 adjacent the end of trench 306 . This can be done in the seven-mask process illustrated in FIGS. 4A-4H . A heavily-doped N+ polysilicon layer 308 A is formed over oxide layer 404 A. Polysilicon layer 308 A can be a portion of the polysilicon layer that is deposited to form gate 308 (see FIG. 4E ) and a mask can be applied before the polysilicon is etched back into the trench to form layer 308 A. Using the contact mask, a portion 324 A of BPSG layer 324 is left remaining on top of polysilicon layer 308 A, with an opening 658 over polysilicon layer 308 A. Finally, after metal layer 326 has been patterned, using the metal mask, the portion 326 S that contacts the source regions also contacts P+ region 330 and polysilicon layer 308 A.
[0068] If the field shield is contacted in the manner shown in FIG. 9 , using a wide trench, a termination structure of the kind shown in FIG. 11 may be employed. In the edge termination region 700 , oxide layer 310 A, N+ polysilicon layer 308 A and three trenches 702 A, 702 B and 702 C are formed by using the trench and contact mask levels. There are no active field plates on the surface of the voltage termination structure shown in FIG. 11 , where the process is reduced to three mask levels. The three trenches 702 A, 702 B and 702 C are typically longitudinal trenches that are parallel to each other and are parallel to and adjacent to an edge of the semiconductor die. Trenches 702 A- 702 C may be formed in the same manner and at the same time as trenches 306 in the active region of the MOSFET (see FIG. 5B ). The internal structure of trenches 702 A- 702 C is identical to that of trenches 306 . Each P-shield region 320 and each polysilicon region 308 A “floats” with respect to both source and the drain potentials, because there is no direct electrical contact. Therefore, the three trenches filled with polysilicon 308 A, isolated by silicon dioxide layer 310 A, act like “floating” p-n junctions (floating rings) with a field plate to reduce the electric field by dividing the voltage among three trenches 702 A- 702 C. Either the P field shield region 320 below each of trenches 702 A- 702 C is in electrical contact with the poly silicon 308 A or floating. The contact mask is designed such that a portion 324 B of BPSG layer 324 is left over trenches 702 A- 702 C. BPSG layer 324 B is removed from the active region of the device side to allow metal layer 326 S, which is in contact with the N+ source regions 476 , to make contact with P+ region 482 . BPSG layer 324 is also removed from the saw street area of the chip (right side of FIG. 11 ). Polysilicon spacers 478 and BPSG spacers 480 are also shown on the sidewalls of BPSG layer 324 B in FIG. 11 .
[0069] FIGS. 12A and 12B illustrate a structure for contacting the gate 308 when the process shown in FIGS. 4A-4H is used to manufacture the MOSFET. As shown in FIG. 12A , oxide layer 404 are nitride layer 402 are masked so that they are not removed at the point described above (see FIG. 4B ). Similarly, when the polysilicon layer which will form gate 308 is deposited, and before it is etched back into the trench, the polysilicon layer is masked in the area where the gate contact is to be made, forming polysilicon layer 308 B, which is essentially an extension of gate 308 outside the trench. Polysilicon layer 308 B is thus in electrical contact with gate 308 . Nitride layer 324 D is an extension of nitride layer 324 . An opening is formed in the contact mask (see FIG. 4G ) so that when BPSG layer 324 D is etched, an opening 710 is formed. When metal layer 326 is deposited, it fills the opening 710 and makes contact with polysilicon layer 308 B. The metal mask is configured such that the section of metal layer 326 that contacts polysilicon layer 308 B becomes the gate metal portion 326 G.
[0070] FIGS. 13A and 13B illustrate a way of contacting the gate if the process described in FIGS. 5A-5G is used to manufacture the MOSFET. This process is similar to the one described in FIGS. 5F-5G , except that polysilicon is inside a wider trench region, 306 W.
[0071] FIGS. 14A-14C illustrate three patterns in which the gate trenches and mesas may be formed: stripe, square and hexagonal geometries. Devices of the present invention may be formed in any of these or other trench lay out patterns.
[0072] While specific embodiments of this invention have been described, it should be understood that these embodiment are illustrative, and not limiting. Many other embodiments according to this invention will be apparent to persons of skill in the art. For example, while the embodiments described above involved MOSFETs, this invention is also applicable to other semiconductor devices, such as trench insulated gate bipolar transistors (IGBTs), vertical power junction field-effect transistors (JFETs) and power bipolar devices. Moreover, while N-channel devices have been described, these principles of this invention can be used with P-channel devices by reversing the polarities.
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A semiconductor device includes a field shield region that is doped opposite to the conductivity of the substrate and is bounded laterally by dielectric sidewall spacers and from below by a PN junction. For example, in a trench-gated MOSFET the field shield region may be located beneath the trench and may be electrically connected to the source region. When the MOSFET is reverse-biased, depletion regions extend from the dielectric sidewall spacers into the “drift” region, shielding the gate oxide from high electric fields and increasing the avalanche breakdown voltage of the device. This permits the drift region to be more heavily doped and reduces the on-resistance of the device. It also allows the use of a thin, 20 Å gate oxide for a power MOSFET that is to be switched with a 1V signal applied to its gate while being able to block over 30V applied across its drain and source electrodes, for example.
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[0001] FIELD OF THE INVENTION
[0002] The present invention relates to a space code block coding and spreading apparatus and method for transmission diversity and a Code Division Multiple Access (CDMA) diversity transmitter and a CDMA mobile station receiver using the same. More particularly, the invention is directed to a space code block coding and spreading apparatus and method for transmission diversity, and a CDMA diversity transmitter and a CDMA mobile station receiver using it, which are capable of improving the performance of a system in wireless channel environments by allowing a transmission diversity to be made within one symbol interval in a CDMA communication system.
[0003] DESCRIPTION OF RELATED ART
[0004] FIG. 1 shows a view describing the concept of a conventional transmission diversity method using a space time block coding technique.
[0005] One of the conventional transmission diversity techniques is “Space Time Block Coding (STBC)” proposed in “IEEE Journal on select areas in communications” by Siavash M. Alamouti in 1998. Such an STBC scheme is a scheme that performs a diversity encoding with respect to data to be transmitted in space (antenna) and time domains and then transmits it, as shown in FIG. 1 .
[0006] In other words, in a basic mode where the number of transmission antenna is one, if a modulation symbol transmitted at an arbitrary timeslot t 101 is s 0 and a modulation symbol transmitted at its adjacent timeslot t+T 102 is s 1 , the transmission diversity technique using the STBC encoding method proposed by Alamouti transmits the first symbol s 0 via a first antenna (antenna 0 ) at a timeslot t 111 and its conjugate complex s 0 * via a second antenna (antenna 1 ) at its adjacent timeslot t+T 122 , as can be seen from FIG. 1 . The second symbol s 1 is transmitted via the second antenna (antenna 1 ) at a timeslot t 121 and its negative conjugate complex −s 1 * via the first antenna (antenna 0 ) at its adjacent timeslot t+T 112 . Namely, the Alamouti's STBC encoding method is a method which acquires a diversity gain by transmitting each modulation symbol at two adjacent time intervals via different antennas.
[0007] FIG. 2 a is a circuitry diagram showing a configuration of a transmitter that implements a conventional STBC transmission diversity method in Multi Carrier-CDMA (MC-CDMA) system. That is, FIG. 2 a represents a configuration of a base station transmitter where one channelization code is assigned to an arbitrary kth user, in the MC-CDMA system to which the Alamouti's STBC encoding method is applied.
[0008] Specifically, channel-encoded data is first modulated at a modulator 201 using Quadrature Phase Shift Keying (QPSK) or M-ary Quadrature Amplitude Modulation (QAM) and then applied to an STBC encoder 202 .
[0009] The STBC encoder 202 gets two symbols every two Orthogonal Frequency Division Multiplexing (OFDM) symbol intervals and performs STBC encoding to obtain an encoded symbol for each of two diversity antennas, as shown in FIG. 2 a . In other words, during a first symbol interval, s k,0 and s k,1 are outputted to paths for a first and a second antennas, respectively, while, during a second symbol interval, −s* k,1 and s* k,0 are provided to the paths for the first and the second antennas, respectively. Here, the asterisk “*” represents a conjugate complex.
[0010] The two outputs from the STBC encoder 202 are duplicated at each of duplicators 203 a and 203 b by N every symbol interval; and then each of the duplicated values is multiplied by an orthogonal code with the length of N assigned to a current channel at each of orthogonal code multipliers 204 a and 204 b . Here, the orthogonal codes multiplied with respect to the two antenna paths are C (k,0) =[C 0 (k,0) C 1 (k,0) . . . C N−1 (k,0) ] T which is given as the same one. And, k indicates a kth user and T represents a transposition matrix.
[0011] The N symbols with respect to each of the antenna paths multiplied by the orthogonal codes are combined with symbols of other channels at channel combiners 205 a and 205 b , respectively. Outputs from the channel combiners 205 a and 205 b are multiplied by scrambling codes at scramblers 206 a and 206 b and then converted into time domain signals at parallel/serial converters 208 a and 208 b via Inverse Fast Fourier Transformers (IFFTs) 207 a and 207 b . Thereafter, Cyclic Prefix (CP) is inserted into the signals at CP inserters 209 a and 209 b ; and then the CP-inserted signals are amplified and converted into RF signals at IF/RF processors 210 a and 210 b to transmit via antennas 211 a and 211 b.
[0012] As described above, the conventional STBC diversity method acquires the diversity gain by transmitting the arbitrary one symbol to the different antennas via the two paths at the two adjacent symbol intervals, that is, two. different time intervals.
[0013] FIG. 2 b is a view describing the concept of a conventional STBC transmission diversity method in MC-CDMA system.
[0014] As shown in FIG. 2 , a modulation symbol s k,0 is transmitted via a first antenna (antenna 0 ) at a time T 0 (OFDM symbol interval 0 ) and then its conjugate complex s* k,0 via a second antenna (antenna 1 ) at a time T 1 (OFDM symbol interval 1 ). Conversely, a modulation symbol s k,1 is transmitted via the second antenna (antenna 1 ) at the time T 0 (OFDM symbol interval 0 ) and then its negative conjugate complex −s* k,1 via the first antenna (antenna 0 ) at the time T 1 (OFDM symbol interval 1 ).
[0015] At a receiver of the transmitter using the conventional STBC diversity method, s k,0 and s k,1 are recovered using the symbols received at the two adjacent time intervals.
[0016] In other words, signals received at each of the intervals T 0 and T 1 are transformed by taking Fast Fourier Transform (FFT) and then descrambled. If symbols obtained by adding the descrambled signals to a signal despread to C (k,0) are r 0 and r 1 , respectively, the symbols may be represented as:
r 0 =α 0 ( T 0 ) s k,0 +α 1 ( T 0 ) s k,1 +n 0
r 1 =−α 0 ( T 1 ) s* k,1 +α 1 ( T 1 ) s* k,0 +n 0 Eq. (1)
[0017] In Eq. (1) above, α α (T e ) implies a channel component of signal received via an ath reception antenna at an interval T e , which generally has a Rayleigh distribution. And, n i represents a reception noise component of despread and added signal. For example, if a speed of a mobile station is very slow, it satisfies the following equality:
α α ( T 0 )≅α α ( T 1 )
Further, if the above equality is given by α α , the result of STBC decoding may be defined as follows:
ŝ 0 =r 0 α* 0 +r* 1 α 1 =|α 0 | 2 s 0 +n 0 α* 0 +n* 1 α 1
ŝ 1 =r 0 α* 1 −r* 1 α 0 =|α 1 | 2 s 1 +n 0 α* 1 −n* 1 α 0 Eq. (2)
[0018] If the speed of mobile station is slow, the result of the STBC decoding may be given as Eq. (2) above; and but, if the speed of mobile station is fast, α α (T 0 )≠α α (T 1 ), and thus Eq. (2) above is not satisfied. This causes any interference in each determinant variable. Consequently, as the speed of the mobile station is faster, the interference increases, thereby giving a reason that greatly lowers the performance of system.
[0019] FIG. 3 is a circuitry diagram of a transmitter that implements a conventional MC-CDMA diversity method using a multi-code when a data transmission rate is twice. Particularly, FIG. 3 represents an MC-CDMA base station transmitter employing a general STBC transmission diversity technique when two channelization codes are assigned to an arbitrary user.
[0020] Here, the meaning that the two channelization codes are assigned is that the data transmission rate is twice compared to an instance of assigning a single code, as in FIG. 1 . That is, if it is assumed that the data transmission rate of the example shown in FIG. 1 is a basic data transmission rate R, the data transmission rate of the example in FIG. 3 becomes 2R.
[0021] As can be seen from FIG. 3 , two pairs of modulation symbols assigned to each of two codes, s k,0 and s k,1 , and s k,2 and s k,3 , are first processed at a serial/parallel converter 301 for their serial to parallel conversions and then each of them is STBC-encoded at STBC encoders 302 a and 302 b . A more easy description thereof will be given below with reference to FIG. 4 . The pair of symbols s k,0 and s k,1 is STBC-encoded and then spread to C (k,0) =[C 0 (k,0) C 1 (k,0) . . . C N−1 (k,0) ] T ; and the pair of symbols s k,2 and s k,3 is STBC-encoded and then spread to C (k,1) =[C 0 (k,1) C 1 (k,1) . . . C N−1 (k,1) ] T .
[0022] In this case, the arbitrary one symbol is also transmitted to different antennas via two paths at two adjacent symbol intervals, i.e., different time intervals; and therefore, the performance of system is very lowered in high speed mobile station environments.
SUMMARY OF THE INVENTION
[0023] It is, therefore, a primary object of the present invention to provide a space code block coding and spreading apparatus and method for transmission diversity and a CDMA diversity transmitter using it, which are capable of improving the performance of system in wireless channel environments by allowing a transmission diversity to be made within one symbol interval in CDMA communication system.
[0024] Another object of the present invention is to provide a CDMA mobile station receiver for receiving a transmission diversity signal transmitted through the CDMA diversity transmitter and method thereof.
[0025] In accordance with one aspect of the present invention, there is provided a Space Code Block Coding (SCBC) and spreading apparatus for transmission diversity in a Code Division Multiple Access (CDMA) communication system, the apparatus comprising: an encoding means for generating a predetermined number of different transmission data with respect to a plurality of modulation symbols inputted during one modulation symbol interval; an orthogonal code generation means for producing orthogonal codes; a spreading means for spreading each of the transmission data generated from the encoding means using the orthogonal codes generated from the orthogonal code generation means; and a combining means for combining the transmission data spread at the spreading means to provide combined data for each transmission antenna path so that a transmission diversity is made within said one modulation symbol interval.
[0026] In accordance with another aspect of the present invention, there is provided an SCBC and spreading method for transmission diversity in a CDMA communication system, the method comprising the steps of: (a) generating a predetermined number of different transmission data with respect to a plurality of modulation symbols inputted during one modulation symbol interval; (b) spreading each of the transmission data generated at said step (a) using orthogonal codes; and (c) combining the transmission data spread at said step (b) to ,provide a baseband signal for each transmission antenna path so that a transmission diversity is made within said one modulation symbol interval.
[0027] In accordance with still another aspect of the present invention, there is provided a CDMA diversity transmitter for a CDMA communication system, comprising: a modulation means for modulating channel-coded symbol data; a serial/parallel conversion means for converting a plurality of modulation symbols inputted every modulation symbol interval from the modulation means to provide pairs of modulation symbols made every predetermined number of modulation symbols in parallel; a plurality of SCBC and spreading means for generating and spreading a predetermined number of different transmission data every each of the pairs of modulation symbols provided by the serial/parallel conversion means, and combining the spread transmission data so that a transmission diversity is made within one modulation symbol interval; a combining means for combining the outputs from each of the plurality of SCBC and spreading means to generate a baseband signal for each antenna path; and a wireless signal processing means for converting each of the baseband signals into a wireless signal.
[0028] In addition, the CDMA diversity transmitter further comprises an Inverse Fast Fourier Transform (IFFT) means for transforming each of the baseband signals in the frequency domain generated from the combining means for each antenna path into a time domain signal, in case where the CDMA communication system employs a Multi-Carrier CDMA (MC-CDMA) scheme, wherein each of the SCBC and spreading means performs the spreading process in the frequency domain.
[0029] Furthermore, the CDMA diversity transmitter further comprises a scrambling means for scrambling the outputs from the combining means for each antenna path; and a Cyclic Prefix (CP) insertion means for inserting CP into each of the outputs from the IFFT means.
[0030] Moreover, the CDMA diversity transmitter further comprises a multiplexing means for providing modulation symbols of two user channels to be transmitted within one modulation symbol interval to the serial/parallel conversion means alternately, in case where the number of transmission antennas of the transmitter are two and one orthogonal code is assigned to each of a plurality of user channels.
[0031] In accordance with still yet another aspect of the present invention, there is provided a CDMA mobile station receiver for receiving a diversity signal transmitted in a CDMA communication system, comprising: a wireless signal processing means for converting a wireless signal received via a reception antenna into a baseband signal; a despreading means for despreading the baseband signal using orthogonal codes; a channel estimation means for estimating a channel value for a wireless path between a transmission antenna of the CDMA communication system and the reception antenna from the despread signal from the despreading means; an SCBC decoding means for recovering a transmitted signal by performing SCBC decoding using the channel estimated value from the channel estimation means and the despread signal from the despreading means; and a bit calculation means for calculating a bit value from the output from the SCBC decoding means.
[0032] In addition, the CDMA mobile station receiver further comprises a Fast Fourier Transform (FFT) means for transforming the baseband signal into a frequency domain signal in case where the CDMA communication system employs MC-CDMA scheme.
[0033] Moreover, the CDMA mobile station receiver further comprises: a CP removal means for removing a CP from the baseband signal outputted from the wireless signal processing means; a descrambling means for descrambling the frequency domain signal from the FFT means to provide it to the SCBC decoding means and the channel estimation means; and a channel decoding means for performing channel decoding with respect to the output from the bit calculation means.
[0034] The other objectives and advantages of the invention will be understood by the following description and will also be appreciated by the embodiments of the invention more clearly. Further, the objectives and advantages of the invention will readily be seen that they can be realized by the means and its combination specified in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] The above and other objects and features of the instant invention will become apparent from the following description, of preferred embodiments taken in conjunction with the accompanying drawings, in which:
[0036] FIG. 1 is a view describing the concept of a conventional transmission diversity method using a space time block coding technique;
[0037] FIG. 2 a is a circuitry diagram showing a configuration of a transmitter that implements a conventional STBC transmission diversity method in an MC-CDMA system;
[0038] FIG. 2 b is a view describing the concept of a conventional STBC transmission diversity method in an MC-CDMA system;
[0039] FIG. 3 is a circuitry diagram of a transmitter that implements a conventional MC-CDMA diversity method using a multi-code when a data transmission rate is twice;
[0040] FIG. 4 is a view describing the concept of a conventional MC-CDMA diversity method using a multi-code when a data transmission rate is twice;
[0041] FIG. 5 a is a circuitry diagram showing a configuration of one embodiment of a Space Code Block Coding (SCBC) and spreading apparatus for transmission diversity in accordance with the present invention;
[0042] FIG. 5 b is a conceptual view describing a SCBC and spreading method for transmission diversity in accordance with the present invention;
[0043] FIG. 6 a is a circuitry diagram showing a configuration of one embodiment of a multi-code (e.g., two codes) MC-CDMA diversity transmitter using SCBC in accordance with the present invention;
[0044] FIG. 6 b is a view describing the concept of the SCBC transmission diversity in the MC-CDMA diversity transmitter shown in FIG. 6 a in accordance with the present invention;
[0045] FIG. 7 shows a view explaining the concept of an SCBC transmission diversity method where 2M codes are assigned to an arbitrary user in accordance with the present invention;
[0046] FIG. 8 is a circuitry diagram showing a configuration of one embodiment of an MC-CDMA diversity transmitter using SCBC in case where 2M codes are assigned to an arbitrary user in accordance with the present invention;
[0047] FIG. 9 is a view describing the concept of a transmission diversity method where one orthogonal code is assigned to each of arbitrary two users' channels in accordance with the present invention;
[0048] FIG. 10 is a circuitry diagram showing a configuration of one embodiment of a CDMA mobile station receiver with respect to the transmission diversity in accordance with the present invention;
[0049] FIG. 11 a is a circuitry diagram depicting a configuration of one embodiment of a DS-CDMA diversity transmitter using SCBC in case where 2M codes are assigned to an arbitrary user in accordance with the present invention; and
[0050] FIG. 11 b is a circuitry diagram illustrating a configuration of the SCBC and spreading unit in accordance with the invention shown in FIG. 11 a.
DETAILED DESCRIPTION OF THE INVENTION
[0051] The above-mentioned objectives, features, and advantages will be more apparent from the following detailed description in association with the accompanying drawings; and based on this, the invention will be readily conceived by those skilled in the art to which the invention belongs. Further, in the following description, well-known arts will not be described in detail if it seems that they could obscure the invention in unnecessary detail. Hereinafter, a preferred embodiment of the present invention will be set forth in detail with reference to the accompanying drawings.
[0052] FIG. 5 a is a circuitry diagram showing a configuration of one embodiment of an SCBC and spreading apparatus for transmission diversity in accordance with the present invention, and FIG. 5 b is a conceptual view describing a SCBC and spreading method for transmission diversity in accordance with the present invention. Here, a method for performing the diversity encoding in space (antenna) and code domain is presented.
[0053] As shown in FIG. 5 a , the SCBC and spreading apparatus 500 in accordance with the present invention comprises an SCBC encoder 501 , orthogonal code generators 502 a and 502 b , spreaders 503 a to 503 d composed of multipliers, and combiners 504 a and 504 b composed of adders.
[0054] The SCBC encoder 501 simultaneously outputs four symbols, e.g., s 0 , s 1 , −s 1 *, s 0 *, as transmission data, with respect to two input symbols s 0 and s 1 at arbitrary one modulation symbol interval. That is, the SCBC 501 simultaneously provides four symbols s 0 , s 1 , −s 1 *, s 0 * in response to the two input symbols s 0 and s 1 in parallel. The four output symbols include the two input symbols s 0 and s 1 , the input symbol's conjugate complex s 0 *, and the input symbol's negative conjugate complex −s 1 *.
[0055] Among the four output symbols from the SCBC encoder 501 , two, e.g., s 0 and −s 1 *, are spread by binary orthogonal code C (j) =[c 0 (j) c 1 (j) c 2 (j) . . . c N−1 (j) ] T , and the remaining two symbols, i.e., s 1 and s 0 * are spread by another binary orthogonal code C (k) =[c 0 (k) c 1 (k) c 2 (k) . . . . c N−1 (k) ] T . Here, T indicates a transposition matrix. And, the two orthogonal codes are orthogonal codes whose cross correlations are “ 0 ”. Further, the orthogonal codes in the invention are used as direct sequence spread spectrum codes on the frequency axis in case of MC-CDMA or Frequency-Hopping MC-CDMA (FH-MC-CDMA), while being used as direct sequence spread spectrum codes on the time axis in case of Direct Sequence-CDMA (DS-CDMA)(see FIG. 11 a ).
[0056] The orthogonal code generators 502 a and 502 b generate desired binary orthogonal codes, and the multipliers 503 a to 503 d multiply the symbols outputted from the SCBC encoder 501 by the corresponding orthogonal codes, respectively. Outputs from the multipliers 503 a to 503 d are added at the adders 504 a and 504 b and then transmitted to antennas.
[0057] Hereinafter, the concept of the SCBC and spreading method in accordance with the present invention will be described in more detail with reference to FIG. 5 b.
[0058] A signal s 0 C (j) created by spreading the symbol s 0 to the orthogonal code C (j) is added to a signal s 1 C (k) produced by spreading the symbol s 1 to the orthogonal code s 1 C (k) to output an added signal to a path for the first antenna (antenna 0 ). And, a signal S 0 *C (k) created by spreading the symbol s 0 * to the orthogonal code C (k) is added to a signal −s 1 *C (j) obtained by spreading the symbol −s 1 * to the orthogonal code C (j) to provide an added signal to a path for the second antenna (antenna 1 ).
[0059] As a result, a baseband signal transmitted via the first transmission antenna (antenna 0 ) at the arbitrary transmission symbol interval becomes S 0 C (j) +s 1 C (k) , and a baseband signal transmitted via the second transmission antenna (antenna 1 ) at the arbitrary transmission symbol interval becomes S 0 *C (k) −s 1 *C (j) . These two signals are transmitted at one symbol interval concurrently. This feature is the greatest difference of the SCBC transmission diversity method of the invention, which is distinguishable from the conventional STBC transmission diversity method.
[0060] Namely, the SCBC and spreading method of the invention performs the space code block coding with respect to the modulated symbols in such a way that the transmission diversity is made within one symbol interval every fixed number of modulated symbols (e.g., two, s 0 and s 1 , in FIGS. 5 a and 5 b ).
[0061] The present invention may be applied to the DS-CDMA system that performs the direct sequence spread spectrum on the time axis, and also to the MC-CDMA system or FH-MC-CDMA system that carries out the direct sequence spread spectrum on the frequency axis or two-dimensional spread spectrum on both of the time and frequency axes.
[0062] FIG. 6 a is a circuitry diagram showing a configuration of one embodiment of a multi-code (e.g., two codes) MC-CDMA diversity transmitter using the SCBC in accordance with the present invention, which represents a configuration of a base station transmitter in case where the SCBC transmission diversity method is applied to the MC-CDMA system that performs the direct sequence spread spectrum on the frequency axis.
[0063] In case where a data transmission rate is R when the number of symbols to be transmitted is one within one modulation symbol interval, FIG. 6 a shows an example where a data transmission rate of a kth channel is 2R.
[0064] In FIG. 6 a , encoded data of the kth channel with the data transmission rate of 2R is first modulated at a modulator 601 and then two modulated symbols s k,0 and s k,1 are applied to an SCBC encoder 6021 every symbol interval. Then, the SCBC encoder 6021 provides four outputs s k,0 , s k,1 , −s* k,1 , and s* k,0 using the inputted two modulation symbols s k,0 and s k,1 , wherein each output symbol is duplicated at duplicators 6022 a to 6022 d by N.
[0065] Orthogonal code multipliers 6023 a to 6023 d multiply each of the four outputs s k,0 , s k,1 , −s* k,1 , and s* k,0 by a corresponding orthogonal code. Through such multiplication operation, each of the four outputs s k,0 , s k,1 , −s* k,1 , and s* k,0 is spread by any of two orthogonal codes, i.e., C (k,0) =[c 0 (k,0) c 1 (k,0) c 2 (k,0) . . . c N−1 (k,0) ] T and C (k,1) =[C 0 (k,1) c 1 (k,1) c 2 (k,1) . . . c N−1 (k,0) ] T assigned to the kth channel on the frequency axis.
[0066] Among the spread signals, the signals s k,0 C (k,0) and s k,1 C (k,1) are added at an adder 6024 a for each subcarrier to output an added signal to a path for a first antenna 609 a , and the signals S* k,0 C (k,1) and −S* k,1 C (k,0) are added at an adder 6024 b for each subcarrier to provide an added signal to a path for a second antenna 609 b . The signals s 0 outputted are again added to signals of other channels at adders 603 a and 603 b for each antenna and subcarrier and then multiplied by scrambling codes at scramblers 604 a and 604 b . In the forgoing, s k,0 C (k,0) , s k,1 C (k,1) , s* k,0 C (k,1) , −s* k,1 C (k,0) are all vectors.
[0067] The outputs from the scramblers 604 a and 604 b are IFFT-transformed at IFFT units 605 a and 605 b and then processed at parallel/serial converters 606 a and 606 b to provide arranged serial data. And then, CP is inserted into each of the outputs from the parallel/serial converters 606 a and 606 b at CP inserters 607 a and 607 b ; and the CP-inserted signals are multiplied by a given gain and then converted into RF wireless signals at IF/RF processors 608 a and 608 b to transmit via the antennas 609 a and 609 b.
[0068] Meanwhile, FIG. 6 b shows a view describing the concept of the SCBC transmission diversity in the MC-CDMA diversity transmitter shown in FIG. 6 a.
[0069] It can be seen from FIG. 6 b that the outputs from the modulator 601 , s k,0 and s k,1 , are SCBC-processed and spread to transmit s k,0 C (k,0) +s k,1 C (k,1) to the antenna 0 609 a and s* k,0 C (k,1) −s* k,1 C (k,0) to the antenna 1 609 b . In other words, it can be found that the transmission diversity can be made within one symbol interval.
[0070] FIG. 7 shows a view explaining the concept of an SCBC transmission diversity method where 2M codes are assigned to an arbitrary user in accordance with the present invention. That is, FIG. 7 presents an example where the transmission diversity method in accordance with the present invention is applied in case where 2M orthogonal codes are assigned to a kth user.
[0071] Among 2M modulation symbols, each pair of two symbols is SCBC-encoded, spread by an orthogonal code corresponding to each symbol, added for each antenna, and then transmitted simultaneously, within one modulation symbol interval.
[0072] For instance, if 2mth symbol and (2m+1)th symbol among the 2M modulation symbols are s k,2m and s k,2m+1 , respectively, each pair of two symbols is SCBC-encoded, wherein m is 0, 1, 2, . . . , M−1. And then, each of the SCBC-encoded symbols is spread by C (k,2m) =[c 0 (k,2m) c 1 (k,2m) c 2 (k,2m) . . . c N−1 (k,2m) ] T and C (k,2m+1) =[c 0 (k,2m+1) c 1 (k,2m+1) c 2 (k,2m+1) . . . c N−1 (k,2m+1) ] T , respectively, added for each antenna and then outputted.
[0073] Hence, a component transmitted to the first antenna (antenna 0 ) becomes
∑ m = 0 M - 1 ( s k , 2 m C ( k , 2 m ) + s k , 2 m + 1 C ( k , 2 m + 1 ) )
and a component to the second antenna (antenna 1 ) becomes
∑ m = 0 M - 1 ( s k , 2 m * C ( k , 2 m + 1 ) - s k , 2 m + 1 * C ( k , 2 m ) ) .
And, since the number of the orthogonal codes used is 2M, the data transmission rate becomes 2MR.
[0074] FIG. 8 is a circuitry diagram showing a configuration of one embodiment of an MC-CDMA diversity transmitter using SCBC in case where 2M codes are assigned to an arbitrary user in accordance with the present invention. That is, FIG. 8 offers a structure of an MC-CDMA transmitter employing a transmission diversity technology in accordance with the present invention in case where 2M orthogonal codes are assigned to a kth user.
[0075] At first, encoded data of a kth channel is modulated at a modulator 801 and then 2M modulation symbols are applied to a serial/parallel converter 802 at each transmission modulation symbol interval. Then, the serial/parallel converter 802 simultaneously outputs total M symbol pairs in parallel.
[0076] Each of the M symbol pairs, e.g., s k,0 and s k,1 , etc., is provided to an SCBC and spreading unit 803 wherein two vector signals s k,2m C (k,2m) +s k,2m+1 C (k,2m+1) and s* k,2m C (k,2m+1)s* k,2m+1 C (k,2m) are outputted from each of SCBC and spreading units 803 - 1 to 803 -M.
[0077] The output vector signals from the M SCBC and spreading units 803 - 1 to 803 -M are combined at combiners 804 a and 804 b for antenna paths composed of adders. Hence, an output from the combiner 804 a for the first antenna becomes
∑ m = 0 M - 1 ( s k , 2 m C ( k , 2 m ) + s k , 2 m + 1 C ( k , 2 m + 1 ) )
and an output from the combiner 804 b for the second antenna becomes
∑ m = 0 M - 1 ( s k , 2 m * C ( k , 2 m + 1 ) - s k , 2 m + 1 * C ( k , 2 m ) ) .
[0078] The outputs from the combiners 804 a and 804 b for the antenna paths are applied to channel combiners 805 a and 805 b to add to channel signals of other users. And then, the added signals are scrambled by multiplying by scrambling codes at scramblers 806 a and 806 b.
[0079] The outputs from the scramblers 806 a and 806 b are IFFT-transformed at IFFT units 807 a and 807 b , that is, the frequency domain signals are transformed into corresponding time domain signals, and then processed at parallel/serial converters 808 a and 808 b to obtain converted serial signals.
[0080] Thereafter, CP is inserted into each of the outputs from the parallel/serial converters 808 a and 808 b at CP inserters 809 a and 809 b ; and then the CP-inserted signals are amplified and converted into RF signals at IF/RF processors 810 a and 801 b to transmit them via corresponding antennas 811 a and 811 b.
[0081] FIG. 9 shows a view describing the concept of a transmission diversity method where one orthogonal code is assigned to each of arbitrary two users' channels in accordance with the present invention. That is, FIG. 9 presents a transmission diversity method in accordance with the present invention in case where one orthogonal code is assigned to an arbitrary user channel, i.e., the data transmission rate is R.
[0082] In this case, a transmitter of the present invention multiplexes modulation .symbols of arbitrary two channels whose data transmission rate is R at a multiplexer 901 , and then SCBC-encodes and spreads the multiplexed symbols using two orthogonal codes assigned to each channel at an SCBC and spreading unit 902 to transmit spread signals.
[0083] Details of the transmitter will be given below.
[0084] For example, if modulation signals of kth and uth users' channels are s k,0 and s u,0 at an arbitrary transmission interval, respectively, the multiplexed signal from the multiplexer 901 becomes s k,0 s u,0 which is then applied to the SCBC and spreading unit 902 , wherein the signal is SCBC-encoded and spread to orthogonal codes C (k) and C (u) assigned to each channel to output s k,0 C (k) +s u,0 C (u) to the first antenna and also provide s* k,0 C (u) −s u,0 C (k) to the second antenna.
[0085] With respect to the diversity transmission signals as described early, a mobile station receiver performs SCBC decoding and then takes only corresponding users' channel symbols excepting other users' channel symbols.
[0086] FIG. 10 is a circuitry diagram showing a configuration of one embodiment of a CDMA mobile station receiver with respect to the transmission diversity of the present invention, which represents a structure of a mobile station receiving end in case where the transmission diversity technique of the present invention is applied to the MC-CDMA base station transmitting end.
[0087] As shown in FIG. 10 , the MC-CDMA mobile station receiver of the invention comprises an antenna 1001 , an RF/IF processor 1002 , a CP remover 1003 , an FFT block 1004 , a descrambler 1005 , a despreader 1006 , a channel estimator 1007 , a channel equalization and SCBC decoder 1008 , a soft bit calculator 1009 , and a channel decoder 1010 . Each of the elements will be described below in detail.
[0088] A wireless signal is first received via the antenna 1001 and then amplified and converted into a baseband signal at the RF/IF processor 1002 .
[0089] The CP remover 1003 serves to remove CP from the output signal provided from the RF/IF processor 1002 , and the FFT 1004 transforms the time domain signal from the CP remover 1003 into a corresponding frequency domain signal. And then, the descrambler 1005 descrambles the frequency domain signal from the FFT 1004 .
[0090] The despreader 1006 despreads the descrambled signal to an orthogonal signal; and the channel estimator 1007 conducts channel estimation with respect to two wireless paths between two base station transmission antenna and mobile station reception antenna from the descrambled signal.
[0091] The channel equalization and SCBC decoder 1008 performs channel equalization and SCBC decoding using the outputs from the despreader 1006 and the channel estimator 1007 , that is, the despread reception symbols and channel estimation values to thereby recover a transmitted signal
[0092] Thereafter, the soft bit calculator 1009 receives the output from the channel equalization and SCBC decoder 1008 and calculates a soft bit value to be provided to the channel decoder 1010 .
[0093] And then, the channel decoder 1010 conducts the channel decoding and offers the decoded result to an upper layer.
[0094] Hereinafter, a more detailed description of the receiver will be provided.
[0095] For instance, if a transmitting end utilizes 2M orthogonal codes for kth user channel as shown in FIG. 8 (that is, if a data transmission rate is 2M that is twice a basic transmission rate R), the despreader 1006 of the mobile station receiver as shown in FIG. 10 outputs results that are despread to the 2M orthogonal codes assigned to the kth user channel every symbol interval.
[0096] Then, the channel equalization and SCBC decoder 1008 receives the 2M outputs from the despreader 1006 at each symbol interval and performs the SCBC decoding therefore.
[0097] In other words, in case where a wireless channel estimated value between the first transmission antenna (base station transmission antenna) and the mobile station reception antenna is α 0 , and a wireless channel estimated value between the second transmission antenna (base station transmission antenna) and the mobile station reception antenna is α 1 at an arbitrary symbol interval, if the symbol values despread by the orthogonal codes C (k+2m) and C (k+2m+1) (where m=0, 1, 2 , . . . , M−1) are r 2m and r 2m+1 , respectively, the output from the channel equalization and SCBC decoder 1008 may be as follows:
ŝ 2m =r 2m α* 0 +r* 2m+1 α 1
ŝ 2m+1 =r 2m α* 1 −r* 2m+1 α 0
where
m=0, 1, 2, . . . , M−1 Eq. (3)
[0098] On the other hand, if a transmitting end multiplexes and SCBC-encodes with respect to each of two users' channels to which only one orthogonal code is assigned and then transmits the results at the transmitter as shown in FIG. 9 , the despreader 1006 of the mobile station receiver as shown in FIG. 10 despreads to the orthogonal code C (k) assigned to the kth user channel and to the orthogonal code C (u) assigned to the uth user channel.
[0099] Then, using the two symbols r k and r u despread at the despreader 1006 and the output values α 0 and α 1 from the channel estimator 1007 , the channel equalization and SCBC decoder 1008 provides a signal obtained by taking the following equation 4 when the current mobile station is for the kth user channel and a signal derived by taking the following equation 5 when the current mobile state is for the uth user channel.
ŝ k =r k α* 0 +r* u α 1 Eq. (4)
ŝ u =r k α* 1 −r* u α 0 Eq. (5)
[0100] FIG. 11 a is a circuitry diagram depicting a configuration of one embodiment of a DS-CDMA diversity transmitter using SCBC in case where 2M codes are assigned to an arbitrary user in accordance with the present invention, and FIG. 11 b is a circuitry diagram illustrating a configuration of the SCBC and spreading unit of the invention shown in FIG. 11 a.
[0101] The basic concept of the DS-CDMA diversity transmitter (base station transmitter) as shown in FIGS. 11 a and 11 b is the same as that of the MC-CDMA as shown in FIG. 8 except that the spreading process is carried out on the time axis. Details thereof will be presented hereinafter.
[0102] Firstly, encoded data every channel is modulated at a modulator 1101 and then 2M modulation symbols are applied to a serial/parallel converter 1102 at each transmission modulation symbol interval. Then, the serial/parallel converter 1102 simultaneously outputs a total M number of symbol pairs in parallel. Each of the M symbol pairs, e.g., s k,0 and s k,1 , etc., is provided to an SCBC and spreading unit 1103 wherein two vector signals are outputted from each of SCBC and spreading units 1103 - 1 to 1103 -M. For example, an (m+1)th SCBC and spreading unit 1103 -(m+1) included in the SCBC and spreading unit 1103 provides s k,2m C (k,2m) +s k,2m+1 C (k,2m+1) and s* k,2m C (k,2m+1 −s* k,2m+1 C (k,2m) (see FIG. 11 b ).
[0103] The output vector signals from the M SCBC and spreading units 1103 - 1 to 1103 -M are added at adders 1104 a and 1104 b for each antenna path. Hence, an output from the adder 1104 a for a first antenna path becomes
∑ m = 0 M - 1 ( s k , 2 m C ( k , 2 m ) + s k , 2 m + 1 C ( k , 2 m + 1 ) )
and an output from the adder 1104 b for a second antenna path becomes
∑ m = 0 M - 1 ( s k , 2 m * C ( k , 2 m + 1 ) - s k , 2 m + 1 * C ( k , 2 m ) ) .
[0104] The outputs from the adders 1104 a and 1104 b are applied to channel combiners 1105 a and 1105 b to add to channel signals of other users. And then, the added signals are scrambled by multiplying by scrambling codes at scramblers 1106 a and 1106 b.
[0105] The outputs from the scramblers 1106 a and 1106 b are amplified and converted into RF signals at IF/RF processors 1107 a and 1107 b to transmit them via corresponding antennas.
[0106] As can be seen from the drawing, since the DS-CDMA base station transmitter performs the spreading process on the time axis, it doesn't include the IFFTs 807 a and 807 b , the parallel/serial converters 808 a and 808 b , and the CP inserters 809 a and 809 b , which are involved in the MC-CDMA as shown in FIG. 8 .
[0107] Meanwhile, a description will be given below in detail with respect to the (m+1)th SCBC and spreading unit 1103 -(m+1) in the SCBC and spreading unit 1103 .
[0108] The outputs from the serial/parallel converter 1102 , s k,2m and s k,2m+1 , are provided to an SCBC encoder 11031 ; and the outputs therefrom are then spread by multiplying by orthogonal codes at a spreader 11032 . Lastly, outputted from an adding unit 11033 are a baseband signal to be s k,2m+1 C (k,2m) +s k,2m+1 C (k,2m+1) to be transmitted via a first transmission antenna and a baseband signal s* k,2m C (k,2m+1) −s* k,2m+1 C (k,2m) to be transmitted via a second transmission antenna.
[0109] As a result, the present invention allows the antenna diversity to be conducted within one symbol interval, thereby improving the performance of system in wireless channel environments where Doppler effect exists, compared to a conventional STBC transmission diversity method which makes the antenna diversity performed over two symbol intervals.
[0110] The method of the present invention as mentioned above may be implemented by a software program and stored in a computer-readable storage medium such as CD-ROM, RAM, ROM, floppy disk, hard disk, optical magnetic disk, etc. This process may be readily carried out by those skilled in the art; and therefore, details of thereof are omitted here.
[0111] The present application contains subject matter related to Korean patent application No. 2005-48940, filed with the Korean Intellectual Property Office on Jun. 8, 2005, the entire contents of which are incorporated herein by reference.
[0112] While the present invention has been described with respect to the particular embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.
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Provided are a space code block coding and spreading apparatus and method for transmission diversity, a Code Division Multiple Access (CDMA) diversity transmitter using it, and a CDMA mobile station receiver for receiving a transmission diversity signal, which are capable of improving the performance of system in wireless channel environments by allowing a transmission diversity to be made within one symbol interval in a CDMA communication system. The inventive space code block coding and spreading apparatus for transmission diversity in a CDMA communication system, comprises an encoder for generating a predetermined number of different transmission data with respect to a plurality of modulation symbols inputted during one modulation symbol interval, an orthogonal code generator for producing orthogonal codes, a spreader for spreading each of the transmission data generated from the encoder using the orthogonal codes generated from the orthogonal code generator, and a combining unit for combining the transmission data spread at the spreader to provide combined data for each transmission antenna path so that a transmission diversity is made within one modulation symbol interval.
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CROSS-REFERENCE TO PROVISIONAL APPLICATION(S)
This application claims the benefit of U.S. Provisional Application No. 61/342,283, filed Apr. 12, 2010.
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to fluid handling and, more particularly, to a portable fuel can and nozzle assembly with pressure relief.
A number of additional features and objects will be apparent in connection with the following discussion of the preferred embodiments and examples with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
There are shown in the drawings certain exemplary embodiments of the invention as presently preferred. It should be understood that the invention is not limited to the embodiments disclosed as examples, and is capable of variation within the scope of the skills of a person having ordinary skill in the art to which the invention pertains. In the drawings,
FIG. 1 is a perspective view of a portable fuel can and nozzle assembly with pressure relief in accordance with the invention;
FIG. 2 is an enlarged-scale perspective view of fuel nozzle assembly in isolation;
FIG. 3 is a partial sectional view taken along line in FIG. 2 ;
FIG. 4 is a front elevational view thereof;
FIG. 5 is an enlarged scale perspective view of detail V-V in FIG. 3 ;
FIG. 6 is a partial sectional view comparable to FIG. 2 except showing an alternate embodiment of under-pressurization relief;
FIG. 7 is an enlarged scale elevational view of detail VII-VII in FIG. 6 ; and
FIG. 8 is a partial sectional view taken along line VIII-VIII in FIG. 7 .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1 and 3 show a combined portable fuel can 20 and nozzle assembly 22 with pressure relief in accordance with the invention.
Preferably the portable fuel can 20 provides just a single opening which serves both re-fill and pour functions. This opening is surrounded by a threaded neck. The nozzle assembly 22 screws onto this threaded neck. With general reference to FIG. 1 through 5 , the nozzle assembly 22 serves a number of functions. A non-exclusive list includes, without limitation, the following.
1—It is a cap 30 (eg., to cover the can 20 's re-fill/pour opening and generally seal vapors inside the contained volume inside the combined nozzle assembly 22 and portable fuel can 20 ). 2—It is a spout 32 (eg., to dispense fuel into a target, such as a tank of a vehicle or the like, which is not shown). 3—It has an automatically CLOSED main valve 34 , so that during non-use, the main valve 34 is CLOSED and the vapors are generally sealed inside the contained volume of the can/nozzle assembly 20 / 22 . 4—It has a manual operator (eg., thumb button 36 is preferred) so that during use, a user can selectively OPEN the main valve 34 and pour, with precise control. 5(a)—During pouring operations, it provides vacuum venting or, that is, the admission of air (or vapors and/or admixtures thereof) into the contained volume as the fuel level drains in the can 20 , and in order to prevent the walls of the can 20 from collapsing or else choking off the pour. 5(a)—During pouring operations, it provides for more than mere vacuum venting, it provides for gaseous exchange:—ie., the can 20 while emptying is suctioning out the gases, (eg., generally, ‘vapor,’ likely, a mix of true vapor diluted by air) that are being flushed out by the rising fuel level in the tank-being-filled. 6—It provides automatic overflow cutoff. 7—It and/or the can 20 or else both in combination might provide a handle 28 or handles 38 for the user. 8—During non-use, in order to prevent damage due to over-pressurization, it provides for over-pressurization self-relief and cracks a seal 46 , 56 to allow escape of vapors until the pressure differential between vapors in the can 20 and ambient are within an acceptable range (eg., over-pressurization relief). 9—During non-use, in order to prevent damage due to under-pressurization, it provides for under-pressurization self-relief and cracks a vacuum-relief seal 40 or 97 to allow admission of air until the pressure differential between the vapors in the can 20 and ambient are again within an acceptable range (eg., a vacuum-relief valve 40 or 97 , and in contrast to vacuum venting through inlet port 72 during pouring).
The nozzle assembly 22 is accompanied by a retaining collar 42 . The retaining collar 42 actually screws onto the threaded neck of the can 20 in order to seal the re-fill/pour opening with the nozzle assembly 22 . The collar 42 screws tight onto the neck, forcing an air-tight seal between mating flanges of the neck and the nozzle assembly 22 . Preferably the fuel can 20 , the collar 42 , and most of the components of the nozzle assembly 22 are produced out of plastic materials (wherein, spring steel is preferably used to make a spring 44 and elastomeric materials are preferably used to make an O-ring 46 , grommet serving as a ring seal 78 , umbrella valve 40 and/or O-ring 97 serving as the under-pressurization seals).
The nozzle assembly 22 includes a hollow T-shaped cap 30 , a pour spout 32 , a main valve 34 , and thumb button 36 to manually operate the main valve 34 .
The hollow T-shaped cap 30 has a bottom-ported cylindrical stem 50 (ie., which is closed across the top) with one reduced-size ported arm 52 extending rearward and another reduced-size ported arm 54 extending forward on about the same linear axis as the rearward arm 52 . The bottom-ported cylindrical stem 50 and the reduced-size ported arm 54 that extends forward both include interior volume that is part of the greater contained volume of the can/nozzle assembly 20 / 22 as a whole.
The rear ported arm 52 essentially serves as a receiver for the thumb button 36 . More particularly, it is preferred if the rear ported arm 52 essentially serves as a hollow cylindrical track for sliding reciprocation of the thumb button 36 . The forward ported arm 54 serves both as a valve seat 56 as well as a nipple on which the spout 32 is affixed.
The spout 32 comprises a hollow outer sleeve 58 and a hollow inner sleeve 62 . The hollow inner sleeve 62 is, in other words, the vent intake tube 62 . The inner and outer sleeves 58 and 62 are fixed together by a pair of flanking webs 66 to define an annular pour conduit 64 . The vent intake tube 62 extends between inner and outer open ends 68 and 72 and serves as the vacuum venting conduit during the pour. The outer open end 72 serves as the vent intake port. During pouring, make-up gases are suctioned into portable fuel can 20 by way of the vent intake port 72 . If the pour is into, say, an open container such as a coffee can, then the make-up gases are going to be air for the most part. At the same time during the pour, fuel pours out (needless to say) through the annular pour conduit 64 between the inner and outer sleeves 68 and 72 (fuel pouring out is not shown).
If the spout 32 is disposed into a confined container, say, the neck of a fuel tank (neither tank nor neck thereof are shown), there will actually be an exchange of gases. That is, the nozzle assembly 22 will suction in through the vent intake port 72 of the spout 32 the needed make-up gases (ie., generally a mixture of ‘true’ fuel vapor and air) for the emptying can 20 from the pushed-out gases needing to escape from the filling tank. That is, the pushed-out gases from the filling tank will be suctioned into the emptying can 20 to make up for the increase in volume in the can 20 for gases due to the fuel dispensed out therefrom.
The main valve 34 comprises a tubular valve stem 74 that extends between a closed end affixed to the thumb button 36 and an open end that telescopes over the spout 32 's vent intake tube 62 at the inner open end 68 thereof and forms a sliding seal with the vent intake tube 62 . The valve stem 74 's open end flares out as a conic valve member 76 . As stated above, the forward ported arm 54 serves in part as the valve seat 56 .
FIG. 4 shows the valve member 76 closed against the valve seat 56 , to form an air tight seal. The tubular valve stem 74 inserts through a ring seal 78 for it in the rearward ported arm 52 . A compression spring 44 compressible between the thumb button 36 and a flange surface surrounding the ring seal 78 on the valve stem 74 automatically forces the valve member 76 shut against the valve seat 56 .
Hence the valve seat 56 and valve member 76 form one air tight seal. The ring seal 78 around the valve stem 74 forms another. Thus the contained gaseous gases (and the liquid fuel) are sealed inside the combined contained volume of the can 20 ′ and nozzle assembly 22 . It can be discerned that the valve stem 74 has ventilation apertures 82 formed in the sidewall thereof rear of the ring seal 78 .
In use, a user tips the spout 32 down until liquid fuel fills the forward ported arm 54 until backed up against the valve member 76 . When the user depresses the button 36 , the valve stem 74 is thrust forward until the ventilation apertures 82 slide forward of the ring seal 78 and into the (until now) sealed interior volume of the can 20 and nozzle assembly 22 . The T-shaped cap 30 has a pair of flanking ears 38 serving as handles and/or finger rests for the middle and index finger of the hand used to depress the button 36 with the thumb thereof. The seal is broken at the valve seat 56 . With the same thrust of the valve stem 74 , the ventilation apertures 82 are inside the ring seal 78 . Liquid fuel flows out across the valve seat 56 . The vacuum venting of make-up air or vapors are suctioned into the vent intake port 72 and dispersed into the combined interior volume of the can 20 and nozzle assembly 22 via the ventilation apertures 82 in the valve stem 74 .
When the user lets off the button 36 , the compression spring 44 automatically drives the main valve 34 to shut, stopping the pour of liquid fuel. Alternatively, if the fuel level of the tank-to-be-filled floods to the level where the fuel level submerges the vent intake port 72 , then the pour of liquid fuel is likewise automatically shut-off by the virtue of choking off the vent intake port 72 from the suctioning in of make-up gases (air and/or vapors).
The foregoing has described the conditions of the can/nozzle assembly combination 20 / 22 being sealed and vented (and back to being sealed again) in connection with pouring. In connection with long non-use during storage or transport, there is further interest in the pressure differential between ambient and the vapors sealed in the closed can/nozzle assembly 20 / 22 . The pressure differential can go either way. That is, the vapors contained inside the can/nozzle assembly 20 / 22 can be either over-pressurized relative ambient, or under-pressurized.
FIG. 3 shows better that, the combination can 20 and nozzle assembly 22 in accordance with the invention is provided with self-relief of over-pressurization by the following design. The compression spring 44 is designed to yield if the pressure against the back of the valve member 76 exceeds a design set-point. That is, if the pressure inside the can 20 and nozzle assembly 22 exceeds the design set-point, the vapors are permitted to leak out past the cracked-open valve member 76 . It is preferred to leak vapors out of the over-pressurized can 20 rather than keep the vapors corked inside until the over-pressurization damages the can 20 's sidewalls and/or components of the nozzle assembly 22 . Hence, among its other functions, the main valve 34 also functions as an over-pressure relief valve.
FIGS. 4 and 5 show better that, the combination can 20 and nozzle assembly 22 in accordance with the invention is provided with self-relief of under-pressurization by a vacuum relief valve 40 . This particular design includes without limitation a push-in version of an elastomeric umbrella valve 40 . The umbrella valve 40 functions as a one-way valve. The bottom-ported cylindrical stem 50 of the T-shaped cap 30 has a pair of apertures 84 and 86 formed in its sidewall, one larger than the other. The umbrella valve 40 comprises a shaft 92 extending between a barbed end 94 and an annular umbrella canopy 96 . The shaft 92 gets pushed into the larger hole 84 (eg., the mounting hole), barbed end 94 first, from inside the T-shaped cap 30 . The smaller hole 86 is situated close enough such that the annular canopy 96 of the umbrella valve 40 laps over this hole, the vacuum-relief port 86 . The push-in valve 40 's shaft 92 forms a permanent seal with the mounting hole 84 for it in the cap 30 's sidewall. In contrast, the push-in valve 40 's annular canopy 96 forms merely a temporary seal over the vacuum-relief port 86 under conditions of over-pressurization or light under-pressurization. When the under-pressurization exceeds a design set-point value, the elastomeric canopy 96 cracks the seal over the vacuum-relief port 86 , allowing an intake of fresh air, and hence preventing the can 20 's sidewall from crushing in on itself.
Optionally, the vacuum-relief valve 40 can be re-located from being mounted on the nozzle assembly 22 to instead on the portable fuel can 20 .
FIGS. 6 through 8 show an alternate embodiment in which the combination of the can 20 (not shown in these views) and nozzle assembly 22 in accordance with the invention is provided with self-relief of under-pressurization by a vacuum relieving (or vacuum breaking) O-ring 97 . The relief valve 40 is omitted in these views. The vacuum breaking O-ring 97 functions as a one-way valve. As FIG. 6 shows better, the vacuum breaking O-ring is encircled around hollow valve stem 74 of main valve 34 . When the main valve 34 is in the closed position, the hollow interior of the valve stem 74 is not in communication for vapor exchange with the vapors inside the greater confined volume of the can/nozzle assembly 20 / 22 . Instead, the hollow interior of the valve stem 74 is open to the atmosphere at vent intake port end 72 and also as well at ventilation apertures 82 .
Again, the vacuum breaking O-ring 97 snugly/tightly encircles the valve stem 74 . The valve stem 74 is formed with two pair of retention seats 98 . The retention seats 98 comprise nodes (or bumps) of material extending out of the sidewall of the valve stem 74 .
By way of non-limiting example, one pair of retention seats 98 are illustrated as flanking the O-ring 97 at the twelve o'clock position of the valve stem 74 . The other pair of retention seats 98 are illustrated as flanking the O-ring 97 at the six o'clock position of the valve stem 74 . The ordinarily skilled artisan would routinely understand how to routinely vary the illustrated design into numerous routine variations of what is drawn in the drawing figures, and still be guided by the present disclosure.
FIGS. 7 and 8 together show the coordinated features of the vacuum-breaking O-ring 97 and the retention seats 98 . FIG. 8 shows that the pair of retention seats 98 at the twelve o'clock position flank a pin-hole sized 99 aperture serving as a vacuum-breaking port 99 .
The retention seats 98 are only circumferentially formed around the circumference of the valve stem 74 by a minuscule amount. The six o'clock seats 98 cooperate more than adequately with the twelve o'clock seats 98 to retain the O-ring 97 in the preferred axial station along the axis of the valve stem 74 . The twelve o'clock seats 98 flank the preferred and sole vacuum-breaking port 99 . The outlet of the vacuum-breaking port 99 in the sidewall of the valve stem 74 is positioned at the bottom of the trough between the twelve o'clock seats 98 .
When the gases in the can 20 are pressurized in equilibrium with ambient, the vacuum-breaking O-ring 97 seats to form a seal over the vacuum-breaking port 99 as pinched (seated) among (i) the twelve o'clock seats 98 and (ii) the trough therebetween being the sidewall of valve stem 74 between those twelve o'clock seats 98 . Hence there is not any under-pressurization condition, nor any under-pressurization relief.
When the gases in the can 20 are over-pressurized relative to ambient, the vacuum-breaking O-ring 97 is compressed thereby to form even a tighter seal over the vacuum-breaking port 99 .
When the gases in the can 20 are under-pressurized by a depressed amount selected by design, the vacuum-breaking O-ring 97 yields to leakage into the greater contained volume of the can/nozzle assembly 20 / 22 , and hence intake of air into the greater contained volume of the can/nozzle assembly 20 / 22 . The air supply fills the hollow interior of the valve stem 74 either and/or both through the vent intake port 72 and/or ventilation apertures 99 .
In all the text herein of this patent document, the term “vapor” has any of the following meanings according to context:—1—fuel vapor, 2—admixture of fuel vapor and air, and/or 3—gases or gaseous mixtures in general, whether clean or entrained.
The invention having been disclosed in connection with the foregoing variations and examples, additional variations will now be apparent to persons skilled in the art. The invention is not intended to be limited to the variations specifically mentioned, and accordingly reference should be made to the appended claims rather than the foregoing discussion of preferred examples, to assess the scope of the invention in which exclusive rights are claimed.
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A nozzle assembly for a portable fuel can has the following. A cap provision for generally sealing vapors inside a contained volume inside the combined nozzle assembly and portable fuel can. A spout to dispense liquid fuel. A main valve for the liquid fuel which automatically closes in the absence of manual operation. A manual operator for manually and selectively opening the main valve. Porting providing vacuum venting whereby gases are admitted into the contained volume as the liquid fuel level pours out of the can, whereby the vacuum venting allows for gaseous exchange between the can as liquid fuel empties therefrom and the target container liquid-fuel fills in and flushes out gases due to the rising fuel level therein. Wherein the vacuum venting comprising and intake port disposed to provide automatic overflow cutoff. At least one over-pressurization relief break, and at least one under-pressurization relief break.
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OBJECT OF THE INVENTION
[0001] The present invention belongs to the technical field of microalgae production. Specifically, it falls within the area of culture systems designed for the mass production of microalgae under external conditions.
[0002] The object of the patent is an optimised microalgae culture system that comprises a shallow-depth culture container, a rotation system designed for the generation of light-darkness cycles and re-suspension, which maximises the photosynthetic efficiency of the microalgae and homogenises the nutrients supplied, such that the microalgae may adequately grow in all the areas of the photobioreactor, a gas exchange and temperature control system, which makes it possible to control and maintain the culture parameters under the optimal microalgae growth conditions, a filtration and self-cleaning system, an energy control and saving system, which makes it possible to maintain the desired conditions with the lowest energy expenditure, and a cover system, which filters ultraviolet radiation and makes it possible to control contaminations, the temperature and the evaporation. All this with low investment, minimum energy consumption and high culture efficiency.
BACKGROUND OF THE INVENTION
[0003] Microalgae are proving to be of great utility because they present a large number of beneficial applications in various different areas, such as wastewater treatment, production of biofuels, food for humans and animals, and the obtainment of high-value chemical products. Microalgae cultures may reach productivities that are much higher than those of traditional cultures, leading to a greater CO 2 fixation and a larger quantity of biomass produced. Moreover, microalgae cultures have lower water requirements and do not compete with traditional cultures, since they do not need fertile soil or potable water.
[0004] In order to obtain an optimal profitability in large-scale microalgae production projects, large areas, in addition to sufficiently large industrial facilities, are needed in order to justify the necessary investments. Microalgae production systems primarily include two differentiated classes: closed systems and open systems. Closed systems are characterised in that they insulate the fluid from the external environment and are less exposed to disturbances, whereas open systems are characterised in that they have a greater interaction with or exposure to the environment and are more dependent on the conditions thereof.
[0005] Microalgae production systems are equipped with devices designed to extract the microalgae once they are generated; this is what is called “harvesting”. They are also equipped with devices designed for the inclusion of new culture media, where culture medium is understood to mean the set of nutrients dissolved in water which the microalgae need, as well as for the stirring and reduction of concentration gradients, the elimination of oxygen and the absorption of carbon dioxide in the culture medium.
[0006] In microalgae production systems, the following factors must be taken into consideration in order to achieve the maximum yield:
Oxygen at high concentrations may be toxic for the microalgae, especially when there is a high solar radiation, Microalgae perform photosynthesis and, therefore, should have sufficient light available, although an excess of light may be harmful. Microalgae should not remain in permanent darkness, and an optimal light exposure frequency makes it possible to optimise the productivity, The nutrients supplied should be homogenised, such that the microalgae may grow in all the areas of the system, The CO 2 should be distributed throughout the entire culture system, such that the microalgae may fixate this CO 2 , The decanting of microalgae in dead zones of the culture systems should be avoided, since, in addition to entailing a loss of productivity, because these cells do not have access to light, the decanted cells may be a contamination focus, The culture systems should be kept clean, in order to prevent contaminations that may affect the growth of the microalgae, The microalgae cultures should be kept within an appropriate temperature range, in order to optimise the productivity and prevent cell death caused by cold or excessive heat.
[0014] The microalgae culture systems known by the applicant are either tubular systems that may be closed or large bags, preferably made of a plastic material, which present a high energy consumption to obtain an acceptable yield in microalgae production.
DESCRIPTION OF THE INVENTION
[0015] The present invention relates to a high-productivity, low-investment microalgae culture system under external conditions optimised for microalgae production, which makes it possible to generate light-darkness cycles in the system, the cleaning and maintenance thereof under optimal production conditions, with minimum energy consumption, i.e. with a high efficiency.
[0016] The culture system comprises:
a shallow-depth culture medium container, where shallow depth is understood to mean a tank wherein the ratio between the height “h” of the culture medium, in m, and the surface area “A” of the base of the container, in m 2 , meets the condition that
[0000]
h
A
4
<
0.12
.
This characteristic makes it possible to work with high cellular concentrations, since there is less contamination and the “downstream” cost is reduced; moreover, there is a low investment cost, since no support structures are required, and there is also easy climbing.
a rotation system equipped with at least some rotating means.
a culture medium that may be vertically displaced by the rotating means, to generate a turbulent regime in the culture medium,
where the rotating means are preferably composed of a set of rotating blades. These blades may have the following functions:
They may be blades that generate light-darkness cycles in the culture medium. They produce movement in the culture, thereby preventing the stratification thereof, increasing its homogeneity and, consequently, considerably increasing the productivity. This system gives priority to the vertical movement, thereby minimising the energy consumption, in addition to being easily climbable by increasing the number and length of the blades, and/or sweep blades, the mission whereof is to re-suspend the algae deposited and clean potential contaminations at the bottom of the container. This re-suspension makes it possible to keep the entire cell population under continuous growth, generating a greater quantity of biomass and, consequently, increasing the productivity. The self-cleaning system makes it possible to increase the number of working days and simultaneously reduce the labour costs necessary for the operation thereof, and/or blades equipped with deflection means the mission whereof is to adapt the movement of the fluid, decreasing the mixing times, favouring the homogeneity of the system and, consequently, increasing the efficiency and productivity thereof.
The culture system further comprises a CO 2 fixation and O 2 desorption system for the simultaneous transfer of both matter and heat. The CO 2 fixation and O 2 desorption system preferably has the shape of a pit the bottom whereof contains diffusers that supply CO 2 or mixtures of CO 2 with other combustion gases in order to carry inorganic carbon, and/or air in order to desorb the excess O 2 that may accumulate. These diffusers are high-efficiency diffusers, in order to achieve a high matter transfer coefficient whilst minimising the energy consumption. This same pit contains a heat exchanger that makes it possible to control the temperature of the culture medium or the thermostatting thereof. This pit may be integrated in the interior of the culture medium container ( 1 ) or in the exterior thereof, preferably buried. In the latter case, a pump is used to force passage of the entire culture medium through the CO 2 fixation, O 2 desorption and thermostatting system.
[0026] The culture system further comprises a surface filtration system that makes it possible to remove potential contaminations and foreign elements with a lower density than the culture medium and a larger size than the microalgae. No additional labour or maintenance is required, which increases the cleanliness and productivity, since shadows, i.e. lack of irradiance, are avoided and the hygiene of the culture is improved.
[0027] The culture system further comprises an energy control and saving system that records pluviometric, radiation, pH, temperature and dissolved oxygen data and acts on the injection of CO 2 , the air supply, the rotation system and the system cover. This energy control and saving system makes it possible to maintain the optimal working conditions with the lowest energy consumption and hardly any labour or supervision.
[0028] The culture system further comprises a transparent cover system. The purpose of the cover is to better control the temperature, prevent contaminations, filter ultraviolet and infrared radiation, and reduce the water consumption by controlling the evaporation thereof. It is possible to place a central axis perpendicular to the flat culture medium container, whereon the cover is supported, descending down to the perimeter thereof. This system is very economical due to the absence of complicated structures.
[0029] The culture system further comprises a water replacement device that may operate alternatively or jointly with the cover system to introduce water into the culture medium container and thus keep the volume of water at the required levels. The culture system further comprises a harvesting system designed for the extraction of the microalgae once the growth process thereof is completed, and a culture medium supply system.
DESCRIPTION OF THE DRAWINGS
[0030] In order to supplement the description, and contribute to a better understanding of the characteristics of the invention, a set of drawings is attached as an integral part of said description, for illustrative, non-limiting purposes. The following has been represented:
[0031] FIG. 1 .—Shows the microalgae culture system under external conditions of the present invention with a first embodiment of the CO 2 fixation and O 2 desorption system.
[0032] FIG. 2 .—Shows the microalgae culture system under external conditions of the present invention with a second embodiment of the CO 2 fixation and O 2 desorption system.
[0033] FIG. 3 .—Shows the microalgae culture system under external conditions of the present invention with a third embodiment of the CO 2 fixation and O 2 desorption system.
[0034] FIG. 4 .—Shows the microalgae culture system under external conditions of the present invention with a fourth embodiment of the CO 2 fixation and O 2 desorption system.
[0035] FIG. 5 .—Shows a profile view of the blades that generate the light-darkness cycles in the culture medium.
[0036] Description of the Elements that Make Up the System:
[0037] Element 1 represents the culture medium container.
[0038] Element 2 represents the rotating blades that allow for the generation of light-darkness cycles.
[0039] Element 3 represents the rotating blades that sweep and re-suspend the culture.
[0040] Element 4 represents the rotating blades, equipped with deflectors capable of modifying the flow of the fluid inside the culture medium container.
[0041] Element 5 represents a schematic view of the carbon dioxide fixation and oxygen desorption system placed inside the area delimited by the culture medium container ( 1 ).
[0042] Element 6 represents a schematic view of the surface filtration system.
[0043] Element 7 represents a schematic view of the energy control and saving system that makes it possible to optimise the energy consumption.
[0044] Element 8 represents a schematic view of the cover system.
PREFERRED EMBODIMENT OF THE INVENTION
[0045] In light of the figures, we describe several preferred embodiments of the culture system that comprises a shallow-depth, flat culture medium container with a circular base ( 1 ), where shallow depth is understood to mean a container wherein the ratio between the height “h” of the culture medium and the surface area “A” of the base of the container meets the condition that
[0000]
h
A
4
<
0.12
,
[0000] a rotation system that comprises at least rotating means designed to vertically displace the culture medium, thereby generating a turbulent regime, where these rotating means are preferably composed of a set of rotating blades ( 2 ) around a vertical central axis of the container for the generation of light-darkness cycles.
[0046] The rotation system further comprises a set of sweep blades ( 3 ) that clean the container surfaces and a set of deflector blades ( 4 ), or blades equipped with deflection means, the mission whereof is to adapt the movement of the fluid, thereby decreasing the mixing times.
[0047] The culture system further comprises one or several carbon dioxide fixation and oxygen desorption systems ( 5 ), which further comprise thermostatting means, as well as a surface filtration system ( 6 ), an energy control and saving system, which makes it possible to optimise the energy consumption ( 7 ), and a cover system ( 8 ).
First Preferred Embodiment
[0048] In a first preferred embodiment, shown in FIG. 1 , the carbon dioxide fixation and oxygen desorption system ( 5 ), which further comprises thermostatting means, is located inside the area delimited by the culture medium container ( 1 ), extends from the centre to the periphery thereof along the entire radius and has the shape of a pit. The carbon dioxide fixation and oxygen desorption system ( 5 ) comprises a gas injection system placed on the lower part of the pit, which comprises diffusers that inject air, CO 2 or mixtures of CO 2 with other combustion gases in order to supply inorganic carbon and/or air to desorb the excess O 2 that may accumulate.
[0049] The gas injection system further comprises a gas flow rate regulator valve that makes it possible to regulate the desorption of oxygen from the culture medium, since oxygen at high concentrations is toxic for the microalgae. This same pit houses an exchanger that makes it possible to control the temperature of the culture medium.
[0050] The profile of the rotating blades ( 2 ) designed for the generation of light-darkness cycles has the shape of a fin, and the attack edge of the profile of the rotating blades ( 2 ) is closer to the bottom of the circular-base container ( 1 ) than the outlet edge of said rotating blades ( 2 ) designed for the generation of light-darkness cycles, where the attack edge is not on the same vertical line as the outlet edge. This configuration makes it possible to increase the turbulence in the culture medium downstream from the blades, thereby favouring the displacement of the culture medium in the vertical direction.
[0051] Therefore, the culture system performs several functions simultaneously:
[0052] to efficiently desorb the O 2 ,
[0053] to efficiently fixate the CO 2 ,
[0054] to generate light-darkness cycles with a low energy cost,
[0055] to thermostat the culture medium,
[0056] to prevent the microalgae from depositing,
[0057] to homogenise the nutrients,
[0058] to homogenise the available CO 2 .
Second Preferred Embodiment
[0059] In a second preferred embodiment, shown in FIG. 2 , the carbon dioxide fixation and oxygen desorption system ( 5 ), which further comprises thermostatting means, is located inside the area delimited by the culture medium container ( 1 ), at the centre of the tank, and has the shape of a pit. The carbon dioxide fixation and oxygen desorption system ( 5 ) comprises a gas injection system located on the lower part of the pit, which comprises diffusers that inject air, CO 2 or mixtures of CO 2 with other combustion gases in order to supply inorganic carbon and/or air to desorb the excess O 2 that may accumulate.
[0060] The rest of the elements of the culture system are those described in the first preferred embodiment and perform the same functions simultaneously.
Third Preferred Embodiment
[0061] In a third preferred embodiment, shown in FIG. 3 , the carbon dioxide fixation and oxygen desorption system ( 5 ), which further comprises thermostatting means, is located outside the area delimited by the culture medium container ( 1 ) and is arranged in the shape of a pit below the base of the container ( 1 ). The carbon dioxide fixation and oxygen desorption system ( 5 ) comprises a gas injection system located on the lower part of the pit which comprises diffusers that inject air, CO 2 or mixtures of CO 2 with other combustion gases to supply inorganic carbon and/or air to desorb the excess O 2 that may accumulate.
[0062] The rest of the elements of the culture system are those described in the first preferred embodiment and perform the same functions simultaneously.
Fourth Preferred Embodiment
[0063] In a fourth preferred embodiment, shown in FIG. 4 , the carbon dioxide fixation and oxygen desorption system ( 5 ), which further comprises thermostatting means, is located outside the area delimited by the culture medium container ( 1 ), at the level of the base of the container ( 1 ). The carbon dioxide fixation and oxygen desorption system ( 5 ) comprises a gas injection system located on the lower part of the carbon dioxide fixation and oxygen desorption system ( 5 ) which comprises diffusers that inject air, CO 2 or mixtures of CO 2 with other combustion gases to supply inorganic carbon and/or air to desorb the excess O 2 that may accumulate.
[0064] In this case, the system is equipped with a pump that allows for the exit of the culture from the container ( 1 ) towards the CO 2 fixation and O 2 desorption system ( 5 ), and the return hereto.
[0065] The rest of the elements of the culture system are those described in the first preferred embodiment and perform the same functions simultaneously.
[0066] Below we will describe in detail the auxiliary systems that may be a part of the culture system described in any of the aforementioned embodiments.
[0067] 1. A cover system that makes it possible to convert the culture system into a closed system, where the height of the rotating vertical axis protrudes from the upper edge of the culture container ( 1 ), such that a cover is fixed to a rotating vertical axis and covers the entire upper perimeter of the culture container, transforming it into a greenhouse, the cover being preferably made of plastic. Preferably, it may also be made of a transparent plastic that filters ultraviolet and/or infrared radiation.
[0068] Thus, this cover system makes it possible to convert the culture system into a closed system, with the following added advantages:
External contamination is prevented. The culture temperature may be kept more stable against external variations. Certain wavelengths may be filtered by installing a cover made of a given material. It is possible to control the evaporation; therefore, less water is lost and the sustainability of the system increases.
[0073] 2. An energy control and saving system that optimises the energy consumption as a function of the concentration of O 2 and the pH of the culture medium, which comprises one or several of the following elements:
One or more pH meters. One or more oxygen meters. A rotational speed variator for the system.
[0077] The energy control and saving system comprises a control device that receives a signal of the concentration of oxygen dissolved in the culture. If this value is greater than a pre-determined value, it acts on the desorption system, causing an increase in the transfer of matter and the consequent decrease in the level of dissolved oxygen.
[0078] Alternatively, the energy control and saving system may receive two or more signals of the pH of the culture. One of these two measured signals is located far from the point of injection of the carbon dioxide and is used to regulate the dosage of CO 2 . The other measured signal, located considerably far from the first measured signal, indicates the homogeneity of the system. If the difference between the reading values of the two measurements is greater than a previously set value, the system acts on the rotational speed variator and on the desorption and cleaning system in order to improve the mixing inside the culture system and, consequently, the homogeneity thereof.
[0079] A typical situation where there may be substantial differences in the pH of different areas of the container ( 1 ) occurs when new culture medium is added to the container ( 1 ), since it is added at a specific point. Therefore, in this case, different pHs are detected in different areas and the system acts to reduce the mixing time of the entire culture. When the culture is homogenised, preventing differences in the concentration of CO 2 , there is an energy saving, because the rotation of the rotating axis is regulated as a function of the needs. In this way, the energy saving system makes it possible to operate the rotation system such that it is efficient as a function of the different variables associated with microalgae production.
[0080] 3. A water replacement system that may operate alternatively or jointly with the cover system to introduce water into the culture container ( 1 ), and thus keeps the volume of water at optimal levels, since in open systems water is continuously evaporated.
[0081] This water replacement system comprises the following elements:
Level meter, Water impeller
[0084] When the level meter detects a level of liquid in the culture container ( 1 ) that is below a certain value, the water impeller is acted on in order to make water go into the container ( 1 ) until the necessary level is completed. Preferably, the level meter comprises a buoy or float which, when the level of liquid in the container ( 1 ) decreases, acts as a mechanical switch, and acts on an electrovalve that allows for the passage of water to refill the container ( 1 ) with water.
[0085] 4. A harvesting system designed for the extraction of the microalgae once the growth process is completed, as well as cleaning systems for the bottom and/or walls of the container ( 1 ), and culture medium injection systems.
[0086] The harvesting system comprises a pump that makes it possible to extract the microalgae, or the harvesting may be performed by gravity extraction, taking advantage of gravity such that the harvested algae fall towards a reservoir; to this end, regardless of the case, it comprises a chute with a sufficient slope, which is integrated at the bottom of the culture container ( 1 ).
[0087] The chute fulfils a two-fold function: it accumulates dirt and allows for easy harvesting, either by gravity, by placing a tank at a lower height than the chute, or by forced circulation through the pump.
[0088] In order to help to carry the dirt to the chute, one or several cleaning brushes are coupled to the elements that generate the light-darkness cycles; these brushes slightly touch the bottom of the container ( 1 ) in order to gradually carry what is accumulated in the bottom of the container ( 1 ) towards the chute. Thus, the dirt will accumulate in the chute, since, when the brush passes through the chute, it will let the dirt fall, thanks to gravity, to the bottom thereof. In this way, the chute is capable of accumulating the solid sediments and makes it possible to remove a large part of the sediments that are not microalgae.
[0089] Preferably, the chute is arranged from the centre of the container ( 1 ) to the perimeter of the container ( 1 ), where there is an opening that may act as a harvesting point.
[0090] Regardless of the presence of the chute, the cleaning brushes coupled to the means that rotate around a plane parallel to the base of the container ( 1 ) touch the base of the container ( 1 ), the wall of the container ( 1 ), or both. Moreover, the shape of the part of these brushes that touches the wall makes it possible for them to displace the dirt towards the upper part of the perimeter of the container ( 1 ), and is even able to expel the dirt outside the container ( 1 ). Alternatively, thanks to the shape thereof, the part of the brushes that touches the wall directs the dirt towards the lower part of the perimeter of the container ( 1 ), thereby bringing together the dirt from the wall and the dirt from the base, for the subsequent cleaning thereof, either through the dirt falling into the chute or by means of periodic maintenance. The brushes are placed on the sweep blades described above.
[0091] In both cases, the continuous cleaning, i.e. the fact that the brushes always rotate with the rotation of the vertical rotating support, allows for exhaustive cleaning of the container ( 1 ). However, the friction generated by the brushes when they move through the bottom or the walls may increase the energy consumption in the rotation; for this reason, the cleaning brushes may be associated with a brush engagement system that allows for the brushes to operate only during certain given time intervals.
[0092] 5. A culture medium injection device, which feeds the culture system container ( 1 ).
[0093] All the systems comprised in the culture system are controlled by a central control system that evaluates all the system variables and sends the appropriate instructions to each of the actuators.
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The present invention relates to a microalgae culture system under external conditions that comprises a shallow-depth culture container, a rotation system for the generation of light-darkness cycles and re-suspension, which maximises the photosynthetic efficiency of the microalgae and homogenises the nutrients supplied such that the microalgae may adequately grow in all the areas of the photobioreactor, a gas exchange and temperature control system, which makes it possible to control and maintain the culture parameters under the optimal microalgae growth conditions, a filtration and self-cleaning system, an energy control and saving system, which makes it possible to maintain the desired conditions with the lowest energy expenditure, and a cover system, which filters ultraviolet and/or infrared radiation and makes it possible to control contaminations, the temperature and the evaporation.
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RELATED APPLICATIONS
The present application is a continuation of U.S. patent application Ser. No. 13/157,483, filed Jun. 10, 2011, which is a continuation of U.S. patent application Ser. No. 12/109,841, filed Apr. 25, 2008, now U.S. Pat. No. 7,980,129, which claims the benefit of U.S. provisional application Ser. No. 60/913,961, filed Apr. 25, 2007, the disclosures of which are hereby incorporated by reference.
TECHNICAL BACKGROUND
The disclosure relates generally to monitors for measuring the weight of an object, such as a feed bin, and methods of installing such monitors. More particularly, the disclosure relates to monitors having a suspended load cell that is positioned above a bottom of a leg of the object.
BACKGROUND
Many animal finishing facilities have bulk bins and automated feed delivery systems. In theory, these bins and delivery systems are intended to assure an uninterrupted flow of feed to the feeder. In reality, however, various known delivery systems result in varying disruptions of feed availability, which may have very serious consequences. For example, out-of-feed events can cause animal health problems, such as ulcers, particularly in pigs. Other potential health problems include, for example, cannibalistic tail biting and Hemorrhagic Bowel Syndrome, which is often fatal to the animal. Moreover, it is believed that even one out-of-feed event can have a prolonged negative effect on weight gain. Paid dividends can be directly affected as a result.
Out-of-feed events can be caused by a variety of causes. One notable cause is human error. Human errors are generally associated with empty bins, which occur when feed is not ordered, prepared, and delivered in a timely manner. Other causes of out-of-feed events include, for example, bridging and rat-holing of the feed. In these cases, the feed still remains in the bin, but does not flow to the delivery or auger system. As a result, even though feed is present in the bin, it is not delivered to the animals. When this occurs, the feed delivery system may shut down due to its extended run timers. No feed is then delivered until the feed delivery system is manually reset. If producers are not closely monitoring the feed delivery system, animals can be without feed for extended periods of time. While out-of-feed events can be prevented, in practice, they occur quite often.
One method of preventing out-of-feed events involves personally checking each bin by climbing up a ladder to the top of the bin and visually noting and monitoring the level of the bin. This method is labor-intensive and can be quite dangerous, especially in frigid, icy, or wet weather. To save time and avoid safety risks associated with climbing to the top of the bin, some workers have resorted to physically hitting the bin to estimate the level of the feed by listening to the sound reverberation. This method, however, does not provide the producer with very accurate information. It is also still labor-intensive because the worker has to personally check each individual bin. Further, as compared to the past, it is now more common for farms to be isolated from the workers. As a result, it takes more effort to check and monitor the feed systems. Therefore, the feed bins often are not checked frequently enough to prevent out-of-feed events because it takes too much time to check the bins, and, additionally, rush orders are often not fulfilled quickly enough.
Accordingly, electronic monitors have been devised to monitor feed levels. These known electronic monitors are equipped with compression load cells positioned on a concrete slab underneath the bin legs. The load cells measure the amount of the feed in the bin and are able to track the level and the changes in the feed weight, for example, from deliveries and consumption. Some of these known electronic monitors can make feed level data available to producers by telephone. Many producers choose not to implement these known systems, however, because they are costly and are difficult to retrofit to existing bins. Separate jacks or cranes are required so that the bin legs can be raised approximately 3-4 inches off of the concrete slab. Raising the bin disrupts the connections between the bins and the conveyor pipes that carry the feed from the bin to the feeding point. Known electronic feed bin monitors can also be unreliable because they are often susceptible to adverse affects on the accuracy of their measurements due to ice and foreign material under the supporting mechanisms. These supporting mechanisms include foot pads that are bolted to the concrete slab beneath the bin. Bolting the foot pads to the concrete slab introduces torques that can twist the load cell system enough to produce false readings at times.
Some other known systems are sonar or ultrasound based. One drawback of such systems is that they only report a feed level, not weight. As a result, these systems have difficulty maintaining accuracy when, for example, there is bridging or rat-holing of feed, there are significant changes in feed density, or there are temperature variations. All of these events can alter the correlation between feed level and the true amount or weight of feed. Known sonar or ultrasound based systems can also only provide level monitoring. Thus, they cannot accurately measure feed delivered or consumed by weight. The present invention addresses problems associated with the related art.
SUMMARY OF THE DISCLOSURE
According to various example embodiments, a bin monitoring system functions both as a device for lifting the bin and as a weighing system for monitoring or measuring the level of feed in a feed bin. Various embodiments having a suspended load cell and methods of retrofitting the bin monitoring system to existing bins are provided. Further, the accuracy provided by various embodiments enable one to accurately predict when the feed bin will be empty. Thus, the feed mill can be aware of anticipated needs days in advance, allowing the feed mill to better optimize its scheduling and deliveries.
One embodiment is directed to a feed bin monitoring system that has a suspended load cell that accurately measures the amount of feed going into and out of a feed bin having bin legs that support the bin above a foundation. The feed bin monitoring system of this embodiment can quickly detect if no feed is being consumed by the animals due to, for example, bridging of the feed in the bin. The feed bin monitoring system includes a frame configured to be securable to the foundation. A load cell is joined to the frame and is configured to measure a weight of the bin. A lifting mechanism is arranged to selectively lift the bin leg, thus applying the load to the load cell. Another aspect of the invention is directed to a method of monitoring an amount of feed in a feed bin having a plurality of bin legs by operatively connecting at least one feed bin monitor to each of the bin legs and transmitting data collected from the load cell to a display device.
Another aspect of this invention is directed to a method of installing a bin monitoring system, such as described above, to a leg of a feed bin. The method generally includes the steps of securing the bin monitoring system to at least one of the bin legs and using a bolt to raise the bin legs preferably no more than approximately 0.5 inches above the ground, thus facilitating retrofitting of existing bins.
Various embodiments may provide certain advantages. For instance, feed levels can be monitored easily and accurately so that out-of-feed events can be significantly reduced. Also, feeding animals with feed bins equipped with automatic bin monitoring systems reduces the need for expedited orders and allows feed producers to predict production needs in advance. Feed throughput may be improved, and feed transportation costs may be reduced. Further, the bin monitoring systems described herein can be retrofitted to existing bins easily and inexpensively, thereby reducing implementation costs.
Additional objects, advantages, and features will become apparent from the following description and the claims that follow, considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a front plan view of an embodiment of a bin monitoring system.
FIG. 1B is a front view of the bin monitoring system similar to that of FIG. 1A , wherein the bin monitoring system is operatively attached to a bin leg.
FIG. 1C is an enlarged, partial, perspective view of the bin monitoring system illustrated in FIG. 1B .
FIG. 1D is a rear view of the bin monitoring system of FIGS. 1B-1C operatively connected to the bin leg.
FIG. 2A is a side view of the bin monitoring system of FIG. 1A .
FIG. 2B is another side view of the bin monitoring system similar to that of FIGS. 1B-1D , wherein the bin monitoring system is operatively attached to the bin leg.
FIG. 3A is a front view of a frame of the bin monitoring system of FIG. 1A illustrating optional folding of the frame.
FIG. 3B is a plan view of the completed frame of FIG. 3A .
FIG. 3C is a side view of the frame of FIG. 3B .
FIG. 4A is a plan view of a channel bracket of the bin monitoring system of FIG. 1A .
FIG. 4B is front view of the folded channel bracket of FIG. 4A .
FIG. 4C is a side view of the completed channel bracket of FIG. 4B .
FIG. 5A is a top view of a load block of the bin monitoring system of FIG. 1A .
FIG. 5B is a cross-sectional, side view of the load block of FIG. 5A .
FIG. 6 is a view of a bin monitoring system attached to each leg of two adjacent bins according to another embodiment.
FIG. 7 illustrates another embodiment in which the channel bracket of FIG. 1A is replaced with an alternate mechanical connector including a chain link suspension.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of various embodiments implemented in the context of monitoring the volume or weight of feed bins and installing such monitoring systems is to be construed by way of illustration rather than limitation. This description is not intended to limit the invention or its applications or uses. For example, while various embodiments are described as being implemented in this context, it will be appreciated that the principles of the disclosure are applicable to other environments, as will be apparent to one of ordinary skill in the art.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments. It will be apparent to one skilled in the art that some embodiments may be practiced without some or all of these specific details. In other instances, well known components and process steps have not been described in detail.
Embodiments of the bin monitoring system are illustrated in FIGS. 1A-6 . Referring now in particular to FIGS. 1A-3C and 6 , a bin monitoring system 10 includes a frame 12 . In some embodiments, the frame 12 is A-shaped and has a top 14 and two legs or supports 20 a and 20 b extending diagonally downward from the top 14 . In the illustrated embodiments, each support 20 a and 20 b has a respective flange 24 a and 24 b with at least one respective flange aperture 28 a and 28 b for anchoring the frame 12 to a foundation such as a concrete slab C, as most bins are installed on concrete slabs. The top 14 includes a bolt aperture 16 that receives a bolt 18 for securing the frame 12 to the top of a load cell 50 . In some embodiments, the frame 12 can be constructed of fabricated iron. Alternatively, the frame can be constructed of fabricated channel iron.
In some embodiments, the load cell 50 is implemented as an S-type load cell for measuring the tension or changing weight of a bin B. The bin monitoring system 10 incorporates the load cell 50 to measure the weight and changes of weight of the bin B. An example implementation of the load cell 50 is disclosed in U.S. patent application Ser. No. 11/422,910 of Jaeger et al., the teachings of which are herein incorporated by reference in their entirety. In some embodiments, the load cell 50 includes an electrical connection 52 having a wire that passes through an aperture 22 in one of the supports 20 a and 20 b to a transmitter (not shown) such that data collected from the load cell 50 can be accessed via a remote location such as, for example, by a wired, wireless, or mobile telephone or using a network such as the Internet.
It is further contemplated that the bin monitoring system 10 may be an element of a larger system in which the data transmitted may be compiled with other data, such as animal weights, so that multiple variables can be monitored and tracked in one central location. Such a larger system can also include, for example, a component for generating reports, such as a bin status report, a configuration report, an alarm settings report, a feed usage report, and a bin summary report. The bin status report may illustrate an image of a feed bin showing the current weight, alarm settings, and alarm conditions. The configuration report may list the configuration for the setup menu, interface menu, and computer port. The alarm settings report may list the alarm settings for each indicator. The feed usage report may list daily feed usage sorted by date and the total feed delivered for a selected date range. The bin summary report may list the current bin weights and any alarm conditions for the feed bins.
Now also referring to FIGS. 4A-C , the bin monitoring system 10 additionally includes a mechanical connector, in this case a channel bracket 60 , that is used to connect the bin monitoring system 10 to a leg L of the bin B. The channel bracket 60 may be generally U-shaped, being deeper at the top than at the bottom, to correspond to the shape of the bin leg L. In some embodiments, the bin monitoring system 10 includes a limiting mechanism 66 to restrict the upward movement of the channel bracket 60 . The limiting mechanism 66 prevents the bin B from lifting and blowing over when, for example, there is a gust of wind and the bin B is empty. As shown, the limiting mechanism 66 may be a stop strap having bolt apertures 68 for use with a bolt 69 to secure the strap to the frame 12 as shown in FIGS. 1A-1C . The channel bracket 60 further includes a slot 62 for receiving and in some instances, supporting a load block 70 and is deep enough such that when the channel bracket 60 is bolted to the bin leg L and the frame 12 is secured to the concrete slab C, the channel bracket 60 extends beyond the stop strap 66 , allowing it to contact and be restricted by the stop strap 66 when the bin B is lifted too high. This configuration is also illustrated in FIG. 2A . In alternative embodiments, the channel bracket 60 may be replaced with a chain link suspension or mechanical connector 80 attached to a clevis 82 , as shown in FIG. 7 , or another similar system.
Now further referring to FIGS. 5A-5B , as previously mentioned, the bin monitoring system 10 further includes the load block 70 , which is received within the slot 62 of the channel bracket 60 and is supported by the channel bracket 60 until the bracket 60 is elevated. The load block 70 is illustrated in FIGS. 5A-5B as having a bolt aperture 72 . The load block 70 is placed in the slot 62 of the channel bracket 60 . A threaded bolt 65 is then placed through a bolt aperture 72 of the load block 70 and threaded into the load cell 50 . The load block 70 can move within the slot 62 . This configuration allows for some misalignment of the channel bracket 60 .
A typical feed bin has 4 , 6 , or 8 generally U-shaped legs. The bin monitoring system 10 may be placed alongside each leg L and bolted to the concrete slab C with an anchor bolt 30 through two of the flange apertures 28 a and 28 b . Two more bolts 65 may be pressed through the bolt holes 64 of the channel bracket 60 to connect the bin monitoring system 10 to the bin leg L.
As described above, the bin monitoring system 10 includes the threaded bolt 18 , which secures the load cell 50 to the frame 12 . According to various embodiments, the bolt 18 also serves as a jack to lift and support the load cell 50 when the load cell 50 is suspended off of the concrete slab C. In some embodiments, the bin monitoring system 10 jacks up the bin B no higher than about 0.75 inches, preferably no higher than about 0.5 inches above the concrete slab C. Because installing the bin monitoring system 10 does not require the bin B to be significantly lifted, existing bins may be retrofitted without having to empty the bin or disconnect flex augers and associated piping.
To install the bin monitoring system 10 according to one example method, the load cell 50 , frame 12 , and limiting mechanism 66 are operatively assembled. The footpads are then disconnected from the bin legs L. Next, two 0.5 inch holes are drilled into the bin legs L for the channel bracket 60 . In the next step, the channel bracket 60 is first mounted adjacent the side of the leg L such that any space in between the channel bracket 60 and the leg L is reduced. Once the channel bracket 60 is attached adjacent the leg L, the frame 12 is aligned to the bin leg L and is secured with concrete anchor bolts 30 . The channel bracket 60 is connected to a threaded load cell 50 by a threaded bolt 40 that can also function as a jack to lift the bin leg L. As the bolt 40 is rotated, e.g., seven times, the load cell 50 is moved upwards and correspondingly moves the bin leg L upwards. In the next step, a summing box or the transmitter (not shown) is mounted to the bin B and is operatively connected to the load cell(s) 50 . Next, the summing box can be wired to the bin monitoring system 10 . Next, wiring to the load cell 50 is secured to the bin support frame, e.g., using one or more cable ties. The bin monitoring system 10 is then connected to the on-site network to enable communication with a remote monitoring system. Next, preferably three of the bin legs L are electrically grounded above each frame using the anchor bolts.
As described above, the bin monitoring system 10 can be used to determine how much feed enters and exits a feed bin. In this way, the bin monitoring system 10 facilitates the determination of when more feed should be ordered. In addition, the bin monitoring system 10 facilitates verifying how much feed is actually delivered when the bins are refilled and how much is being consumed. As a result, potential out-of-feed events can be monitored, animal performance based on feed consumption can be correlated, and future bin levels can be predicted accurately.
As demonstrated by the foregoing discussion, various embodiments may provide certain benefits. For instance, the bin monitoring system 10 can greatly reduce monitoring costs. The required labor can be reduced because multiple bin feed levels can be quickly, simultaneously, and accurately monitored at a central location, as compared with the conventional approach of visually inspecting each bin individually. Safety hazards can also be reduced because workers do not need to climb feed bins to inspect them.
Additionally, logistical savings can be realized by the bin monitoring system 10 . Typically, feed mills have large demands on Mondays and Fridays. On these days, the mills run over capacity and often need to pay overtime to drivers and milling employees to fill tanks for the weekend or to catch up and fill empty tanks on Mondays. On Tuesdays, Wednesdays, and Thursdays, the mills run under capacity. Use of the bin monitoring system 10 allow the feed mill to level its production flow out over the week by delivering feed early to some bins and just-in-time to others. Accurate monitoring of feed bins allows producers to better predict and schedule when they will need to replenish the feed bins, which in turn will reduce the amount of expedited orders and allow the feed mill to plan their production. By allowing the feed mill to better plan its production, the feed mill can schedule the bottlenecks to the maximum increasing throughput. Overtime is saved in both the feed mill and the trucking, and the incidence of empty compartments or “air tons” can be reduced. Rush orders can be eliminated by better planning, thus greatly reducing the frequency of expedited orders and the associated expense.
It will be understood by those who practice the embodiments described herein and those skilled in the art that various modifications and improvements may be made without departing from the spirit and scope of the disclosed embodiments. The scope of protection afforded is to be determined solely by the claims and by the breadth of interpretation allowed by law.
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A monitoring system functions both as a device for lifting the object and as a weighing system for monitoring or measuring the weight of an object, such as a feed bin. Various embodiments having a suspended load cell and methods of retrofitting the monitoring system to existing object are provided. Further, the accuracy provided by various embodiments enables one to accurately predict when the feed bin will be empty. Thus, the feed mill can be aware of anticipated needs days in advance, allowing the feed mill to better optimize its scheduling and deliveries.
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BACKGROUND OF THE INVENTION
1. Technical Field
The present invention generally relates to vehicle drivelines and more particularly to a differential assembly for a vehicle driveline that selectively transmits power to a set of vehicle wheels.
2. Discussion
Modernly, vehicle manufacturers are employing vehicle drivetrains having more than one drive axle to improve vehicle traction. Common arrangements include part-time four-wheel drive systems that employ a front axle disconnect to selectively disconnect the front wheels from the front of the vehicle drivetrain. These arrangements are commonly known as rear drive/front assist drivetrains. Disconnection of the front wheels from the front of the vehicle drivetrain prevents the front drive wheels from rotating the front of the vehicle drive train at road speed, thereby saving wear and tear on the vehicle driveline. The front axle disconnect also controls the coupling of the front wheels to the front of the vehicle driveline such that the front driveshaft will spin at the same speed as the rear driveshaft.
Despite the relatively widespread use of such drivetrain arrangements, several drawbacks are known to exist, such as their cost and the amount of time that is sometimes necessary for the front axle disconnect to engage and disengage the front of the vehicle driveline to the front wheels. In isolating the front wheels from the rest of the front driveline, front axle disconnects typically use a sliding sleeve to connect or disconnect an axle shaft from the front differential side gear. Vehicle manufacturers typically use either vacuum or heat to move the engagement sleeve and as such, the time that is required to shift the sliding sleeve to a desired position can be relatively long, particularly when heat is employed to heat a fluid to generate sufficient pressure to cause the engagement sleeve to move.
Accordingly, there remains a need in the art for a vehicle driveline that is less costly and which provides improved response in the time for the engagement and disengagement of the vehicle drivetrain to the vehicle wheels.
SUMMARY OF THE INVENTION
In one preferred form, the present invention provides a differential assembly having first, second and third structures, a differential gear set and a biasing mechanism. The first structure is configured to rotate along a differential axis in response to receipt of a rotational input. The second structure is supported for rotation on the differential axis. The third structure is supported for rotation on the differential axis and disposed between the first and second structures. The third structure can be operated in an engaged condition for transmitting torque from the first structure to the second structure and a disengaged condition for inhibiting the transmission of torque from the first structure to the second structure. The differential gear set is coupled to and rotatably supported within the second structure. The biasing mechanism biases the third structure in the disengaged condition. The third structure is placed in the engaged condition if a torsional magnitude of the rotational input exceeds by a predetermined amount a torsional magnitude of a rotational force exerted through the differential gear set.
In another preferred form, the present invention provides a vehicle drive train having a transfer case assembly and first and second axle assemblies. The transfer case assembly receives a rotational input from a vehicle power source and produces first and second intermediate rotational outputs therefrom. The first axle assembly is coupled to the transfer case assembly, receives the first intermediate rotational output therefrom and produces a first drive wheel output for rotating a first set of drive wheels. The second axle assembly has a differential assembly with a differential housing member configured to rotate about differential axis in response to receipt of the second intermediate rotational output, a differential case member supported for rotation on the differential axis, a cam member supported for rotation on the differential axis and disposed between the differential housing member and the differential case member and a differential gear set. The cam member can be operated in an engaged condition for transmitting torque from the differential housing member to the differential case member and a disengaged condition for inhibiting the transmission of torque from the differential housing member to the differential case member. The differential gear set is coupled to and rotatably supported within the differential case member. Operation of the cam member in the engaged condition permits the differential gear set to produce a second drive wheel output to rotate a second set of drive wheels. Operation of the cam member in the disengaged condition inhibits the differential from producing the second drive wheel output and permitting the second set of drive wheels to rotate freely.
BRIEF DESCRIPTION OF THE DRAWINGS
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a schematic view of the drivetrain of an exemplary motor vehicle constructed in accordance with the teachings of the present invention;
FIG. 2 is an exploded perspective view of a portion of the drivetrain of FIG. 1 illustrating the rear axle assembly in greater detail;
FIG. 3 is an exploded perspective view of a portion of the drivetrain of FIG. 1 illustrating the front axle assembly in greater detail; and
FIG. 4 is an exploded perspective view of a portion of the front axle assembly of FIG. 3 illustrating the differential assembly in greater detail.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1 of the drawings, a drivetrain 10 for a part-time four-wheel drive vehicle 12 is schematically shown interactively associated with a differential assembly 14 constructed in accordance with the teachings of the present invention. The drivetrain 10 includes a rear driveline 20 and a front driveline 22 which are both drivable from a source of power, such as an engine 24 , through a transmission 26 which may be of either the manual or automatic type. In the particular embodiment shown, the drivetrain 10 is a rear drive/front assist system which incorporates a transfer case 28 for transmitting drive torque from the engine 24 and the transmission 26 to the rear and front drivelines 20 and 22 . The transfer case 28 is preferably a non-differentiating transfer case that causes the rear and front transfer case output shafts 30 and 32 , respectively to rotate at the same rotational speed.
With additional reference to FIG. 2, the rear driveline 20 is conventional in its construction and operation and includes a pair of rear wheels 36 connected at the opposite ends of a rear axle assembly 38 having a rear differential assembly 40 coupled to one end of a rear prop shaft 42 , the opposite end of which is interconnected to a rear transfer case output shaft 30 of the transfer case 28 . The rear axle assembly 38 includes a rear axle housing 44 , a rear pinion shaft 46 and a pair of rear axle shafts 48 that are interconnected to a respective one of the left and right rear wheels 36 . The rear axle housing 44 has a wall member 50 that defines a differential cavity 52 into which the rear differential assembly 40 is rotatably supported. The rear pinion shaft 46 has a pinion gear 54 that is fixed thereto which drives a ring gear 56 that is fixed to a differential case 58 of the rear differential assembly 40 . A gearset 60 supported within the differential case 58 transfers rotary power from the differential case 58 to the rear axle shafts 48 to facilitate relative rotation (i.e., differentiation) therebetween. Thus, rotary power from the engine 24 is transmitted to the rear axle shafts 48 for driving the left and right rear wheels 36 via the transmission 26 , the transfer case 28 , the rear prop shaft 42 , the rear pinion shaft 46 , the differential case 58 and the gearset 60 .
With reference to FIGS. 1 and 3, the front driveline 22 includes a pair of front wheels 66 connected at the opposite ends of a front axle assembly 68 having the differential assembly 14 coupled to one end of a front prop shaft 72 , the opposite end of which is interconnected to the front transfer case output shaft 32 of the transfer case 28 . The front axle assembly 68 includes a front axle housing 74 , a front pinion shaft 76 , the front differential assembly 14 , a pair of front axle shafts 78 that are interconnected to left and right front wheels 66 . The front axle housing 74 has a wall member 80 that defines a differential cavity 82 into which the front differential assembly 14 is supported for rotation about a differential axis 83 . The front pinion shaft 76 has a pinion gear 84 that is fixed thereto which drives a ring gear 86 that is fixed to a differential housing assembly 88 of the front differential assembly 14 .
With reference to FIG. 4, the front differential assembly 14 is shown in greater detail to also include a cam member 90 , a differential case member 92 , a biasing mechanism 94 , a gearset 96 and a thrust washer 98 . The differential housing assembly 88 includes a first housing member 100 and a second housing member 102 that collectively define a differential cavity 104 . The first housing member 100 is generally hollow and includes a retaining flange 106 , an extending portion 108 and a first housing aperture 110 . The retaining flange 106 is operable for receiving a plurality of fasteners 114 to permit the first and second housing members 100 and 102 and the ring gear 86 to be fixedly but removably coupled together. The extending portion 108 is configured to at least partially extend into a second housing aperture 118 formed into the second housing member 102 . The extending portion 108 terminates at an abutting face 120 that is configured to abut an abutting face 122 formed in the cam member 90 . Each of the abutting faces 120 and 122 are illustrated to be formed by a plurality of peaks 124 and valleys 126 , the purpose of which will be discussed in greater detail, below.
The cam member 90 is illustrated to have a generally hollow cylindrical configuration and is rotatably supported within the differential cavity 104 between the first housing member 100 and the differential case member 92 . The cam member 90 includes a cam portion 130 into which the abutting face 122 is formed, a collar portion 132 , a plurality of teeth 134 and an aperture 136 extending through the cam member 90 and formed along the longitudinal axis of the cam member 90 . Bushings or bearings (not specifically shown) may be mounted within the second housing member 102 in the second housing aperture 118 to support the cam member 90 for rotation within the differential cavity 104 about the differential axis 83 . Each of the plurality of teeth 134 formed into the cam member 90 are illustrated to have a generally square configuration that is configured to meshingly engage a plurality of teeth 140 formed in the differential case member 92 to permit rotary power to be transferred between the cam member 90 and the differential case member 92 . Those skilled in the art will understand, however, that the particular configuration of the teeth 134 and 140 which is illustrated is merely exemplary and not intended to be limiting in any manner. Accordingly, those skilled in the art will understand that the teeth 134 and 140 may have another configuration or that they may be omitted altogether if another means for transferring power between the cam member 90 and the differential case member 92 , such as one that utilizes friction between the mating surfaces of the cam member 90 and the differential case member 92 , is employed.
The cam member 90 is operable in a disengaged condition and an engaged condition. When positioned in the disengaged condition, the peaks 124 and valleys 126 of the abutting face 120 of the first housing member 100 are positioned against the valleys 126 and peaks 124 , respectively, of the abutting face 122 of the cam member 90 and the teeth 134 formed in the cam member 90 are spaced apart from the teeth 140 formed into the differential case member 92 . As such, rotary power cannot be transmitted between the cam member 90 and the differential case member 92 . When positioned in the engaged condition, the peaks 124 and valleys 126 of the abutting face 120 of the first housing member 100 are positioned against the peaks 124 and valleys 126 , respectively, of the abutting face 122 of the cam member 90 and the teeth 134 formed in the cam member 90 are meshingly engaged with the teeth 140 formed into the differential case member 92 , thereby facilitating the transmission of rotary power therebetween.
The differential case member 92 is also illustrated to have a generally hollow cylindrical configuration. In addition to the teeth 140 that are formed into an extending portion 144 , the differential case member 92 includes a flange member 146 and a pinion shaft aperture 148 which is positioned generally perpendicularly to the longitudinal axis of the differential case member 92 . As with the cam member 90 , bushings or bearings (not specifically shown) may be mounted within the second housing member 102 in the second housing aperture 118 to support the differential case member 92 for rotation within the differential cavity 104 about the differential axis 83 . The end of the differential case member 92 opposite the end having the teeth 140 terminates at a thrust flange 150 that is configured to contact the thrust washer 98 . The thrust washer 98 is disposed between the thrust flange 150 and an end portion 154 of the second housing member 102 being configured to reduce the friction between the thrust flange 150 and the end portion 154 .
The gearset 96 is illustrated to include a pinion shaft 170 , a pair of pinions 172 and a pair of side gears 174 . The pinion shaft 170 extends through the pinion shaft aperture 148 and is fixedly coupled to the differential case member 92 . The pinion shaft 170 rotatably supports the pair of pinions 172 , each of which is meshingly engaged to the pair of side gears 174 . The front axle shafts 78 are coupled at a first end to an associated one of the side gears 174 and at an opposite end to an associated one of the left and right front wheels 66 .
The biasing mechanism 94 is operable for maintaining the cam member 90 in the disengaged condition until a predetermined condition has occurred. In the particular embodiment illustrated, the biasing mechanism 94 is a compression spring 180 that encircles the teeth 134 and 140 of the cam member 90 and the differential case member 92 . The spring 180 is operable for generating a biasing force that is transmitted to the collar portion 132 and the flange member 146 to thereby axially space the cam member 90 and the differential case member 92 apart along the differential axis 83 .
Rotary power from the engine 24 is transmitted to the differential assembly 14 via the transmission 26 , the transfer case 28 , the front prop shaft 72 and the pinion shaft 76 , causing the differential housing assembly 88 to rotate about the differential axis 83 . When the cam member 90 is in the disengaged condition, rotary power is not transmitted through the cam member 90 to the differential case member 92 , and as such, the rotary power is not transmitted to the front wheels 66 via the front axle shafts 78 . The front wheels 66 , however, are free to rotate at the road speed of the vehicle and as such, cause the front axle shafts 78 , the gearset 96 and the differential case member 92 to rotate about the differential axis 83 . When the cam member 90 is in the engaged condition, rotary power is transmitted through the cam member 90 to the differential case member 92 , and as such, the rotary power is transmitted to the front wheels 66 via the differential case member 92 , the gearset 96 and the front axle shafts 78 . In the particular example provided, the configuration of the gear set 96 provides the differential assembly 14 with a bias ratio of one (1) when the cam member 90 is in the engaged condition.
In operation, drive torque produced by the engine 24 is transmitted via the transmission 26 and the transfer case 28 to the rear and front transfer case output shafts 30 and 32 . In normal operating conditions where the rear and front wheels 36 and 66 have good traction, the engine drive torque is substantially transmitted through the rear prop shaft 42 to the rear axle assembly 38 for driving the left and right rear wheels 36 . This distribution of the engine drive torque results from the biasing of the cam member 90 in the disengaged condition. As traction in the rear wheels 36 is sufficiently good, the driveline 10 is not able to transmit enough of the drive torque to the front prop shaft 72 to cause the first housing member 100 to rotate relative to the cam member 90 , and as such, the cam member 90 will remain in the disengaged condition and the front wheels 66 are permitted to spin freely.
When the rear wheels 36 begin to slip in excess of a predetermined amount, however, the drive torque transmitted through the front prop shaft 72 will exceed the magnitude of the torque that is exerted through the gearset 96 by the rotation of the front wheels 66 , permitting the first housing member 100 to overcome the biasing force generated by the biasing mechanism 94 and rotate relative to the cam member 90 causing the cam member 90 to be positioned in the engaged condition. As such, engine drive torque is distributed to the front wheels 66 through the gearset 96 .
Construction of the drivetrain 10 in this manner is highly advantageous in that the differential assembly 14 produces a relatively simple and inexpensive part-time four-wheel drive system that may be instantaneously actuated in response to wheel slip without the use of sensors or electronic control mechanisms.
While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the description of the appended claims.
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A differential assembly having a first structure, which is configured to rotate along a differential axis in response to receipt of a rotational input, a second structure, which is supported for rotation on the differential axis, a third structure, which is supported for rotation on the differential axis and disposed between the first and second structures and operable in an engaged condition that transmits torque between the first and second structures and a disengaged condition that inhibits torque transmission between the first and second structures, a differential gear set, which is coupled to and rotatably supported within the second structure, and a biasing mechanism, which biases the third structure in the disengaged condition. The third structure is placed in the engaged condition if a torsional magnitude of the rotational input exceeds a rotational force that is exerted through the differential gear set. A vehicle drive train is also provided.
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CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/661,158, filed Jun. 18, 2012, which is hereby incorporated by reference in its entirety.
STATEMENT OF GOVERNMENT INTEREST
[0002] The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefor.
FIELD OF THE INVENTION
[0003] The invention relates in general to treating water in the ballast tank of a ship or barge.
BACKGROUND
[0004] Ships that transport goods around the world can carry nonindigenous (exotic) species in ballast water. The release of the ballast water from the ships is a major transport mechanism for the nonindigenous aquatic organisms (Carlton, 1985) as recognized by the U.S. National Invasive Species Control Act of 1996 (P.L. 104-332). Approximately 70,000 major cargo ships operating worldwide (Bureau of Transportation Statistics, 2008) pump ballast water on board to ensure stability and balance. Large vessels can carry in excess of 200,000 m 3 of ballast, which is released in varying amounts at or when approaching cargo loading ports. In 1991, U.S. waters alone received approximately 57,000,000 metric tons of ballast water from foreign ports (Carlton et al., 1994). Ship surveys have demonstrated that ballast water is in general a non-selective transfer mechanism—many taxa representing planktonic and nectonic organisms capable of passing through coarse ballast water intake screens are common. These include bacteria, larval fish, zooplankton, and bloom forming dinoflagellates (Chu et al., 1997; Carlton and Geller, 1993).
[0005] The introduction of the nonindigenous (exotic) species has had dramatic negative effects on marine, estuarine, and freshwater ecosystems in the United States and abroad (Elton, 1958; Mooney and Drake, 1986; Chesapeake Bay Commission, 1995; NAS, 1996). Effects include alteration of the structure and dynamics of the ecosystem involved, including extirpation of native species (Office of Technology Assessment Archive, 1993).
[0006] The current state of the art for treating ballast water involves treating the water as it is pumped into or out of the ballast tanks. Methods for treating the water as it is pumped out the tanks are tremendously expensive and time consuming, and it is considered cost prohibitive to treat all water that is pumped into all tanks. The alternative to treating the water as it is pumped into or out of the tanks is to treat it while it resides in the tanks as the ship travels from port to port. To accomplish this, the entire volume of the tanks must be completely mixed in a relatively short time to ensure all the water in the tanks is exposed to the treatment method. This is especially true in emergency situations when a ship is grounded and the water in the ballast tanks must be treated before it is pumped out as part of the response plan to free the grounded vessel.
[0007] Methods for mixing water in tanks as part of a treatment process have been developed to treat waste water from municipal sewage systems, manufacturing, and industry. These treatment methods generally incorporate large circular or square tanks to hold the water during treatment, mixing, and neutralization (if required) before the water is released. These tanks generally lack geometric complexity and are therefore relatively easy to mix using a variety of mechanical methods (i.e. axial mixers, eductors, air, and nozzles). The ballast tanks on ships are quite different. The tanks are engineered to be part of the structure of the ship and are integral to the stability and integrity of the ship. As a result, most ships have multiple ballast tanks (ranging in number from a few to dozens) that are geometrically complex and often have baffles, support structures, web frames, stringers, stations, piping, and rose boxes inside the tanks. Also, there can be different types of ballast tanks with different geometries on a single ship. This complexity makes it difficult to mix the water in the tanks as part of a treatment method. Moreover, there are about 70,000 cargo ships operating worldwide. It would cost the shipping industry billions of dollars to install and maintain permanent mixing systems in all ballast tanks on all ships.
SUMMARY
[0008] A system, method, and apparatus for treating ship ballast water is presented herein. The system includes a ballast tank that stores ballast water and one or more nozzles located in the ballast tank. A pump supplies water to the nozzles and a biocide is injected into the water supplied to the nozzles or directly into the tank at alternative locations. The nozzles are strategically located in the ballast tank to circulate the ballast water and mix the chemical with the ballast water without removing the ballast water from the ballast tank. The nozzles may be operated alternately and intermittently to reduce equipment weight and power requirements and to optimize mixing rates.
[0009] The nozzle mixing system can be implemented on an “as needed” basis, is relatively inexpensive to purchase and maintain, is simple to implement, is effective at quickly (a few hours) mixing the contents of the tank, and reduces exotic species introductions and provides improved control of those species introduced in the past.
[0010] The nozzle mixing system and method enhances the mixing of ballast water tanks. Enhanced mixing is needed to 1) ensure all water in the tank is adequately mixed with a biocide for the required exposure time, 2) ensure the biocide is adequately mixed with a neutralizing agent (if required) before the water is released into the environment, 3) improve saltwater exchange efficiency as a means of preventing the spread of exotic species from port to port, and 4) facilitate the suspension of accumulated sediments in the tanks to enhance the efficacy of biocide treatment of exotic species that may be present in the sediment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Various aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings. The drawings are not necessarily drawn to scale. In the drawings:
[0012] FIG. 1 is a schematic perspective view of a ship ballast tank with a nozzle mixing system according to an embodiment of the invention;
[0013] FIG. 2A is a schematic cross-sectional view of a cargo ship illustrating mixing of water in two ballast tanks with double-bottom areas according to an embodiment of the invention;
[0014] FIG. 2B is a schematic top view of one of the ballast tanks shown in FIG. 2A illustrating placement of nozzles according to an embodiment of the invention;
[0015] FIG. 2C is a schematic perspective view of the ballast tank of FIG. 2B according to an embodiment of the invention;
[0016] FIG. 3A is a schematic, cross-sectional view of a cargo ship with two L-shaped ballast tanks according to an embodiment of the invention;
[0017] FIG. 3B is a schematic side view of one of the ballast tanks shown in FIG. 3A illustrating placement of nozzles and illustrating mixing of water according to an embodiment of the invention;
[0018] FIG. 3C is a schematic perspective view of the ballast tank of FIG. 3B according to an embodiment of the invention;
[0019] FIG. 4A is a schematic cross-sectional view of a cargo ship having a double-bottom ballast tank with width-to-height ratios that preclude establishment of a sufficient number of rotating fluid cells or vortexes;
[0020] FIG. 4B is a schematic top view of the double-bottom area of the ballast tank of FIG. 4A showing placement of a nozzle at an entrance of a pipe and mixing of water according to an embodiment of the invention;
[0021] FIG. 4C is a schematic perspective view of a seaward wall section of one of the ballast tanks shown in FIG. 4A illustrating placement of nozzles according to an embodiment of the invention;
[0022] FIG. 5 is a schematic perspective view of a portion of a seaward section of the ballast tanks shown in FIGS. 3C and 4C according to an embodiment of the invention;
[0023] FIG. 6A is a diagram showing flow of water from pumps to nozzles according to an embodiment of the invention;
[0024] FIG. 6B is a graph illustrating determination of establishment of circulation currents in a ballast tank;
[0025] FIG. 7A is a schematic cross-sectional view of a ballast tank illustrating control of flow of water from a submersible pump to a nozzle according to an embodiment of the invention;
[0026] FIG. 7B is a schematic top view of the ballast tank shown in FIG. 7A according to an embodiment of the invention;
[0027] FIG. 8 is a schematic, cross-sectional view of a ballast tank showing placement of a jet pump on a deck of a ship according to an embodiment of the invention;
[0028] FIG. 9 is a diagram showing a fire suppression pump in an engine room of a ship used to provide water to the nozzle mixing system in a ballast tank according to an embodiment of the invention;
[0029] FIG. 10A is a diagram illustrating control of flow of water to nozzles using a single valve according to an embodiment of the invention;
[0030] FIG. 10B is a diagram illustrating control of flow of water to nozzles using multiple valves to achieve intermittent or continuous operation of all nozzles together according to an embodiment of the invention;
[0031] FIGS. 11A and 11B are schematic diagrams showing alternative nozzle configurations according to embodiments of the invention;
[0032] FIGS. 12A and 12B are diagrams showing alternative configurations for controlling operation of a valve that supplies water to a nozzle to achieve intermittent or continuous flow through the nozzle according to an embodiment of the invention;
[0033] FIG. 13A is a schematic top view of a ballast tank illustrating placement of three nozzles according to an example of an embodiment of the invention;
[0034] FIG. 13B is a schematic side view of the ballast tank of FIG. 13A ;
[0035] FIG. 14A is a schematic top view of a ballast tank illustrating placement of two nozzles according to an example of an embodiment of the invention;
[0036] FIG. 14B is a schematic side view of the ballast tank of FIG. 14A ;
[0037] FIG. 14C is a schematic perspective view of the nozzle arrangement shown in FIG. 14A ; and
[0038] FIG. 14D is a schematic plan view of the nozzle arrangement shown in FIG. 14C .
DETAILED DESCRIPTION
[0039] FIG. 1 is a schematic perspective view of a nozzle mixing system 100 employed in a typical ballast tank 105 having a seaward wall 110 , a double-bottom area 115 , and a water level 117 . The nozzle mixing system 100 uses one or more nozzles 120 strategically placed inside the ballast tank 105 to deliver jets 125 of water. The type of nozzles 120 , location of the nozzles 120 , and volume and pressure of the water coming from the nozzles 120 create a circulation current 130 inside the tank 105 . The currents 130 developed by the transfer of the energy from the water jets 125 delivered by the nozzles 120 to the water in the ballast tank 105 result in complete mixing of all the water in the ballast tank 105 in a relatively short time (i.e., a few hours). The design of the nozzle mixing system 100 is dependent on the geometry and size of the particular ballast tank that is being mixed. The nozzle type, location of the nozzles in the tanks, and the pressure and volume of water delivered to the nozzles are a function of the environment in which the nozzles will be implemented.
[0040] The nozzles 120 can be permanently installed in the ballast tank 105 when it is empty, or they can be lowered into the tank 105 before filling, during filling, or when it is full of water through inspection/access ports 135 located in the top of the tank 105 . The inspection/access ports 135 are accessible from the deck of the ship or through other hatches or openings in the bulk heads that may separate various components of the ballast tank. This latter type of deployment does not require any modification to the ship. Water is conveyed to the nozzles 120 through pipes/hoses 140 . Water to supply the nozzles 120 can be obtained from 1) an existing firefighting water supply system on the ship, 2) a submersible pump lowered into the ballast tank 105 , 3) a pump drawing water through a bulkhead connection into the lower portion of the ballast tank 105 via access through the maintenance or conveyor tunnels found on most cargo ships, and 4) inline pumps on the deck of the ship, such as jet pumps, diaphragm pumps, axial flow pumps, turbine pumps, gear pumps, piston pumps, centrifugal pumps, etc. Water supply to the nozzles is discussed in greater detail below.
[0041] The double-bottom area 115 is typically only about five feet to six feet in height depending on the construction of the ship. Previous mixing methods have had difficulty mixing the water in double-bottom areas. However, the nozzle mixing system 100 generates hydraulic mixing of all portions of the tank 105 , as explained below.
[0042] The objective of using nozzles for mixing is to impart an impulse force F from a single or multiple set of nozzles to provide the power needed to overcome resistive forces related to fluid drag over tank components by the receiving flow in motion. Multiple versus single nozzles operate at relatively high energy transfer efficiencies, and moderate velocity through the nozzles provides superior transfer efficiencies when compared to very high velocities through the nozzles. Further, establishing a rotary circulation or vortex within the tank is desirable to minimize mixing time rather than creating flow patterns that result in distorted non-circular or rectangular flow cells. Non-circular or rectangular flow cells act to establish bidirectional or opposing flow fields and thus increase power requirements due to fluid shear. Ship ballast tanks are not designed for optimal mixing. Rather, they are designed to add strength to the hull of the ship to withstand roll, pitch, and yaw forces while retaining liquid ballast volumes needed for stability. The nozzle mixing system 100 exploits the structure of ballast tanks, particularly transverse structural web frames, to avoid the drag related to bidirectional flow, as well as to help approximate mixing circulation cells that are stable, predictable, and that require reasonable levels of energy input.
[0043] FIG. 2A is a schematic cross-sectional view of a cargo ship illustrating two ballast tanks 205 a and 205 b, each having a double-bottom area 210 a and 210 b, respectively. The tanks 205 a and 205 b are structurally isolated from one another, and have dimensions of, for example, about 140 feet in length, 50 feet in width, and 30 feet in depth. Each of the ballast tanks 205 a and 205 b illustrates two different nozzle orientations. Nozzle 215 in tank 205 a is oriented horizontally, and nozzle 220 in tank 205 b is oriented vertically. Flow from the nozzles 215 and 220 transfers energy either horizontally or vertically, respectively, to establish transverse rolls 225 a and 225 b within the tanks 205 a and 205 b.
[0044] FIG. 2B is a schematic top view of the tank 205 a. In the embodiment shown in FIG. 2B , three nozzles 215 a, 215 b, and 215 c divide the tank 205 a into three mixing cells that impart energy and flow into the hard to mix double-bottom area 210 a. Water is not jetted directly into the double-bottom area 210 a because this results in rapid energy dissipation due to the presence of regularly spaced stiffeners and bulk heads (not shown) in the double-bottom area 210 a, although in some cases this may result in enhanced mixing depending on the geometry of the tank and nozzle orientation. Water moves in and out of the double-bottom area 210 a and between sections within the double-bottom area via lightening holes 217 in web frames 219 . FIG. 2C is a schematic perspective view of tank 205 b with nozzles 220 a, 220 b, and 220 c located near the bottom of the tank.
[0045] The arrows in FIGS. 2A to 2C show that the energy transferred from the water delivered by the nozzles, in either orientation, to the water in the tanks 205 a and 205 b establishes transverse flow and circulation currents to facilitate complete mixing of all water in the tanks 205 a and 205 b.
[0046] FIGS. 3A , 3 B, and 3 C illustrate mixing of L-shaped ballast tanks. FIG. 3A is a schematic, cross-sectional view of a cargo ship with two L-shaped ballast tanks 305 a and 305 b having seaward sides 310 a and 310 b and double-bottom areas 315 a and 315 b , respectively. Tank 305 b shows the placement of a nozzle 320 in a vertical orientation. FIG. 3B is a schematic side view of the seaward wall of the tank 305 b and FIG. 3C is a schematic perspective view of the tank 305 b, both illustrating placement of three nozzles 320 a, 320 b , and 320 c. The nozzles 320 a, 320 b, and 320 c operate vertically in this embodiment to induce flow laterally among transverse web frames 325 that are coupled, hydraulically, by lightening holes 330 in the web frames 325 . The surfaces of the web frames 325 prevent drag related to opposing flow streams and hence provide for mixing with relatively low power requirements.
[0047] The arrows in FIGS. 3A to 3C show that the energy transferred from the water delivered by the nozzles 320 a, 320 b, and 320 c to the water in the tank 305 b establishes a transverse flow and circulation current to facilitate complete mixing of all water in the tank 305 b. Water moves in and out of adjacent areas through the lightening holes 330 in the web frames 325 between the tank sections. The circulation currents in the vertical part of the tank 305 b pull water out of the double-bottom area 315 b as shown in FIG. 3A . Mixing of the double-bottom area 315 b is not depicted in FIG. 3C .
[0048] FIGS. 4A , 4 B, and 4 C illustrate mixing of a double-bottom ballast tank 405 that has a width to height ratio that precludes the establishment of a sufficient number of rotating fluid cells or vortexes. FIG. 4A is a schematic cross-sectional view of a cargo ship having the ballast tank 405 , a double-bottom area 410 , two seaward wall sections 415 a and 415 b, a pipe 420 , and a nozzle 425 . FIG. 4B is a schematic top view of the double-bottom area 410 showing a nozzle 430 at an entrance of the pipe 420 , web frames 435 between tank sections, and lightening holes 440 . FIG. 4C is a schematic perspective view of the seaward wall section 415 b illustrating placement of nozzles 425 a, 425 b, and 425 c.
[0049] Mixing is achieved in this embodiment by using the nozzle 430 to direct water from one end of the tank 405 to the opposite end, which forces water to move through each tank subsection via the lightening holes 440 in the web frames 435 to complete a circulation cell. In the double-bottom area 410 , the nozzle 430 directs water inside the pipe 420 and the energy at the end of the pipe 420 causes water to move between adjacent areas through the lightening holes 440 in the web frames 435 . Mixing in this type of tank occurs due to displacement and dispersion and typically requires two to four complete exchanges to ensure complete mixing of all the water in the tank. There is only one double-bottom ballast tank shown in FIGS. 4A to 4C . For a ship having two double-bottom tanks that are nearly hydraulically isolated, mixing is achieved by implementing the embodiment shown in FIG. 4B in each of the separate tanks.
[0050] The arrows in FIGS. 4A to 4C show that the energy transferred from the water delivered by the nozzles 430 , 425 a, 425 b, and 425 c to the water in the tank 405 is sufficient to establish a transverse flow and circulation current to facilitate complete mixing of all water in the tank 405 .
[0051] FIG. 5 is a schematic perspective view of a portion of the seaward section of the ballast tanks shown in FIGS. 3C and 4C . For purposes of illustration, seaward wall section 415 b is discussed in relation to FIG. 5 . The arrows show that the movement of water resulting from the energy transferred from the water delivered by any of the nozzles, for example, the nozzle 425 b, to the water in the tank section 415 b establishes a transverse flow and circulation current to facilitate complete mixing of all water in the tank section 415 b . The transfer of energy causes water to move between adjacent areas through the lightening holes 440 in the web frames 435 between the tank sections.
[0052] Ballast tanks are engineered to be part of the structure of the ship and are integral to the stability and integrity of the ship. As a result there are often multiple types of ballast tanks on a ship that are geometrically complex depending on the baffles and support structures inside the tank. Of the approximately 70,000 ships currently engaged in global trade, the variety of tank geometry is vast.
[0053] The nozzle mixing system disclosed herein uses currents developed by the transfer of energy from the water delivered by the nozzles to the water in any tank to completely mix all water in the tank in a relatively short time to facilitate the introduction of biocides and biocide neutralizing agents within the tank so the water can be treated, tested and de-ballasted in accordance with ballast discharge standards. This system does not require the water to be removed from the tank and delivered to a separate mixing and treating system located on or off the ship. Rapid mixing is required since some biocides being considered for killing invasive species have a short half-life. Thorough mixing of the water in the tank requires specifying the type of nozzles used, the locations of the nozzles in the tank, and the pressure and volume of water delivered to the nozzles. All of these specifications are a function of the environment in which the nozzle mixing method is implemented.
[0054] The number of nozzles used is determined by the geometry of the particular ballast tank and the shape and abundance of the internal web frames in the tank. The embodiments shown in FIGS. 2C , 3 C, and 4 C show the use of three nozzles to establish the necessary energy to mix the portion of the tank that is adjacent to the seaward wall of the side of the ship. However, if the tanks are longer or contain more internal web frames, more nozzles may be required. Ultimately, the objective is to install the minimum number of nozzles needed to mix the tank in an efficient and timely manner with the minimum energy input into the mixing system.
[0055] The placement of the nozzles is dependent upon the environment in which they will be used. Ultimately, the type, location, and pressure and volume of the water delivered to the nozzles is designed to generate a vertical circulation current in the tank that mixes all the water in the tank in a relatively short time. The currents that are established by the nozzles result in water being pulled out of areas in the tank that are otherwise isolated by the baffles and support structures inside the tank.
[0056] The location of the nozzles is based on the geometry of the tank, the water level in the tank, and the shape and abundance of internal web frames in the tank. Simply placing nozzles on the sides or bottom of a tank will not ensure complete mixing of the water in the tank. The nozzles need to be strategically placed to ensure complete mixing. Also, simply using pumps to draw water from one part of the tank and reintroducing water back into the tank, thereby establishing a circulation loop, results in inconsistent results, extended periods of time to ensure complete mixing, and requires specialized pumps, hoses, pipes, and expensive retrofitting to the ship's infrastructure.
[0057] Minimizing the amount of energy the nozzle mixing system requires and the weight of the system is a primary objective given (1) the limited energy resources and high cost of energy available on board the ship, and (2) the need to subtract equipment weight from cargo potential of the ship. Equipment weight and power requirements can be reduced by imparting a strategy of intermittent nozzle operation, rather than the standard continuous operation mode, during the treatment period.
[0058] Intermittent operation is achieved by diverting water, for example, from a single submersible pump located in the ballast tank alternately to one or the other of a strategically positioned pair of nozzle assemblies within the same tank. Water routing is achieved through use of powered on/off or 3-way control valves regulated by a time-based control system, such as a programmable logic controller (PLC). Switching frequencies and duration are related to system volume, geometry, and nozzle operating conditions and thus are dependent upon the particular ballast tank. The mixing rate in different regions of the ballast tank is optimized by altering nozzle activation times when one side of the tank has more drag-related structure than the other side. Alternatively, a single nozzle or group of nozzles served by a single dedicated pump can operate intermittently by intermittently powering the pump with a time-based controller that regulates electrical service.
[0059] Energy transfer improves as velocity differentials between the bulk circulating flow and the nozzle velocity increases. Given hydraulic drag effects within the tank will slow bulk fluid velocities after nozzle flow has been terminated, reactivation of the nozzles, intermittently, will result in nozzle flows interacting with bulk flows that are not constant but vary with time and are relatively low, on average. Further, once the bulk circulating flow is established, the kinetic energy of the bulk flow will allow for the continued mixing and blending once nozzle flows have been redirected or terminated.
[0060] The location and number of pumps supplying water to the nozzle(s) can also be optimized to minimize the energy requirements of the mixing system and ensure complete mixing in areas of the tank that are nearly hydraulically isolated. Geometrically complex tanks often result in areas in the tank that are somewhat isolated and difficult to mix. For these tanks, using a single pump could be more efficient than using two pumps located in separate areas of the tank. A single pump located in the area that is difficult to mix would be used to draw water from this area and deliver it to one or more nozzles located elsewhere in the tank. The energy transferred from the nozzles to the water in the tank would result in water circulating back into the area where the pump is located. A pump drawing water from an area that is difficult to mix to supply water to nozzles in other locations combined with the mixing effect of the rotary circulation currents generated by the nozzles is sufficient to thoroughly mix all areas of the tank in an efficient manner with a single pump.
[0061] FIG. 6A is a diagram showing a Programmable Logic Controller (PLC) 605 used to control the flow of water from one or more pumps 610 to the nozzles, such as nozzles 424 a, 425 b, and 425 c illustrated in FIG. 4C , through valves 615 , 620 , and 625 . The PLC 605 is a time-based or time-based plus velocity-based controller positioned outside of the ballast tank. A return signal may be used at the PLC 605 to indicate valve positions. Lines 626 , 627 , and 628 transmit power source/signals respectively to each of the on/off valves 615 , 620 , and 625 used to control the flow of water from the pump 610 to the nozzles 425 a , 425 b, and 425 c. The number of nozzles used depends upon the application of the mixing technology.
[0062] Also shown in FIG. 6A is a flow sensor 630 that can be used in the tank to provide a signal back to the PLC 605 . FIG. 6B is a graph illustrating that the flow sensor 630 can be used to determine when circulation currents have been established in the tank (as represented by curve 645 ) and to turn the supply of water on and off as needed (as represented by curves 645 - 650 - 645 - 650 , etc. in succession) to maintain the necessary flow from the nozzles to keep the circulation currents established. Turning the system on and off minimizes energy consumption of the system but maintains the velocities necessary for mixing. The flow sensor 630 in the tank can be used to indicate the condition of the bulk solution velocity and can be used to signal turning the valves 615 , 620 , and 625 on and off to minimize the energy needs of the mixing system.
[0063] FIG. 7A is a schematic cross-sectional view of a typical ballast tank 705 showing a power supply 710 , the PLC 605 , and a power line 715 to a submersible pump 717 . Water from the pump 717 moves to a nozzle 720 through pipes/hoses 725 .
[0064] FIG. 7B is a schematic top view of the ballast tank 705 . The PLC 605 controls valves 730 and 735 and the submersible pump 717 . Water moves from the pump 717 , through the valves 730 and 735 , to the nozzles 720 and 740 through the pipes/hoses 725 . The single pump 717 in this embodiment can supply water to both nozzles 720 and 740 simultaneously or one at a time, alternately, as directed by the PLC 605 . Alternating operation of the nozzles 720 and 740 can reduce the energy demands of the system as discussed above. Alternative locations of the pump, shown as pump 717 a and 717 b, can be used to minimize the energy requirements of the mixing system and ensure complete mixing in areas of the tank 705 that are nearly hydraulically isolated. A single pump, such as pump 717 a or 717 b, located in an area that is difficult to mix can be used to draw water from this area and deliver it to one or more nozzles located elsewhere in the tank 705 .
[0065] FIG. 8 is a schematic, cross-sectional view of a ballast tank 805 showing placement of a jet pump 810 on the deck of a ship. Using the jet pump 810 eliminates the need to supply electrical power down into the tank 805 that would otherwise be needed if a submersible pump is used. In this embodiment, the power supply 710 supplies power to the PLC 605 that controls operation of the jet pump 810 . Water is drawn from the tank 805 through an inlet 815 containing a check valve. Recirculating flow in two parallel lines 820 and 825 is used to supply water to a nozzle 830 through a pipe/hose 835 . To establish recirculating flow in lines 820 and 825 , line 820 is primed with water from a surface-supplied line such as a hose from the ship's fire suppression system.
[0066] FIG. 9 is a diagram showing a fire suppression pump 905 in the engine room of the ship used to provide water to the nozzle mixing system in a ballast tank 910 . Water is drawn from the ballast tank 910 by the pump 905 used for the ship's fire suppression system 915 . A hose/pipe 920 is used to bypass water through a valve 925 that is controlled by the PLC 605 .
[0067] FIGS. 10A and 10B are diagrams showing alternatives to controlling flow of water to nozzles. In FIG. 10A , water from a pump 1005 is controlled by a single valve 1010 that is operated by the PLC 605 . Water flows from the valve 1010 through a manifold 1015 to achieve intermittent or continuous operation of all nozzles 1020 together. In FIG. 10B , additional valves 1025 controlled by the PLC 605 are added between the manifold 1015 and the nozzles 1020 to achieve independent operation of the nozzles intermittently or continuously.
[0068] FIGS. 11A and 11B are schematic diagrams showing alternative nozzle configurations. In FIG. 11A , a single nozzle 1105 is used to convey water from a pump 1110 into the ballast tank. In FIG. 11B , multiple smaller nozzles 1115 are used to convey water from the pump 1110 into the ballast tank. The thrust generated by the nozzles (which can be significant) should be considered when installing them in the ballast tank to ensure that they remain in the desired locations and orientations. Those familiar with fluid mixing will understand that there are various ways to negate nozzle thrust.
[0069] FIGS. 12A and 12B are diagrams showing alternatives for controlling the operation of a valve 1205 that supplies water to a nozzle 1210 to achieve intermittent or continuous flow through the nozzle 1210 . In FIG. 12A , the PLC 605 is attached to a submersible pump 1215 and the valve 1205 by a signal/power source cable 1220 . To actuate and control the pump 1215 and the valve 1205 , the PLC 605 sends and receives electricity through the cable 1220 . A configuration that eliminates installation of electrical components underwater in the ballast tank is shown in FIG. 12B . In this embodiment, water is delivered through the valve 1205 to the nozzle 1210 via a pipe/hose 1225 from a jet pump 1230 located on the deck of the ship. The valve 1205 is operated by a pneumatic controller 1235 on the deck of the ship that is controlled by the PLC 605 . An air line 1240 connects the pneumatic controller 1235 and the valve 1205 . Controlling the operation of the valves to supply water to the nozzles to achieve intermittent or continuous flow through the nozzles can be applied to any of the embodiments described above.
[0070] The advantages of the nozzle mixing system disclosed herein include the following:
[0071] 1) the components of the nozzle mixing system are inexpensive;
[0072] 2) there are few parts that require maintenance or repair;
[0073] 3) the nozzle mixing system needs relatively inexpensive redesign or modification to the ship compared to dedicated pre- or post-treatment systems that are integrated into the infrastructure of the ship;
[0074] 4) if permanent installation is desired, the installation and maintenance of the nozzle mixing system as a permanent part of the ship's infrastructure is inexpensive;
[0075] 5) the nozzle mixing system is portable and can be moved from tank to tank as needed so one system can be used to mix multiple tanks onboard a ship, and the portability of the nozzle mixing system facilities its use in emergency situations such as groundings;
[0076] 6) the nozzle mixing system can be integrated with the existing firefighting system on board the ship to reduce the amount of equipment needed to implement the system;
[0077] 7) the nozzle mixing system can be modified to mix different ballast tank configurations;
[0078] 8) the nozzle mixing system can be used to introduce biocides into the ballast tanks by injecting the biocide into the stream used to supply water to the nozzles;
[0079] 9) the ballast tank water does not need to be continuously removed, sent through a treatment system, and returned to the tank—complete mixing can be achieved with the nozzles alone; and
[0080] 10) the nozzle mixing system can mix and treat the contents of a tank faster than conventional systems can mix a tank.
[0081] Thus, application of the nozzle mixing system can reduce the worldwide spread of aquatic invasive species and the environmental and economic impact they can cause.
EXAMPLES
[0082] Examples will now be described in detail below that serve to illustrate embodiments of the nozzle mixing system and method described herein. However, it will be understood that the present invention is in no way limited to the examples set forth below.
Example 1
[0083] The nozzle mixing system was tested in a ballast tank having a double-bottom area. Ballast tanks having double-bottom areas are commonly found on many ships. The placement of the nozzles determines the necessary energy to establish circulating currents that result in pulling water out of the double-bottom area.
[0084] Example 1 is illustrated in FIGS. 13A and 13B . FIG. 13A is a schematic top view of a ballast tank 1302 with three nozzles 1305 a, 1305 b, and 1305 c and a double-bottom area 1310 . FIG. 13B is a schematic side view of the ballast tank 1302 . The nozzle mixing system and method was tested on the ship the Indiana Harbor (American Steamship Company, Williamsville, N.Y.) in ballast tank #4 on the starboard side. The ballast tank had a length L of 144 feet, a width W of 39 feet, and a height H of 45 feet. The double-bottom area 1310 had a height DBH of 31 inches and a width DBW of 9 feet, 9 inches. The tank had 17 web frames that were each 4 feet high and spaced every 8 feet. The depth of water in the tank was 20 feet.
[0085] The nozzles were mounted at a height NH of 88 inches from the bottom of the tank 1302 on the inside of seaward wall 1315 with the nozzles pointing towards mid-ship. To determine the position of the three nozzles 1305 a, 1305 b, and 1305 c laterally, the overall length of the tank was divided by three and each of the nozzles was respectively placed at approximately the center of each one-third portion of the length of the tank 1302 . In Example 1, the nozzle 1305 b was placed at the middle of the length L of the tank, nozzles 1305 a and 1305 b were placed at a distance D 1 of 47 feet, respectively, on either side of the nozzle 1305 b, leaving a distance D 2 of 25 feet at the forward and aft ends of the tank. The height and lateral positions of the nozzles were sufficient to establish the desired mixing and circulation currents in the tank.
[0086] Each nozzle had a ¾-inch diameter nozzle orifice. A 3-inch diameter hose supplied water to each nozzle at a rate of 110 gallons per minute (GPM) at 50 pounds per square inch (PSI) at the nozzle outlet, and 330 GPM total.
[0087] Tank mixing was completed in less than 1.5 hours.
[0088] Example 2
[0089] The Indiana Harbor was also used for the second example, with the same ballast tank dimensions as in Example 1. Example 2 is illustrated in FIGS. 14A to 14D . FIG. 14A is a schematic top view of a ballast tank 1402 with two nozzles 1405 a and 1405 b and a double-bottom area 1410 . FIG. 14B is a schematic side view of the ballast tank 1402 of FIG. 14A . FIG. 14C is a schematic perspective view of arrangement of the nozzles 1405 a and 1405 b. FIG. 14D is a schematic plan view of the nozzle arrangement shown in FIG. 14C .
[0090] As shown in FIG. 14A , the nozzles 1405 a and 1405 b are located laterally in the center of the tank 1402 along a seaward wall 1415 . The height of each of the nozzles 1405 a and 1405 b from the bottom of the tank 1402 differs, as shown in FIGS. 14B and 14C . A pipe/hose 1420 conveys water to the nozzles 1405 a and 1405 b. The nozzle 1405 a at the end of the pipe/hose 1420 is located at a height H 1 of 97 inches from the bottom of the tank. Pipe fittings (not shown) that connected the bottom nozzle 1405 a to the top nozzle 1405 b resulted in the top nozzle 1405 a being 13 inches above the bottom nozzle 1405 b, placing the top nozzle 1405 b at a height H 2 of 110 inches from the bottom of the tank 1402 .
[0091] The orientation of the nozzles 1405 a and 1405 b relative to each other and the seaward wall 1415 of the tank 1402 is shown in FIG. 14D . The nozzles 1405 a and 1405 b were oriented at an angle A 1 of 90° from one another and at an angle A 2 of 45° from the seaward wall 1415 of the tank 1402 . Each nozzle had a ⅞-inch diameter nozzle orifice. A 4-inch diameter hose supplied water to each nozzle at a rate of 150 GPM at 50 PSI at the nozzle outlet, and 300 GPM total.
[0092] Tank mixing was completed in less than 2 hours.
[0093] The type, location, and pressure and volume of the water delivered to the nozzles during the tests are applicable for many ballast tank configurations. However, smaller tanks that are not geometrically complex will require fewer nozzles and lower volume and pressure of water delivered to the nozzles. Likewise, larger tanks that are geometrically complex may require more nozzles and may also require higher volume and pressure delivered to the nozzles.
[0094] Thus, it will be appreciated by those skilled in the art that modifications and variations of the present invention are possible without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
REFERENCES CITED
[0000]
Bureau of Transportation Statistics 2007 (2008) Washington, D.C. United States Department of Transportation, Research and Innovative Technology Administration http://www.bts.gov/publications/maritime trade and transportation/2007/pdf/entire.pdf.
Carlton, J. T., Reid, D. M. and Leeuwen, H. van. 1994. The role of shipping in the introduction of nonindigenous aquatic organisms to the coastal waters of the United States (other than the Great Lakes) and an analysis of control options. The National Biological Invasions Shipping Study (NABISS). U.S. Coast Guard and National Sea Grant Program.
Carlton, J. T. 1985. Transoceanic and interoceanic dispersal of coastal marine organisms: the biology of ballast water. Oceanogr. Mar. Biol. Ann. Rev. 23: 313-371.
Carlton, J. T. and Geller, J. B. 1993. Ecological roulette: the global transport of nonindigenous marine organisms. Science 261: 78-82.
Chesapeake Bay Commission. 1995. The introduction of nonindigenous species to the Chesapeake Bay via ballast water. Chesapeake Bay Commission, Annapolis, Md. 28 p.
Chu, K. H., Tam, P. F., Fung, C. H., and Chen, Q. C. 1997. A biological study of ballast water in container ships entering Hong Kong. Hydrobiologia 352: 201-206.
Elton, C. S. 1958. The ecology of invasions of animals and plants. Methuen and Company, Ltd., London. 181 pp.
Mooney, H. A. and Drake, J. A. (eds). 1986. Ecology of biological invasions of North America and Hawaii. Springer-Verlag, New York
National Academies of Science (NAS) 1996. Stemming the tide: controlling introductions of nonindigigenous species by ships' ballast water. Marine Board Committee on Ships' Ballast Operations. National Academies Press, Wash. D.C., 160 p. ISBN: 0-309-58932-0
Office of Technology Assessment Archive, 1993. Harmful Non-Indigenous Species in the United States, September 1993, OTA-F-565,NTIS order #PB94-107679,GPO stock #052-003-01347-9
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A system, method, and apparatus for treating ship or barge ballast water. The system includes a ballast tank storing ballast water and one or more nozzles located in the ballast tank. One or more pumps supply a chemical into the ballast tank and water to the nozzles. The nozzles are strategically located in the ballast tank to circulate the ballast water and mix the chemical with the ballast water without removing the ballast water from the ballast tank to a separate mixing and treatment area located outside the tank either onboard or off of the ship or barge.
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REFERENCE TO A RELATED APPLICATION
This application is a continuation-in-part of allowed U.S. Ser. No. 004,658, filed Jan. 20, 1987 now U.S. Pat. No. 4,730,415.
BACKGROUND AND SUMMARY OF THE INVENTION
This mechanical invention relates generally to edge guards, and more particularly it relates to novel non-metallic edge guards, for use such as on the trailing edge of swinging closures.
Edge guards are used as protective and decorative articles on the edges of objects. In the case of a swinging closure of an automotive vehicle such as an automobile door, an edge guard which is applied to the trailing edge of the swinging closure can provide not only decoration, but also protection when the trailing edge is swung against an object. The edge guard can provide protection not only for the trailing edge of the swinging closure, but also for the object which is struck by the trailing edge of the swinging closure. That is not to say that an edge guard can protect and withstand substantial impacts, but edge guards are useful in preventing chipping, knicking, scratching and like damage which typically arises in regular everyday use of an automobile, for example the opening and closing of a car's doors in a confined space such as in a crowded parking lot.
Applicant is the inventor of many edge guard improvements over the years. These improvements are the subjects of many patents. For the most part, these patented improvements relate to metallic edge guards, or insulated metallic edge guards. Metal possesses superior decorative and function characteristics, and the insulated metallic edge guards advantageously combine the benefits of metallic and non-metallic components.
Although Applicant continues to prefer the insulated metallic type of edge guard for automotive use because of the combination of benefits which it provides, he has discovered ways to improve upon non-metallic edge guards in several ways which can be useful for certain applications. These improvements in non-metallic edge guards are the subject of this patent application
Non-metallic edge guards are not broadly new. Examples exist in prior patents such as U.S. Pat. No. 3,547,516 and U.S. Pat. No. 4,372,083. While these prior non-metallic edge guards claim to possess certain beneficial characteristics, the truth of the matter is that in practice they are difficult to install, especially on contoured edges, and once installed they may not retain satisfactorily over the life of the automobile. More especially, the improved body fit programs of the automobile manufacturers in recent years renders it difficult to fit the non-metallic edge guards onto the doors without interference with the door frame openings when the doors are closed.
The present invention is directed to new and useful improvements in non-metallic edge guards which render them superior to the prior non-metallic edge guards. These improvements relate to the ability to give satisfactory fit, retention, decoration and protection. Details of the improvements will be seen in the ensuing description and claims which should be considered with the accompanying drawings. The drawings disclose a preferred embodiment in accordance with the best mode contemplated at the present time in carrying out the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1-22 are longitudinal end views of the non-metallic bodies of different embodiments of edge guards according to the invention.
FIGS. 23-44 are end views corresponding to FIGS. 1-22 of the completed edge guards.
FIGS. 45-48 are views illustrating a method of making the edge guards.
FIG. 49 is a perspective view illustrating a step in the method, and FIG. 50 is an enlarged sectional view along line 50--50 in FIG. 49.
FIG. 51 is a modified form of FIG. 50.
FIG. 52 is a view illustrating a representative installation of an edge guard, and FIGS. 53 and 54 are modified forms of edge guards for facilitating installation on contoured edges.
FIG. 55 is a longitudinal end view of a further embodiment of edge guard.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the several views wherein like reference numerals designate like parts, the edge guard 100 comprises a non-metallic body 102 and a much thinner outer layer 104 applied at least to the exterior of body 102. The body comprises a curved base 106 and legs 108, 110 which extend from base 106, thereby giving the edge guard a general U-shaped or V-shaped cross section which is open in varying degrees as portrayed by the several drawing figures. FIGS. 1-22 show various bodies 102. In some figures the legs are of different lengths; in others they are the same length.
The bodies are formed with various notching patterns for reception of layer 104 in various ways. The notching is designated, generally, by the numeral 112 and corresponds in thickness essentially to the thickness of layer 144. In some embodiments the notching comprises an undercut 114, in others one or more slots 116, and in still others a combination of both. There are various configurations of notching and slotting.
In general, the undercutting 114 extends along a substantial portion of the outside of at least one of the legs and partially into the base. The slotting in general takes place adjacent the distal end of a leg, on either the interior or the exterior face of the body, and is at an angle to the length of the corresponding leg. FIGS. 1-22 show various forms of bodies containing various patterns of undercuts 114 and slots 116.
FIGS. 23-44 show the finished edge guards after the layers 104 have been joined to the bodies. The layers fully occupy the zones of notching, and where there are slots in the body, the margins of the layers are inserted into the slots. Hence, layers 104 cover the exterior of the body along at least a portion of the base and a substantial adjoining portion of a leg adjacent the base. The layers also possess flushness in relation to body 102 in the finished edge guard.
Certain of the embodiments of edge guard bodies have essentially uniform thickness throughout their legs and base. FIG. 2 is an example. Other embodiments, however, have a reduced thickness base such as FIG. 1, for example. The reduced thickness base is advantageous in securing better conformance and fit especially where the extent of the base exceeds 180°, although the reduced thickness base can be useful in embodiments, such as FIG. 22, where the extent of the base is less than in FIG. 1. The illustrated shape of reduced thickness bases is advantageous from manufacturing and use standpoints. It involves a gradually reducing taper extending from the proximal end of each leg to essentially the mid-point of the base.
FIGS. 45-48 show a method of making the edge guards. The material of body 100 is extruded by a conventional plastic extruder (step 200 in the flat to contain the desired notching pattern. These FIGS. 45-48 illustrate making the example of FIG. 36. The layer 104 is joined to the body in fit to the notching pattern so that the two parts 102, 104 become a unit (step 202). Then the unit is formed to the desired shape such as that portrayed by FIG. 48 (step 204). Preferably adhesive is applied (as a step 208) to the notching before the layer 104 is joined to the body 102 to aid in the joining of the two parts. Since the body is still warm after leaving the extruding step, it is possible that the heat and the characteristics of the respective materials constituting parts 102 and 104 could be suitably joined without the adhesive application step. Likewise it is to be appreciated that the illustrated method, although preferred, is not necessarily the only way to make the finished edge guard. For instance, the body could be extruded directly to the final shape and the layer then applied to the finished shape of the body.
Various plastic materials are suitable for the body; PVC however has certain advantages for certain applications and will probably enjoy the most widespread use. It can be colored to desired colors and can be extruded to different cross sectional shapes with standard equipment containing suitable dies to produce the desired cross section. Moreover, there are adhesives available for use in joining the plastic and the layer 104 and also joining the plastic to an edge of most metallic and/or painted edges onto which the edge guard is installed.
The layer 104 is both decorative and functional. The layer can be made in different colors to match, and or contrast with the color of body 102. The layer also adds a protective character which is not present in the PVC body. Use of a material such as mylar, or PVF, for the layer 104 provides functional attributes of durability and toughness, yet are compatible for joining with PVC through use of conventional joining processes such as those described above.
FIG. 50 illustrates a PVF layer 104 and FIG. 51 illustrates mylar. The mylar is transparent and contains an encapsulated metallic foil. This enables the edge guard to be endowed with a metallic looking appearance.
FIG. 52 shows an edge guard 100 installed on the edge of an automobile door 300. Where the edge is highly contoured, it may be desirable to impart either a U-shape or a V-shape notching pattern 302, 304 as shown in FIGS. 53 and 54 respectively.
FIG. 55 shows a further embodiment of edge guard 400 that bears many similarities to the other preceding embodiments; there are however certain significant differences. The non-metallic body 402 has a general U-shape that is quite similar to body 102 in FIG. 28. It has a layer 404 that is similar to layer 104 in FIG. 28, but layer 404 covers &he exterior of body 402 only along one leg 408 and the adjoining half of the curved base 406. Thus body 402 has an undercut 414 for receiving layer 404. It also has slots 416 for reception of the side edges 418 of layer 404, but these slots 416 are quite shallow. In fact, provision for them need not even be incorporated into the extruding die that is used to create the cross section of body 402 during its fabrication by an extension process. Rather, they can be created in the extruded plastic, before it has fully set, by forcing, or tucking, the side edges 418 of layer 404 into the still somewhat formable material of body 402 at the opposite terminations of undercut 414, as viewed endwise of body 402 Upon body 402 fully setting, the slots 416 that are formed by so embedding the layer's side edges 418 in body 402, are able to retain the edges thereby reducing any tendency toward separation and/or delamination.
Various combinations of heat and/or pressure and/or adhesive may be used to join layer 404 to body 402 in the manner described, any particular combination used being primarily a function of the particular materials for layer 404 and body 402.
A preferred material for body 402 is PVC, and a preferred material for layer 404 is a metal foil that is encapsulated in mylar. By disposing leg 408 on the exterior of the trailing edge of an automobile door, a metallic appearance is presented. Alternately, by disposing the other leg 410 on the exterior of the edge, the color of body 402 is presented. Hence, the single edge guard 400 is capable of presenting either of two different exterior appearances, yielding a savings over having to make and inventory two different models of edge guard, one fully metallic, the other fully the color of the non-metallic body 402.
Although only a single embodiment of edge guard incorporating the specific details of FIG. 55 is disclosed, it should be readily apparent that the specific principles disclosed in embodiment 400 can be incorporated in other cross sectional shapes for the non-metallic body.
The edge guard exhibits the ability to conform to the edge onto which it is installed, but typically lacks the ability to be self-retaining. Consequently, an adhesive is applied to the interior of the body to cover the legs and base so that the entirety of the interior face can be adhered to the edge onto which the edge guard is fitted.
While preferred embodiments of the invention have been disclosed, it will be appreciated that principles are applicable to other embodiments.
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A layer of material is joined to the exterior surface of a non-metallic edge guard body with the side edges of the layer of material slightly embedded into the body to resist delamination.
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BACKGROUND OF THE INVENTION
The invention relates to a slewing device for screw closures, in particular, from plastic materials, for containers and comprising a drive and a torque limiter for controlling power supply to the drive and including a torque sensor and an angle of rotation sensor, and a method of placing screw closures on containers using the slewing device according to the invention.
A slewing device for screw caps or screw closures as well as a method for putting such closures or caps on containers are known (DE-OS 37 15 935). The known slewing mechanism serves for screwing screw caps onto receptacles and observe herein a preset closing moment. A torque limiter prevents exceeding the desired moment. For this purpose a control circuit measures the drive current absorbed by the drive motor of the rotational device and triggers control signals if the current rises to a specific value corresponding to a specific torque of the threaded-on cap or closure, by means of which the drive current of the drive motor is interrupted. Thus one directly affects the energy supply of the drive.
However it was seen that in some cases especially when using solid plastic closures, a secure sealing of the container is not achievable also when presetting a specific closure moment. This applies especially when containers or bottles subjected to an overpressure are to be closed. By presetting a specific closure moment it is in addition possible to damage the mouth region of the container to be closed, especially with glass bottles, which leads to danger for the consumer. Finally it is seen, that the opening moment, meaning torque required for initial opening of the container, is often considerably higher than desired.
It is therefore the task of the invention to create a slewing mechanism as well as a method, by means of which containers with screw closures, especially also those made of plastics material, can be closed, wherein containers subjected to overpressure are closed in a pressure-tight manner however without being damaged in the mouth region and where a specific opening moment is set up.
SUMMARY OF THE INVENTION
This task is solved in a slewing mechanism in which the torque limiter determines the angle of rotation only after a predetermined closing torque is reached. Since the control arrangement or the torque limiter determines to begin with by means of a torque sensor whether a specific closure moment, the application or applied moment, is reached during a closure process, a defined point of departure or point of reference for the additional measurement during the closure process is established. After reaching this application moment the angle of rotation is acquired, through which the screw closure is turned by the slewing mechanism. A particularly sensitive closure of the container is assured by acquisition of the angle of rotation after reaching the application moment. This permits to exclude damage to the mouth area with a high degree of certainty and to assure a very precise observation of a desired opening moment.
In a preferred embodiment of the slewing mechanism or device the control arrangement is laid out in such a way, that the angle of rotation through which the screw cap or screw closure continues to be turned after reaching a predetermined application moment can be limited to a presettable value. This layout of the slewing device results in a particularly sensitive adjustment of the desired closing moment, wherein the predetermined opening moment can be observed very accurately.
In a preferred embodiment form of the slewing mechanism the torque acting upon the screw closure is acquired by means of the control arrangement serving as torque limiter. Herein the current fed to the drive or the voltage applied to the drive of the slewing device is registered. Since the power absorbed by the drive is proportional to the voltage or to the current, the momentary torque can be determined from the momentary value of the current or the voltage. This determination of the moment is particularly easy to perform.
In an additional preferred closure mechanism the chronological change of the tightening moment is determined or registered. If thus the cap or closure suddenly hangs up or tilts when being threaded on, which is recognized by a rapid rise of the moment per unit time, the closure process can be broken off, so that the mouth region of the container is not damaged.
The described task is solved by means of a method in which the screw closure is screwed down until it reaches a predetermined closing moment and, thereafter, an angle of rotation and/or a chronological change is determined. In order to achieve a particularly sensitive control of the desired closure moment, the cap or closure is to begin with threaded onto the container until a predetermined tightening moment, the application moment, has been reached. With this a defined initial state of the closure process is reached. After this the closure or cap continues to be turned through a predeterminable angle of rotation relative to the container. This leads to a secure setup of the desired closure moment, wherein damage to the mouth of the container are to all intents and purposes eliminated.
According to a preferred embodiment form of the method the chronological change of the tightening moment is additionally registered after the application moment has been reached. Obstructions or troubles in the method during this phase, for instance tilting of the closure on the container can thus be safely determined.
Finally an embodiment form of the method is preferred, where the screw closure or cap is threaded on up to attaining a high limiting moment exceeding the closure moment. Subsequently the closure is turned in opposite direction through a predeterminable angle of turn, in order to set up the desired closure moment and with this also a specific opening moment. It is particularly advantageous in this method that containers whose threads have minor damage can also be closed; in this case an increased closure moment must therefore be applied in order to thread the closure onto the container.
Even if the closure is for instance provided with a safety ring a higher torque must be applied when closing, because the closing moment could often already be reached, before the screw closure is in its final position. Through the initially selected high limiting moment a particularly good contact pressure of the seal against the mouth region of the container is assured, so that minor damage is compensated. A particularly good sealing of the container is achieved in this manner.
BRIEF DESCRIPTION OF THE DRAWINGS
Single FIGURE of the drawing shows a schematic view of a slewing device according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The drawing shows a container 1, in this case a bottle, on which a screw cap 3 of a plastics material is to be threaded or screwed on. The closure or cap is gripped by a sketched closing cone 5 of a slewing device 7 and is placed upon the container 1. Herein it is unimportant for the invention, whether the closing cone 5 is turned with respect to the container 1, or whether the closure cone remains stationary and the container 1 rotates.
The closure cone 5 is rotated in this case by a motor 9 serving as a drive, which is supplied with current or voltage through a switching device 11. A sensor 13 is provided between the energy supply and the switching arrangement, which sensor determines the current or the voltage. Basically it is also possible to provide the sensor 13 between the switching device 11 and the motor 9.
A torque sensor 15 determining the torque is allocated to the motor 9 or the closure cone 5, which determines or acquires the closure moment acting upon the screw closure 3. In addition an angle of rotation sensor 17 is allocated to the closure cone 5, which determines the angular position of the cone.
An elongation measuring strip system (DMS) integrated into a not explicitly shown spindle of the motor 5 is preferably used as a torque sensor 15. An opto-electronic incremental transmitter is preferred for angular measurement.
The signals of the current- or voltage-sensor 13, the torque sensor 15 and the angle of rotation sensor 17 are fed to a control arrangement 19 which evaluates and processes the measured values. In addition these signals are fed to a comparator circuit 21. This comparator circuit contains also values M1, M2, M3, M7, and Mo for predetermined tightening moments presettable by suitable actuators as well as specific values W and W1 for predetermined angles of rotation. The output signals of the comparator circuit 21 are fed to a control arrangement 19.
The control apparatus 19 is connected by a control line 23 with the switching device 11 of the motor 9. In addition it is provided with a differential member 25, to which the output signals of the torque- and angle of rotation sensor are fed.
Sensor 13 registering the supply voltage and/or the supply current of the motor 9 serves to determine the torque momentarily generated by the motor, wherein one proceeds from the circumstance that the moment is proportional to the voltage or of the current. By determining the chronological change of the supply voltage or the supply current of the motor the chronological changes of the torque can also be acquired. In this case the torque sensor 15, which is described above, could be eliminated.
In the following the mode of operation of the slewing device 7 as well as the method for closing containers is described in more detail.
Basically the device and the method are suitable for closing any type of container. The use of the device or the method for closing bottles by plastics caps is preferred. The bottles can herein consist of glass or on their part also of a plastics material, for instance PET.
The screw closure 3 is introduced into the closure cone 5 in any random manner, for instance by means of a so-called pick method. Subsequently the closure cone with the screw closure 3 clamped therein is disposed above the container 1 which is to be sealed or closed off. Herein in this case the closure cone 5 rotates relative to the stationary container 1.
The rotating screw closure 1 is now placed upon the container 1. For this purpose an appropriate switching signal is issued by the control arrangement 19 through the control line 23 to the switching device 11 comprising for instance an electronic switch or a relay, so that the motor 9 is supplied with energy. During the tightening of the closure 3 on the container 1 the closure moment or the tightening moment exerted by the motor 9 upon the closure cone 5 or the screw closure 3 is determined. The momentary or instantaneous moment can first of all be determined by the sensor 13, which registers the current or the voltage supply by the energy supplied to the motor 9. It is also possible to determine the moment transferred from the motor 9 to the closure cone 5 by means of a torque sensor 15. The output signal of the sensor 13 or the torque sensor 15 is directed to the control arrangement 19 however also to the comparator 21. The comparator compares the actual momentary value with a predeterminable tightening moment M1, the so-called application moment. As soon as this moment M1 is reached, the angular rotation sensor 17 is activated by the control device 19. The control device 19 now evaluates the signals of the angle of rotation sensor. The actual angle of rotation of the closure cone 5 or the closure 3 is compared in the comparator 21 with a predetermined angular value W. As soon as the closure is additionally screwed down through the desired angle of rotation W after reaching the application moment M1, the control device 19 issues a signal to the switching arrangement 11 through the line 23, so that said switching arrangement interrupts the energy supply to the motor 9. Thus a further turning of the closure is prevented.
If the current- or voltage sensor 13 is utilized, the angle of rotation sensor 17 can be eliminated. The moment supplied by the motor 9 can be determined in such an accurate manner, that the switching arrangement 11 is actuated in such a way through the control arrangement 19 and the control line 23, that the motor 9 is switched off. In a DC motor the torque is proportional to the current or voltage applied to the motor. If only a lower accuracy is desired when reaching the closure moment M2, this method of closing containers is adequate.
If the application moment M1 or the closure moment are not reached, then the following conclusion can be drawn therefrom:
The closure or cap has dropped out of the closure cone prior to reaching the container, no container has been moved beneath the closure cone due to a control error or however the thread of the container or the internal thread of the closure is ruined.
The control arrangement 19 can for instance be provided with a timing member, which presets a specific time within which the application- or the closure moment must have been reached. If this is not the case, a control signal is issued through a signal line S and the container 1 momentarily arranged beneath the closure cone 5 is removed from the closing installation.
Instead of presetting a specific time period, which is allowed at the most to elapse before the application moment M1 is reached, a specific angle of rotation can also be preset. This means the closure is for instance threaded onto the container through a complete revolution. After that the application moment must have been reached. Should this not be the case then one deduces therefrom that damage is present at the container or the closure cap. This particular container is then removed.
If however on the other hand the application moment M1 is reached and the angular rotation sensor 17 has been activated by the control arrangement 19, the closure cone 5 is rotated further, until the momentary angle of rotation reaches the value W entered into the comparator 21. The predetermined angle of rotation W is fixed as a result of tests. Thus it is assured, that the desired closure moment M2 is reached. It is on the one hand assured with such a predetermined closure moment, that the container is closed or sealed by the screw closure 3 in a pressure-tight manner. On the other hand it assures that the opening moment Mo required for initially opening the container is also adhered to.
While the screw closure 3 continues to be turned through the predetermined angle of rotation W, the momentary tightening moment can continue to be monitored by the torque sensor 15 and to be compared in the comparator circuit 21 with a second moment value, a predetermined maximum value of M3. If this maximum value M3 is attained during further turning of the closure, then one can deduce that a defective mouth of the bottle exists. If for instance the threads on the container exterior are nicked, then they cut into the internal wall or the threads of the plastics screw closure 3. The moment required for further turning of the closure thus increases steeply, to such an extent that the predetermined maximum value M3 is exceeded.
If in the course of continued rotation of the closure cone 5 up to attaining the predetermined angle of rotation W, the maximum value of the desired application moment M3 is exceeded, then this can also be due to the internal thread being damaged in the course of its continued extent inside of the screw closure 3. Because of this the cap or closure cannot be screwed on sufficiently far, so that the seal provided there does not come into adequate engagement with the mouth region of the container 1. An internal pressure existing in the container can easily escape. Therefore in such a case a signal is also issued through the control line S of the control arrangement 19, so that this container is separated out of the closing installation. In addition each time when the maximum moment M3 is exceeded prior to the predetermined angle of rotation W being reached, the switching arrangement 11 is actuated in such a way through the control line 23, that the motor 9 no longer drives the closing cone 5. This prevents applying an excessively large torque to the mouth area of the container 1 and that consequently damage occurs.
Finally the maximum tightening moment M3 could be exceeded also prior to reaching the desired angle of rotation W, if the closure or cap 3 tilts on the thread of the container after the application moment M1 has been reached. On the one hand it would also not be assured in that case, that the seal disposed in the cap seals the container pressure in a tight manner, on the other hand, if the closure process is continued because of the tilting, an excessive moment can come to act on the mouth region of the container and cause damage.
A differential member 25 is provided here within the control arrangement 19, which determines the chronological derivation of the output signal of the torque sensor 15 but also of the output signal of the angle of rotation sensor 17.
From an excessively large chronological change of the angle of rotation determined by this differential member 25, it can for instance also be determined when the closure cone 5 suddenly spins or races, that thus screw cap closure 3 is no longer supported on the container 1. This can for instance occur if the side wall of the cap has split or if the thread of the container has failed. In such a case a signal is issued through the control S and the container involved is separated out.
If it is seen that the increase of the torque after reaching the application moment M1 and prior to reaching the desired angle of rotation W is too small, then one can draw therefrom the conclusion, that either the seal in the cap is defective, that the cap was fractured already prior to the application onto the container or that the bottle thread was inaccurately shaped. In any case one can draw the conclusion therefrom, that the cap will race or spin on the container. In this case also the corresponding container is separated out by a signal in the control line S.
If on the other hand the torque rises too rapidly after the application moment M1 has been reached, and prior to reaching the desired angle of rotation W, then one can conclude therefrom, that damage has occurred at the thread of the cap or the container or that the cap or closure has tilted on the container. In this case also a signal is issued through the control line S and the appropriate container is separated out.
Because a maximum torque M3 is preset for the closure process, the opening moment Mo required for initial opening of the container can be adjusted to a desired value. On the other hand additional security is achieved thereby by being able to recognize tilting of the cap or damage to the thread of the cap or the container and being able to separate out the container involved.
Since the torque and on the other hand the angle of rotation after reaching a predetermined application moment can be preset, the moments occurring during closure of a container by a screw closure or cap can be limited. On the one hand damages to the mouth of the container are excluded thereby, on the other hand overloading the closing device is excluded, so that its wear is reduced to a minimum. The useful life of this mechanism is therefore greatly increased.
The method can be modified inasmuch as the screw closure 3 is screwed down by the motor 9 for as long, until reaching a torque limit value Mg is registered by the torque sensor 15 and the comparator 21, which limit value lies above the closure moment M2.
Due to the increased tightening moment containers 1 with slight thread damage can also be securely sealed or closed. Basically it has to be stated, that in case of damage to the thread the closing moment M2 desired in the final analysis is already reached prior to the cap having assumed a final position on the thread of the container, because additional frictional forces are built up due to the damage.
Also when using caps with a warranty or safety ring intended to indicate the initial opening of the closure, frequently the final desired closing moment M2 is already reached prior to the cap having assumed its final position on the container, because the warranty or safety ring produces an additional frictional moment. Therefore when such closures are used a torque must be applied to begin with which exceeds the final desired closing moment M2.
Finally an optimum contact pressure of the seal against the mouth area of the container is also achieved by the increased tightening moment. Thereby the seal espouses the mouth in such a way that, even if the slight damage is present, an optimum sealing of the container is assured even if the contents of the said container are subjected to overpressure.
In order to avoid that excessive opening moments are set up by closing with an increased tightening moment, a reversal of the energy supplied to the motor 9 is achieved after screwing down the cap up to the limiting moment Mg, this by means of a control signal in the control arrangement 19 which is fed to the switching arrangement 11 through the line 23. The motor then reverses its direction of rotation. At the same time the angle of rotation sensor 17 is activated by this control signal. Its output signals are compared in the comparator 21 with an angular value W1 allocated to the left-hand rotation or the opening motion. As soon as the preset angle of rotation lying for instance in the range of 10° to 15° is achieved as soon as the actual angle of rotation thus reaches the limit value W1 present in the comparator 21, the switching arrangement 11 is controlled in such a way by a control signal of the control device 19 through the control line 23, that the energy supplied to the motor 9 is interrupted. Thereby the opening motion of the cap 3 is terminated.
It is determined by tests how far the screw closure or cap must be turned in opposite direction after it has been screwed down up to the limiting moment Mg, until the desired opening moment Mo is set up. The required angle of rotation can depend upon the combination of the materials selected for the container, cap and seal.
Because the switching arrangement 11 can be activated in such a way, that an energy reversal or a pole reversal of the energy supply to the motor 9 is achieved, it is possible that the rotary device of the type described above is controlled in such a way, that in case of a defect occurring during the closure process of a container to begin with a reversal of rotation is performed and the cap is again unscrewed from the container. Then the closing process is started anew. If now an orderly regular closing process is to be set up, the container is left in the normal manufacturing process. Only if a discrepancy occurs again, for instance because the cap or the mouth area of the container are ruined, is the container mustered out of the process. Removals can in this way be reduced to a minimum; such removals entail that additional processing steps must be performed outside of the normal work sequence. Thus an additional improvement of the closing process can be achieved by reversal of the energy supply.
By the availability of the energy reversal it is also possible to turn the cap 3 counter to the closing direction after the first setup on the container 1. In this way an optimum alignment of the thread provided in the cap with respect to the container thread can occur. After a certain left-hand rotation the cap snaps onto the container, which for instance can be determined by an axial motion of the cap with the respect to the container occurring. This motion can be probed by a suitable travel sensor.
The rotation of the cap counter to the closing direction results with screw closures with a warranty- or safety-ring in that said ring is aligned in an optimal manner. This avoids jamming of the safety ring during the subsequent screw-down of the cap.
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A slewing device for screw closures for containers includes a screw closure receiving member, a drive for rotating the receiving member, and a control arrangement for controlling power supply to the drive and including a torque sensor for sensing an instantaneous drive torque, a comparator for comparing the instantaneous drive torque with a closing torque having a predetermined value, and a sensor for sensing an angle of rotation of the receiving member and actuatable only upon the instantaneous drive torque reaching the predetermine value. The method of placing a screw closure on a container includes applying a drive torque to the screw closure to screw it down onto the container, sensing an instantaneous drive torque applied to the screw closure, comparing the instantaneous drive torque with a closing torque having a predetermined value, and sensing an angle of rotation of the screw closure only upon the instantaneous drive torque reaching the predetermined value of the closing torque.
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FIELD OF THE INVENTION
The present invention relates to a method for ensuring the safety of an aircraft flying horizontally at low speed, for example no more than slightly greater than the angle of attack protection speed, said aircraft comprising:
a fixed wing supporting trailing-edge high-lift flaps and engines provided with airscrews, the latter blowing on said wings and said flaps; and a stabilizing horizontal tail group, tilt-adjustable.
BACKGROUND OF THE INVENTION
It is known that, in such a phase of horizontal flight at low speed, the lift imparted on the aircraft by its wings and said flaps, then in the extended position, needs to be high, such that this high lift, reinforced by the blowing on the wings and the extended flaps by the airscrews of the engines and aided by the thrust of said engines, generates a high pitch-down moment relative to the center of gravity of the aircraft.
To balance the aircraft, the pilot deflects said adjustable horizontal tail group to nose up, so that it generates, relative to the center of gravity of the aircraft, a nose-up moment to counteract said high nose-down moment. This balancing nose-up moment must therefore be high, such that the local impact on said adjustable horizontal tail group is strongly negative.
The result is that if, during such a phase of flying horizontally at low speed, the pilot orders a dive, for example to abruptly avoid another aircraft by flying under it to avoid a collision or to rapidly regain speed, the local impact on said adjustable horizontal tail group risks exceeding the stalling effect of the latter, such that, at the moment when the pilot wants to stop the dive maneuver, the adjustable horizontal tail group may have lost its effectiveness: the aircraft will therefore be incapable of priming a flare and this could result in the loss of the aircraft.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to remedy this drawback.
To this end, according to the invention, the method for ensuring the safety of an aircraft flying horizontally at low speed, said aircraft comprising:
a fixed wing supporting engines provided with airscrews, and trailing-edge high-lift flaps, that can be extended and retracted; and a stabilizing horizontal tail group, tilt-adjustable, provided with elevators,
said flaps then being in the maximum extended position and being blown on by said airscrews,
is noteworthy in that said flaps are at least partially retracted when the thrust of said engines is at least equal to a predetermined high value.
Thus, thanks to such a retraction, the blowing effect on said flaps by the airscrews is reduced and said nose-down moment is therefore reduced accordingly. Because of this, the adjustable horizontal tail group must supply a nose-up moment of lower intensity, meaning that the local impact on said adjustable horizontal tail group is less negative and that the latter will be effective at the moment when the flare will be invoked.
According to a first embodiment, which can be qualified as “preventive”, the method according to the present invention is such that said predetermined lift value corresponds to the thrust of the engines needed for take-off. Such a value is generally known by the name TOGA (Take Off-Go Around). Thus, during a possible nose-down according to the phase of flying horizontally at low speed, the harmful situation in which the maximum-extended flaps are blown on by the airscrews of the engines running at the highest speed is avoided.
In a second embodiment, more dynamic than the previous one, said predetermined high value corresponds to a first threshold less than the thrust TOGA of the engines needed for the aircraft to take off, but, on the other hand, the at least partial retraction of the flaps is subject to the additional condition that a nose-down deflection command greater than a second threshold signifying nose-down is addressed to said elevators. Said first threshold may be at least approximately equal to 60% of the thrust TOGA of the engines needed for take-off, while said second threshold corresponds at least approximately to 60% of the total displacement, in the nose-down direction, of the control column available to the pilot to control said elevators.
In order to avoid unwanted triggerings near to the ground, the method according to the present invention is applied only when the altitude of the aircraft is greater than a third threshold which, for example, is at least approximately equal to 30 meters.
BRIEF DESCRIPTION OF THE DRAWINGS
The figures of the appended drawing clearly show how the invention can be implemented. In these figures, identical references denote similar items.
FIG. 1 is a plan view of an airplane to which the present invention can be applied, the wing flaps being shown in the retracted position.
FIG. 2 is a side view, in horizontal flight and at low speed, of the airplane of FIG. 1 , said flaps being shown diagrammatically in the extended position.
FIGS. 3 and 4 illustrate two variants of embodiment of the method according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
The transport airplane 1 , shown diagrammatically in FIGS. 1 and 2 , has a longitudinal axis X-X and comprises two symmetrical wings 2 , each supporting two engines 3 with airscrews 4 . The trailing edges of the wings 2 are provided with controllable moving high-lift flaps 5 , that can assume a retracted position (see FIG. 1 ) and at least one extended position (see FIG. 2 ). The transition from the retracted position to an extended position is illustrated in FIG. 2 by the double arrow 6 .
In its rear part, the airplane 1 is provided with a vertical tail group 7 supporting, at its top end, a horizontal tail group 8 , tilt-adjustable as is illustrated by the double arrow 9 of FIG. 2 . The trailing edge of the adjustable horizontal tail group 8 comprises elevators 10 , hinged on the latter.
As is diagrammatically illustrated by FIGS. 3 and 4 , the flaps 5 are controlled, for extension and retraction, by at least one flap control computer HLCC, which receives commands from the flap control lever 11 , available to the pilot of the airplane 1 .
In horizontal flight at low speed (see FIG. 2 ), the flaps 5 are extended to enable the wings 2 to impart on the airplane 1 a high lift L. This high lift L, augmented by blowing on the wings 2 and the extended flaps 5 by the wind W generated by the airscrews 4 and aided by the thrust T of the engines, exerts, on the airplane 1 , a nose-down moment relative to the center of gravity CG of the latter. To balance this nose-down moment, it is necessary to deflect the adjustable horizontal tail group 8 to nose-up so that it generates a negative lift D generating an opposing nose-up moment relative to said center of gravity.
In this case, as is illustrated in FIG. 2 , said adjustable horizontal tail group 8 is tilted to nose-up by an angle iH relative to the axis X-X and the elevators 10 are advantageously in aerodynamic extension of said adjustable horizontal tail group 8 . The result is that, on said adjustable horizontal tail group 8 , the local impact is strongly negative.
Therefore, if the pilot orders an abrupt nose-down, by imposing on the elevators 10 a nose-down deflection δqp via the control column 12 available to him (see FIG. 4 ), the local impact on said adjustable horizontal tail group can exceed the stalling effect. Subsequently, at the moment when the pilot wants to level the airplane 1 by imposing on the elevators 10 a nose-up deflection δqc via the control column 12 , the airplane will be incapable of performing the necessary flare.
The two variants of embodiment of the method according to the present invention, illustrated diagrammatically and respectively in FIGS. 3 and 4 , make it possible to avoid this situation. In these FIGS. 3 and 4 , an HLCC computer is shown which is capable of controlling the extension and the retraction of the flaps 5 , the lever 11 for deliberately controlling the flaps 5 via the HLCC computer, a sensor 13 for delivering to the latter a signal FP representative of the fact that the flaps 5 are in the maximum extended position and a radio-altimetric probe 14 sending to the HLCC computer the altitude ZRA of the aircraft 1 .
Furthermore, in the variant of FIG. 3 , the HLCC computer receives, from the HLCC gas levers 15 available to the pilot and controlling the speed of the engines 3 , a TOGA signal, indicating that this speed is the maximum speed. In the variant of FIG. 4 , instead of being linked to the gas levers 15 , the HLCC computer is linked, on the one hand, to an on-board computer 16 , for example an FADEC (Full Authority Digital Engine Control) computer capable of sending it a measurement of the current thrust T and, on the other hand, to the control column 12 transmitting to said HLCC computer at least the nose-down commands δqp that it addresses to the elevators 10 .
The logic systems of the two variants of embodiment of the method of FIGS. 3 and 4 are implemented in the respective HLCC computer and, to this end:
the HLCC computer of FIG. 3 contains an altitude threshold HS, for example at least approximately equal to 30 meters, below which the automatic retractions of the flaps 5 are disabled, in order to avoid movements of the latter not controlled by the pilot close to the ground; and the HLCC computer of FIG. 4 incorporates, in addition to the altitude threshold HS, the threshold FNS for the thrust T exerted by the engines 3 and a nose-down command threshold δqps for the elevators 10 .
The thrust threshold FNS can correspond at least approximately to 60% of the maximum thrust of said engines 3 , while the threshold δqps can correspond at least approximately to 60% of the maximum nose-down travel of the control column 12 .
In the variant of embodiment of FIG. 3 , the HLCC computer controls an at least partial retraction of the flaps 5 , when the following three conditions are satisfied:
the measured altitude ZRA of the airplane 1 is greater than said threshold HS, the flaps 5 are in the maximum extended position, which is indicated by the signal FP, and the gas levers are in the TOGA position.
Thus, in this variant of embodiment, the airplane 1 cannot be in a critical position for which, at the same time, the flaps 5 would be in the maximum extended position and the engines 3 would be exerting their maximum thrust. In effect, thanks to the present invention there then occurs an at least partial retraction of the flaps, such that the value of the nose-up angle iH of the adjustable horizontal tail group 8 can be smaller, which improves the stalling margin of the latter at the time of a flare following a nose-down.
In the variant of embodiment of FIG. 4 , the HLCC computer controls an at least partial retraction of the flaps 5 , when the following four conditions are satisfied:
the measured altitude ZRA of the airplane 1 is greater than said threshold HS, the flaps 5 are in the maximum extended position, the measured thrust T, exerted by the engines 3 , is greater than the threshold FNS, and the nose-down command δpq generated by the control column 12 is greater than the threshold δpqs.
Here, too, the stalling margin of the adjustable horizontal tail group 8 is improved at the time of a flare following a nose-down, starting from a phase of horizontal flight at low speed.
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A method for ensuring the safety of an aircraft flying horizontally at low speed includes an operation in which, when the flaps of the aircraft are disposed in a maximum extended position and are blown on by airscrews, the flaps are at least partially retracted, automatically, based on whether the thrust of the engines is at least equal to a predetermined lift value.
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RELATED APPLICATIONS
This is an application claiming priority from U.S. Provisional Application No. 60/907,622 filed Apr. 11, 2007.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO SEQUENCE LISTING, A TABLE OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX
None.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention is generally directed toward a battery powered implantable bone growth stimulator and more specifically to a threaded screw made of nonconductive material upon which a hermetically sealed battery casing is mounted to provide electrical stimulation for bone growth.
2. Background of the Invention
The present invention is directed toward the electronic stimulation of bone (osteogenesis) through or around an orthopedic bone fixation device with an attached implantable bone growth stimulator. It has long been known that the application of electric currents (electric stimulation) can speed bone growth and healing. The electronic stimulation of bone growth has been used in the treatment of fractures, nonunion of bone and to hasten rates of bone fusion as early as the 1800's. Yasuda, in the 1950's in Japan studied the effect of electricity in the treatment of fractures. E. Fukudain “On the piezoelectric effect of bone”, J Physiol. Soc. Jpn. 12:1158-62, 1957, and Yasuda, J. Kyoto Med. Assoc. 4: 395-406, 1953 and showed that electric signals could enhance fracture healing. Both direct current capacitively coupled electric fields and alternately pulsed electro magnetic fields affect bone cell activity in living bone tissue.
Bone has bioelectrical properties with naturally occurring generated stress potentials. When the bone is stressed, it will carry an electropositive charge on the convex side and an electronegative charge on the concave side. Wolff's Law demonstrates that bone will form new bone in areas of compression and bone will be resorbed in areas of tension. This biological response to stress in bone creates mechanically generated electrical fields or “strain related potentials. Areas of active growth in bones carry an electronegative charge. When a bone fractures, the bone becomes electronegative at the fracture site. On a cellular basis it has been discovered that osteoblasts are activated by electronegative charges. Research on the effects of electrical forces on bone cells in bone formation and healing has demonstrated that bone healing can be hastened and enhanced by electricity. Studies have shown that by implanting an electrical stimulation device and applying an electrical current around the bone, that bone formation is increased around the cathode (negative electrode) and decreased around the anode (positive electrode). Further research of the use of bone growth stimulators has discovered that the optimal current for bone growth with electrical stimulation is believed to be between 5 and 20 micro amperes.
K. S. McLeod and C. T. Rubin in “The effect of low frequency electrical fields on osteogenesis”, J. Bone Joint Surg. 74a:920-929, 1992, used sinusoidal varying fields to stimulate bone remodeling. They found that extremely low frequency sinusoidal electric fields (smaller than 150 Hz) were effective in preventing bone loss and inducing bone formation. They also found strong frequency selectivity in the range of 15-30 Hz. Fitzsimmons et al. in “Frequency dependence of increased cell proliferation”, J Cell Physiol. 139(3):586-91, 1985, also found a frequency specific increase in osteogenic cell proliferation at 14-16 Hz.
U.S. Pat. No. 5,292,252 issued Mar. 8, 1994. discloses a stimulator healing cap powered by an internal small battery. The cap can be reversibly attached to a dental implant, and stimulates bone growth and tissue healing by application of a direct current path or electromagnetic field in the vicinity of bone tissue surrounding the implant, after the implant is surgically inserted.
Another dental device described in U.S. Pat. No. 4,027,392 issued Jun. 7, 1972 discloses an embodiment of a bionic tooth powered by a battery including an AC circuit. The microcircuitry indicated by its FIG. 3 is not shown as being incorporated within the cap.
Another related device is disclosed by in U.S. Pat. No. 5,738,521 issued Apr. 14, 1998 which describes a method for accelerating osteointegration of metal bone implants using AC electrical stimulation, with a preferably symmetrical 20 mu·A rms, 60 KHz alternating current signal powered by a small 1.5 V battery. However, this system is not a compact, self-powered stimulator cap, but is externally wired and powered.
Osteogenetic devices are as described in U.S. Pat. No. 6,605,089 issued Aug. 12, 2003 which discloses a self contained implant having a surgically implantable, renewable power supply and related control circuitry for delivering electrical current directly to an implant which is surgically implanted within the intervertebral space between two adjacent vertebrae. Electrical current is delivered directly to the implant and thus directly to the area in which the promotion of bone growth is desired.
U.S. Pat. No. 6,034,295 issued Mar. 7, 2000 discloses an implantable device with a biocompatible body having at least one interior cavity that communicates through at least one opening with the surrounding body so that tissue surrounding the implantable device can grow through the opening. Two or more electrodes are contained within the device having terminals for supplying a low-frequency electrical alternating voltage and at least one of which is located inside the cavity. U.S. Pat. No. 5,030,236 issued Jul. 9, 1991 also discloses the use of electrical energy that relies upon radio frequency energy coupled inductively into an implanted coil to provide therapeutic energy. However, none of these devices perform satisfactory osteogenesis promotion, while leaving the implant member or stem essentially unchanged in appearance and mechanical properties.
The art that relates specifically to bone growth stimulation by small, self powered electrical means is very limited and most of the bone graft stimulation has been undertaken using power sources located outside the patient's body. Another problem that occurs when the implant is self powered is that the power short circuits against the metal screw or device.
There is thus a widely recognized need for a practical, self-powered osteogenesis implant that can generate electrical stimulation signals. It would also be extremely advantageous that such implants, when used for example in hip or knee implants, should require minimal changes to both appearance and mechanical integrity and function of the implants. The primary goal of such devices would be to increase bone density and implant bone contact ratio around any new implant as a routine common clinical practice.
SUMMARY OF THE INVENTION
According to the present invention there is provided an osteogenesis device including an implant member in the nature of a nonconductive screw having a battery cap mounted thereto to provide electrical signals from the cap to the tip of the screw to function as an electrical bone growth stimulation device. In another embodiment, a universal cap mount with an internal electrical source is mounted on a standard pedicle screw to provide electrical bone growth.
It is still another object of the invention to provide a self container power source and generating circuit in the implant.
It is yet another object of the invention to provide a powered electrical screw implant which does not short out when used for electrical stimulation.
It is another object of the present invention to provide an electrical bone growth promotion implant in which an active cathode is fully contained within the bone fusion mass.
It is a further object of the invention to provide a method of fixation of fractures that not only stabilizes the bone but also enhances bone healing with the use of electricity that can be applied through or around the implant.
It is yet another object of the invention to provide an implant to which a bone growth stimulator can be attached to enhance bone formation at spinal fusion sites.
It is still another object of the invention to provide a self powered implant with a tissue-contacting body having an external surface in contact with biological tissue and having a hollow enclosure, a conductive element in electrical communication with the hollow enclosure and electrically isolated from the external surface, and an electrical stimulation mechanism located within the hollow enclosure for providing electrical stimulation to the biological tissue through the conductive element.
It is yet another object of the present invention to provide an electrical bone growth promotion implant in which the power source can be wholly or partially supplied or recharged by externally applied sources;
It is another object of the invention to provide an implantable bone growth stimulator implant that can be attached to an intramedullary nail or rod to enhance bone formation and healing at fracture or fusion sites.
It is still another object of the invention to provide an implantable bone growth stimulator that can provide a D. C., constant current source.
It is yet a further object of the present invention to provide an implantable bone growth stimulator that can be attached to an orthopedic implant in combination with an internal or external implantable cathode and anode that are sized to enhance bone growth stimulation.
It is another object of the present invention to provide an implantable fixation implant for cooperation with an internal power supply where the fixation implant serves to treat avascular necrosis;
It is still another object of the present invention to provide an implantable bone growth stimulator and orthopedic implant to which a radio frequency identification device can be embedded or attached.
These and other objects, advantages, and novel features of the present invention will become apparent when considered with the teachings contained in the detailed disclosure along with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the inventive electrical bone screw assembly with component cap parts shown in phantom;
FIG. 2 is an exploded view of the bone screw assembly of FIG. 1 ;
FIG. 3 is a perspective view of the electrical bone screw assembly shown in FIG. 1 showing the cap casing stem threadably mounted in the screw head and the cathode mounted in the lumen of the screw shaft;
FIG. 4 is perspective view of the battery cap housing;
FIG. 5 is a perspective view of the cathode mounted in the cap housing stem;
FIG. 6 is the assembled electrical screw assembly;
FIG. 7 is a schematic of the battery casing, current circuit and lead wire;
FIG. 8 is an electrical diagram of the circuit constant current source;
FIG. 9 is a perspective view the driver used to insert the electrical bone screw;
FIG. 10 is an enlarged view of the driver tip of the driver shown in FIG. 9 inserted into the screw head to apply torque to the screw;
FIG. 11 is a perspective view of the bone growth stimulator assembly attached to an internally threaded screw mounted in a bone plate;
FIG. 12 is a perspective view of an external lead which can be mounted on the electrical screw assembly forming a cathode;
FIG. 13 is a perspective view of the external cathode lead shown in FIG. 12 attached to the electrical screw assembly shown in FIG. 11 ;
FIG. 14 is a perspective view of an inventive pedicle screw electrical stimulation device using the cathode lead shown in FIG. 12 mounted to spinal vertebrae;
FIG. 15 is an enlarged view of the pedicle screw electrical stimulation device of FIG. 14 ;
FIG. 16 is a perspective view of the pedicle screw electrical stimulator device of FIG. 15 showing the universal mount and battery casing in phantom;
FIG. 17 is a cross sectional view of the pedicle screw electrical stimulation device of FIG. 15 ;
FIG. 18 is a view of the battery cap of FIG. 15 with elements shown partially in phantom; and
FIG. 19 is a schematic showing the inventive surgical screw used in the hip to treat vascular necrosis.
DETAILED DESCRIPTION OF THE INVENTION
The best mode and preferred embodiment of the present invention is shown in FIGS. 1-8 . The cannulated threaded screw 20 is preferably manufactured out of a non-electrically conductive material such as the non-bioabsorbable polymer PEEK (Polyther-ether-ketone) or other type of hardened material such as ceramic, PSU (polysulphone) or PEKK (Polyether-ketone-ketone) or compositions of the same or any of a wide variety of suitable poly (ether-co-ketone) materials which are commercially available. Because the screw is insulated (nonconductive material or conductive material with nonconductive material to the tip, the current flows around the screw from the insert to the tip of the insert and does not actually flow through the screw which prevents shortage of current which is different from other electrical stimulation devices.
Alternatively, the cannulated threaded screw 20 can be manufactured out of conductive material such as stainless steel, titanium, titanium alloys or other conductive metal or allograft cortical bone with an inner insulated sleeve which is inserted through the screw lumen.
The electrical threaded screw 20 is preferably constructed of non conductive material as previously described with a head 22 defining torque receiving means in the nature of a cutouts 25 which may be four or more in number with a threaded shank 26 extending therefrom. The shank defines a through going lumen 28 which is centrally axially located within the shank and has external threads 30 formed along at least a portion of the shank. The head 22 also defines a chamber 32 at the proximal end of the lumen 28 which is threaded to receive a threaded stem 42 of battery casing 40 as is shown in FIG. 4 . If desired the chamber 32 can be formed to fit a snap casing stem 43 such as that shown in FIG. 2 .
The casing 40 is preferably disc shaped and hermetically sealed. The casing 40 is formed with a housing 41 and a cap 49 which is press mounted over the housing 41 . Mounted in the housing 41 is an integrated circuit board 45 and a battery 44 which is electrically connected to a chip 46 which has a circuit 48 as shown in FIG. 8 . The battery 44 is held in place by battery clip 54 and a sealing ring 56 and sealing top member 58 are held in place by leaf spring 59 when the cap 49 is mounted over housing 41 . The circuit board 45 provides a constant current source via connector member 57 to a cathode lead wire 50 which is encased in a silicon insulating tube 51 . The lead wire and insulating tube 51 are positioned through the lumen 28 of screw shank 26 so that the tip 52 of the cathode extends outside of the shank body. The current which is produced ranges between 5 and 50 micro amperes with the preferred range being between 5 and 20 micro amperes and the most preferred range is 20 micro amperes. Rechargeable lithium batteries are an alternative way to power the bio-implantable microsystem. Power is delivered remotely to charge the implanted battery which eliminates the necessity for battery replacement. Thus the tip 52 acts as a cathode and the casing 40 acts as an anode.
The circuit diagram shown in FIG. 8 shows a representative current of 20 micro amperes which can be modified as desired by changing the resistor 55 in the circuit and the case housing forms the anode for the circuit. An RFID chip can be mounted in the casing 40 allowing easy identification of the implant outside of the patient's body with the additional benefit that it can be used to power the implant. The electrical screw assembly when implanted in the bone and set to generate a current of 20 micro amperes is particularly effective in the treatment of avascular necrosis.
Alternatively the present invention can use a signal conditioning circuit for a remotely rechargeable system. A rechargeable lithium ion battery powers this circuit. The desired output, then goes directly to the electrodes. A second rechargeable lithium ion battery may be included to serve as a back up and in this embodiment a lithium ion charging chip is included which is connected to the designed integrated circuit through a logic interface. The two batteries would work in tandem thus when one battery powers the integrated circuit, the other battery gets recharged and vice versa providing an uninterruptible output. The integrated circuit optionally can use a series of charge pumps or transistors to get the required boost in voltage. This alternate integrated circuit uses voltage detector circuits to detect battery voltages, has a voltage regulator, pulse generator circuits, logic circuits and requisite switches.
The top surface 41 of cap 49 is flat and is provided with an angular cutout 41 ( a ) which allows torque to be generated by an outside tool driving the threaded stem 42 into the screw head chamber 32 so that it is securely mounted to the head of the screw.
As can be seen in FIGS. 9 and 10 a driver 60 is formed with an end 62 having projections 64 which fit in the cutouts 25 of the screw head so that torque can be applied to the screw head driving the screw into the bone of the patient. Once the screw has been implanted into the patient, the battery casing 40 and associated cathode 50 are mounted to the screw 20 by applying torque with a tool mounted in cutout 41 ( a ) and screwing the stem 42 into threaded chamber 32 or pushing the stem 43 as shown in FIG. 2 into a snap on chamber formed in screw head 22 . The device then provides an electrical current through the portion of the patients bone which is fractured or has a defect to promote bone growth.
The electrical screw assembly 20 can be used in connection with a bone plate 70 as shown in FIGS. 11 and 13 . In the usage shown in FIG. 13 an external lead 80 is formed with an electrically conductive washer 82 secured to one and having a spiral section 84 at the distal end. The washer 82 is mounted between the screw 20 and casing 40 as shown in FIG. 13 . The lead wire 84 can have one or more sections insulated to provide variances in the electrical field. The washer 82 is mounted around stem 42 and is positioned between the casing 40 and the top surface of the screw head 22 so that the external spiral lead wire 84 extends past the bone plate 70 allowing a primary electrical field to be formed between the cathode spiral lead wire and the anode of the casing.
The electrical screw assembly 20 can also be used in connection with a pedicle screw electrical stimulation device 90 as seen in FIGS. 14-18 . As seen in FIGS. 14-18 , the device 90 has a flexible support mount 92 which fits over and can be universally attached to any make of pedicle screw 200 seen in FIG. 14 as being screwed into adjacent vertebrae 300 .
The support mount 92 is in the form of a base mount member 93 with a central aperture 94 defined in the top surface which receives the snap lock stem 43 of cap member 40 . The base mount member 93 has an inwardly projecting flexible rim assembly 96 which is cammed outward by the action of the stem 43 which is forced into it and snaps back against the lesser diameter of the stem 43 ( a ) to hold the stem 43 in fixed position within the chamber 99 formed by an insert member 120 . Surrounding the central aperture 94 are a plurality of locking recesses 100 as shown in FIG. 16 , which additionally act as spacers and can selectively receive and hold the lock button 49 of the battery casing 40 as best shown in FIG. 18 so that the battery casing 40 cannot be rotated on the top of the pedicle screw 200 . The side wall 95 of the base mount member 93 extends down over the head of the pedicle screw 200 and is formed with a curved cut away channel 102 and a viewing aperture 104 which allows the support mount to be flexibly mounted over the top of the pedicle screw. The cut away channel 102 is best seen in FIGS. 15 and 16 . The base mount member 93 additionally defines curved cutouts 97 which fit over a support rod 208 as shown in FIG. 14 holding the support rod 208 in place in the pedicle screw transverse bore 202 . A threaded interior insert 120 as seen in FIG. 17 is threaded in the pedestal screw 200 and is used to lock the stem 42 / 43 of battery casing 40 to the pedicle screw 200 . As shown in FIG. 17 , the threaded insert 120 defines a chamber 122 which receives a snap on stem 43 to hold the battery casing 40 in a fixed mounted position. An electrical field is generated between the anode and cathode to accelerate bone growth of the fractured vertebrae. The support mount 92 can also be mounted onto an intramedullary nail, pedicle screw rod, surgical plate, surgical washer or plate rod.
The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. However, the invention should not be construed as limited to the particular embodiments which have been described above. Instead, the embodiments described here should be regarded as illustrative rather than restrictive. Variations and changes may be made by others without departing from the scope of the present invention as defined by the following claims:
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The present invention relates to the electrical stimulation of bone growth utilizing implantable bone fixation devices and implants to which are attached a screw of nonconductive material powered by a battery for the purpose of creating an electrical-magnetic field to promote bone healing and bone formation. The electric magnetic field is directed to the bone around the device through a battery of a rechargeable type and can include a radio frequency identification device. A constant current is generated in a range of 5-20 micro amperes to stimulate bone healing and bone formation.
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FIELD OF THE INVENTION
[0001] The present invention relates to an improved surgical method for gastric bypass for treating obesity.
BACKGROUND OF THE INVENTION
[0002] Obesity is increasing in epidemic proportions world-wide. Even mild degrees of obesity have adverse health effects and are associated with diminished longevity. For this reason aggressive dietary intervention is recommended. Patients with body mass indices exceeding 40 have medically significant obesity in which the risk of serious health consequences is substantial, with concomitant significant reductions in life expectancy. For these patients, sustained weight loss rarely occurs with dietary intervention. For the appropriately selected patients, surgery, (bariatric surgery), is associated with sustained weight loss for seriously obese patients who uniformly fail nonsurgical treatment. Various operations have been proposed for the treatment of obesity, many of which proved to have serious complications precluding their efficacy. A National Institutes of Health Consensus Panel reviewed the indications and types of operations, concluding that the banded gastroplasty and gastric bypass were acceptable operations for treating seriously obese patients. Following weight loss there is a high cure rate for diabetes and sleep apnea, with significant improvement in other complications of obesity such as hypertension and osteoarthritis (Livingston, Amer J Surg , 2002; 292: 60-61).
[0003] Open gastric bypass surgery is a surgical procedure aiming to decrease the size of patient's stomach. It includes transecting the stomach and constructing a pouch from a portion of the stomach as well as connecting the pouch to the intestine (anastomosis) so that the digested food from the pouch moves into the small bowel (Sapala et al., Obes Surg 1998; 8: 253-261). Although, gastric bypass surgery helps patients to lose weight and relieves life-threatening diseases associated with extreme obesity, there are several major post-surgery complications which may require additional treatment. These complications include pouch enlargement, marginal ulceration and staple line separation (dehiscence) (Sapala et al., Obes Surg 1998; 8: 505-516).
[0004] Marginal ulcer (MU) is defined as a gastric ulcer of the jejunal mucosa near the site of a gastrojejunostomy (Dorland's Medical Dictionary 1994). The incidence of marginal ulcers after Roux-en-Y gastric bypass varies between 1% and 16% (MacLean et al., J Am Coll Surg 1997; 185: 1-7; Printen et al, Arch Surg 1980; 115: 525-527). Known factors that contribute to the development of MU are disruption of the gastric reservoir staple line, large gastric pouches, mucosal ischemia, and the presence of foreign bodies such as silk, Marlex™, or Gore-Tex™ (Sapala et al., Obes Surg 1998; 8: 505-516).
[0005] One of the most common causes of MU is the presence of a large gastric pouch (MacLean et aL, J Am Coll Surg 1997; 185: 1-7; Printen et al., Arch Surg 1980; 115: 525-527). In the large gastric bypass pouches (>50 cc), oxynic cell concentration on both sides of the partitioned staple line may lead to MU. The parietal cell mass in the pouch may be large enough in the absence of vagotomy to produce acid-pepsin digestion of the jejunal mucosa. By the contrast, the size of the parietal cell mass below the gastric partition may be reduced, which results in loss of duodenal acidification and secretin stimulation. Unopposed G-cell production of gastrin leads to increased hydrochloric acid secretion by the gastric reservoir parietal cells and subsequent MU (Mason in Major Problems in Clinical Surgery , 1981: 1-60, Ebert P A, ed. Vol. XXVI, Philadelphia: W. B. Saunders).
[0006] In gastric bypass procedures with vagally innervated pouches <50 cc in volume, the critical size of the parietal cell mass necessary to produce MU is not known. Moreover, gastric pouches initially measured at 50 cc may become greatly enlarged over time. Chronic overeating in the presence of an unrestricted elastic fundus can change the original size of the pouch significantly. Therefore, many surgeons prefer to isolate the fundus from the pouch by limiting the pouch to the lesser curvature (MacLean et al., J Am Coll Surg 1997; 185: 1-7; Fox S R et al., Obes Surg 1996; 6: 421-425; Sapala J A et al., Obes Surg 1997; 7: 207-210). Unfortunately, oxynic cell mass is concentrated along the proximal magenstrasse, which explains why MU in lesser-curvature pouches appears to be more common than in greater-curvature pouches (Sapala et al., Surg Gynecol Obstet 1984; 158: 178-180).
[0007] Given the benefits of gastric bypass surgery to morbidly obese patients, there is need in the field for improvement of the procedure in order to minimize complications specified above. The present invention is an improved gastric bypass method that helps to avoid common post-operational complications associated with classic gastric bypass.
SUMMARY OF THE INVENTION
[0008] The present invention relates to an improved method for gastric bypass surgery which aids in reducing the incidence of common side effects associated with other bariatric surgical methods. Briefly, the method comprises incising the abdominal cavity of the patient, mobilizing the gastrocolic omentum from the watershed to the angle of His and incising the left phrenoesophageal ligament to expose the junction of the longitudinal muscle fibers of the esophagus with the serosa of the cardia. Once the junction is identified, a window is opened along the lesser curvature of the stomach through the gastrohepatic ligament just proximal to the coronary vein. The proximal jejunum is then divided and the Roux-en-Y limb of jejunum (Sapala et al., Obes Surg 1998; 8: 505-516) is delivered through an opening in the transverse mesocolon. The proximal end of the stomach is then transected at the junction of the cardia and the fundus. The cardia of the stomach is then used to construct a micropouch. A retrocolic side-to-side Roux-en-Y cardiojejunostomy along greater curvature of the stomach is then performed. The proximal fundus of the cardia is then incorporated into the stoma of the anastomosis which is about 10 mm to about 12 mm in diameter. The gastrotomy and jejunotomy incisions are then closed with interrupted serosal sutures without inverting the staple line at the apex of the micropouch. Fibrin glue (e.g., Hemaseel™) is then applied over the closure. The biliopancreatic limb is then connected to a common conduit consisting of both distal jejunum and the entire ileum. The connection is a stapled anastomosis with a 2.5-cm lumen. The anastomosis is sutured and no glue is applied over the closure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] [0009]FIG. 1 is a schematic diagram of the completed micropouch gastric bypass (Sapala-Wood bypass). MP—micropouch, PA—proximal anastomosis, DP—distal anastomosis, BPL—biliopancreatic limb, Roux Limb—Roux-en-Y limb.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Although efficient in treating obesity and diseases associated with it, the classic gastric bypass procedures often result in several characteristic complications, each of which may require additional treatment. Among these complications is the dilation of the gastric pouch constructed during the bypass procedure. It has been noted that even when a 30 cc gastric pouch was used in the standard Roux-en-Y bypass, as many as one third of the patients developed significant dilation of the micropouch.
[0011] In an attempt to avoid this problem, the surgeons attempted to limit the pouch (micropouch) to the cardia of the stomach because it was found that it is the elastic fundus incorporated into the pouch that primarily dilates after surgery. The use of the cardia in constructing the micropouch has the advantage that it is relatively inelastic and thus it not prone to dilation and it contains no acid producing cells which could give rise to marginal ulceration. Despite the attempts to limit the pouch to cardia, several patients even dilated the micropouch after surgery.
[0012] Upon reexamination, it was determined that a portion of the fundus was hiding under the left pheno-esophageal ligament. Therefore, this ligament must be divided in order to place the staple gun used in constructing the micropouch across the cardia, excluding all fundal tissue from the micropouch.
[0013] The present invention provides a technique by which to exclude the gastric fundus from the micropouch, thereby minimizing or eliminating the complications associated with inclusion of the gastric fundus in the micropouch.
[0014] The method of the present invention allows the identification of the true junction between the esophagus and the stomach and therefore allows the construction of a micropouch which excludes the fundus and as a result is limited to the cardia of the stomach.
[0015] The basic approach to accomplish this goal involves dissecting the left phrenoesophageal ligament off of the cardia of stomach thereby allowing identification of the true junction between the esophagus and the stomach. The identification of this true junction allows construction of a micropouch free of excess fundal tissue.
[0016] In certain embodiment of the present invention, the anastomosis between the micropouch and the intestine is sealed with a fibrin glue (e.g., Hemaseel glue [Hemaecure Corp.]). In earlier methods of gastric bypass surgery, the apex of the micropouch was connected with an inverted staple line. However, in one embodiment of the present invention an inverted staple line is not used (uninverted staple line). The elimination of the inverted staple line and the use of the fibrin glue allow the fast and efficient empting of the esophageal and micropouch contents into the intestine. The example set out below is presented by way of illustration and is not entitled to limit the invention as set out in the appended claims. Certain modifications to the method will be apparent to those of ordinary skill in the art and are encompassed by the appended claims.
EXAMPLE 1
Improved Sapala-Wood Micropouch SM
[0017] In the micropouch gastric bypass operation of the present invention, a midline incision is made from the xiphostemum to the umbilicus. A dissection is carried down through the subcutaneous tissues to the level of the linea alba. A window is then opened in the peritoneum lateral to the midline incision and the abdominal cavity is entered. This allows placement of the self-retaining retractor system which gives access to the left upper quadrangle of the abdomen. The gastrocolic omentum is then taken down from the watershed to the gastroesophageal junction, completely mobilizing the gastric fundus and obliterating the angle of His. Preferably most of this mobilization is accomplished utilizing a harmonic scalpel (Ethicon Corp.).
[0018] On occasion, large short gastric vessels are individually ligated using fine silk sutures. The left phrenoesophageal ligament is then transected enabling the identification of the junction between the esophagus proximally and the serosa of the stomach distally. Ultimately, the stomach will be divided at the cardiofundic junction, 1 to 2 centimeters below the lower esophageal sphincter.
[0019] An incision is then developed through the transverse mesocolon, large enough to accommodate a Roux-en-Y jejunal limb with its associated mesentery (see, e.g., Sapala et al., Obes. Surg ., 1998;8:505-516). This window is 3-4 cm in diameter. The Roux-en-Y limb and biliopancreatic limb are measured at 200 and 150 centimeters, respectively (FIG. 1). This leaves a 200 to 400 centimeter common conduit consisting of both distal jejunum and the entire ileum. The proximal jejunum is then divided preferably with a U.S. Surgical Corp. TLC 55 or similar device (e.g., multifire endo GIA, U.S. Surgical Corp.). The mesentery is then immobilized by dividing two vascular arcades, ensuring an adequate limb length from the proximal anastomosis with the micropouch (FIG. 1). The transected ends of the divided small bowel are connected with sutures of lambert 3-0 silk. This is necessary to avoid either a small bowel obstruction or a leak from a staple line itself.
[0020] The Roux-en-Y limb of jejunum is then delivered through the opening in transverse mesocolon to lie alongside of the micropouch for the greater curvature gastrojejunostomy.
[0021] The proximal stomach is then divided at the cardiofundic junction 1 to 2 centimeters below the cardia junction preferably using a staple gun (ILA 100 mm Stapler, U.S. Surgical Corp.). Care is taken to identify and preserve the nerves along the lesser curvature of the stomach. The proximal limb of jejunum is then attached to the esophagus using a basting suture of 2-0 silk. A second basting suture is used at the apex of the micropouch (FIG. 1).
[0022] Gastrotomy and jejunotomy openings are made to accommodate the jaws of a stapler, preferably a GIA 52-mm stapler (U.S. Surgical Corp.) and a retrocolic side to side Roux-en-Y cardiojejunostomy is made along the greater curvature. The anastomosis has an internal diameter of about 10 mm to about 12 mm. The anastomosis is neither reinforced nor banded. The enterostomy (cardiojejunostomy) incisions are closed by approximating the jejunal serosa to the gastric serosa. Since the stoma opening is small, this closure is done using a single layer of lambert silk sutures. The micropouch is now completed with the esophagus proximal to the micropouch. The jejunum lies to its greater curvature side. The bypassed stomach, or a distal gastric remnant, lies inferiorly (FIG. 1). Constructing the micropouch in this manner prevents inclusion of fundal tissue in the micropouch which may result in dilation of the pouch and avoids inclusion of acid producing cells along the lesser curvature which could lead to marginal ulceration. Following closure of the enterotomy incisions, the anastomosis is reinforced with fibrin glue preferably Heemaseel™ (Hemaecure Corp.). The glue polymerizes in 3 to 7 minutes creating a seal along the suture line. The use of fibrin glue in this part of the procedure prevents leaks from the anastomosis which may result in peritonitis. The seal will be absorbed in 5 to 7 days following surgery. The Roux-en-Y jejunum is then anchored to the transverse mesocolon to prevent an internal hernia which can be lethal.
[0023] The biliopancreatic conduit is then connected to the common conduit using stapled anastomosis with (preferably) a 2.5-cm lumen (FIG. 1). Specifically, the distal side-to-side jejuno-jejunostomy is made with a GIA 52 stapler. Again, the enterotomy incisions are closed in one layer using 3-0 silk sutures. No fibrin flue is applied over the anastomosis. The small bowel is placed in its normal intracolic position and covered with omentum. The linea alba and skin are closed with staples (Sapala et al., Surg Gynecol Obstet 1986; 153: 179-180), and the subcutaneous tissues are drained with a closed Hemovac suction system (Arrow Corp., Norwalk, Conn, USA).
[0024] The references cited herein are hereby incorporated by reference in their entirety.
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The present invention is an improved gastric bypass, a surgical method to treat clinically significant obesity, in which the likelihood of post-surgical complications is reduced.
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FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to sewing machines and, in particular, to a new and useful sewing machine for sewing a material workpiece which comprises a needle holder having a sewing needle which is mounted for both pivotal movement for swinging backwardly and forwardly and for vertical reciprocation, and to a feed dog mechanism therefor.
DESCRIPTION OF THE PRIOR ART
In up-to-date heavy duty sewing machines, the so-called high speed sewing machines, which are medium sized, for example, 3.5 mm long, feed steps can be performed at the maximum speed of the intermittently driven feed dogs which move through a rectangular path in a sequence of motions. This is because with longer feed steps, the drive elements performing swing motions, and their bearings, would be exposed to excessive dynamic stresses and a too rapid wear resulting therefrom, and the entire sewing machine would be thrown into strong vibrations adversely affecting the handling of the work.
In normal cases, intermittently operating feed members execute their feed motion only during a part of the stitch-forming operation. Thus, for example, with a pure drop feed or four motion feed, the feed motion is effected while the needle is in a position outside the work whereas, with a combined drop feed and needle advance, the feed motion is effected while the needle is stuck in the work. If one could succeed in advancing the work in the feed direction as well during the period of time of a stitch-forming operation in which, up to now, the work stands still, the work would be advanced during each stitch-forming operation in two or more short feed steps adding to a single long advance. In such a case, the drive elements of the feed mechanism would perform relatively short stroke motions permitting a high speed operation of the sewing machine.
Sewing machines are known in which the work is moved by intermittently operating feed members during the entire stitch-forming operation. For example, a sewing machine equipped with an upper and a lower feed wheel is known in which, during a single stitch forming operation, each of the feed wheels executes two equal feed steps of which one is effected while the needle is stuck in the work and the other is effected while the needle is in a position outside the work. The desired effect of the immediate succession of the feed steps interrupted only by extremely short standstill periods is that the operator perceives the advance motion of the work as if it were a continuous motion and, therefore, becomes less rapidly fatigued than while checking a much more jerky feed caused by longer standstill periods. This known feed mechanism, however, is not suitable for high speed sewing machines, primarily treating textile fabrics, since in view of such material, disadvantages are connected to machines quite generally equipped with feed wheels. For example, the linear contact between feed wheel and material results in a high surface pressure capable of damaging thin and sensitive fabrics. Another disadvantage is that due to the particular design of the drive mechanism, neither a reversal of the feed direction nor a reduction of the feed steps can be effected during the run of the machine, so that consequently, the stitches can neither be locked nor made more dense in order to secure the end of the seam.
In another known sewing machine, a completely continuous feed is obtained. This, however, is a special sewing machine for the shoemaking industry, comprising a curved hook-type needle rotatably mounted above the work, a presser foot, a curved awl rotatably mounted beneath the work, and a work supporting table. These four parts of the machine execute a rectangular cycle of mutually dephased motions during which one or more of the elements always alternately act on the work and advance it during the entire stitch forming operation, at a constant speed.
As mentioned, this machine is a special device for the shoemaking industry and because of the use of an awl and a hook-type needle, it is basically unsuitable for treating textile fabric. In addition, the drive mechanism of the feed members which comprise cam plates and feeler rolls, long rocking levers and a reciprocating slider, carrying still other component parts, is also entirely unusable for high speed machines because the mentioned parts of the machine would be stressed beyond their rupture limits by the extremely high dynamic forces occurring at high speeds. Another drawback of this shoe sewing machine is that, for changing the feed advance, or the stitch length, during the standstill of the machine, no less than three rocking levers must be adjusted as to their effective lever length. Moreover, care must be taken that the lever lengths are adjusted exactly uniformly; since otherwise, either the awl or the needle would break, or the work would be damaged by the feed members executing irregular motions. Because of the complicated and time-consuming adjustment of the feed rate, this shoe sewing machine neither permits a locking of the seams nor a shortening of the stitch length and this is a further reason why this feed mechanism is absolutely unsuitable for high speed sewing machines for working textile fabrics.
SUMMARY OF THE INVENTION
The present invention permits the joining of textile fabric by long-stitch seams in sewing machines running at high speeds and, if desired, of securing the seams by locking the seam ends or condensing the stitches. For this purpose, the invention is directed to a feed mechanism comprising feed members acting on the work alternately during the entire stitch-forming operation and being adjustable, as to the direction and amount of their motion, by means of a common adjusting device.
In accordance with the invention, two feed dogs are provided, operating in a rectangular sequence of motions, in which one feed dog is positioned in the area of the motion path of the needle and its cycle of motion is adjusted to the advance motion of the needle, while the other feed dog is positioned in advance of the first feed dog in respect to the feed direction, and its cycle of motion is in phase opposition relative to the cycle of motion of the first feed dog.
During each stitch forming operation, the inventive feed mechanism advances the work by two feed steps in which the first step is executed conjointly by the first feed dog and the needle stuck in the work, while the second step is executed by the second feed dog, and during a period of time in which the needle is in a position outside the work, the first feed dog executes a rearwardly directed motion. If the new feed mechanism is used in a high speed sewing machine designed for a maximum permissible feed rate of the drive elements of, for example, 3.5 mm at the maximum speed, a total advance of the work of 7 mm is obtained at this maximum speed, which is extremely high as compared to normal high speed sewing machines. With normal stitch lengths, the two feed dogs execute short-stroke motions such that even at the maximum speed, a particularly smooth run of the drive elements of the feed mechanism is obtained. The smoothness of run is favored, in addition, by the fact that the motions of the feed dogs are in respective opposite directions whereby any dynamic forces which might have occurred are mutually compensated.
The drive mechanism for the two feed dogs may be designed in a manner similar to the known sewing machines equipped with a differential bottom feed and also provided with two feed dogs mounted one behind the other, however, with such a design, in the present case, the eccentrics for producing the respective rectangular motions must be adjusted in mutually dephased positions. Also, as in the known machines, the feed rates of the two feed dogs can be conjointly adjusted by means of a single stitch guide so that, for locking the seam or condensing the stitch, the feed direction can be reversed or the rate of the advance motion can be reduced.
Although the second feed step in each stitch forming operation is performed by only one feed member, namely the second feed dog, no disalignment occurs during the advance of two or more superposed fabric layers. That is, since the second dog is positioned in advance of the path of motion of the needle and, thereby, ahead of the stitch forming area of the sewing machine, it engages the work at a location where the fabric layers are already joined to each other by the previously formed stitches so that a mutual displacement of the fabric layers is not possible.
Due to the motion in phase opposition, thus with an angle of phase difference of the two feed dogs of substantially 180°, aside from the particularly uniform motion conditions, a further advantage is obtained in that, at the instant the take-up lever of the thread passes its top dead center, the second dog still accomplishes its advance motion. Thereby, an additional tensile force is exerted on the last-formed stitch which has already been tightened by the take-up lever, so that the thread in the stitch is definitely fastened. Also, in this case, the tensile force exerted by the take-up lever on the thread need not be so strong as if the lever acted alone. Consequently, the operation can be performed with a reduced needle thread tension whereby the thread is stressed less.
Accordingly, it is an object of the invention to provide an improved sewing machine for sewing material workpieces, which comprises a needle holder having a sewing needle which is mounted for swinging as well as reciprocal movement and which is operated in timed relationship to a pair of feed dogs which are moved alternately in opposite phase relationship and with one being engageable with the material during the penetration of the material by the needle and movable with the needle in the advance direction of feed during the time in which the other moves out of engagement with the material and to a return position for immediate engagement with the material as the first dog disengages the material.
A further object of the invention is to provide a sewing machine construction in which there is a simple control for varying the amplitude and direction of motion of two out of phase movement feed dogs in response to the reciprocation and swinging movement of a needle.
A further object of the invention is to provide a sewing machine and feeding mechanism therefor which are simple in design, rugged in construction and economical to manufacture.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the Drawings:
FIG. 1 is a perspective view of the feed mechanism of a sewing machine, also showing the drive means, constructed in accordance with the invention;
FIG. 2 is a simplified elevational view of the sewing machine in which the feed members are diagrammatically shown in their position at the beginning of the first feed step during a stitch forming operation;
FIG. 3 is a schematic front elevational view of the instantaneous positions of the feed members at the beginning of the second feed step; and
FIG. 4 is a schematic front elevational view of the instantaneous positions of the feed members at the end of the second feed step.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in particular, the invention embodied therein, comprises a sewing machine, generally designated 90, which, as is visible in FIG. 2, includes a bed plate 1 over which a material 73 to be worked upon is advanced along a sewing machine frame or support 2. Sewing machine frame 2 includes a head portion or casing 3 and a main shaft 4 is mounted within the casing for driving a needle bar 7 for both vertical reciprocation and swinging movement. The vertical reciproation of needle bar 7 is effected through a crank drive mechanism, including a crank 5 and a link 6. Needle bar 7 is also mounted for oscillation along with an oscillating arm 9 upon which it is mounted which swings about a pivot 8. Needle bar 7 carries a thread-guiding needle 10. A presser foot 12, as shown in FIG. 1, is secured to a presser bar 11.
In accordance with the invention, the sewing machine includes a feeding mechanism in the form of first and second feed dogs 31 and 34 which alternately and cyclically engage the workpiece 73 and advance it in the feed direction indicated by the arrow V. The first feed dog 31 engages the material 73 during a time at which the needle bar 7 and needle 10 are swung in the direction of the arrow 92. This is also effected during a time at which the needle 10 is moved downwardly in the direction of the arrow 94 to engage into material 73. During the advance movement of the feed dog 31 in the direction of the arrow 96, the second feed dog 34, which is out of phase with the first feed dog 31, moves out of engagement with material 73 in a return direction, in the direction of the arrow 98.
In accordance with the invention, the sewing machine comprises a mechanism, generally designated 13, for adjusting the swinging motion of the oscillating arm 9. The oscillating arm adjusting mechanism 13 includes an adjusting shaft 14 to which a bracket 15 is secured. Between arms 15a and 15b of bracket 15, a further bracket 16 is mounted for rotation by means of pins 17 and 17a. Arms 16a and 16b of bracket 16 are connected to each other by a pin 18 to which swinging motion about pins 17, 17a is imparted by an eccentric 19 secured to main shaft 4, through an eccentric arm 20. Pin 18 further carries a link 21 which is pivoted by means of a pin 22 to a crank 23 which is secured to one end of an oscillating shaft 24 extending in parallel to main shaft 4. The other end of oscillating shaft 24 is connected to a crank 25 carrying a pin 26 which is guided between two flanges 27 provided on the back side of oscillating arm 9.
In bed plate 1, two coaxial shafts 28 and 29 extending parallel to main shaft 4 are mounted, the inner shaft 28 projecting at both ends beyond the outer shaft 29. A clevis 30 is secured to inner shaft 28 and a feed dog bar 32 carrying a first feed dog 31 is pivoted on the clevis. To outer shaft 29, clevis 33 is secured, to which a feed dog bar 35 carrying the second feed dog 34 is pivoted. Each of the feed dog bars 32, 35 has a forked end portion 32a, 35a, respectively, receiving a lifting eccentric 37, 38 secured to a shaft 36. At the rotation of shaft 36, eccentrics 37, 38 impart the lifting motions necessary for producing the rectangular motion cycle to feed dogs 31, 34. As may be seen in the drawing, the two eccentrics 37, 38 are mounted in phase opposition, wherefore, the vertical motions of the two feed dog bars 32, 35 and, consequently, of the two feed dogs 31, 34, are opposite to each other.
A feed dog control mechanism for producing and adjusting the horizontal advance motions of the two feed dogs 31, 34 is generally designated 39. A shaft 40 which is parallel to shafts 28, 29, is mounted in bed plate 1 and receives its motion from main shaft 4, through a drive belt (not shown). Two push eccentrics 41, 42 are secured to shaft 40, each of which is embraced by an eccentric arm 43, 44, respectively. As shown in the drawing, the two push eccentrics 41, 42 are also mounted in phase opposition so that the two eccentric arms 43, 44 execute opposite motions.
Two links 54 and 55 are pivoted to eccentric arm 44 by means of a pin 53. Link 54 is rotatably connected, by means of a pin 56, to a crank 57 which is secured to an adjusting shaft 58. By means of a pin 59, link 55 is pivoted to a crank 60 which is secured to the inner shaft 28. Cranks 49, 57 and 52, 60, as well as links 46, 47 and 54, 55 have the same effective lengths.
Two links 46 and 47 are pivoted to eccentric arm 43 by means of a pin 45. Link 46 is rotatably connected, by means of a pin 48, to a crank 49 which is secured to an adjusting shaft 50. Link 47 is pivoted, by means of a pin 51, to a crank 52 which is secured to the outer shaft 29.
A three-arm feed dog and needle swing adjustment crank 61 for a simultaneous adjustment of all of the three adjusting shafts 14, 50 and 58, is secured to adjusting shaft 50. Crank 61 has one arm 61a connected, through a link 62, to a crank 63 which is secured to adjusting shaft 58 while another arm 61b of crank 61 is connected, through a link 64, to a crank 65 which is secured to adjusting shaft 14. Against a third arm 61c of crank 61, a link 67 is applied through a ball-and-socket joint 66 which, through a further ball-and-socket joint 68, is operatively connected to a two-armed lever 69. The other arm of lever 69, which is secured to a shaft 70 mounted in support 2, engages into a groove 71a of an adjusting disc 71 which is also rotatably mounted on support 2. A tension spring 72 applies against arm 61c at its one end and, at its other end, it is attached to the casing of the sewing machine. The end portion of lever 69 engaging groove 71a is biased by spring 72 against the exterior wall of groove 71a, and the feed dogs 31, 34, in connection with needle 10, feed the work 73 in the advance direction. For reversing the feed direction, a switch lever 74 is secured to the end of shaft 70 projecting from support 2, by which lever 69 can be pivoted so as to apply against the interior wall of groove 71a.
The feed mechanism operates as follows:
In FIG. 1, adjusting disc 71 is adjusted to the stitch length zero. In this position, the axes of pins 48, 51, of pins 56, 59, and of pins 17, 17a, 22 are aligned so that links 47, 55 and 21 execute pure rotary motions about the respective pins 51, 59 and 22 while cranks 52, 60 and 23 stand still. Since, consequently, shafts 28, 29 and oscillating shaft 24 also stand still, feed dogs 31, 34 and needle 10 do not execute any feed motion.
For adjusting a feed rate, as soon as adjusting disc 71 is turned out of its zero position, adjusting shaft 50 is turned also through lever 69, link 67 and three-arm crank 61. While turning, adjusting shaft 50 takes crank 49 along, thereby displacing pin 48 serving as axis of rotation for link 46 off alignment with pin 51 which serves as axis of rotation for link 47. In consequence, during the pivotal motion of pin 45 caused by eccentric arm 43, link 46 executes a pure rotary motion about pin 48 while link 47, aside from a rotary motion about pin 51, executes a relative motion about shaft 29 in addition. This relative motion is transmitted by crank 52 as a pivotal motion to clevis 33 which, through feed dog bar 35, imparts advance motions to second feed dog 34.
The turning of adjusting shaft 50 has the effect that, through crank arm 61a, link 62 and crank 63, adjusting shaft 58 is simultaneously turned through the same angle. Due to this motion, link 54 is pivoted by crank 57 which is secured to shaft 58, so that pin 56 is displaced off alignment with pin 59. Consequently, during the pivotal motion of pin 53 caused by eccentric arm 44, link 54 executes a pure rotary motion about pin 56 while link 55, in the same manner as mentioned above in connection with link 47, aside from a rotary motion about pin 59, executes a relative motion about shaft 28, in addition. This relative motion is transmitted, by crank 60, as a pivotal motion to clevis 30 which, through feed dog bar 32, imparts advance motions to first feed dog 31 which are exactly equal to the advance motions of second feed dog 34. In addition, the turning of adjusting shaft 50 has the effect that, through crank arm 61b, link 64 and crank 65, adjusting shaft 14 is simultaneously turned through the same angle. During this motion, bracket 16 is pivoted by bracket 15 which is secured to shaft 14, so that pins 17, 17a serving as axis of rotation for bracket 16 are displaced off alignment with pin 22. Consequently, during the pivotal motion of pin 18 caused by eccentric arm 20, bracket 16 executes a pure rotary motion about pins 17, 17a while link 21, analogously to links 47 and 55, in addition to a rotary motion about pin 22, executes a relative motion about oscillating shaft 24. This oscillating motion is transmitted, through crank 25 and pin 26, to oscillating arm 9 which, in consequence, executes oscillating motions in the feed direction about pivot 8.
As already mentioned, both the lifting eccentrics 37, 38 and the push eccentrics 41, 42 are mounted in phase opposition so that the two feed dogs 31, 34 execute mutually opposite motions in the vertical and horizontal directions. These motions are adjusted to the oscillatory motion of needle 10 in a manner such that during a stitch-forming operation, the first feed dog 31 along with needle 10 executes a first feed step and, subsequently, the second feed dog 34 executes a second feed step. The instantaneous positions and motion directions of these three feed members (10, 31, 34) in different phases of a stitch-forming operation are diagrammatically shown in FIGS. 2 to 4 with the aid of direction arrows.
FIG. 2 shows the instantaneous motion conditions at the beginning of the first feed step. The needle 10 stuck into the workpiece 73 and the first feed dog 31 applying from below against the workpiece 73, move in the feed direction V while the lowered second feed dog 34 executes a rearwardly directed motion. FIG. 3 shows the instantaneous motion conditions at the beginning of the second feed step. At this instant, second feed dog 34 is lifted and executes a feed motion alone, while needle 10 is in a position outside the workpiece 73 and moves upwardly and executes, along with the lowered first feed dog 31, a rearwardly directed motion opposite to the feed direction V. FIG. 4 shows the instantaneous motion conditions at the end of the second feed step. The second feed dog 34 having reached the end point of its advance motion is going to be lowered while the first feed dog 31 having reached the end point of its return motion is going to be lifted. At the same time, needle 10 approaches the workpiece 73 again.
In this manner, workpiece 73 is advanced by two feed steps during each stitch forming operation, which steps add to a large total advance resulting in a long stitch. Since, at the same time, feed members 10, 31, 34 travel along relatively short distances, the sewing machine can run at the maximum speed, for example, at 6,000 rpm of main shaft 4, and produce seams having 7 mm long stitches. For securing the thread at the end of the seam, the feed direction of the feed members 10, 31, 34 can be reversed during the run of the sewing machine by actuating switch lever 74.
Due to the phase opposition between lifting eccentrics 37, 38 and push eccentrics 41, 42, the drive elements actuated by these eccentrics and, at the end of the train, also the two feed dogs 31, 34, execute mutually opposite motions. As a result of these motion conditions, the dynamic forces produced by the oscillating drive elements and the feed dogs 31, 34 act against one another, thus are mutually compensated and, with substantially no vibrations, the run of the sewing machine becomes particularly smooth.
Further, again due to the operation in phase opposition of the two feed dogs 31, 34, a motional sequence is obtained in that the second feed dog 34 still accomplishes the last part of its advance motion while the take-up lever 75 for the thread has already passed its top dead center. In this way, the second feed dog 34 exerts an additional tensile force on the last formed stitch which has been lever by the take-up lover 75, whereby, the thread in this stitch is definitely fastened. In consequence, take-up lever 75 does not need to exert as strong a tensile force on the thread as it would if it was necessary for it to tighten the thread alone, and the operation can be effected with a reduced tension of the needle thread and, therefore, with a thread which is stressed less.
The inventive idea underlying the described embodiment can be applied in the same effective manner as well to a sewing machine which, in addition to the feed mechanism disclosed, comprises a top feed dog. In such a case, the first feed step in each stitch forming operation would be performed by the first feed dog along with the needle and the top feed dog, while the second feed step, as before, would be performed by the second feed dog alone.
While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
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A sewing machine for sewing a material workpiece, comprises a needle holder having a sewing needle which is mounted for both pivotal movement for swinging backwardly and forwardly and vertical reciprocation. The needle is driven by a sewing machine main shaft which also drives first and second feed dogs which are independently cyclically and alternatively engageable with the material to be sewn for advancing it in timed relationship to the reciprocation and to the swinging movement of the needle.
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BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for controlling supplemental heat in a heat pump, wherein a controllable heating element is used in combination with the indoor fan coil to heat the supply air, and is controlled primarily based on the temperature of the air leaving the indoor fan coil, substantially independent of the temperature sensed at the indoor thermostat. The temperature of the air leaving the indoor fan coil can be sensed directly or predicted based on the sensed outside ambient air temperature.
Heat pump systems use a refrigerant to carry thermal energy between a relatively hotter side of a circulation loop, where compression of the refrigerant by a compressor raises the temperature of the refrigerant, to a relatively cooler side of the loop at which the refrigerant is allowed to expand, causing a temperature drop. Thermal energy is added to the refrigerant on one side of the loop and extracted from the refrigerant on the other side, due to the temperature differences between the refrigerant and the indoor and outdoor air, respectively, to make use of the outdoor air as a thermal energy source.
Heat pumps used in residential heating and cooling are bidirectional, in that suitable valve and control arrangements selectively direct the refrigerant through indoor and outdoor heat exchangers so that the indoor heat exchanger is on the hot side of the refrigerant circulation loop for heating and on the cool side for cooling. A circulation fan passes indoor air over the indoor heat exchanger and through ducts leading to the indoor space. Return ducts extract air from the indoor space and bring the air back to the indoor heat exchanger. A fan likewise passes ambient air over the outdoor heat exchanger, and releases heat into the open air, or extracts available heat therefrom.
These types of heat pump systems can operate only if there is an adequate temperature difference between the refrigerant and the air at the respective heat exchanger to maintain a transfer of thermal energy. For heating, the heat pump system is efficient provided the temperature difference between the air and the refrigerant is such that the available thermal energy is greater than the electrical energy needed to operate the compressor and the respective fans. The temperature difference generally is sufficient for efficient cooling, even on hot days. However, for heating when the outdoor air temperature is below about 25° F., the heat pump system may be unable to extract sufficient heat from the outdoor air to offset the loss of heat from the space due to convection, conduction and radiation of heat from the structure to the outdoors.
When the heat pump is unable to provide enough heat to the structure (i.e., the outdoor temperature is below the balance point between the building load and the heat pump capacity) a supplemental heating element is provided in the supply air duct downstream from the indoor heat exchanger/coil to supply the additional heat required to maintain the desired indoor air temperature. Activation of the supplemental heating is typically controlled by an indoor thermostat, by which the occupants set a desired temperature to be maintained in the space by operation of the heating system.
Conventional heat pump control systems use a two-stage-heat/one-stage-cool room thermostat. On a first call for heat from the thermostat, the heat pump compressor and fans are activated to extract heat outdoors and to release the heat indoors. The heat pump supplies air to the structure (typically at about 80° F.) until the indoor temperature reaches the thermostat set point (i.e., the first set point) and then is deactivated. If the heat loss of the structure is greater than the capacity of the heat pump, which occurs when the outdoor temperature drops, the indoor air temperature cannot be raised by the heat pump to the desired temperature. The indoor temperature thus continues to drop.
The room thermostat has a second switching means that is operated at a temperature slightly lower than the desired temperature at which the first switching means is operated. Conventionally, when the room temperature falls to the second set point defined by the thermostat, power is supplied to the supplemental heating element. The supplemental heating element supplies the additional heat needed to bring the indoor temperature up to the second set point temperature (typically the supply air is about 125° F.), and thereafter the heat pump works alone to supply heat to the structure until the first set point temperature is reached.
As explained in U.S. Pat. No. 5,367,601, however, conventional two stage heat controls cause wide swings in the temperature of the supply air emitted into the structure by the heat pump system. Such wide temperature swings (e.g., 80° F. to 125° F.) are uncomfortable for the occupants and adversely affect the efficiency of the heat pump system. In an attempt to improve occupant comfort, the '601 patent proposes a control system that provides a closer control on the operation of the supplemental heating, by sensing the supply air temperature and then continuously controlling the on/off condition of the supplemental heating. While this proposal makes strides toward maintaining the supply air temperature at a given level, it has at least two significant drawbacks.
First, the supplemental heating is used only when there has been a second call for heat from the indoor thermostat. This makes it more difficult to maintain the air supply temperature at a constant, predetermined level, as supplemental heating is never energized during first stage heating.
Secondly, the temperature sensor must be positioned in the air supply duct of the building duct work by the technician installing the heat pump. Variations in the position of the sensor can lead to variations in temperature sensing accuracy, which in turn can lead to erroneous control of the supplemental heating by the controller.
U.S. Pat. No. 4,141,408 also discloses control means for controlling supplemental heating elements in a heat pump system. This patent proposes to use sensors positioned on the indoor coil to measure the temperature of the air leaving the coil. The sensors are connected to relays that close to operate one or two fixed output heating elements. This system is unable to prevent wide swings in the air supply temperature, because there is no means for operating the supplemental heating elements during first stage heating. There is also no means for precisely controlling operation of the heating elements, in that they are simply turned on and off in response to the temperatures sensed by the sensors.
U.S. Pat. No. 5,332,028 also discloses a heat pump system having supplemental heat for application to the supply air during periods of defrost operation in order to avoid a "cold blow" condition while the heat pump is operating in the defrost mode. This patent proposes to turn on a supplemental heating element in response to the sensed temperature of the supply air during defrost and responsively turn on additional heat in stages when necessary to maintain the temperature level of the supply air at a comfortable level during defrost. This system, however, also requires the installation technician to position the air supply temperature sensor and thus suffers from the same drawback as discussed above. And there is no means by which the supplemental heating elements are controlled precisely in order to avoid the wide air supply temperature swings mentioned above. Moreover, the supplemental heating elements are not operated during first stage heating in order to insure a constant air supply temperature at all times.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to maintain the temperature of the supply air emitted from a heat pump system at a substantially constant level by providing for precise control of the supplemental heating elements, while removing the possibility of installation error with respect to the location of the temperature sensor downstream of the indoor coil.
The present invention provides a method and apparatus for maintaining a substantially constant supply air temperature in a heat pump system by providing precise control of the supplemental heat supplied to the air stream passing from an indoor coil to an air supply duct of the heat pump system. The heat pump system is of the type that includes an indoor thermostat having a first set point for initiating heat supplied by the indoor coil and a second set point for initiating additional heat supplied by supplemental heating elements. The method includes the steps of providing an adjustable output heating element downstream of the indoor fan coil for heating air passing from the indoor coil to the air supply duct. A microprocessor-based controller senses one of the outdoor air temperature and the coil discharge temperature of the air stream heated by the indoor coil at a position between the indoor coil and the adjustable output heating element, and then selectively energizes the adjustable output heating element in response to the sensed temperature, independent of the second set point of the indoor thermostat. If the adjustable output heating element alone cannot assist the indoor coil in maintaining the air supply temperature at a predetermined base temperature, then one or more fixed output heating elements can also be used.
The present invention is prefaced on the recognition by the inventors that, in order to maintain an air supply temperature at a predetermined base temperature of, say 105° F., it may sometimes become necessary to add supplemental heat to the supply air when the heat pump system is operating only in the first stage (i.e., in response to the first call from the indoor thermostat). The inventors also recognized that the use of fixed output heating elements, even if used during the first stage of heat pump activity, often times supply too much heat to the supply air, thus causing the wide temperature swing problem experienced by prior systems.
The invention overcomes this problem by using an adjustable output heating element in combination with the indoor coil during the first stage of heat pump operation. The adjustable output heating element is powered independent of the second set point of the indoor thermostat, in that there need not be a call for supplemental heat from the thermostat before the adjustable output heating element is energized. In this way, the adjustable output heating element can be powered along with the first stage heating supplied by the indoor coil in order to maintain the supply air at a substantially constant, predetermined base temperature (e.g., 105° F.). If the demand on the adjustable output heating element exceeds its output capability, then the fixed output heating elements also can be energized one at a time in order to meet the building load. And, if the load causes the thermostat to call for supplemental heat, operation of the adjustable output heating element can be disengaged if necessary so that full power can be supplied to as many supplemental heating elements (including the adjustable output heating element) as necessary to satisfy the second call from the thermostat.
The present invention also overcomes the sensor positioning problems discussed above, by using a factory-installed sensor located at the downstream side of the indoor air coil, or alternatively, using an outdoor sensor. In either case, there is no calibration error introduced into the system because there is no need for the installer to position the sensor at a precise location in the air supply duct work of the building to be heated.
These and other objects of the present invention will be better understood by reading the following detailed description in combination with the attached drawings of a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial representation of an indoor coil section of a heat pump system having the present invention incorporated therein;
FIG. 2 is a perspective view of the electric heating module portion of a heat pump system having the present invention incorporated therein; and
FIG. 3 is a graph showing heat pump capacity and building load requirements with respect to outdoor temperature and supply air temperature.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, the invention is shown generally at 10 as incorporated into an indoor coil section 11 having a return air plenum 12, a supply air plenum 13 and a blower motor assembly 14 for drawing the air into the return air plenum 12 and supplying it back to the space to be conditioned by way of the supply air plenum 13. An indoor coil 16 is disposed within the system and has refrigerant circulated therethrough for the purpose of cooling or heating the air passing over the coil 16 as it is circulated through the system. The indoor coil 16 acts as an evaporator in the cooling mode to remove heat from the indoor air and as a condenser in the heating mode to provide heat to the indoor air. During the defrost mode, the system switches from the heating mode to a cooling mode to allow the heat from the indoor air to be transferred by the refrigerant to the outdoor coil to facilitate the defrosting thereof.
An electric heating module 17 is provided just downstream of the blower motor assembly 14. Conventionally the electric resistance heating elements in module 17 are energized to supplement the heat pump during low (e.g., less than 32° F.) outdoor temperature conditions. This module is also used during the defrost mode to heat the air being supplied to the conditioned space while heat is removed from the return air for the purpose of defrosting the outdoor coil. In accordance with the present invention, this module is also operated during the first stage of heat pump operation (i.e., when the indoor coil is usually acting alone to provide the heated supply air). This aspect of the invention will be explained later below in more detail.
A microprocessor-based controller 18 is provided to control the entire heat pump system in response to signals received from an indoor thermostat (not shown) and a temperature sensor 19, such as a thermistor or the like. Thermistor 19 functions to sense the temperature of the air leaving the indoor coil. Thermistor 19 can also be used to sense the temperature of the outdoor air, and in both cases those temperature signals are provided to the controller 18 by way of leads 21 during operation of the heat pump.
The indoor coil 16 is connected to a standard closed loop refrigeration circuit which includes a compressor 22, a 4-way valve 23, an outdoor coil 24 with a fan 26 and expansion valves 27 and 28. The 4-way valve 23 is selectively operated by the controller 18 to function in the respective cooling, heating, or defrost modes, with either the expansion valve 28 functioning to meter the flow to the indoor coil 16 or the expansion valve 27 functioning to meter the refrigerant flow to the outdoor coil 24. The controller 18 can be applied to selectively operate the compressor 22 and the fan 26 as well.
The electric heating module 17 is shown in greater detail in FIG. 2 to include a plurality of electric resistance heating elements 29 which are connected to a pair of power leads 31 by way of a relay (not shown) controlled by controller 18. The heating elements 29 extend rearwardly into the supply air plenum 13 and are vertically supported by a plurality of support rods 32 as shown. Each of the heating elements is preferably rated at 5 kW, although other rated elements can also be used. One of the heating elements is adjustable, in increments as low as 100 W, from 0 up to 5 kW. The remaining elements, preferably up to three additional elements, are all fixed, preferably at the same output rating level. FIG. 2 depicts only a two-element setup.
FIG. 3 shows a graph of outdoor temperature versus air supply temperature, and includes plot HPC showing the heat pump capacity (determined by the parameters of the heat pump system itself) and plot BL showing the building heating requirements (building load). FIG. 3 shows that heat pump capacity decreases and the building load increases, both substantially linearly, as the outdoor temperature decreases. The balance point is where the two lines cross. Conventionally, the first stage of a heat pump system is typically employed to serve the needs of the load at outdoor temperatures above the balance point, whereas second stage heating (supplemental heating) is added to the air supply of the system at outdoor temperatures below the balance point. The balance point for the system depicted graphically in FIG. 3 is about 34° F.
In order to maintain a base air supply temperature of, say 105° F. (the horizontal BT line in FIG. 3), the present invention selectively controls the power supplied to the adjustable output heating element based on the following formula:
kW=Constant×CFM×(T2-T1)
where T2 is the target base temperature (BT) of the supply air,
T1 is the temperature of the air leaving the indoor coil, and
CFM is the airflow through the system (which is known with some fan models and approximated with other fan models).
(The Constant simply assures reconciliation among the various units.) When T1 is sensed at the output of the indoor coil, that reading is used directly in the above formula. However, when sensing the outdoor temperature, T1 is predicted by extrapolation from the graph shown in FIG. 3. This can be done entirely within the controller 18 using well-known look up techniques.
In accordance with the invention and with reference to FIG. 3, the controller periodically calls upon sensor 19 for a temperature reading (T1). The controller then calculates the amount of kW power that must be supplied by the adjustable output heating element. If there has been a call from the indoor thermostat for first stage heat, but T1 equals T2, the system will cycle the first stage heat only, as depicted by the HP ONLY section of the graph in FIG. 3. If, however, T1 is less than T2, the controller will calculate the amount of power to be supplied to the adjustable output heating element using the above formula, and then control the power supplied to the adjustable output heating element using a solid state relay.
The preferred method of supplying power to the adjustable output heating element will now be explained by way of example. Say the calculated power requirement for the adjustable output heating element is 2 kW and the full power rating of the adjustable output heating element is 5 kW. This means that 40% of the full power of the adjustable output heating element is required to raise T1to the base temperature, T2 (BT). Power is supplied to the adjustable output heating element over a fixed number of line cycles, say 100 line cycles for example. If the calculation determines that 40% power is required for the adjustable output heating element, then power will be switched on to that element for 40 line cycles and then switched off for 60 line cycles. This produces the necessary 2 kW output from the adjustable output heating element. This cyclical application of power to the adjustable heating element is repeated continuously for as long as the controller senses (via sensor 19) that T1is less than T2.
Preferably, the power to the adjustable output heating element is changed incrementally, say in increments as low as 2% full power, in order to allow precise control of the air supply temperature. Accordingly, if 40% power is called for the first time T1is sensed, but T1has decreased at the next reading cycle and the controller now calculates that 45% power (i.e., 2.25 kW) is needed to raise T1to T2, then the power to the adjustable output heating element is increased by 5% (i.e., continuously turned on and off for 45 and 55 line cycles, respectively) until T1equals T2. Although increments of 2% can be realized using the present invention, increments of 5% fall power are probably as low as would be needed to deal with fluctuations in T1.
If the calculated power exceeds the rated output of the adjustable output heating element (e.g., 5 kW), then one of the additional fixed output heating elements (e.g., 5 kW each) will be energized by the controller and then the power to the adjustable output heating element will be changed continuously to meet the power demand in excess of 5 kW.
The adjustable output heating element preferably is switched on and off by a solid state relay while the remaining elements are switched on and off using electromechanical relays. The solid state relay is driven by a relay driver circuit incorporated in controller 18. The solid state relay has zero crossing circuitry which switches the adjustable output heating element on and off only when the line cycle crosses zero volts. Thus, the on/off delay of one-half line cycle limits the smallest on time for the heating element to 2 line cycles. In the case of a heating element rated at 5 kW and operating on a 100 line cycle time base, the lowest power output would therefore be 100 W.
The partial lines F1, F2 and F3 in FIG. 3 that parallel the heat pump capacity line show the effect of energizing fixed 5 kW heating elements. The triangular shaded region R1 shows the added capacity as a result of powering the adjustable output heating element as described above. The triangular shaded region R2 shows the added capacity as a result of powering the adjustable output heating element while a first additional fixed 5 kW heating element is energized by the controller. These regions R1 and R2 are bounded by the BT temperature line (105° F. in FIG. 3). The intersection of the BT line with the BL and HPC lines dictates the outdoor temperature range in which the adjustable output heating element (region R1) and, if necessary, one of the additional fixed output heating elements (region R2) are energized cyclically with the first stage heating supplied by the indoor coil. To the left of the intersection of the BT line with the BL line, the heat pump capacity is so low that the system runs the indoor coil continuously and cycles the plurality of heating elements (including the adjustable output heating element as shown by shaded regions R3, R4 and R5) in order to meet the load demand of the building.
In accordance with the present invention, the air supply temperature can be maintained at a substantially constant temperature, both during first and second stage heating, by use of an adjustable output heating element in combination with additional fixed output heating elements.
Additionally, the opportunity for installer-induced error can be avoided by using a factory installed temperature sensor at the downstream side of the indoor coil or an off-the-shelf outdoor temperature sensor.
While the present invention has been described with reference to a particular preferred embodiment, it will be understood by those skilled in the art that various modifications and the like could be made thereto without departing from the spirit and scope of the invention as defined in the following claims.
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A method and apparatus for controlling supplemental heat added to the air stream passing from an indoor coil to an air supply duct of a heat pump system, the heat pump system being of the type that includes an indoor thermostat having a first set point for initiating heat supplied by the indoor coil and a second set point for initiating additional heat supplied by supplemental heating means. The supplemental heating elements include an adjustable output heating element for heating air passing from the indoor coil to the air supply duct. The coil discharge temperature of the air stream heated by the indoor coil is determined at a position between the indoor coil and the supplemental heating means. The adjustable output heating element is selectively energized in response to the coil discharge temperature, independent of the second set point of the indoor thermostat.
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BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to the filtering of fluids and, more particularly, to an improved pleated filter as well as a method and apparatus for fabricating such filter.
The invention relates generally to the subject matter disclosed in U.S. Pat. Nos. 3,313,665, 3,377,220, 3,552,400 and 4,390,031. The subject matter disclosed in each of these patents is expressly incorporated herein, in its entirety, by reference.
2. Discussion of the Prior Art
It has long been recognized that pleated filters provide increased filter surface area as compared with filters having no pleats and the same exterior dimensions. However, there are a number of practical disadvantages inherent in prior art pleated filters which have severely limited the practical commercial use of such filters. For examle, the filter material which is to be pleated must be sufficiently structurally self-supporting so as to retain its shape when pleated. Thus, when thin membrane-like sheets of material are called for to perform the necessary filtering function, the structural integrity of the filter in pleated form requires the use of much thicker material. This occupies far more space than would be required for the thinner sheet of filter material, and also restricts the number of pleats permitted per linear inch of filter employed. Prior art attempts to provide a large number of pleats per inch have resulted in a closing off of the pleats, thereby restricting the available filter surface area. In addition, it has been impossible, heretofore, to provide a unitized depth filter in pleated form.
OBJECT AND SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a pleated filter structure which permits a larger number of pleats to be provided per given filter length without sacrificing filtering efficiency. It is similarly an object of the present invention to provide an apparatus and method for fabricating such a filter structure.
It is another object of the present invention to provide a pleated filter structure wherein filter material in the form of soft sheets and membranes may be pleated and still function without a loss of filtering efficiency. It is another object of the present invention to provide a method and apparatus for fabricating such a filter.
It is another object of the present invention to provide a filter structure, and a method and apparatus for fabricating such a filter structure, which provides complicated high efficiency filtering at a low cost.
A further object of the present invention is to provide a multi-stage filter in a unitized structure which, by virtue of pleating, offers a large filter surface area and in which the various stages may be of the same or different porosity. It is likewise an object of the present invention to provide a method and apparatus for fabricating such a filter.
In accordance with the present invention, a pleated filter is fabricated from a sheet having two or more adjacent layers. The individual layers may be the same material or materials of different porosity. If one layer is made of material which is too thin to support a pleated configuration on its own, one or more additional layers are selected to provide the necessary structural support. In the preferred embodiment described herein, a layer of filter material is inserted between two layers or bands of tow material. The resulting plural layer sheet is conveyed through a pneumatic conveyor having a passage with a transverse cross-section corresponding to the desired outer configuration of the resulting filter. The sheet is conveyed through the passage by means of a conveyor gas which is vented at a venting location in which the passage is enlarged in cross-section. The sheet is withdrawn from the passage at a lower linear speed than the speed at which the materials are delivered to the passage so that the sheet is caused to be crimped into adjacent plates, particularly at the enlarged venting location. Since the filter layer is caught between the tow layers, it is pleated along with the tow layers. The tow keeps the filter sheet pleats from closing off on one another while themselves presenting filtration media on both sides of the pleated sheet. The resulting structure is a laminated pleated filter having three stages of filtration.
The resulting filter structure increases filtration capability without increasing pressure drop and offers a unitized three stage filter structure. The latter property is useful for coalescing water from fuel. In addition, the filter of the present invention permits soft or membrane-like sheets of filter material to be pleated and retain their structural integrity. Further, complicated high efficiency filters may be fabricated at a relatively low cost.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, features and many of the attendant advantages of the present invention will be better understood from the following detailed description when considered in connection with the accompanying drawings wherein like parts in each of the several figures are identified by the same reference numerals, and wherein:
FIG. 1 is a view in longitudinal section of apparatus according to the present invention for fabricating a filter of the present invention;
FIG. 2 is a partially diagrammatic view in longitudinal section of another apparatus according to the present invention and illustrating one method of the present invention for fabricating a filter;
FIG. 3 is an enlarged detailed view in longitudinal section of a filter fabricated in accordance with the method and apparatus illustrated in FIG. 2;
FIG. 4 is a partially diagrammatic view in longitudinal section of the pleat-forming apparatus of FIG. 2 employed with different material delivery apparatus in accordance with another method of the present invention;
FIGS. 5, 6 and 7 are respective views in prospective of different external shapes of pleated filters which can be fabricated in accordance with the method and apparatus of the present invention; and
FIG. 8 is a view in longitudinal section of the pleat-forming apparatus of FIG. 2 employed in conjunction with a different material delivery system in which a filter sheet is pre-crimped in accordance with still another aspect of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring specifically to FIG. 1 of the accompanying drawings, a filter pleating apparatus according to the present invention includes an elongated hollow member 10 having a longitudinally extending central bore 11. The bore 11 is closed at one end by means of a plug member 13 through which a longitudinally-extending bore 15 is defined. Bore 15 has a fitting disposed at one end thereof and receives an elongated tube 17 at its other end. Tube 17 extends through bore 11 beyond the opposite end of tubular member 10. That opposite end of tubular member 10 engages a generally cylindrical member 19 having a longitudinally-extending bore in which tube 17 is supported. The end of member 19 remote from tubular member 10 is hollow and is provided with a generally cylindrical insert 20 which sub-divides the hollow interior of member 19 into a venting chamber 21 and an end chamber 23. Insert 20 is provided with a recess which receives and supports the distal end of tube 17, and is also provided with a plurality of flow passages 25 which provide flow communication between the venting chamber 21 and the end chamber 23. The exterior of member 19 tapers so that the outside diameter of member 19 is reduced, as compared to the outside diameter of tubular member 10, in the region surrounding the vent chamber 21 and end chamber 23. A plurality of radially-extending passages 27 are defined through member 19 in venting region 21 so that the environment immediately surrounding the member 19 at venting region 21 communicates with the venting region and, via passages 25, with the end region 23 which opens to atmospheric pressure. In addition, tube 17 provides flow communication from bore 15 in member 13 to the open end chamber 23 via the bore 29 in insert 20.
A hollow outer member 30 is disposed concentrically about member 19 and is radially spaced therefrom to define an elongated annular passage 31. The inner diameter of member 30 increases in a region 33 opposite the decreasing outer diameter of member 19 so that passage 31 diverges in this region before entering a venting station 35 which is co-extensive with venting chamber 21. A plurality of vent passages 37 extend radially outward through the wall of member 30 at venting station 35 so that the venting station includes vent passages 27 extending radially inward and vent passages 37 extending radially outward therefrom.
Downstream of vent station 31, there is disposed a heating station 40 demarked by a circumferential recess 41 defined in the outer wall of member 30. A plurality of passages 43 extend from recess 41 generally inwardly and upstream into the heating station 40. Passages 43 are angularly spaced about the periphery of the heating station in recess 41.
Just downstream of heating station 40 is a cooling station 45 demarked by a circumferential recess 47 defined in the outer wall of member 30. A plurality of passages 49 extend inwardly into cooling station 45 from recess 47 in a generally radial direction. An outer sleeve member 42 is disposed concentrically about the downstream end of member 30, co-extensive with heating station 40 and cooling station 45. A fitting 44 is defined through sleeve member 42 so as to communicate with recess 41 at heating station 40 so that steam or other suitable hot gases may be supplied to recess 41. Another fitting 46 is defined in sleeve member 42 and communicates with recess 47 so that air or other cooling gas may be supplied to that recess proximate the cooling station 45.
The upstream end of member 30 is surrounded by an intermediate sleeve member 50 having a generally frusto-conical inner surface which surrounds the downstream end of elongated hollow member 10. A nozzle forming member 51 also surrounds the downstream portion of member 10 and has an outwardly facing frusto-conical surface which is co-extensive with and radially spaced from the inner frusto-conical surface of member 50. The spacing between these two surfaces defines a generally frusto-conical nozzle 53 having a downstream end which terminates at the upstream end of annular passage 31. The upstream end of nozzle 53 terminates in an annular supply channel 55 which is defined between nozzle-forming member 51 and a surrounding sleeve 57. A suitable fitting 59 is defined through sleeve 57 to permit air under pressure, or other suitable conveyor gas, to be injected into passages 31 through supply channel 55 and nozzle 53. Nozzle-forming member 51 is also radially spaced from the exterior of member 10 so as to define an annular passage 60 which extends in a longitudinal direction to terminate at the upstream end of annular passage 31. The upstream end of annular passage 60 is open to receive material, as indicated by arrows 61, which forms the pleated filter of the present invention.
In the manner described below, a sheet of filtering material may be fed with tow material into annular passage 60 along the path designated by arrows 61. Continuous filamentary tows of various materials, including cellulose acetate, viscose, nylon, etc. have heretofore been developed and commonly employed in fabricating filters. For example, cellulose acetate tows have been employed for making cigarette filters, and the like. Generally, the fibers of the two are formed with spinneret devices, and the strands exiting from such spinneret devices are bunched together to form a "raw tow" which is wound, or folded, into a bale for subsequent processing. The subsequent processing operations usually involve, in addition to unwinding of the raw tow, spreading apart of the fibers of the tow to provide a relatively thin fiber layer, tensioning the fibers to eliminate the crimps therein, impregnating the fiber layer with a plasticizer which can bond adjacent fibers together, and gathering the bonded layer through a suitable funnel, or the like, to form a treated cylindrical tow having filaments therein which are primarily oriented in a longitudinal direction.
The above specific discussion of prior tow treating techniques is incorporated herein merely to explain the type of two which can be used in accordance with the preferred embodiment of the present invention. It is to be clearly understood, however, that the invention is not specifically limited to formation of products from tows, much less previously available tows, nor are filaments formed from spinnerets necessarily as prerequisite starting material for the invention. Instead, various fibrous materials, filaments, and the like can be used as base materials and the starting form thereof can be widely varied. At the same time, the use of filaments, and a two containing the same, facilitates certain method steps hereof and, since tows of spun filaments are readily available or can be easily formed at comparatively low cost, a filamentary tow provides a desirable base or starting element for use in accordance with the present invention. In any case, the material to be treated, including at least two layers of material disposed adjacent one another in the manner described below, is delivered to annular nozzle 61. The walls of nozzle 61 and passage 31 may be coated with polytetrafluoroethylene (Teflon) or other such material, if desired, to provide reduced friction therein. The delivered material is conveyed through passage 31 pneumatically by means of a conveying gas delivered under pressure to fitting 59. The conveying gas is passed through supply channel 55 to nozzle 53 which directs the conveying gas into annular passage 31. The angle made by the frusto-conical nozzle 53 with the longitudinal axis of the unit falls within the range of approximately 0° to 25°, and preferably is about 15°. The conveying gas, which may be air, for example, is at a sufficiently high pressure to pneumatically convey the tow through annular passage 31 in a formation substantially conforming to the annular cross-section of that passage. However, the pressure of the gas deliverd to convey the material must be sufficiently low so that all, or substantially all, of the conveying gas can be vented through vent passages 27, 37 in venting region 35. The conveyor gas transports the material in the form of sheet laminations into the venting station where the release or venting of the conveyor bends the laminated sheet combination back and forth between member 19 and member 30. In other words, the annular jet of conveyor gas creates a suction effect at the upstream end of annular passage 31 which draws the material through annular passage 60 at a velocity proportional to the velocity of the conveyor gas through channel 31. Further transport of the material, after the conveyor gas has been exhausted from venting region 35, is effected from externally of the illustrated apparatus (for example, by means of a pulling device such as the type illustrated and described in the aforementioned U.S. Pat. No. 4,390,031). After passing the venting station 35, the crimped or pleated material is subjected to heating by means of a heated gas injected through fitting 44, recess 41 and passages 43 into direct contact with the radially-outer portion of the material. In addition, hot gas delivered at the fitting in bore 15 of member 13 passes through tube 17 into end region 23 wherefrom it is caused to flow through passages 48 into direct contact with the radially-inner side of the material at heating station 40. The heating gas is preferably steam under pressure, the major portion of which condenses on contact with the material to provide the heat necessary to render the tow boundable at points of contact of the individual filaments of the tow in well-known manner.
After the material has been heated at heating station 40, it is passed through cooling station 45 at which point coolant gas, such as air, is introduced to bond the tow into a self-sustaining, dimensionally stable filter having the ultimate predetermined cross-sectional size and shape of the annular passage at stations 40 and 45. The coolant air is delivered from fitting 46 to recess 47 and from there into contact with the material through passages 49.
After passing through the cooling station 45, the material has been formed into a self-sustaning, dimensionally stable, pleated filter filter in which the pleats have fold lines extending transversely to the direction of travel through the apparatus illustrated in FIG. 1. The filter is withdrawn from the apparatus at an average linear speed which is lower than the linear speed of the incoming material fed into annular passage 60. When the filter is withdrawn at an average liner speed which is less than the incoming linear speed, the material is reoriented within the confined passage into adjacent and overlapping relation in generally successive pleats which extend transversely of the direction of travel. This reorientation initially occurs prior to contacting of the tow with the heated gas. regardless of the relative rate of withdrawal of the resultant filter structure, due to the pneumatic feeding technique, at least a major portion of the crimp initially present in the material is retained by the material upon exiting from the apparatus. Moreover, secondary crimp is imparted to the material by the preferred processing techniques of the present invention and is retained by the material in the resulting filter structure. The relationship between the average linear speed of the incoming material to the average linear speed of the withdrawn filter structure can vary over a considerably wide range. For most applications, this ratio will vary from between 10:1 to 100:1 in order to provide desirable filter products according to the present invention. The withdrawing rate of the filter structure may be readily controlled by selective operation of the pulling means noted above.
A generally similar type of pleating apparatus is illustrated on the left hand side of FIG. 2 to which specific reference is now made. The material delivered to the apparatus includes a bottom tow band 67, a top tow band 70, and a sheet of filter material 65. The sheet of filter material is delivered from a roller 66 on which it is stored and is sandwiched between the upper tow band 70 and bottom tow band 67 at roller 68. The composite sheet member, comprising the three layers 65, 67 and 70, is delivered by means of rollers 71 and 72 to the annular inlet passage 60 of the pleating apparatus. The laminated sheet of material is conveyed through passage 31 by means of the conveyor gas delivered from nozzle 53 and vented at venting station 35. The material is caused to crimp or pleat at venting station 35 in the manner described above and is then passed through the heating zone or station 40 and cooling zone or station 45 before exiting the pleating apparatus.
The filter structure which is delivered by the pleating apparatus in FIG. 2 is generally desingated by the reference numeral 73 and is illustrated in greater detail in FIG. 3. Specifically, the filter structure 73 is a sheet-like member formed into a hollow cylindrical structure having three adjacent layers 65, 67 and 70. A multiplicity of successively adjacent pleats each includes the three layers 65, 67 and 70 and the pleats are provided with fold lines extending transversely of the longitudinal dimension of the cylindrical structure 73. Thus, if the filter material in sheet 65 is membrane-like or otherwise too soft to structurally sustain a pleated configuration, the tow or other strengthening materials 67, 70 provide the necessary structural support for the pleats. Since the filter material 65 is trapped between the two strands of tow 67, 70, the tow material keeps the pleats in the filter sheet 65 from closing off one another. In addition, since the tow material itself serves as a filtration medium, a three-stage filter structure is provided through the thickness of the resulting filer structure 73. The two tow materials may be the same or different, and the three materials 65, 70 and 75 may have the same porosity or different porosities.
Referring specifically to FIG. 4 of the accompanying drawings, the apparatus illustrated therein is basically similar to that illustrated in FIG. 3 with the exception of the manner of delivery of the three layers of material to the pleating apparatus. Specifically, the filter layer 65, in the embodiment of FIG. 4, is derived from an extruder 75 and delivered into sandwiched relation between the top tow band 70 and the bottom tow band 67 between respective rollers 77 and 79. In all other aspects, the embodiment illustrated in FIG. 4 is the same as that described above in relation to FIGS. 1 and 2.
The generally hollow filter structure 73 is illustrated in perspective in FIG. 5 and derives its hollow cylindrical configuration from the cross-sectional configuration of the annular passage in the pleating apparatus. It is to be understood, however, that this transverse cross-section of the passage in the pleating apparatus may be varied so as to provide a solid three-layered sheet 80, such as illustrated in FIG. 6, or the hollow rectangular or square structure 81 illustrated in FIG. 7. In other words, in order to produce the filter construction 80 illustrated in FIG. 6, the passage through the pleating apparatus has a generally rectangular cross-section which is elongated in one dimension transversely of the flow direction through the apparatus. In order to provide the hollow rectangular construction 81 of FIG. 7, the cross-section of the passage 31 and its enlarged downstream counterparts is a rectangular annulus, as opposed to the circular annulus which provides the hollow cylindrical structure 73 illustrated in FIG. 5.
Still another embodiment of the present invention is illustrated in FIG. 8. In that embodiment, the pleating apparatus is essentially the same as that illustated in FIGS. 2 and 4. The major difference in the embodiment of FIG. 8 concerns the fact that the filter layer 65 is partially pre-crimped between crimping rollers 90 and 91 before the filter layer 65 is sandwiched between the top and bottom tow bands 70 and 67, respectively. This pre-crimping of the filter layer 65 facilitates the pleating process in the pleating apparatus.
It is also possible to practice the present invention by utilizing two filter layers instead of three, the two layers being folded together to form the requisite pleats. Likewise, more than three layers may be employed, although the thickness of the pleats under such circumstances may be too great to permit a meaningfully large number of pleats to be disposed within a given length of the filter structure. Of course, it is desirable to maximize the number of pleats per given length of filter structure so as to maximize the presented filter surface area per length of filter structure.
The method and apparatus for producing the filter in accordance with the present invention is a variation of the method and apparatus described in the aforementioned U.S. Pat. No. 4,390,031. That method and apparatus, in turn, is a variation of the method and apparatus described in the aforementioned U.S. Pat. No. 3,313,665. In the process disclosed in the latter patent, the density of the resulting product is determined by the ratio of the linear speed of the exiting material to the linear speed of the incoming material. In the case of a laminated sheet member material, as used with the present invention, one may calculte the number of pleats per inch by determining the wall thickness and the ratio of the velocities of the incoming material and the exiting material. In other words, exiting material having a one inch wall thickness in a pleating apparatus with a speed ratio of 100:1 produces a resulting structure with fifty pleats to the inch. The total surface area of the resulting filter structure is the length of a pleat times twice the width of the sheet. Thus, with an output filter structure having a circumference of ten inches and a wall thickness of one inch, employed in a pleating apparatus with a speed ratio of 100:1, a filter surface area of 500 square inches per linear inch would be the result. This permits a surface area increased by pleating which far exceeds any such increase that has been produced in the prior art. With this high surface area, the filter sheet 65 can be made very dense, and fine fibers, in the range of 1 micron can be employed while still maintaining a useful porosity.
The description set forth above relates to feeding a filter sheet between two strands of tow, or alternatively, adjacent one strand of tow. however, the resulting sheet material may be formed using a melt blown process. Under such circumstances, fine fibers are extruded between the tow to form the filter sheet. One advantage of the melt blown process is that the sheet of filter material is attached to the tow prior to entry into the pleating apparatus and filled in between the strands of fiber making up the tow, thereby increasing the surface area beyond that which would be achieved with the straight sheet approach. In addition, it has been demonstrated that the melt blown fibers can be made much finer than is possible with conventional fiber-making techniques. The fibers adhere to the tow in the same manner that hot melt adheres because the fibers are above the melt temperature.
The method described above for fabricating a filter structure results in tubes which are flexible and which can be formed about a mandril to make a spiral filer configuration. The spiral configuration increases the surface area by a factor of pi, so that any advantages achieved with the present technique can be further increased by a little over three times utilizing the spiral approach.
I have fabricated numerous types of filter structures using the pleating apparatus and method disclosed for the present invention. One structure I have fabricated employs nylon as the two outer tow layers surrounding a sheet of Delnet. Another structure employed nylon with Reemay, the latter being used in two different filter constructions wherein a two layer structure and a three layer structure were fabricated.
From the foregoing description, it will be appreciated that the invention makes available a novel multi-stage filter wherein each stage is made up of a different layer of material. The filtration is increased without increasing the pressure drop and a unitized structure is provided for the multi-stage combination. The unitized three-stage filtration stucture is particularly valuable for coalescing water from fuel. In addition, the filter structure in accordance with the present invention permits sheets of soft filter material, such as membranes, to be utilized in a pleated filter structure in spite of the fact that the sheet, of itself, is not structurally capable of supporting a pleated construction. Finally, the apparatus and method for making such filter structures is simple and inexpensive and permits highly efficient filters to be fabricated.
Having described several embodiments of a new and improved filter structure and method and apparatus for fabricating same, it is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the disclosure set forth herein. It is therefore to be understood that all such variations, modifications and changes are believed to fall within the scope of the invention as defined by the appended claims.
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A filter for separating constituent components of fluids includes a plural-layer sheet-like member which is multiply pleated to provide layers of the same or different porosity or to provide structural support layers for pleating a soft or membrane-like filter layer. The multiple layers may be pre-joined or delivered from individual locations to a pneumatic conveyor passage of predetermined cross-section through which the adjacent layers are conveyed by a conveyor gas. The layers are crimped to form pleats by withdrawing the material at a lower linear speed than that at which it is supplied to the passage. Pleating is facilitated by venting the conveyor gas at a passage section of enlarged cross-section. The pleating material is subjected to a hot gas, such as steam, and then cooled by a cooling gas to effect bonding of the layers in the pleated state.
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RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional Application Ser. No. 60/725,901 filed Oct. 12, 2005, U.S. Provisional Application Ser. No. 60/725,006 filed Oct. 6, 2005, and also U.S. Provisional Application Ser. No. 60/675,315 filed Apr. 27, 2005. The contents of said applications are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to proximity sensors. More specifically, the invention relates to a sensor for detecting a relative distance of an object to the sensor by detecting changes in charge transfer.
BACKGROUND OF THE INVENTION
[0003] Proximity sensors for detecting an actual or relative distance between the sensor and an object are known in the art. For example, U.S. Pat. No. 6,621,278 to Arie Ariav discloses a method of measuring a distance by transmitting a cyclically-repeating wave. The wave is then received at a second location in the medium. The system detects a predetermined point in the cyclically-repeating wave that is received at the second location and continuously changes the frequency of transmission of the cyclically-repeating energy wave in accordance with the detected point of each received cyclically-repeating wave received at the second location such that the number of waves received at the second location is a whole integer. The change in frequency to produce a measurement of the predetermined parameter is used to determine the distance the wave has traveled. However, this system has drawbacks, particularly in that the sensor is unduly complex both in electronic implementation and in sensor construction.
[0004] Other types of detectors, primarily for detecting the presence or absence of an object, use ultrasonic and radio frequency transmitters and detectors that receive reflected energy when an object is present in an area of interest. These detectors however cannot be used practically to detect a relative or actual distance, particularly in very short distances. In certain settings, the amount of RF energy generated by these types of device is unacceptable due to interference. Moreover, some people have concerns about constant exposure to RF energy.
[0005] Many applications require low power consumption and detection of a relative distance within a range of interest. For example, cushions for wheelchairs must be inflated to a pressure that is sufficient to properly immerse the person in the cushion to prevent the formation of decubitus ulcers on the person in the wheelchair. However, often the people bound to the wheelchair do not have the ability to feel when they are properly immersed in the cushion, such as a paraplegic or quadriplegic person. For those people, others must periodically check the person's immersion within the cushion to ensure the person is not in an overinflated state, such that only a small portion of the person's body is bearing their weight, or in an underinflated state, such that the person has “bottomed out” and is no longer supported entirely by the cushion. Similarly in a cushion not inflated with air, problems also exist when determining the proper cushion immersion. However, presently, no acceptable means of detecting the immersion of a person in a cushion exists. Only indirect measurement of pressure internally in the cushion is available. This type of measurement is dependant upon the materials of construction and structural conformation all creating significant limitations in the applicability of the measurement.
[0006] Likewise, people bound to hospital beds must avoid decubitus ulcers when confined to the bed for long periods of time. To accomplish this, inflation mattresses are commonly used, and the inflation level of the mattress must be monitored in order to maintain the proper inflation level to prevent overinflation or underinflation of the mattress. Moreover, because the person's weight is concentrated over their entire back side, multiple locations must be checked for underinflation or overinflation. As a result, a sensor which is divided into zones to check the immersion of the patient within the mattress is needed.
SUMMARY OF THE INVENTION
[0007] The present invention comprises an immersion sensor for use with a cushion or mattress for measuring the depth of immersion of a person within the cushion or mattress comprising a sensor, a ground and/or shield and a circuit for measuring capacitance. The sensor comprises a sheet of conductive material, and the ground comprises a second sheet of conductive material. The circuit is adapted to send short bursts of electrical current to the sensor and the reference capacitor. The circuit is further adapted to measure the length of time the burst of current takes to charge the capacitor. Based upon the measured time, the circuit calculates the proximity of the object based upon the time taken to charge the capacitor. The present invention also comprises a method that may be implemented with the immersion sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an exploded perspective view of a wheelchair cushion proximity detection device according to an embodiment of the present invention;
[0009] FIG. 2 is a plan view of the conductive and nonconductive layers of the proximity detection device according to an embodiment of the present invention;
[0010] FIG. 3 is a diagram of a circuit according to an embodiment of the present invention;
[0011] FIG. 4 is a diagram of a circuit of a charge transfer device according to an embodiment of the present invention;
[0012] FIGS. 5A-5D are a flow chart showing the operation of the hardware and software of the circuit of FIG. 3 ;
[0013] FIG. 6 is an exploded perspective of a proximity detector for a bed air cushion according to an embodiment of the present invention;
[0014] FIG. 7 is a diagram of a circuit according to another embodiment of the present invention;
[0015] FIG. 8 is a diagram of a sensor placement on a bed cushion proximity detector according to an embodiment of the present invention;
[0016] FIG. 9 is a diagram of a circuit according to another embodiment of the present invention;
[0017] FIG. 10 is a diagram of a sensor placement on a bed cushion proximity detector according to yet another embodiment of the present invention;
[0018] FIG. 11 is a diagram of a sensor placement on a bed cushion proximity detector according to yet another embodiment of the present invention;
[0019] FIG. 12 is an exploded perspective view of an automatically adjusting wheelchair cushion according to an embodiment of the present invention;
[0020] FIG. 13 is a perspective view of an embodiment of the device including a first sensor of relatively large area and a second sensor of relatively small surface area according to an embodiment of the present invention;
[0021] FIG. 14 is a perspective view of an embodiment of the device including a first sensor of relatively large area and a second sensor of relatively small surface area with a ground plane according to an embodiment of the present invention;
[0022] FIG. 15 is a diagram of a circuit for operating the embodiment of FIG. 14 ;
[0023] FIG. 16 is diagram of an embodiment of the present invention including a visual display device; and
[0024] FIG. 17 is a diagram of a sensor placement on a bed cushion proximity detector according to yet another embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0025] While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.
[0026] The preferred embodiment of the present invention is a proximity sensor that utilizes charge transfer measuring technology and large-area capacitive sheets to determine the distance of an object from the capacitive sheet. The charge transfer measurement is employed with a short, low duty cycle burst of power. Burst mode permits power consumption in the low microamp range, thereby dramatically reduces radio frequency (RF) emissions, lowers susceptibility to electromagnetic interference (EMI), and yet permits excellent response time. Internally, it is preferred that the signals are digitally processed to generate the required output signals. The charge transfer measurement device switches and charge measurement hardware functions are preferably all internal to the charge transfer measurement device.
[0027] To that end, the invention will be described, by way of example and not by limitation, in reference to a cushion for a wheelchair. Referring to FIG. 1 , there is shown an inflatable cushion 10 , for example the cushion described in U.S. Pat. No. 4,541,136. Placed below the cushion is a sensor 12 according to the present invention to detect the immersion of a person within the cushion. The sensor 12 comprises two exterior sheets of neoprene rubber 14 . Sandwiched between the sheets of rubber are thin layers of foam 16 and between the foam 16 is a sensor layer 18 .
[0028] The sensor layer 18 of FIG. 2 comprises a conductive sheet 20 adhered to a nonconductive sheet 22 . The conductive sheet 20 is preferably made from copper, and the nonconductive sheet 22 is preferably made from a polyester film. The sensor layer 18 may also be made from any other conductive material, such as a conductive polymer. The conductive sheet 20 when made from copper preferably has a thickness of about 0.0005 of an inch. The conductive sheet 20 is interrupted, preferably by etching or die cutting, along an area 24 to form a sensor area 26 and a grounding plane area 28 . While the sensor layer 18 is described as copper and polyester sheets, the nonconductive sheet is not required and may be omitted and the conductive sheet may be made from any conductive material, such as a conductive braid, mesh or screen printing a conductive material onto a nonconductive base. Additionally, while the sensor area 24 is shown as rectangular, the sensor area 26 may be appropriately shaped and located in order to provide the optimum geometry to the object to be sensed. In the example of FIG. 2 , the sensor area is confined to a rear portion of the sensor where a person's buttocks would be located when seated in the wheelchair. Since most of a person weight is distributed in this location while seated, this located is at the greatest danger of bottoming out. However, it is within the scope of the present invention to provide a sensor at any location or multiple locations of the seating area.
[0029] The problem solved by the ground layer with using charge transfer or capacitive technology with wheel chair cushions is that there is no good ground to use as reference. The grounding plane area 39 being in the area around the sensor area 26 allows a capacitance measurement to be made relative to the distance between the person and the sensor and ground areas 26 and 28 . The present invention is attached to a circuit 30 as shown in FIG. 3 . The circuit generally comprises a microcontroller 32 , such as a 16LF818 available from Microchip Technology, Inc. of Chandler, Ariz. The microcontroller 32 is powered by a 3.5 volt battery 34 . Attached to the enable line 36 of the microcontroller 32 is a voltage regulator 39 for regulating the input voltage to the microcontroller 32 . Attached to the clock line 38 and the data line 40 is a charge transfer sensor 42 . The data line 40 transmits data from the charge transfer sensor 42 to the microcontroller indicting the distance of an object, in this case a person's buttocks, from the sensor area 26 . The data is preferably in the form of a hexadecimal number representative of the relative distance of the person from the sensor area. In the preferred embodiment, the charge transfer sensor 42 is a QProx QT117 available from Quantum Research of Hamble, Southampton, United Kingdom. A ground line 44 is also connected to the charge transfer sensor 42 , as well as to the grounding plane 28 . The capacitive sensor 42 also requires a capacitor 46 , having a capacitance C s , attached to two lines of the sensor 42 . The capacitance of the capacitor 46 is preferably 0.022 μF and a temperature stable dielectric such as COG, but such value will change based upon the size and the application of the sensor.
[0030] Also attached to the microcontroller 32 are various outputs to alarms and indicators 48 , inputs from an on/off switch 50 and an operator input switch 52 , and inputs from other controls 54 , such as if the circuit 30 is used as a feedback loop to automatically control the inflation of the cushion, as described below.
[0031] Referring to FIG. 4 , the charge transfer sensor 42 employs a short, low duty cycle burst of charge-transfer cycles with a burst controller 58 and amplifier 62 to acquire its signal. Internally the signals are digitally processed with an analog to digital converter (ADC) 60 to generate the required output signals. The charge transfer sensor 42 switches and charge measurement hardware functions are all internal to the sensor 42 . The ADC 60 is 14-bit single-slope switched capacitor ADC including both the required sensor 42 charge and transfer switches in a configuration that provides direct ADC conversion. The burst length is inversely proportional to the rate of charge buildup on the capacitor 46 (C s ), which in turn depends on the values of C s , C x (the load capacitance of the sensor) and V cc . V cc is used as the charge reference voltage. Larger values of C x cause the charge transferred into C s to accumulate more rapidly. As a result, the values of C s , C x and V cc should be fairly stable over the expected operating temperature range.
[0032] The internal ADC 60 treats C s as a floating transfer capacitor. As a direct result, the sensor 26 can be connected to either SNS1 or SNS2 with no performance difference. The polarity of the charge buildup across C s during a burst is the same in either case. C s must be of within a certain range for proper operation. It is important to limit the amount of stray capacitance on both terminals, especially if the load C x is already large, for example by minimizing trace and wire lengths and widths so as not to exceed the C x load specification and to allow for a larger sensing electrode size if so desired. The circuit board traces, wiring, and any components associated with or in contact with SNS1 and SNS2 will become proximity sensitive and should be treated with caution.
[0033] The microcontroller 32 operates according to the flow chart of FIG. 5 . In a first step, the device is powered on 100 and enters a continuously monitoring state 102 . From this state, the microcontroller 32 monitors whether an input operator input switch 52 has been depressed in decision step 104 . If it is has not, the microcontroller 32 returns to the monitoring state 102 . If the switch 52 has been depressed, the next step is to determine whether the depression was for three seconds or less in decision step 106 . If for three seconds or less, the battery health is checked in step 108 and a present reading of the distance of the person from the sensor area 26 is determined in step 110 .
[0034] If a button 52 is determined to have been pressed greater than three seconds in step 106 , then in step 112 , the microcontroller 32 causes an alarm 48 to beep momentarily and proceeds to step 114 where the circuit again determines of the button 52 has been depressed for more than three more seconds. If so, the microcontroller 32 cycles through a series of five sensitivity settings as indicated to the user by a rapid succession of beeps of the alarm 48 in step 116 . The sensitivity setting is then stored in step 118 and the circuit continues to step 110 to read the present distance.
[0035] If in step 114 it is determined that the button 52 has not been depressed for an additional three seconds, a value indicating the present distance is stored as the preferred set point in step 120 , and the circuit sounds an alarm and continues to step 110 to read the present distance.
[0036] If in step 110 , the present value of the distance of the person from the sensor area 26 is not readable, the circuit continues to step 122 and flashes yellow and red LEDs alternatively. If the value is readable, the microcontroller 32 continues to step 124 and sets a tolerance above and below the current setpoint which will be considered within acceptable range from the setpoint. Next, in step 126 , the microcontroller 32 decides whether the present reading is within range or above or below range.
[0037] If the reading is above range, in step 128 , the microcontroller 32 determines whether the current reading is greater than or equal to two counts over the previously chosen and stored sensitivity plus the setpoint. If the condition is true, the microcontroller 32 proceeds to step 130 where the microcontroller 32 determines it is not presently being used and goes to sleep until a reading is in the normal range. If the condition is not true, the microcontroller 32 flashes a yellow LED 48 to indicate that the cushion is overinflated. In either event, the microcontroller 32 next optionally proceeds to step 134 , where it logs the current condition date and time. If the embodiment is not one in which the data indicating inflation status is logged, the microcontroller will proceed to step 136 .
[0038] In step 136 , if the current reading is below the acceptable range, the microcontroller will flash the red LED 48 and sound an audible alarm 48 to indicate underinflation if the current reading is the second consecutive reading to determine underinflation and proceeds to step 134 .
[0039] After step 134 , the microcontroller 32 determines whether a user has pushed the button 52 to silence the audible alarm 48 in step 138 . If yes, the microcontroller 32 proceeds to step 140 and disables the audible alarm 48 until a second button push or a current sensor reading shows a reading with the acceptable range. After steps 138 and 140 , the microcontroller 32 proceeds to step 102 .
[0040] If it is determined in step 126 that the setpoint is within the acceptable range, the microcontroller 32 continues to step 142 where the microcontroller 32 determines if the present reading was initiated by a button 52 press. If yes, in step 144 the green LED 48 is flashed and the microcontroller 32 returns to the monitoring state in step 102 . If no, in step 146 , the microcontroller 32 reinstates the timer and return to step 102 .
[0041] Returning back to step 102 , if in the monitoring state ten minutes have elapsed, the microcontroller 32 will initiate a current reading automatically by proceeding to step 148 by performing a battery check and proceeding to step 110 .
[0042] As another example shown in FIG. 6 , the sensor can be used in a hospital bed to determine whether a patient has bottomed out when using an inflatable air mattress. In this instance, the bed comprises a bed frame 200 comprising a spring support 202 . Placed upon the spring support are a shield plane 204 and a sensor plane 206 . Upon the sensor plane 206 is placed an air mattress 208 . The shield plane 204 acts to isolate the metallic items of the bed 200 , particularly the spring support 202 , from the sensor plane 206 . The sensor plane 206 in its simplest application comprises a single sheet of conductive material, as with the previously discussed embodiment. The driven shield isolates the metal items of a bed and chair below the sensor plane 206 . In a device without a driven shield the effect of surrounding metal is subtracted by the user creating a setpoint based on the desired immersion level and the relative reading observed at that immersion.
[0043] Just as with the wheelchair cushion proximity detector, the circuitry 30 operates in the same manner except that the shield plane 204 is driven to provide isolation from the metallic structure of the bed. The distance between the sensor plane 206 and the shield plane 204 is preferably about ⅛″ to about ⅜″. A problem posed by the hospital bed situation is the amount of metal in the bed and mattress support structure. The driven shield under the sensor or sensor area in the case of multiplexed units (described below) shields the sensor plane 206 in that direction of the location of the shield plane 204 giving increased sensitivity in the desired direction and ignoring changes in conductive materials and noise generating devices with position changes of the relative position of the device with the bed or other devices.
[0044] In this regard and referring to FIG. 7 , the original circuit 30 is modified to form circuit 30 ′. The numerals of circuit 30 ′ that correspond to circuit 30 are unchanged. However, the circuit 30 further comprises an amplifier 302 which is driven from an output of the charge transfer sensor 42 and serves to drive the shield plane 204 to isolate the sensor plane 206 from the metal portions of the bed 200 .
[0045] In another embodiment shown in FIG. 8 , the bed 200 may be equipped with multiple sensors 400 - 414 in the sensor plane 206 . For example, the first sensor 400 would be placed in the area of the patient's head, two more sensors 402 and 404 in the area of a patient's shoulders, yet another sensor 406 in the area of the patient's buttocks, and finally two more sensors 408 and 410 in the area of the patient's feet. Entrapment sensors 412 and 414 are also located near the bed rails to provide an indication that the patient has rolled to one side of the bed and has possibly become entrapped in the railing.
[0046] The sensors 400 - 414 are all conductively attached to a charge transfer sensor to form a single sensor plane 206 . The shield plane 204 is similarly divided into portions that correspond to the size and the shape of the sensors 400 - 414 . The result is that one charge transfer sensor 42 is required for each sensor 400 - 414 .
[0047] To provide the ability to monitor an even greater number of sensors, a circuit 30 ″ as shown FIG. 9 can be implemented. The circuit is identical to the circuit 30 ′ except that a multiplexer 500 is inserted between the output of the charger transfer sensor 204 and a plurality of sensors 206 , 206 ′ and 206 ″. The multiplexer 500 switches from sensor 206 to sensor 206 ′ to sensor 206 ″, in turn, in order to determine the distance of the relevant portion of the lying person from the sensors 206 , 206 ′, 206 ″. In this manner, only one circuit 30 ″ is required to poll a multiplicity of sensors 400 - 414 . Because of timing limitations of available charge transfer sensors, a limited number of sensors can be daisy chained. Also, due to stray capacitance issues the number of sensors that can be reasonably multiplexed, a combination of multiplexed and daisy chained sensors may be implemented in order to maximize the number of sensors. Thus, for example, sixty-four sensors may be implemented by arranging the sensors as eight daisy chains of sensors multiplexed to the circuits 30 ″ with each chain having eight sensors 420 , as shown in FIG. 17 .
[0048] In that regard and referring to FIG. 10 , an embodiment is shown wherein thirteen sensors 500 - 524 are provided which determine the patient's immersion within the air cushion and two more sensors 526 and 528 are provided that determine whether the patient has become entrapped in the bed rails. These sensors 500 - 528 may be either daisy chained, attached to their own circuits or multiplexed. Moreover, a combination of daisy chaining sensors and multiplexing sensors may be performed.
[0049] In FIG. 11 , yet another embodiment is shown wherein the coverage area of the bed is higher, but with fewer sensors 600 - 610 . This arrangement may be more appropriate for monitoring not whether a person is properly immersed, but rather if they are present or absent from their bed. Such an application would be useful in hospitals and nursing homes. Again, these sensors 600 - 610 may be either attached to their own circuits or multiplexed.
[0050] Another application for the present invention defined in the claims is for use as a feedback loop in the auto-inflation or auto-deflation of a cushion for wheelchair. Referring to FIG. 12 , such an embodiment is shown. Specifically, an output of the microcontroller 32 notifies a valve 700 to change positions to add air, release air or remain closed based upon the inflation status of the cushion 10 . The valve 700 is attached to a source of compressed air 702 , which supplies compressed air when an underinflation status is detected. Likewise, when an overinflation status is detected the valve 700 slowly releases air from the cushion 10 until the proper inflation level is achieved. Similarly, in a low air loss cushion for a hospital bed the circuit may similarly serve as a feedback loop to control mattress inflation, such as by providing feedback to a bed blower control.
[0051] In the embodiments shown above, it is necessary to manually “teach” the microprocessor the extents of the travel by indicating the microprocessor the extents of proximity of the detected object. In that manner, the microprocessor can determine a relative proximity of the detected object within the known range. In the embodiment of FIG. 13 , the device may comprise a sensor within a sensor.
[0052] In this embodiment, there is provided a first sensor 800 comprising a large area with respect to a second, smaller sensor 802 . In the embodiment of FIG. 13 , the second, smaller sensor 802 is surrounded by the first, larger sensor 800 . Below the first and second sensors 800 and 802 , and electrically isolated therefrom, is a ground plane 804 and a driven shield The first sensor 800 is made fairly large to anticipate contact points over a surface of interest (for example, the area under a person's buttocks in a wheelchair cushion application). The large sensor 800 gives a reading of charge transfer that is highly dependant on the size of the individual above the sensor. As a result, without manually setting the range of extents of travel of the person in the wheelchair cushion example, it is difficult to determine the precise proximity of a person of unknown size.
[0053] Merely by way of example, a large person may range between a value of 76 and 120 at the extents of travel of that person's proximity to the sensor 800 . A small person may range between values of 100 and 150 at their extents of proximity. Therefore, at the closest extent of travel, a large person may show a reading of 76 and the small person may show a reading of 100 making it difficult to determine the proximity of a person of unknown size.
[0054] However, the charge transfer of only the small sensor 802 is not as dependent on the size of the person above of the sensor. This is because the area of the sensor is small in relation to the person above the sensor. Unfortunately, however, the small sensor 802 cannot monitor a large area of interest.
[0055] In the embodiment of FIG. 13 , the multiplexer or switch 806 ( FIG. 15 ), for example a single pole double throw analog switch such as the FSA3157 available from Fairchild Semiconductor of South Portland, Me., is used to alternately electrically connect the charge transfer sensor 42 to either the small sensor 802 or to both the large sensor 800 and the small sensor 802 . The microcontroller 32 may then read the proximity value of the small sensor 802 and determine, over the small area, the relative proximity of the object above. Next, the large sensor 800 and the small sensor 802 are electrically connected to the charge transfer sensor 42 and the proximity value of the object of interest will be determined. By correlating this value to the value determined by the small sensor 802 , the range of values of proximity for the large sensor 800 and small sensor 802 together can be determined based upon the present value for the small sensor 802 . Alternatively, rather than using the value of the small sensor 802 to correlate with the value of the large sensor 800 and small sensor 802 together, the value of the large sensor 800 alone could be detected and correlated with the value small sensor 802 to obtain a proximity value over only the large sensor's 800 area.
[0056] Additionally, when sensing the proximity value of the small sensor 802 , it is desirable to electrically connect the large sensor 800 to the ground plane 804 . This is accomplished by using a control line from the microcontroller that controls the switch 806 and connects the peripheral sensor area either ground or part of the sensor. Alternatively, this may also be accomplished by utilizing the frame output of the charge transfer device to make a logic switch after the first reading each time the device is powered up.
[0057] While the embodiment of FIGS. 13 and 14 is shown having a driven shield and a ground plane, it will be appreciated by one of ordinary skill in the art that an embodiment not having the driven shield may also be implemented without departing from the scope of the present invention.
[0058] Referring to FIG. 15 , another embodiment of the present invention provides a visual display for graphically representing a relative proximity value for a sensor or group of sensors. In this embodiment, the sensor array and its associated microcontroller 32 of FIG. 14 (shown in FIG. 15 as reference numeral 900 ) is electrically connected to a reader device 902 , which comprises a circuit board that provides an interface between the sensors and microcontroller 32 and a display device 904 , which in the preferred embodiment is a computer. The reader device 902 preferably connects to the display device 904 via a USB cable 906 . The display device 904 runs a program which continuously reads the digital value of each sensor in the array, and represents those values graphically. The reader device 902 is not required to be a separate unit. Its functionality could be incorporated into either the sensor circuit or the display device 904 .
[0059] Because the sensors are not calibrated, and because the actual digital value for a particular proximity level is influenced by a number of factors (such as sensor size, shape, and material, and mattress or cushion density and thickness), the display device 904 should provide a method of correlating the actual digital values with proximity levels for each sensor, for each particular system. For example, it can provide a table of maximum and minimum values for each sensor. The maximum value is set to the actual digital value that results from a proximity level of infinity (a body in farthest proximity), and the minimum value is set to the actual value that results from a proximity level of zero (a body in nearest proximity). Then, the digital values within the maximum and minimum range are translated and displayed more meaningfully as proximity values. These values are determined and entered manually, or by way of an auto-range mode in the display device. In this mode, it would monitor the digital values for each sensor, and automatically adjust the table entries as it observes new maximum and minimum values, and as a technician provides appropriate near and far stimulus to each sensor.
[0060] While the invention is described above as separate devices used in conjunction with a hospital bed or wheelchair cover, the devices may be integrally formed with the wheelchair cushion or hospital mattress or with the wheelchair or hospital bed without departing from the scope of the present invention.
[0061] Other applications for the proximity sensor would be as a bed/chair occupancy detector to notify hospital or nursing home attendants as to the presence or absence of the patients from a bed or chair. Similarly, it could serve as a toilet seat occupancy device for notifying when a disabled patient has been left on a toilet seat for too long. Moreover, it may be used for car seat occupancy detection to control air bag deployment in a crash. Another application would be for seat occupancy detection on an airplane.
[0062] There are several veterinary applications for the invention as well. For example, before giving birth horses will lay down in their stall. Horse breeders will typically keep a close eye on a horse about to give birth. In order to ease the burden of checking on the horse, a sensor can be placed in the floor of the stall. When the animal lies down, the breeder would be notified by the circuit to attend to the horse. Additionally, it could be used in horse trailers to monitor the horse.
[0063] It could similarly be used on a person as a geriatric fall monitor. The sensor would be placed on the person's body and when proximity with the floor was detected, an alarm for help automatically sounded. Possible locations would be on the person's hip or shoulder.
[0064] Finally, if the conductive layer were placed in close proximity contact with the torso, it could be used to monitor patient vital signs, such as respiration and heartbeat.
[0065] The above examples show that the invention, as defined by the claims, has far ranging application and should not be limited merely to the embodiments shown and described in detail. Instead the invention should be limited only to the explicit words of the claims, and the claims should not be arbitrarily limited to embodiments shown in the specification. The scope of protection is only limited by the scope of the accompanying claims, and the Examiner should examine the claims on that basis.
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An immersion sensor for use with a cushion or mattress for determining the relative immersion of a person within the cushion or mattress comprising a sensor, a ground and a circuit for measuring capacitance. The sensor comprises a sheet of conductive material, and the ground comprises a second sheet of conductive material. The circuit is adapted to send short bursts of electrical current to the sensor and a capacitor. The circuit is further adapted to measure the length of time the burst of current takes to charge the capacitor. Based upon the measured time, the circuit calculates the proximity of the object based upon the time taken to charge the capacitor. A method that may be implemented with the immersion sensor is also disclosed.
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RELATED APPLICATIONS
[0001] This application is a non-provisional application and claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 62/094,788, filed Dec. 19, 2014, which is incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
[0002] The present application pertains to laser-assisted eye surgery using a liquid optical interface and, more particularly, to systems and methods for monitoring and reacting to insufficient liquid within the interface.
BACKGROUND
[0003] A cataract is formed by opacification of the crystalline lens or its envelope—the lens capsule—of the eye. The cataract obstructs passage of light through the lens. A cataract can vary in degree from slight to complete opacity. Early in the development of an age-related cataract, the power of the lens may be increased, causing near-sightedness (myopia). Gradual yellowing and opacification of the lens may reduce the perception of blue colors as those wavelengths are absorbed and scattered within the crystalline lens. Cataract formation typically progresses slowly resulting in progressive vision loss. If left untreated, cataracts may cause blindness.
[0004] A common cataract treatment involves replacing the opaque crystalline lens with an artificial intraocular lens (IOL). Every year, an estimated 15 million cataract surgeries are performed worldwide. Traditionally, cataract surgery has been typically performed using a technique called phacoemulsification in which an ultrasonic tip with associated irrigation and aspiration ports is used to sculpt the relatively hard nucleus of the lens to facilitate removal through an opening made in the anterior lens capsule. Access to the lens nucleus can be provided by performing an anterior capsulotomy in which a small round hole is formed in the anterior side of the lens capsule using a surgical. Access to the lens nucleus can also be provided by performing a manual continuous curvilinear capsulorhexis (CCC) procedure. After removal of the lens nucleus, a synthetic foldable intraocular lens (IOL) can be inserted into the remaining lens capsule of the eye.
[0005] One of the most technically challenging and critical steps in the cataract extraction procedure is providing access to the lens nucleus for removal of the cataract by phacoemulsification. The desired outcome is to provide a smooth continuous circular opening through which phacoemulsification of the nucleus can be performed safely and easily, and also through which an intraocular lens may be easily inserted. Because of the criticality of this step, some surgeons prefer a surgical laser beam over manual tools like microkeratomes and forceps since the laser beam can be focused precisely on extremely small amounts of eye tissue, thereby enhancing the accuracy and reliability of the capsulotomy procedure.
[0006] Several commercial laser-assisted eye surgery systems are available to facilitate cataract removal and astigmatism correction. The CATALYS Precision Laser System from Abbott Medical Optics is indicated for anterior capsulotomy, phacofragmentation, and the creation of single plane and multi-plane arc cuts/incisions in the cornea to correct astigmatism. The CATALYS System uses a two-piece liquid-filled interface that docks with the patient's eye with the liquid providing a transmission medium for the laser, thus avoiding distortion of the eye from contact with an applanation lens. The liquid provides a clear optical path for real-time video, OCT imaging, and laser treatment. Aspects of the CATALYS System are disclosed in U.S. Pat. No. 8,394,084, U.S. Pat. No. 8,500,724, U.S. Pat. No. 8,425,497, U.S. Patent Publication 2014/0163534, U.S. patent application Ser. No. 14/256,307, filed Apr. 18, 2014, and U.S. Patent Publication No. 2014/0343541, filed Apr. 17, 2014, the contents of all of which are incorporated herein by reference as if fully set forth. Other systems for laser cataract surgery are the LenSx Laser from Alcon Laboratories, Inc., the LENSAR Laser System from LENSAR, Inc., and the VICTUS Femtosecond Laser Platform from TECHNOLAS Perfect Vision GmbH a Bausch+Lomb Company.
[0007] The interstitial layer of fluid has a strong influence on the delivery of a high fidelity laser spot in the correct location. One drawback with current systems that use liquid-filled optical interfaces is loss of liquid. Most docking interfaces rely on suction to hold the interface to the eye, and sometimes to hold separate pieces of the interface together. If during a laser procedure the interface shifts so that the liquid-filled chamber comes in fluid communication with the suction in any of these couplings, the level of liquid in the interface may be reduced to be replaced with air which has a different index of refraction and would affect the laser optics. If this happens during laser treatment, it is important to shut off delivery of the laser energy before any mistreatment, or even injury, can occur.
[0008] Accordingly, there is a need for systems that detect loss of liquid in the optical interface.
SUMMARY
[0009] Improved laser eye surgery systems, and related methods, are provided. The laser eye surgery systems use a laser to form precise incisions in the cornea, in the lens capsule, and/or in the crystalline lens nucleus. In a preferred embodiment, a laser eye surgery system includes a laser cutting subsystem to produce a laser pulse treatment beam to incise tissue within the eye. A liquid transmissive media is used between a patient interface lens and the eye to avoid imparting undesirable forces to the patient's eye. The present application provides a number of solutions for monitoring the liquid level within the patient interface.
[0010] One particular embodiment of a liquid monitor includes one or more sensors positioned within the patient interface and in communication with the liquid therein. The sensors may be conductive pads which conduct current therebetween through the liquid until the liquid level drops too low. Alternatively, a light source may be shone down onto the liquid within the patient interface and light refracted through the liquid monitored for changes in the liquid level. Still further, a matched pair of acoustic emitter and sensor may be integrated into the patient interface which produce different signals when the liquid levels are high and low. Another solution is to incorporate an extremely small diameter orifice in the side of the liquid chamber and pull a very low vacuum on the orifice. If the liquid is covering the orifice, surface tension will prevent aspiration of the fluid, but when the liquid level drops air can be pulled through the orifice which is detected by an external sensor in the vacuum line. Finally, a gas flow meter may be installed within a vacuum supply circuit for a suction ring on the patient interface. The gas flow meter detects major suction losses as well as slow leaks by utilizing a sensor of high sensitivity.
INCORPORATION BY REFERENCE
[0011] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
[0013] FIG. 1 is a side view of a patient positioned under a patient interface of a laser-assisted eye surgery system;
[0014] FIG. 2 is a simplified block diagram showing a top level view of the configuration of a laser eye surgery system having a patient interface in accordance with the present application;
[0015] FIGS. 3A-3D are perspective, elevational, plan and sectional views, respectively, of an eye-contacting member of an exemplary patient interface of the present application;
[0016] FIG. 4 is a sectional view through an assembled patient interface with the eye-contacting member docked against an upper member that has an object lens for laser delivery;
[0017] FIGS. 5A and 5B are sectional views through the assembled patient interface taken along a section line perpendicular to that of FIG. 4 and showing a first solution for monitoring a fluid level within the interface comprising conductive pads mounted to an inner wall of the eye-contacting member with the fluid level both high and low, respectively;
[0018] FIGS. 6A and 6B are sectional views through the assembled patient interface showing another solution for monitoring the fluid level including a light source and refracted light position detector integrated into the interface;
[0019] FIGS. 7A and 7B are sectional views through the assembled patient interface showing a still further solution for monitoring the fluid level including a matched pair of acoustic emitter and sensor integrated within the interface;
[0020] FIGS. 8A and 8B are sectional views through the assembled patient interface showing yet another solution for monitoring a fluid level including a small orifice through the wall of the interface connected to a vacuum line; and
[0021] FIG. 9 is a schematic of suction circuits connected to the patient interface and showing a still further solution for monitoring a fluid level within the patient interface.
DETAILED DESCRIPTION
[0022] Methods and systems related to laser eye surgery are disclosed. A laser is used to form precise incisions in the cornea, in the lens capsule, and/or in the crystalline lens nucleus. In a preferred embodiment, a laser eye surgery system includes a laser cutting subsystem to produce a laser pulse treatment beam to incise tissue within the eye, a ranging subsystem to measure the spatial disposition of external and internal structures of the eye in which incisions can be formed, an alignment subsystem, and shared optics operable to scan the treatment beam, a ranging subsystem beam, and/or an alignment beam relative to the laser eye surgery system. The alignment subsystem can include a video subsystem that can be used to, for example, provide images of the eye during docking of the eye to the laser eye surgery system and also provide images of the eye once the docking process is complete. In a preferred embodiment, a liquid interface is used between a patient interface lens and the eye. The use of the liquid interface avoids imparting undesirable forces to the patient's eye.
[0023] Laser System Configuration
[0024] FIG. 1 shows a laser eye surgery system 20 , in accordance with the present application, operable to form precise incisions in the cornea, in the lens capsule, and/or in the crystalline lens nucleus. The system 20 includes a diagnostic and interventional unit 22 under which the patient lies on a patient chair 24 that may be elevated up and down. A patient interface 26 is shown between the eye E of the patient and the diagnostic and interventional unit 22 , the attributes of which will be described below.
[0025] The diagnostic and interventional unit 22 houses a number of subsystems which are not illustrated herein. For example, the unit 22 may provide a touch-screen control panel, patient interface vacuum connections, a docking control keypad, a patient interface radio frequency identification (RFID) reader, external connections (e.g., network, video output, one or more foot switches, USB port, door interlock, and AC power), a laser emission indicator, an emergency laser stop button, key switch, and USB data ports. These subsystems are shown and described in U.S. Patent Publication No. 2014/012821, filed Oct. 31, 2013, the contents of which are expressly incorporated herein by reference.
[0026] The patient chair 24 includes a headrest 28 and a patient chair joystick control 30 for a chair positioning mechanism (internal, not shown). The patient chair 24 is configured to be adjusted and oriented in three axes (x, y, and z) using the patient chair joystick control 30 . The headrest 28 and a restrain system (not shown, e.g., a restraint strap engaging the patient's forehead) stabilize the patient's head during the procedure. The headrest 28 desirably includes an adjustable neck support to provide patient comfort and to reduce patient head movement. The headrest 28 is configured to be vertically adjustable to enable adjustment of the patient head position to provide patient comfort and to accommodate variation in patient head size.
[0027] The patient chair 24 allows for tilt articulation of the patient's legs, torso, and head using manual adjustments. The patient chair 24 accommodates a patient load position, a suction ring capture position, and a patient treat position. In the patient load position, the chair 24 is rotated out from under the diagnostic and interventional unit 22 with the patient chair back in an upright position and patient footrest in a lowered position. In the suction ring capture position, the chair is rotated out from under the diagnostic and interventional unit 22 with the patient chair back in reclined position and patient footrest in raised position. In the patient treat position, the chair is rotated under the diagnostic and interventional unit 22 with the patient chair back in reclined position and patient footrest in raised position.
[0028] FIG. 2 shows a simplified block diagram of the system 20 coupled with a patient eye E. The patient eye E comprises a cornea, a lens, and an iris. The iris defines a pupil of the eye E that may be used for alignment of eye E with system 20 . The system 20 includes a cutting laser subsystem 44 , an OCT imaging system 46 , an alignment guidance system 48 , a video camera 49 , shared optics 50 , the patient interface 26 , control electronics 54 , a control panel/GUI 56 , user interface devices 58 , and communication paths 60 . The control electronics 54 are operatively coupled via the communication paths 60 with the cutting laser subsystem 44 , the OCT imaging system 46 , the alignment guidance subsystem 48 , the video camera 49 , the shared optics 50 , the patient interface 26 , the control panel/GUI 56 , and the user interface devices 58 . Again, further details of these aspects are shown and described in U.S. Patent Publication No. 2014/012821, to Gooding, previously incorporated herein by reference.
[0029] In a preferred embodiment, the cutting laser subsystem 44 incorporates femtosecond (FS) laser technology. By using femtosecond laser technology, a short duration (e.g., approximately 10 −13 seconds in duration) laser pulse (with energy level in the micro joule range) can be delivered to a tightly focused point to disrupt tissue, thereby substantially lowering the energy level required as compared to the level required for ultrasound fragmentation of the lens nucleus and as compared to laser pulses having longer durations. The cutting laser subsystem 44 can produce laser pulses having a wavelength suitable to the configuration of the system 20 . As a non-limiting example, the system 20 can be configured to use a cutting laser subsystem 44 that produces laser pulses having a wavelength from 1020 nm to 1050 nm. For example, the cutting laser subsystem 44 can have a diode-pumped solid-state configuration with a 1030 (+/−5) nm center wavelength.
[0030] Patient Interfaces
[0031] The patient interface 26 is used to restrain the position of the patient's eye E relative to the system 20 . In a preferred embodiment, the patient interface 26 employs a suction ring that attaches to the patient's eye E using a vacuum line. The suction ring is then coupled with the patient interface 26 , for example, using vacuum to secure the suction ring to the patient interface 26 . In a preferred embodiment, the patient interface 26 includes an optically transmissive structure (lens) having a posterior surface that is displaced vertically from the anterior surface of the patient's cornea and a region of a suitable liquid (e.g., a sterile buffered saline solution (BSS)) is disposed between and in contact with the posterior surface and the patient's cornea to form part of a transmission path between the shared optics 50 and the patient's eye E. The optically transmissive structure may comprise a lens 62 (see FIG. 4 ) having one or more curved surfaces. Alternatively, the patient interface 26 may comprise an optically transmissive structure having one or more substantially flat surfaces such as a parallel plate or wedge. In a preferred embodiment, the patient interface lens is disposable and is replaced before each eye treatment.
[0032] FIGS. 3A-3D depict an eye-contacting member 70 of the exemplary patient interface 26 used in the laser eye surgery systems described herein. As mentioned above, an exemplary patient interface 26 incorporates a suction ring 72 for coupling with the eye E, for example, using vacuum. More specifically, a lower or distal end of the patient interface 26 is placed in contact with the cornea of the eye E and suction drawn through a first suction conduit 74 a coupled to the suction ring. The first suction conduit 74 a extends from the suction ring 72 to a plurality of components including a vacuum source, as will be described with reference to FIG. 9 .
[0033] The patient interface 26 comprises a two-part assembly with an upper member 76 (see FIG. 4 ) having features configured to be removably coupled to the diagnostic and interventional unit 22 , such as that described above in reference to FIG. 1 . The upper member 76 is also removably coupled to the eye-contacting member 70 via suction, as will be described. In an exemplary procedure, the patient chair 24 is rotated out from under the diagnostic and interventional unit 22 to the suction ring capture position. A physician or technician can then easily engage the eye-contacting member 70 of the interface 26 to the patient's eyes E using the suction ring 72 . The chair 24 is then rotated to the patient treat position under the diagnostic and interventional unit 22 , and the eye-contacting member 70 and upper member 76 are coupled together, such as shown in FIG. 1 . The system 20 is then ready for a laser-assisted ophthalmic procedure.
[0034] It should be noted that the patient interface 26 may comprise separable components such as the eye-contacting member 70 and upper member 76 , or can be provided together as a single inseparable unit. Further details of exemplary liquid-filled patient interfaces are disclosed in U.S. Patent Publication 2013/0102922, filed Oct. 21, 2011, the contents of which are expressly incorporated herein by reference.
[0035] With reference again to FIGS. 3A-3D , the eye-contacting member 70 of the patient interface 26 in this embodiment comprises a generally frustoconical body 80 having an upper cylindrical rim 82 . The rigid, preferably molded, body 80 has a generally annular cross-section and defines therein a throughbore 84 as seen best in FIG. 3D . A small radially-projecting handle 88 permits a physician or technician to easily manipulate the member 70 , and a trio of fluid conduits 74 a , 74 b and 90 extend radially away in the same direction.
[0036] FIG. 3D best shows an internal structure of the eye-contact member 70 . The body 80 receives an annular elastomeric seal 92 in a circular groove to provide a seal for mating with the upper member 76 . The upper fluid conduit 74 b attaches to a corresponding nipple 94 b having a lumen that is in fluid communication with an annular space 96 defined within two walls of the seal 92 . As is shown in FIG. 4 , a vacuum pulled through the conduit 74 b creates a suction within the seal 92 which pulls a lower surface of the upper member 76 into contact with the seal, thus effectively holding together the two parts of the patient interface 26 .
[0037] On the bottom end of the frustoconical body 80 , the elastomeric suction ring 72 also defines a pair of annular walls (not numbered) that define a space 98 therebetween. The lower fluid conduit 74 a attaches to a corresponding nipple 94 a having a lumen that is in fluid communication with the space 98 . When a vacuum is pulled through the conduit 74 a , the suction ring 72 can be secured to the generally spherical surface of the eye E.
[0038] The assembly of the eye-contacting member 70 coupled to the eye E, with the upper member 76 held by suction to the elastomeric seal 92 , is shown in FIG. 4 . As mentioned above, the upper member 76 mounts within the upper cylindrical rim 82 of the frustoconical body 80 of the eye-contacting member 70 . The upper member 76 includes a generally frustoconical wall 100 having a small circular flange 102 projecting downward therefrom that fits within the annular space 96 ( FIG. 3D ) defined within the two walls of the elastomeric seal 92 . This helps center the two components. A vacuum through the upper fluid conduit 74 b pulls the frustoconical wall 100 against the blades of the elastomeric seal 92 , thus securing the upper member 76 to the eye-contacting member 70 .
[0039] The optical lens 62 is thus held securely centered within the patient interface 26 , and above the eye E. More specifically, the posterior surface of the optical lens 62 is spaced vertically from the anterior surface of the patient's cornea across a region of a suitable liquid 110 (e.g., a sterile buffered saline solution (BSS)) within a transmissive fluid chamber 112 . The chamber 112 includes that portion of the throughbore 84 within the eye-contacting member 70 below the lens 62 and within a conical field of view 114 (shown in dashed line) of the optical instruments of the laser-assisted system described above. However, the chamber 112 also extends outward from the field of view 114 which provides space for the liquid level sensing instruments described herein. Although not shown, inlet and outlet ports to the chamber 112 are provided in the eye-contacting member 70 for supplying and draining liquid as needed, in particular for maintaining a pressure equilibrium.
[0040] Liquid Level Detection Solutions
[0041] FIGS. 5A and 5B are sectional views through the assembled patient interface 26 taken along a section line perpendicular to that of FIG. 4 . A first solution for monitoring the fluid level within the interface 26 comprises a pair of conductive pads 120 mounted to an inner wall of the eye-contacting member 70 , such as diametrically across from one another (of course, the conductors could be mounted at other locations). Circuitry associated with the conducting pads 120 is not shown but would include a current sensor for detecting any current passing between the pads 120 . FIG. 5A shows the liquid 110 filling the chamber 112 . In this configuration, which is preferred for normal laser operation, a current may be passed through the liquid between the conducting pads 120 , thus closing the associated circuit. On the other hand, when the level of the liquid 110 drops in the chamber 112 , as seen in FIG. 5B , an air gap exists between the conducting pads 120 , thus preventing current flow between the pads. Consequently, the current sensor communicates with the control electronics 54 and if the laser is in use, shuts it down. A pair of spaced conducting pads 120 may be mounted at the same level as shown, or two or more pairs and associated circuits may be included to provide indicators for multiple fluid levels. In an alternative configuration, the sensing pads 120 may be calibrated to measure capacitance which is altered when the fluid drops low enough to lose contact with the pads.
[0042] FIGS. 6A and 6B illustrate a second solution for optically monitoring the fluid level within the patient interface 26 . More particularly, a light emitting source 130 is provided within the patient interface 26 or above it so that it shines downward at an angle through the lens 62 and into the liquid 110 in the chamber 112 . When the light from the source 130 hits the surface of the liquid 110 , it refracts as shown. A position detector 132 mounted to the inner wall of the eye-contacting member 70 senses the position of the refractive light. For a high liquid level, as seen in FIG. 6A , the angle of refraction causes the light to hit the position detector 132 relatively high up. On the other hand, when the liquid level drops, as seen in FIG. 6B , the angle of refraction is altered such that the light reaches the position detector 132 lower down, thus indicating an unacceptable loss of liquid. At some point the position detector 132 communicates with the control electronics 54 and if the laser is in use, shuts it down. The light position detector 132 could be either a continuous position detector to sense all fluid levels continuously, or may be constructed with discrete detectors to monitor specific levels (e.g., normal and low).
[0043] FIGS. 7A and 7B illustrate the patient interface 26 with a matched pair of acoustic emitter 140 and sensor 142 integrated therein. In particular, the emitter 140 and sensor 142 are mounted to the inner wall of the frustoconical body 80 diametrically across from one another. When the liquid 110 is at a high level in the chamber 112 , acoustic signals from the emitter 140 are received by the sensor 142 through the fluid therebetween. After the liquid level drops, as seen in FIG. 7B , the sound waves from the emitter 140 take on a much different character passing through the air gap to the sensor 142 . Fluid loss may also be detected by the changing character of the acoustic signature induced by a changing fluid volume, even before the level of the liquid descends below either the emitter 140 or the sensor 142 . The emitter 140 and sensor 142 may be integrated into the frustoconical body 80 of the eye-contact member 70 , or may be provided as separate components either mounted to the body or introduced into the liquid 110 from above.
[0044] FIGS. 8A and 8B shows the patient interface 26 having a small orifice 150 through the wall of the body 80 . A nipple (not numbered) leading from the orifice 150 connects to a vacuum line 152 . A slight vacuum can be applied through the vacuum line 152 and thus to the orifice 150 . When the orifice 150 is covered by fluid, such as seen in FIG. 8A , surface tension will prevent the fluid from passing through the orifice, which results in a full vacuum. The magnitude of the vacuum pressure is sensed and a full vacuum means there is sufficient fluid in the chamber 112 . Alternatively, when the level of the liquid 110 drops below the orifice 150 , the slight vacuum will pull any residual fluid and air through the orifice 150 , thus significantly lowering the magnitude of the vacuum or negative pressure from loss of resistance. If the laser is operating it is then shut off. The diameter of the orifice 150 is extremely small such that surface tension of the liquid prevents aspiration through the orifice when a low vacuum is applied, but allows free flow of air when the fluid level drops below the orifice. A number of orifices 150 can be provided in various positions around the body 80 to reduce false-negative conditions and/or provide sensing at multiple fluid levels.
[0045] Finally, an indirect method for monitoring the fluid level 110 within the patient interface may be incorporated into the patient interface suction system. FIG. 9 is a schematic of suction circuits connected to the patient interface 26 , and illustrates the eye E below the patient interface including the upper member 76 and eye-contacting member 70 .
[0046] The patient interface 26 couples to the first suction conduit 74 a and second suction conduit 74 b . The first suction conduit 74 a extends from the suction ring 72 (see FIG. 4 ) to a vacuum source such as an eye retention structure vacuum pump 200 . The suction conduit 74 a couples the first fluid collector 202 to the patient interface 26 to receive fluid therefrom. A first fluid stop 204 couples to an outlet of the first collector 202 and includes a float valve or porous structure to pass a gas such as air and inhibit flow of a liquid or viscous material so as to stop substantially the flow of the liquid or viscous. A suction vacuum regulator 206 along first suction conduit 74 a provides a regulated amount of pressure to eye E with the suction ring, for example suction pressure between about 300 and 500 mm Hg (millimeters Mercury), for example. The outlet of the suction vacuum regulator 206 is coupled to the vacuum pump 200 which is coupled to control electronics 54 with communication paths 60 .
[0047] The second suction conduit 74 b extends from the patient interface 26 to a vacuum source such as dock vacuum pump 210 . The second suction conduit 74 b provides suction to the interface between the upper member 76 and the eye-contacting member 70 , and clamps the two together. Suction conduit 74 b extends to a second fluid collector 212 and then to a second fluid stop 214 which contains a porous structure or float valve to inhibit flow of a liquid or viscous material and substantially stop the flow therethrough. The components within dashed area 216 form a liquid optics interface (LOI). The second fluid stop 214 couples to a dock monitor 215 , which can be positioned along second suction conduit 74 b in order to monitor suction for coupling upper member 76 to eye-contacting member 70 . Suction monitor 215 comprising a pressure sensor is positioned along the second suction conduit 74 b downstream of the second fluid stop 214 and a dock solenoid valve 216 . The pressure sensor 215 can be coupled to control electronics 54 via the communication paths 60 , as described herein. The pressure sensor 215 preferably comprises a transducer responsive to pressure of the suction conduit 74 b . The suction solenoid valve 216 is coupled to control electronics 54 , and the second suction conduit 74 b may include another suction line monitor 217 to monitor suction downstream of suction solenoid valve 216 . The suction line monitor 217 preferably couples to an inlet of the vacuum pump 210 , which is also connected to the control electronics 54 .
[0048] The third conduit 90 connected to the patient interface 26 (see FIG. 4 ) leads to a suction monitor 220 and then to a suction solenoid valve 222 . The suction monitor 220 keeps track of the section level within the suction ring 72 and is coupled to control electronics 54 via the communication paths 60 .
[0049] To indirectly sense liquid loss, a flow sensor 230 is introduced in the first suction conduit 74 a in series between a suction solenoid valve 232 and the vacuum regulator 206 . The flow sensor 230 , which may be a gas flow meter, monitors gas flow within the first suction conduit 74 a , and provides an alternative method for detecting major suction loss as well as slow leaks by utilizing a sensor of high sensitivity. A loss of liquid in the patient interface 26 may be caused by displacement between the interface and the patient's eye, which suddenly alters the gas flow into the suction ring 72 . That is, when the suction ring 72 is engaged with the eye there is very little gas flow, while a disconnect suddenly allows air to be sucked into the suction conduit 74 a . This can be sensed by the flow sensor 230 which is in communication with control electronics 54 which may shut the system down if the laser is operational. A high enough flow sensitivity also will detect small leaks which could ultimately lead to a major liquid loss.
[0050] The coupling lines as described herein may comprise lines for fluidic coupling known to a person of ordinary skill in the art and may comprise one or more of tubing, flexible tubing, rigid tubing, plastic tubing, metal tubing or manifolds, for example. The containers as described herein may comprise similar materials and can be constructed by a person of ordinary skill in the art based on the teachings provided herein.
[0051] A preferred laser cataract surgery using the aforementioned system is done by connecting the patient's eye with the laser system via a liquid-filled patient interface. The lower part of the patient interface attaches to the patient's eye by applying a vacuum over a ring-shaped area. The patient interface is then filled with a suitable sterile liquid (e.g., a sterile buffered saline solution (BSS)) interior to this ring, so that the sterile liquid is in direct contact with the patient's cornea. The patient is then moved with the chair to a position where the top part of the patient interface can be attached to an overhanging laser system by pulling vacuum over a second area, also with the shape of a ring. The sterile liquid is also in direct contact with the laser system's optics and the becomes part of the optical system of the instrument, interfacing the optical hardware with the patient's eye.
[0052] During treatment, the laser energy is transmitted into the patient's eye thought the sterile liquid contained in the patient interface. Precise positioning of the laser beam in the human eye is very important and the system optics, interface liquid and eye media are taken into consideration by the system software.
[0053] If during treatment, the liquid level within the interface to the patient were to decrease, the optics for the laser would be affected because air has a smaller index of refraction, perhaps causing harm to the patient. This situation could be caused by patient movement displacing the patient interface components such that sterile liquid enters the various vacuum conduits. Thus, the various techniques for detecting liquid loss within the patient interface 26 alert the physician/technician or system electronics to a possible catastrophic situation and corrective action can be quickly taken.
[0054] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
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A laser eye surgery system that has a patient interface between the eye and the laser system relying on suction to hold the interface to the eye, the patient interface using liquid used as a transmission medium for the laser. During a laser procedure sensors monitor the level of liquid within the patient interface and send a signal to control electronics if the level drops below a threshold value. The sensor may be mounted on the inside of the patient interface, within a fluid chamber. Alternatively, a gas flow meter may be added to a suction circuit for the patient interface that detects abnormal suction levels indicating low fluid level.
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FIELD OF THE INVENTION
The invention relates to a process of manufacturing a EVOH/Polyester (coextruded) bistretched film. The invention also relates to such a film, showing high barrier properties and high mechanical properties.
BACKGROUND OF THE INVENTION
Extrusion of multilayer films is well-known. Stretching of films, being monolayer or multilayer films, is known as well.
The above techniques have been applied to many different types of films, in order to obtain the desired results. One multilayer film that would be of high interest is a film containing a layer of EVOH and a layer of polyester. The layer of EVOH would impart barrier properties such as gas barrier properties against oxygen, carbon dioxide, helium, aroma and flavors, etc. . . . The layer of polyester would impart mechanical properties, such as Young's modulus, tensile strength, heat resistance, clarity, etc. . . . Since these two types of polymers are not compatible, a coextrusion binder is necessary. Thus, one would look for films having one layer of EVOH, one layer of coextrusion binder and one layer of polyester.
The process of manufacturing such films is, however, very delicate. Especially, stretched films are very difficult to manufacture, since the layer of EVOH is very difficult to stretch, especially to bistretch. As a matter of fact, polyester, being nearly amorphous at the exit of the extruder, can be easily stretched, either simultaneously or sequentially, and high quality film is easily obtained. The EVOH layer on the contrary, has a high tendency to crystalise under heat and stress, so that a sequential stretching is not possible: stretching in MD direction forms a crystalline EVOH layer, that breaks whilst the attempt to stretch in TD direction. Simultaneous stretching is thus required. Eventually, the stretched films are heat set, so as to develop the mechanical properties of the film, thanks to the polyester layer.
Thus, there is a need for a method that would allow the production of valuable multilayer EVOH/PET films, but would also be cost effective and easy to carry out.
JP-A-55139263 discloses a process where a multilayer film is bistretched then heat treated at a temperature below the melting point of the EVOH material. This, however, is not satisfactory, since the melting point of all EVOH grades suitable for high barrier applications is below 190° C., preferably below 180° C., most preferably below 170° C. Such low heat-set temperatures are not appropriate to maintain the thermo-mechanical strength of the outer polyester layers, resulting from the biaxial stretching. This would lead to a high thermal shrinkage and the high mechanical strength of polyester film would be lost at higher temperatures.
JP-A-63272548 discloses a process for manufacturing a laminate stretched film comprising coextruding a 5-layer film, especially polyester/binder/EVOH/binder/polyester, simultaneously bistretching it, and heat-treating it under the following conditions:
0.5≦X≦5
EVOH melting point+40° C.≦T≦polyester melting point 8 sec≦t≦25 sec
where:
X=total polyester thickness/EVOH thickness
T=heat treatment temperature
t=heat treatment time
Examples given in this document provide simultaneous bistretching at a temperature of 90° C., at ratios of 3.3×3.3, followed by heat treatment at a temperature of about 230° C., for a duration of about 15 sec. The respective polymers are PET, EVOH and modified PET or modified EVA resin as a binder. The thicknesses (unstretched/stretched) of the EVOH and PET layers are respectively about 54 μm/5 μm and about 130 μm/12 μm, giving a X value of about 2.5. The EVOH melting point is about 180 (leading to on heatset temperature of 220° C. for EVOH mp+40° C.) while PET melting point is about 260° C. At this high heatset temperatures, the film starts to crystallize and gets brittle very fast. Heatset times higher than 8 seconds will definitely lead to film breakage in the oven and a loss of mechanical properties, especially elongation, due to high crystallization and brittleness thereof. Additionally, running a film line with such high hold-up times in the heatset zones would require either very long heatset zones in the oven or very low line speeds. This is economically not suitable for such a product.
SUMMARY OF THE INVENTION
The object of the present invention is a process where the heat treatment is carried out during a time below 8 sec., and at a temperature preferably below 220° C.
The resulting film shows enhanced properties, especially when the ratio of thicknesses of polyester to EVOH is higher than 5.
DETAILED DESCRIPTION OF THE INVENTION
The polyester used in the invention is any polyester where the major part of it is comprised of any aromatic repeating ester units. The term polyester in this invention refers to a polymer that is obtained by condensation polymerization of an aromatic dicarboxylic acid such as terephthalic acid or 2,6-naphthalene dicarboxylic acid and of an aliphatic glycol such as ethylene glycol, 1,4-butanediol or 1,4-cyclohexane dimethanol. These polymers, in addition to being homopolymers, may also be copolymers having a third component or several components. In this case, the dicarboxylic acid component may be, for example, isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4′-diphenyldicarboxylic acid, adipic acid, sebacic acid, decanedicarboxylic acid and 1,4-cyclohexane dicarboyxlic acid; the oxycarboxylic acid component can be, for example, p-oxybenzoic acid and the glycol component can be, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, neopentyl glycol, 1,4-cyclohexane dimethanol, polyethylene glycol and polytetramethylene glycol.
Examples of such polyesters are polyethylenenaphthalate (PEN), polybutyleneterephthalate (PBT), polyethyleneterephthalate (PET), the latter PET being the preferred polyester.
Mixtures are also possible, optionally with another polymer different from a polyester. The intrinsic viscosity of the polyester that is used in the invention may vary from e.g. 0.45 to e.g. 0.7, measured in phenoltetrachloreethane at 30° C. The MW may vary within broad limits, e.g. between 10000 to 30000 g/mol.
The binder material is any material that is adhesive and allow the polyester and EVOH layers to show adhesion, with either adhesive rupture or cohesive rupture. The skilled man will choose the binder thanks to its general knowledge or thanks to routine tests.
Examples of such binders include modified polyolefins, polyacrylates, polyurethanes, polyesters, etc.
Examples of binders are the following (co)polymers, grafted with maleic anhydride or glycidyl methacrylate, in which the grafting rate is for example from 0.01 to 5% by weight:
PE, PP, copolymers of ethylene with propylene, butene, hexene, octene, butadiene, EPR, EPDM, containing, for example, 35 to 80% by weight ethylene, as well as any styrene-based block copolymers such as SBS, SIS, SEBS, and the like;
ethylene and vinyl acetate (EVA) copolymers containing up to 40% by weight vinyl acetate;
ethylene and alkyl (meth)acrylate copolymers containing up to 40% by weight alkyl(meth)acrylate;
ethylene and vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight comonomers.
Further examples of binders are the following (co)polymers, in which ethylene represents preferably at least 60% by weight and where the termonomer represents, for example, 0.1 to 10% by weight of the copolymer:
ethylene/alkyl (meth)acrylate or methacrylic acid/maleic anhydride or glycidyl methacrylate copolymers;
ethylene/vinyl acetate/maleic anhydride or iglycidyl methacrylate copolymers;
ethylene/vinyl acetate/alkyl (meth)acrylate or methacrylic acid/maleic anhydride or glydicyl methacrylate copolymers. The term “alkyl (meth)acrylate” stands for C1 to C6 alkyl, such as methyl, ethyl, butyl and 2-ethylhexyl methacrylates and acrylates. Moreover, these polyolefins can also be cross-linked using any suitable process or agent (di-epoxy diacid, peroxy, etc.)
Still further examples of binders include
grafted copolymers constituted by at least one monoamino oligomer of polyamide and of an alpha-mono-olefin (co)polymer grafted with a monomer able to react with the amino functions of said oligomer;
Mixtures thereof are also envisaged. The molecular weight of these binders can also vary greatly, as those skilled in the art will understand.
Examples of such binder compositions are provided in the following patents, this list not being exclusive:
FR-A-2,291,225, FR-A-2,132,780, EP-A-0,210,307, EP-A-0,033,220, EP-A-0,266,994, EP-A-0,171,777, EP-A-0,342,066, EP-A-0,218,665, U.S. Pat. No. -4,758,477, U.S. Pat. No. -4,762,890, U.S. Pat. No. -4,966,810, U.S. Pat. No. -4,452,942, U.S. Pat. No. -3,658,948, U.S. Pat. No. -5,217,812, all of which being incorporated herein by reference.
A prefered binder is an anhydride-modified ethylene vinyl acetate copolymer.
The term “EVOH” as used in the instant invention aims at designing ethylene/vinyl alcohol copolymers containing for example from 15 to 80, preferably 20 to 50 mol % of ethylene. A preferred EVOH contains more than 30 mol %, especially more than 40 mol % of ethylene. This kind of copolymer is well-known in the art, and can be obtained, for example, by saponification of an ethylene/vinyl acetate copolymer, with a saponification degree of generally more than 90%, most preferably more than 95%. A third monomer can be present, in an amount not adversely hindering the barrier porperties. It is permissible to blend other components keeping within a range of not adversely hindering the barrier properties. The blending component should preferably be not more than 40 weight %, more preferably not more than 30 weight %, most particularly not more than 20 weight %.
Such blending resins, for example, include the above ethylene-vinyl alcohol copolymers having an ethylene content different from those which are used as main components, or ethylene-vinyl alcohol copolymers having an ethylene content greater than those which are used as main components, or their partially saponified products, polyamide type polymers, polyester type polymers, ethylene-vinyl ester copolymers, ethylene-aliphatic unsaturated aliphatic acid copolymers, ethylene-aliphatic unsaturated aliphatic acid ester copolymers, ionomer resins, styrene-conjugated diene block copolymers, a partially hydrogenated product of said block copolymer, or else these polymers which have been modified, for example, by grafting a monomer having a carboxylic acid group as a polar functional group, copolymers of ethylene and carbon monoxide, or additionally with the vinyl acetate component or a resin wherein at least some of the acetate groups have been converted into hydroxyl groups, and ethylene, propylene resins, and the like, other that those mentioned above; at least one from these should be used.
Various additives, such as UV-agents, stabilizers, sliding agents, antioxidants, fillers, etc. can be added to each component of the layer, in classical amounts.
The coextrusion referred to in the instant invention is any classical extrusion. The extrusion may be of the type T-die, with feeding block, of the blow film type, etc. Also encompassed in the invention is the extrusion, where individual films are produced, which are then laminated on each other so as to build up a raw multilayer film. In fact, any method that produces a raw film is appropriate; preferably this method is coextrusion.
The extrusion temperature of the EVOH may optimized to reach high barrier properties; said temperature may generally be lower than 220° C., preferably between about 180 and 210° C.
The biaxial stretching or bistretching is carried out simultaneously. It includes stretch ratios of 2 to 5, especially 2.5 to 4, in each direction. The ratio MD stretch ratio/TD stretch ratio is generally comprised between 0.5 to 2, especially 0.7 to 1.3. The suitable stretching temperature is comprised between 75 and 130° C., generally about 90° C. The raw film to e stretched can be preheated, if necessary. Preheat temperature can be as high as the stretching temperature; for example preheat can be performed at a temperature of 80° C. (for about 10 sec) while stretching is carried out at a temperature of 90° C. Any simultaneous stretching apparatus can be used; preferably polyester stretching apparatuses are used. Examples of simultaneous bistretching apparatus are disclosed in the following US patents, all incorporated herein by reference: U.S. Pat. Nos. 4,675,582; 4,825,111; 4,853,602; 4,922,142; 5,036,262; 5,051,225; 5,072,493 and 5,416,959.
The heat treatment (or heatsetting) referred to in the instant invention is the classical heat treatment carried out for polyesters; classical apparatuses are used like introducing hot air or using infrared lamps, etc. Either “heatset” or “heat treatment” is used in the instant invention, without any distinction.
The raw film shows a total thickness generally between about 10 and 1000 μm, especially between about 50 and 500 μm. The thickness of the polyester layer (total) is generally between about 20 and 950 μm, preferably between 50 and 300 μ. The thickness of the EVOH layer is generally between about 5 and 100 μm, preferably between 10 and 70 μm. The thickness of the binder layer (total) is generally between about 3 and 30 μm, preferably below 10 μm. The ratio thickness of polyester (total) to thickness of EVOH can vary within broad limits; generally, this ratio is above 1, preferably above 5. The resulting bistretched film shows a thickness generally between about 5 and 200 μm, especially between about 10 and 100 μm. Each layer, polyester, EVOH, binder is present according to relative thicknesses as given above with respect to the raw film. For example, the EVOH layer may have a thickness between 1 and 10 μm.
The instant film formed of the various layers can be of various structures and the polyester used can vary from one layer to another. For example, one layer can be obtained from starting products containing scrap material, allowing recycling. Content of scrap is variable within broad limits known to the skilled man. Also, the polyester can have a different nature from one layer to another, or they can be the same. All polyester layers can be comprised of crystalline polyester, or all layer can be comprised of amorphous copolyester, or one layer can be crystalline and the other(s) can be amorphous. For example, the invention provides 5-layer films where one layer is crystalline (i.e. PET) while the other layer is amorphous (i.e. copolyester) This allows to combine specific mechanical properties of crystalline polyester and adhesive properties of the copolyester. It can also be forseen that each layer may be formed of two or more sub-layers; e.g. the outer polyester layer can be formed of one sub-layer of PET and one sub-layer of copolyester, the first one being in contact with the binder layer. The instant films can be used as individual layers in further multilayer films.
The following examples further illustrate the present invention, but do not limit the scope thereof.
EXAMPLES
EVOH:
EVOH polymer was delivered by Kuraray Eval Europe GmbH Duesseldorf.
Grade E105U, 44 mol % ethylene content, density 1.14 g/cm 3 , melt flow index 5.5 g/10 min., melt point 165° C.
BINDER (Bynel)
The binder is an anhydride-modified ethylene vinyl acetate copolymer.
Density 0.95 g/cm 3 , melt index 10.9 g/lomin, melt point 165° C.
PET:
IV: 0.56 dl/g, melt point 256° C.
The polyester polymer was extruded at a temperature of 280° C., the binder polymer at 240° C. The EVOH barrier polymer was extruded at different temperatures (230° C., 205° C. and 175° C.). Die temperature was at 290° C.
The cast film samples are summarised in table 1. The thickness of the different layers was confirmed via microtome-cuts under the microscope.
TABLE 1
Cast film samples
EVOH
PET
Bynel
EVOH
Bynel
PET
Extr. Temp.
Sample
μm
μm
μm
μm
μm
° C.
A
50
<10
50
<10
50
230
B
55
<10
40
<10
55
230
C
60
<10
30
<10
60
230
D
65
<10
20
<10
65
230
E
70
<10
10
<10
70
230
F
70
<10
10
<10
70
205
G
70
<10
10
<10
70
175
The cast films were cut into pieces of 11.2 cm×11.2 cm, preheated at 80-90° C. for 10 sec and simultaneously stretched at 90° C. at a stretch ratio of 3.3×3.3 in 2.2 sec.
The stretched samples were chucked into a frame for preheating at 170° C., 200° C. and 230° C. for 3, 8, 15 and 20 seconds. The resulting stretched films are summarised in table 2.
TABLE 2
Simultaneously stretched films
Preheat
Strech
Heatset
Heatset
Roll
Temp.
Temp.
Stretch
Temp.
Time
No.
[° C.]
[° C.]
Ratio
[° C.]
[sec]
1
80
90
3.3 × 3.3
230
20
2
80
90
3.3 × 3.3
230
20
3
80
90
3.3 × 3.3
230
15
4
80
90
3.3 × 3.3
230
15
5
80
90
3.3 × 3.3
230
8
6
80
90
3.3 × 3.3
230
e
7
80
90
3.3 × 3.3
230
3
8
80
90
3.3 × 3.3
230
3
9
80
90
3.3 × 3.3
200
20
10
80
90
3.3 × 3.3
200
20
11
80
90
3.3 × 3.3
200
15
12
80
90
3.3 × 3.3
200
15
13
80
90
3.3 × 3.3
200
8
14
80
90
3.3 × 3.3
200
8
15
80
90
3.3 × 3.3
200
3
16
80
90
3.3 × 3.3
200
3
17
80
90
3.3 × 3.3
170
20
18
80
90
3.3 × 3.3
170
20
19
80
90
3.3 × 3.3
170
15
20
80
90
3.3 × 3.3
170
15
21
80
90
3.3 × 3.3
170
8
22
80
90
3.3 × 3.3
170
8
23
80
90
3.3 × 3.3
170
3
24
80
90
3.3 × 3.3
170
3
This is stretch and heatset pattern was applied for film samples D, E, F and G.
To evaluate the influence of the thickness of the EVOH layer on the oxygen barrier, samples A-G were stretched under the same conditions (see above) and heatset at 200° C. for 8 sec.
The oxygen barrier was determined with an Ox-tran twin tester. The following table 2 provides the results.
TABLE 3
Oxygen barrier of the film samples
Film
EVOH
EVOH
Oxygen
Thickness
Thickness
Extrusion
Barrier
Sample
[μm]
[μm]
Temp.
cc/m 2 /d
A
15
5
230° C.
5.1
B
14
4
230° C.
7.5
C
15
3
230° C.
10.2
D
14
2
230° C.
13.3
E
14
1
230° C.
21.6
F
13
1
205° C.
6.6
G
13
1
175° C.
7.3
As expected, the oxygen permeability in increasing from 5 to 21 cc/m 2 /d with the decreasing thickness of the EVOH barrier layer from 5 to 1 μm. But also the extrusion temperature of the EVOH polymer has a strong influence on the oxygen barrier. By decreasing the extrusion temperature from 230° C. 205° C. the oxygen permeability drops from 21 to 6.6 cc/m 2 /d. According to these results, a 5 μm EVOH layer extruded at 230° C. to offers the same oxygen barrier than a 1 μm EVOH layer extruded at 205° C.
Samples D-G were examined more intensively regarding the influence of heatset time and temperature. The results of the oxygen barrier are summarised in table 4.
TABLE 4
Oxygen barrier (expressed in cc/m 2 /d) for samples D-
G at different heatset conditions (see table 2)
Roll N°
Sample D
Sample E
Sample F
Sample G
1
15.1
25.7
6.2
9.3
3
17.5
26.3
5.3
9.2
5
14.1
27.4
6.6
7.8
7
16.6
28.0
nd
8.9
9
16.2
25.6
5.9
9.5
11
17.0
26.8
5.7
10.0
13
14.5
27.4
5.7
8.2
15
15.0
24.5
5.5
8.9
17
18.1
25.7
6.3
8.5
19
20.5
28.4
5.9
7.2
21
16.5
21.6
5.7
7.2
23
14.5
23.2
7.3
8.5
nd: not determined
Like in table 3, the oxygen permeability is increasing with decreasing EVOH layer thickness and decreasing with lower EVOH extrusion temperature.
However, it can be said that there is no dependence of the oxygen barrier on heatset time and temperature. High oxygen barrier properties may however be obtained with a lower EVOH extrusion temperature, such as about 205° C.
Mechanical properties, i.e. modulus, tensile strength, force at 3% elongation (F3), force at 5% elongation (F5) and elongation at break, along the MD (machine direction) and the TD (transverse direction) were determined with an Instron equipment at room temperature.
For samples A-G, the mechanical properties at heatset conditions of 200° C. and during 8 sec, are listed on the following table 5.
For samples D-G, the mechanical properties at all heatset conditions (see table 3), are listed on the following pages on table 6-9.
TABLE 5
Mechanical properties of samples A-G
Modulus [N/mm 2 ]
F3 [N/mm 2 ]
F5 [N/mm 2 ]
Tensile [N/mm 2 ]
Elongation [%]
Sample
MD
TD
MD
TD
MD
TD
MD
TD
MD
TD
A
3610
3563
83
81
97
95
174
166
111
116
(15 μm)
B
3768
3770
87
86
101
100
182
181
105
117
(14 μm)
C
3934
3783
90
86
105
102
204
203
110
130
(15 μm)
D
3862
3731
90
86
105
103
205
190
113
122
(14 μm)
E
4032
3809
92
89
109
105
201
209
97
131
(15 μm)
F
3690
3620
84
83
96
95
162
150
112
96
(13 μm)
G
3741
3726
85
85
98
99
170
154
94
84
(13 μm)
TABLE 6
Mechanical Property Data Sample D (Thickness = 14 μm)
Modulus
Modulus
F3
F3
F5
F5
Tensile
Tensile
Elongation
Elongation
MD
TD
MD
TD
MD
TD
MD
TD
MD
TD
Roll N o
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[%]
[%]
1
3981
4140
87
87
93
93
172
173
127
116
3
4005
4064
87
88
95
97
181
184
117
114
5
4099
4229
87
87
95
94
183
177
109
114
7
4099
4363
86
92
95
101
181
194
106
106
9
3896
4025
86
88
97
97
190
188
106
122
11
3935
3986
85
85
93
93
179
172
110
109
13
4116
4276
88
89
96
97
200
173
121
101
15
4120
4208
89
89
98
98
195
192
111
114
17
4158
3849
89
85
100
95
200
201
110
126
19
4145
4156
89
88
100
99
203
203
114
118
21
4051
4074
88
89
98
99
219
208
126
114
23
3967
4251
87
93
96
103
212
227
121
118
TABLE 7
Mechanical Property Data Sample E (Thickness = 14 μm)
Modulus
Modulus
F3
F3
F5
F5
Tensile
Tensile
Elongation
Elongation
MD
TD
MD
TD
MD
TD
MD
TD
MD
TD
Roll N o
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[%]
[%]
1
4541
4770
92
91
99
103
179
193
106
104
3
4316
4497
92
94
102
103
201
207
118
110
5
4655
4712
97
96
104
104
200
209
107
112
7
4488
4508
94
94
102
102
183
198
86
107
9
4528
4420
95
94
104
103
207
208
113
116
11
4307
4393
91
92
100
103
198
208
106
121
13
4421
4344
92
91
101
99
202
192
121
116
15
4173
4521
89
94
98
104
205
209
129
111
17
4316
4357
94
94
105
107
212
229
116
116
19
4186
4269
91
92
101
103
206
196
116
116
21
4136
4023
87
89
97
100
197
213
102
120
23
4171
4082
92
90
102
100
207
203
115
119
TABLE 8
Mechanical Property Data Sample E (Thickness = 13 μm)
Modulus
Modulus
F3
F3
F5
F5
Tensile
Tensile
Elongation
Elongation
MD
TD
MD
TD
MD
TD
MD
TD
MD
TD
Roll N o
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[%]
[%]
1
3416
3688
73
77
78
82
139
155
113
118
3
3742
3388
78
73
82
76
143
133
109
124
5
3603
3334
75
73
78
77
143
123
109
116
7
3211
3516
71
75
75
79
118
130
98
76
9
3247
3580
71
77
77
83
142
145
103
106
11
3577
3476
77
74
83
80
148
135
99
88
13
3199
3608
71
77
76
83
140
147
118
91
15
3216
3590
71
77
76
84
140
141
111
82
17
3799
3729
78
84
78
86
193
190
113
107
19
3745
3619
79
82
85
82
183
183
107
117
21
3655
3609
77
76
83
82
188
178
107
95
23
3436
3294
75
72
82
77
151
144
102
125
TABLE 9
Mechanical Property Data Sample E (Thickness = 13 μm)
Modulus
Modulus
F3
F3
F5
F5
Tensile
Tensile
Elongation
Elongation
MD
TD
MD
TD
MD
TD
MD
TD
MD
TD
Roll N o
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[N/mm 2 ]
[%]
[%]
1
3818
3971
82
85
89
92
163
173
123
119
3
3996
3868
84
83
91
89
165
159
113
107
5
3891
3853
82
82
88
88
163
157
109
105
7
3710
4008
81
84
87
82
159
162
115
87
9
3614
3926
80
84
87
93
154
168
105
93
11
3577
3845
80
84
88
92
154
167
106
107
13
3653
3748
80
82
88
89
162
155
118
105
15
3674
3803
80
82
88
89
151
161
99
97
17
3898
3831
83
81
91
89
205
186
120
100
19
3560
3530
79
78
87
85
155
157
107
120
21
3677
3677
79
79
86
86
187
194
122
133
23
3425
3536
76
79
82
85
153
153
115
103
From the above results, it can be concluded, that a heatset time between 3 and 8 seconds is best suited to obtain a stabilised polyester barrier film with useful mechanical properties and a high oxygen barrier.
It can also be concluded that the invention allows processing of EVOH copolymer with high ethylene content while still obtaining very good barried (oxygen barrier) properties; this is surprising since it is generally admitted that high ethylene content and high barrier property are antinomic.
The invention was described with reference to a preferred embodiment. However, many variations are possible within the scope of the invention.
|
A multilayer film is formed by coextruding and bistretching EVOH, binder and polyester followed by heat treating for less than 8 seconds at a temperature between 170° C. and 250° C.
| 1
|
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2013-91632 filed Apr. 24, 2013 the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a pressure measuring device, comprising: a tube capable of being fixed to a sample body along a surface thereof; a pressure sensor fixed inside the tube; a pipe for supplying reference pressure to the pressure sensor; a closing plug fixed inside the tube to have a predetermined gap from the pressure sensor; a space defined between the pressure sensor and the closing plug inside the tube; and a pressure detecting hole penetrating the tube to communicate with the space, in which unsteady pressure on the surface of the sample body is measured by transmitting the unsteady pressure to the pressure sensor through the pressure detecting hole and the space. In addition, the present invention also relates to a pressure measuring method using the pressure measuring device and a leakage inspecting device for inspecting leakage of the tube of the pressure measuring device.
[0004] 2. Description of the Related Art
[0005] Japanese Patent Application Laid-open No. 62-35235 has made known a technique of measuring distribution of pressure on a surface of a vehicle body of an automobile by: forming through-holes inside a plate-shaped member attached to the surface of the vehicle body, each through-hole having one end opened at an upper surface of the plate-shape member and the other end opened at a peripheral edge portion of the plate-shaped member; and connecting the through-hole opened at the peripheral edge portion of the plate-shaped member to a pressure measuring unit through a pressure output member.
[0006] Moreover, Japanese Patent Application Laid-open No. 2009-25314 has made known a technique of measuring temperature of and pressure on a surface of a body of an airplane by: housing sensors, circuits, a battery, and the like inside a flexible substrate bonded to the surface of the body; and communicating the sensors with ambient air through ports provided in the flexible substrate.
SUMMARY OF THE INVENTION
[0007] Meanwhile, according to the technique described in Japanese Patent Application Laid-open No. 62-35235, pressure sensors are provided outside the plate-shaped member, and the openings at the upper surface of the plate-shaped members and the pressure sensors are connected to each other through the long through-holes formed inside the plate-shaped member. Thus, the technique is capable of measuring the distribution of steady pressure on the surface of the vehicle body. However, in a case of measuring unsteady and subtle pressure fluctuations on the surface of the vehicle body, the pressure fluctuations are made unclear through the long through-holes, thereby causing a problem of being unable to obtain sufficient measurement accuracy.
[0008] Moreover, according to the technique described in Japanese Patent Application Laid-open No. 2009-25314, the sensors are provided near the ports opened in the flexible board. Thus, the problem that unsteady pressure fluctuations on the surface of the body are made unclear does not exist. However, air in a space between each port and its corresponding sensor vibrates due to Helmholtz resonance, and the resultant pressure fluctuations are superposed on the pressure fluctuations on the surface of the body to be measured, thereby causing a problem of deteriorating the measurement accuracy. In addition, in the case of the above technique, reference pressure, which serves as a reference, cannot be inputted to the sensor, and only absolute pressure can be measured, thereby causing a problem of low measurement accuracy.
[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a pressure measuring device capable of accurately measuring unsteady and subtle pressure fluctuations on a surface of a sample body.
[0010] In order to achieve the object, according to a first feature of the present invention, there is provided a pressure measuring device, comprising: a tube capable of being fixed to a sample body along a surface thereof; a pressure sensor fixed inside the tube; a pipe for supplying reference pressure to the pressure sensor; a closing plug fixed inside the tube to have a predetermined gap from the pressure sensor; a space defined between the pressure sensor and the closing plug inside the tube; and a pressure detecting hole penetrating the tube to communicate with the space, in which unsteady pressure on the surface of the sample body is measured by transmitting the unsteady pressure to the pressure sensor through the pressure detecting hole and the space, wherein a volume of the space is set such that a Helmholtz resonance frequency of the space lies outside frequencies of fluctuations of the unsteady pressure.
[0011] According to the first feature of the present invention, the pressure measuring device includes: the tube capable of being fixed to the sample body along the surface thereof; the pressure sensor fixed inside the tube; the pipe for supplying the reference pressure to the pressure sensor; the closing plug fixed inside the tube to have the predetermined gap from the pressure sensor; the space defined between the pressure sensor and the closing plug inside the tube; and the pressure detecting hole penetrating the tube to communicate with the space. Thus, the unsteady pressure on the surface of the sample body can be measured by transmitting to the pressure sensor through the pressure detecting hole and the space. Moreover, since the volume of the space between the pressure sensor and the closing plug both fixed inside the tube is small, the unsteady pressure fluctuations to be measured are prevented from being made unclear. Thus, the measurement accuracy is improved. In addition to this, the volume of the space is set such that the Helmholtz resonance frequency of the space lies outside the frequencies of the fluctuations of the unsteady pressure, thereby preventing the situation where pressure fluctuations caused by Helmholtz resonance are superposed on the unsteady pressure fluctuations to be measured. Thus, the measurement accuracy is further improved.
[0012] According to a second feature of the present invention, in addition to the first feature, the pressure sensor is in contact with the closing plug, and the space is formed of a recess formed in a surface of the closing plug facing the pressure sensor.
[0013] According to the second feature of the present invention, the pressure sensor is in contact with the closing plug, and the space is formed of the recess formed in the surface of the closing plug facing the pressure sensor. Thus, the relative positional relation between the closing plug and the pressure sensor is maintained constantly. Accordingly, the set Helmholtz resonance frequency can be prevented from being deviated.
[0014] According to a third feature of the present invention, in addition to the first or second feature, a signal line for transmitting a pressure signal outputted from the pressure sensor is formed of a shielded wire for blocking noise from outside.
[0015] According to the third feature of the present invention, the signal line for transmitting the pressure signal outputted from the pressure sensor is formed of the shielded wire for blocking the noise from the outside. Thus, the signal line which extends long along the tube hardly picks up the noise. Accordingly, the measurement accuracy can be enhanced.
[0016] According to a fourth feature of the present invention, there is provided a pressure measuring method using the pressure measuring device according to the first or second feature, wherein noise in a pressure signal outputted from a first pressure sensor as said pressure sensor disposed inside air flow is removed with a pressure signal outputted from a second pressure sensor as said pressure sensor disposed outside the air flow.
[0017] According to the fourth feature of the present invention, the pressure signal outputted from the first pressure sensor disposed inside the air flow is calibrated with the pressure signal outputted from the second pressure sensor disposed outside the air flow. Thus, spike noise in the pressure signal of the first pressure sensor are cancelled out by spike noise in the pressure signal of the second pressure sensor. Accordingly, the unsteady pressure fluctuations to be measured can be measured accurately.
[0018] According to a fifth feature of the present invention, there is provided a leakage inspecting device for inspecting leakage of the tube of the pressure measuring device according to the first or second feature, comprising: an annular adhesive part capable of detachably adhering to a periphery of the pressure detecting hole in the tube; a pressure piping connected at one end to the adhesive part; and a pressurizing device connected to the other end of the pressure piping.
[0019] According to the fifth feature of the present invention, the leakage inspecting device includes: the annular adhesive part capable of detachably adhering to the periphery of the pressure detecting hole in the tube; the pressure piping connected at the one end to the adhesive part; and the pressurizing device connected to the other end of the pressure piping. Thus, presence or absence of the leakage can be determined by pressurizing a path from the pressurizing device to the pressure sensor via the pressure piping, the pressure detecting hole, and the space so as to monitor how the pressure changes. At this time, the adhesive part adheres to the periphery of the pressure detecting hole in the tube. Thus, while leakage inspection is performed, an operator does not need to hold the pressure piping with his or her hand. Accordingly, workability is improved significantly.
[0020] Note that a strip tube 11 of an embodiment corresponds to the tube of the present invention, a vehicle body 18 of the embodiment corresponds to the sample body of the present invention, and a standard pressure generator 22 of the embodiment corresponds to the pressurizing device of the present invention. The above and other objects, characteristics and advantages of the present invention will be clear from detailed descriptions of the preferred embodiment which will be provided below while referring to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is an exploded perspective view of a pressure measuring device.
[0022] FIG. 2A is a sectional view taken along line 2 A- 2 A in FIG. 1 and FIGS. 2B to 2D are sectional views taken along line 2 B- 2 B, line 2 C- 2 C and line 2 D- 2 D, respectively, in FIG. 2A .
[0023] FIG. 3 is a schematic view showing a sample body placed in a wind tunnel.
[0024] FIG. 4 is an explanatory diagram of a Helmholtz resonance frequency.
[0025] FIG. 5 is a power spectrum of pressure fluctuations on a surface of the sample body (with no noise countermeasure).
[0026] FIG. 6 is a power spectrum of pressure fluctuations on the surface of the sample body (with noise countermeasure by hardware).
[0027] FIG. 7 is a power spectrum of pressure fluctuations on the surface of the sample body (further with noise countermeasure by software).
[0028] FIGS. 8A and 8B are graphs for comparing output of a normal pressure sensor and output of a dummy pressure sensor.
[0029] FIGS. 9A and 9B are graphs for comparing a result of a FFT process on the output of the normal pressure sensor and a result of the FFT process on the output of the dummy pressure sensor.
[0030] FIG. 10 is a perspective view of a connecting member.
[0031] FIG. 11 is a sectional view taken along line 11 - 11 in FIG. 10 .
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 11 .
[0033] A pressure measuring device of this embodiment is used to measure unsteady pressure on a surface of a vehicle body of an automobile, for example, unsteady pressure on a surface of a front window glass which disturbed air flow behind a side mirror of the automobile hits, or unsteady pressure on a portion of a rear surface of a rear bumper of the automobile from which air flow separates.
[0034] As shown in FIGS. 1 and 2A to 2 D, the pressure measuring device includes a strip tube 11 made of a synthetic resin to be attached to the surface of the vehicle body. The strip tube 11 is a strip-shaped member having flexibility, and its thickness is suppressed to 3 mm or below, for example, so as to reduce an influence which the strip tube 11 causes to air flow. Inside the strip tube 11 , multiple (five in the embodiment) hollow parts 11 a each having a square section and extending in parallel with each other are formed along a longitudinal direction of the strip tube 11 . The strip tube 11 having such a shape can be manufactured by using a method such as cutting, extrusion molding, stereolithography and the like.
[0035] Each hollow part 11 a of the strip tube 11 houses a pressure sensor 12 formed of a semiconductor sensor. The pressure sensor 12 includes a cylindrical sensor body 13 and a signal line 14 led out from one end surface of the sensor body 13 . An inner diameter of the sensor body 13 is substantially equal to a length of one side of the hollow part 11 a . When the sensor body 13 is fixed at a predetermined position in the hollow part 11 a of the strip tube 11 with adhesive 19 (see FIGS. 2C and 2D ), the adhesive 19 seals gaps between an outer surface of the sensor body 13 and an inner surface of the hollow part 11 a.
[0036] A pipe 26 for supplying reference pressure serving as a reference is connected to the sensor body 13 through the hollow part 11 a of the strip tube 11 , and the sensor body 13 detects pressure relative to the reference pressure. Moreover, the signal line 14 is formed of a shielded wire covered with a cover that blocks electromagnetic waves so that the signal line 14 housed in the hollow part 11 a of the strip tube 11 can be prevented from picking up noise.
[0037] A cubic closing plug 15 is inserted in the hollow part 11 a of the strip tube 11 and is fixed with adhesive in such a way as to be in contact with a pressure detecting surface 13 a which forms the other end surface of the sensor body 13 . The closing plug 15 is made of metal, and an end surface thereof facing the pressure detecting surface 13 a of the sensor body 13 is cut out into a U-shaped recess 15 a . A space 16 of a predetermined volume is formed between this recess 15 a and the pressure detecting surface 13 a of the sensor body 13 . A cylindrical pressure detecting hole 11 b penetrating the strip tube 11 communicates with the space 16 .
[0038] The pressure sensor 12 and the closing plug 15 are disposed in each of the five hollow parts 11 a of the strip tube 11 . Here, positions to dispose the pressure sensor 12 and the closing plug 15 may be shifted in the longitudinal direction of the strip tube 11 or aligned in a direction perpendicular to the longitudinal direction of the strip tube 11 . Moreover, the pressure sensor 12 and the closing plug 15 are not necessarily disposed in all hollow parts 11 a of the strip tube 11 ; the pressure sensor 12 and the closing plug 15 may be disposed only in one or a plurality of predetermined hollow parts 11 a as needed.
[0039] As shown in FIG. 3 , two strip tubes 11 , 11 ′ are attached to portions of a surface of a vehicle body 18 of an automobile which is a sample body placed inside a wind tunnel 17 . One is a normal strip tube 11 attached to a portion where pressure measurement is to be performed, while the other is a dummy strip tube 11 ′ attached to a portion exposed to no wind. A normal pressure sensor 12 and a dummy pressure sensor 12 ′ are provided inside the normal strip tube 11 and the dummy strip tube 11 ′, respectively. The normal strip tube 11 and the dummy strip tube 11 ′ are completely the same, and the normal pressure sensor 12 and the dummy pressure sensor 12 ′ are completely the same as well.
[0040] Signal lines 14 , 14 ′ extending from the two pressure sensors 12 , 12 ′, respectively, are led out from end portions of the strip tubes 11 , 11 ′, respectively, through the respective hollow parts 11 a so as to be connected to an external pressure measuring unit 20 . The pressure measuring unit 20 amplifies and A/D converts pressure signals outputted by the two pressure sensors 12 , 12 ′, and then performs a process to remove spike noise, thereby calculating pressures at the pressure detecting holes 11 b.
[0041] Meanwhile, the pressure measuring device of this embodiment is configured to measure subtle pressure fluctuations in a frequency domain of 1 Hz to 10 KHz, for example, of unsteady air flow flowing on the surface of the vehicle body 18 . Here, assume that the pressure sensor 12 is provided outside the strip tube 11 and that the pressure detecting hole 11 b in the strip tube 11 and the pressure sensor 12 are connected to each other through the elongated hollow part 11 a of the strip tube 11 . In this case, unsteady and subtle pressure fluctuations on the surface of the vehicle body 18 are made unclear through the elongated hollow part 11 a , thus causing a problem of being unable to obtain sufficient measurement accuracy. However, in this embodiment, the pressure sensor 12 is provided in proximity to the pressure detecting hole 11 b , thereby eliminating a problem of deterioration of the measurement accuracy due to pressure fluctuations made unclear through the elongated hollow part 11 a.
[0042] As described above, in this embodiment, the pressure fluctuations on the surface of the vehicle body 18 can be measured without being made unclear by reducing a size of the space 16 which the pressure detecting surface 13 a of the sensor body 13 of the pressure sensor 12 faces. On the other hand, if air in the space 16 resonates due to unsteady air flow flowing outside the pressure detecting hole 11 b (Helmholtz resonance), and a frequency of that resonance is close to the frequencies of the pressure fluctuations to be measured (e.g. 1 Hz to 10 KHz), the measurement accuracy of the pressure sensor 12 might possibly be deteriorated. Hereinbelow, a countermeasure against the Helmholtz resonance will be described.
[0043] As shown in FIG. 4 , the space 16 and the pressure detecting hole 11 b in the strip tube 11 can be modeled as a structure including a box as the space 16 and a nozzle as the pressure detecting hole 11 b attached to the box. When supposing a virtual vibration system having air inside the nozzle as a mass and air inside the box as a spring, its resonance frequency is called a Helmholtz resonance frequency. When a volume of the space 16 is V, a diameter of the pressure detecting hole 11 b is D, a height of the pressure detecting hole 11 b is H, a sectional area of the pressure detecting hole 11 b is S, and a speed of sound is c, a Helmholtz resonance frequency f of the space 16 is expressed as below.
[0000]
f
=
c
2
π
S
V
(
H
+
0.8
D
)
[
Formula
1
]
[0044] Thus, a shape of the recess 15 a of the closing plug 15 is changed so as to change the volume V of the space 16 formed therein such that the Helmholtz resonance frequency f of the space 16 is shifted to a domain higher than 10 KHz. Accordingly, deterioration of the pressure measurement accuracy can be prevented. Here, since adjustment of the Helmholtz resonance frequency f of the space 16 can be done simply by changing the shape of the recess 15 a of the closing plug 15 , the adjustment is extremely easy. In addition, since the closing plug 15 is fixed at such a position as to contact the pressure detecting surface 13 a of the sensor body 13 , the volume V of the space 16 can always be maintained at a constant volume.
[0045] FIG. 5 is a power spectrum of pressure fluctuations on the surface of the vehicle body 18 before a countermeasure by hardware such as a shield and the like is taken for the signal line 14 . A broken line corresponds to theoretical values, and a solid line corresponds to measured values. The measured values indicated by the solid line contain large noise, and a predetermined pressure resolution is not achieved (see the broken line). Note that a vertical axis in each of FIGS. 5 to 7 is a logarithmic scale, and each point in the scale is equivalent to pressure 10 times.
[0046] FIG. 6 is a power spectrum of pressure fluctuations on the surface of the vehicle body 18 after the above-mentioned countermeasure by hardware is taken. Since the noise is reduced, the resolution is improved (see the broken line). However, the predetermined pressure resolution is still not achieved. Thus, a spike noise countermeasure by software is necessary.
[0047] Specifically, as clearly seen from a comparison of an output signal of the normal pressure sensor 12 shown in FIG. 8A and an output signal of the dummy pressure sensor 12 ′ shown in FIG. 8B , the output signals of the two pressure sensors 12 , 12 ′ contain spike noise at the same time, but it is impossible to remove the noise component even if the output signals are directly subtracted from each other.
[0048] For this reason, as shown in FIGS. 9A and 9B , FFT (fast Fourier transform) is performed to the output signals of the two pressure sensors 12 , 12 ′, and the results are subtracted from each other in the frequency domain. FIG. 7 shows that the noise component is greatly reduced and the predetermined pressure resolution is obtained (see the broken line).
[0049] Next, a method of checking leakage of the strip tube 11 and a method of checking wiring of the signal lines 14 will be described.
[0050] In the hollow part 11 a of the strip tube 11 , the space 16 sandwiched between the pressure sensor 12 and the closing plug 15 is defined, and the space 16 communicates with ambient air through the pressure detecting hole 11 b . The pressure measurement accuracy of the pressure sensor 12 is deteriorated if, for example, there is a gap between the hollow part 11 a of the strip tube 11 and the pressure sensor 12 or between the hollow part 11 a of the strip tube 11 and the closing plug 15 , or there is a crack in the strip tube 11 in a portion facing the space 16 . Thus, it is necessary to check airtightness of the space 16 .
[0051] In addition, to measure distribution of pressure at each part on the vehicle body 18 , the signal lines 14 of several tens or several hundreds of pressure sensors 12 need to be properly connected to the pressure measuring unit 20 . Thus, it is necessary to check whether or not the signal lines 14 are properly wired.
[0052] FIGS. 10 and 11 show a connecting member 21 for performing the leakage check and the wiring check. The connecting member 21 includes: a flexible pressure piping 23 connected to a standard pressure generator 22 which supplies predetermined pressure; a metal pipe 24 connected to a tip end of the pressure piping 23 ; and an adhesive part 25 provided in such a way as to surround an outer periphery of the metal pipe 24 and made of a flexible, self-adhesive material such as butylene rubber. The adhesive part 25 is capable of adhering to the strip tube 11 and the body 18 to which the strip tube 11 is attached, and is also capable of being detached many times so as to be repeatedly usable. In an adhering surface of a tip end of the adhesive part 25 formed in an annular shape, a circular recess 25 a is formed, to which a tip end of the metal pipe 24 is opened.
[0053] Accordingly, in a state where the adhesive part 25 is adhered such that its recess 25 a covers the pressure detecting hole 11 b of the strip tube 11 attached to the vehicle body 18 , standard pressure is supplied from the standard pressure generator 22 to the pressure detecting hole 11 b of the strip tube 11 through the pressure piping 23 and the metal pipe 24 so as to monitor output of the pressure sensor 12 , thereby being able to reliably determine occurrence of leakage. Moreover, once the adhesive part 25 is adhered, the adhesive part 25 is not be detached even with an operator's hand off, unless it is forcibly pulled. Thus, the operator does not need to hold the connecting member 21 with his or her hand during the check. Accordingly, workability is improved significantly.
[0054] Note that when the connecting member 21 is manufactured, the adhesive part 25 formed in a tape shape may be wound around the outer periphery of the metal pipe 24 so as to be able to be shaped into a predetermined shape without requiring any special mold. Accordingly, manufacturing cost is reduced.
[0055] Moreover, although the connecting member 21 is used in the embodiment for checking leakage of the strip tube 11 housing the pressure sensor 12 therein and for checking wiring of the signal line 14 , the connecting member 21 can be used for checking strip tubes 11 other than the one mentioned above. For example, the connecting member 21 can be used to perform the leakage check and the wiring check even in a case where: the strip tube 11 has the pressure detecting hole 11 b at one end or an intermediate portion of the hollow part 11 a ; the other end of the strip tube 11 is connected to a pressure sensor disposed outside; and static pressure in the pressure detecting hole 11 b is transmitted to the pressure sensor through the hollow part 11 a . In this case, if the strip tube 11 is bent in a middle, thereby closing the hollow part 11 a , pressure from the standard pressure generator 22 is not be transmitted to the pressure sensor. Accordingly, it is possible to also determine whether or not the strip tube 11 is bent.
[0056] Although an embodiment of the present invention has been described above, various design changes can be made to the present invention without departing from the gist thereof.
[0057] For example, the sample body of the present invention is not limited to the vehicle body 18 of the automobile in the embodiment but may be a body of an aircraft, a body of a building, models thereof, or the like.
[0058] Moreover, although the pressure sensor 12 and the closing plug 15 are disposed in contact with each other in the embodiment, they may be disposed with a predetermined gap therebetween.
|
A pressure measuring device includes: a tube fixable to a sample body along its surface; a pressure sensor and a closing plug both fixed inside the tube with a predetermined gap therebetween; a pipe for supplying reference pressure; a space defined between the sensor and the plug; and a pressure detecting hole penetrating the tube and communicating with the space. Since a volume of the space between the sensor and the plug is small, unsteady pressure fluctuations to be measured are prevented from being made unclear, thereby improving measurement accuracy. Additionally, the volume is set such that a Helmholtz resonance frequency of the space lies outside fluctuation frequencies of the unsteady pressure, thereby preventing superposition of pressure fluctuations by Helmholtz resonance on the unsteady pressure fluctuations to be measured, thus, further improving the measurement accuracy.
| 6
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for producing casks capable of ultimate storage with radioactive wastes by filling the wastes to which cement has been added, into containers, taking radiation shielding into consideration. The invention further relates to casks for use in the method.
2. Description of the Prior Art
Radiation shielding has been taken into account heretofore in wastes of different activity level by making the walls of concrete containers for receiving the wastes of different thicknesses as described in the paper "Some Techniques for the Solidification of Radioactive Wastes in Concrete" in the journal "Nuclear Technology", Vol. 32, Jan. 1977, pages 30 to 38 in particular page 36.
SUMMARY OF THE INVENTION
An object of the invention is to increase the activity content in a cask in order to accommodate more wastes or wastes with higher activity in the same volume. Wastes of interest here are particularly activity carriers accumulated in aqueous form, such as evaporator concentrate, filter sludge, ion exchanger suspensions, etc.
With the foregoing and other objects in view, there is provided in accordance with the invention a method for producing casks capable of ultimate storage of radioactive wastes by filling the wastes to which cement has been added into containers taking radiation shielding into consideration, the improvement comprising filling the casks with radioactive wastes in at least two stages with partial quantities of the radioactive wastes located concentrically to each other, the volume-specific activity of which partial quantities increases from stage to stage from the outside in by at least a factor of 2.
In accordance with the invention, there is provided a cask for ultimate storage of radioactive wastes comprising a plurality of thin-walled hollow bodies nested into each other and supported against each other by spacers which also increase the strength of the cask, filling tubes extending into the spaces between the hollow bodies and into the innermost hollow body, and a common venting tube inserted in an opening which connects with all the spaces.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for producing casks capable of ultimate storage with radioactive waste, and cask produced in accordance with this method, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention, however, together with additional objects and advantages thereof will be best understood from the following description when read in connection with the accompanying drawings, in which:
FIG. 1 schematically shows an installation for carrying out the method according to the invention.
FIG. 2 shows a simplified perspective view of a cask according to the invention.
FIGS. 3 and 4 are two orthogonal views of the casks with further details.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to the invention, the casks are filled in at least two stages with partial quantities which are disposed concentrically with each other and the specific volume activity of which increases from step to step, from the outside inward, by at least a factor of 2.
With the invention a higher activity content is made possible by a cask design which is somewhat more complex than the known design, because partial quantities with lower activity per volume form shielding for partial quantities with higher activity which are arranged further in the interior of the cask.
Radioactive wastes of a given specific radioactivity can be depleted for making the outer partial quantities, for instance, by precipitation. Radioactive wastes can also be enriched for the innermost partial quantity. Methods suitable for enrichment are known. Successive steps of a decontamination process give products of different radioactivity. Of particular advantage, a different overall radioactivity would be obtained by charging to the cask partial quantities with different radioactivities.
The partial quantities are preferably formed into the shape of a cube because it approximates the ideal shape of a sphere most closely, although other cask shapes may be employed. In the case of a cube, the cask consists of an inner cube with the smallest side length and highest specific activity, which is surrounded by several, but at least one body which is cube-shaped externally. The wall thickness created by the inclusion of the body must correspond at least to the required shielding thickness and be, for instance, equal to one-half the side length of the innermost cube. However, spherical partial quantities may be arranged concentrically. Furthermore, cylindrical shapes can also be used economically where the end faces of the cylinders are provided with plane walls of a thickness equal to the wall thickness of the cylinders nested within each other.
The outside of the partial quantities can advantageously be bounded, independently of their shape, by thin-walled hollow bodies which are nested within each other and are supported against each other by spacers designed as armor. Such hollow bodies can consist of plastic or of sheet metal. The inner hollow bodies can be connected via tubes to the outside of the outermost hollow body, thus creating filling canals. If venting is required, this can be achieved advantageously by a tube which leads into the innermost hollow body and has connecting openings into the region of the other hollow bodies.
To explain the invention in greater detail, an embodiment example will be described, referring to the drawings.
The installation shown in FIG. 1 comprises a first container 1, in which evaporator concentrate is collected. The evaporator concentrate can be pretreated there, for instance, by chemical treatment such as precipitation and/or by forming flakes. It is then transported via line 2 to a decanter 3.
A further container 5 contains filter concentrate. This involves filter sludge. The filter concentrates can likewise be put in the decanter 3 via line 6. The filter concentrates from container 5 may be fed through line 7, shown dashed, into a liquid line 8 which leads from the decanter 3 to a thickener 10.
The thickener 10 is substantially an evaporator vessel in which by feeding or replenishing decontaminated raw solution, a liquid volume as small as possible is produced for later cementing. The thickener 10 is connected via a line 11 to a cementing facility 12.
The discharge of solids from the decanter which contains the substances enriched with higher radioactivity is transported via a gravity line 14 into a sludge container 15. The moisture content of the sludge can be, for instance, about 50 percent. The solid matter is conducted from the sludge container 15 through line 16 into line 11 leading to the cementing facility 12.
The cementing facility 12 operates preferably with continuous flow. With a worm mixer it causes intimate mixing of the liquid-containing radioactive wastes with cement which is fed from a silo and to which additives, setting accelerators or inhibitors can be added as required. However, the latter can also be added to the concentrate in liquid form. The discharge 18 of the cementing facility 12 which may be equipped with a pump for thickened material leads into the casks 20 in accordance with the invention.
The casks 20 can consist, for instance, as is shown in FIG. 2, of four concentrically arranged cubes 21, 22, 23 and 24. The side length of the cubes depends on their activity inventory. In this embodiment example, the side length of the outermost cube 24 is 2 m, that of the innermost cube 21 is 50 cm. The cubes 22 and 23 have side lengths of 1 m and 1.50 m. The cubes 22, 23 and 24 have the same wall thicknesses of 25 cm each in this example.
As is shown in FIGS. 3 and 4, the cubes are constructed by means of thin-walled metal sheets 25 which form the outer boundaries of the cubes 21 to 24. The spaces 27, 28 and 29 are equipped with armor 30 which is only indicated and is required for a self-supporting design. The armor can, at the same time, form the spacers between the metal sheets 25.
Two tubes 32, starting from the surface 33 of the sheet metal envelope 24, each leads through the metal sheets 25 located on the top side into the space 29. Two further tubes 34 lead from the surface 33 into the space 28, and again two further tubes 35 lead into the space 27. These tubes serve as immersion tubes for the rising filling of the individual tubes without air inclusions. A common tube 37 for venting is provided for all partial quantities which extends from the top side of the cube 21 vertically upward and is connected to the hollow spaces 27, 28 and 29 to vent openings 40, 41 and 42. A pipe stub 43 is placed on the tube 37 and serves as a rising gate for the innermost chamber with the wall 21. Similar rising gates can also be placed on the tubes 32, 34 and 35.
FIG. 4 shows that the filling tubes 32, 34, 35 and 37 are distributed uniformly over the top side 33 of the cask 20. It is also seen therefrom that the corners 45 of the cask are reinforced with so-called "iso-corners" to enable commercially available handling tools to be used for lifting the cask 20.
The cask 20 is filled with waste of different activity and stirred with cement. For the outer layer of the cask 20, i.e. for the space 29, the weakly active salt-loaded clear overflow material from the thickener 10 which is further thickened for reducing the volume is used. In this example, it forms a specific volume of 4.6 m 3 with a specific activity of about 2 mCi/m 3 .
The space 28 is filled primarily with filter concentrate from the container 5. Its specific activity is, for example, about 0.1 Ci/m 3 . The specific volume of 2.4 m 3 thereby contains 0.25 Ci.
The precipitation sludge of the decanter 3 from the sludge container 15 is fed into the third chamber 27. Additionally, the reactor water purification resins can be added, if desired, via the line 7. Here, the permissible specific activity is, for instance, about 10 Ci/m 3 . The volume of the chamber 27 is 0.875 m 3 , so that an activity inventory of about 10 Ci can be accommodated.
While the innermost cube 21 has only a specific volume of 0.125 m 3 , it can be filled with specific activity of about 500 Ci/m 3 , so that about 50 Ci are taken up in this small space. The total activity of the cask 20 is therefore about 70 Ci without exceeding on the outside the permissible dose rate of, for instance, 200 mrem/h and 10 mrem/h at a distance of two meters from the cask 20. As compared to the dose rate the activity contents furthermore are nuclide-dependent. The total weight of the cask 20 is about 20 tons which is at the same time a co-determining factor for the dimensional limits.
The foregoing is a description corresponding, in substance, to German application No. P 35 13 692.8, dated Apr. 16, 1985, international priority of which is being claimed for the instant application and which is hereby made part of this application. Any material discrepancies between the foregoing specification and the specification of the aforementioned corresponding German application are to be resolved in favor of the latter.
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Method for producing casks capable of ultimate storage of radioactive wastes by filling the wastes to which cement has been added into containers taking radiation shielding into consideration. The casks are filled in at least two stages with partial quantities located concentrically to each other, the volume-specific activity of which increases from stage to stage from the outside in by at least a factor of 2.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display, and in particular to a liquid crystal display with a supporting base.
2. Description of the Related Art
In FIG. 1 , a conventional liquid crystal display on a surface 5 is situated in a stable condition. W is the weight of the display unit 1 , and F is external force used for lifting up the display unit 1 . The force F is directly on the display unit 1 and rotated the first pivot 22 in a counterclockwise direction.
The liquid crystal display has a display unit 1 and a supporting base 2 . The supporting base 2 has a first section 21 , a first pivot 22 , a second section 23 , a second pivot 24 , a third section 25 and a plate 26 . The first pivot 22 and the second pivot 24 have the same structure, and the first pivot 22 connects the first section 21 and the second section 23 , and the second pivot 24 connects the second section 23 and the third section 25 . The display unit 1 is connected to the third section 25 by the plate 26 . The plate can be integrally formed on the end of third section 25 , and the display unit 1 can be directly mounted on the third section 25 . Thus, the position of the display unit 1 can be adjusted upwardly or downwardly by rotating the second section 23 around the first pivot 22 , and the tilt angle of the display unit 1 can be adjusted by rotating the third section 25 around the second pivot 24 .
FIG. 2 is a cross-section of the first pivot 22 of FIG. 1 along its longitudinal direction. The fixed element 211 is a part installed on the first section 21 of the supporting base 2 , and the first section is positioned on the surface 5 motionlessly. The movable element 231 is a part installed on the second section 23 of the supporting base 2 . A bolt 221 passes through the fixed element 211 and the movable element 231 and is secured by a nut 222 . Several washers 224 function as frictional disks between the bolt 221 and the fixed element 211 , as well as between the fixed element 211 and the movable element 231 . The washers 224 are made of soft material, such as rubber, plastic or the like. A U-shaped washer 223 and another washer 224 are disposed between the movable element 231 and the nut 222 . The U-shaped washer 223 is used to keep the washer 224 attaching to the fixed element 211 or the moveable element 231 . The U-shaped washer 223 can be made of rigid, flexible material, such as steel, copper or the like.
When the nut 222 rotates toward the head 221 H, the U-shaped washer 223 is pushed and moved toward the washer 224 disposed next to the movable element 231 , and the fixed element 211 and the movable element 231 are pressed and pushed to approach each other, bracketed by the deformed washers 224 . These deformed washers 224 provide a frictional force to the fixed element 211 and the movable element 231 , to balance the weight of the display unit 1 .
Referring again to FIG. 1 and also to FIG. 3 , as the liquid crystal display is placed on the surface 5 , the weight W of the display unit 1 exerts a gravity torque T W by the weight of the display unit 1 on the first pivot 22 in a clockwise direction. In the same time, a static frictional force is generated within the first pivot 22 and exerts a frictional torque T F1 on the first pivot 22 in a counterclockwise direction.
In the first pivot 22 , frictional torque T F1 is equal to gravity torque T W (T F1 =T W ), i.e., the display unit 1 is stable. The static frictional force, however, is variable. The amount of the static frictional force is increased when the external force applied on an object increases. When the static frictional force is increased to a critical value, i.e., maximum static frictional force, the object is moving because of the external force, The frictional force becomes a dynamic friction force, and the value of the frictional force decreases and reaches a constant. In this related art, T F1 is a frictional torque generated by the maximum static frictional force within the first pivot 22 .
When the display unit is stable on the surface 5 , the direction of the frictional torque T F1 is opposite to that of the gravity torque T W . When an external force is applied to lift the display unit 1 , the direction of the frictional torque T F1 is changed. When the display unit 1 is successfully lifted, the torque generated by external force F must overcome the sum of the frictional torque T F1 and gravity torque T W . In FIG. 4 , T F2 is a torque generated by the external force F in a counterclockwise direction on the first pivot 22 . Thus, torque T F2 must be larger than the sum of frictional torque T F1 and gravity torque T W (T F1 +T W ). The direction of frictional torque T F1 (clockwise, in FIG. 4 ) is opposite to the direction of frictional torque T F1 (counterclockwise, in FIG. 3 .) because the direction of the maximum static frictional force is changed.
In general, the nut 222 secured on the bolt 221 is tightly driven, such that the washers 224 can be closely attached on the fixed element 211 and the movable element 231 , and therefore sufficient frictional force is generated therebetween to balance the weight of the display unit 1 . However, the display unit 1 becomes difficult to adjust or position at a predetermined height or angle from the nut 222 on the bolt 221 being over-tightened.
When the nut 222 is tightly connected to the bolt 221 , the maximum static frictional force within the first pivot 22 is large and the frictional torque T F1 is also very large. Therefore, the torque T F2 , generated by the external force F, used to overcome the frictional torque, is also large.
If the external force F is too big, the first section will also be lifted to leave the surface 5 when adjusting the position of the display unit 1 as shown in FIG. 5 . Therefore, another force N is need to apply on the first section 21 of the supporting base 2 to prevent the first section 21 from leaving the surface 5 . However, it is inconvenient to manually adjust the position or the angle of the display unit 1 .
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to provide a pre-force mechanism in a pivot of a liquid crystal display, allowing easy lifting of a display unit.
The invention provides a liquid crystal display having an supporting base, a display unit, and a pre-force mechanism. The supporting base has at least two sections and at least one pivot, the two sections connected by the pivot.
The display unit is lifted by the supporting base. The display unit is connected to one of the two sections, and exerts a first torque on the pivot by a weight of the display unit. The pre-force mechanism is connected to the pivot and exerts a second torque on the pivot. The second torque and the first torque are in opposite directions. Therefore, the torque generated by external force is substantially reduced, and the display unit can be easily lifted or adjusted.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
FIG. 1 is a schematic view of a conventional liquid crystal display;
FIG. 2 is a cross-section of a first pivot ( 22 ) of the liquid crystal display of FIG. 1 along its longitudinal direction;
FIG. 3 is a diagram of the equilibrium of force (torques) on the liquid crystal display in FIG. 1 ;
FIG. 4 is a diagram of the equilibrium of force (torques) on the liquid crystal display in FIG. 1 , wherein a display unit ( 1 ) of the liquid crystal display is lifted;
FIG. 5 is a schematic view of the liquid crystal display in FIG. 1 , wherein the display unit ( 1 ) of the liquid crystal display is lifted;
FIG. 6 is a diagram of the equilibrium of force (torques) on a liquid crystal display according to the present invention;
FIG. 7 is a diagram of the equilibrium of force (torques) on the liquid crystal display of the present invention, wherein the display unit ( 1 ) of the liquid crystal display is lifted;
FIG. 8 is a schematic view of the liquid crystal display according to the present invention;
FIG. 9 is a schematic view showing the relationship between a pre-force mechanism ( 3 ) and a first pivot ( 22 ′) of the liquid crystal display in FIG. 8 ;
FIG. 10 is a cross-section of the first pivot ( 22 ′) of the liquid crystal display of FIG. 8 along its longitudinal direction;
FIG. 11 is a schematic view of the liquid crystal display of FIG. 8 , wherein a pre-force (P) generated by the pre-force mechanism ( 3 ) is applied in the liquid crystal display;
FIG. 12 is a partial view of the liquid crystal display of FIG. 8 , wherein a wear liner ( 35 ) is disposed between a second section ( 23 ) of a supporting base ( 2 ) and a rod ( 33 ) of the pre-force mechanism ( 3 );
FIG. 13A–13B are two schematic views of the liquid crystal of FIG. 8 , wherein the second section ( 23 ) of the supporting base ( 2 ) in FIG. 13A is in an initial state, and the second section ( 23 ) of the supporting base ( 2 ) in FIG. 13B is in a raised condition when the display unit ( 1 ) is lifted and the second section ( 23 ) of the supporting base ( 2 ) rotates about an axis (A) of the first pivot ( 22 ′);
FIG. 13C is a simulation diagram of deployment of the second section ( 23 ) of the supporting base ( 2 ), wherein a distance from point (A) to point (C) represents the state of the second section ( 23 ) of the supporting base ( 2 ) in FIG. 13A , and a distance from point (A) to point (C′) represents the state of the second section ( 23 ) of the supporting base ( 2 ) in FIG. 13B ; and
FIG. 14 is a schematic view of an exemplary rod ( 33 ′) of the pre-force mechanism ( 3 ).
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 6 , when the liquid crystal display is situated in a stable condition, the present invention provides a pre-force mechanism 3 (as FIG. 8 ) to generate a second torque T P in a pivot of a liquid crystal display (LCD) in advance, such that the second torque T P is formed to overcome a first torque T W generated by the weight of the display unit 1 . The direction of the first torque T W is opposite to that of the second torque T P . In addition, a third torque is exerted on the pivot of the LCD because of the frictional force within the pivot. When the LCD is situated in the stable condition, the first torque T W generated by the weight of the display unit 1 is larger than the second torque T P formed by the pre-force mechanism 3 and the third torque T F3 formed by the frictional force, that is, T W ≧T F3 +T P . Because of the second torque T P , the third torque T F3 , the frictional torque for balancing the weight of the display unit 1 , can be reduced. That is to say, the frictional torque T F3 in FIG. 6 is smaller than the frictional torque T F1 in FIG. 4 .
When an external force F is applied to lift the display unit 1 , the fourth torque T F4 is the torque generated by the external force F on the first pivot 22 in a counterclockwise direction. In addition, the direction of the frictional force within the pivot is changed.
The expression of the equilibrium formula of the state in FIG. 7 is written as T F4 +T P =T F3 +T W . When the display unit 1 is lifted because of the external force F, the torque T F4 generated by external force F needs to overcome the first torque T W generated by the weight of the display unit 1 and the frictional torque T F1 . However, the second torque T P is exerted on the pivot in advance. Therefore, the torque TF 4 can be reduced and the external force F can also be reduced. That is to say, the display unit 1 can be lifted or adjusted without additional force N on the first section 21 as shown in FIG. 5 .
It can be seen that frictional torque T F3 as the LCD is positioned in the stable status as shown in FIG. 6 is effectively reduced and the torque T F4 generated by external force F is reduced commensurately.
In FIG. 8 , a liquid crystal display D of the present invention has a display unit 1 , a supporting base 2 ′ and a pre-force mechanism 3 . The supporting base 2 ′ has a first section 21 , a first pivot 22 ′, a second section 23 , a second pivot 24 , a third section 25 and a plate 26 . The first pivot 22 ′ and the second pivot 24 have the same structure, and the first pivot 22 ′ connects the first section 21 and the second section 23 , and the second pivot 24 connects the second section 23 and the third section 25 . The display unit 1 is connected to the third section 25 by the plate 26 . In another embodiment, the plate can be integrally formed on the end of third section 25 , and the display unit 1 can be directly mounted on the third section 25 . Thus, the position of the display unit 1 can be adjusted upwardly or downwardly by rotating the second section 23 around the first pivot 22 ′, and the tilt angle of the display unit 1 can be adjusted by rotating the third section 25 around the second pivot 24 .
The pre-force mechanism 3 has an annular stopper 31 , a resilient element 32 and a rod 33 . The stopper 31 is disposed in the hollow second section 23 and rotates around the first pivot 22 ′ when the second section 23 rotates around the first pivot 22 ′. The stopper 31 has an orifice 311 penetrated by the rod 33 . In the present embodiment, the resilient element 32 is a spring.
In FIG. 9 , the rod 33 has a first end 331 , a second end 332 and a middle portion 333 located between the first end 331 and the second end 332 . The second end 332 is thinner than the middle portion 333 so that the spring 32 is disposed on the middle portion 333 of the rod 33 and confined and pressed between the stopper 31 and the second end 332 . Both the rod 33 and the spring 32 are disposed in the second section 23 . The first end 331 of the rod 33 is hooked at an opening 212 of the first pivot 22 ′ (See FIG. 10 ), such that the rod 33 is coupled to the fixed element 211 ′ and the rod 33 rotates around the first pivot 22 ′.
FIG. 10 is a cross-section of the first pivot 22 ′ of FIG. 8 along its longitudinal direction. The fixed element 211 ′ is a part installed on the first section 21 of the supporting base 2 , and the first section 21 is positioned on the surface 5 motionlessly. A through hole 212 is formed on the fixed element 211 ′. The movable element 231 is a part installed on the second section 23 of the supporting base 2 . A bolt 221 passes through the fixed element 211 ′ and the movable element 231 , and is secured by a nut 222 . Several washers 224 function as frictional disks are positioned between the bolt 221 and the fixed element 211 ′, and between the fixed element 211 ′ and the movable element 231 . The washers 224 are made of soft material, such as rubber, plastic or the like. A U-shaped washer 223 and another washer 224 are disposed between the movable element 231 and the nut 222 . The U-shaped washer 223 is used to keep the washer 224 attaching to the fixed element 211 or the moveable element 231 . The U-shaped washer 223 can be made of rigid, flexible material, such as steel, copper or the like.
When the nut 222 rotates toward the head 221 H, the washer 223 is pushed and moved toward the washer 224 next to the movable element 231 . The fixed element 211 ′ and the movable element 231 are then pressed and pushed to approach each other, bracketed by the deformed washers 224 . These deformed washers 224 provide frictional force on the fixed element 211 ′ and the movable element 231 , such that the frictional force is applied to balance the weight of the display unit 1 .
Referring to FIG. 11 and also FIG. 8 , the spring 32 confined between the stopper 31 and the second end 332 is compressed so as to generate a force P, pushing the opening 212 of the first pivot 22 ′ through the rod 33 . That is to say, the spring 32 is a pre-stressed element and generates the force P to rotate the second section 23 around the first pivot 22 ′ in a counterclockwise direction, i.e., the pre-torque T P in FIG. 6 is provided by the force P acting on the fixed element 211 ′. The pre-torque T P is applied to overcome first torque T W generated by the weight W of the display unit 1 and the reduced frictional torque T F3 in FIG. 7 , such that the display unit 1 is easily lifted or adjusted without additional force on the first section 21 .
When the display unit 1 is lifted or adjusted, i.e., the second section 23 rotates about the first pivot 22 ′, in a counterclockwise or clockwise direction, the second end 332 of the rod 33 is moved within the second section 23 , as demonstrated by the formulas in the following description.
To reduce the frictional resistance of moving the second end 332 and eliminate noise generated by the friction, a wear liner 35 can be disposed between the second end 332 of the rod 33 and the second section 23 of the supporting base 3 ′, i.e., the wear liner 35 can be disposed on the outside of the second end 332 of the rod 33 or on the inner wall of the second section 23 of the supporting base 3 ′.
In FIGS. 13A and 13B , A is a center of the first pivot 22 ′, Bp is the location of the opening 212 , and Cp is the center of the stopper 31 . When the second section 23 rotates around the first pivot 22 ′, the center of the stopper 31 is moved from point Cp to point C′.
FIG. 13C is a resultant diagram of FIGS. 13A and 13B together. Distance “ ApBp ” measured from points Ap to Bp is a constant whenever the second section 23 rotates around the first pivot 22 ′, and “ ApBp ” is defined as “r” ( ApBp =r). With respect to point Ap, distance “ ApCp ” measured from points Ap to Cp, and distance “ ApC′ ” measured from points Ap to C′ are also constant and have the same value, and therefore, “ ApCp ” and “ ApC′ ” are defined as “R” ( ApCp = ApC′ =R). In addition, the distance between points Bp and Cp is “d”, and the distance between points Bp and C′ is “d′”.
Based on Cosine equation, a geometric formula for the triangle ΔApBpC is expressed as follows:
d 2 =r 2 +R 2 −2 rR cos θ l (1)
Another geometric formula for the triangle ΔApBpC′ is expressed as follows:
d′ 2 =r 2 +R 2 −2 rR cos θ h (2)
By subtracting (2) from (1) to get a formula (3) as follows:
d 2 −d′ 2 =2 rR (cos θ h −cos θ l ) (3)
In FIG. 13C , θ h is an angle between edge ApBp and ApC′ , and θ l is an angle between edge ApBp and ApCp , θ h is small than θ l , and thus cos θ h exceeds cos θ l ,
θ h <θ l cos θ h >cos θ l cos θ h −cos θ l >0 (4)
Putting (4) into (3) results in formula (5) as follows:
d
2
-
d
′2
=
2
rR
(
cos
θ
h
-
cos
θ
l
)
>
0
⇒
d
2
-
d
′2
=
(
d
+
d
′
)
(
d
-
d
′
)
>
0
⇒
d
-
d
′
>
0
(
5
)
In formula (5), it is understood that the distance between the opening 212 and the stopper 31 decreases when the second section 23 rotates around the first pivot 22 ′ in a counterclockwise direction, as the distance between the stopper 31 and the second end 332 increases. Thus, the second end 332 of the rod 33 is moved within the second section 23 whenever the second section 23 rotates about the first pivot 22 ′.
Referring to FIG. 14 , a different pre-force mechanism is provided. The rod 33 ′ is a variant of the rod 33 in FIG. 9 . The rod 33 ′ differs from the rod 33 in that the resilient element (spring) is integrally formed on the rod 33 ′. A resilient portion 32 ′ is integrally formed on the second end 332 ′ of the rod 33 ′ and encloses the rod 33 ′. When the rod 33 ′ is properly disposed in the second section 23 of the supporting base 2 ′, the spring 32 ′ is confined between the stopper 31 and the second end 332 and compressed, such that the force (as the same force P in FIG. 11 ) is generated by the compressed spring 32 ′ pushing the opening 212 of the first pivot 22 ′ through the rod 33 ′. Thus, the pre-torque T P overcomes gravity torque T W generated by the display unit 1 , such that display unit 1 can be easily lifted or adjusted without additional force on the first section 21 .
While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to enclose various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
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A liquid crystal display having a supporting base, a display unit and a pre-force mechanism. The supporting base has at least one pivot and at least two sections joined thereby, and the display unit is connected to the supporting base, exerts a first torque on the pivot by the weight of the display unit. The pre-force mechanism is connected to the pivot and exerts a second torque on the pivot. The first torque is opposite to the second torque.
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FIELD OF THE INVENTION
The invention relates to building up an airfoil by depositing cladding layers using an energy beam and control optics. In particular, the invention relates to encircling protruding rib material by the cladding layers.
BACKGROUND OF THE INVENTION
Blades used in the turbine section of gas turbine engines are exposed to combustion gases, high mechanical force, and foreign object impact. This, coupled with the high operating temperature, create high levels of stress in the blade. Blade tips, blade airfoil sections, and blade platforms are particularly susceptible to stress related damages, including areas of wear and cracks. Blade tips, (also known as tip caps), include blade tip shelves (an end piece of the airfoil) and blade squealers (elevated material surrounding the blade tip). The cracks may extend from the tip of the airfoil downward toward the platform, sometimes extending past the blade shelf adjacent the blade tip.
It is known to replace worn or cracked blade squealers with non-structural replacement material. This replacement material is considered non-structural primarily because the stresses are relatively low in this location, and as a result, consequences of damage are relatively minimal in terms of performance. Unfortunately, cracking is very often found below (toward the platform) the tip shelf, extending into the airfoil body. For example, the cracks may extend 30 mm below the blade tip. Replacement of this material (below the squealer) is more difficult and must be considered to be of a more structural requirement, wherein certain minimum mechanical properties must be attained in order to sustain the greater stresses encountered in the airfoil body.
For the most difficult to weld superalloys, there is no known process to replace such extensive portions of a turbine blade. Grinding out and re-welding cracks using a hot box to maximize material ductility during the process has met with limited success. Cutting off the entire distressed blade tip and welding is not possible for at least two reasons. First, the material itself does not accommodate butt welding. It would crack due to shrinkage stresses and high restraint. Second, ribs disposed within the airfoil (serving structural function and cooling air management) could not be accessed for butt welding. Consequently, there is room in the art for improved methods of building and/or repairing blade airfoils.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in the following description in view of the drawings that show:
FIG. 1 schematically shows an exemplary embodiment of paths followed by an energy beam when forming an exemplary embodiment of a cladding layer, where the paths are superimposed on the cladding layer and the cladding layer is disposed on an exemplary embodiment of a substrate.
FIG. 2 is a schematic perspective view of the cladding layer of FIG. 1 being formed on the substrate toward a beginning of the formation process.
FIG. 3 is a schematic sectional view along A-A of FIG. 2 after several cladding layers have been formed.
FIG. 4 schematically shows exemplary embodiments of patterns followed by the energy beam when forming the cladding layer adjacent ribs, where the patterns are superimposed on the cladding layer and the cladding layer is disposed on the substrate.
FIGS. 5-6 schematically show exemplary embodiments of patterns followed by the energy beam while forming exemplary embodiments of a blade tip shelf.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have devised a method of building up an airfoil section of a gas turbine component having an airfoil skin structurally supported by internal ribs, such as a turbine blade. This is accomplished by forming layers of cladding on a bonding surface of a substrate using scanning optics to a melt powder placed on the bonding surface. The cladding layers are deposited around existing rib material that protrudes above the bonding surface, and the cladding layer bonds to the bonding surface and the protruding rib material. The scanning optics generate two melt pools that simultaneously travel along different paths on opposite sides of the protruding rib material to form each cladding layer. Each cladding layer forms a layer of the airfoil, includes side sections, and may include at least one rib section to create a rib where there is no protruding rib material already present. Being able to form an airfoil skin around existing rib sections enables building up of new airfoil sections and repair of existing airfoil sections in a manner not previously possible. With respect to worn airfoils, the inventors have recognized that the ribs are rarely distressed and so it may be most efficient to leave them in place for a repair using the disclosed methods.
In an exemplary embodiment where the substrate is a superalloy, the powder material may include a superalloy metal powder and a flux as described in U.S. patent publication number 2013/0140278 to Bruck et al. and incorporated in its entirety by reference herein. The ability to clad superalloys in this manner, together with the advanced scanning optics now available (e.g. Cambridge Technology Lightning II 4 kW, Scanlab powerSCAN 4 kW, Trumpf PFO 3D 8 kw and IPG 8 kW), and the deposition pattern disclosed herein enables buildup and repair of superalloy components that was not previously possible.
FIG. 1 schematically shows an exemplary embodiment of paths followed by an energy beam when forming an exemplary embodiment of a cladding layer 10 , where the paths are superimposed on the cladding layer 10 and the cladding layer 10 is disposed on an exemplary embodiment of a substrate 12 . The cladding layer 10 may be in the shape of an airfoil and have a skin 14 having a pressure side wall 16 , a suction side wall 18 , a leading edge 20 , a trailing edge 22 , and optionally an additional rib section 24 . The additional rib section 24 represents a rib that is to be formed in addition to the already-existing ribs. The substrate 12 includes a bonding surface (not visible) under the cladding layer 10 . Rib material 26 protrudes (out of the page) above the bonding surface and each instance of the rib material 26 represents some or all of a rib 28 around which the cladding layer 10 is deposited and to which the cladding layer 10 is bonded. In the exemplary embodiment shown, the substrate 12 includes first rib material 30 and second rib material 32 . There may be any number of ribs 28 , and there may also be any number of additional rib sections 24 .
The first rib material 30 is not tapered toward a tip end 40 . Consequently, the first rib material 30 represents essentially a full rib, less any fillets etc associated with bonding an untapered side surface 42 of the first rib material 30 to the pressure side wall 16 . The second rib material 32 is tapered toward a tip end 40 . Consequently, the second rib material 32 represents less than a full rib. With tapered rib material, the cladding layer 10 fills in the portion of the second rib material 32 lost to the taper and bonds to a tapered side surface 44 of the second rib material 32 . Thus, whether the rib 28 includes the untapered side surface 42 or the tapered side surface 44 , it is bonded to an inner perimeter 46 of the cladding layer 10 .
In an exemplary embodiment without an additional rib section 24 , the pressure side wall 16 and the suction side wall 18 may be formed by an energy beam guided by scanning options to form a first path 50 and a second path 52 along which respective melt pools travel. The first path 50 may start at a first path initiation point 54 and traverse a first wall, e.g. the suction side wall 18 , until reaching a first path termination point 56 . The second path 52 may start at a second path initiation point 58 and traverse a second wall, e.g. the pressure side wall 16 , until reaching a second path termination point 60 . The first path initiation point 54 and the second path initiation point 58 may be disposed at a common initiation point 62 . The first path termination point 56 and the second path termination point 60 may be disposed at a common termination point 64 . There may be an optional runon 66 formed at any of the initiation points, such as at the common initiation point 62 . Likewise, there may be an optional runoff 68 formed at any of the termination points, such as the common termination point 64 .
The location of the common initiation point 62 may be selected so that a length of the first path 50 and a length of the second path 52 are the same. In such an exemplary embodiment the scanning optics may be configured to traverse the energy beam along each path at the same rate, thereby taking the same amount of time for the energy beam to traverse the first path 50 as the second path 52 (i.e. the same duration). Alternately, the first path 50 and the second path 52 may be of different lengths. In this case it may take more time to form the longer path if the energy beam traverses each path at the same rate. When the two paths are of differing length but the traversal duration is desired to be the same for each path, the scanning of the energy beam can be still adjusted so that it traverses each path in the same amount of time. For example, if the first path 50 is twenty five percent longer than the second path 52 (e.g. 125 and 100 mm respectively), then the energy beam may spend twenty five percent more time forming the first path 50 as the second path 52 (e.g. 60 and 48 seconds respectively), while traversing each path at the same traversal duration (e.g. ˜2.1 mm/sec for e.g. total process time of 108 seconds). This is made possible because the melt pool of the shorter path will remain liquefied long enough to permit the energy beam to spend more time forming the longer path, even if the power output of the energy beam is the same when forming each path.
When forming the cladding layer 10 a first melt pool (not shown) would follow the first path 50 and a second melt pool (not shown) would follow the second path 52 . If one of the melt pools were to be initiated and the powder material at the common initiation point melted and then solidified before the other melt pool was initiated, then the solidified material at the common initiation point 62 would be remelted by the melt pool that initiated later in time. This remelting (remelt) can be avoided by starting both melt pools at the same time, or close enough in time that only one melt pool (not shown) is formed at the common initiation point 62 . Avoiding remelt reduces the possibility for cracking and creates a stronger cladding layer. Likewise, the melt pool that traverses the first path 50 may be timed to meet with the melt pool that traverses the second path 52 such that they unite into a single melt pool at the common termination point 64 , which avoids remelt at the common termination point 64 . An optional runoff 68 may be positioned at the common termination point 64 and one or more melt pools may be extended off of the part at the runoff 68 . Forming opposite wall sections simultaneously mitigates airfoil warping, and having a continuous, uninterrupted traversal minimizes remelts, which improves the structural integrity of the cladding layer 10 .
When a melt pool approaches the untapered side surface 42 of the first rib material 26 the energy beam and/or scanning optics may change one or more operating parameters to ensure the cladding layer 10 bonds well at a junction 70 between the rib and the cladding layer 10 . For example, a traversal rate of the energy beam may be slowed or power level of the energy beam may be increased to account for additional, localized heat sinking due to the amount of material at the junction 70 . When a melt pool approaches the tapered side surface 44 the energy beam and/or scanning optics may likewise change one or more operating parameters to ensure the cladding layer 10 bonds well at a junction 70 between the rib and the cladding layer 10 . In addition, the path may be widened to ensure the cladding layer 10 reaches the tapered side surface 44 , as is discussed further below.
For portions of the side walls away from the junctions 70 , the power output of the energy beam may be the same for the paths made to form the cladding layer 10 . Alternately, the power output may vary. Still further, the power may be adjusted while the energy beam is traversing a path to accommodate varying heat requirements, such as the width (wall thickness) required for the airfoil.
In an exemplary embodiment with an additional rib section 24 , one of the paths may be varied to form the additional rib section 24 , while the other path may remain unchanged. For example, the first path 50 may remain unchanged, while the second path 52 may be changed to include the additional rib section 24 . In such an exemplary embodiment, the second path would again start from the second path initiation point 58 , which may be the common initiation point 62 , and would end at the second path termination point 60 , which may be the common termination point 64 . However, while traversing the pressure side wall 16 , the energy beam may cause the melt pool to leave the pressure side wall 16 temporarily to form the additional rib section 24 . After forming the additional rib section 24 the energy beam would cause a new melt pool to form on the pressure side wall 16 at a secondary initiation point 72 and traverse the new melt pool to the second path termination point 60 . The melt pool that forms the additional rib section 24 may be timed to arrive at a junction of the additional rib section 24 and the suction side wall 18 at the same time. This would avoid remelt at this location. It is possible that the cladding material on the pressure side wall 16 adjacent the secondary initiation point 72 and already processed by the energy beam may have solidified. Consequently, it is possible that there may be some remelt at the secondary initiation point 72 when the new melt pool is formed
Alternately, upon reaching the additional rib section, the energy beam 100 could be shared essentially simultaneously along three paths. In such an exemplary embodiment three melt pools could exist simultaneously. The melt pool traveling along the pressure side wall 16 could split such that one melt pool would continue along the pressure side wall 16 while another melt pool would continue along the additional rib section and meet a third melt pool at the suction side wall 18 , at which point a single melt pool would continue along the suction side wall 18 . The traversal rate of the melt pool traversing the pressure side wall 16 and the traversal rate of the melt pool traversing the suction side wall 18 could be adjusted independently so the two arrive at the common termination point 64 simultaneously. In this exemplary embodiment remelt could be avoided altogether.
If the cladding process generates a layer of slag on the cladding layer it may be removed as the powder material is solidified, or at the completion of the formation of the cladding layer 10 .
One or more cladding layers 10 may be deposited on a substrate to create or rebuild an airfoil, in which case the above process may be repeated to form as many cladding layers 10 as are necessary.
FIG. 2 is a schematic side view of the cladding layer 10 being formed on the substrate 12 toward a beginning of the formation process. In this exemplary embodiment the substrate 12 is an airfoil 80 having an airfoil pressure side 82 , an airfoil suction side 84 , an airfoil leading edge 86 , an airfoil trailing edge 88 , and a bonding surface 90 , which is, in this exemplary embodiment, an edge 92 of an airfoil skin 94 . An energy beam 100 emanating from an energy beam source 102 and guided by scanning optics 104 is processing powder material 106 placed on the bonding surface 90 . It can be seen that the scanning optics 104 are able to direct the energy beam 100 toward one side of the cladding layer 10 as indicated by a solid energy beam line, and then to the other side of the cladding layer, as indicated by the dotted line. The scanning optics are capable of jumping the beam from one side to the other at a jump rate of approximately 3 m/s. Consequently, two melt pools can be sustained and traversed simultaneously. During the process the powder material 106 melts, solidifies, and bonds to the bonding surface 90 to form the cladding layer 10 .
In an exemplary embodiment where a flux powder is incorporated into the powder material 106 a slag 108 may form on the cladding layer 10 , which is removed before any subsequent cladding layers are deposited. In alternate exemplary embodiments the filler and flux could be preplaced in a distinct preform such as encapsulated in a sleeve that is then positioned at the process location. The filler material in the powder material may have the same chemical composition as the substrate or it may be different.
A dotted line defines a finished profile 110 of an unfinished portion 112 of the airfoil 80 when sufficient cladding layers 10 are deposited to complete the airfoil 80 . (Ribs are not externally visible in a finished airfoil.) The finished profile 110 may represent an airfoil 80 that is being created for the first time, or it may indicate airfoil skin 94 that was previously part of the airfoil 80 but which was removed and which must be replaced to return the airfoil to its original condition. The latter may occur, for example, when an airfoil 80 that has been in service experiences cracking at a tip 114 of the airfoil 80 . The airfoil 80 may be pulled from service and a tip end 116 of the airfoil skin 94 and the unwanted cracks therein are removed, but at least a portion of at least one of the ribs 28 remains, to permit the cladding repair operation disclosed herein. Thus, airfoil skin 94 may be removed to expose underlying rib material. If the airfoil skin 94 is removed from both the airfoil pressure side 82 and the airfoil suction side 84 , the underlying rib material may have spanned (connected to) both sides of the removed airfoil skin 94 .
The protruding rib material may or may not protrude all the way to the tip 114 of the airfoil 80 . For example, there may be some rib material remaining all the way to an end of the rib 28 at the tip 114 of the airfoil 80 . Alternately, some of the rib material at the tip 114 may be removed, but some protruding rib material may be left. In a non limiting example, 30 mm may be removed and cladding layers of 3 mm thickness may be formed until the 30 mm section is rebuilt. When ten layers are deposited the airfoil 80 would be returned to a finished state. An outer surface of the airfoil 80 may require finish machining. An inner surface may be accepted as is.
FIG. 3 is a schematic sectional view along A-A of FIG. 2 after several cladding layers 10 have been deposited. The bonding surface 90 for a first cladding layer 130 is defined by the substrate 12 after the removal of material but before any cladding layers 10 are deposited. Once a cladding layer 10 is bonded to the substrate 12 the deposited cladding layer 10 becomes part of the substrate 12 from the perspective of the next cladding layer 10 . Consequently, the bonding surface 90 for a subsequent bonding layer is a top 132 of an immediately prior cladding layer 10 . This process repeats for each cladding layer 10
The junction 70 of the rib 28 and the airfoil skin 94 is oriented essentially toward a top of the page, while the tapered side surface 44 forms a taper angle 136 with the tapered side surface 44 . As a result, a taper gap 138 forms at an upper surface 140 of each layer between the junction 70 and the tapered side surface 44 . To accommodate this, the cladding layer 10 may be widened to bridge the taper gap 138 so the cladding layer 10 can bond to the tapered side surface 44 . For example, a bonding surface 90 for a second cladding layer 134 would be the top 132 of the first cladding layer 130 , which includes the edge 92 of the airfoil skin 94 plus the taper gap 138 for the first cladding layer 130 . Thus, where adjacent the rib 28 , the bonding surface 90 includes the airfoil skin 94 plus the taper gap 138 of the immediately prior cladding layer 10 . Still using the second cladding layer 134 as the example, the widening of the energy beam for each layer may take into account the increased surface area of the instant bond surface 90 , as well as the taper angle 136 within the instant bond layer, to ensure proper bonding of the cladding layer 10 to the tapered side surface 44 at both the upper surface 140 at a lower surface 142 of each cladding layer 10 . While a constant taper angle 136 is shown, the taper angle 136 may vary at one or more cladding layers 10 . The taper gap 138 may be filled in by the cladding layer 10 in a manner that creates any geometry desired, such as a stress reducing fillet, or other such feature.
In an embodiment the taper angle 136 may be selected to cooperate with a positioning of the energy beam source 102 and scanning optics 104 such that both sides of one rib 28 may be accessed by the energy beam 100 without having to translate the energy beam source 102 . In other words, energy beam source 102 and scanning optics 104 may be positioned such that the energy beam 100 can jump to both sides of the rib 28 through the scanning optics alone and still have line-of-site access to the areas adjacent both tapered side surfaces 44 of the rib 28 . This arrangement enables the energy beam 100 to move both melt pools past the rib 28 simultaneously and uninterrupted, while forming the proper bonds at the junctions 70 .
The taper angle 136 may be selected to create an angle of incidence 144 between the tapered side surface 44 and the energy beam 100 . This is effective to impart more heat to the tapered side surface 44 which, in turn, improves a bond between the tapered side surface 44 and the cladding layer 10 . The angle of incidence 144 may be the same for both sides of the rib, or it may be different, depending on the local requirements.
While FIGS. 2 and 3 shown the energy beam 100 processing adjacent a tapered side surface, it may still be possible to fuse the cladding layer 10 to the untapered side surface 42 when the angle of incidence 144 is zero. (I.e. when there is no direct impingement of the energy beam 100 on the untapered side surface 42 ). In this case the local plasma and available superheat contained in the molten pool may be sufficient to achieve such lateral melting and fusion. Consequently, the cladding layer 10 may be bonded to all instances of adjacent rib side surfaces.
FIG. 4 schematically shows an exemplary embodiment of patterns followed by the energy beam 100 when forming the cladding layer 10 . In this view the patterns are superimposed on the cladding layer 10 , which rests on the substrate 12 . In this exemplary embodiment the energy beam is guided in a circular pattern 150 . A thickness 152 of the airfoil skin 94 , and hence the cladding layer 10 may be 3.0 mm. A diameter 154 of the circular pattern 150 may be 3.5-4.0 mm and adjacent circular patterns 150 may overlap by approximately 1 mm as the energy beam traverses the second path 52 . The energy beam may have, for example, a 1 mm diameter. In this exemplary embodiment the first rib material 30 is not tapered. Consequently, the circular pattern 150 need not increase in diameter when adjacent the first rib material 30 to ensure the cladding layer 10 bonds to the untapered side surface 42 . In contrast, the second rib material 32 is tapered. The scanning optics 104 may adjust from the circular pattern 150 to a more oval pattern 156 when the pattern is adjacent the second rib material 32 in order to ensure the cladding layer 10 bonds to the tapered side surface 44 . In a non limiting exemplary embodiment there may be a first oval pattern 156 with long sides 158 separated from each other by 2 mm adjacent an overlapping second oval pattern 160 with long sides 158 likewise separated from each other by 2 mm. The result is a near uniform coverage of the bonding surface 90 , which includes the edge 92 of the airfoil skin 94 and the taper gap 138 .
To form the additional rib section 24 , the pattern 150 may be moved from the pressure side wall 16 to the suction side wall 18 (or the opposite direction, depending on the path chosen). Alternately, when the energy beam reaches the additional rib section the same widening of the energy beam that occurs in FIG. 4 may also occur, but where the pattern widens such that the long sides 158 span the pressure side wall 16 and the suction side wall 18 to form the entire additional rib section 24 . This may require significant power, for example, 8-10 kW, but may expedite production where possible. Here again the exemplary embodiment is not meant to be limiting. The exact patterning may be tailored in ways known to those of ordinary skill in the art. For example, the energy beam could travel in a straight line back and forth between the pressure side wall 16 and the suction side wall 18 , advancing one beam diameter after each pass.
FIG. 5 schematically shows an exemplary embodiment of a pattern followed by the energy beam while forming an exemplary embodiment of a tip cap 170 of the airfoil 80 , which may be necessary to complete the airfoil 80 . An interior of the airfoil 80 may be filled with a ceramic material (e.g. zirconia, silica, alumina, titania, graphite, dry ice etc) in powder or solid form and the ceramic material may be positioned to surround an exterior of the airfoil 80 . The powder material 106 is positioned on the ceramic material that fills the airfoil 80 . In an exemplary embodiment the energy beam traverses a circular pattern 150 back and forth between the airfoil pressure side 82 and the airfoil suction side 84 . Once the tip cap 170 is complete the ceramic material may be removed, leaving a completed airfoil 80 . This exemplary embodiment is not meant to be limiting. The exact patterning may be tailored in ways known to those of ordinary skill in the art.
In a variation shown in FIG. 6 , the energy beam may form the tip cap 170 in a different manner. Instead of forming distinct lateral deposits, the energy beam may be widened so that the melt pool travels from the airfoil leading edge 86 to the airfoil trailing edge 88 . This may require significant power, for example, 8-10 kW, but may expedite production where possible. This exemplary embodiment is not meant to be limiting and other patterns may be used, such as a pattern similar to the overlapping, wide oval patterns that span from the airfoil pressure side 82 to the airfoil suction side 84 disclosed above.
From the foregoing it can be seen that the inventors have devised an innovative method for building up an airfoil in a manner not previously possible. Consequently, this represents an improvement in the art.
While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.
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A method, including: providing a layer of powder material ( 106 ) on a substrate ( 12 ) having protruding rib material ( 26 ); and traversing an energy beam ( 100 ) across the layer of powder material to form a cladding layer ( 10 ) around and bonded to the protruding rib material, wherein the cladding layer defines a layer of an airfoil skin ( 94 ).
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FIELD OF THE INVENTION
This invention is concerned with a uniform distribution and mixing apparatus to mix two distinct phases, one a liquid and the other a gas. These types of devices have historically been important in passing a dual phase mixtures to heat exchangers in many industries including the chemical and oil refining industries.
BACKGROUND OF THE INVENTION
A multistage reactor including a vertical column is disclosed in U.S. Pat. No. 3,642,452 (Tarbourich). A bundle of vertical tubes serve the ascent and descent of liquid. Pipes arranged in coaxial relation with respect to said tubes carry gas and a down tube is provided for better mixing of the phases.
Many prior art patents have discussed many means to mix two phases. In U.S. Pat. No. 3,452,966 (Smolski) liquid such as water is mixed with air via an open-ended vertical tube. The lower end of the tube is submerged in the liquid above a gas bubble generator. A helical baffle is provided to create a turbulence in the tube and assist in adsorption of the gas into the liquid.
In U.S. Pat. No. 3,738,353 (Santoleri) a series of sparger tubes are mounted below a heat exchanger within the confines of a baffle plate. Air bubbles are discharged upward which increases the transfer of heat from a waste-water stream. In U.S. Pat. No. 4,440,698 (Bloomer), a heat exchanger is provided whereby jets are created in the duct through which the gas flows which contacts the exchanger. Liquid is sprayed over the heat exchanger and high velocity jets of gas pick up liquid and carry it into the exchanger.
Finally, U.S. Pat. No. 5,376,311 (DeGuzman) discloses an apparatus for the aeration of liquids by passage of a gas through a porous diffuser thereby producing microsized bubbles dispersed in the liquid. A porous tubular member is provided in approximately the center of the apparatus.
BRIEF DESCRIPTION OF THE INVENTION
This invention is an apparatus for uniform distribution and mixing two phases together using a partitioned vessel having means for the inlet of gas and liquid to the vessel. Liquid enters the vessel, which is vertical in orientation, at a point in elevation higher than the gas inlet. The liquid and gas mix in the channels or tubes which are vertically orientated in the vessel, through an aperture in tubes for the ingress of liquid to the gas stream moving through the channels or tubes. It is preferred but not required that the vessel communicate with the tubeside of a shell and tube heat exchanger.
DETAILED DESCRIPTION OF THE INVENTION
In heat exchangers, the disproportionate flows and improper mix of vapors and liquid greatly affects performance. An improper mixture of gas and liquid in a heat exchanger has a negative influence on refinery operations. Tubes that become deficient in liquid tend to dry out and foul, which leads to a reduction in heat transfer rates. It also adds greatly to maintenance tasks.
In addition, conventional distributors can produce a relatively non-uniform distribution of liquid and thus are more sensitive to minor variations in heat exchanger orientation. Good liquid and gas distribution is particularly important where relatively small temperature differences exist between the hot and cold streams that exchange heat with each other in the heat exchanger.
This invention acts to insure uniform admixture of gas and liquid. This invention establishes a mixed stream that can be used in the tubeside of shell and tube heat exchangers. Instead of premixing liquid and gas in a single plenum below the exchanger and, then passing that admixture through a perforated plate, the apparatus described herein mixes the gas and liquid through apertures in vertically orientated channels or tubes.
The apparatus herein described is situated in a vertical orientation with respect to the horizon. The vessel is partitioned on the inside and has side walls, a bottom and a top. A gas inlet is provided at the bottom of the vessel. Gas may enter directly into the vessel, or as a preferred embodiment, the gas may accumulate in a plenum chamber having a solid plate defining the top of the plenum chamber interrupted only with apertures for the passage therefrom of the gas through one or more vertical tubes.
A liquid inlet means is also provided which is preferably located in elevated position with respect to the gas inlet and, if existent, the plenum chamber. The liquid inlet permits liquids, such as treated water or hydrocarbon liquids, to enter the vessel and be confined therein between the top of the plenum chamber (bottom) and the top part of the vessel. It is desirable that the liquid level be maintained at a level lower than the top of the vessel. The liquid level must however be maintained above the elevation of perforations or apertures in the channels wherein gas is being passed from the plenum chamber.
In a preferred embodiment of this invention, a liquid distribution plate may be situated above the top of the plenum chamber and below the level of the apertures in the tubes. The plate is equipped with multiple selectively sized and situated perforations or apertures to provide a uniform liquid level in the vessel at a point above the liquid distribution plate.
A hollow channel, or multiple channels, are provided for the passage of gas which mixes with the liquid. These channels are also referred to herein as tubes and will preferably have a circular cross section. However, any other cross-section can also be used such a square, rectangle or triangle. These tubes interconnect and communicate with the gas inlet or plenum chamber. Each tube contains one or more apertures to admix the gas with the liquid. As set forth above, the liquid level must be above the aperture height in order for the liquid to enter the tube to mix with the gas. The aperture or apertures may have any cross-section although circular apertures are preferred for manufacturing purposes. While not a preferred embodiment herein, the apertures on the tubes may be arranged at different heights and it is possible to have multiple apertures at different heights on the same tube.
The top of the vessel is constructed so that the mixture of gas and liquid pass from the vessel to use downstream in a different vessel or environment. The structure of FIGS. 4-6 discussed herein show preferred embodiments concerning passage downstream to other uses but this invention should not be limited to those specific preferred embodiments. And, as shown in FIG. 2, the channel tubes may actually penetrate the bottom of a shell and tube heat exchanger with the gas-liquid mixture in the tubes being used to indirectly cool or heat a liquid or a gas in an exchanger. In this embodiment, the used gas-liquid admixture exits the heat exchanger through an outlet means in the top of the exchanger.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of the mixing apparatus of this invention.
FIG. 2 is a side view of a shell and tube heat exchanger receiving the mixed phase from the apparatus of FIG. 1.
FIG. 3 is a cross section of the apparatus of FIG. 1.
FIG. 4 is a side view of the discharge of the mixed phase from the vessel.
FIGS. 5 and 6 are side views of modifications containing discharge devices not shown in FIG. 4.
DETAILED DESCRIPTION OF THE DRAWINGS
In FIG. 1 a vertical vessel 1 is shown with the necessary elements that comprise this invention although other additional elements that are not integral to the function of the mixing of the two phases are not shown. The vertical vessel is partitioned to accomplish the mixing of the two phases. The vessel comprises side walls 3, bottom 5 and top 7. The bottom of the vessel 5 communicates with a gas inlet 9 for the flow of gas into the vessel. In a preferred embodiment, gas inlet 9 communicates with the interior of the vessel through a plenum chamber 11 having a top plate 13 which extends from each side wall 3. The gas chamber is designed to provide uniform flow of gas to all tubes 15. Top plate 13 is imperforate with the exception of at least one, and preferably more, tubes 15 openly communicate with the plenum chamber and the upper portion of the vessel. Thus, gas rises from the inlet means 9, to the plenum chamber 11 and then through tubes 15 for eventual admixture with a liquid phase.
Tubes 15 may be any length as long as they extend to a point above the level of liquid 17 which may vary in different vessels which are used for mixing different phases. As a corollary, an open space 19 of varying height is provided intermediate the liquid level 17 and the vessel top 7.
A liquid inlet is provided in the vessel for the flow of liquid into the vessel which is to be mixed with the gas in tubes 15. The liquid is segregated from plenum chamber 11 and is situated in the vessel at an elevated height with respect to either plenum chamber 11 or gas inlet 9 via imperforate plate 13 and tubes 15 which seal the apertures in the otherwise solid plate 13. Liquid passes into vessel 1 to form a liquid reservoir 21 having a level shown at 17. In a preferred embodiment, the liquid is evenly distributed to the vessel interior via a liquid distribution plate 23 having select predetermined perforations therein for the controlled passage of liquid to liquid reservoir 21. Distribution plate 23 must be positioned above (or higher than) liquid inlet 19.
Gas passes upwardly through tubes 15 and mixes with liquid entering via apertures 25 situated in tubes 15. Apertures 25 in tubes 15 are located in the tubes at a height above liquid distribution plate 23 and below the level of liquid 17 in vessel 1. The apertures 25 may comprise any number of openings in the form of a large number of pin hole openings to one opening specifically sized to enhance the mixing of the two phases. Liquid passes from the liquid reservoir to the interior of tubes 15 via apertures 25. In this manner, the two phases are admixed immediately upstream of use in a vessel, such as a heat exchanger in another vessel surmounted to vessel 1.
FIG. 2 shows a shell and tube heat exchanger 101 which is situated immediately above mixing vessel 1. The top 7 of vessel 1 forms the bottom of heat exchanger 101. Top 7 is imperforate with the exception of openings for passage of tubes 15 into the exchanger. The connection of the tubes with top 7 are sealed on the top and bottom of top 7 via any conventional means such as welding. Exchanger 101 is equipped with inlet means 103 and outlet means 105 for the passage of shellside fluid into and out of the exchanger. The fluid entering the exchanger indirectly contacts the mixed phases from vessel 1 via tubes 15 and thereby either cools or heats the fluid to the desired level of temperature. The mixed phase of fluids passing through tubes 15 in vessel 101 exits the exchanger through outlet means 107 which communicates with a collection space 109 which does not communicate with the shellside fluid that is being cooled or heated in exchanger 101.
FIG. 3 shows a cross section of vessel 1 wherein tubes 15 rise above distribution plate 23 and liquid is supplied to the liquid reservoir 21 via perforations 27 in plate 23.
FIG. 4 is a side view of the upper portion of vessel 1 and the lower portion of vessel 101. This configuration is a preferred means of passing the mixed phases to a surmounted heat exchanger. Tubes 15 penetrate top plate 7 thereby passing the mixed phase from vessel 1 to vessel 101 for use therein however, the area above and below plate 7 do not communicate with one another.
FIG. 5 shows via a side view, tubes 15 ending or terminating immediately below top plate 7. A second set of tubes 15A is positioned above and juxtaposed to the terminus of tube 15 for passage of a gas/liquid admixture from tube 15 directly into tubes 15A, located in vessel 101. FIG. 6, via a side view, shows another configuration whereby tubes 15A from vessel 101 penetrate the top 7 of vessel 101. The bottom of tubes 15A are equipped with with flared inlet, 201. These flares may extend from the ends of tube 15A or from plate 7. If a line is drawn of the angle that flare 201 makes with the plate, that angle is less than 90°.
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A device is provided for mixing two fluids, one a liquid, the other a gas, where apertures are provided in channel tubes to mix the fluids in the individual channels. The mixing device provides a two fluid admixture for passage to downstream processing, most preferably the tubeside of a shell and tube heat exchanger. The vessel is equipped with a gas inlet means located below a liquid inlet means with respect to the height of the vertical vessel. A distributor plate is situated substantially perpendicular to said channel or channels at a point in said vessel below said apertures for influx of the liquid into the gas phase. The apparatus provides uniform distribution of gas and liquid to all parallel channels.
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[0001] This application claims priority of provisional patent applications: Ser. No. 60/612,587 filed Sep. 23, 2004; Ser. No. 60/644,708 filed Jan. 18, 2005; and Ser. No. 60/653,262 filed Feb. 15, 2005 which are each herein incorporated in their entirety by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a vehicle wash station.
[0003] An important part of a clean environment is to maintain bodies of water, such as lakes, rivers, etc. free of undesirable aquatic plants, animals, fish, or water related material.
[0004] Despite precautions, bodies of water have become contaminated with undesirable animals, larvae, eggs, or plants. Since marine vessels are continually moved between bodies of water, one form of spread of contamination is the transfer of a marine vessel, such as a boat and/or its trailer, from one contaminated body of water to another. Minute plants, animals, fish, and debris, such as mud containing such plants, animals, etc. adhere to the marine vessel or trailer. To prevent the transfer of undesirable aquatic life from a contaminated body of water to a non-contaminated body of water, it is necessary that any portion of a marine vessel and that came into contact with the contaminated water be rinsed clean of such water and any water carried contaminants.
[0005] While hoses can be used at lake launch or entry ramps, the water is typically at ambient temperature as it was drawn from the body of water. Further, it is difficult to completely rinse all underside portions of the trailer and vessel, while standing on one side or the other of the trailer.
[0006] Thus, what is needed is a wash apparatus which can be employed at boat launch ramps on bodies of water to assure that any contaminants from the body of water are rinsed free of the marine vessel and its trailer.
[0007] Besides watercraft, it would also be desirable to provide a wash station which can be used to wash equipment or vehicles at construction, land-management, environmental, agriculture, as well as nautical sites. Besides cleaning such equipment or vehicles by removing dirt and other debris picked up at the site, it would also be desirable to provide a means for preventing the transfer of toxins, fertilizers or other biological or chemical components from one site to another as the equipment and vehicles are moved from site to site.
SUMMARY
[0008] It is the intent of the present invention to address the aforementioned concerns. In one aspect of the invention, a portable wash station is provided for a vehicle including motorized vehicles or trailered apparatus, such as a watercraft which is pulled by a tow vehicle. The portable wash station includes a wash housing positionable on a boat ramp. The wash housing has a platform with a plurality of nozzles therein for directing fluid, such as water or cleaning solution to an underside of the trailered apparatus. The nozzles are fluidly connectible to a source of water. The portable wash station also includes at least one drive-up approaching ramp for directing the tow vehicle and the trailered apparatus to the wash housing.
[0009] In another aspect of the invention, the portable wash station further includes a control unit communicating with the wash housing for activating water delivery to the nozzles during a wash cycle. The control unit may also include means for distinguishing the trailered apparatus from the towed vehicle and means for actuating the water delivery to the nozzles only when the trailered apparatus is on the platform.
[0010] In yet another aspect of the invention, the control unit may include a payment system for authorizing activation of the water delivery to the nozzles.
[0011] Further, the portable wash station may include a clean water reservoir and a pump for directing clean water in a reservoir to the nozzles. A heating system for heating the clean water before directing the clean water to the nozzles may be included in the wash housing.
[0012] In addition, the portable wash station may include a flush port or drain for directing waste water away from the platform. The flush port or drain may be connected to a waste reservoir which captures the waste water in the wash housing. The wash housing may further include filtration means for cleaning the waste water and also include means for recirculating the filtered water back to the nozzles.
[0013] In yet another aspect of the invention, the portable wash station includes a pair of outboard spray towers positionable on lateral sides of the platform wherein each tower includes at least one spray nozzle directed to the opposing tower. The towers may be spring-loaded for selectively allowing each tower to collapse. The wash housing may include at least one recess for receiving each tower for storing the towers during transport.
[0014] In yet another aspect of the invention, the controlling unit may be housed in one of the towers.
BRIEF DESCRIPTION OF THE DRAWING
[0015] The various features, advantages, and other uses of the present invention will become more apparent by referring to the following detailed description of drawing in which:
[0016] FIG. 1 is a perspective view of one aspect of a wash station;
[0017] FIG. 2 is a perspective view of another aspect of a wash station;
[0018] FIG. 3 is a perspective view of another aspect of a wash station;
[0019] FIG. 4 is a perspective view of a modified aspect of the wash station shown in FIG. 3 ;
[0020] FIG. 5 is a perspective view of the wash station shown in FIG. 1 depicting the cleaning of a watercraft;
[0021] FIG. 6 is a perspective view of the wash station shown in FIG. 1 depicting the use of the spray wand to clean a watercraft;
[0022] FIG. 7 is a perspective view of the wash station shown in FIG. 1 depicting the use of both wands and a flushing gear attachment on one of the wands to clean portions of a watercraft;
[0023] FIG. 8 is a perspective view of another aspect of the wash station shown in FIG. 1 ;
[0024] FIG. 9 is a perspective view showing the transport and storage position of the wash station shown in FIGS. 4 and 5 ; and
[0025] FIG. 10 is perspective view of another aspect of the wash station.
DETAILED DESCRIPTION
[0026] Although the following description of one example of a wash station described in conjunction with FIGS. 1 and 2 is cleaning watercraft and/or trailers for watercraft, it will be understood that the present wash station may also be employed in other applications to clean other vehicles or equipment, such as construction, land management, environmental or agricultural equipment and/or vehicles and towing trailers for such equipment.
[0027] One aspect of a self-contained, transportable wash station 10 that can be placed and set-up at use sites, such as water access sites for example, is shown in FIG. 1 . The wash station 10 includes a wash platform 12 with an incorporated water-collecting basin design formed of inward angled plates 13 and 14 which tend to assist in centering the wheels of a towing vehicle and a marine vessel trailer as the vehicle and trailer are driven along the wash platform 12 . Side fold out or stationary clean water tanks 16 and 18 are plumbed to two outboard spray towers 20 and 22 and to platform spray nozzles 24 which may be mounted laterally across the platform 12 . A tank-less water heating system 25 is plumbed serially with a motor-pump 27 , and prior to the spray nozzles 24 . Additional spray nozzles 24 may be mounted in each spray tower 20 and 22 . Each tower 20 and 22 , approximately four foot high, by example, can be stowed for transportation in a recess pocket 26 and 28 , respectively, incorporated in the side clean water tanks 16 and 18 . For set-up, the spray towers 20 and 22 are unlatched and positioned vertically. The towers 20 and 22 are spring loaded, in one direction, or two opposed directions, allowing for storage during transporting and to allow the independent towers 20 and 22 to collapse if the tow vehicle or trailer should come into contact with the tower 20 and 22 during movement through along the platform 12 in one or either direction. Thus, the towers 20 and 22 may also be spring loaded for bi-directional swinging movement, shown in FIG. 3 , instead of the single spring loaded direction movement shown in FIG. 1 . Alternately, the towers 20 and 22 maybe removably mounted on the platform 12 by bolts, etc. so as to be removed and shipped loose on the platform 12 .
[0028] In addition, the spray nozzles 24 may include a high pressure wand 200 having one or more discharge nozzles at one end, as shown in FIG. 3 . The fluid applicator may optionally include a so-called “flushing ear” which is connected to the fluid or water supply and has an attachment which can be coupled to the motor outdrive. This enables clean water to be pumped through the watercraft motor coolant system to remove any aquatic nuisances which may have been picked up during operation of the watercraft.
[0029] The wash station 10 is equipped with low inclined ramps 30 and 32 at one or both ends of the wash platform 12 for the tow vehicle and trailer ascent and descent. Alternately, the two ramps 30 and 32 at each end can be replaced by a single large ramp. The ramps or 30 and 32 may be removable from the wash platform 12 or pivotally hinged to the wash platform 12 .
[0030] The clean water tanks 16 and 18 are equipped with appropriately placed locking fill and flush ports 34 and 36 , respectively. The wash platform 12 houses the closed motor-pump 27 , a power supply 29 , such as a battery or batteries. These are placed subsurface, under the basin near the end of the platform 12 . Secured access covers protect the motor and pump.
[0031] An enclosed fuel tank 38 located within the platform 12 provides fuel to power the motor 27 . The fuel can be any suitable fuel for powering the motor 27 . For example, propane gas, natural gas, diesel, or gasoline may be employed. Further, if a source of electricity is located near the use site of the wash station 10 , the motor 27 can be an electric motor coupled to the electric power source thereby eliminating need for use of fuel in the fuel tank 38 .
[0032] Solar powered collectors, batteries, fuel cells, and an electric motor may also be employed, again depending upon the location of the use site of the wash station 10 .
[0033] The platform 12 is the structure that incorporates the recovery tanks 40 , capturing the used water and the contaminants that are sprayed off of the watercraft hull and trailer. Easy access flush ports 36 are placed on the platform 12 allowing for the pumping, draining and flushing of the recovery tanks 40 .
[0034] All operating directions are appropriately placed on either or both of the towers 20 and 22 and safety reflectors may be adequately placed around, and on the wash station 10 . The wash station 10 is appropriately painted and utilizes weather resistant construction materials and design methodology.
[0035] Although not shown, a handrail may be positioned above the platform 12 and mounted to the platform 12 by mounted legs.
[0036] Alternately, or in combination with the handrail and legs, a side splash curtain formed of plastic, for example, can optionally be mounted on the longitudinal side edges of the platform 12 to contain splash. The upper surface of the curtain or a frame containing the curtain may function as a handrail.
[0037] With the use of an issued magnetic swipe card, bar coded cards or other payment token and a matching reader, an electronic network authorizes the wash cycle by the wash station 10 . Photocell transmitters and receivers or proximity sensors 42 mounted on the towers 20 and 22 , for example, measure the watercraft length for starting and stopping the wash cycle. All electronic circuits and wiring are contained on the interior of the wash station 10 within a weather and water resistant housing. The swipe card system offers a money free activation eliminating any concerns of securing money at remote sites during unpopulated times. Swipe cards may be issued through local authorities along with watercraft registrations or at any predetermined authorized distributor. Swipe cards may be issued or purchased by watercraft owners. Local authorities can monitor the wash station use through the swipe card system and enforce governing laws.
[0038] After set-up of the wash station 10 , the clean water tanks 16 and 18 are filled with clean water and the motor 27 is fueled. The electronic system is then activated, followed by priming of the plumbing system. The tow vehicle operator approaches the wash station 10 with his or her vehicle and trailer in-line. Driving up the approach ramps 30 and 32 , the driver stops at the tower 20 and swipes the assigned swipe card, activating the wash cycle. After swiping of the card, the photocell transmitters and receivers 42 read that the tow vehicle is between the towers 20 and 22 . When the tow vehicle proceeds forward, the photocells 42 read the end of the tow vehicle to start the wash cycle.
[0039] A fixed or oscillating, high pressure, multi-directional spray pattern is created from the tower and platform spray nozzles 24 . This predetermined spray pattern maximizes the direction of heated clean water onto the watercraft and trailer in order to remove most, if not all infectious aquatic nuisances. The driver proceeds forward, pulling the watercraft through the wash station 12 . When the watercraft passes completely through the towers 20 and 22 , the photocells 42 read the open clearance causing termination of the wash cycle. The majority of the water that is sprayed onto the watercraft drops onto the platform 12 where it is then directed by the platform basin design and collected in the recovery water tanks 40 .
[0040] All of the components of the wash station 10 are formed of weather resistant materials and construction. The platform 12 is easily transportable to any use site by a trailer or truck, as shown in FIG. 9 .
[0041] In using the swipe card, the control in the master tower 20 may also be connected by wireless communication, hard line, etc. through a network to a central location to enable monitoring of the operation of the wash station 10 .
[0042] It will also be understood that other means for authorizing use of the wash station by individual watercraft owners may also be employed. For example, conventional currency or paper money acceptance devices may be mounted on the platform 10 or the tower 20 , such as on the master tower 20 , for accepting currency and bills to enable operation of the wash station 10 .
[0043] In another aspect shown in FIG. 2 , a wash station/housing 100 is devised as a portable unit that will be placed and set-up at water access sites. The wash station 100 consists of two major components, a control unit 102 and a spray nozzle 104 . The control unit 102 houses a swipe card panel 104 , a motor and pump assembly 106 , tank-less water heater 108 , water filter system 110 and electrical components. The wash station 100 includes a ground placed, low profile housing 105 in which the spray nozzles 104 are contained. The wash station 100 is positioned and anchored at a water access ramp just above the water surface. Wash 100 are able to accommodate various ramp widths by connecting multiple stations 100 together with an end-to-end connection design.
[0044] Plumbing for the wash station 100 consists of a water body draw line 120 . The end of the draw line 120 contains a valve 121 , which is placed in the actual body of water. The draw line 120 feeds water to the control unit 102 where the water is screened for large elements and filtered for finer particles. This clean water is pumped, heated, and fed to the wash station 100 where it is ejected upward through the spray nozzles 114 .
[0045] The wash station 100 is appropriately designed for watercraft trailers to cross over it during removal of watercraft from a body of water.
[0046] With the use of an issued swipe card through a reader, an electronic network authorizes a wash cycle. All electronics and wiring are contained on the interior of the control unit 102 . The swipe card system 104 offers a money free activation, eliminating any concerns of securing money at remote sites during unpopulated times. Swipe cards may be issued through local authorities along with watercraft registrations or at any predetermined authorized distributor. Swipe cards may be issued or purchased by watercraft owners. Local authorities can monitor the wash station use through the swipe card system and enforce governing laws.
[0047] After set-up, the wash station 100 is ready for use. The wash station 100 is designed to be used when watercraft are leaving the water on a trailer. After the watercraft is loaded on the trailer, the tow vehicle driver uses the issued swipe card to activate the cycle. The wash commences and terminates through a photo mass sensor 122 on the control unit 102 reading the vehicle position. The tow vehicle proceeds forward pulling the watercraft and trailer through the water spray. The ejected wash consists of a fixed, spray pattern created from the nozzles 104 . This predetermined spray pattern maximizes the direction of heated clean water onto the watercraft and trailer in order to remove most, if not all of infectious aquatic nuisances. The clean water that is sprayed onto the watercraft and trailer flows back into the original body of water.
[0048] All of the components of the wash station 100 are designed of weather resistant materials and utilize durable weather resistant construction.
[0049] The motor, pump, and water heater system may be powered by any suitable fuel, including propane gas, natural gas, diesel, gasoline, etc. stored in a tank in the control unit 102 . The motor, pump, and heater system may also be electrically powered from an electrical power source, such as batteries, solar power collectors, fuel cells, or hard wired to a local source of electric power.
[0050] Refer now to FIG. 3 , there is depicted another aspect of a wash station 202 .
[0051] The wash station 202 includes a base or enclosure 204 which may be mounted above, below or partially below ground surface for a permanent installation. It will be understood, however, that the base 204 may also be provided as a transportable, self-contained structure.
[0052] In an above-ground installation, one or more inclined ramps, such as ramps 231 and 233 may be provided at one or both ends of the base 204 to allow bi-directional access of equipment or vehicles to the wash station 202 . The ramp or ramps 231 or 233 may be fixed, pivotally hinged or removably attachable to the base 204 .
[0053] A wash platform 212 is formed on the upper surface of the base 204 and provided with a water-collection basin design formed of inward angled plates 213 and 214 which tend to assist in centering the wheels of a towing vehicle or a piece of equipment on the base 204 as the vehicle or equipment is driven along the wash platform 212 .
[0054] One or more drains 215 are formed on the wash platform 212 and receive water from the plates 213 and 214 . The drains 215 open to the hollow interior of the base 204 . In a permanent installation of the wash station 202 , an outlet 216 is formed in the base 204 and establishes fluid communication between the interior of the base 204 and a water outlet conduit or pipe 218 . The outlet pipe 218 may be connected to any water drainage system, including a private or municipal septic tank, city sewer, separate storage tank, etc.
[0055] One or two side-foldout or stationary spray towers 220 and 222 are mounted on the base 204 , intermediate the opposite longitudinal ends of the base 204 . Each spray tower 220 and 222 may be spring biased for folding movement in one or two opposed directions to enable the spray towers 220 and 222 to move out of the way in the event that either spray tower 220 and 222 is contacted by the equipment or vehicle as the equipment or vehicle moves across the wash station 202 .
[0056] The spray towers 220 and 222 may be identical or provided with different fluid application devices. Stationary and/or oscillating spray nozzles 223 may be provided on each spray tower 220 and 222 and laterally across the base 204 . Alternately, the high pressure wand 200 , described previously, may be mounted in one or both of the spray towers 220 and 222 to enable the user to apply water to any location of the equipment or vehicle on the wash station 202 .
[0057] A flushing ear may be provided in at least one of the spray towers, such as spray tower 222 , for connection to a watercraft motor outdrive for flushing of the motor coolant system.
[0058] Automatic actuation determination devices, such as one or more photocells 224 , may be mounted on one or both of the spray towers 220 and 222 . The photocells 224 activate the water supply system in the wash station 202 upon detecting a forward end of a vehicle or piece of equipment on the wash platform 212 . The photocells 224 also detect the passage of the entire length of the vehicle or piece of equipment beyond the spray towers 220 and 222 to terminate the application of water to the spray devices in the spray towers 220 and 222 at the proper time.
[0059] An actuation means 226 may be provided for the wash station 202 to enable operation of the wash cycle. As described above, a swipe card reader for acceptance of credit cards magnetic stripe cards, a currency receiving unit a bar code reader for a card carrying a bar code, or simply a pushbutton or key actuated, lockable on/off switch may be provided on at least one of the spray towers 220 or 222 to enable activation of a wash cycle.
[0060] Any of the wash stations 10 and 202 and the wash station 100 may include wireless communication transceivers for remotely reporting wash station operation, credit card validation, etc. to a central station.
[0061] As shown in FIG. 3 , for a permanent installation of the wash station 202 , electrical service is provided to the electrically actuated components of the wash station 202 by connection with electrical power service conductors 230 at the site where the wash station 202 is located. The conductors 230 may be permanent, hard wired conductors from an electrical power source.
[0062] The conductors 230 are connected to components in the wash station 202 , typically mounted within the interior of the base 203 in a water sealed compartment. Such components include a motor pump unit 232 and an optional water heater 234 . A fuel tank 236 may also be mounted within the base 204 to supply fuel to the motor/pump unit 232 . Alternately, the motor/pump unit 232 may be an electrically operated motor/pump unit 232 which receives power from the electrical service conductors 230 . The conductors 230 are also connected to the photocell 224 and the activation unit 226 on at least one of the spray towers 220 or 222 .
[0063] As an option to merely discharging all used water drained through the drains 215 and the interior of the base 204 to the sewer or septic tank during each wash cycle, the wash station 202 may be provided with filters, such as a UV filter, a particulate filter, etc. or a water filtration unit and pump which enables some or all of the water collected in the base 204 during a wash cycle to be filtered and recycled as relatively clean water for the next wash cycle. The recycled water can be coupled in parallel to a fresh water inlet 240 which may be connected to a private or municipal water supply system. The fresh water inlet 240 may be used by itself to supply water to the spray towers 220 and 222 when the water filtration and recycled components are not provided in the wash station 202 .
[0064] The same filters could also be employed in the portable wash station 10 and the wash station 100 to clean the water before it is discharged back into the body of water or surrounding soil.
[0065] Referring now to FIG. 4 , there is depicted a modified wash station 260 which contains modifications to the wash station 202 described above and shown in FIG. 3 . The wash station 260 includes a base 204 which acts as a recovery tank for waste water drained through the upper surface of the base, as described hereafter, during a vehicle or watercraft cleaning cycle.
[0066] Since the base 204 and the entire wash station 260 is intended for below or partially below ground surface mounting as a permanent installation at a wash site, the base 204 may be provided as a separate transportable structure, apart from the reminding elements of the wash station 260 .
[0067] A wash platform 262 is mounted on the base 204 and includes a pair of laterally inward inclined plates 264 and 266 . The plates 264 and 266 extend laterally inward from both ends of the base 204 and incline from both ends, inward to opposed center edges 268 and 270 , respectively, which may be covered by a grate or mesh to form a drain opening 269 to the interior of the recovery tank within the base 204 . Each plate 264 and 266 also includes a laterally extending grate 272 and 274 which also opens to the interior of the base 204 .
[0068] A pair of end access plates or panels 276 and 278 are also mounted on the base 204 and incline downward from the longitudinal ends of the base 204 as shown in FIG. 4 . The side edges of each access panel 276 and 278 may be fixedly joined to the mating side edges of the inclined panels 264 and 266 or formed separately therefrom. At least one of the access panels, such as access panel 278 , may be pivotally mounted on the base 204 to allow access to a waterproof, sealed compartment within the base 204 which houses the incoming electrical power lines 230 , freshwater inlet conduit and conduit connections 240 , water recycling filters 280 , an electrical motor-pump unit 232 and the water heater 234 .
[0069] It will be understood that the grates 269 , 272 , and 274 may open to a collection chamber in the base 204 which is connected by a pipe or conduit to the filters 280 . The motor-pump unit 232 serves to draw water draining through the grates 269 , 272 , and 274 and the interconnecting conduit through the filters 280 and then on to the water heater 234 for reapplication via suitable conduits, not shown, to the spray nozzles 223 , wands 200 , or other water discharge devices provided on the wash station 260 .
[0070] An inclined ramp 284 is provided on one end of the base 204 . A second inclined ramp 286 may also be provided on the opposite end of the base 204 . The ramps 284 and 286 may each be formed of a single member or individual ramp sections, each removably or fixedly attached to one end of the base 204 .
[0071] The spray towers 220 and 222 are identical to the spray towers employed in the wash station 200 shown in FIG. 3 and, as such, will not be described further. It will be understood that clean water may be discharged from the spray tower 220 and 222 and through the nozzles 223 mounted vertically in each spray tower 220 and 222 and/or through nozzles 223 spaced laterally across the inclined plates 264 and 266 on the base 204 for thorough cleaning of any surface on a vehicle or watercraft disposed on the wash platform 262 or moving slowly across the wash platform 262 .
[0072] Further, the spray towers 220 and 222 include suitable actuation means 226 which may include all of the various actuation options described above and shown in FIGS. 1-3 .
[0073] In addition to providing electrical power through the power line 230 to the motor-pump unit 232 , the water heater 234 and the circuitry in the spray towers 220 and 222 for operating the photocells 224 and the wash cycle actuation means 226 , other sources of electrical power, such as on board or adjacent disposed fuel cells, motor-generators, solar powered battery units, etc. may also be employed.
[0074] In operation, water drained through the grates 269 , 272 , and 274 during a wash cycle will be routed through the filters 280 and the water heater 234 back to the nozzles 223 and the pressure wand 200 or the flushing ear for reapplication to the same or different vehicle or watercraft.
[0075] Waste water from a cleaning cycle may be temporarily stored in the interior of the base 204 of the wash station 260 and cleaned, optionally heated, and then supplied to the spray devices only when needed.
[0076] The various uses of the wash station described above can be better understood by referring now to FIGS. 5, 6 , and 7 .
[0077] Although the following description will be provided specifically with reference to the wash station 202 shown in FIG. 2 , it will be understood the same principles of operation apply equally to the other wash stations described herein.
[0078] It will also be understood that although a watercraft, such as a boat 300 mounted on a wheeled trailer 302 attached to a towing vehicle, such as a motor vehicle 304 , shown on the wash station 260 , the same wash station 260 , without any or any significant modification, can also be used to clean other watercraft, and other vehicles, such as construction equipment, etc.
[0079] In a typical wash cycle, the towing vehicle 304 will drive up the ramps 231 and 232 and across the wash platform 212 . The photocells in the spray towers 220 and 222 will detect the passage of the towing vehicle 304 therepast and then the presence of the forward end of the watercraft 300 to initiate the wash cycle. The drive means, such as the motor-pump 232 will be activated to pump clean water through the discharge nozzle 223 extending vertically along both of the spray towers 220 and 222 and upward from the laterally spaced nozzles 223 in the wash platform 212 of the wash station 202 . This spray pattern as shown by reference number 306 covers substantially all of the exterior surface of the watercraft 300 and even the trailer 302 .
[0080] FIG. 6 depicts the use of the pressure wand 200 mounted in the spray tower 220 for hand, manual cleaning of an exterior or interior surface of the watercraft 300 . The user can stand on the wash platform 212 or on the ground adjacent to the wash station 202 depending upon the size and shape of the watercraft 300 .
[0081] In FIG. 7 , there is depicted the same hand, manual use of the spray wand 200 along with the connection of the flushing ear 310 mounted in the spray tower 222 to the watercraft motor out drive 312 . The flushing ear 310 enables pressurized, clean, and optionally heated water to be forced through the cooling system of the watercraft motor for flushing of the entire cooling system through a discharge outlet 314 .
[0082] Referring now to FIGS. 8 and 9 there is depicted another aspect of a wash station which will be described primarily in conjunction with wash station 10 shown in FIG. 1 . It will be understood, however, that the following features are also applicable to the wash stations 202 and 260 shown in FIGS. 3 and 4 .
[0083] The wash station 12 shown in FIGS. 8 and 9 is depicted as having the spray towers 220 and 222 described above and shown in FIGS. 3 and 4 and carrying a pressure wand 200 and/or a flushing ear 310 housed within an interior cavity or chamber when not in use.
[0084] Vertically spaced spray nozzles 223 and horizontally spaced spray nozzles 223 are respectively mounted in the spray towers 220 and 222 and laterally across the wash platform 12 . The horizontally spaced nozzles 222 project through grates 320 which may be removably mounted in the wash platform 12 or permanently affixed to a central portion of the wash platform 12 .
[0085] The wash platform 12 , in this aspect includes a multisection base formed of a first central base section 330 and a pair of laterally mounted outboard side base portions 332 and 334 . The central base portion 330 forms a closed chamber having side and end walls which are closed by an upper panel 340 which inclines laterally downward from opposed side edges to a central longitudinal edge and, optionally, from both end walls so as to drain water dripping or deflecting off of a watercraft during a cleaning cycle to flow through the grates 320 and into the chamber or reservoir formed internally within the central base portion 330 .
[0086] A sealed compartment is formed in the central base portion 330 for housing the water heater 25 , the power supply 29 , the fuel tank 38 and the motor-pump unit 27 or other fuel sources, a filtration means 342 which may include UV filters, particulate filters, water filtration unit, etc. suitable piping or conduits, not shown, interconnected between the interior water reservoir chamber in the central base portion 330 through the filter means 342 , the motor-pump 27 and the optional water heater 25 to conduits extending to closed chambers formed in each of the side base portions 332 and 334 .
[0087] The spray towers 220 and 222 are movably mounted in the side base portions 332 and 334 in a permanent fixed manner while being bi-directional swingable in the direction of the arrows for downward movement, substantially flush with an upper surface 344 or 346 of either side base portion 332 and 334 , respectively, during storage or transport of the wash station 12 .
[0088] Fluid connections between the conduits extending from the optional water heater 25 can be of the slide in and/or snap together type.
[0089] Each of the side base portions 332 and 334 is pivotally connected by means of one or more hinges 350 to the adjacent side edges of the central base section 330 . This enables the side base sections 332 and 334 to be pivoted from a deployed, use position shown in FIG. 8 in which the side base sections 332 and 334 are substantially in line with the central base section 330 such that the upper surfaces 334 and 336 together with the upper surface 340 of the central base section 332 form the wash platform to a folded-up, storage and/or transportable position shown in FIG. 9 .
[0090] With the clean water reservoirs in the side base sections 332 and 334 drained of water through suitable drains 320 or flush ports 351 formed on the side or bottom of the side base sections 332 and 334 in the central base section 332 similarly drained of waste water, the side base sections 332 and 334 are pivoted about the hinges 350 to a folded up position overlaying the central base section 330 as shown in FIG. 9 . It will be understood that the spray towers 220 and 222 have previously been folded downward and latched in a substantially flush position with the upper surfaces 344 and 346 of the side base sections 332 and 334 . Alternately, the spray towers 220 and 222 and their respective supporting structure may be physically removed from the side base sections 332 and 334 .
[0091] Suitable latches may be provided to hold the side base sections 332 and 334 in the folded up positions shown in FIG. 9 .
[0092] The ramps 30 and 32 at one or both ends of the wash platform 12 are removed and may be mounted on top of the folded up side base sections 332 and 334 and banded or otherwise latched in place for transport or storage with the remainder of the wash platform 12 .
[0093] As shown in FIG. 9 , wheels 360 may be mounted at one end of the central base section 330 to allow the entire wash platform 12 to be easily moved onto or off of a transport vehicle 362 for transport to or from a use site.
[0094] When the wash platform 12 reaches the use site, the wash platform 12 is unloaded from the transport vehicle 362 . The ramps 30 and 32 are removed from the upper surface of the side base sections 332 and 334 thereby enabling the side base sections 332 and 334 to be pivoted outward to the use position substantially in line with the central base section 330 as shown in FIG. 8 . The spray towers 220 and 222 may be unlatched and raised and locked in place in the use position shown in FIG. 8 . The ramps 30 and 32 are then reattached to the ends of the wash station as shown in FIG. 8 .
[0095] Another optional feature of any of the wash stations described above is shown in FIG. 10 and constitutes an overhead rail or support apparatus 380 which carries fluid discharge nozzles 382 in vertical and horizontally spaced positions for discharging cleaning fluid onto the top portion of a vehicle disposed on or moving across the wash station.
[0096] The overhead rail apparatus 380 may include a pair of vertically extending side rails 384 and 386 which are interconnected at one end by one or more horizontally extending cross rails 388 . Individual stationary and/or oscillating spray nozzles 382 are mounted in each of the vertically extending side rails 384 and 386 and the horizontal cross rail 388 as shown in FIG. 10 .
[0097] The side rails 384 and 386 and the cross rail 388 may be hollow to carry a fluid conduit or manifold through the entire overhead rail assembly 380 to provide fluid to the individual nozzles 382 . Alternately, the side rails 384 and 386 and the overhead cross rail 388 may support an exteriorly mounted fluid conduit.
[0098] It will also be understood that the side rails 384 and 386 and the cross rail 388 may be integrally formed as a one piece assembly or of separate components removably or fixedly interconnected by means of fasteners, interconnecting end profiles, etc. The lower end of the side rails 384 and 386 may be mounted on the wash station by separate mounting means, including a lower support fixed to the wash station in which receives the lower end of one of the side rails 384 and 386 or mounting collar on the lower end of the side rails 384 and 386 which can be releasably attached to the wash station.
[0099] Regardless of the mounting means used to mount the overhead rail assembly 380 to the wash station, the mounting means may provide separability of the overhead rail assembly 380 from the wash station to allow for convenient storage or transport of the wash station to and from the use site.
[0100] As shown in FIG. 10 , the lower ends of the side rails 384 and 386 may be mounted in a fixed or removable manner to the upper ends of the spray towers 220 and 222 by means of slide in, latching or telescoping fittings. The fluid flow conduits or passages extending from the source of cleaning fluid within the wash station base to the spray towers 220 and 222 are sealingly interconnected with the fluid carrying conduit or passage in the side rails 384 and 386 and the cross rail 388 to provide fluid flow from the source of cleaning fluid within the wash station base to the discharge nozzles 382 in the overhead rail assembly 380 . This sealing connection may be implemented by slide in fittings to enable the over head rail apparatus 380 to be easily mounted on and removed from the spray towers 220 and 222 .
[0101] Although the wash station of the present invention is discussed for use with a trailered apparatus being pulled by a tow vehicle, the wash station is usable by any vehicle, motorized or unmotorized vehicles, including, but not limited by, motorcycles, tractors, bicycles, trailers, agricultural equipment, movable construction equipment, land management, environmental and nautical equipment as well as trucks, and automobiles.
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A wash station for a vehicle is provided which includes a wash housing having a base with a platform as an upper surface. The platform has a plurality of spray nozzles laterally mounted across the platform. A tower having at least one spray nozzle therein is positioned on each lateral side of the platform. The towers are pivotable for pivoting into recesses in the base during transport. A drive-up approaching ramp is connected to the platform for directing the vehicle to the wash housing. The base houses a fresh water reservoir communicating with the spray nozzles. A control unit which may be housed in one of the towers activates the water delivery to the spray nozzles. The platform is configured with angled plates to direct waste water to a flush port or drain and into a waste reservoir in the base. The waste water can be either dispersed or filtered for recirculation. The base includes a pair of side sections and a central section. The pair of side sections are hingedly connected to the central section. The side sections are pivotable about the hinges for disposition on the central section for storage or transport.
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This application is a division of application Ser. No. 08/970,196 filed Nov. 14, 1997 now U.S. Pat. No. 6,024,147.
This application is based in part upon Disclosure Document No. 373320 dated Mar. 8, 1995 and Provisional Patent Application Serial No. 60/030,914, filed on Nov. 14, 1996.
FIELD OF THE INVENTION
The present invention relates to a new and useful method and industrial robotic device for applying coatings or other spray coated layers, in uniform thicknesses and at appropriate angles of pitch, in field applications, such as roofing applications or pavement applications.
BACKGROUND OF THE INVENTION
In the roofing applications, flat roofs are often made of polyurethane foam layers, which may be covered by various coatings, such as elastomeric coatings, such as silicone. It is difficult to maintain a uniform thickness when applying a foam or elastomeric material, which by its nature rises when applied to achieve a thickness above a roof base.
Furthermore, the faster that a foam applicator passes over a surface, the less volume of foam is applied, resulting in less of a thickness of the applied foam. To achieve thicker foam layers, a spray applicator is slowed down in velocity as it passes over the roof bases, so that more foam material is discharged per square unit of space of roof base being passed over by the spray applicator.
Various attempts have been made to apply foam uniformly, such as from an applicator moving at a uniform speed along a carriage track. However, at the end of each pass of an applicator over a portion of a roof base, the discharged foam is applied twice, i.e. once at the end of the pass to the edge, and again as it starts over above the previously applied foam, until the carriage can adjust to an unsprayed area.
Among prior art devices include U.S. Pat. No. 5,381,597 of Petrove which describes a wheeled robotic device for installing shingles on roofs. While it does not concern spraying of urethane foam upon a flat roof, it does describe a movable, wheeled carriage for use upon a roof.
U.S. Pat. No. 5,248,341 of Berry concerns the use of curved walls to accommodate spray paint applicators for curved surfaces, such as aircraft.
U.S. Pat. No. 5,141,363 of Stephens describes a mobile train which rides on parallel tracks for spraying the inside of a tunnel.
U.S. Pat. No. 5,098,024 of MacIntyre discloses a spray and effector which uses pivoting members to move an armature which holds a spray apparatus.
U.S. Pat. No. 4,983,426 of Jordan discloses a method for the application of an aqueous coating upon a flat roof by applying a tiecoat to a mastic coat.
U.S. Pat. No. 4,838,492 of Berry discloses a spray gun reciprocating device, wherein parallel tracks are used wherein each track is square in cross section, but further wherein each track guides a plurality of rollers thereon.
U.S. Pat. No. 4,630,567 of Bambousek discloses a spray system for automobile bodies, including a paint booth, a paint robot apparatus movable therein, and a rail mechanism for supporting the apparatus thereat.
U.S. Pat. No. 4,567,230 of Mayer describes a chemical composition for the application of a foam upon a flat roof.
U.S. Pat. No. 4,167,151 of Muraoka discloses a spray applicator wherein a discharge nozzle is moved transversally upon a frame placed adjacent and parallel to the surface having the foam being applied thereto. However, the applicator of Muraoka '151 does not solve the problem of excess foam being applied at the end of each transverse pass of the discharge nozzle.
U.S. Pat. No. 4,209,557 of Edwards describes a movable carriage for a nozzle applying adhesive to the back of a movably advancing sheet of carpeting. Similarly, Australian Patent no. 294,996 of Keith describes a movable carriage for a nozzle applying a polyurethane foam coating to a movably advancing sheet.
U.S. Pat. No. 4,016,323 of Volovsek also discloses the application of foam to a flat roof.
U.S. Pat. No. 3,786,965 and Canadian Patent no. 981,082, both of James et al, describe a self-contained trailer for environmentally containing a dispenser for uniformly dispensing urethane foam upon a terrestrial surface, wherein the problem of "skewing" occurs at the completion of each pass at the boundary edges of the surface to which are urethane foam is being applied. James '965 employs self-enclosed gantry robots to move the fluid discharge nozzle over the terrestrial surface.
U.S. Pat. No. 3,667,687 of Rivking discloses a foam applicator device.
U.S. Pat. No. 4,474,135 of Bellafiore discloses an apparatus for spraying a coating upon a spherical object supported by a post, which apparatus includes a curved track for providing orbital movement of a spray applicator about the exterior spherical surface or the sphere to be coated. While they are curved in nature, the curved tracks thereof are provided for orbital movement about the sphere, not to change the speed, tilt and direction of a linearly moving nozzle.
Another attempt to solve the problem of "double spraying" at a pass edge has been described in U.S. Pat. No. 4,333,973 of Bellafiore, which describes a similar spray applicator, such as that of Autofoam® Company. This spray applicator includes a wheeled, self-movable vehicle having a carriage portion with a horizontal linear track thereon. The spray applicator moves from one end of the track to the other, opposite end of the track at the end of one pass, of the applicator, above a portion of a roof base, and then the applicator reverses direction upon the track.
However, to avoid the "double spraying" problem noted above, the Autofoam® device has an on-off switch which turns the applicator off at an appropriate time at the end of a pass while the applicator is reversing direction, and re-starts the applicator a short time later when the applicator has started to move in the opposite direction.
Moreover, there are severe problems with this approach, as the constant "on-off" starting and re-starting of the applicator causes fatigue to the metal or other material parts of the applicator, and a detrimental effect to the end product. In addition, the Bellafiore '973 and Autofoam® devices are bulky and complicated to use.
OBJECTS OF THE INVENTION
Therefore, the objects of the present invention are as follows:
It is therefore an object of the present invention to provide a spray applicator for foam roofing which applies a coating of elastomeric foam of uniform thickness.
It is also an object of the present invention to provide a single yet efficient spray applicator for foam roofing.
It is also an object of the present invention to provide a spray applicator that can be disassembled into a few major parts for easy transport and reassembly on a roof without resorting to the use of a crane.
It is yet another object of this invention to provide a method for covering a large area of a roof with foam roofing using a continuous spray.
It is also an object of the present invention to provide a spray applicator with a nutating nozzle mount to minimize variations in coating thickness.
It is a further object of the present invention to provide a hand-held remote control to enable the spray applicator vehicle to operate without an on-board operator.
It is an object of the present invention to provide a method for continuous adhesive spraying and application of elastomeric sheet roofing material of large strip areas of a roof.
It is a further object of the present invention to provide accessories for the spray applicator vehicle to permit its use for applying elastomeric sheet roofing material from a roll.
Yet another objective of this invention is to provide a method and apparatus to provide fabric reinforced foam roofing.
It is also an object of the present invention to improve over the disadvantages of the prior art.
SUMMARY OF THE INVENTION
In keeping with these objects and others which may become apparent, and to solve the problems inherent in the Bellafiore '973 and Autofoam® spraying devices, the present invention uses one or more track rails, such as a double linear track of round cross section, as shown in the drawings herein, wherein there is an arcuate uphill end portion of the track at each side, so that the spray applicator, which moves along the one or more linear tracks, will accelerate in speed and tilt the discharge nozzle outward as it rolls up the curved uphill portion, thereby reducing the amount of foam applied to the edge portion of the roof at the end of a pass of the applicator.
To obviate the complicated mechanisms of the Autofoam® device, the present invention uses simple mechanics to move the spray applicator. For example, a radially extending swinging arm is provided for the sideways movement of the applicator along the track. To eliminate arcuate movement of the pivoting arm, a telescoping mechanism is provided, so that the spray applicator moves linearly, instead of arcuately, as the swinging arm moves about a pivot fulcrum point.
To further insure uniform thickness, the present invention further comprises various speed controls, so that an appropriate thickness can be applied for each pass.
For example, a rheostat controls the speed of the movement of the spray applicator, and an LED readout tachometer has a display dial with appropriate readings for appropriate speeds for corresponding desired thicknesses. Since the rate of flow of foam-producing material emanating from the nozzle is fixed, the ground movement speed of the applicator determines the weight of the coating per unit area applied. This, in turn, determines the thickness.
When a slope is desired on a flat roof, such as toward a drainage line, the ground speed of the foam applicator can be reduced on each successive pass away and parallel to the drainage line. This will result in a stepwise slope approximating the desired contour.
It has been found that a nutating nozzle holder, which tilts the nozzle a small amount cyclically as it traverses the track, can be used to minimize the variations in foam thickness (in the form of rounded ridges) due to the hollow-cone pattern of the nozzle.
Accessories can be added to the spray applicator so that it can be adapted for spraying adhesive on a roof or for automatically laying an elastomeric sheet covering such as Sure-Seal™ Fleece Back 100 EPDM made by Carlisle SynTec Incorporated of Carlisle, Pa. over a polyurethane foam substrate. Accessories can also be added for imbedding reinforced fabric within the polyurethane foal substrate.
While the invention has been described for use in applying roofing materials on roofs, it is also usable for spray applications at ground level such as for pavement painting or sealing applications.
DESCRIPTION OF THE DRAWINGS
The present invention can best be described in conjunction with the accompanying drawings, in which:
FIG. 1 is a top plan view of a spray applicator vehicle of the present invention;
FIG. 2 is a side elevation of a spray applicator vehicle of the present invention;
FIG. 3 is a side cross section detail of a transverse rail and carriage;
FIG. 4 is an end elevation of a transverse rail and carriage;
FIG. 5 is a block diagram of a spray applicator electrical system;
FIG. 6 is an end cross section of a coated roof with a central drain ridge;
FIG. 7 is a block diagram of a spray applicator electrical system using a hand-held remote control;
FIG. 8 is a nozzle spray pattern and resultant foam cross section;
FIG. 8A is a side elevation view thereof in cross-section;
FIG. 9A is a side elevation of a nozzle holder and an actuator cable; and,
FIG. 9B is a top plan view of a cam and cam follower;
FIG. 10 is a side elevation of a spray applicator as adapted for laying elastomeric sheet roofing material; and,
FIG. 11 is a side elevation of a spray application vehicle as adapted for applying fabric or mesh reinforced foam coating.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIGS. 1-2, spray applicator 1 is used for applying polyurethane foam coatings or other spray coated layers, in uniform thicknesses in field applications, such as roofing applications or pavement applications.
As shown in FIGS. 1 and 2, spray applicator vehicle 1 includes frame 2, operator seat 5, steerable powered single wheel 50, two unpowered side wheels 4, swinging boom 18, transverse rail subassembly 23 and various associated parts of nozzle 62 attached to carriage plate 26. Motor 6 drives sprocket 52 of chain 8 through gear reduction box 7 to provide vehicle motion via wheel sprocket 51. The operator steers the vehicle 1 by steering wheel 9, which moves steering linkage bar 57, thereby rotating wheel flange 58. Boom 18 is continuously reciprocated from pivot point 20 on tower 55 by crank arm 16 which is cyclically moved by reduction gear box 13 powered by motor 12, via adjustable linkage arm 14. Linkage arm 14 is attached to output shaft 17 and is rotated at a constant speed as determined by settings in control box 11. Slot 15 permits adjustment of the lateral movement limits of telescoping end 19 of boom 18. Rails 24 and 25 constrain the movement of carriage plate 26 to a linear path transverse to frame 2.
Control box 11 also sets the ground speed of vehicle 1. Hose 35, which may consist of two or more separate hoses or individual lumens, carries liquid materials for spraying through nozzle 62 from a remote pressurized source. For polyurethane foam, two chemicals supplied from separate hoses 35 are mixed at the nozzle 62 just prior to discharge. The two liquids interact chemically causing an exothermic foaming and hardening reaction. Hose 35 is retained in boom bracket 37 and may also be attached in one or more places by hook and loop straps 36. In normal use, a second (non-riding) work person guides hose 35. Solenoid 38, actuated by a switch in control unit 11, operates the discharge valve at nozzle 62.
It can be appreciated that vehicle 1 rolling at a constant speed with boom 18 reciprocating continuously is able to spray a continuous strip of coating on a surface. If the discharge rate at the nozzle is held constant, the amount of product sprayed on a surface per unit of sprayed area can be set by selecting ground speed.
Since the boom changes direction at the distal ends of its swings, a method is employed to limit the amount discharged to prevent "double coating" at the edges.
As noted before, prior art systems, such as described in Bellafoire '973 and of Autofoam® Company, shut the nozzle off at these portions of the cycle. However this action causes several problems.
For example, the on/off cycling has detrimental effects on spray material consistency from a chemical reaction point of view. The on/off cycling also causes mechanical wear and induces metal fatigue on brackets that must react to cyclic pressure loading.
In contrast to the devices of Bellafoire '973 and of the Autofoam® Company, the present invention uses a geometric arrangement and constant liquid product flow to prevent pattern edge build-up.
For example, FIG. 3 shows a cross section of rails 24 and 25 in the middle of the transverse sweep. Carriage plate 26, driven by end bushing 27 on telescoping extension 19, is shown with brackets 65 and 66 attached. Brackets 65 secure top rollers 29 with concave "hourglass" contours. Similarly contoured bottom rollers 53 are secured by brackets 66. Thus rollers 29 and 53 capture rails 24 and 25 constraining plate 26 to roll along these rails. Plate 26 also supports nozzle holder assembly 34 (not shown in this figure).
FIG. 4 shows an end view of rail subassembly 23. Both rails 24 and 25 are curved at their distal ends in a constant radius. Nozzle assembly 34 is shown in a flat vertical spray location at "A" and at an oblique spray location at the extreme limit of travel on the curved portion at "B". Top rollers 29 and bottom rollers 53 are offset from each other to facilitate easy rolling without binding on the curved portions. If boom 18 is reciprocated at an essentially constant rate, the carriage assembly is accelerated at the ends of travel due to the greater distance traveled per unit time on the curved end contour as well as the change in direction. Furthermore, the angle of nozzle 62 is tilted outward at the end so that the coverage area "BB" is larger than that of "AA". These end factors combine to reduce the thickness of the sprayed layer so that the "double layering" at the edge of each applied band of foam can be controlled to result in an edge thickness essentially the same as that of the center portion of a pass. This can be adjusted empirically based on the particular batch, temperature and other field conditions. The adjustment is the end limit position of nozzle 62 relative to the track end curve as determined by the adjustment of crank arm 16 in slot 15 of linkage arm 14.
Spray vehicle 1 is designed to be easily disassembled into four subassemblies for easy transport to the roof of a building on an elevator or by using a winch. Prior art systems require a crane. Booms 18 and 19 can be lifted off as a unit by removing spring pin 22 from upright link 54, spring pin 21 from pivot shaft 20 and spring pin 28 from carriage plate 26 coupling.
A front subassembly including of track subassembly 23 with uprights 3 can be removed by removing two spring pins 30 from frame member 2.
Central frame 2 subassembly including wheels 4 can be separated from the driven wheel subassembly (including seat 5 and steering wheel 9 by removing large spring pin 60 from socket member 59 on the frame subassembly. Then back chassis 10 can be lifted free. Electrical connections tying the various subassemblies have connectors which must be disconnected. The four subassemblies can then be reassembled on the rooftop.
FIG. 5 shows a block diagram of the electrical system largely housed in control box 11. The spray applicator vehicle 1 is electrically operated by connection to standard AC mains (typically 115 VAC at 60 HZ) via plug 40 and extension cord 39. A portable engine operated generator can supply this power as an alternative. Although two separate modular AC/DC converters 76 and 83 are depicted, a single converter can supply current to all DC loads.
An AC power switch 75 controls power to the entire spray applicator vehicle 1. Converter 76 supplies DC to a unidirectional speed control 77 with digital speed indicator 78 and speed set control 79. For maximum consistency of application, speed control 77 is preferable a PID type of feedback servo control which maintains output speed of motor 12 (for swinging of boom 18) constant via feedback from encoder 80 mounted on motor 12.
Switch 81 controls power to a solenoid 82 which opens the discharge valve at nozzle 62. Converter 83 supplies DC power to a bi-directional PID speed control 84 with digital speed indicator 85 and speed set control 86. This control accurately and repeatedly maintains the ground speed in either direction of spray applicator vehicle 1 as set even under varying load conditions by virtue of feedback encoder 87 mounted on motor 6.
This operation is used during the spraying operation and determines the thickness of the resulting sprayed layer. Control switch 89 determines the direction of movement as forward or reverse.
A second manual bi-directional speed control 90 is used to quickly select the desired ground speed via alternate manual control 91 when it is desired to maneuver spray applicator vehicle 1 prior or after a spray application.
In this manner, the carefully selected "automatic" setting for spraying is not altered. Either automatic speed control 84 or manual speed control 90 is actively enabled at any one time via selector switch 88.
The repeatable application of a desired amount of coating per pass permits the type of roof foam surfacing depicted in FIG. 6. This is an exaggerated cross section of the end of a roof 61 surface with a central drain 96 ditch with grate cover 95. If the roof 61 had a flat pitch, it would be desirable to create a pitch toward the drainage ditch for more effective drainage. This can be approximated by a stepped foam layer as shown, starting from lowest strip "A" and rising in thickness to strip "E" of the thickest cross section farthest from central drain 96. These strips can be applied in a single pass or in multiple passes by spray applicator vehicle 1 where the ground speed for layer "A" is fastest and the speed is reduced for each successive layer "B", "C", "D" "E" and "F".
For safety reasons, federal OSHA occupational safety regulations stipulate that a powered vehicle cannot be ridden by a workperson within ten feet of the edge of a roof. Also, a workperson is required to guide hose 35 while the operator rides and guides spray applicator vehicle 1. For these reasons, it would be desirable to operate spray applicator vehicle remotely. In this manner, a single workperson controls spray applicator vehicle 1 and guide hose 35.
FIG. 7 shows such a remote control configuration. Control box 11 is replaced by a hand-held remote control box 100 with a face plate and several vehicle mounted functional units. Since the operator is no longer physically on spray applicator vehicle 1, electric steering ram 102 replaces the steering wheel. Electric steeling ram 102 is controlled by positional steering control 101, which sets the position of steered wheel 50 to match that of steering control wheel 106 on remote control box 100.
Communications between remote control box 100 and spray applicator vehicle 1 is via coiled cable 105, although a fail-safe radio communications channel can be used as well. To limit the number of individual conductors in cable 105, a multiplexor/demultiplexor module 103 and 104 is used at each end of cable 105 to facilitate the two way communications. The function of similarly numbered components is the same as that explained above in reference to FIG. 5.
Hollow-cone nozzle 62 sprays a pattern 110 that impinges on the ground as shown in FIG. 8. As this pattern is swept sideways in a single pass, it will lay material that is denser toward the top and bottom edges resulting in a cross section with ridges 111 and valley 112 in the "Y" direction from roof surface 61.
While multiple sweeps by boom 18 mitigate this effect somewhat, ridges in the final sprayed surface still persist. This problem is eliminated by nutating or cyclically rocking the nozzle mount 34 slightly at right angles to rails 24 and 25 several times during each sweep to even out the coverage of hollow-cone nozzle 62 over multiple sweeps.
FIG. 9 shows optional modifications to accomplish this. The detail of FIG. 9A shows modified bracket 120 with pivot 121 holding nozzle mount 34. Bracket 120 is fastened to carriage plate 26. A push-pull cable assembly including armored housing sleeve 123 with cable 122 within is used to actuate the cyclic motion illustrated by the phantom representation (shown in broken lines) of nozzle holder 34 at the extreme outward position. The detail of FIG. 9B shows the powering end of cable 122. Bracket 126, attached to the frame of vehicle spray applicator 1 in the vicinity of gear box 13, retains sleeve 123. Cam follower 130 is pivoted at pivot point 128 within adjustment slot 127 and is biased toward multiple lobe cam 131 by spring 129. The stroke of wire 122 (and therefore the amount of cyclic tilt of nozzle holder 34) is determined by the dimensions and geometry of cam follower 130 and the depth of lobes on multiple lobe cam 131.
The proper centering of the motion of holder 34 is adjusted by moving pivot 128 within slot 127. Multiple lobe cam 131 is attached to the output shaft of gear box 13 under arm 14. It can be appreciated that cable wire 122 is cycled by each cam lobe as multiple lobe cam 131 rotates.
By moving cam follower 130 out of contact with multiple lobe cam 131 and tightening it in a locked position, to defeat the pivoting, nozzle holder 34 can be locked in a vertical position to defeat the nutating feature.
Alternatively, a separate small gear motor and crank coupling (not shown) mounted right on bracket 120 can be used to actuate the nutating action without need of cable 122.
Spray applicator vehicle 1 is easily modified to adhesively bond sheet elastomeric roofing material. As shown in FIG. 10, side arms 141 are pivoted at pivot point 140 from side extensions (not shown) which are attached to frame 2. These arms 141 have telescoping extensions 142 which are locked with hand screws 143. A roll of elastomeric sheet 144 is pivoted at the end of arms 142 at pivot point 148, with sheet end 145 trailing roll 144 as vehicle spray applicator 1 moves in the direction of arrow 149. Also pivoted at pivot point 148 are side arms 146 which trail a weighted roller 147, which weighted roller 147 applies even pressure to sheet layer 145. Nozzle 62 sprays a layer of bonding adhesive which bonds sheet 145 to roof surface 61.
Alternately, roll 144 can be adjusted to apply a skin coating of rolled material over the solidified foam layer applied from nozzle 62 to a surface, such as a roof.
Adjustment of extensions 142 determine the distance X between the sheet contact and the sprayed roof surface a fixed distance from the center of the spray cone. Since the vehicle moves at a predetermined constant speed, distance X can be used to match the optimal delay from adhesive application to contact of the sheet roofing material.
A method for applying reinforced foam roofing involves the use of a reinforcing fabric or open fabric mesh. The fabric can be manufactured of a variety of fibers such as nylon, fiberglass, aramid, etc. The method involves spraying a foaming mixture and immediately imbedding the reinforcing fabric in the mixture before the foam rises so that the reinforcing fabric rises with the foam and is embedded in the foam layer.
FIG. 11 shows modifications of the spraying applicator vehicle 1 for accomplishing this task. Side arms 160 are rigidly attached to frame 2 and uprights 3; they flare out at the distal end to lie outside of the spray pattern on each side. Roll 164 of lightweight reinforcing fabric is pivotly attached at the end of arms 160. The free end of fabric 165 is fed under light roller 162, which contacts surface 61 just at the edge of the foam adhesive spray pattern. Spring plunger 161 supported by brace 163 forces roller 162 into contact with roof surface 61. Foam spray 168, prior to rising, is contacted with fabric 165, which rises with foam 166 to embed itself in the foam layer as shown by the broken line.
It is further noted that other modifications may be made to the present invention without departing from the scope as noted in the appended claims.
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A method and an industrial robotic device for uniformly applying coatings at appropriate thickness and pitch upon a surface moves a spray applicator foam dispenser between two parallel tracks. The uniform application of foam at each pass is assured, by accelerating the speed of the foam dispenser at the end of each pass, by providing respective curved uphill distal ends of the tracks, so that the spray applicator foam dispenser moves up the curved distal ends and returns quickly while changing speed tilt and direction at the end of each pass.
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BACKGROUND OF THE INVENTION
This invention relates to an image reading section in an image reading device which is employed as image reading means in facsimiles, image scanners, etc., and more particularly to a charge detecting method of detecting the charges which photo-electric conversion elements produce in correspondence to the density data of minute regions in an original image, and a charge detecting circuit for practicing the method.
An image reading device set in close contact with an original in order to read the image of the latter comprises: a photo-electric conversion element array made up of a plurality of photo-electric conversion elements arranged in a line; and a drive IC for driving the photo-electric conversion element array. The drive IC includes switches which are adapted to select the photo-electric conversion elements forming the photo-electric conversion element array one after another to apply the charges generated in the photo-electric conversion elements to one output line in a time-sequential manner.
The photo-electric conversion element array has a light receiving section made up of a plurality of photo-electric conversion elements. Each element is formed by arranging a metal electrode and a transparent conductive film on both sides of an amorphous silicon (a-Si) layer, so as to detect optical charges formed by light reflected from an original image.
A simple equivalent circuit for one bit of the image reading device is as shown in FIG. 7. The circuit operates as follows: When a light beam reflected from an original and including data on the density of a small region of the original image is applied to a photo-diode PD, an optical current Ip flows in the photo-diode PD to produce an optical charge therein. The charge thus formed is stored in a capacitor Cp formed by the light receiving element and a capacitor CL formed by wiring (hereinafter referred to as "a wiring capacitor CL", when applicable), so that the voltage Va of an input line of an amplifier A is increased. The amplifier A detects the voltage Va with high input impedance. The output of the amplifier A is applied by means of an analog switch SW to an output line T out for every bit, to form a time-series signal. Thereafter, the amplifier A is reset; more specifically, the input line of the amplifier A is grounded through a reset switch RS. Therefore, as the wiring capacitor CL decreases, the voltage Va of the input line of the amplifier A is increased, and accordingly the signal detection accuracy is increased.
The above-described image reading device is disadvantageous in that, since a number of photo-electric conversion elements 70 are driven individually, it is necessary to use a number of driving ICs with the result that the manufacturing cost is increased as much. In order to overcome this difficulty, a matrix drive type image reading device has been proposed in the art which is lower in manufacturing cost with the number of driving ICs decreased.
The matrix drive type image reading device, as shown in FIG. 8, comprises: K photo-electric conversion element groups each consisting of n photo-electric conversion elements 70; and switching elements T ll -T kn which are provided for the photo-electric conversion elements 70, respectively. The switching elements T ll -T kn are connected to n common signal lines 80. For every block, the switching elements T ll -T kn are turned on by gate pulses applied to gate lines Gl-Gk, so that several bits are connected to the common signal lines at the same time, thus being processed in a parallel mode.
For simplification in description, the operation of the image reading device will be described with reference only to the first block. It is assumed that, when the switching elements T ll -T ln are turned off, a light beam reflected from an original which includes data on a small region of the original image is applied to the image reading device. In this case, in response to the light beam, optical currents Ip flow, thus producing optical charges. The charges thus produced are stored in the light receiving element capacitors C Pll -C Pln and in the overlap capacitors C GD between the drains and gates of the switching elements. When the switching elements T ll -T ln are turned on, the aforementioned charges are distributed to the overlap capacitors C GS between the sources and gates of the switching elements, the wiring capacitors C Ll -C Ln , the light receiving element capacitors C Pll -C Pln , and the overlap capacitors C GD . Therefore, in order to sufficiently transfer the charge to the wiring capacitors C L , the capacitance must be much larger than the light receiving capacitance C P , and the overlap capacitances C GS and C GD . The changes in potential of the common signal lines 80 due to the charges stored in the wiring capacitors C Ll -C Ln are transmitted through amplifiers A l -A n to an output line T out by closing analog switches SW l -SW n in a driving IC 81 one after another, so that they are detected in a time-sequential manner. The above-described operation is carried out for every block, so that an image signal is formed for one line of the original.
In the image reading device described with reference to FIG. 7 which employs the potential detecting method, the signal detection accuracy is increased with the decreased capacitance of the wiring capacitor, as was described before; however, it is impossible to decrease the capacitance because of the following reason: In order to allow an optical current to flow in the photo-diode PD, the reverse bias voltage VB across the photo-diode PD must be sufficiently high. If the wiring capacitor CL is small in capacitance, then the reverse bias voltage VB is decreased as the voltage across the wiring capacitor CL increases. If the effective reverse bias voltage VB of the photo-diode PD decreases in this manner, then it becomes impossible to supply the optical current. However, it should be noted that the voltage across the wiring capacitor can be increased as the capacitance of the wiring capacitor decreases as long as the reverse bias voltage VB does not adversely affect the optical current.
In the image reading device of matrix drive type described with reference to FIG. 8, the charges are transferred through the switching elements T kn to the wiring capacitors C L and stored therein. Hence, in order to improve the charge transferring efficiency, it is necessary to make C L much larger than (C P +C GD ). For this purpose, it is necessary to reduce the voltage developed across the wiring capacitor C L to a small fraction of that provided on the side of the photo-electric conversion element 70. Hence, the voltage is amplified in the driving IC 81, thus increasing the sensitivity. In this operation, offset noises or random noises occur with the driving IC 81, thus lowering the S/N ratio.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to eliminate the above-described difficulties accompanying a conventional image reading device.
More specifically, an object of the invention is to provide a charge detecting method in which a voltage detecting capacitor is made variable in capacitance, to increase an effective detection voltage thereby to improve the signal detection accuracy, and a charge detecting circuit for practicing the method.
A charge detecting method according to the invention comprises the steps of setting a variable capacitor to a predetermined capacitance, injecting a charge into the variable capacitor, changing only the capacitance of the variable capacitor with the charge maintained in the variable capacitor, and detecting a voltage developed across the variable capacitor.
Further, a charge detecting circuit according to the invention comprises a variable capacitor whose capacitance is changed by external means, injecting means for injecting a charge into the variable capacitor, and detecting means for detecting a voltage developed across the variable capacitor.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is an equivalent circuit diagram, partly as a block diagram, showing an example of an image reading device which constitutes a first embodiment of the invention;
FIG. 2 is an explanatory diagram for a description of the structure of a variable capacitor shown in FIG. 1;
FIG. 3 is an equivalent circuit diagram showing one bit in the image reading device shown in FIG. 1;
FIG. 4 is a timing chart showing signals for the one bit in the image reading device shown in FIGS. 1 and 3;
FIG. 5 is an equivalent circuit diagram showing one bit in another example of the image reading device which constitutes a second embodiment of the invention;
FIG. 6 is a timing chart showing signals for the one bit in the image reading device shown in FIG. 5; and
FIGS. 7 and 8 are equivalent circuit diagrams showing examples of a conventional image reading device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of this invention will be described with reference to the accompanying drawings.
First, a matrix drive type image reading device which constitutes a first embodiment of the invention, will be described with reference to FIG. 1.
As shown in FIG. 1, a photo-electric conversion element array is made up of a plurality of photo-electric conversion elements 70 corresponding to bits, and the photo-electric conversion elements 70 are connected through switches Sll-Sln to variable capacitors CEXT. In FIG. 1, parts corresponding functionally to those which have been described with reference to FIG. 8 are accordingly designated by the same reference numerals or characters.
The switches Sll-Sln are made up of thin film transistors, and the variable capacitors CEXT are of a lamination structure. The switches and the variable capacitors are formed in the same manufacturing process as the photo-electric conversion elements 70 and the switching elements T kn .
Each of the variable capacitors CEXT is so designed as to change its capacitance into two values in response to external signals. The structure of each variable capacitor CEXT will be described with reference to FIG. 2. As shown in FIG. 2, the variable capacitor is formed by laying a metal electrode 21, an insulating layer 22, a semiconductor layer 23, and a metal electrode 24 one on another in the stated order. A pulse voltage is applied to the metal electrode 21. Examples of the material of the metal electrodes 21 and 24 are metals such as Au, Cr, Mo, Ti and Ta which are low in resistance and which are stable with temperature and chemicals so that they are not deteriorated during photolithographing in the formation of the capacitor; or Oxide conductors such as SnO 2 and ITO. The insulation layer 22 is made of an oxide or nitride such as SiN x , SiO x , TaO x and TaON x . The semiconductor layer 23 is made of p-type or n-type semiconductor which is formed by doping impurities into amorphous silicon, or amorphous silicon semiconductor including germanium or carbide.
When a voltage higher than that at the metal electrode 24 (for instance +5 V) is applied to the metal electrode 21, an electron storage layer is formed in the interface of the insulating layer 22 and the semiconductor layer 23, as a result of which, in the variable capacitor, the region from the metal electrode 24 up to the interface becomes low in resistance. Therefore, the capacitance between the metal electrodes 21 and 24 may be represented by C1 corresponding to the thickness of the insulating layer 22. When, on the other hand, a voltage lower than that at the metal electrode 24 (for instance -5 V) is applied to the metal electrode 21, the depletion of electron occurs on the semiconductor side of the interface of the insulating layer 22 and the semiconductor layer 23, thus providing high resistance. When the depletion has advanced sufficiently, the capacitance between the metal electrodes 21 and 24 becomes C2 corresponding to the serial connection of the insulating layer 22 and the semiconductor layer 23. The capacitance C2 is smaller than the capacitance C1. Therefore, the capacitance of the variable capacitor CEXT can be changed with the potential of the metal electrode 21.
Each of the switches Sll to Sln is so provided that, when each variable capacitor CEXT is decreased in capacitance, the charge transferred to the CEXT may not be redistributed to the overlap capacitors C GS formed between the gates and sources of the respective switching elements (T kn ). That is, it is used to electrically disconnect the variable capacitor CEXT from the switching elements (T kn ), thereby to allow the variable capacitor to change in capacitance with the charge maintained therein.
FIG. 3 shows the arrangement of a detecting circuit with the variable capacitor CEXT in detail.
The detecting circuit comprises: the variable capacitor CEXT; a voltage circuit 31 connected to the metal electrode 21 of the variable capacitor CEXT, to control the potential of the metal electrode 21; a reset switch RS connected between the metal electrodes 21 and 24, to reset the variable capacitor CEXT; i.e., to discharge the latter; an equimagnification amplifier DA1 one input terminal of which is connected to the metal electrode 24 of the variable capacitor CEXT; a differential amplifier DA2 for amplifying the potential difference between the output terminal of the amplifier DA1 and the metal electrode 21 of the variable capacitor CEXT; and the above-described switch S1. The charge stored in the variable capacitor CEXT changes the voltage across it in accordance with the capacitance of the capacitor CEXT. In order to eliminate the change in potential of the metal electrode 21, the voltage across the capacitor CEXT is detected through the differential amplifier DA2.
The operation of the detecting circuit shown in FIGS. 1 and 3 will be described with reference to FIG. 4, which is a timing chart corresponding to one bit for a photo-electric conversion element.
In response to a gate pulse (Gk) and a switching pulse (PSln) for the switch (Sln), the switching element (T kn ) and the switch (Sln) are turned on so that the photo-electric conversion element 70 is connected to the variable capacitor CEXT. The switching pulse (PSln) is made larger in pulse width than the gate pulse (Gk) so that the switch (Sln) is closed when the switching element (T kn ) is closed.
When the switching element (T kn ) is turned on by the gate pulse (Gk), the charge is transferred into the variable capacitor CEXT the capacitance of which has been increased to C1.
Thereafter, the switch (Sln) is opened so that the photo-electric conversion element 70 is electrically disconnected from the variable capacitor CEXT. Under this condition, a capacitance changing pulse is applied to the metal electrode 21 of the variable capacitor CEXT to change the capacitance of the latter into C2 (C2<C1). The variable capacitor CEXT has been electrically disconnected from the switching element (T kn ) as was described above. Therefore, the charge will not be distributed to the overlap capacitor C GS of the switching element (T kn ), and accordingly, the variable capacitor CEXT can be changed in capacitance and in voltage with the charge maintained unchanged. The changed voltage (V CEXT ) across the variable capacitor CEXT is detected by the differential amplifier DA2. Therefore, the variable capacitor CEXT are discharged by the input reset signal (Rs).
FIG. 5 is an equivalent circuit showing one bit in a matrix drive type image reading device, which constitutes a second embodiment of the invention. In FIG. 5, parts corresponding functionally to those which have been described with reference to FIG. 8 are therefore designated by the same reference numerals or characters.
In the image reading device, for each bit including a photo-electric conversion element 70, a variable capacitor CEXT is provided which is made up of a number (n) of capacitors CL l -CL n . The terminals of the capacitors CL l -CL n are connected through a plurality of switches S2 l -S2 n as shown in FIG. 5 so that the capacitors can be connected in parallel to one another through the switches. Furthermore, the terminals of the capacitors CL l -CL n are connected through a plurality of switches S3 l -S3 n as shown in FIG. 5, so that the capacitors are connected in series to one another. That is, the capacitors CL l -CL n are connected in parallel to one another by closing the switches S2 l -S2 n , and are connected in series to one another by closing the switches S3 l -S3 n . More specifically, the capacitance of the variable capacitor CEXT comprising the capacitors CL l -CL n can be changed into two values by operating those switches. A switching element T provided for the photo-electric conversion element 70 is connected to the end capacitor CL l , so that, when the parallel connection is switched over to the series connection, the potential at the terminal P is prevented from being changed; that is, the transfer of charge to the switching element is prevented.
The variable capacitors CEXT are contained in the IC chip; however, the invention is not limited thereto or thereby.
The operation of the detecting circuit shown in FIG. 5 will be described with reference to FIG. 6, which is a timing chart corresponding to one bit for the photo-electric conversion element 70.
In response to an S2 control pulse, the switches S2 l -S2 n are closed so that the capacitors CL l -CL n forming the variable capacitor CEXT are connected in parallel to one another. Assuming that all the capacitors have a capacitance C, the resultant capacitance of the capacitor CEXT is (n×C).
When the switching element T is closed in response to a gate pulse, the charge is transferred from the photo-electric conversion element 70 to the variable capacitor CEXT whose capacitance is (n×C), to saturate the capacitor.
When the switches S3 l -S3 n are closed by an S3 control pulse, the capacitors CL l -CL n forming the variable capacitor CEXT are connected in series to one another, so that the capacitance of the variable capacitor CEXT is set to (C/n). In this case, the charges are redistributed in the capacitors CL l -CL n ; however, since the switching element T is connected to the end capacitor CL l , the voltage across the capacitor CL is maintained unchanged, and accordingly the charge is not returned to the switching element T. Hence, in the second embodiment, unlike the first embodiment shown in FIG. 1, it is unnecessary to provide the switches (Sll-Sln in FIG. 1) for electrically disconnecting the switching elements T from the variable capacitors CEXT.
That is, in the second embodiment, the capacitance of the variable capacitor CEXT can be changed with the charge maintained therein. When the capacitance of the variable capacitor CEXT is changed in this manner, the voltage applied to the amplifier A is changed, and the voltage thus changed is detected as a detection signal.
The residual charge in the variable capacitor CEXT is removed by application of the input reset signal.
In the second embodiment, the switches S2 l -S2 n and S3 1 -S3 n and the variable capacitors CEXT including a number of capacitors CL l -CL n are formed in an IC chip, which is used to form the image reading device. Therefore, the image reading device is simple in the film manufacturing process, and is high in manufacture yield.
As apparent from the foregoing description, according to the invention, a variable capacitor is charged with the capacitance set to a large value, and the voltage developed across the variable capacitor is detected with the capacitance set to a small value. Hence, when the signal detection is not carried out, the capacitance of the variable capacitor is increased, so that the variable capacitor functions as a low impedance element which causes no voltage change; and when the signal detection is carried out, the capacitance is decreased, so that the voltage to be detected is increased; that is, the S/N ratio is increased, thus improving the sensitivity.
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A method of detecting the charges which photo-electric conversion elements produce in correspondence to the density data of minute regions in an original image. In the method, a variable capacitor is charged with the capacitance set to a large value, and the voltage developed across the variable capacitor is detected with the capacitance set to a small value, whereby the voltage to be detected is increased as much, with an improvement in the signal detection accuracy.
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FIELD OF THE INVENTION
[0001] This invention relates to apparatus for and a method of obtaining thermal property data on thermal properties of a temperature controlled system, to a controller for a temperature management system and to a temperature management system having such a controller.
BACKGROUND TO THE INVENTION
[0002] The invention is particularly, but not exclusively, applicable to the control of a heating and/or cooling system, such as a central heating system or air conditioning system for the home or office. It is still the case that most domestic space heating systems control temperature by targeting a set point temperature (which may form part of a schedule of such temperatures that vary over a control period) and using a thermostat with hysteresis to turn the heat source on and off. This type of control is based only on the current state of the house and its heating system, and does not take into account any forward planning or knowledge of the thermal response of the house.
[0003] Consequently, the known method can fail to achieve energy efficiency and/or the best comfort for the occupants of the house, and provides the occupants practically no insight into the thermal performance of the house and the heating/cooling system, for example the rate of heat loss from the house to the external environment and the energy input to the heating/cooling system that will be required in order to achieve a desired temperature change within the house. These drawbacks are particularly pertinent to the control of a heat pump-based heating or cooling system.
[0004] There are existing systems which remotely measure room temperature and enable the home owner to view the recorded temperature traces by an internet page, but the services rarely provide any additional insight. Some existing services to provide some analysis (see for example https://www.myjoulo.com/) but not to the extent of taking into account the thermal properties of the house.
[0005] It has been proposed to control temperature within a building using a system in which the effect of an energy input into the building's heating or air conditioning system on temperature is predicted using data on the thermal characteristics of the building and on external conditions. In the paper “Optimization of a Heating System using Smart Meters and Dynamic Pricing” (Huval. XP002696078) it is proposed to determine a schedule for the heat to be supplied by a heating system by determining a control schedule of a hot water supply valve (that controls the supply of hot water to a heater) in order to minimise a cost function comprising the sum of the cost of heating the building and the cost of “loss of comfort”. However, the document does not discuss how the building thermal parameters, necessary for the predictive model, are determined and indeed indicates that it would be problematic for an individual household to find the necessary coefficients in order to set up an accurate model.
[0006] Certain control systems incorporate “optimum start” facilities, whereby the rate of increase of temperature with time is learned when the house is being heated up, and this gradient value is then used to subsequently calculate when to start heating in order for the house to get to a particular temperature at a particular time, and can thus perform a more accurate optimum start time calculation. Other systems learn simple characteristics in order to reduce heating system “undershoot” and “overshoot”, as a result of the hysteresis mentioned above (e.g. U.S. 2010/0096467). However, the systems cannot predict the thermal response of a house particularly accurately, especially where the temperatures of the house do not change significantly over time, for example the house heated by an underfloor heating system or a heat pump.
SUMMARY OF THE INVENTION
[0007] According to a first aspect of the invention, there is provided a method of obtaining thermal property data on thermal properties of a temperature controlled system which includes temperature control apparatus, said data being suitable for use in predicting the temperature of at least part of the system, the method comprising the steps of:
(a) monitoring the temperature of at least part of the system over a succession of portions of a data acquisition period and recording said temperature for each portion in an electronic memory; (b) determining heat supply/removal data for the period, said heat supply/removal data being indicative of the amount of heat energy supplied to, or removed from said part by the temperature control apparatus over the period; and (c) determining the thermal property data from the recorded temperatures and heat transfer data, wherein the thermal property data are determined by a process of statistical inference.
[0011] Preferably, said process of statistical inference comprises the steps of:
(d) sampling a set of possible thermal property data; (e) determining a likelihood value, indicative of the probability of the selected data being consistent with recorded temperatures; and (f) repeating steps (d) and (e) for other, iteratively selected samples of possible thermal property data.
[0015] Conveniently, said steps (d) and (e) are repeated a predetermined number of times, the final sample constituting said thermal property data.
[0016] The statistical inference process enables the thermal property data to be sufficiently accurate for the associated thermal parameters of the temperature controlled system to be determined, if desired. This information can provide a useful insight into the thermal performance of the system, for example predicted heating and cooling rates of the system in various circumstances, the energy required by the temperature control apparatus to ensure the system conforms to a required temperature or schedule of set point temperatures or the amount of heat energy transferred between the temperature control system and the external environment. The acquisition of thermal property data does not necessarily require any alteration of the operation of the temperature control apparatus, nor a change of temperature of the temperature controlled system.
[0017] The thermal property data can be used in the control of the temperature control apparatus, by being fed into a thermal model for the temperature controlled system, from which the energy requirements needed for the temperature control apparatus to achieve a desired temperature of the temperature controlled system can be anticipated and this data can be used in determining an operating schedule for the temperature control apparatus.
[0018] The temperature controlled system may be any system that needs to have its temperature controlled over an extended period, for example, a domestic or commercial oven or laboratory incubator.
[0019] Preferably, however, the temperature controlled system comprises at least one room, for example in a domestic dwelling or an office of an office block, the temperature control apparatus comprising a heating and/or cooling system for the room.
[0020] In this case, the invention provides data that can be used to assess the thermal properties of a room or house (for example the efficacy of any insulation for the room or house) and/or can be used in optimising the performance of a heating/cooling system for the room, for example by the method described in the Huval paper mentioned above or the method described and claimed in the present applicant's PCT Patent Application No. PCT/GB2013/050376.
[0021] Preferably, the thermal properties, in respect of which said thermal property data are obtained, comprise any two or more thermal parameters, such as the heat capacities and thermal transfer properties of the room or of the heating and/or cooling system, the thermal transfer properties as between the room and the environment external to the room, or an arithmetic combination or function of said capacities and thermal transfer properties.
[0022] Preferably, said thermal properties further comprise the heat capacity and thermal transfer properties of the thermal mass of the room or a function of said properties, or arithmetic combination of the properties with one or more of the other thermal properties.
[0023] Preferably, the thermal capacity of the heating and/or cooling system is combined with heat energy supplied to or removed from the room and this combined quantity is part of the thermal property data determined by said process of statistical inference.
[0024] The process of statistical inference is preferably a process of Bayesian Inference.
[0025] Additionally or alternatively, the process may be a forward filtering backward sampling process.
[0026] Step (b) above, of determining the heat supply/removal data, may comprise monitoring control signals to the temperature control apparatus and calculating or estimating the heat supply/removal data from the data obtained by said monitoring.
[0027] Where the temperature control apparatus transfers heat with the room by means of a circulating heat transfer medium (for example water being pumped through radiators), the determining of the heat supply/removal data may additionally comprise determining the temperature(s) of the transfer medium at the output of the temperature control apparatus, by a process of statistical inference.
[0028] The invention is also applicable where the control signals to the temperature control apparatus are not known, in this case the determination of the heat supply/removal data being achieved by means of a statistical inference process, preferably a particle filter technique applied to the recorded temperatures.
[0029] The invention also lies in assessment apparatus for performing the aforesaid method.
[0030] More particularly, according to a second aspect of the invention, there is provided assessment apparatus for obtaining thermal property data on thermal properties of a temperature controlled system which includes temperature control apparatus, said data being suitable for use in predicting the temperature of at least part of the system, the assessment apparatus comprising at least one temperature sensor for monitoring the temperature of at least part of the system over a succession of portions of a data acquisition period, an electronic memory for storing said temperatures for each portion, a data processor arrangement operable to estimate heat supply/removal data for the period, said heat supply/removal data being indicative of the amount of heat energy supplied to or removed from said part by the temperature control apparatus during each portion, and to determine the thermal property data from the recorded temperatures and heat supply/removal data, wherein the data processor arrangement is operable to determine the thermal property data by a process of statistical inference.
[0031] According to a third aspect of the invention, there is provided a controller for a temperature management system for heating and/or cooling a room, comprising an output for control signals to the temperature management system and said assessment apparatus, wherein the electronic memory is arranged also to store said thermal property data and said data processor arrangement is also operable to calculate, for each portion of a control period, the heat energy to be transferred by the heating and/or cooling system for the temperature in the room to meet a given one or more conditions over the control period.
[0032] For example, the condition could be that the temperature conforms to a set point schedule over that period. Alternatively, the condition could be that the sum of the cost of supplying energy to the heating/cooling system and a parameter representative of a predetermined acceptability of variations from a set point temperature is minimised.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The invention will now be described, by way of example only, with reference to the accompanying drawings in which—
[0034] FIG. 1 is a functional block diagram illustrating the interaction between a controller in accordance with the invention and a house fitted with a heating system comprising a boiler which supplies hot water to radiators distributed throughout the house; the controller also incorporating assessment apparatus in accordance with the invention for conducting a method in accordance with the invention;
[0035] FIG. 2 is a block diagram representation of a thermal model used, in effect, by the controller to predict future temperatures of the interior of the house in response to different energy inputs to the boiler, the model including the thermal property data to be obtained by the method in accordance with the invention;
[0036] FIG. 3 is a block diagram illustrating an iterative process for determining the thermal property data (represented as the vector r);
[0037] FIG. 4 is a block diagram illustrating how the thermal property data obtained by “thermal parameter learning” can be used to assist in the automated control of the heating system and, optionally, to provide the user/home owner with insight to the thermal behaviour of the house (and/or recommendations for changes in the way the heating system for the house is controlled); and
[0038] FIGS. 5 to 10 are graphs illustrating a data generated worked example of the method in accordance with the invention.
DETAILED DESCRIPTION
[0039] In FIG. 1 house 1 has one or more rooms (not shown) which are heated by a heating system comprising a boiler 2 linked to a heat delivery system (not shown) which in this example takes the form of a set of radiators through which water heated by the boiler 2 is circulated. It will be appreciated that other types of temperature management systems could be used, for example heat pump based heating and/or cooling systems or storage heaters.
[0040] A temperature sensor (or a respective sensor in each room) is denoted by the reference numeral 4 , and monitors the temperature of the room in question. The output of the sensor is fed to an input 6 of a controller generally referenced 8 . In FIG. 1 , the controller 8 is represented as three functional blocks, a control block 10 for actually controlling the boiler 2 , a thermal parameter learning block 12 for determining the thermal property data for the house 1 and a user suggestion engine for providing a home owner/user with information that provides an insight into the thermal performance of the house 1 . The information from the block 14 is displayed to the user via a user interface 16 which may, for example, take the form of a computer terminal and/or touch screen. The interface 16 also enables the user to send command and settings information to a control input 18 of the controller 8 .
[0041] An output 20 on the controller 8 provides control signals for the boiler 2 , and these are fed to the input P of the thermal parameter learning block 12 . Both the block 12 and the block 10 receive external temperature data from a suitable source 22 , such as an external sensor or internet weather station. This data is indicated by the symbol T E in the block 12 , whilst the input for the control block is denoted by the reference numeral 24 . It can be seen that the learning block 12 also receives the data from the sensor(s) 4 at input y. It will be appreciated that other external data may be taken into account.
[0042] The thermal parameter learning block 12 uses a process of Bayesian Inference on the data fed to the block (T E , y, P) to infer vectors X, E and r respectively representative of the hidden temperature state, energy input (from the boiler) and thermal parameters of the house 1 .
[0043] The structure of the vectors X and r are described below.
[0044] As can be seen, the data in the vectors X, E can be processed by the suggestion engine 14 to provide the insight mentioned above, whilst the thermal parameters, arranged in the vector r are used for similar purposes by the engine 14 , and are also used by the controller 10 to predict the quantitative effect of the operation of the boiler 2 , in response to control signals, on the temperature(s) within house 1 .
Modelling Approach
[0045] The described method infers detailed thermal characteristics of a house, such as time constants for heating and cooling, from measured temperature traces and optionally control signals. Our approach involves representing the house with a simple physics model, and then using Bayesian inference to deduce “backwards” the model parameters that have the best match to the measured data. The model can subsequently be used in the “forward” direction to predict temperature response, energy consumption etc. This predictive ability has a number of advantages (see description of example Applications in later sections).
[0046] We model the house as three or four thermal blocks, corresponding to the fabric of the house as well as elements of its heating system (such as radiators). The state of the house is a vector of temperatures x(t) at time t, with one vector component for each thermal block.
[0047] FIG. 2 is a simple physics model, with three blocks that can hold heat and transfer heat between each other. These are
(a) the heating system 26 (radiators, underfloor, etc.)—which is directly heated by the heat plant; (b) the room 28 —which is heated by the heating system, and loses heat to the outside world; and (c) the remaining “disconnected” thermal mass 30 of the house—which can exchange heat with the room (only).
[0051] Each of these has a heat capacity C (i.e. quantity of thermal material, taking a certain amount of energy to raise its temperature T), and each link has a thermal conductance k.
[0052] The energy flow between the blocks is represented by arrows.
[0053] The physics can be written as three coupled linear differential equations for the conduction of heat between each block and the resulting change in temperature:
[0000]
C
R
T
R
t
=
k
H
(
T
H
-
T
R
)
-
k
W
(
T
R
-
T
E
)
+
k
M
(
T
M
-
T
R
)
C
H
T
H
t
=
E
-
k
H
(
T
H
-
T
R
)
C
M
T
M
t
=
-
k
M
(
T
M
-
T
R
)
[0054] There is an approximation here. Radiators (and also underfloor heating) transfer heat to the room by convection and radiation as well as conduction, which means there is a non-linear relationship between temperature difference and heat transfer. Nevertheless, we can regard the above equations as a linearised approximation around a “baseline” temperature difference, and iterative corrections can if necessary be made for the non-linearity.
[0055] A matrix formulation means that the above equations can be more simply represented, and also provides an elegant framework for manipulating sets of temperatures—particularly when we need to manipulate time series of sets of temperatures. This approach is known as a “state space” formulation and is a more modern replacement for the more traditional “transfer function” approach to control theory.
[0056] The differential equations above can be rewritten in matrix form as:
[0000]
x
(
t
)
t
=
A
d
(
t
)
×
(
t
)
+
B
d
(
t
)
E
(
t
)
+
F
d
(
t
)
T
E
(
t
)
(
1
)
[0000] where T is a vector of temperatures
[0000]
T
=
(
T
R
T
H
T
M
)
[0000] and the other symbols are matrices or vectors of the thermal parameters of the house {C, T, k}. The suffix d indicates that these matrices and vectors are differential.
[0000]
A
_
_
d
=
(
-
k
H
-
k
W
-
k
M
C
R
k
H
C
R
k
M
C
R
k
H
C
H
-
k
H
C
H
0
k
M
C
M
0
-
k
M
C
M
)
;
B
_
d
=
(
0
1
C
H
0
)
1
E
max
;
F
_
d
=
(
k
W
C
R
0
0
)
[0057] The zeros arise from the assumption that there is no direct heat transfer between the heating system and the thermal mass of the house. In this case there are 6 independent parameters that describe our house model (whether or not the true boiler power is known).
[0058] The dynamics of the house are modelled by the evolution matrix A d , and E(t) is a vector of energy inputs to the house (such as the power output from a boiler, usually scaled to ensure 0<E<1 always—see further discussion in “Energy inference” below), whose effect on the house is represented by the matrix B d , and T E is a vector of external influences to the house (such as the external temperature), whose effect on the house is represented by the matrix F d .
[0059] Our thermal parameter learning process will in effect infer values for the matrices A d , B d and F d .
[0060] In the example model, the state of the house is represented by three temperatures (the room temperature, the temperature of the water in the heating system, and the temperature of the internal thermal mass of the house, respectively), where there is a single energy input to the house, and where there is a single external influence (the outside temperature. In this case the model matrices can be expressed as
[0000]
A
d
=
(
-
r
1
-
r
2
-
r
3
r
1
r
3
r
4
-
r
4
0
r
5
0
-
r
5
)
;
B
d
=
(
0
r
6
0
)
1
E
ma
x
;
F
d
=
(
r
2
0
0
)
(2)
[0000] and they have no time-dependence. x(t) is a three-dimensional vector and E(t) and T E (t) are scalar quantities. In this case, the vector r=(r 1 r 2 r 3 r 4 r 5 r 6 ) is the set of thermal parameters that we are trying to learn—six numbers that characterise the thermal dynamics of the house. In general, the constitution and size of all of the matrices may be different.
[0061] The output of our thermal parameter learning process will be the vector r (from which the matrices A d , B d and F d can be reconstructed).
[0062] The vector r consists of (inverse) time-scales for the house and heating system, with the units of each element thus being 1/time. The r-parameter for energy input r 6 will be different from this—it is often a temperature gradient rather than an inverse time-scale (see discussion below on Energy Inference). E max is the maximum heat energy that can be output by the boiler. In this case the boiler burner is not modulated, so the boiler is either fully on or off.
Hidden Markov Terminology
[0063] We will also use a simplified formulation of the house model within this disclosure, equivalent to a standard hidden Markov model:
[0000] x k =A k x k−1 +B k +n x ,
[0000] This is simply a linearised version of Eqn (1) with a discrete timestep Δt, at the discrete time index k. With a straightforward linear approximation as long as Δt is small:
[0000]
A
k
=I+ΔtA
d
, B
k
=ΔtB
d
E
k
+ΔtF
d
T
E,k
[0000] where I is the identity matrix. The matrix A k describes the thermal model of the house, and will usually not be time varying; the vector B k contains external influences on the hidden state. The vector E K describes one or more of the energy outputs from the heating system.
[0064] Note that since the overall aim is to infer the vectors of parameters r underlying the thermal model of the house, it would be clearer to write Eqn 3 with the r-dependence made explicit:
[0000] x k =A k ( r ) x k−1 +B k ( r )+ n x
[0065] It should be borne in mind in all future equations that A k and B k are functions of r, and that B k is also a function of energy input E K which is in general unknown and must be inferred in order to calculate B k .
[0066] Any inference methodology must allow for the uncertainty caused by unknown influences on the system, so we have also extended our model to include “process noise” via the vector n x , which is normally distributed with mean zero and scale matrix Q. This formulation follows standard lines, such as that used for the Kalman Filter. Typically, Q is diagonal with entries chosen by estimating the likely random variation in the corresponding hidden temperature states. A value of Q that works well is discovered by tuning the Kalman Filter in conventional ways. An example is given in the worked example below.
[0067] The hidden state is x k —named as such because it can never be directly measured—we only know about it via a measurement y k =Hx k +n y . The matrix H characterises the relationship between our measurement and the hidden state, and is dependent on the measurements we actually have from our system. For the example above, H could be the vector [1 0 0] indicating that we are just measuring room temperature. In the formulation below, we assume that H is known (although the process could be easily extended to infer H as well, if for example we think our temperature measurement is influenced by the temperature of a wall as well as the air temperature). We also allow for the measurement being subject to a noise n y which is normally distributed with mean zero and scale matrix R. Typically, R is diagonal with entries reflecting the accuracies of the sensors used to measure temperatures, for example 0.1 C accuracy for a room temperature sensor, means R=100 (=1/sigmâ2).
Data Buffering and Selection
[0068] Before we describe in detail our method for inferring r, we first explain how a block of measurement data is selected as an input to this process—our method works block-wise on an input buffer of time-series data (and produces an updated value of the vector r as a result of processing this buffer).
[0069] The measurement data can come from a variety of possible sources (see example scenarios above and applications below). Most important is the set of measured temperatures from the inside the house, but generally we will also include what we know about external conditions and the energy input to the house—for example, external conditions and whether heat was requested from a boiler.
[0070] Rolling buffer. To produce the input buffer, we must maintain a rolling buffer of temperature measurements y k , where data older than the duration of the buffer (for example, a week) is discarded. The rolling buffer is kept updated at a fixed time interval (for example, every 5 minutes) as the measurements arrive, and then at a much longer timer interval (for example, every night) the thermal parameter learning process is executed using the contents of the buffer. The time period to which the data in the buffer corresponds (i.e. the period over which the stored temperature data was obtained) is the data acquisition period.
The thermal parameter learning process takes quite a lot of computational time, and must always take place on the buffer as a whole, which is why it is convenient only to execute it every night. When the system is first started, the input buffer may only be a day long (for example), and then gradually extend in length as data becomes available, until it reaches the maximum length of the rolling buffer (a week for example). After the first few days, the learning process may be executed less frequently than at first (e.g. every few nights), to reduce usage of computational time. In effect, we always update our estimates of the thermal parameters using the last week's data, which enables changes to the building or its environment to influence the model in a timely fashion. We can choose not to carry out a learning process under certain conditions (too warm outside, missing data). We can choose to mark parts of the input buffer as “invalid,” for example when measurements have not been received or are known to be false (e.g. pipe temperatures when there is no water flow).
[0077] When we have identified a set of data from the rolling buffer to form our input buffer, we follow the procedure in the next section to update our thermal parameters using it.
Bayesian Inference Approach
[0078] This is used to infer a value of the thermal parameter vector r using the data from the input buffer. The process for doing this is outlined in FIG. 3 and qualitatively follows the steps below (in relation to symbols introduced above):
1. Start with a first guess for a sensible value of r (or using the value of r calculated from a previous thermal parameter learning calculation). The first guess of r may come from a fixed set of values that we know is typical of the type of heating system under consideration (e.g. conventional fossil-fuel boiler), or by guessing using physical intuition the likely time constants (e.g. a several hours to heat up a wall) or by the method described in PCT Patent Application No. PCT/GB2013/050376 from measured data. The value only needs to be approximately right (order of magnitude). 2. Infer hidden state {x k } from the measurements {y k } over the time period. 3. Infer {A k } and {B k } and the set of hidden states {x k }. 4. Deduce A d from {A k }, and separate {B k } into B d and F d , given knowledge of E and T E . 5. Deduce new value of r from A d , B d , and F d as their relationship is defined by the house model.
[0084] This is the essence of the process conceptually, but in practice we actually need to go directly from x to r.
[0085] We now describe more explicitly the information that we require and what the exact steps are to calculate or update r.
[0086] The input buffer consists of the following sets of vectors (see also FIG. 3 again),
[0000] where n is the length of the buffer in time steps:
{y k } for k=1:n , the temperature measurement vector at each time step {T E,k } for k=1:n , the measured external conditions {P k } for k=1:n , the information we know about control signals given to the heating system.
[0090] We use a forward-filter-backward-sampling (FFBS) method to do this stage of the inference. A standard Kalman filter gives an estimate of the hidden state, but it is biased towards preceding measurements; when we have the whole of a time period logged, measurements that come after a particular time are also useful in telling us something about the hidden state at that time. The FFBS method involves running a Kalman filter forward in time (forward filtering), recording the mean and covariance at each time step, and then sampling backwards in time using these statistics. (see also FIG. 3 ). The paper “A Tutorial on Particle Filtering and Smoothing” by Doucet & Johansen provides a description of this type of procedure.
Forward Filtering
[0091] The first step is to use a forward-filtering approach to infer a number of intermediate quantities: The mathematics centres around the formula
[0000] P ( x k |y 1:k )∝∫ dx k−1 P (y k |x k ) P ( x k |x k−1 ) P ( x k−1 |y 1:k−1 )
[0000] and for our model we have:
[0000] P ( y k |x k )˜exp−½ {( y k Hx k ) T R ( y k −HX k )}
[0000] P ( x k |x k−1 )˜exp−½{( x k −A k x k−1 −B k ) T Q ( x k −A k x k−1 −B k )}
[0092] For forward filtering, we wish to express our understanding of the hidden state as a Gaussian probability distribution:
[0000] P ( x k |y 1:k )˜exp−½ {( x k −μ k ) T S k ( x k −μ k )}
[0000] where the matrices {S} and the vectors {μ} are yielded by (i.e. one of the outputs of) the forward filtering process.
{μ k } for k=1:n , where μ k is the mean of the inferred Gaussian probability distribution for the hidden state x k {S k } for k=1: n where S k is the scale matrix of the Gaussian inferred probability distribution for the hidden state x k {E k } for k=1: n where E k is estimated actual energy input to the house model at time k, is derived from {P k } and deductions about evolved temperatures. The way in which this is done (alongside the forward filetering) is described in the section ‘Energy Inference’ below.
[0096] The standard Kalman filter equations provide a method of calculating {S k−1 , μ k−1 }→{S k , μ k } using the measurement values, and so we can apply these iteratively starting with a sensible guess for the initial hidden state μ 1 (e.g. wall and pipes are the same temperature as the room) and S 1 (e.g. S 1 =Q). For data marked as “invalid” we use only the prediction step of the Kalman filter.
Energy Inference
[0097] The above processes are derived from the standard literature on FFBS. However the vector B k is dependent on the energy input to the house E k which is in general unknown, and may not have a linear relationship to other parameters so cannot be included straightforwardly as an additional hidden variable in the inference. The approach used in this method is to infer E k qualitatively from the current state x as part of the Kalman (forward) filtering, taking into account the control signals that are one of the recorded inputs, and the current estimate of the hidden state.
[0098] The value of E (for this timestep k) determined by the forward filtering is then used in the backward sampling as well, although this could be further extended to a probabilistic model for E according to the previous and next states.
[0099] In most scenarios the energy input will be unknown, as it represents the thermal energy delivered by the heating source to the heat delivery system (e.g. from boiler to the water in the radiators)—but we require a value of E in order to use our house thermal model. Our approach is to use the value of the hidden state during the forward-filtering, together with what we know about control signals P, to estimate a value for E. For example, for a conventional boiler, if the “hidden” water temperature is too high (e.g. >70 C.), we can infer that the boiler will no longer be firing.
[0100] A related complication is that the unit E is measured in will vary from scenario to scenario, as often we will only have a relative measurement (such as the fraction of full power the heating system is running at).
[0101] To clarify, we provide two example scenarios to illustrate our approach to energy inference.
Conventional Boiler Example.
[0102] For a conventional boiler, E is a dimensionless quantity giving the fraction of its maximum output power the is operating at (as a single scalar value). For a non-modulating gas boiler, this will be 1 when the gas flame is on and 0 when the gas flame is off. When E enters our house model equations, it will always be multiplied by an r parameter (r 6 in Eqn 2), which characterises the effect the boiler at full power has on the heating system. This r param will be learned and will determine the temperature gradient of the water temperature (in isolation) when the energy source is at full power (e.g. r 6 =180° C./hr).
[0103] However, we cannot in general directly measure the state of the gas flame or E—all that is known is the “heat request” control signal to the boiler, which constitutes our P measurement in the buffers above. The boiler will turn off (or modulate) the gas flame to ensure a maximum water temperature is not exceeded, so we use the following logic to infer E from P:
If control signal P=0, we know E=0. If the control signal P=1, we use the water temperature component of the hidden state, as filtered at the current time in the forward filtering process. We infer that E=1 if the water temperature in the boiler is below an assumed threshold (say 70 C), otherwise E=0.
[0106] We have no need to know true powers (e.g. in kilowatts) as all we need to know is how to relate boiler heat requests with their effect on the heating system (as best as we can infer).
Heat Pump Example.
[0107] A heat pump is a rather different scenario, as we are likely to be able to measure the input electrical power to the heat pump (via an electricity meter). However, we still cannot determine E immediately, since E is the output thermal power from the heat pump to the heat delivery system. For a heat pump we can use a model for its “coefficient of performance” (COP), the ratio of the output power to the input power, to estimate E from the input power. The COP varies depending on the water temperature, so like the boiler we used the water temperature component of the inferred hidden state to deduce the COP and thus E.
[0108] E will be a value in kilowatts, which means that the corresponding component of r will have units of degrees per unit time per kilowatt. This means that we will be able to use r as before to infer as best as we can the thermal effect on the house of a kilowatt of electricity into the heat pump.
[0109] Our method would also be applicable if there was no electricity meter installed to measure the input power. In this case, we would return to the dimensionless E, and infer its value similarly to a boiler using the control signal and a few assumptions about the operation of the heat pump at different water temperatures. For the case of a heat pump controlled by specifying target water temperature, we might not need to include E in the inference at all (and just learn about the relationship between the water temperature and other temperatures in the house).
Backwards Sampling
[0110] The next step after forward filtering is to use a backward-sampling approach to sample values of the hidden state x k from the above forward-filtered quantities:
[0111] We wish to backwards sample using {S} and {μ}. We denote X as the sampled value and x as the parameter in a probability distribution. From the above equations we find:
[0000] X k−1 ˜exp−½{( X k −A k x k−1 −B k ) T Q ( X k A k x k−1 −B k )+( x k−1 −μ k−1 ) S k−1 ( x k−1 −μ k−1 )}
[0000] which can be written as
[0000]
X
k
-
1
~
exp
-
1
2
{
(
x
k
-
1
-
(
S
k
-
1
+
A
k
T
QA
k
)
-
1
(
S
k
-
1
μ
k
-
1
+
A
k
T
Q
(
X
k
-
B
k
)
)
)
T
(
S
k
-
1
+
A
k
T
QA
k
)
(
x
k
-
1
-
(
S
k
-
1
+
A
k
T
QA
k
)
-
1
(
S
k
-
1
μ
k
-
1
+
A
k
T
Q
(
X
k
-
B
k
)
)
)
}
where the mean and the scale matrix are for sampling the multi-dimensional Gaussian are made explicit. We can apply standard methods to take a multivariate Gaussian sample from this distribution.
{X k } for k=1:n , where X k is a particular, randomly-sampled value of the hidden state random variable x k .
[0114] Thus we now have the output X k from the forward-filtering-backwards sampling steps.
[0115] The next step is to sample a new thermal parameter vector r using this sampled set {X k }
[0116] At this point we have a sampled hidden state X at every point in time in our buffer, and wish to use this state to sample the thermal parameters of the house r. We wish to determine the form of P(r|X 1:k )
[0117] Using Bayes' theorem and introducing a prior for r:
[0000] P ( r|X 1:k )∝ P ( X 1:k |r ) P ( r )= P ( X 1 ) P ( r )Π k P ( X k |X k−1 , r )
[0118] We ignore P(x 1 ) because it has no real r dependence, and the likelihood term can be written:
[0000] P ( X 1:k |r )˜exp−½{Σ k ( X k −A k ( r ) X k−1 −B k ( r )) T Q ( X k −A k ( r ) X k−1 −B k ( r ))}
[0119] We now have to make the r-dependence of A and B explicit. First, we separate them back into the differential forms above:
[0000]
X
k
=
A
k
X
k
-
1
+
B
k
=
(
I
+
Δ
tA
d
)
X
k
-
1
+
Δ
tB
d
E
k
+
Δ
tF
d
T
E
,
k
so
X
k
-
A
k
X
k
-
1
-
B
k
=
Δ
t
(
X
k
-
X
k
-
1
Δ
t
-
(
A
d
X
k
-
1
+
B
d
E
k
+
F
d
T
E
,
k
)
)
and
thus
X
k
-
A
k
X
k
-
1
-
B
k
=
Δ
t
(
X
k
-
X
k
-
1
Δ
t
-
D
k
r
)
[0000] defining the matrix D. For the specific example we considered above in Eqn 2,
[0000]
D
k
=
(
X
k
,
2
-
X
k
,
1
T
k
,
E
-
X
k
,
1
X
k
,
3
-
X
k
,
1
0
0
0
0
0
0
X
k
,
1
-
X
k
,
2
0
E
k
0
0
0
0
X
k
,
1
-
X
k
,
3
0
)
[0000] where the addition numeric suffix on X indexes the vector components. D thus intuitively give the differences in temperature between different model states that affect other model states when multiplied by each element of r, thus separating the effects of the different components of r, and representing them in s a linear matrix form. Note the matrix multiplication in the term D r.
[0120] Now we have a multivariate Gaussian likelihood function for r:
[0000]
P
(
X
1
:
k
r
)
~
exp
-
1
2
{
∑
k
(
X
k
-
X
k
-
1
Δ
t
-
D
k
r
)
T
Δt
2
Q
(
x
k
-
X
k
-
1
Δ
t
-
D
k
r
)
}
[0121] The intuition here is that we should favour values of r that mean that the temperature gradient (ΔX/Δt) match what the model predicts (D r). We need to now apply the sum over k to get a multivariate likelihood distribution for r:
[0000]
P
(
X
1
:
k
r
)
~
exp
-
1
2
{
r
T
(
Δ
t
2
∑
k
D
k
T
QD
k
)
r
-
(
Δ
t
2
∑
k
(
X
k
-
X
k
-
1
Δ
t
)
T
QD
k
)
r
-
r
T
(
⋯
)
T
}
~
exp
-
1
2
{
r
-
ρ
)
T
U
(
r
-
ρ
)
}
[0000] defining scale matrix U and mean vector P. The scale matrix U includes correlations between different r parameters, which would be very hard to represent using less complex mathematics.
[0122] At this point, we have a mathematical equation for the (likelihood) probability distribution of the thermal parameter vector r (given the input data buffer). The final step of the process is to take a sample from this distribution to use as the output of the process.
[0123] In order to sample r, we need to include its prior for a Bayesian treatment (the formula above is the likelihood). All components of r are positive (by the laws of physics)—for example, the hidden wall temperatures have slow time constants and low r values and are thus driven towards zero, and prior “pressure” is needed to keep them physical and stop instability. We choose independent gamma priors for r:
[0000] P ( r|{m j , θ j })˜Π j r j m j −1 e −r j /θ j
[0000] and thus the final posterior distribution for r that we need to sample from is the following function:
[0000]
P
(
r
x
1
:
k
,
{
m
j
,
θ
j
}
)
~
exp
{
-
1
2
∑
ij
r
i
U
ij
r
j
+
∑
ij
ρ
i
U
ij
r
j
-
∑
i
r
i
/
θ
i
+
∑
i
(
m
i
-
1
)
log
r
i
}
(
11
)
[0124] Our method for sampling this function is to expand the log term around the mode of the distribution, and then use rejection sampling on the resulting multivariate Gaussian. The output of this mathematical process is a single vector value for the new sampled r.
[0125] When sampling from the resulting posterior the approach adopted in this method is to (a) calculate the mode of the distribution and (b) “rejection sample” from a multivariate Gaussian centred at the mode. The methodology that provides a sample from the posterior probability distribution in Eqn (11).
[0126] Rejection sampling is a standard technique in the literature, which enables samples to be drawn from a distribution that cannot be analytically sampled from, by sampling from a similar proposal distribution (that can be analytically sampled from) and rejecting samples if the desired distribution has lower probability than the proposal distribution. This is done in a way that can guarantee mathematically that samples are representative of the desired distribution. The only downside is that a vast number of samples might need to be rejected, but this can be avoided with careful choice of proposal distribution, which is what we describe here.
Rejection Sampling
[0127] We wish to sample r from the following probability distribution (duplicate of Eqn 11), where U, ρ, θ and m are known (from the previous calculations in Appendix B).
[0000]
P
(
r
x
1
:
k
,
{
m
j
,
θ
j
}
)
~
exp
{
-
1
2
∑
ij
r
i
U
ij
r
j
+
∑
ij
ρ
i
U
ij
r
j
-
∑
i
r
i
/
θ
i
+
∑
i
(
m
i
-
1
)
log
r
i
}
[0128] We use a Newton-Raphson method to solve for the mode (maximising the exponent).
[0000]
0
=
-
∂
P
∂
r
l
~
∑
i
U
il
(
r
i
-
ρ
i
)
+
1
/
θ
t
-
(
m
l
-
1
)
/
r
l
[0000] with Hessian matrix H=U+I.(m j −1)/r j 2 where j indexes the diagonal in the second term. The step δ r satisfies Hδr=−[Eqn 12] above, and this is solved straightforwardly by linear elimination. The starting point for the Newton-Raphson iterations is the current r used in the first FFBS stage.
[0129] Suppose that the mode we have found is at r=v. We now expand the log term around this point:
[0000] log r i ≅logν i +( r i −ν i )/ν i −( r i −ν i ) 2 /ν i 2
[0130] We now deliberately ignore the quadratic term, as it will ensure that our proposal density is greater than the true density at all points, and so the log term adds an additional term (m j −1)r i /ν i to the exponent. Our proposal density becomes:
[0000] P ( r|x 1:k , {m j , θ j })˜exp−½{( . . . ) T U ( r−ρ−U −1 (( m j −1) r j /ν j −1/θ j ))}
[0131] So for our rejection sampling, we first sample r from the above Gaussian distribution, and the rejection criterion is simply the ratio of the true log to the approximated log (with an implicit multiplier such that the probability densities are equal at the mode):
[0000] a =exp Σ j ( m j −1)[log r j −(logν j +( r j −ν j )/ν j )]
[0132] Hence we sample a uniform random number 0≦u<1 and if u<a we accept the sample, otherwise we re-sample from the Gaussian above. The Gaussian can inevitably produce negative samples; these are rejected straight away before calculating a.
[0133] Additional steps are required if the matrix U is not of full rank (this occurs for example if there is never any heat input to the system): the process is to eliminate dimensions until U is of full rank, and leave these components of r unchanged in that learning cycle.
[0134] It will be appreciated that the above process for sample r by rejection sampling is within the parameter sampling block of FIG. 3 , while the iteration of r as a whole is represented by the cycle/loop illustrated in FIG. 3 .
Overall Iterations
[0135] After r has been sampled, we then iterate by starting again at the first step (forward-filtering) with the new value of r, and repeat the whole process a number of times (e.g. 30).
Optionally, we can start the iterations off with an assumption that the process noise is large, and gradually decrease it as a type of simulated annealing, in order to ensure the process is not trapped near the initial values. Optionally, we can make a decision at this point as to whether the new value of r is sensible. For example, we could put bounds on values of r from physical knowledge of the house, or we could analyse for periods of unexpected heat (e.g. from an open fire or log burner) that would distort the results. This decision is completely separate from the acceptance criterion used in the rejection sampling in (the latter is a completely mathematical construction).
[0138] The procedure described above constitutes a Bayesian “Gibbs sampling” process for inferring {X k } and r. The Bayesian formulation of the original problem is the probability distribution P(x 1:n , r|y 1:n ), and we sample {X k } and r from it. The Gibbs sampling process is to start with an initial guess for r, and then use this to sample from P(x 1:n |y 1:n , r), which is in fact a standard task known as “smoothing” and the method we chose is “forward-filtering-backward-sampling” (FFBS). The second Gibbs step is to sample r in turn given the sample {X k }, from P(r|x 1:k ), y is no longer required as it has no more information now we have an (assumed) value of x.
Use of Results
[0139] FIG. 4 helps to illustrate possible use of the thermal property data obtained by the method according to the invention. This information can be used to improve temperature control or provide useful feedback to the householder about the management of their house's heating system. The overall concept is a feedback loop of measuring temperatures, analysing them, and changing the way heating is managed as a result.
[0140] The outputs of the “thermal parameter learning” block are used to provide useful insight to a consumer, as well as automatically as part of a heating control system. The thermal parameter learning block resides on a “home energy management system” consisting of a computer with an ability to store and process data, and optionally interact with a user via a display and input ability (e.g. touchscreen).
EXAMPLE SCENARIOS
Possible Inputs:
[0000]
Temperature measurements: from a room air sensor, from an external sensor, from pipe sensors (e.g. measuring the temperature of water in the heating system), or other sensors (e.g. reflecting the temperature of bricks in a storage heater).
External weather data provided from a weather station (either locally or via an internet feed): temperature, solar irradiation, or any other value that can provide a thermal influence on the house.
Control signals from the heating control system, such as heat requests to the boiler, or power consumption of the heating system, etc. Ideally, both input and output energy of the heating system is measured, but often only control signals are available, and sometimes nothing is available (e.g. if a monitoring system is being used that is separate to an existing heating controls system).
[0144] Not all of these inputs are required for the invention to work; we describe below a number of different scenarios for its deployment.
[0145] Example: gas boiler, we measure room temperature and external temperature (possibly via internet weather station), and record the control signals (on/off) given to the boiler.
[0146] Example: gas boiler, we measure room temperature and external temperature (possibly via internet weather station), but have no access to control signals as we're in a monitoring only scenario.
[0147] Example: heat pump, we measure room temperature and external temperature as for the boiler, and also measure flow & return pipe temperatures and the power consumption of the heat pump.
[0148] Example: storage heater, we measure room temperature and external temperature again, the power consumption used to charge the storage heater, and also the control signal given to the discharge vent (requires storage heater extension in Appendix D)
More accurate inference is possible with the addition of information about the temperature of the bricks inside the storage heater. For example, we could use a sensor attached to the outside of the storage heater, which measures a temperature that is influenced by the warmth of bricks inside. An advantage of our methodology is that it allows this indirect “influence” to be utilised. If control signals are unknown (i.e. no information on charge or discharge from the storage heater), our methodology can still be used (this would require something similar to the particle-filtering extension).
[0151] Example: any of the above scenarios could be easily extended to allow for solar irradiation (as measured by an internet weather station) by including an additional external influence term in the house model and learning the extent to which the room temperature is warmed by natural sunlight. The influence of other weather data could be included equivalently.
[0152] Example: any of the above scenarios could be easily extended to a multiple room configuration, whereby room temperature sensors are placed in each room and the house model is expanded to include states for each room and the connections between them. Our invention would then enable us to learn how much the thermal response of different rooms are correlated and which rooms are losing the most heat to outside.
[0153] Our thermal learning method provides a way in which a block of data from a house can be processed in order to produce a matched model of the thermal response of the house. This model can then be used to make predictive deductions about the house, for example how temperatures will change in response to particular control signals or energy inputs, and we give some example applications in later sections.
[0154] As described above, the method can be applied to any situation where there is a linear house model and a means of inferring the thermal input provided by the heating system, given the history of control signals.
[0155] There are four areas where we have extended the invention to cover further applications:
(1) Storage heaters. Storage heaters use a bank of bricks to store heat from cheap overnight electricity and release it when required. They are controlled by two signals: one to charge the bricks, and one to adjust the position of the discharge vent. We model the storage heater as a radiator with a varying thermal conductance to the room (i.e. r 1 and r 4 in our example above), from a minimum value (representing how much heat the bricks lose when the vent is shut) to a maximum value (representing the most heat it can deliver when the vent is fully open).
[0157] When the discharge vent of a storage heater is moved by a control algorithm, the thermal model of the house is changed, so special treatment is required: (a) we need to adapt the model according to this control signal as part of the “smoothing” process when sampling X (adapting the forward filtering backwards sampling procedure), and (b) we need to learn the ratio between the heat transfer coefficient when the vent is fully open and when the vent is fully closed. The control parameter directly affects the evolution matrix A, and there are two different thermal characteristics to learn: the thermal conductivities at minimum and maximum vent positions.
[0158] A storage heater with a variable vent position v can be modelled by the slightly adapted propagation matrix:
[0000]
A
d
=
(
-
vr
1
-
r
2
-
r
3
vr
1
r
3
vr
4
-
vr
4
0
r
5
0
-
r
5
)
[0159] The vent multiplier v satisfies v min <v<1 (without loss of generality, as the unaltered r parameter represent the maximum vent position). This is related to the vent control signal v c (which satisfies 0≦v c ≦1) by v=v min (1−v c )+v c . We can see that A (and thus D also) is now non-linear in the effective parameter vector [r, v min ] and so our formalism cannot readily be extended to the storage heater scenario.
[0160] Our approach is to include an additional Gibbs sampling step for v min :
Firstly, assume a value for v min or use the previously learned value, and sample X assuming this value (calculating changes in A along the way using the known control signal v c and the assumed v min to calculate v) using the same method as Appendix A. Secondly, sample r as previously, again using the same method as previously (Appendix B), calculating D as follows since v is assumed known.
[0000]
D
=
(
v
(
T
2
-
T
1
)
T
E
-
T
1
T
3
-
T
1
0
0
0
0
0
0
v
(
T
1
-
T
2
)
0
E
0
0
0
0
T
1
-
T
3
0
)
Thirdly, we sample v min given the previously sampled X and r values. This requires new mathematics where we factorise D into two matrices such that D=D+v min +D − . These matrices are:
[0000]
D
+
=
(
T
2
-
T
1
T
E
-
T
1
T
3
-
T
1
0
0
0
0
0
0
T
1
-
T
2
0
E
0
0
0
0
T
1
-
T
3
0
)
v
c
and
D
-
=
(
T
2
-
T
1
T
E
-
T
1
T
3
-
T
1
0
0
0
0
0
0
T
1
-
T
2
0
E
0
0
0
0
T
1
-
T
3
0
)
(
1
-
v
c
)
[0000] and known at each timestep (given the temperature state sample and the control signals).
[0164] Recall the likelihood function used previously:
[0000]
P
(
X
1
:
k
|
r
)
∼
exp
-
1
2
{
Σ
k
(
X
k
-
X
k
-
1
Δ
t
-
D
k
r
)
T
Δ
t
2
Q
(
X
k
-
X
k
-
1
Δ
t
-
D
k
r
)
}
[0165] Rewriting to look at ν min influence:
[0000]
X
k
-
X
k
-
1
Δ
t
-
D
k
r
=
(
X
k
-
X
k
-
1
Δ
t
-
D
k
+
r
)
-
v
min
(
D
k
+
r
)
we
get
P
(
X
1
:
k
|
r
,
v
min
)
∼
exp
{
-
1
2
K
v
min
2
+
Lv
min
}
where
K
=
Σ
k
r
T
D
k
-
,
T
Δ
t
2
QD
k
-
r
and
L
=
Σ
k
r
T
D
k
-
,
T
Δ
t
2
Q
(
X
k
-
X
k
-
1
Δ
t
-
D
k
+
r
)
[0000] (being careful about factors of 2)
[0166] We choose a truncated Gaussian prior for ν min
[0000]
P
(
v
min
)
∼
exp
-
(
v
min
-
μ
)
2
2
σ
2
:
0
<
v
min
≤
1
[0000] and thus the posterior
[0000]
P
(
v
min
|
X
1
:
k
,
r
)
∼
exp
{
-
1
2
(
K
+
1
2
σ
2
)
v
min
2
+
(
L
+
μ
2
σ
2
)
v
min
}
=
exp
{
-
1
2
av
min
2
+
bv
min
}
[0000] defining a and b. We are now ready to actually sample ν min , which we do by first sampling u as a uniformly distributed random number between 0 and 1, and then calculating
[0000]
v
min
=
b
+
2
a
erf
inv
{
u
erf
(
a
-
b
2
a
)
+
(
1
-
u
)
erf
(
-
b
2
a
)
}
a
[0000] where “erf” is the standard error function and “erfinv” is the inverse of the standard error function.
Finally, we finish the symmetrical Gibbs process by resampling r again with the new ν min parameter.
[0168] At the end of the process we have an updated estimate for the minimum vent position thermal conductivity as a multiplier of the corresponding r parameters (in this case, r 1 and r 4 ).
(2) Unknown Control Signals.
[0169] It is desirable to learn about the thermal properties of the house in the situation when are only able to monitoring temperatures independently of the control system—in this case we do not know the control signals given to the heating system, and are thus unable to directly infer the power provided to the house. However, in some circumstances temperature measurements give strong clues as to when the heat input occurs—for example a gas boiler is powerful enough that temperatures rise rapidly. This is a significantly harder inference problem, but can be solved within the framework of this invention. We will refer to a boiler scenario below, but it is more widely applicable as well.
[0170] For this inference we need to allow for the boiler firing a while before there is any measurable effect on the room temperature. So as part of the inference process, at each time step we effectively need our simulation to predict the consequences of both the boiler firing and not. Naively, this leads to a impossibly large tree of possibilities after a short time, but we can make progress using a technique called a particle filter. This works by representing the state with a fixed large number of particles which evolve with time, each has a “weight” which is updated according to how successful the particle is at explaining the data. Every so often, we kill off the unsuccessful particles and “breed” the most successful particles.
[0171] We use these particles just to represent the boiler on/off state, and retain the Kalman filter approach for temperatures—each particle has a Kalman filter associated with it, and this bank of Kalman filters interact when the particles are resampled. The model is a “conditionally linear Gaussian model”—the evolution equation switches depending on the boiler firing state. We follow the approach of Douchet & Johansen “Rao-Blackwellised particle filtering”.
[0172] The sampling of r as described above is unchanged—the particle filter method is used to sample the model state X instead of the FFBS approach.
[0173] Each particle evolves independently, and we record at each time step the weight of each particle, its power decision, and its Kalman mean. The covariance is identical across particles (no dependence on B in the maths) so we just need to record this once at each timestep.
[0174] Introducing u k for the boiler firing variable, we wish to sample from:
[0000] P ( x k ,u k |y 1:k )∝ P ( x k |y 1:k , u k ) P ( u k |y 1:k )
[0175] So our inductive probability is a combination of the Kalman filter in the presence of a known firing (as above) and a probability of firing (second term) represented by the particle distribution.
[0176] Our particle update step is:
[0000] P ( u k |y 1:k , u 1:k−1 )∝ P ( y k |y 1:k− , u 1:k ) P ( u k |u k−1 )
[0000] ∝∫ dx k−1 , dx k P ( y k |x k ) P ( x k |x k−1 , u k ) P ( x k−1 |y 1:k−1 , u 1:k−1 ) P ( u k |u k−1 )
[0000] which is the same as the standard Kalman filter equations with x k integrated out. This is the key maths: the residual term is from the Kalman step is usually left out, but there is still dependence on B k in this term, which is in turn dependent on u so we need it in this case.
[0177] Note the appearance of P(u k |u k−1 ): this is the prior probability of one boiler state given the previous; this is quite important as it allows us to make it more likely for the boiler to stay in its current state and discourage the algorithm from rapidly cycling the boiler. So for example, P(0/0)>P(1/0), to express the fact that the boiler stays off much more frequently than it get turns on.
[0178] Taking care with all the residual terms we can derive the following relationships in a similar fashion to the Kalman Equations
[0000]
P
(
u
k
|
y
1
:
k
,
u
1
:
k
-
1
)
∝
exp
-
1
2
{
(
y
k
-
Hx
k
pred
(
u
k
)
)
T
W
k
(
y
k
-
Hx
k
pred
(
u
k
)
)
}
P
(
u
k
|
u
k
-
1
)
[0000] where W is the Kalman residual covariance (inverted) and x k pred (u k )=A k x k−1 +B k (u k ) is the predicted state.
[0179] This is all we need to implement a particle filter. We weight particles at k−1 according to Σ u k P(u k |y 1:k , u 1:k−1 )(this is in effect one step ahead, taking advantage of the “auxiliary particle filter” concept—this means we can avoid throwing out half our particles each step), and we sample u k with weights on 0 and 1 according P(u k |y 1:k , u 1:k−1 ). After sampling u k we can Kalman filter each particle as previously, as all u 1:k are known for each individual particles.
[0180] The output from forward filtering is a power level (0 or 1), weight, and temperature state (mean) for each particle at each moment in time, plus a covariance matrix at each point in time for all particles. The weight reflects the importance of that particle.
Particle Filter Step-by-Step Instructions
[0181] (For the specific example of boiler firing)
Forward Filtering
Initial Values:
[0182] S 1 =Q as for the normal case (there is a single value, rather than one for every particle)
[0183] μ 1,p is a sensible guess for the initial hidden state, for each particle p=1 . . . n p .
[0184] All particles have equal weight w 1,p =1/n p .
For Each k:
[0000]
Calculate updated error scale matrix S k from S k−1 using the normal Kalman filter equations, keeping a note of the residual covariance matrix w k −1 and the Kalman gain matrix K k .
For each particle p:
1. Calculate the predicted state both in the presence and absence of boiler firing:
[0000] μ k,p pred,u=0 =A k μ k−1,p +B k (E=0)
[0000] μ k,p pred,u=1 =A k μ k−1,p +B k (E=1)
[0000] where we are using as before the functional dependence of B on the energy input E.
2. Calculate the residual for both cases:
[0000]
z
k
,
p
u
=
0
=
y
k
-
H
μ
k
,
p
pred
,
u
=
0
z
k
,
p
u
=
1
=
y
k
-
H
μ
k
,
p
pred
,
u
=
1
3. Calculate the updated state estimate for both cases:
[0000]
μ
k
,
p
new
,
u
=
0
=
μ
k
,
p
pred
,
u
=
0
+
K
k
z
k
,
p
u
=
0
μ
k
,
p
new
,
u
=
1
=
μ
k
,
p
pred
,
u
=
1
+
K
k
z
k
,
p
u
=
1
4. Calculate the likelihood weighting for both cases:
[0000]
l
k
,
p
u
=
0
=
exp
(
-
1
2
z
k
,
p
(
u
=
0
)
,
T
W
k
z
k
,
p
u
=
0
)
l
k
,
p
u
=
1
=
exp
(
-
1
2
z
k
,
p
(
u
=
1
)
,
T
W
k
z
k
,
p
u
=
1
)
Note that here it is advantageous to work in logarithms and shift the ratio of these to to avoid the limits of machine precision.
5. Calculate prior probabilities P(u k =0) and P(u k =1) for each particle according to previous state u k−1 , using model P(u k |u k−1 ), and taking care of model behaviour at maximum water temperature.
6. Re-weight particles against either outcome:
[0000]
w
k
,
p
=
w
k
-
1
,
p
*
(
l
k
,
p
u
=
0
P
(
u
k
=
0
)
+
l
k
,
p
u
=
1
P
(
u
k
=
1
)
)
Renormalise particles so Σ p w k,p =1 and calculate whether Σ p w k,p 2 >2/n p , and if it is, re-sample particles according to standard particle filter equations: choose n p random particles with probability proportional to their weight, give these ones equal weight, and discard the rest.
For each particle: Randomly decide whether boiler fires, proportionally to l k,p u=0 P(u k =0) and l k,p u=1 P(u k =1), and taking care of maximum water temperature, and record the choices as E k,p , and also record the state μ k,p according to the firing choice.
Moving Onto Backward Sampling, We Used Previously
[0196]
X
k
-
1
∼
exp
-
1
2
{
(
…
)
T
Q
(
X
k
-
A
k
x
k
-
1
-
B
k
)
+
(
…
)
T
S
k
-
1
(
x
k
-
1
-
μ
k
-
1
)
}
X
k
-
1
∼
exp
-
1
2
{
(
…
)
T
(
S
k
-
1
+
A
k
T
QA
k
)
(
x
k
-
1
-
(
S
k
-
1
+
A
k
T
QA
k
)
-
1
(
S
k
-
1
μ
k
-
1
+
A
k
T
Q
(
X
k
-
B
k
)
)
)
}
[0000] but there are additional terms that don't involve x k−1 but do involve B k which is a function of u k :
[0000]
exp
-
1
2
{
μ
k
-
1
T
S
k
-
1
μ
k
-
1
+
(
X
k
-
B
k
)
T
Q
(
X
k
-
B
k
)
-
(
…
)
T
(
S
k
-
1
+
A
k
T
QA
k
)
-
1
(
S
k
-
1
μ
k
-
1
+
A
k
T
Q
(
X
k
-
B
k
)
)
}
[0197] This provides the weighting to sample a particle for the next step backwards (B k is a function of u k so we evaluate for both possibilities); this determines the next mean and the previous (in time) power.
We have to be very careful about which index corresponds to which power level and which weight and the order of doing things; the kth weight is for x k and for the power which transitions between k−1 and k. We also need to be careful of the difference between request and actual boiler power, because the transition probability only applies to the request—we want to limit cycling for the request but not for actual power. This can be applied with some extra logic in both FF and BS.
Backward Sampling
Initial Values:
[0200] Hidden temperature state X n k , sampled from multi-dimensional Gaussian specified by scale matrix S n k and mean μ n k , p , where we have chosen p by sampling a particle (taking account of weights at this time-step).
[0201] For each k (backwards, starting with n k−1 ):
For each particle p:
1. Calculate G k,p =S k μ k,p +A k+1 T Q(X k+1 −B k+1,p ) where B k+1,p is calculated using the previously sampled E k+1,p (in forward filtering). 2. Calculate
[0000]
V
k
,
p
=
exp
-
1
2
{
μ
k
,
p
T
S
k
μ
k
,
p
+
(
X
k
+
1
-
B
k
+
1
,
p
)
T
Q
(
X
k
+
1
-
B
k
+
1
,
p
)
+
G
k
,
p
T
(
S
k
+
A
k
+
1
T
QA
k
+
1
)
-
1
G
k
,
p
}
3. Calculate posterior weight h k,p =w k,p V k,p P(E k,p |E k+1,p ) where the last term is dependent on model transition probabilities {P(u k |u k−1 )} and water temperature state, again using logarithmic scaling on V k,p to take out the normalisation constant (i.e. subtract largest value as logarithm).
Sample a particle from the set with weights proportional to h k,p . We then use the Kalman mean μ k,p and power decision E k,p of this particle p as the basis of the backwards sampling for this step. X k Is sampled as before (i.e. non-particle-filter) using these values.
[0207] The output of the backward sampling is a single sample {X k }, {u k } (as we have sampled a particular particle at each time step)—and then this can be used exactly as previously for sampling r.
Note that this process is readily extendible to scenarios other than the boiler firing example described here—we just need a modelled probability distribution akin to P(u k |u k−1 ) which is used to weight and sample particles. A discrete distribution is likely to be sufficient, and makes the latter step easier. (3) No control signals but measure water temperature. An alternative approach to the scenario where we do not have access to control signals is to monitor the flow/return pipes and learn the thermal response of the house to water temperature as an external influence. This would be a better approach in the case of a heat pump, for example, where these temperature measurements are likely to be available. (4) Hot water control. A similar approach can be used to characterise the thermal dynamics of a hot water tank, including how quickly it heats up, how heat moves around (e.g. stratification), and how quickly it cools down. This would utilise three tank sensors (as described in our previous patent applications ref 1574 or 1590), and a linear model of heat transfer between different segments of the hot water tank.
Applications
Application: Use as Part of a Control System (Automatic Feedback)
[0211] This invention is applicable where the inferred house model is used as part of a predictive control system for managing temperatures in the house. Predictive Temperature Control (as is employed in the methods described in the Huval paper (mentioned above) or PCT Patent Application No. PCT/GB2013/050376) requires a linear model of the form produced by the method described in this document, and uses it to calculate the optimum strategy for heating the system over a future time window. The model to do this can be produced by simpler methods but our approach provides simpler results and greater applicability—for a slow responding heating system with a heat pump or underfloor heating it would be very hard to infer a house model without sophisticated methods such as we have described here.
[0212] The method is fully automatic and invisible to any human operator. The control system starts off using a preset house model, which is updated after measurements come in, and constantly updated (e.g. every night) with new information. The updates are not carried out in situations where the information is questionable: e.g. warm periods, missing sensor data.
[0213] Example: Heat pumps are very hard to control and usually need an installer to choose a “heat slope” which effectively represents the installers belief about the level of house insulation. Our approach to heat pump control eliminates the need for a heat slope as the control algorithms are automatically aware of the thermal dynamics of the house through the learning process, and we estimate that 10% savings in energy consumption are likely to be possible in practice from this approach.
[0214] Example: Weather forecasts. we heat pumps and underfloor systems, houses can respond very slowly to heat input, and so changes in internal temperature or other external conditions such as sunlight can cause significant over or under heating. Learning a model of house the house responds to external conditions (see example above re solar irradiation influence) means that it is possible to control its room temperature a lot better, by receiving a weather forecast from an internet feed for example and adjusting controls accordingly.
[0215] Example: Multi-zone properties, where heat can be channelled to different sets of rooms independently, can be hard to control as temperatures on one room influence another. With a learned model of these connections, we can allow for these influences in advance and ensure for example that a bedroom does not overheat as a result of heating another room previously.
[0216] Example: Hot water, learning a model of a hot water tank, and measuring hot water demand over the course of a day, means that we can optimise production of hot water, for example to not reheat the tank if there will be sufficient left for the evening taking into account cooling and consumption. It also means we can optimise for secondary heat sources such as solar thermal through the use of a weather forecast and knowledge of the impact of irradiation on hot water production via the panels.
Application: Insight (for Manual or Semi-Automatic Feedback)
[0217] The secondary application of this invention is to use the inferred house model to present useful insight to the householder (or other stakeholder such as a landlord). This would mean that they can take actions to improve the physical heating system, the control set-up, or their behaviour in using it. In some cases this feedback is possible semi-automatically, where the system gives the user a suggestion through an interactive interface, to which they have to simply agree to the change rather than go off and implement it independently—this would be possible for example if the control system itself is also doing the learning and communication, and the recommendation is a change in control setting.
[0218] In general, the model provides a quantitative picture of how the house responds to heat input and external conditions, how much energy is required to achieve certain temperature patterns, how quickly the house loses heat, how different parts of the house and heating system exchange heat with each other: insight can be provided in all of these areas.
[0219] We list some specific examples of applications of insight from the house model (in no particular order).
1. Energy consumption/savings prediction. We can use our model to simulate different control strategies and find out the energy impact of a change in the heating schedule, or an override where the householder turned the heating off for a period. This enables quantitative feedback to the customer on the energy consequences of their actions, which will guide them to behave differently in the future. 2. Dynamic feedback on control settings. Similarly to above, we can use a user interface to display the consequences of user choices such as set point and schedule. This could involve a simple graph of predicted room temperature and predicted boiler firing times (so the user can understand what the system is doing and how early a noisy boiler might kick in), as well as predicted energy consumption over the time period. 3. Temperature anomalies. Since we know how the house normally responds to heat input and external conditions, we can identify with confidence events that are unusual. For example, it would be possible to detect sudden cooling caused by windows/doors being left open, or anomalous heating from an oven or log burner. These could be used to prompt the user that they've left the window open, or provide feedback on how much heating oil they have saved by using the log burner (again, using the house model to predict energy consumption in different situations). 4. House characterisation. It would be a valuable service to provide feedback as to the level of insulation a house had, simply by monitoring temperatures. Temperature gradient during a cooling period can indicate insulation levels, as a greater rate of decline indicates more heat loss, but in practice this does not work well because of the influence of thermal inertia—a poorly insulated house with a large thermal mass could have a stable temperature. Our learned house model enables us to distinguish between these two effects. In conjunction with a smart gas meter the method could provide quantitative heat loss estimates. The other hidden states provide insight too: internal thermal mass temperature, external-facing wall temperature, radiator temperature. 1. Fault diagnosis. Similarly to above, we can detect step changes in thermal properties which might indicate a fault with the heating system (such as a seized pump or leaky valve, where boiler firing would not result in as much heat to the rooms as before). Other methods are possible, but the learned house model is superior because we can eliminate the influence of external conditions or brief anomalies. 2. Responsiveness insight. The timescales produced by the house model are interesting in themselves, and would enable presentation to the householder of observations such as how long it takes to heat the house up and whether it's worthwhile turning the heating off when you go out for a short period. This could lead to automatic heating modes such as “keep my house within 20 minutes heating time of 20 C”, and also flagging to the user of short scheduled warm periods where it would take a disproportionate amount of energy to reach set point (as the house would have to be warmer for far longer). This is a case where “semi-automatic” changes could be implemented (changes in heating schedule should not be done fully automatically without the say-so of the householder). 3. Heat pump sizing and choice of “heat slope”. The quantitative understanding in the house model about the relationship between radiator temperature, internal temperature and external temperature is particularly valuable for heat pumps. A monitoring period (using flow/return pipe sensors) prior to installation could help determine what size of heat pump would be necessary and whether radiators needed to be upgraded. It would also be able to specify the right “heat slope” for the house and heating system. 4. Storage heater settings. Learning the properties of a house with storage heaters could enable dynamic advice on controlling it, which is something many people find difficult and is often inefficient. This would require a level of monitoring of charge power (e.g. through current clamps) and ideally charge level (e.g. temperature sensors placed on the storage heater). The user interface would provide a recommendation (in the light of weather forecast as well as the user's prediction of occupancy and set points for tomorrow) of “We suggest you set your storage heater charge level to 3 and tomorrow morning set the discharge at 2.” 5. Multi-zone insight. Along the lines of the automatic example above, we could provide feedback to the user on setting their timers and zone settings, for example “your bedroom receives a lot of heat from downstairs, so we recommend disabling your upstairs zone for morning heating”.
Worked Example
[0231] With reference to FIGS. 5 to 10 we consider a real example of learning the thermal properties of a house with boiler. We have knowledge of the control signals, so the measurements are the room temperature, external temperature (from a weather station), and the boiler firing request from the control system:
[0232] FIG. 5 shows the data captured over a data acquisition period.
[0233] We make an initial guess for the thermal parameters of the house (this is a different house model to that in the maths, with an additional term for the external-facing walls).
r=[0.1 0.1 0.04 2.0 0.18 150 0.04 0.05];
[0235] We can make our first Gibbs step for X given r. FIG. 6 shows a detail of the room temperature trace with the forward-filtered temperature (solid line, higher) and the backward-filtered temperature (dashed line). The latter can be seen to follow the measurements a lot better:
[0236] Note that our state X contains hidden variables. FIG. 7 shows the inferred thermal mass and external wall temperatures:
[0237] and we also infer the radiator temperature, as shown in FIG. 8 :
[0238] These states can provide additional insight about the house and how it responds to heat and how it can best be controlled.
[0239] The next step is to construct the matrix U and vector ρ from the sampled hidden temperature traces and their gradients.
[0240] In this case we calculate U as:
[0000]
3418450
-
1137119
-
123217
0
0
0
0
0
-
1137119
590349
30724
0
0
0
0
0
-
123217
30724
10093
0
0
0
0
0
0
0
0
12306
0
-
192
0
0
0
0
0
0
90838
0
0
0
0
0
0
-
192
0
6
0
0
0
0
0
0
0
0
5313138
-
3276258
0
0
0
0
0
0
-
3276258
3327858
[0000] (displaying numbers rounded) and ρ=[0.0650 0.1030 0.3164 2.5231 0.1874 146.5290 0.0329 0.0539]
[0241] Note the off-diagonal elements of the matrix U, indicating correlations between the parameters—this is an advantage of our approach.
[0242] We have a prior for r as a Gamma distribution with m=[3 3 2 4 2 4 2 2] and θ=[0.0500 0.0500 0.0400 0.6667 0.1800 50.0000 0.0400 0.0500] and using our rejection sampling method we come up with a new value of r as: [0.0662 0.1037 0.3341 2.5037 0.1869 147.7129 0.0307 0.0520]
[0243] This value is fairly similar to ρ—we have a decent amount of data and are not in conflict with the priors—and it is also fairly similar to the initial value of r, but we have taken a small step in the right direction. This is how the Gibbs sampling works, as a Markov Chain Monte Carlo method algorithm for making steps that sample from the right distribution.
[0244] Now we can use this value of r to resample X in turn. FIG. 9 shows a detail of the room temperature graph with forward-filtered and backward-sampled room temperature measurements, using this updated r. We can see that the forward filtered trace is now much closer to the measurements, indicating that the model is better (e.g. It naturally produces the right gradient for the heating period, rather than having to be constantly pulled down by the measurements).
[0245] After the next step
r=[0.0519 0.0816 0.3536 2.5443 0.1867 147.5935 0.0333 0.0552] again slightly updated, and after 30 iterations: r=[0.0603 0.0969 0.6425 2.5737 0.2918 145.6909 0.0618 0.0823]
[0248] We can now use our learned house model to predict the room temperature over this period. The solid line in FIG. 10 shows our predicted room temperature trace solely using (a) the boiler heat request and (b) the external temperature.
[0249] It looks worse than previous traces, but all the previous graphs have used the actual room temperature measurements as an input; here everything about the house's response to heat input and external influences has come from our learned model.
[0250] The spreadsheet at the end of the text of this description sets out the data obtained in the process of another worked example. Since the number of samples k of the data acquisition period is large, certain rows are spread over several pages. The rows in question have been denoted by reference numerals 32-50 to enable the pages to be easily cross-referenced to each other.
[0251] From the present disclosure, many other modifications and variations will be apparent to persons skilled in the art. Such modifications and variations may involve other features which are already known in the art and which may be used instead of or in addition to features already disclosed herein. It should be understood that the scope of the disclosure of the present application includes any and every novel feature or combination of features disclosed herein either explicitly or implicitly and together with any such modification and variation, whether or not relating to the main inventive concepts disclosed herein and whether or not it mitigates any or all of the same technical problems as the main inventive concepts. The applicants hereby give notice that patent claims may be formulated to such features and/or combinations of such features during prosecution of the present application or of any further application derived or claiming priority therefrom.
Proposed Areas of Novelty
[0000]
1. An effective and efficient method for learning the parameters of a model of a heating (or cooling) system given a block of data which may consist of temperature measurements, power measurements, weather information, and control signals.
2. A method as in paragraph 1 where the inference is carried out by Gibbs steps of forward-filtering-backward-sampling and then sampling from a multi-variate gamma-gauss distribution.
3. A method for incorporating a non-linear heating system (e.g. a boiler with a temperature cap or a heat pump) in the method of paragraph 1 by inferring the power it provides to the heat delivery system from the filtered model state.
4. The use of the method to separate the effect of thermal inertia from heat loss.
5. The use of the method to infer the influence of external conditions (such as temperature, solar irradiation etc.) on internal temperatures of the house.
6. The use of the learning process as part of an automated heating controls system, whereby a rolling buffer of data is maintained and periodically used to update the thermal parameters (starting with sensible defaults for the house/heating system type), thereby completing a fully automatic feedback loop.
7. The extension of the method in paragraph 1 and 3 to a storage heater by modifying the thermal model according to discharge vent position and inferring storage heater insulation levels with an additional Gibbs sampling step.
8. The application to controlling heat pumps, underfloor heating, multi-zone properties and hot water.
9. The use of the learned house model to provide insight to a householder, enabling feedback to improve heating management.
10. From paragraph 9, the use of the learned house model to provide predictions about temperature profiles and energy consumption that would result from choices of control settings in order to guide the user.
11. The use of the learned house model to detect in real time anomalies or faults in the house or heating system through behaviour that diverges from that expected from the model.
12. The use of the learned house model to provide quantitative advice on heat pump sizing and the choice of settings such as heat slope.
13. The use of the learned house model to provide timely advice to the user of storage heaters as to what settings they should choose given their future heat requirements.
APPENDIX
Glossary—List of Variables
[0265] We provide a table below of the variables used within this document.
[0000]
Symbol
Description
Example
n r
Number of thermal parameters
6 in the examples above
characterising house model
n m
Number of temperature measurements
Usually 1 (room temperature) but
taken from heating system
may be more (e.g. pipe temperatures)
n s
Number of temperatures characterising the
3 in the examples above
hidden state x of the house
n b
Number of independent energy inputs to
Usually 1, but may be more (e.g.
the house model
hybrid systems)
n f
Number of external influences on the
Usually 1 (external temperature), but
house model
may be more (e.g. solar irradiance
factor)
r
Parameter vector (n r × 1), list of
Usually most components will be
parameters characterising the thermal
numbers in inverse-time units (e.g.
properties of the house. The purpose of
0.1 per hour), thus representing
this invention is to infer r.
timescales, but the r param
measuring energy input will have
different units (e.g. may be degrees
per hour).
y k
Measurement vector (n m × 1) at time
Normally a single number but might
index k (list of temperatures measured
include pipe temperatures, so e.g.
from the home)
vector of two temperatures.
x k
Hidden state vector (n s × 1) at time k, list
Three temperatures: the room
of temperatures characterising the state of
temperature, the temperature of the
the model house.
water in the heating system, and the
temperature of the interior thermal
mass of the house.
A d (r, t)
House evolution matrix (n s × n s ),
See Eqn 2
continuous time. Always a function of r,
may be time t dependent (but usually
constant).
B d (r, t)
Energy input influence matrix (n s × n b ),
See Eqn 2.
continuous time. Always a function of r,
Multiplied by vector of energy inputs
always time t dependent.
E (n_b\times 1)
F d (r, t)
External influence matrix (n s × n f ),
See Eqn 2
continuous time. Always a function of r,
Multiplied by vector of external
always time t dependent.
influences T E (n_b\times 1)
A k (r)
House evolution matrix (n s × n s ), discrete
See Eqn 2 & Eqn 4
time. Always a function of r, may be time
k dependent (but usually constant).
B k (r)
Influence vector (n s × 1), discrete time.
See Eqn 2 & Eqn 4. Implicitly
Always a function of r, alway time k
includes effect of energy inputs and
dependent.
external influence - not known a
priori as exact energy inputs
generally unknown
H
Measurement matrix (n m × n s ), defines
Measuring room temperature from a
y k = Hx k (plus any noise).
three-state model: H = [100]
R
Measurement noise scale matrix
1/σ 2 where σ is the standard
(n s × n s ).
deviation of the measurement noise.
Q
Process noise scale matrix (n m × n m ).
Diagonal matrix where each element
is 1/σ 2 where σ is the standard
deviation of the process noise in
temperature at each step.
T E, k
Measured external influences on the house
Usually just the external temperature,
at time k.
but may also include solar irradiation,
cloud cover, etc.
P k
Measured information about the control
Could be the boiler request signal (0
signals to the house's heating systems at
or 1). In some cases there might be
time k. Usually of size (n b × 1).
multiple control signals that help
inference of a single value of E.
μ k
Inferred mean (n s × 1) of the probability
See x k
distribution of the hidden state x k .
S k
Inferred scale matrix n s × n s (i.e. inverse
of the covariance matrix) of the probability
distribution of the hidden state x k .
E k
Inferred power to the house n b × 1, as
Could be (inferred) actual firing of
would be multiplied by B d to influence the
the boiler (so would be zero when the
house state.
request signal is 1, because the boiler
is maintaining maximum
temperature), i.e. 0 or 1 for gas flame
off or on.
X k
Sampled value of the hidden state vector
As for X k . The difference is that X k
(n s × 1) at time k, list of temperatures
represents a single sampled value
characterising the state of the model house.
after the backwards-sampling step,
rather than a random variable.
D k
Matrix n s × n r representing the linear
See Eqns 8 and 9
relationship between the r parameter
vector and the gradient in the hidden state
vector x.
U
Inferred scale matrix n r × n r (i.e. inverse
See worked example.
of the covariance matrix) of the likelihood
probability distribution of r from the
backward-sampled state vectors over the
time period.
ρ
Inferred mean n r × 1 of the likelihood
See worked example.
probability distribution of r from the
backward-sampled state vectors over the
time period.
m i
Gamma shape parameter for the prior of
2 to 4 (where higher means less
the ith r param (see Eqn 10), where i is 1
confidence in typical scale value).
to n r
θ i
Gamma scale parameter for the prior of the
Typical value (e.g. inverse-time
ith r param (see Eqn 10), where i is 1 to
constant) for that r param.
n r
v
Mode of the posterior distribution of r,
Similar to r.
vector of size n r × 1.
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In a method of apparatus for obtaining thermal property data on thermal properties of a temperature controlled system which includes temperature control apparatus, said data being suitable for use in predicting the temperature of at least part of the system, the following steps are performed: (a) the monitoring the temperature of at least part of the system over a succession of portions or points of a data acquisition period and recording said temperature for each portion or point in an electronic memory; (b) the determining heat transfer data for the period, said heat transfer data being indicative of the amount of heat energy supplied to, or removed from said part over the acquisition period; and determining the thermal property data from the recorded temperatures and heat transfer data, wherein the thermal property data is determined by a process of statistical inference.
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BACKGROUND OF THE INVENTION
This invention is directed to a valve gate assembly for the injection molding of high quality molded articles of various shapes, and more particularly, to an assembly for the molding of molded articles which permits a better filling pattern of the mold cavity to make a substantially stress free part. The present invention also provides an efficiently operating valve gate assembly, especially in combination with a system for guiding molten resin to a molding area.
Copending U.S. patent application Ser. No. 08/690,411 discloses a valve gate injection nozzle including a valve stem means for guiding molten resin to a molding area, the valve stem means including an input area for receiving molten resin, a central area following the input area for processing the molten resin and an output area following the central area for connection of the nozzle with the molding area. The central area includes a first zone for splitting the molten resin into a plurality of streams, a second zone for mixing and homogenizing the molten resin, and a third zone for combining the plurality of streams and forming recombined and substantially homogenized molten resin for subsequent direction to the output area. This apparatus is quite advantageous; however, it is desirable to obtain improvements in the valve gate assembly.
U.S. Pat. No. 5,162,125 shows a large diameter valve gate having an annular filling passage. However, the design of this patent uses springs to close the annular filling passage, and opens by the forward motion of the machine nozzle contacting the sprue and compressing the spring. Thus, the valve head moves forward into the part to allow filling and retracts away from the part to close, leaving a space between the valve head and the part. Although a hole is not cored in the part, the valve head is used to form an annular projection in the part. In the open position, the melt flows through the comparatively wide annular passage. While this is an effective device, it is desirable to develop an improved system.
U.S. Pat. No. 4,368,028 teaches using a core pin to form a hole in a part opposite a fixed "torpedo" in a hot runner nozzle wherein there is a conical projection and a matching conical depression on the core pin and torpedo to cause them to engage and remain aligned during molding. However, there is no teaching of closing the gate opening.
As is known in the art, during injection molding of articles such as PET preforms, unidirectional molecular orientation and weld lines are difficult to avoid using previously developed hot runner valve gated nozzle designs. This defect of these designs presents a major source of concern as such weld lines and unidirectional orientation are potential causes for the weakness of a blown PET bottle that may subsequently be filled with a carbonated beverage under pressure, thereby increasing the risk of a container rupture. In addition, weld lines may also reduce the strength or have an adverse effect on the dimensional accuracy of injection molded precision parts such as gears, which have a central hole, especially those used for high load applications. Also, for articles used in optical applications, such as the compact disc (CD) and digital video disc (DVD), weld lines and unidirectional molecular orientation induce birefringence, which is an unacceptable defect given the fact that information carried by pits embedded in the surfaces of these discs has to be retrieved by passing a laser beam through the plastic substrate from which they are formed, from a side located opposite the pits. Injection molding of CDS and DVDs is even more challenging, considering that both of these molded articles must have a precisely located central hole. Ideally, CDS and DVDs should be molded using a sprueless injection process in order to save plastic resin, reduce the cycle time and simplify the design of the mold and the injection molding machine. The former developments in the art, however, fail to teach such a system and more particularly, fail to teach a hot runner valve gate nozzle and mold, and method which are capable of spruelessly producing CD's and DVD's with an acceptable birefringence level and within tight geometrical tolerances.
Prior developments in the molding art discuss various method for producing plastic articles which do not present weld lines or unidirectional molecular orientation. However, these method do not provide satisfactory results with regard to using hot runner manifolds and nozzles.
Some of the more pertinent developments in the art are discussed as follows.
With the intent to reduce the contact between the movable stem and molten resin so as to prevent the appearance of weld lines caused by splitting of the molten resin around a valve stem, U.S. Pat. No. 4,412,807 to York discloses a valve stem located parallel to the flow of the molten resin. The valve stem therein has very limited contact with the resin which is very close to the nozzle tip. While weld lines are reduced using this design, a substantial core shift is introduced because the flow of the resin is not symmetrical with respect to the cavity gate and there is a tendency for the resin to preferentially fill one side of the cavity faster then the other.
Similar to York, U.S. Pat. No. 4,925,384 to Manner discloses a hot runner valve gate which also includes a valve stem positioned parallel to the flow of the molten resin. However, this stem is only in partial contact with the molten resin along the inner melt channel of the hot runner nozzle. The melt does not fully surround the stem, thus giving a slight improvement with respect to the appearance of weld lines. However, since the melt channel is again laterally shifted with respect to the cavity gate, some weld lines and core shift still appear. In addition, guiding the stem only by the upper portion thereof represents another drawback of this system.
Further, U.S. Pat. No. 5,104,307 to Brink teaches a valve gate stem that makes an angle with respect to the flow of the molten resin and acts upon a ball shaped closing pin. By using this design, there is no contact between the stem and the resin. However, this design clearly increases the size of the hot runner nozzle, is very difficult to seal with respect to leakage around the ball shaped pin, and cannot be used in many applications such as in cases where molded articles are to be formed having a precisely located central hole.
Another approach to improve the quality of plastic articles and to prevent the formation of weld lines has been to use non-valve gated hot runner nozzles, as disclosed in U.S. Pat. No. 4,965,028 to Maus et al. An extended reference list to patents directed to this type of approach is also discussed in this patent. Maus et al. discloses and claims a melt conditioning elements comprising heating, filtering and mixing features located just upstream of the molded gate. These features are proposed to improve the quality of the melt and accordingly, the quality of the plastic article to be molded. This mixing feature as disclosed and Maus et al. is not entirely new to that disclosure and reference is accordingly made to German Patent Application DE3201710 A1 of Gellert.
Gellert teaches a generic twisted strip located in the nozzle which is used to produce turbulence and to reduce uniaxial properties in the molded articles. The mixing element of Gellert is not very effective since it does not split and remix the molten resin flow aggressively enough to prevent the formation of weld lines, which are caused by the splitting and twisting of the incoming stream of molten resin into multiple streams that reach the cavity. The melt conditioning element of Maus et al. is, however, more effective as a mixer but causes a relatively high and nondesirable pressure drop that increases the cycle time of the injection molding machine. For both of the hot runners disclosed in Maus et al. and Gellert, valve gate stems are not used and accordingly, these devices have a substantially limited range of application.
Still another approach for avoiding the unidirectional molecular orientation of melt is shown in several patents which teach different manners for inducing helical movement to the molten resin around the stem of a hot runner valve gate. Accordingly, reference is made to U.S. Pat. No. 4,303,382 of Gellert that teaches three helical channels located in the inner wall of the nozzle that surrounds a valve stem. These channels end up just prior to the tip of the nozzle and are used to impose a curving motion to the melt when it enters the mold cavity. While this design will avoid unidirectional molecular orientation of the molten resin, it will not prevent the formation of weld lines since the three streams of molten resin are not mixed together before entering the cavity.
Other molding applications require the inducement of circular or helical movement of the molten resin where the molten resin must have a very limited amount of contact with the stem of the valve gate. Such applications include the simultaneous coinjection of several molten resins to a common gate. For example, reference is made to U.S. Pat. No. 4,512,730 of Kudert and U.S. Pat. No. 5,143,733 of Von Buren. Kudert teaches a complex hot runner nozzle design concept wherein the annular flow profile of each molten resin that arrives in the hot runner nozzle is transformed into a circular or helical profile that is totally separated from the valve gate stem. By inducing concentric movements of each individual resin for their simultaneous injection, the combined stream entering the cavity mold would fully surround each nozzle and accordingly, the layers of the streams fill the entire cavity. Von Buren teaches a different valve gate hot runner nozzle for coinjecting three resins through a single mold gate, wherein only one of the resins follows a quasi circular flow. With reference to FIG. 3, channel (104) has a helical profile that allows one thin stream of resin to fully surround nozzle body (83) for causing the same to reach the gate as a complete symmetrical molten resin stream. Neither Kudert nor Von Buren teach a valve gate hot runner that is capable of effectively mixing and homogenizing a single stream of molten resin so as to prevent the formation of weld lines in the final molded product.
With reference to U.S. Pat. No. 4,340,353 to Mayer, U.S. Pat. No. 5,324,190 to Frei and U.S. Pat. No. 5,460,763 to Asai, several sprueless injection molding methods for manufacturing compact discs having an accurate central hole are disclosed. However, no provision is made to avoid the appearance of weld lines or to avoid unidirectional molecular orientation of the melt. Specifically, Mayer teaches a plurality of radially outwardly and angularly spaced extending arms (76) and (78) used to guide a valve stem (74) along two sections. These arms, together with flow opening (89) represent obstructions of the incoming flow of molten resin, toward the mold cavity, which generate several melt lines that are visible using polarized light. Less visible weld lines are expected to be generated using the design taught in Frei and Asai since they do not have these kind of guiding arms disturbing the flow of the resin. However, neither patent teaches any means to recombine the individual streams of molten resin after they are split and prior to entering the cavity gate, so as to provide a viable solution for avoiding the appearance of weld lines. All three of these patents teach different methods and means to form a central hole in a time efficient and simple manner without discussing the high potential in each for injecting compact discs that have weld lines and unidirectional molecular orientation in the solidified resin.
The difficulty which arrives in removing weld lines caused by the interruption or splitting of the flow of plastic material is emphasized in U.S. Pat. No. 4,942,010. In this patent, a simple but very limited mixing solution for reducing weld lines is disclosed. Further disclosure which indicates the difficulty in eliminating weld lines is found in U.S. Pat. No. 4,584,154 discussing that polycarbonate, a material frequently used in molding CDS, is very sensitive to the formation of weld lines caused by the first splitting and then reuniting of separate streams.
There exists a need, therefore, for an apparatus for use in sprueless injection molding operations for molding high quality molded parts, and particularly, high quality molded parts having a precisely located central hole, wherein the molded part is substantially free of solidified resin having unidirectional molecular orientation and which is also free of weld lines. There is a particular need for such an apparatus with an efficiently operating valve gate assembly.
SUMMARY OF THE INVENTION
The primary object of this invention is to provide an improved apparatus for the sprueless injection molding of high quality plastic articles.
Another object of this invention is to provide an apparatus that permits a better filling pattern of the mold cavity to make a substantially stress free part.
Yet another object of this invention is to provide an apparatus for the injection molding of high quality plastic articles using an efficient and expeditious valve gate assembly.
Further objects and advantages of the present invention will appear hereinbelow.
The foregoing objects and advantages are obtained in accordance with the process and valve gate assembly of the present invention. The valve gate assembly comprises: a movable valve stem for guiding molten resin to a molding area; a nozzle body portion enclosing said valve stem; channel means for molten plastic enclosed by said nozzle body; a mold cavity for receiving molten plastic to form a molded part formed between cooperating first and second mold halves; an injection orifice downstream of the valve stem communicating with said mold cavity and channel means for transportation of molten plastic from the channel means to the mold cavity; and a movable core pin contacting said valve stem and movable between a forward position opening said injection orifice and a rearward position closing said injection orifice.
The valve stem is situated in the first mold half, and the core pin is situated in the second mold half. The valve stem is movable from a forward position blocking said injection orifice to a rearward position opening the injection orifice. The core pin is operative to move the valve stem from a forward position to a rearward position.
The valve gate assembly of the present invention is particularly advantageous when the valve stem includes an input area for receiving the molten resin, a central area following the input area for processing the molten resin and an output area following the central area for connection of the nozzle with the molding area. The central area includes a first zone for splitting the molten resin into a plurality of streams, a second zone for mixing and homogenizing the molten resin, and a third zone for combining the plurality of streams and forming recombined molten resin for subsequent direction in a homogenized state to the output area. The nozzle further includes a nozzle body portion for enclosing the valve stem, wherein the nozzle body portion includes means for heating the resin.
The details of the present invention are set out in the following description and drawings wherein like reference characters depict like elements.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a valve gate nozzle according to the principles of the present invention for use with an injection molding machine and an associated nozzle for making molded articles having a precisely located central hole, such as compact and digital video discs;
FIG. 1A is a cross-sectional view of one embodiment of the entrance opening arrangement of the valve stem shown in FIG. 1;
FIG. 1B is a cross-sectional view of another embodiment of the entrance opening arrangement for the valve stem shown in FIG. 1;
FIG. 2 is a cross-sectional view of another embodiment of a valve gate nozzle in accordance with the principles of the present invention for use in conjunction with an injection molding machine for making molded articles which are free of weld lines and/or unidirectional molecular orientation;
FIG. 3 is an elevated and partially cross-sectional view of a valve gate stem in accordance with the principles of the present invention;
FIG. 4 is an elevational and cross-sectional of another embodiment of a valve gate stem in accordance with the principles of the present invention;
FIGS. 5A-5D illustrate the method steps for forming a high quality molded article, such as a compact or digital video disc, in accordance with the principles of the present invention using the hot runner valve gated nozzle shown in FIG. 1;
FIG. 5E is an enlarged sectional view of the open gate for allowing molten resin to be injected into a mold cavity for forming a precision molded article such as a compact or digital video disc, in accordance with the method illustrated in FIG. 5A-5D;
FIGS. 6A and 6B illustrate a method for molding precision gears in a single cavity mold using a hot runner valve gated nozzle as shown in FIG. 1, in accordance with the principles of the present invention;
FIG. 7 is a partially cross-sectional view of a multi-cavity mold and hot runner manifold comprising a hot runner valve gate in accordance with the principles of the present invention, and which includes a valve gate stem and a mechanism for actuating the valve gate stem;
FIG. 7A is a cross-sectional view of one embodiment of the entrance opening arrangement of the valve stem shown in FIG. 7, similar to that shown for FIG. 1A;
FIG. 7B is a cross-sectional view of another embodiment of the entrance opening arrangement for the valve stem shown in FIG. 7, similar to that shown for FIG. 1B;
FIG. 8 shows the mold closed and the valve gate assembly of the present invention in the open position for injection;
FIG. 9 is similar to FIG. 8 and shows the mold open and the valve closed; and
FIG. 10 shows a split view of the details of the valve gate assembly of the present invention, with the left half showing the valve open and the right half showing the valve closed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in detail, there is shown in FIG. 1 a cross-sectional view of a hot runner valve gate, designated generally as 10, as it works actuated and in conjunction with machine nozzle 11 of an injection molding machine (not shown), in accordance with the principles of the present invention. In general, hot runner valve gate 10 comprises injection nozzle 13 and includes a valve gate stem 12 located in an elongated cylindrically shaped nozzle body 14, wherein nozzle body 14 is made of a heat conductive material and is surrounded by lower heating elements 16 and upper heating elements 18, which are used to maintain the molten resin at the optimal temperature required by the injection molding process.
Valve gate stem 12 includes an inner melt conduit 20 which allows for the free access of the injected molten resin inside the nozzle body 14. As is further shown generally in FIG. 1, upper heating elements 18 are surrounding by a spring 22 which is used to maintain a tightly sealed contact between the entrance end 24 of valve gate stem 12 and a molten resin sequential feeding device, such as injection molding machine nozzle 11, for feeding resin into inner melt conduit 20. During the injection molding process, valve gate stem 12 is axially displaced within nozzle body 14 so as to allow the flow and shut off the flow of molten resin into the cavity mold 42.
Valve gate stem 12 in accordance with the principles of the present invention includes a plurality of innovative design features which contribute to the substantial elimination of weld lines and/or of unidirectional molecular orientation of the molten resin used to form a molded plastic article. Referring to FIG. 2, valve stem 12 is shown as including a plurality of functional axial zones which are used to substantially accomplish the elimination of weld lines and/or the disruption of unidirectional molecular orientation of the resin therein, in the final molded product. In accordance with the following description, the plurality of functional zones uniquely function together in creating a stream splitting, three-dimensional mixing and recombination technique for substantially homogenizing molten resin flowing adjacently thereto. These zones include radial splitting zone R, first mixing zone M1, second mixing zone M2, straight zone S, and flow cut-off zone O.
Accordingly, and also referring to FIG. 2, molten resin enters under pressure inner melt conduit 20 and travels substantially undisturbed over a distance L until it reaches a radial melt splitter 26 in a first radial splitting zone R. Melt splitter 26 has been specially designed to provide substantially no pressure drop of the molten resin downstream of melt conduit 20 and thus to maintain a high molding cycle time. In one preferred embodiment, melt splitter 26 comprises a plurality, and in this embodiment, preferably three annular melt conduits 28, 30 and 32, defined initially by entrance openings 33, as shown in FIGS. 1A and 1B. These conduits 28, 30 and 32 are angularly spaced in valve stem 12. All three conduits 28, 30 and 32 of radial melt splitter 26 are in direct fluid communication with outer surface 34 of valve gate stem 12.
As shown in FIG. 1A, the molten resin may be split into at least two, and preferably three or more individual streams using radially spaced orifices or entrance openings 33 that are made exterior to the stem, i.e. between the stem 12 and the nozzle body 14. Alternatively, as shown in FIG. 1B, the streams of molten resin may be led fully into the stem before directing them outside towards the helical channels. That is, the entrance openings 33 in FIG. 1A are fully formed within the body of the stem and are not formed in part by nozzle body 14.
Accordingly, incoming molten resin which reaches radial melt splitter 26 as one tubular flow stream, and which carries the heat history of the entire travel of the streams through the manifold and nozzle of the injection molding machine, is divided by radial melt splitter 26 into a plurality of equal streams, and preferably three streams in accordance with conduits 28, 30 and 32 with substantially no pressure drop to the molten resin. Accordingly, three streams of molten resin simultaneously reach outer surface 34 at the beginning of the first mixing zone M1 of valve gate stem 12. Since no pressure loss occurs, each stream of molten resin is forced by the pressure to enter one of helical inner channels 36, which are precisely formed in outer surface 34 of valve gate stem 12 along first mixing zone M1, as shown in FIGS. 1 and 2. Mixing zone M1 of valve gate stem 12 is tapered starting from the upper end of area T and down to the upper end of second mixing zone M2. The taper of area T continues through second mixing zone M2, to straight zone S. Due to the tapering of valve gate 12 in mixing zone M1 starting in tapered area T, over a portion of the axial length of helical channels 36, a certain amount of molten resin from each stream undergoing a helical travel in mixing zone M1 is injected over barrier flights 38 separating the helical channels. Accordingly, a three-dimensional mixing process occurs. That is, in addition to the helical displacement of the molten resin along the three different helical channels, the movement of the molten resin over barrier flights 38 creates a mixing process for portions of the individual streams injected over the barrier flights, while the remaining portions of the individual streams continues its helical path. Eventually, in zone M2 and tapered area T1, which is a smoothly tapered area without the helical channels, a single homogenized stream of molten resin is formed, having circular flow which fully surrounds the outer surface of valve gate stem 12. In this manner, molten resin as a singular circular flow stream resides for a short period of time between nozzle body 14 and valve gate stem 12 at lower tapered area T1 as a single homogenized molten stream that substantially does not include any resin having unidirectional molecular orientation.
As shown in FIGS. 1 and 2, tapered area T ends with an outwardly extending dam 40 which functions to partially obstruct and as a result thereof, partially send backward the homogenized molten resin into tapered area T, prior to the entrance of the homogenized molten resin into the straight zone S of valve gate stem 12. In this manner, further mixing of the molten resin is achieved so as to further assure the elimination of unidirectional molecular orientation. Accordingly, in straight zone S a single stream of highly homogenized molten resin surrounds valve gate stem 12 and is now properly prepared and directed for injection into mold cavity 54, shown schematically in FIG. 1. In this respect, the highly homogenized molten resin residing for a short period of time in straight zone S does not have unidirectional molecular orientation and when injected into mold cavity 54, does not exhibit any weld lines that usually appear using formerly developed hot runners and their respective valve gates.
A final cut-off zone O is also provided, as shown in FIG. 2 (and more clearly in FIG. 5E), for shutting off the gate and the flow of molten resin to mold cavity 54. Accordingly, zone O preferably comprises a circular surface having a diameter for nearly engaging the inner diameter of nozzle housing 14, for cutting off the flow of molten resin through nozzle housing 14, adjacent valve gate stem 12 into the mold cavity 54. Therefore, upon the upward actuation of valve stem 12 into nozzle housing 14, as described below with reference to FIGS. 5A-5D, cut-off zone O substantially engages the inner diameter of housing 14 for cutting off molten resin flow.
As shown in FIG. 1, valve gate injection nozzle 13 also includes a tip 44. Tip 44 is used in molding situations wherein the injection nozzle 13 is to be used to make molded articles requiring a precisely positioned central hole, such as in the production of compact and digital video discs and precision gears, which also require and/or are preferably formed from molten resin having homogeneous molecular orientation. Accordingly, the gate injection nozzle 13 shown in FIG. 1 is very suitable for injecting polycarbonates and excellent results have been obtained for such applications, providing the sprueless injection molding of compact and digital audio discs having no weld lines caused by a stream splitting.
Referring now to FIG. 3, a hot runner valve gate 110, valve stem 112, nozzle body 114, cavity mold 142 and valve gate injection nozzle 113 are shown which have a design very similiar to that shown in FIG. 1. The primary and substantially only difference between valve gate injection nozzle 113 and valve gate injection nozzle 13 is the lack of tip 44 and the substitution therefor of a further tapered area TT after straight zone S instead of tip 44. Accordingly, tapered zone TT forms tip 146 which allows for the flow of molten resin from straight zone S in the very homogenized state to mold cavity 154 without the formation of a precisely aligned central hole.
Referring now to FIG. 4, a valve gate injection nozzle 213 and nozzle body 214 are shown which are similar to the embodiment shown in FIGS. 1 and 3 and is preferably used for injecting plastic materials that are less sensitive to the inducement therein of unidirectional molecular orientation during the injection molding process. Accordingly, this nozzle could be used to eliminate such unidirectional molecular orientation and associated weld lines when materials that are less sensitive to these undesirable features, are used. The primary difference between valve gate stem 212 and valve gate stems 12 and 112, discussed above, is that valve gate stem 212 does not include the tapered zones and the dam on the outer surface thereof. That is, after mixing zone M including helical channels 236, a straight zone S immediately follows, as shown in FIG. 4. Preferably, however, the helical path of helical channels 236 has a more aggressive geometry that improves mixing in the mixing zone M and cylindrical zone S between nozzle body 214 and valve stem 212. Accordingly the helical turns of channels 236, these turns are more severe and the helical path more compact, as shown. Referring now to FIGS. 5A-5D, a method for precise and molecularly homogeneous injection molding of compact and digital video discs is shown, using the valve gate injection nozzle as discussed above with reference to FIGS. 1 and 2. In accordance with the following method, an innovative mixing and homogenizing means is shown that contributes to the success of injection molding compact and digital video discs which lack weld lines and unidirectional molecular orientation, in reproducible cycle times.
Referring now FIG. 5A, to begin injection molding, the injection mold comprising core side 50 and cavity mold 42 are moved to a closed position prior to the injection step. Also, the machine nozzle 11 is in sealed contact with valve stem 12 at entrance end 24, which contact is permanently maintained by compression spring 22 during the entire molding cycle time. An injection unit (not shown) is equipped with double acting stroke cylinders, while a hydraulic cylinder 52 is double action. Accordingly, when the front chamber (not shown) of the injection unit stroke cylinder is pressurized, the injection unit including nozzle 13 is forced to retract. The rear chamber of the injection unit is pressurized with hydraulic pressure which causes the injection unit and nozzle 13 to move forward along distance K so as to open the mold gate via the advancement of valve gate stem 12 and tip portion 44 into cavity mold 42, as shown in FIG. 5B. In this position no contact is achieved until piston 52 is pushed forward by pressure, as shown in FIG. 5E. Also, valve gate stem 12 and hydraulic actuator 56 are in sealed contact caused by the mechanical pressure generated between these elements, which prevents leakage of molten resin. As shown in the enlarged cross sectional view of the mold gate in the open position, FIG. 5E, molten resin is allowed to fill mold cavity 54 under pressure from the machine nozzle which forces the molten resin in a helical movement through mixing zone M of stem 12. In order to reduce heat coming from stem 12, cooling fluid F is brought via cooling conduit 58 and circulated within hollowed core 60 of hydraulic actuator 56. FIG. 5C represents the next step wherein machine nozzle 11, shown best in FIG. 1, is retracted and opposed fluid pressure is applied to hydraulic cylinder 52, in port A, in order to advance hydraulic actuator 56 in a follow-up movement together with the back retraction of stem 12 which is pushed by spring force. The controlled advancement of actuator 56 through mold cavity 54 is intended to create a smooth and accurate sprueless central hole in the injection molding disc that remains in the mold for final cooling before being ejected using an ejection mechanism. The final step is shown in FIG. 5D, wherein when the mold opens and cylinder 52 retracts, disc 62 is released.
Referring now to FIGS. 6A and 6B, a method similar to that as discussed for FIGS. 5A-5E, using actuator 56 (which may be hydraulic, spring actuated, or pneumatic, or any other desirable means), can be used to inject a different type of resin for forming a precision gear 66, which has a precisely located central hole. While birefringence is not an issue for this type of application, both avoiding weld lines and coring of the central hole can be advantageously achieved using the same apparatus described with respect to FIGS. 1 and 2 and FIGS. 5A-5E, for making compact and digital video discs.
Referring now to FIGS. 7, 7A, and 7B, valve gate injection nozzle 313, nozzle body 314 and melt conduit 320, similar to as discussed above with reference to FIG. 3, is shown in use with a multi-cavity mold and a hot runner manifold used to produce high quality PET preforms for forming thin walled containers, wherein the avoidance of weld lines and unidirectional molecular orientation is desired but a central hole is not. In this embodiment, the actuation of valve gate stem 312 is done by hydraulic or air pistons 370 independent of the injection molding machine, representing a difference between this embodiment and the previous embodiments as discussed above. Other wise, the operation of the FIG. 7 embodiment is similar to as that discussed above for FIGS. 5A-5E and similar numerals designate similar elements. FIGS. 7A and 7B, similar to FIGS. 1A and 1B, are representative of the various arrangements of entrance holes 333. For a detailed description of the nozzle and related elements, as shown in FIG. 7, reference is made to U.S. Pat. No. 4,173,448 to Rees et al., assigned to the assignee of the present invention, which is hereby incorporated in total by reference. However, instead of rod 29 shown therein, valve stem 312 of the present invention, as described in detail above with further reference to valve stems 12 and 112, is used. Valve stem 312 includes an extended shut-off zone O' which is a part of the straight zone S', for functioning with the system shown in Rees et al, for cutting off flow of recombined molten resin to the mold cavity.
The primary advantage of the foregoing is that an improved apparatus and method is provided for the sprueless injection molding of high quality plastic articles. Another advantage of the foregoing is that an apparatus and method is provided for the sprueless injection molding of high quality plastic articles, wherein the articles have various shapes, are made from various resins, and do not have weld lines. Yet another advantage of the foregoing is that an apparatus and method is provided for the sprueless injection molding of high quality plastic articles which do not have a unidirectional molecular orientation and/or weld lines. Still another advantage of the foregoing is that an apparatus and method is provided for the sprueless injection molding of high quality plastic articles having a precisely positioned central hole and which do not have unidirectional molecular orientation and weld lines. And yet another advantage of the foregoing is that an improved apparatus and method is provided for homogenizing molten plastic resin in the immediate vicinity of a mold gate prior to injection into the mold. Still another advantage of the foregoing is that a hot runner manifold is provided which comprises an improved hot runner valve gate for homogenizing molten plastic resin in the immediate vicinity of a mold gate. And still another advantage of the foregoing is that an improved injection nozzle is provided for use with an injection molding machine for molding articles with homogenized molten plastic resin for forming molded articles without weld lines and solidified resin having unidirectional molecular orientation.
The improved valve gate assembly of the present invention is shown in FIGS. 8, 9 and 10. With reference to FIG. 8, which shows the mold closed and the valve in the open position for injection, the features of the valve gate assembly can be clearly seen. Valve stem 12 includes valve head 68 as a forward or downstream portion of the valve stem assembled to the valve stem by thread 70 (see FIG. 10) tightened by means of tool recess 72. The nozzle body 14 includes a recessed annular passage 74 which in combination with the annular shape 76 on the valve stem-valve head combination forms an annular channel 78 where melt accumulates prior to injection. Upstream annular projection 80 on valve stem 12 acts as a dam to modify the melt flow which has passed through mixing unit 82, described above in connection with FIGS. 1-7 inclusive.
The left half of FIG. 10 shows the valve in the open position such that the melt can pass through annular gap 84, formed between nozzle body land 86 and core pin 88 and flow into mold cavity 54. The valve is opened by the forward motion of core pin 88 which pushes on valve head 68 and compresses spring 22. Note that the valve stem is located in one mold half and the core pin is located in the other mold half. The forward stroke of the core pin is shown by dimension "D" in FIGS. 8 and 10 and is limited by the stroke of the cylinder in the core half of the mold (not shown). After mold cavity 54 has been filled and the hold portion of the cycle is completed, the core pin 88 is retracted to close the valve as shown in the right half of FIG. 10. The forward position of the valve is stopped by shoulder 90 clearly shown in FIGS. 8 and 9. After completion of the cooling cycle and during mold opening, core pin 88 is retracted into the core half of the mold as clearly shown in FIG. 9 to clear hole 92 which has been formed in molded part 94.
The foregoing valve gate assembly has proved to create improved flow conditions for filling the part, especially in combination with the mixing unit shown in FIGS. 1-7, producing a weld free and stress free molding. In addition, the gate and core pin combination form a clean, flash free hole with substantially parallel sides.
The annular gate passage 86 is desirably narrow and parallel for a finite length. This creates a local heating effect for the resin as it flows through this restriction and permits a better filling pattern of the mold cavity to make a substantially stress free part. Moreover, the opening of the valve gate is obtained by moving the valve head 68 away from the mold cavity and back into the heated nozzle 14 area so that the head picks up some heat from the melt flowing around it during filling. This functions to counter the cooling effect of the core pin 88 during filling. The core pin 88 is in the cooled core half of the mold and acts like a heat sink while in contact with valve head 68. In addition, desirably the core pin itself forms part of the annular passage for filling in addition to coring the hole in the part. Thus, in accordance with the valve gate assembly of the present invention, the core pin functions to open/close the valve in the opposite mold half. The valve gate assembly of the present invention uses part of the core pin to form part of the gate geometry, and the specific annular shapes of the gate area groove 74 and land 86 form an annular inlet to the mold cavity.
It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.
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A valve gate assembly including a movable valve stem for guiding molten resin to a molding area, a nozzle body portion enclosing the valve stem and a mold cavity for receiving molten plastic to form a molded part formed between cooperating first and second mold halves. An injection orifice is provided downstream of the valve stem communicating with the mold cavity for transfer of the molten plastic to the mold cavity, and a movable core pin is provided contacting the valve stem and movable between a forward position opening the injection orifice and a rearward position closing the injection orifice.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This is a Continuation of U.S. application Ser. No. 10/536,615, filed May 26, 2005, which is the National Stage of International Application No. PCT/AU03/01596, filed Dec. 1, 2003, which claims the benefit of Australian Application Serial No. AU 2002953027, filed Nov. 29, 2002; and is a Continuation-in-Part of U.S. application Ser. No. 10/276,547, filed Nov. 14, 2002 and now U.S. Pat. No. 6,964,183, which is the National Stage of International Application No. PCT/AU01/00579, filed May 18, 2001, which claims the benefit of Australian Application No. PQ7576, filed May 18, 2000.
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a dual lock apparatus, and in particular, to a dual lock apparatus that has at least two independent means of acting on a lock whereby operation of the two locking means is controlled by an improved clutch mechanism.
2. Background Information
In a previous patent by the same applicant (PCT/AU01/00579 entitled ‘A Dual Lock Apparatus’), whose contents are expressly incorporated by reference herein, there was disclosed a locking apparatus having at least two independent means of acting on a lock. Although the apparatus as described in the aforementioned patent has been found to function satisfactorily, an improved clutch mechanism which allows the two locking mechanisms to function independently has been developed and is the subject of the present application.
There are numerous types of locks in existence today that are used to secure various devices. One of the more common uses of locks is in relation to doors. Typically door locks have a bolt that can be extended from a locking mechanism so as to engage a doorframe or furniture with the bolts being driven by the use of a unique or slave key. There have also been developed locks that are not only operable by the use of the slave key but also a master key, allowing the master key holder, for example, to operate all doors in a pre-defined area whilst the slave key holders are limited to being able to operate specific doors only. This however requires the master key and the slave key to be of the same type thus potentially compromising security.
There have also been developed electromechanical locks that use an electric motor to drive the bolt. The difficulty with these types of arrangements is that if the electric motor was for whatever reason inoperable, the door may be left either in the unlocked or locked state and may require disassembly to be fixed.
Further still, the difficulty with some existing locks is that although the door may be unlocked, that is it may be opened, the bolt still engages a portion of the door frame and further manual operation of the bolt by the use of a handle is required to be able to open the door. On the other hand, if the bolt was to be retracted fully, then the door may swing freely, also an undesirable effect.
It is an object of the present invention to propose a locking apparatus that overcomes at least some of the abovementioned problems or provides the public with a useful alternative.
Although the present specification discusses doors in particular it is to be understood that the present invention is not intended to be limited to doors and may equally well be used to provide a locking apparatus in relation to other devices such as safes and gates to name but two.
SUMMARY OF THE INVENTION
In one form of the invention there is proposed a dual lock apparatus of the type including a lock moveable between a first position whereby said lock extends outwardly from said apparatus and a second position whereby said lock is contained within said apparatus said apparatus including:
a slider movable between a first position and a second position and including a first end associated with said lock such that movement of the slider causes corresponding movement of the lock, and a second end associated with a first locking means and a second locking means whereby independent operation of said first and second locking means is controlled by a clutch mechanism;
said clutch mechanism including an aperture which extends through said slider and a piston movable between at least a first and second position within said slider aperture;
said second locking means including a member movable between a first and a second position said member including an outwardly biased locking member adapted to engage said slider aperture to thereby mechanically connect said second locking means with said slider to thereby effect movement of said slider upon movement of said member;
said first locking means including a rotatable cam such that when rotated said cam acts against said piston to thereby move said piston from said first position to said second position to thereby mechanically connect said first locking means with said slider to thereby effect movement of said slider.
Preferably said first locking means disengages said second locking means.
This allows independent operation of said first locking means with respect to said second locking means.
The above provides the advantage that if the second locking means is one that may be exposed to potential failure, the first locking means ensures that there is a safeguard in that the lock can always be operated even if the secondary locking means has ceased to function.
Advantageously at least one of said locking means is electrically driven. Advantageously said first locking means is a key activated locking means whilst said second locking means is an electromechanical locking means.
Preferably both said first and second locking means are key activated.
A particularly apt use of this invention is in the case where the electromechanical locking means is controlled by remote activation of an electric motor. If for whatever reason the electric motor were to fail, such as a power failure, then the primary locking mechanism that is operated for example by a key may be used to unlock or lock the lock.
Advantageously when said slider interacts with said locking bolt so as to move it into said first position, said slider resists withdrawal of said locking bolt.
In a further form of the invention there is proposed a dual lock apparatus of the type including a locking bolt moveable between a first position extending outwardly from said apparatus to engage with an external restraining means and a second position to be contained within said casing said apparatus including:
a slider adapted to interact with said locking bolt so as to move it into said first or second position said slider including at one end an aperture extending perpendicularly to the direction of motion of said slider said aperture adapted to house a slider abutment member;
said slider abutment member being moveable between a first position whereby a surface of said member is flush with a surface of said slider and a second position whereby said surface of said member is housed within said aperture;
a carriage associated with said slider said carriage including an abutment surface said carriage further being moveable between a first position wherein said slider is located in said slider second position, and a second position thereby urging said slider into said slider first position;
a first locking means having a rotatable cam means such that when rotated in a first direction so as to act against said carriage abutment surface urges said carriage into said carriage second position and said abutment member into said first position to thereby urge the slider towards its first position and thereby outwardly extend said bolt and when said cam is rotated in an opposite direction it acts to thereby urge the slider towards its second position to thereby inwardly retract said bolt;
a second locking means adapted to be activated independent of said first locking means including a rack associated with said slider and movable between a first position whereby said bolt is inwardly retracted and a second position whereby said bolt is outwardly extended, said member including an outwardly biased pin housed within a rack cavity and movable between a first and a second position, in said first position said pin engaging with said slider aperture to thereby effectively mechanically couple said second locking means to said slider and thus the bolt and in said second position said pin forced into said cavity whereby said slider may freely move to thereby effectively decouple said second locking means from the slider, this occurring when said slider abutment member is in said member first position.
Preferably when said cam discontinues urging of said carriage, a biasing member acts upon said pin to return it to said first position upon alignment of said pin and said slider aperture.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations or embodiments of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings,
FIG. 1 is a top view of the internal components of a lock in an unlocked configuration and including the lock slider body of the present invention;
FIG. 2 is a top view of the internal components of the lock of FIG. 1 in a locked configuration using a secondary locking mechanism, more specifically, an electric motor and rack system;
FIG. 3 is an exploded perspective view of the different components of the lock of FIG. 1 ;
FIG. 4 is an alternate exploded perspective view of the different components of the lock of FIG. 1 ;
FIG. 5 is a cross-sectional view of the main component of the lock of FIG. 1 whereby the secondary locking mechanism is used to lock the bolt;
FIG. 6 is a cross-sectional view of the main component of the lock of FIG. 1 whereby a primary locking mechanism (a key operated cam) disengages the secondary locking mechanism;
FIG. 7 is a cross-sectional view of the lock as in FIG. 6 whereby the primary locking mechanism is used to lock the bolt subsequent to disengagement of the secondary locking mechanism;
FIG. 8 is a cross-sectional view of the main components of the lock of FIG. 1 whereby the lock is in its fully locked state using the primary locking mechanism; and
FIG. 9 is a cross-sectional view of the main components of the lock of FIG. 1 whereby the lock is in its fully unlocked state using the primary locking mechanism.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts.
The present invention relates to locks and in particular to locks that are used for hollow winged aluminium doors and the like. It may also be adapted to be used on other type of doors such as sliding doors. It is not intended to limit the invention to any particular type of lock or door.
Shown in FIGS. 1 and 2 is a dual lock 10 in accordance with the present invention, FIG. 1 illustrating the lock 10 in its unlocked state and FIG. 2 showing the lock 10 in its locked state. FIGS. 1 and 2 illustrate the use of a secondary locking mechanism, generally indicated at 99 , that is, the use of an electric motor 100 to lock or unlock the lock 10 and which will be described hereinbelow. The primary locking mechanism, which is slightly more complex, will also be described.
A casing 12 is adapted to slidingly support a locking bolt 14 said bolt 14 being biased outwardly from said casing 12 by the use of a spring (not shown). The bolt 14 includes a sunken shoulder 16 at one side of the bolt rear end, said shoulder supporting an annular projection 18 . The bolt 14 is adapted to slide generally in a perpendicular axis 20 to the longitudinal axis 22 of the casing 12 . A lock case 24 limits the outward movement of said bolt.
A slider 26 is adapted to slide along the longitudinal direction 22 within the casing 12 and includes a first longitudinal slit 28 engaging a screw 30 , the screw 30 providing holding support for the lock 10 .
The slider 26 includes a second slit 32 extending at an inclined direction to both the perpendicular and the longitudinal axis 20 and 22 respectively. Slit 32 engages projection 18 of the shoulder 16 . One can thus appreciate that when the slider is moved towards the bolt, the inclination of the slit 32 causes the bolt 14 to be extended outwardly from said casing 12 . Conversely, when the slider 26 is moved in a direction away from the bolt 14 , the slit 32 acting on the shoulder projection 18 urges the bolt 14 to be withdrawn into the casing 12 . When locked, the slider 26 is maintained through use of a biasing member 34 , which may be indexed with a recess in the lid (not shown), for example.
The slider 26 may further include a shoulder 36 adapted to abut against face 38 in the casing 12 to act as a dead stop for the slider motion.
The end of the slit 32 where the bolt is caused to extend out of said casing includes a hooked portion 40 where the slit extends in a longitudinal direction parallel to the casing and thus perpendicular to the movement of the bolt. This has the advantage that when the projection 18 is located within the hooked location 40 , the slider effectively deadbolts the bolt. That is, if the bolt experiences an inward force, the edge 42 of the hooked portion 40 of the slit 32 engages the projection 18 and prevents the bolt 14 from moving into the casing 12 . To keep the projection steady within the hooked portion the slit may include a slight annular recess (not shown).
It is the slider 26 that provides the motion for the movement of the bolt 14 into and outward of the casing 12 . To enable the slider 26 to be movable by both the primary (key) and secondary (electric motor) locking mechanisms requires a clutch mechanism that is now described.
The secondary locking means includes a rack 44 that is adapted to engage the slider 26 . The rack 44 includes at one end splines 46 that are driven by a gear 48 rotatably driven by a shaft 102 extending from the electric motor 100 . The other end of the rack includes a generally oval-shaped cavity 50 which extends only partially therethrough. An outwardly biased pin 52 is positioned within the cavity 50 such that in its rest position, it extends beyond 53 of the rack 44 . The pin 52 contains a recess for housing the biasing member which in this case is a spring 54 . These parts of the lock can be seen more clearly in the exploded views of FIGS. 3-4 .
The slider 26 further includes an arm 56 with an aperture 58 extending therethrough. The aperture 58 is generally of the same shape as cavity 50 in rack 44 . Housed within aperture 58 is a cap 60 including a tapered shoulder 62 terminating into a head 64 . It should therefore be apparent that when aperture 58 and cavity 50 are coaxially aligned, pin 52 will be pushed through aperture 58 and abut the lower surface of cap 60 . Arm 56 includes a recess 67 to allow for movement corresponding with the primary locking mechanism which will be later explained.
Further included is a carriage 68 . Carriage 68 includes a carriage pocket 70 and carriage aperture 72 extending therethrough. A lock barrel or cylinder 74 rotatably fixed to the casing 12 includes a cam 76 that upon rotation of the key barrel is correspondingly rotated. The cam 76 is adapted to be housed within carriage aperture 72 and during the locking and unlocking processes, the cam 76 correspondingly follows the movement of the carriage 68 . It is during this process that recess 67 is required to allow for the cam rotation. Carriage 68 is shiftable along slider 26 to the extent provided by a locking cavity 78 on arm position. As there is no force provided by cam 76 , the cap 60 remains in the central position of the pocket 70 thereby allowing pin 52 to constantly abut surface 88 . Then, on operation of the electric motor to unlock the bolt 14 , the pin 52 acts on surface 90 of slider aperture 58 to shift the slider 26 in the opposite direction.
One can thus appreciate that the above operation, in using a secondary locking mechanism, is capable of locking and unlocking the lock 10 independent of the primary locking mechanism, that being operative use of the cam 76 .
FIGS. 6-9 illustrate the primary locking mechanism which involves the use of a key being inserted into the key barrel and rotated, thereby rotating cam 76 . More specifically, FIG. 6 illustrates the way the primary locking mechanism may function while the secondary locking mechanism is disengaged, FIG. 7 illustrates a continuation of this same locking action, while FIGS. 8 and 9 illustrate the fully locked and fully unlocked configurations of the lock 10 respectively.
Those skilled in the art would appreciate that when cam 76 is rotated in order to lock the lock 10 , it is caused to abut surface 92 of carriage aperture 72 . Therefore, carriage 68 is forced to longitudinally shift relative to the slider 26 . As can be seen in FIG. 6 , this action causes tapered surface 82 of carriage pocket 70 to push against tapered shoulder 62 of cap 60 . Cap 60 is forced into its carriage frame and the tapered surfaces continue to slide until the side of head 64 of cap 60 abuts with surface 94 of pocket 70 . This action not only causes pin 52 to be forced into cavity 50 due to the force applied by cap 60 , but also provides for a mechanical connection between the cam 76 and the slider 26 to thereby shift the slider 26 with further rotation of the cam 76 . Essentially, connection between the slider 26 and rack 44 is broken due to the resulting shear plane between rack and slider while connection between slider 26 and cam 76 is achieved.
With continued rotation of the cam 76 , the bolt is drawn into the extended and deadlocked position. It is to be understood that the deadlocked configuration of the bolt 14 is not achieved through the primary locking mechanism but rather through pocket 40 . If the primary locking mechanism did involve its own deadlocking feature, unlocking the bolt 14 using the secondary locking mechanism would not be possible. It should therefore be clear that the present invention provides for two independent means of locking and unlocking bolt 14 .
When unlocking lock 10 , which is to drive bolt 14 within the casing 12 , the key is obviously rotated in the opposite direction. Therefore, cam 76 is forced to abut with surface 96 of carriage aperture 72 thereby causing carriage 68 to shift in the opposite direction as described above, with the cap 64 forced to abut the opposite surface of carriage pocket 70 .
In the situation where the bolt has been unlocked using the primary locking mechanism and is required to be locked once again using the secondary locking mechanism, the electric motor when operated will drive the rack until the rack cavity 50 is coaxially aligned once again with slider aperture 58 such that spring 54 forces pin 52 back into abutment with cap 60 such that the slider 26 and rack 44 are now re-coupled for the electric motor to drive the lock.
One can thus appreciate how the present invention may be used to unlock a lock that has been locked by an electric motor that is still in the locked position. This is advantageous where the electric lock is to be overridden or where it has broken down. Use of the primary locking mechanism thus allows the lock to still operate even where the electric motor can no longer function.
It is to be understood that once the secondary locking mechanism has been disengaged, it remains motionless due to the gearing of the electric motor. Essentially, gearing back movement is prevented and thereby allows sufficient force to be applied to the slider to overcome tension that may be acting on the slider due to pin 52 which remains outwardly biased.
In a further aspect of the invention, the actions of the electric motor may well be governed by the use of a microprocessor in electrical connection with both the electrical motor and an arrangement of micro-switches which sense whether the slider is in a locked or unlocked position. The primary function of the processor is to process information gained from the micro-switches and to correspondingly operate the electric motor. One advantage to such a system over existing systems is that there is no longer the requirement for operating the motor for a predetermined amount of time to ensure that locking or unlocking has taken place and considerable battery power consumed in the process.
If under any circumstances the lock should fail to lock, the processor will realize that the lock is neither in a locked or unlocked state and sound an audible alarm to inform the user that the lock has not been successfully locked.
Further, the apparatus may well include a remote access means such as an infrared receiver such that locking and unlocking of the lock may be achieved from a remote location using a transmitting means. Further still, the apparatus may include an interrogation means so that a user may determine whether the bolt is in a locked or an unlocked position some distance away.
In some circumstances, a further bolt system may be engaged simultaneously with the dual lock of the present invention whereby the apparatus is in mechanical connection with one or more further bolts used to lock or unlock the door whereby the slider 28 is in mechanical connection with the bolts.
So as to keep the door from freely swinging when in the unlocked position, the lock mechanism may include a spring-loaded latch (not shown) being outwardly biased by a biasing means (not shown).
It is to be understood that other secondary driving means may equally well be employed. The rack may be acted upon by use of a manually operated crank (not shown).
In general the term deadlocking is intended to mean that when the lock is deadbolted, that the slider is effectively prevented from any slidable motion.
The above description generally referred to the slider being movable by a key activating the primary locking mechanism and an electric servomotor driving the secondary locking mechanism. It may equally well be, however, that the secondary locking mechanism is also activated by the use of a solenoid. However the electric motor provides much higher torques required especially where the lock arrangement includes multiple bolts such as additional upper and lower bolts. Even further still the secondary locking mechanism may also include a key activated lock accessible from one or both sides of the lock case or other types of simple non-secure actuators.
The present invention may also equally well be adapted for use on existing doors by the use of simple but effective adaptive pieces.
Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.
In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprising” is used in the sense of “including”, i.e. the features specified may be associated with further features in various embodiments of the invention.
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The present invention relates to a dual lock apparatus ( 10 ) of the type including a locking bolt ( 14 ) moveable between a first locked position and a second unlocked position said bolt movement corresponding with longitudinal movement of a slider ( 26 ) said apparatus including a first and a second locking means adapted to operate independently of one another. The first locking means ( 74 ) includes a rotatable cam ( 76 ) such that when rotated said cam acts against a moveable piston to thereby move said piston from a first position to a second position in which the second locking means becomes disengaged from said slider and further rotation of the cam urges longitudinal movement of the slider. The second locking means includes an electric motor in geared connection to a member ( 44 ) moveable between a first position and second position corresponding with the locked and unlocked positions of the bolt said member including an outwardly biased pin ( 52 ) adapted to engage the piston cylinder ( 58 ) and urge said piston into said piston first position to thereby mechanically connect the second locking means with the slider. The locking means can therefore operate independently of one another.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent application Ser. No. 11/618,619 filed on Dec. 29, 2006, incorporated herein by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC
[0003] Not Applicable
NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION
[0004] A portion of the material in this patent document is subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all copyright rights whatsoever. The copyright owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. § 1.14.
BACKGROUND OF THE INVENTION
[0005] 1. Field of the Invention
[0006] This invention pertains generally to an implantable distraction device, and more particularly to a cervical distraction device.
[0007] 2. Description of Related Art
[0008] Chronic back problems cause pain and disability for a large segment of the population. Adverse spinal conditions are characteristic of age. With aging, generally comes an increase in spinal stenosis (including, but not limited to, central canal and lateral stenosis), and facet arthropathy. Spinal stenosis results in a reduction of foraminal area (i.e., the available space for the passage of nerves and blood vessels) which compresses the cervical nerve roots and causes radicular pain. Extension and ipsilateral rotation of the neck further reduces the foraminal area and contributes to pain, nerve root compression, and neural injury. However, neck flexion generally increases the foraminal area.
[0009] Cervical disc herniations predominantly present with upper extremity radicular symptoms. The vast majority of these herniations do not have an associated neurologic deficit and present with pain only. A well-described treatment for cervical disc herniations is closed traction. There are a number of marketed devices that alleviate pain by pulling on the head to increase foraminal height.
[0010] Cervical disc herniations have been treated with anterior and posterior surgery. The vast majority of these surgeries are performed through an anterior approach, which requires a spinal fusion. These surgeries are expensive and beget additional surgeries due to change in biomechanics of the neck. There is a 3% incidence of re-operation after cervical spine surgery.
[0011] Therefore, an object of the present invention is to provide a minimally invasive device and surgery to increase foraminal height reduce radicular symptoms for patients with disc herniations.
[0012] At least some of these objectives will be met in the following disclosure.
BRIEF SUMMARY OF THE INVENTION
[0013] A device and technique are disclosed for a minimally invasive surgical implantation to reduce radicular symptoms by inserting an expandable cervical distraction implant in the facet joint at an affected level to preserve the physiology of the spine. In particular, embodiments of the present invention provide for distracting the cervical spine to increase the foraminal dimension in extension and neutral positions. The implant of the present invention, when positioned in the cervical facet joint, expands to distract, or increase the space between, the vertebrae to increase the foraminal area or dimension, and reduce pressure on the nerves and blood vessels of the cervical spine.
[0014] The procedure may be performed under conscious sedation in order to obtain intra-operative patient symptom feedback.
[0015] When the distraction implant is optimally positioned in the facet joint, it is injected with a bio-inert hydrogel using a catheter inflation syringe with pressure/volume monitor. The injection of the hydrogel causes the implant to expand in order to achieve cervical distraction. At this point in the procedure, patient feedback regarding symptom improvement could be obtained.
[0016] After achieving the desired distraction, the catheter is detached from the distraction implant and be removed. The patient is left with the distraction implant expanded in the facet joint with permanent increased foraminal height.
[0017] Aspect of the invention is an apparatus for distracting first and second adjacent vertebrae. The apparatus has an expandable implant configured to be inserted in a collapsed configuration within a facet joint bounded by the first and second vertebrae, and expand within the facet joint to increase a foraminal dimension, e.g. foraminal height associated with the first and second adjacent vertebrae.
[0018] Preferably, the expandable implant is configured to be installed in a facet joint located between at least one cervical vertebra. However, other locations are contemplated.
[0019] In one embodiment, the expandable implant is configured to engage the articulating surfaces of the facet joint to increase the distance between the articulating surfaces, the distance correlating to the foraminal dimension.
[0020] The expandable implant may comprises an inflatable balloon configured to be filled with an inflation medium, e.g. hydrogel or the like, to distribute a compressive load on the articulating surfaces.
[0021] Generally, the facet joint has a joint capsule that extends beyond the margin of the articulating surfaces. In a preferred embodiment, the expandable implant is configured to be delivered into the facet joint through an access hole created in the joint capsule. The expandable implant is ideally configured such that, in its expanded configuration, is larger than the access hole so that the expandable implant is retained in the facet joint once expanded. The expandable implant may also be configured to plug the access hole once expanded. Typically, the expandable implant is configured to occupy a substantial portion of the depth of the facet joint once expanded.
[0022] In another preferred embodiment, the expandable implant is configured to dynamically stabilize the facet joint. Generally, the expandable implant increases and maintains a minimum distance between the articulating surfaces, while allowing motion of the first vertebrae with respect to the second vertebrae.
[0023] For delivery, the expandable implant preferably attaches to a distal tip of a catheter to facilitate installation into the facet joint. The catheter transports the inflation medium into the expandable implant. The expandable implant is configured to detach from the catheter once the implant is expanded in the facet joint.
[0024] Another aspect is a method of minimally invasively distracting first and second adjacent vertebrae. The method includes the steps of inserting an expandable implant, in a collapsed state, into a facet joint bounded by the first and second vertebrae, and expanding the expandable implant within the facet joint to increase a foraminal dimension associated with the first and second vertebrae.
[0025] In a preferred embodiment, the expandable implant is installed in a facet joint located between at least one cervical vertebra. The expandable implant engages the articulating surfaces of the facet joint to increase the distance between the articulating surfaces.
[0026] In many embodiments, inserting an expandable implant is achieved by creating an access hole through the joint capsule, and inserting the expandable implant in a collapsed configuration through the access hole and into the facet joint. Typically, the access hole is created with an introducer needle used to deliver the expandable member.
[0027] In a preferred embodiment, an inflatable balloon is filled with an inflation medium causing the balloon to engage the articulating surfaces the expandable implant. A compressive load is imparted on the articulating surfaces to distract the first vertebra from the second vertebra.
[0028] To inflate the expandable implant, a catheter is fed through the access hole and into the facet joint with the expandable implant attached to a distal tip of a catheter. An inflation medium is then delivered into the expandable implant via the catheter to inflate expandable implant with the inflation medium. Once inflated, the expandable implant detaches from the catheter once the implant is expanded in the facet joint.
[0029] Dynamic stabilization of the facet joint is affected as a result of the expanded implant being disposed between the articulating surfaces of the facet joint. The distance between the articulating surfaces is maintained while allowing motion of the first vertebrae with respect to the second vertebrae.
[0030] In one embodiment, the extent of inflation of the expandable member is determined via patient feedback while the expandable member is being inflated.
[0031] Another aspect is a system for distracting a first vertebra from a second adjacent vertebra. The system includes a catheter and an expandable implant configured to be detachably installed in a collapsed configuration on the distal tip of the catheter. The expandable implant and catheter are configured to be inserted in into a facet joint bounded by the first and second vertebrae to expand the expandable implant within the facet joint to increase a neural foraminal height associated with the first and second vertebrae.
[0032] Further aspects of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0033] The invention will be more fully understood by reference to the following drawings which are for illustrative purposes only:
[0034] FIG. 1 is a lateral view of two cervical vertebral members in a stenosed condition.
[0035] FIG. 2 is a view of an introducer needle being inserted into the facet joint of the vertebral members in accordance with the present invention.
[0036] FIG. 3 illustrates an implant of the present invention being inserted into the facet joint.
[0037] FIG. 4 . illustrates the implant of FIG. 3 in an expanded configuration.
[0038] FIG. 5 illustrates the implant of FIG. 4 with the catheter detached from the implant and removed from the treatment site.
[0039] FIG. 6 is another view of the placement of the implant in the facet joint in accordance with the present invention.
[0040] FIG. 7 is an expanded view of the implant installed in a collapsed configuration on a catheter.
[0041] FIG. 8 illustrates the implant of FIG. 7 in an expanded configuration.
[0042] FIG. 9 illustrates an implant of the present invention having a circular cross-section.
[0043] FIG. 10 illustrates an implant of the present invention having an oval cross-section.
[0044] FIG. 11 illustrates an implant of the present invention having a rectangular cross-section.
[0045] FIG. 12 illustrates an implant of the present invention having 2-piece design.
[0046] FIG. 13 illustrates an implant of the present invention having a taper along its length.
DETAILED DESCRIPTION OF THE INVENTION
[0047] Referring more specifically to the drawings, for illustrative purposes the present invention is embodied in the apparatus generally shown in FIG. 2 through FIG. 13 . It will be appreciated that the apparatus may vary as to configuration and as to details of the parts, and that the method may vary as to the specific steps and sequence, without departing from the basic concepts as disclosed herein.
[0048] FIG. 1 illustrates a simplified lateral view of a portion of the cervical spine 10 . The basic biomechanical unit or motion segment of the spine consists of two adjacent vertebrae 12 and 14 and the three joint articular complex through which they move and are constrained in relation to one another. The spine articulations generally consist of an intervertebral disc 26 located between the vertebral bodies 26 of adjacent vertebrae 12 , 14 , and two facet joints 16 symmetrically located laterally from the sagittal plane at the posterior end of the vertebral bodies 26 .
[0049] The facet joints 16 allow constrained spinal motion, while protecting the contained neural structures. From a kinematic viewpoint, the intervertebral facet joints 16 are highly constrained sliding planar articulations, lubricated by synovial fluid contained within the facet joint capsule 30 . In the cervical spine, the geometry of the cervical vertebral bodies provides a high degree of protection for the neural elements by limiting normal motion of the spine to within physiologic limits. The upward inclination of the superior articular surfaces of the facet joints allows for considerable flexion and extension, as well as for lateral mobility.
[0050] Minimally invasive surgical access to the facet joint is well documented. Each vertebral segment comprises a spinous process 34 located at the posterior end of the vertebrae, with the vertebral body located anteriorly. Each vertebra comprises an inferior articular (or transverse) process 35 and the superior articular process 37 that form four posterior articulating, e.g. opposing subchondral, surfaces: two superior facets 18 and two inferior facets 16 . The inferior facet 18 from the inferior articular process 35 of the upper vertebra 12 and the superior facet from the superior articular process 37 of the lower vertebra 14 form the facet joint 16 on each lateral side of the spine.
[0051] Located medial to the articular processes 37 and vertebral bodies 26 is an aperture, or intervertebral foramina 38 , that serves as a nerve root canal for the spinal nerves and vessels that transmit signals from the spinal chord to respective locations in the body.
[0052] Each facet joint 16 is covered by a dense, elastic articular capsule 28 , which is attached just beyond the margins of the articular facets 18 , 22 . The inside of the capsule is lined by a synovial membrane (not shown) which secretes synovial fluid for lubricating the facet joint. The exterior of the joint capsule is surrounded by a capsular ligament (not shown), which may be temporarily repositioned to give access for insertion of the extendable implant of the present invention, described in further detail below. Thus, from a posterior-lateral approach, access to the facet joint 16 is relatively straightforward and well prescribed, as compared to other regions of the spine which present a higher likelihood of trauma and risk of permanent damage.
[0053] It should also be noted that FIG. 1 depicts cervical foraminal stenosis, e.g. loss of height between the adjacent vertebrae 12 , 14 . As a result of disc 36 herniation and corresponding height loss, the nerve root canal 38 , or intervertebral foraminal height, having a value H s , is narrowed relative to that of healthy anatomy. This narrowing of the foraminal height H s often leads to compression of the spinal cord and nerve roots (not shown), causing radicular symptoms.
[0054] As a result of the stenosed foraminal height H s , the height of the facet joint 16 , or distance between subchondral articulating surfaces 18 and 22 , is also narrowed, (shown as value D s in FIG. 1 ). This may pose complications in the facet joint 16 as well. However, more importantly, because the height of the disc will be relatively fixed, an increase in the facet joint height will also have a corresponding increase in foraminal height, as described in greater detail below.
[0055] FIGS. 2-6 show the methods and system 50 of the present invention for performing a minimally invasive procedure configured to distract one or more of the facet joints 16 of vertebrae 12 , 14 , thereby increasing the dimension of the neural foramen while retaining facet joint mobility. One of the major advantages of minimally invasive surgery is the ability to perform the procedure with minimal tissue trauma. Television image intensifier fluoroscopy may be used to provide guidance for surgeon placement of instrumentation and implants precisely to the desired anatomic target in the facet joint 16 . The radiographic landmarks are well taught and the relative procedural difficulty of this technique is low.
[0056] Referring to FIG. 2 , a standard discography introducer needle 44 (e.g. approximately 21 gauge needle) is be inserted into the outer facet capsule 28 to create a perforation or access hole 32 into the facet joint cavity 30 . Dye may then be injected through the introducer needle 44 to fluoroscopically confirm that the introducer needle 44 is in the facet joint cavity 30 .
[0057] Referring now to FIG. 3 , a catheter 52 having an expandable implant 60 coupled to the distal end 54 of the catheter 52 , may then be guided over into the facet joint cavity 30 through needle 44 such that the distal tip 42 of the implant is located in the proper position in cavity 30 .
[0058] Once the implant 60 is placed at the correct location of the facet joint 16 , the implant is injected with a bio-inert hydrogel to inflate the catheter. Inflation may be achieved with a catheter inflation syringe 56 , and the pressure and/or volume may be observed via monitor 58 . Further visualization may be achieved by including a contrast dye within the hydrogel. The hydrogel and expandable balloon may be similar to the materials found in the HyperGlide Occlusion Balloon Catheter by Micro Therapeutics, Inc., used for vascular occlusions.
[0059] FIG. 4 illustrates the implant 60 in an expanded configuration within the facet joint. As shown in FIG. 4 , the hydrogel-inflated expandable implant 60 generates an outward compressive force F on the subchondral surfaces 18 and 22 to increase the distance between them to a desired treatment or nominal value D T . This correspondingly increases the height of the intervertebral foramin to a treatment or nominal value H T . The value of D T , and resulting increase in H T may be predetermined by the surgeon prior to the surgery based on pre-op analysis of the patient's condition and anatomy, and/or may also be iteratively devised by patient feedback of symptom improvement during the procedure.
[0060] The size of implant 60 is configured to distract the joint and reverse narrowing of the nerve root canal 38 and alleviate symptoms of cervical stenosis. However, it is also within the scope of the present invention to size the implant according to other spinal conditions, for example to correct for cervical kyphosis or loss of cervical lordosis.
[0061] Once the desired inflation/distraction is achieved, the catheter 52 is detached from the implant 60 , and fed out of the patient's body. Referring now to FIG. 5 , the expanded implant 60 will occupy the joint cavity 30 such that it will occlude the opening 32 in the facet capsule 28 . Because the inflated implant 60 is larger than the opening 32 caused by the violation of the joint by the introducer needle 44 , the implant 60 acts as a plug to close off the joint cavity 30 . In addition, because the implant is confined within the boundaries of the joint cavity 30 , including the facet surfaces 18 , 22 and capsule 28 , it will remain in its installed position without further anchoring to hold the device in place. Due to the properties of synovial joints and the configuration of the implant 60 , it is unlikely that the implant 60 will extrude from the joint once it has been implanted. If further constraint is desired, the external walls of the balloon may be fabricated to have a surface roughness or texture configured to inhibit motion with respect to the walls 18 , 22 of the facet joint.
[0062] If symmetrical distraction is desired between the adjacent vertebrae, the procedure may be repeated for the second facet joint located between the target vertebrae. However, it is contemplated that only one implant may be necessary to alleviate radicular symptoms.
[0063] FIG. 6 illustrates a preferred placement of the implant 60 within the facet joint 16 . The average width of the cervical facet is approximately 9 mm. The average depth of the cervical facet is also approximately 9 mm. The preferred location of the capsule is generally the center third of the facet joint cavity 30 , as its approximate size will be about 3-4 mm in width, as shown in FIG. 6 . The length of the implant 60 will be approximately 8-9 mm, or roughly the depth of the facet joint cavity 30 , and therefore may preferably occupy all or nearly all of the joint depth. Preferably, the implant 60 will be configured to expand to up to a height of approximately 3 mm or more. It is appreciated that the above sizing of the implant may vary accordingly to accommodate patient anatomy, condition, or desired foraminal height increase or other preferences defined by the surgeon.
[0064] The size, configuration, and placement of implant 60 are configured to provide distraction of the facet joint, while also preserving the mobility between the adjacent vertebrae 12 , 14 . For example, translation of the articular surfaces 18 , 22 with respect to each other (e.g. along the plane of the surfaces) is not restrained, while the undesired translation normal to the articular surfaces 18 , 22 , (e.g. collapsing), is inhibited. Additionally, the adjacent vertebrae 12 , 14 are allowed to rotate about the long axis of the implant 60 with respect to each other, as well as rotate about the spinal column axis. Thus, the implant 60 of the present invention allows for dynamic stabilization and distraction of the facet joint to increase and maintain foraminal height.
[0065] FIG. 7 illustrates an expandable balloon implant 60 in a collapsed configuration and attached to distal end 54 of catheter 52 . The walls 72 of the balloon may be folded over along the length L of the balloon to minimize the profile of the balloon 60 .
[0066] FIG. 8 illustrates expandable balloon implant 60 in its expanded configuration. Balloon implant 60 is generally comprised of one or more exterior walls that are configured to hold and retain the inflatable medium, e.g. hydrogel. In some embodiments, the implant 60 may have a central lumen (not shown), emanating at proximal end 76 , and terminating at distal end 74 through the length L of the balloon. The central lumen allows the implant 60 to be fed over a guide wire, or like device, to the target location in the facet joint 16 .
[0067] The proximal end 76 will also have a port 70 allowing flow of the inflation medium into the bladder of the balloon. This port 70 may be self-sealing, wherein the port automatically seals upon detaching catheter 52 , or may incorporate a plug (not shown) or other sealing mechanism that may be fed over guide wire 40 to close and seal up port 70 once the catheter 52 is removed.
[0068] The cross section of the implant may comprise a variety of different shapes, as shown in FIGS. 9-12 . In FIG. 9 , balloon implant 80 comprises an outer wall 82 having a generally circular shape, thus creating a cylindrical structure across the length of the balloon. The thickness T of the external wall 82 is configured to withstand the compressive loads associated with the facet joint in the cervical spine, and may be varied accordingly. With the cylinder shape implant 80 , the outer wall will generally contact and engage the facet surfaces 18 , 22 in a line down the depth of the facet cavity 30 . The diameter D of the outer wall 82 will be sized for the desired increase of the foraminal height, e.g. ranging from approximately 1 mm to over 3 mm.
[0069] As illustrated in 10 , balloon implant 90 may comprise a elliptical or oval cross section, having a height H sized for desired increase of the foraminal height, and width W. A rectangular cross section may also be used, as shown with implant 100 of FIG. 11 .
[0070] The implants 80 , 90 and 100 may be fabricated by a number of methods currently available in the art. For example, the implant may be formed as a single piece structure over a mandrel (not shown) having varying cross section for the central lumen (if needed) and outer walls 82 , 92 , 102 .
[0071] In an alternative embodiment shown in FIG. 12 , the balloon 110 may comprise a bladder having upper wall 114 and lower wall 115 that are heat sealed at the sides 112 .
[0072] As illustrated in FIG. 13 , the balloon may also be tapered along its length to accommodate the anatomy of the facet joint 16 , as seen with balloon 120 , wherein the leading or distal end 124 has a smaller profile than the trailing or distal end 126 .
[0073] The extendable implants above may comprise an elastic material, e.g. biocompatible polymer, which allows the implant to expand to a varying range in sizes. Alternatively, the implant may comprise an inelastic material that has a maximum inflation capacity, and wherein a number of predetermined sizes may be available to the surgeon according to the desired size determined by the surgeon.
[0074] The implant 60 will generally be sized to accommodate the geometry of the patient anatomy and target foraminal height. For cervical herniations, the implant 60 will typically be installed from the C4/C5 joint down to C7/T1 (95% of all cervical herniations occur at C5/6 & C6/7). The height of the implant 60 may range from approximately 1 mm to over 3 mm, depending on the patient anatomy. For the cylindrical-shaped balloon 80 of FIG. 9 , the width will roughly equal the height. However, as shown in FIGS. 10-12 , the width may be increased for the desired stabilizing effect.
[0075] Although the embodiments disclosed above are directed primarily to installation in the cervical facet joint, it is contemplated that the devices and methods may also be used to increase foraminal dimension in other regions of the spine, e.g. thoracic, lumbar, etc.
[0076] Although the description above contains many details, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Therefore, it will be appreciated that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112, sixth paragraph, unless the element is expressly recited using the phrase “means for.”
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A device and method for a minimally invasive surgical implantation to reduce radicular symptoms by inserting an expandable cervical distraction implant in the facet joint and distracting the adjacent cervical vertebrae to increase the foraminal dimension. The implant, when positioned in the cervical facet joint, expands to via delivery of an inflation medium to increase the space between the vertebrae, thereby increasing the foraminal area or dimension, and reducing pressure on the nerves and blood vessels of the cervical spine.
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This application is a National Stage Application of International Application No. PCT/IN07/00402, filed Sep. 10, 2007, which claims priority to Indian Patent Application No. 2835/DEL/06, filed Dec. 29, 2006, each of which is incorporated by reference herein in its entirety.
SEQUENCE LISTING
The instant application contains a Sequence Listing which has been submitted in ASCII format via EFS-Web and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Aug. 8, 2012, is named 31446278.txt and is 7,379 bytes in size.
FIELD OF INVENTION
This invention relates to an active peptide derived from a protein that interacts with p53 antitumor factor and activates, leading to suppression of neoplastic growth.
BACKGROUND OF THE INVENTION
Despite tremendous efforts in molecular, biochemical and cell biological research towards understanding the intra- and extra-cellular mechanisms involved in the transformation of a normal cell into a cancerous one, the number of successful treatments against cancer is few. A major limitation of cancer therapeutics is the problem of delivering pharmacologically relevant compounds, peptidyl mimetics, antisense oligonucleotides, and proteins into cells (Egleton, R. D., and Davis, T. P. (1997) Peptides 18, 1431-1439). Peptide-based drugs have limitations in the form of the poor permeability and selectivity of the cell membrane. These problems are now circumvented by attaching protein translocation domains (PTDs) to the peptides that, can cross the biological membranes efficiently without any dependence on transporters or specific receptors and mediate the intracellular delivery of a range of biological cargos (Schwarze, S. R., Hruska, K. A., and Dowdy, S. F. (2000) Trends Cell Biol. 10, 290-295; Ford, K. G., Souberbielle, B. E., Darling, D., and Farzaneh, F. (2001) Gene Ther. 8, 1-4). The PTD of HIV-1 Tat protein in well-known to mediate transduction of heterologous peptides and biologically active proteins in vitro and in vivo (Ho, A., Schwarze, S. R., Mermelstein, S. J., Waksman, G., and Dowdy, S. F. (2001) Cancer Res. 61, 474-477) and thus has been shown to be of considerable interest for protein therapeutics (Schwarze, S. R., Ho, A., Vocero-Akbani, A., and Dowdy, S. F. (1999) Science 285, 1569-1572).
The integrity of the eukaryotic genome requires several layers of control to ensure that replication of DNA occurs only once during a cell cycle (Elledge, S. J. (1996) Science 274, 1664-1672). For normal cellular functions and tissue homeostasis, accurate transmission of genetic information between generations is required. Dysregulation of the cell cycle control is a hallmark of cancer (Hanahan, D., and Weinberg, R. A. (2000) Cell 100, 57-70). Neoplastic progression has been demonstrated to involve increased genetic instability (Donehower, L. A. (1997) Cancer Surv. 29, 329-352; Harley, C. B., and Sherwood, S. W. (1997) Cancer Surv. 29, 263-284) and there are enough reports revealing that the disruption of multiple pathways is required for the development of cancer (Hunter, T. (1997) Cell 88, 333-346). Inactivation or loss of p53 is a common event associated with the development of approximately 60% of
all human cancers (Levine, A. J. (1997) Cell 88, 323-331; Michael, D., and Oren, M. (2002) Curr. Opin. Genet, Dev. 12, 53-59). The tumor suppressor protein p53 is a short lived, latent transcription factor that is activated and stabilized in response to a wide range of cellular stresses, including DNA damage and activated oncogenes. p53 has been shown to participate in the regulation of several processes, which might inhibit tumor growth, including differentiation, senescence and angiogenesis (Vogelstein, B., Lane, D., and Levine, A. J. (2000) Nature 408, 307-310; Oren, M. (2003) Cell Death, Differ. 10, 431-442). However, central to the function of p53 appears to be the ability to induce both cell cycle arrest and/or apoptosis in stressed cells, partly by activating expression of p53 responsive target genes that mediate these responses (Ashcroft, M., Taya, Y., and Vousden, K. H. (2000) Mol. Cell. Biol. 20, 3224-3233; Woods, D. B., and Vousden, K. H. (2001) Exp. Cell Res. 264, 56-66). Since p53 maintains the genetic stability, it must be under rigorous and complex control. Highly conserved residues in its N- and C-terminal domains are targets for potential post-translational modification via phosphorylation, ubiquitination or acetylation (reviewed by Giaccia and Kastan, 1998: Michael, D. and M. Oren. 2003. Semin. Cancer Biol. 13:49-58). The precise mechanism of p53 activation by cellular stress is of intense interest and may involve both increase in p53 protein level and in the specific activity of p53 by covalent modifications (Harris. S. L., and Levine, A. J. (2005) Oncogene 24, 2899-2908.
The present investigations were aimed at using the protein translocation domain (PTD) of Tat protein to deliver short peptide sequences of tumor suppressor protein SMAR1 both in vitro and in vivo. SMAR1, a recently identified MARBP, was isolated from double positive mouse thymocytes (Chattopadhyay et al., 2000, Genomics). SMAR1, a 68 KDa protein has been previously shown to interact with p53 (Jalota et al., 2005). SMAR1 exists in two alternatively spliced forms: SMAR1 L and SMAR1 S , with deletion of 39 amino acids in the N-terminus and shares approximately 99% homology with its human homolog, BANP (Birot et al., 2000 Gene 253, 189-196). Interestingly, in numerous cancers, altered expression of several MAR binding proteins have been demonstrated (Liu, W et al., (1999) Cancer Res. 59:5695-5703). In the present work, we show that a 33-mer SMAR1 peptide conjugated to an 11-mer protein transduction domain (PTD) of HIV-1 TAT protein is sufficient enough to inhibit the tumor growth in nude nice. Exposure of cells to this peptide resulted in increased p53 phosphorylation at its serine 15 residue, in turn, activating the p53-mediated cell cycle control. Point-mutation studies of P44 peptide further revealed that the serine 347 residue within the serine-rich motif of SMAR1 plays a pivotal role in mediating the tumor suppressor effect of SMAR1. The 347 serine residue represents the substrate motif for the PKC family of proteins and its phosphorylation is necessary for activating the p53-dependent pathway. We also observe that tumors excised from mice treated with SM mutant peptide showed leaky vascular architecture compared to P44 treated tumors. Interestingly, there was no detectable level of HIF-1α in tumors from mice treated with SMAR1 peptide that is a hallmark of tumor hypoxia. Thus, our results implicate that this SMAR1 peptide can be used, as an alternative drug for cancer therapy.
Major research efforts are aimed at discovery of molecular targets that are specific as well as toxic to cancer cell. Identification of potential targets for therapeutic intervention thus fuels a hope for curing cancer. Peptide-mediated molecular therapeutic delivery systems have currently emerged as an alternative means to effectively substitute or augment present gene therapy technologies, e.g. TAT, VP22, engineered peptides. This invention potentiates the use of P44 peptide of SMAR1 for peptidometic cancer drug design so as to allow therapeutic intervention in the target cell biochemistry without the need to alter its genome.
Inactivation or loss of p53 is a common event associated with the development of approximately 60% of all human cancers. p53 has been shown to participate in the regulation of several processes which might inhibit tumor growth, including differentiation, senescence and angiogenesis. However, central, to the function of p53 appears to be the ability to induce cell cycle arrest and/or apoptosis in stressed cells, at least in part by activating expression of p53-responsive target genes that mediate these responses. Recently, Inventors have identified a novel peptide derived from MAR binding protein; SMAR1 that regulates cell cycle through modulating the activity of p53 and acts as a potent tumor regressor.
OBJECTS OF THE INVENTION
The object of the invention is to generate an active peptide that interacts with anti-tumor factor.
Other object is to generate an active peptide from a protein that interacts with p53 anti-tumor factor.
Further object is to produce shorter peptide of tumor suppressor protein SMAR1 that retains the potential to activate and stabilize p53 as much as the full length protein.
Yet another object is to evaluate the functionality of the peptide with respect to activation of p53 and p53-target genes.
Other object is to generate its mutant and to further identify the residue indispensable for its activity.
Further object of this invention is to use the active peptide for suppression of neoplastic growth.
Yet another objective is to use P44 peptide of SMAR1 for peptidometic cancer drug design to allow therapeutic intervention in the target cell biochemistry without the need to alter its genome.
DETAILED DESCRIPTION OF THE INVENTION
New revelations continue to emerge concerning the mechanisms that control p53 activation in response to a wide range of input signals. Diverse stimuli appear to invoke similar set of responses to achieve p53 activation: p53 must first accumulate in the nucleus, and then bind to DNA as a tetramer to transcriptionally regulate a growing list of target genes including p21, GADD45, 14-3-3-sigma, MDM2, IGF-BP3, cyclin G and bax (reviewed E1-Deiry, 1998: Oren, 2003). In the absence of stress, p53 is maintained at very low steady-state levels, and is thus prevented from exerting profound, effects on the cell phenotype. Multiple lines of evidence indicate that the lion's share of the negative regulation of p53, under nonstressed conditions, is performed by the Mdm2 protein (Michael and Oren, 2002: Daujat et al., 2001). Mdm2 binds at the N-terminal transactivation domain of p53 and blocks the critical interactions with other proteins necessary for p53 dependent gene regulation. It plays a cardinal role in the ubiquitnation-mediated proteasomal degradation of p53 under nonstressed conditions.
Various p53-modulating proteins have been identified so far that results in p53 activation in a DNA damage dependent manner (Banin et al., (1998) Science 281: 1674-1677; Zheng et al., (2002) Nature 419:849-853). We have reported another p53 interacting protein, SMAR1 (Scaffold/Matrix Associated Region). SMAR1, a recently identified MARBP, was isolated from double positive mouse thymocytes, (Chattopadhyay et al., 2000). It specifically binds to a putative MAR (MARβ), a DNase I-hypersensitivity site located 400 bp upstream of the transcriptional enhancer (Eβ) at the T-cell β locus. SMAR1 exists in two alternatively spliced forms: SMAR1 L and SMAR1 S , with deletion of 39 amino acids in the N-terminus. The SMAR1 gene maps to the distal portion of mouse chromosome 8 at a distance of 111.8 cM. Interestingly, in numerous cancers, altered expression of several MAR Binding proteins have been demonstrated. Both we-p53 and mutant p53 have also been shown to bind to the nuclear matrix (Jiang et al., (2001) Oncogene 20: 5449-5458). However mutant p53 binds with high affinity to variety of MAR-DNA elements resulting in base unpairing (Appella and Anderson, (2000) Pathol. Biol. (Paris) 48:227-245).
Uptake the nuclear compartmentalization of chimeric TAT PTD-SMAR1 derived peptides: Since the amino acids 288-350 play a critical role in p53 modulation (30) and in turn cell cycle regulation, we commercially synthesized shorter SMAR1 derived peptides to evaluate their efficacy in vitro and in vivo. Several reports have established that the chemical conjugation of the protein transduction domain (PTD) derived from HIV-1 TAT protein was able to induce cellular internalization of large proteins such as β-galactosidase or horseradish peroxidase (Fawell, S (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 664-668; Vocero-Akbani (2001) Methods Enzymol. 332, 36-49). With the prospect of using similar tools for drug delivery, it was of interest to design SMAR1-derived peptide and explore its mechanism of internalization. A 33 mer peptide sequence extending from residues 324-357 aa was conjugated with 11-mer TAT-PTD and designated as TAT-SMAR1 WT (P44). This short peptide sequence overlapped with the PKC substrate motif (the serine rich motif) of the full-length SMAR1, known to be involved in its phosphorylation and subsequent nuclear accumulation of p53. Various serine-mutants, where serine was replaced by alanine, of the P44 peptide (PS347A, PS348A, PS349A, and PS350A) and SMAR1 RS mutant (SM), were also commercially synthesized ( FIG. 1A ; Table 1). To understand the mechanism of uptake and intracellular compartmentalization of all these peptides, they were labeled with TRITC fluorochrome and purified using PD-10 column. Upon exposure of cells to either of the peptides, except the control ( FIG. 1B ), all others were observed to get localized into the nucleus ( FIG. 1C-H ). Internalization of all TAT-SMAR1 chimeric peptides within the nucleus occurred in a dose-dependent manner (data shown only for P44 peptide) ( FIG. 1I L) as observed by the intensity of the recorded signal. At a concentration of around 50 μM (that seemed to be saturating), TRITC-labeled peptides could also be detected in the cytoplasm ( FIG. 1L ). There was no overall variation in the uptake and localization between the various SMAR1-derived TAT conjugated peptides ( FIG. 1C-H ). A non TAT conjugated SMAR1 peptide labeled with TRITC was used as negative control which as expected, was not taken up the cells as recorded with no fluorescent signal ( FIG. 1B ). The results thus confirmed that the chimeric peptides of SMAR1 were efficiently translocated into the nucleus by TAT PTD.
TAT-SMAR1 WT peptide (P44) modulates p53 function: To examine whether P44 peptide could alone activate p53 − , luciferase reporter assays were performed following treatment of cells with the chimeric TAT-SMAR1 derived peptides. HEK 293 (p53 +/+ ) cells were transfected with p21 expression plasmid having luciferase reporter gene and K562 (p53 −/− ) cells were co-transfected with p21 luciferase reporter and p53 constructs. Treatment of cells with 10 μM of P44 peptide resulted in a 2-fold activation of p53 in p53 +/+ . ( FIG. 2A , bar 3) and about 1.5 fold activation in p53 −/− cell line ( FIG. 2B , bar 4). In the presence of P44 peptide alone, there was no activity in p53 −/− cells indicating that peptide itself does not transactivate the p53 responsive p21 promoter ( FIG. 2B , bar 3). However, point mutation at serine 347 residue (PS347A) as well as the SMAR1 RS mutant peptide (SM) resulted in complete loss of p21 promoter driven luciferase activity in both p53 WT and p53 null cell lines ( FIG. 2A , bars 4 and 8; FIG. 3B , bars 5 and 9, respectively). No significant alteration in activation of p53 was observed by peptides with point mutations at serine 348 (PS348A), serine 349 (PS349A) or serine 350 residue of SMAR1 (PS350A) ( FIG. 2A , bars 5-7; FIG. 2B , bars 6-8). Thus, these results indicate that serine-347 residue within the RS domain (288-350 aa) of SMAR1 is necessary for modulating p53 activity.
P44 peptide controls the activity of cell cycle regulatory proteins: The minimal dose of P44 peptide that was functionally effective in activating p53 was evaluated by incubating HEK 293 cells with varying concentrations of P44 peptide (1-100 μM) ( FIG. 3A ) and after 12 h of incubation, protein lysates were prepared and processed for immunoblotting with total p53 (DO-1) and p53 ser-15 phospho-specific antibodies. A slight increase in the total p53 expression was observed. However, there was a 4.5-fold increase in the expression of phosphorylated p53 (pSerine-15 p53) in P44 peptide-treated cells ( FIG. 3A , lanes 2-6). To exclude the possibility that p53 activation is an effect of the protein transduction domain of HIV-1 TAT protein, similar set of experiment was performed using TAT-PTD peptide alone (consisting of only the 11-mer TAT-sequence). As expected, no phosphorylation of serine-15 residue of p53 was observed in TAT-treated cells, although when used at a much higher concentration (50-100 μM) ( FIG. 3B , lanes 1 and 2) with respect to P44 peptide (5-10 μM) ( FIG. 3B , lanes 3 and 4). This observation reconfirmed that the RS domain (288-350 aa) of SMAR1 could exclusively activate p53 by mediating its phosphorylation specifically at serine-15 residue. Serine-15 phosphorylation of p53 is associated with its increased transcription efficiency, decreased affinity for MDM2, and its increased nuclear retention. One of the target genes activated by p53 is p21, an inhibitor of a subset of the cyclin-dependent kinases including cdc-2 (Sherr, C. J., and Roberts, J. M. (1999) Genes Dev. 13, 1501-1512). To evaluate the significance of peptide-mediated p53 activation, P44 peptide-treated lysates were further checked for tyrosine 15 phosphorylation of cdc2. Membrane immunoblotted with pcdc-2 antibody showed upregulation of pcdc-2 (FIG. 3 C, lanes 2-5) in comparison to only cells ( FIG. 3C , lanes 1), again confirming that P44 peptide was capable enough to mediate the effects of full-length SMAR1 and thus it may possess the entire functional activity to regulate the cell cycle. No changes were observed in the total ERK levels that were used as a loading control. TAT-SMAR1 RS-mutant peptide (SM) was further used to demonstrate that the serine motif (SSSSYS) of SMAR1 minimal domain (arginine-serine rich) is essential for mediating the effects of full-length SMAR1 in p53 activation signaling. HEK 293 cells were treated with SM peptide and checked for p53 as well as pcdc-2 levels. The SM peptide-treated lysates showed no increase both in the expression levels of p53 phospho-serine 15 or pcdc-2 levels when compared to untreated cells ( FIG. 3D ).
Serine 347 residue of SMAR1: critical for mediating the effects of full-length SMAR1: Once it was established that the serine motif (SSSSYS) plays a pivotal role in SMAR1-mediated p53 activation, it got necessary to identify the serine residue within this motif that might be necessary in mediating these effects. To identify the critical serine residue within P44 peptide, various point-mutant peptides were custom synthesized, that varied with respect to the position of serine residue that was mutated (Table 1). To evaluate the functionality of mutant chimeric TAT-SMAR1 peptides [PS347A, PS348A, PS349A, PS350A and RS mutant (SM)] in comparison to the TAT-SMAR1 WT peptide (P44), HEK 293 cells were treated with 10 μM concentration of either of the peptides and protein lysates were prepared after 12 h incubation period. The lysates were then processed for immunoblotting with pSer-15 p53 and pcdc-2 antibodies. Inventors observed that when the first serine residue of P44 peptide was replaced with alanine (PS347A), there was no significant activation of p53 ( FIG. 4A , lane 2) thus, demonstrating the significance of serine 347 residue of SMAR1. The increase in the pcdc-2 levels that was observed in case of P44 ( FIG. 5A , lane 6) was decreased in PS347A treated cells ( FIG. 4A , lane 2). However, this was not the case with other mutated peptides. When the alanine was replaced back to serine at the 347 residue ( FIG. 4A , lanes 3-5), the functionality of the peptide was restored as observed with increase in pcdc-2 levels. No significant decrease in p53 activation and subsequent increase pcdc-2 was observed between various P44 mutant peptides; PS348A, PS349A and PS350A ( FIG. 4A , lanes 3-5). However, in case of SM (where serine residues from 347-350 were replaced by alanines) treated cells ( FIG. 4A , lane 7), there was no difference in the pSer-15 p53 as well as pcdc-2 levels compared to either untreated or PS347A treated cells ( FIG. 4A , lanes 1 and 2, respectively). These observations strongly suggest that the first serine residue of the SMAR1 serine motif if most critical and essential for SMAR1-mediated p53 activation.
In a similar approach, immunofluorescence studies were performed to demonstrate p53 stabilization upon peptide treatment. HEK 293 cells were treated with 10 μM of various TAT-SMAR1 derived peptides. After 12 h of incubation, cells were indirectly stained for p53 and counterstained with FITC and the expression of p53 was observed with confocal imaging. As demonstrated in our earlier report that SMAR1 overexpression results in increased retention of activated p53 within the nucleus (Jalota, A., Singh, K., Pavithra, L., Kaul-Ghanekar, R., Jameel, S., and Chattopadhyay, S. (2005) J. Biol. Chem. 280, 16019-16029), treatment of cells with P44 peptide also showed a similar effect. The peptide could activate and stabilize p53 within the nucleus ( FIG. 4B ). However, both PS347A and SM peptide were unable to activate p53, as evident by almost negligible expression of p53 within the nucleus ( FIGS. 4C and G, respectively). On the other hand, p53 stabilization was observed in cells treated with PS348A, PS349A or PS350A ( FIGS. 4D , E and F, respectively) thereby confirming that the serine 347 residue of SMAR1 was indispensable for SMAR1-mediated p53 activation and hence stabilization.
Serine 347: Substrate for PKC family of proteins: Since the P44 peptide could result in a significant increase in P53 ser-15 phosphorylation, an in vitro kinase assay was performed to determine phosphorylation status of P44 peptide. Here the inventors observed that in the presence of whole cell extract from 293 cells enriched with cellular kinases, P44 but not the SM peptide, gets phosphorylated. There was about 6 to 7-fold increased γ-P 32 ATP incorporation in the wild-type peptide (P44) in comparison to its mutant counterpart (SM) ( FIG. 5 , dark bars 2 and 7, respectively). P44 phosphorylation was abolished as soon as the serine 347 residue was mutated to alanine (Ps347A) ( FIG. 5 , dark bar 3). However, phosphorylation was restored with other point mutated peptides (PS348A-PS350A) ( FIG. 5 , dark bars 4-6, respectively), strongly suggesting that the serine 347 residue of SMAR1 serves as the kinase-targeted molecule. Earlier, Inventors have reported that the protein kinase C (PKC) family of proteins is responsible for post-transcriptional modification of SMAR1 at its arginine-serine rich domain. To further analyse whether the serine 347 residue serves as a substrate motif, specifically for PKC, whole cell extract froth staurosporine (STS) (a PKC inhibitor) treated 293 cells was used for performing in vitro phosphorylation assays with various TAT-SMAR1 peptides. As expected, due to inhibition of PKC, cellular extracts prepared post STS-treatment failed to phosphorylate P44 peptide along with PS348A, PS349A and PS350A peptides ( FIG. 5 , light bars 2, 4-6, respectively). On the other hand, in case of PS347A and SM peptides, there was no difference in their phosphorylation status with or without STS treatment ( FIG. 5 , light and dark bars 3 and 7, respectively); thereby confirming that serine 347 residue of SMAR1 serves as the substrate for PKC family.
P44 peptide: A potent tumor regressor: To test whether the differences in SMAR1 derived peptide-induced activation of p53 translated to differences in drug sensitivity in vivo, B16F1 mouse melanoma cells were subcutaneously grafted into athymic nude mice, and tumor growth together with therapeutic sensitivity was monitored. Once the tumor nodule was established into the mouse, P44 peptide was injected in the tumor localized areas at a physiological dose of 200 μg/mouse thrice a week. The treatment was continued for 4 weeks. In a parallel experiment, either TAT PTD or TAT-SMAR1 RS mutant peptide, SM ( FIGS. 6A and B, respectively) was injected in tumor bearing mice to be used as control. Interestingly, there was a marked difference in the xenograft's response to the P44 peptide treatment. Almost 5-7 fold regression in tumor was observed in the mice injected with P44 peptide ( FIG. 6C ) compared to either TAT-injected or SM injected mice.
FIG. 6D-F corresponds to the magnified tumor images of FIG. 6A-C , respectively. After excision, the tumor weight was found to be 0.2 g-0.8 g for mice treated with the P44 peptide which was significantly less when compared to the mice treated with either the TAT PTD (1.5-3 G) or SM peptide (1.2-2.5 g) ( FIG. 6G ). Thus, P44 peptide mimics the function of full-length SMAR1 in drastically reducing the tumor growth.
Histopathological changes in the subcutaneous tumors: To analyze the tumor vasculature of TAT PTD, SM treated and P44 treated mice, the tumor sections were stained with HE. Tumors from TAT PTD (data no shown) and SM treated mice exhibited poorly organized vascular architecture and compressed blood vessels due to extensive cell proliferation ( FIG. 7A , lower panel). Contrarily, P44 treated tumors showed intact vasculature wherein the RBCs within the vessels were observed in healthy condition ( FIG. 7A , upper panel). In SM treated tumors, due to compressed vessels, the shape of RBCs were also distorted ( FIG. 7A , lower right panel, arrow marked). Inventors further observed that the inter-vessel distance in P44 treated tumors were significantly less compared to SM-treated tumors ( FIG. 7A , upper and lower left panels, respectively). The presence of hypoxic cells is a hallmark of cancer (Brown, J. M., and Wilson, W. R. (2004) Nat. Rev. Cancer 4, 437-447; Minchinton, A. I., and Tannock, I. F. (2006) Nat. Rev. Cancer 6, 583-592). Cellular responses to hypoxia are triggered by the hypoxia inducible factor-1 alpha (HIF-1α) that is known to restore tissue homeostasis in hypoxic conditions (Semenza, G. L. (2000) Genes Dev. 14, 1983-1991). To determine the status of HIF-1α expression, immunohistochemical analysis was performed on tumor sections obtained from SM and P44 treated mice by using antibody against HIF-1 α. Compared to P44 tumor sections, SM sections demonstrated increased HIF-1 α expression ( FIG. 7B ) thereby resulting into proliferation of tumor cells even under hypoxic conditions. All these observations implicate the significance of P44 peptide in restoring tissue architecture in tumor cells and thus potentiates its role as a tumor regressor.
Interest in peptides and proteins is becoming increasingly important, not only as molecular tools for the understanding of protein-protein interactions, but also as therapeutic compounds. Several oligopeptides such as p53 carboxyl terminal peptide, BH3 domain of Bak, p21WAF1-, p16INK4A-, Sos- and c-Myc derived peptide have been developed as a cargo and proved to function against cancer cells. In vitro studies involving systematic screening of panels of human-tumor derived cell lines for sensitivity to therapeutic agents has revealed associations with p53 status and drug sensitivity. Recently, inventors identified the arginine-serine (RS) rich domain as the minimal core region of SMAR1 that is responsible for activating p53-mediated pathway. In the present study, inventors investigated the antitumorigenic activity of a 33 amino-acid peptide sequence corresponding to the RS domain of SMAR1. The peptide was conjugated to protein transduction domain (PTD) of HIV-1 Tat protein, (TAT-SMAR1 WT peptide; p44) as PTD-TAT protein has been known to deliver bioactive peptides into tissues and across the blood-brain barrier. We found that almost 100% of cells were efficiently transduced by various SMAR1-derived peptides as observed through confocal imaging. All the chimeric TAT-SMAR1 derived peptides demonstrated efficient nuclear compartmentalization irrespective of the point mutations (PS347A-PS350A and SM) in the wild type SMAR1 peptide (P44), thereby suggesting that TAT PTD fusion with the SMAR1 peptide worked as an efficient peptide-delivery system. The P44 minimal peptide sequence of SMAR1 retained the functional activity of the full-length SMAR1 as it was capable of activating p53 as well as retaining into the nucleus. Accumulation of p53 in the nucleus resulted into arrest of the cell cycle at G2/M phase, which is in accord with the known growth inhibitory properties of high levels of wild-type p53.
Interestingly, the microarray data also demonstrated down regulation of important cell cycle regulatory proteins. Genes involved in regulating mitosis, MAPK signaling and cell cycle checkpoints showed significant decreased expression upon P44 treatment, emphasizing its role as a cell cycle modulator. Furthermore, reduced expression of proteins involved in ubiquitin-proteasome signaling may serve as an alternative mechanism to support P44-mediated stabilization and increased nuclear retention of p53.
Recent studies have proposed that phosphorylation of N-terminal amino acids of p53 contribute to its regulation by affecting the binding of co-activators and the negative regulator MDM2. These studies emphasize the significance of phosphorylation at serine 15, serine 20 or serine 37 residue of p53 in maintaining protein stability as well as transactivation properties. Interestingly, P44 peptide alone could mediate the phosphorylation of p53 at its serine 15 residue and in effect result in upregulation of the phospho-cdc2, indicating that p53-modulating activity of full-length SMAR1 resided entirely within the P44 peptide. Results obtained from luciferase reporter assays further confirmed the bioactivity of the SMAR1 derived peptide and demonstrated that it followed a p53-dependent p21-growth suppression pathway. We have previously demonstrated that the substrate motif for protein kinase C family of serine threonine kinases resides within the arginine-serine rich domain of SMAR1. In this study, by using various point-mutated peptides of P44, it was demonstrated that serine 347 residue of SMAR1 is critical for its function and upon mutation to alanine (in case of PS347A as well as SM-mutant peptide), results in loss of its phosphorylation and hence reduced functional activity. However, staurosporine treatment resulted in a complete inhibition of phosphorylation of peptides containing intact serine 347 residue. Peptides where serine 347 was replaced with alanine (that included PS347A as well as SM) demonstrated no difference in their phosphorylation status irrespective of the presence or absence of STS, thereby emphasizing the importance of serine 347 in phosphorylation of P44 peptide. Moreover, in SM peptide wherein serine 347-350 residues were mutated to alanine, we observed further reduction in its phosphorylation compared to PS347A peptide, thus suggesting the significance of other serine, residues (348-350) in the phosphorylation of P44 peptide.
In this study using xenograft tumor nude mice model, it was demonstrated that the TAT-SMAR1 WT (P44) peptide strongly regressed tumors and the anti-tumorigenic activity of the P44 peptide was significantly reduced when the serine residues were mutated to alanine [TAT-SMAR1 RS mutant (SM)]. Histopathological analysis of tumor section from control tumors (TAT PTD and SM-treated) revealed increased cellular proliferation resulting into blood vessel condensation. However, there was pronounced destruction of the tumor architecture upon treatment with P44 peptide. It prevented vascular damage and maintained cellular integrity. Protection against hypoxia in solid tumours is an important step in tumour development and progression. A multifaceted adaptive response is triggered by hypoxia, which is primarily mediated by hypoxia inducible factor-1 (HIF-1) system, which plays a crucial role especially in angiogenesis and carcinogenesis. Alteration and overexpression of HIF-1α has been detected in a variety of solid tumours, including breast, lung, ovarian and oral cancer with varying staining patterns. We also observed an increased expression of HIF-1α in cells treated with either TAT PTD or SM peptide compared to those treated with P44 peptide. Thus, P44 peptide restores normoxia in tumor cells, which may be responsible for decreasing HIF-1α expression, even though the mechanism is yet not clear.
DETAILED DESCRIPTION OF THE FIGURES
FIG. 1 . Cellular uptake of TAT conjugated SMAR1 derived peptides in HEK 293 cells. 2×10 5 cells were incubated with 10 μM concentration of peptide for 6 h at 37° C. Peptides were labeled with the TRITC-fluorochrome as described under “Experimental Procedures”. A, A cartoon representation of the TAT PTD-SMAR1 chimeric peptide depicting its various domains. FIG. B corresponds to unconjugated SMAR1 peptide; C, TAT-SMAR1 WT (P44) peptide and D-H, various P44 serine mutant peptides (D, SM;E, PS347A; F, PA348A; G, PS349A; and H, PS350A) at a concentration of 10 μM. FIGS. I-L demonstrate dose-response study of TRITC-labeled P44 peptide. 2×10 5 293 cells were incubated with varying concentration of peptide for 6 h at 37° C. FIG. I, 100 nM; J, 1 μM; L, 50 μM of the peptide concentration. Left panel shows the nuclear staining with DAPI, middle panel corresponds to TRITC fluorescence and the right panel shows a merged image. All images were recorded with the same camera acquisition parameters.
FIG. 2 . P44 peptide activates the p53-driven p21 gene expression in reporter assays. p21 promoter activity was checked in both HEK 293 (p53 +/+ ) (A) and K562 (P53 −/− ) cells (B). Cells were transfected with either pG13 CAT reporter plasmid, a p53-driven p21 promoter, in HEK 293 cells or cotransfected with wild-type (wt) p53 in K562 cells. After 24 h post-transfection, cells were treated for 12 h with 10 μM concentration of various TAT-SMAR1 chimeric peptides. Y axis represents the fold luciferase activity (mean±SD of three independent experiments).
FIG. 3 . P44 peptide activates p53-mediated cell cycle pathway. A, HEK 293 cells were seeded at a density of 5×10 5 and after 24 h, was incubated with increasing concentrations of the TAT-SMAR1 WT (P44) peptide. Protein lysates were prepared and then immunoblotted with antibodies to total p53, phospho serine-15. B, The same set of experiment was repeated with TAT PTD peptide representing the PTD carrier sequence alone and immunoblotted with phospho serine-15, in comparison of P44 treated cells. C, The status of phospho cdc-2 was further analyzed in P44 peptide treated cells. Total ERIC was used as an internal control. D, The same set of experiments were again repeated using TAT-SMAR1 RS mutant (SM) peptide and whole cell lysates were probed for phospho p53 serine-15 and pcdc-2 antibodies. Action was used as a loading control.
FIG. 4 . Serine 347 residue of SMAR1 mediates p53 activation and stabilization. A, HEK 293 cells were cultured at a density of 5×10 5 cells and 24 h later treated with 10 μM concentration of either the P44 or various serine-mutant peptides (PS347A, PS348A, PS349A, PS350A and RS mutant; SM). After 12 h of treatment, protein lysates were prepared and immunoblotted using pSer-15 p53 and pcdc-2 antibodies. Actin was used as the loading control. B, Peptides P44 (panel B), PS347A (panel C), PS348A (panel D), PS349A (panel E), PS350A (panel F) and SM (panel G) were incubated at a final concentration of 10 μM with HEK 293 cells for 12 h before indirect immunofluorescence detection with a primary antibody against p53 protein and a secondary fluorescein-conjugated anti-mouse IgG.
FIG. 5 . Serine 347 residue of SMART is phosphorylated by protein kinase C. One microgram of various TAT-SMAR1 derived peptides (P44, PS347A, PS348A, PS349A, PS350A and SM) were subjected to an in vitro phosphorylation assay using whole cellular extract from HEK 293 cells and then the γ-P 32 ATP incorporation was detected as counts per minute by the scintillation, counter. Cells were either kept untreated (dark bars) or were treated with the PKC inhibitor, staurosporine at a final concentration of 20 nM (light bars).
FIG. 6 . Tumor regression by TAT-SMAR1 WT peptide. A, Nude mice were allowed to develop tumors by subcutaneously injecting B 16F1 mouse melanoma cells. Mice with size-matched tumors were then randomized into three treatment groups (five animals per group); TAT PTD alone (panel A), TAT-SMART RS mutant (SM) (panel B) and TAT-SMAR1 WT (P44) (panel C). Panels D, E and F correspond to the magnified images of panels A, B and C, respectively. Mice were treated with either of the peptides at a dose of 200 μg/mice/thrice a week for consecutive 4 weeks. The tumors were then weighed and plotted for each mouse in all the treatment groups (panel G).
FIG. 7 . Histopathological changes in B16F1-induced tumors. A, Hematoxylin and eosin staining of tumor sections excised from mice treated with either P44 (upper panel) or SM (lower panel) peptide. Vascular damage was observed in tumors treated with the mutant peptide; SM (arrows, lower right panel) whereas the blood vessels were relatively undamaged in the mice treated with the wild type peptide; P44 (arrows, upper right panel). The images have been recorded at 20× and 40×. B, Immunohistochemistry of paraffin embedded tumor sections from P44 treated as well as, SM treated mice. After antigen unmasking, sections were stained with HIF-1α antibody (middle panel) and detected using Cy-3 conjugated mouse immunoglobulin. Sections were counterstained with DAP1 for nuclear localization (left panel). Right panel corresponds to the merged image.
Table 1. Amino acid sequences of protein transduction domain and SMAR1 derived chimeric peptide conjugates. The chimeric peptides have SEQ ID NOs: 1-14, reading from the top to the bottom of the Table.
EXAMPLES
Peptide synthesis: The chimeric TAT-SMAR1 peptides [SMAR1 WT. (P44); SMAR1 RS mutant (SM); and other serine-mutant peptides (PS347A, PS348A, PS349A, and PS350A)] (Table 1) were custom synthesized from GenoMachanix, L.L.C. U.S.A. Peptides were resuspended in deionized water and stored at −20° C. until further use.
Labeling of SMAR1 peptides with TRITC fluorochrome: Twenty five microgram of the TAT-SMAR1 derived peptides dissolved in PBS was mixed with equimolar amount of 0.1M di-sodium tetraborate buffer, pH 9.0. This mixture was then incubated for 45 min in the dark at room temperature with 10 μg TRITC (5 mg/ml stock solution) dissolved in DMSO. The reaction was stopped by adding of 1M Tris glycine. The peptide-TRITC conjugate was loaded on the top of a PD-10 column (BioRad) that was previously equilibrated with PBC. The column was eluted with 10 ml of PBS and the first few fractions of the fluorescent material were collected. The LTV absorbance for the labeled peptide was measured at 550 nm (TRITC) and 280 nm (peptide).
Western blotting and immunoprecipitation: HEK 293 cells (5×10 5 ) were cultured as exponentially growing sub confluent monolayer on 35 mm plates in DMEM medium (Invitrogen) supplemented with 10% (v/v) fetal calf serum. After 24 h, cells were treated with varying concentrations of either of the TAT-SMAR1 derived peptides (Table 1). Cells were then incubated at 37° C. for 12 h followed by preparation of whole cell protein extracts. For Western blotting, equal amount of the protein was separated on 10% SDS PAGE and subsequently transferred to PVDF membrane (Amersham). It was finally probed with the following antibodies; anti-p53 (DO-1); anti-phospho p53 Ser-15 and anti pcdc-2. The detailed protocol for the same is discussed in our earlier publication (30).
Immunocytochemistry and confocal imaging: For direct detection of TRITC-labeled peptides, HEK 293 cells were plated directly on a glass coverslip and cultured overnight prior to their treatment to TRITC-conjugated various TAT-SMAR1 derived peptides. After 12 h incubation, three washings with cold PBS were given and the cells fixed with 3.7% paraformaldehyde before being mounted in PBS/Glycerol (1:1) containing antifading agent. For indirect immunodetection, 2×10 5 HEK 293 cells were plated and cultured overnight in 35 mm plates on glass coverslips. The cell monolayer was then treated with either of the various TAT SMAR1 derived peptides, dissolved directly in complete DMEM medium at the appropriate concentration (final concentration 10 μM). After 12 h incubation, cells were washed twice with cold PBS and fixed with 3.7% paraformaldehyde. Subsequently, fixed cells were stained for total p53 using anti-p53 (DO-1) (SantaCruz) for an hour at room temperature.
For detection, cells were incubated with a secondary-antibody mix containing FITC-conjugated anti-mouse IgG antibodies (Sigma) for 1 h at RT. Slides were then mounted in antifade mounting medium (Dako) and analyzed with a confocal laser scanning microscope (CLSM 510, version 2.01; Zeiss, Thornwood, N.Y.).
Cell Cycle analysis by Flow Cytometry: HEK 293 cells were transiently transfected with GFP-tagged SMART truncations (160-288 aa and 288-350 aa). After 48 h of transfection, the cells were trypsinized, washed with 1× phosphate-buffered saline and fixed in 70% ice-cold ethanol. After incubating at −20° C. for 20 min, the cells were spun at 1000 rpm for 5 min at room temperature. The cells were washed with PBS, treated with RNase A (75 U/ml) for 30 min at 37° C., washed again in PBS and resuspended in PBS containing 50 μg/ml Propidium Iodide. After staining the cells with PI, they were analyzed by FACS Vantage (Becton Dickinson) using the cell quest program (Verity Software) for cell cycle profiles.
In vitro phosphorylation assay: HEK 293 cells were seeded at a density of 5×10 5 per well and harvested after 24 h either for preparation of whole cell extract or treatment with 20 nM concentration of staurosporine (a PKC inhibitor) (31, 32). After 48 h of treatment, lysates were prepared using the kinase lysisi buffer (20 mM Tris, pH 8.0, 500 mM NaCl, 1 mM EDTA, 1 mM EGTA, 10 mM β-Glycerophosphate, 10 mM NaF, 10 mM PNPP, 30 mM Na 3 VO 4 , 1 mM Benzamide, 2 mM PMSF, 1 mM DTT, 0.25% NP-40 and protease inhibitor cocktail). After incubating on ice for 20 min, lysates were spun at 14,000 rpm for 10 min. For the kinase reaction, various TAT-SMAR1 derived peptides (Table-1), were incubated with 2 μg of either the whole cell kinase extract (WCK) or with staurosporine-treated kinase extracts along with 10 μM ATP (γ-P 32 ), 2 mM MgCl 2 and the kinase assay buffer (20 mM Tris, 2 mM MgCl 2 , 2 mM CaCl 2 , 10 mM β-Glycerophosphate, 10 mM NaF, 10 mM PNPP, 30 mM Na 3 VO 4 , 1 mM Benzamide, 2 mM PMSF, 1 mM DTT and protease inhibitor cocktail). The reaction mixture was incubated at 30° C. for 30 min and them reaction was stopped by adding 0.5 mM EDTA. BSA was added at a final concentration of 1 mg/ml along with 10% TCA. TCA-precipitated peptides were then resuspended in scintillation fluid and checked for P 32 incorporation.
Luciferase reporter assay: HEK 293 (p53 +/+ ) and K562 (p53 −/− ) cells were grown in DMEM supplemented with 10% FBS in the presence of 5% CO 2 at 37° C., a total number of 1×10 6 , cells were plated on a 6-well plate. After 24 h, cells were transiently transfected using lipofectamine-2000 with either 1 μg of p21 expression plasmid having luciferase reporter gene or 5 μg p21 luciferase along with wt p53 construct in K562 cell line. Two micrograms of pRL-CMV (Renilla luciferase reporter plasmid) was included in all transfections to normalize the transfection efficiency. Thirty six hours post-transfection, cells were treated with 10 μM of either P44 peptide or its various mutants. The cells were harvested 12 h post-treatment, washed with PBS and lysed in 1× Passive lysis buffer (Promega). After three freeze-thaw cycles, cells were spun at 10,000 rpm at 4° C. for 20 min. The supernatants were collected and protein concentrations were estimated spectrophotometrically using Bradford reagent as (BioRad, CA). According to the manufacturer's instructions, luciferase activity was assessed using the dual luciferase assay reporter kit (Promega). The luciferase activity was measured by using Fluoroskan Ascent Luminometer (Labsystems). For all the luciferase assays, the data shown are the mean+SD of three independent experiments.
Animal model for tumorgenesis: B16F1 mouse melanoma cells in the exponential growth phase were trypsinized (Invitrogen) and washed twice with PBS. Cell number and viability was assessed and cell cultures with viability >90% were used. Tumors were then established in nude mice by subcutaneous injection of 2×10 6 B16F1 cells. Five mice were used in each set of experiments. The mice were maintained under pathogen-free conditions. When the subcutaneous tumor was clearly visible, the TAT-SMAR1 WT (P44) peptide treatment was started. The P44 peptide was subcutaneously injected proximal to the tumor sites at a dose of 200 μg/mouse thrice a week. The treatment was administered for 4 weeks. For control treatment, TAT PTD alone and TAT SMAR1 RS mutant peptide (SM) were injected in the same manner as the P44 peptide.
Immunohistochemical staining of tumor sections: Tumor sections in paraffin-embedded blocks were transferred to poly-L-lysine coated glass slides and air-dried overnight at 37° C. They were dewaxed in xylene (three changes) and dehydrated in graded series of decreasing ethanol concentrations. After deparaffinization and rehydration, antigen retrieval was performed by immersing the slides in 10 mM sodium citrate buffer (pH 6.0) and subjected to microwave irradiation for 10 min. After antigen unmasking, a cooling-off period of 30 minutes preceded the incubation of the primary antibody (anti-HIF-1α; 1/100 dilution; SantaCruz). Thereafter, detected using cy-3 fluorescence labeled secondary antibody. All sections were counterstained with HE and dehydrated in alcohol and xylene. Tissue samples with non-immune serum served as negative controls.
Sequence (N—C)
Peptide
TAT
YGRKKRRQRRR
TAT-
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPSSSSYSAS E TM
SMAR1WT
(P44)
TAT-
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPAAAAYSAS E TM
SMAR1 RS
mutant
(SM)
Point
mutants of
P44
PS347A
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPASSSYSAS E TM
PS348A
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPSASSYSAS E TM
PS349A
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPSSASYSAS E TM
PS350A
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPSSSAYSAS E TM
PS1A
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPSAAAYSAS E TM
PS2A
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPSSAAYSAS E TM
PS1T
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPTAAAYSAS E TM
PS2T
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPTSSSYSAS E TM
PS3T
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPTTTTYSAS E TM
PS5A
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPAAAAYAAS E TM
PS5T
YGRKKRRQRRRTAW RRKQRGQSLAVKSFSRRTPAAAAYTAS E TM
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Chimeric tumor suppressor activating peptides derived from matrix attachment region binding protein (MARBP) SMARI unique in their sequence comprising a arginine rich motif flanked by serine residues wherein from the stretch of four consecutive serine residues the first serine residue gets phosphorylated by the protein kinase C family of serine threonine kinases being indispensable for its functionality, the phosphorylation being directly correlated to the phosphorylation of p53 at serine 15 residue thereby stabilizing it, wherein the peptide activates p53 by modifying it post translationally which allow phosphorylation and translocation of p53 to the nucleus.
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BACKGROUND OF THE INVENTION
[0001] The present invention relates to a virtual computer system, and particularly to a virtual computer system and a control method of migrating a logical partition by which, when a failure occurs in the logical partition on a physical computer, a substitute for the logical partition is generated on another physical computer to migrate a process of the logical partition.
[0002] There has been put to practical use a virtual computer system in which plural logical computers or logical partitions (hereinafter, referred to as LPARs) are established on a physical computer and OSs (operating systems) are allowed to operate on the respective logical computers, thereby allowing the unique OSs to operate on the plural logical computers. Further, as a recent example of the virtual computer system, the virtual computer system in which a logical FC (Fibre Channel) extension board or a logical FC port is mounted to each virtual computer is used under an SAN (Storage Area Network) environment including an RAID (Redundant Array of Inexpensive Disks) apparatus.
[0003] In the computer system to realize booting under the SAN environment, in order to protect data of logical units in the RAID apparatus in which OSs are installed, a security function by which an access is permitted only from the respective computers is realized by the RAID apparatus. The security function generally utilizes a method in which, by using unique IDs (World Wide Names) assigned to the FC ports mounted on the respective computers, the logical units having the OSs installed are associated with the unique IDs (World Wide Names) assigned to the FC ports provided for the computers and an access is permitted only from the FC ports having the IDs (World Wide Names). Further, the IDs (World Wide Names) unique to the apparatuses are recorded in software including OSs in some cases.
[0004] In a redundant configuration of the computer system to perform booting from the SAN, the unique IDs (World Wide Names) assigned to the FC ports are different depending on an actually-used computer and a standby computer. Accordingly, when the actually-used computer is migrated to the standby computer, a software image including an OS cannot be used as it is, and it is necessary to change setting of the security function on the RAID apparatus side by SAN management software or a system administrator. The setting change is required not only between the physical computers such as the actually-used computer and the standby computer, but also between the LPARs in the virtual computer system. Specifically, even when plural LPARs are allowed to operate on the physical computers in the virtual computer system and an actually-used LPAR is migrated to a standby LPAR, it is necessary to change the setting of the security function on the RAID apparatus side due to difference of the unique IDs (World Wide Names) assigned to the logical FC ports of the respective LPARs.
[0005] For example, JP-A 2005-327279 and H10-283210 disclose a technique in which, in a virtual computer system where LPARs can be established on plural physical computers, configuration information of the LPAR is migrated from the LPAR of one physical computer to another physical computer to take over its operation.
SUMMARY OF THE INVENTION
[0006] JP-A 2005-327279 and H10-283210 do not disclose migrating of the LPAR by which when a failure occurs in the LPAR of the physical computer, another LPAR generated in another physical computer is used as a standby LPAR.
[0007] Further, JP-A 2005-327279 and H10-283210 do not disclose taking over of the unique ID (World Wide Name) assigned to the logical FC port of the LPAR because the setting change of the security function on the RAID apparatus side is unnecessary when one LPAR is migrated to another in the virtual computer system under the SAN environment.
[0008] An object of the present invention is to provide a virtual computer system in which when a failure occurs in an LPAR on a physical computer under an SAN environment, a destination LPAR is set in another physical computer to enable migrating of the LPAR without necessity of setting change of a security function on the RAID apparatus side.
[0009] According to the present invention, there is preferably provided a virtual computer system having plural physical computers including first and second physical computers and a management apparatus that is connected to the plural physical computers via a network to manage the physical computers and logical partitions, and allows OSs to operate by generating the logical partitions on the physical computers, wherein the first physical computer includes: failure detection means for detecting that a failure occurs in the first physical computer or a first logical partition formed in the first physical computer; and first management means for managing hardware configuration information of the first physical computer and unique configuration information assigned to the first logical partition, the management apparatus includes: means for accepting notification of the failure occurrence from the failure detection means to receive the hardware configuration information and the unique configuration information from the first management means; and means for determining the substitute second physical computer to transmit the hardware configuration information and the unique configuration information to the second physical computer, and the second physical computer includes: means for receiving the hardware configuration information and the unique configuration information transmitted from the management apparatus; means for determining whether or not a second logical partition can be generated on the second physical computer on the basis of the hardware configuration information and the unique configuration information; and means for generating the second logical partition on the basis of the unique configuration information when the determination means determines that the second logical partition can be generated.
[0010] According to the present invention, when a failure occurs in the LPAR on the physical computer under the SAN environment, the destination LPAR is set in another physical computer so as to enable migrating of the LPAR without necessity of setting change of the security function on the RAID apparatus side. Further, configuration information and the like of the original LPAR are migrated to the destination LPAR under the control of the management server, so that even when a failure occurs in the original physical computer, migrating of the LPAR can be realized.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a view showing a configuration of a computer system according to an embodiment;
[0012] FIG. 2 is a flowchart showing a process performed when a failure occurs;
[0013] FIG. 3 is a flowchart showing a process performed when a failure occurs;
[0014] FIG. 4 is a flowchart showing a process performed by a management server when a failure occurs;
[0015] FIG. 5 is a flowchart showing a process performed by the management server when a failure occurs;
[0016] FIG. 6 is a flowchart showing a process performed by a hypervisor when a failure occurs;
[0017] FIG. 7 is a flowchart showing a process of a command in a Hypervisor-Agt;
[0018] FIG. 8 is a flowchart showing a process of a command in the Hypervisor-Agt;
[0019] FIG. 9 is a flowchart showing a transmission process performed by the Hypervisor-Agt;
[0020] FIG. 10 is a flowchart showing a transmission process performed by the Hypervisor-Agt;
[0021] FIG. 11 is a view showing contents of hardware configuration information 1101 of a server;
[0022] FIG. 12 is a view showing contents of hypervisor configuration information 1111 ; and
[0023] FIG. 13 is a view showing contents of management information 107 of the server.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0024] Hereinafter, an embodiment will be described with reference to the drawings.
[0025] Referring to FIG. 1 , a computer system according to an embodiment has a configuration of a blade server in which plural server modules (hereinafter, simply referred to as servers) 111 and 112 can be mounted in a server chassis 105 . A service processor (SVP) 106 is mounted in the server chassis 105 .
[0026] The servers 111 and 112 are connected to a management server 101 through NICs (Network Interface Cards) 122 and 132 via a network SW 103 , respectively, and connected to a storage apparatus 137 through FC-HBAs (Fibre Channel Host Bus Adapters) 121 and 131 via a fibre channel switch (FC-SW) 135 , respectively.
[0027] The servers 111 and 112 basically have the same configuration and include BMCs (Base Management Controllers) 120 and 130 , the FC-HBAs 121 and 131 , and the NICs 122 and 132 , respectively. Each of hypervisors 117 and 127 is a virtual mechanism by which physically one server logically appears to be plural servers.
[0028] In the server 111 , two LPARs 113 and 114 simulated on the hypervisor 117 are established and operated. Each of Hypervisor-Agts 119 and 129 in the hypervisors 117 and 127 is an agent which detects a failure of the LPARs and notifies the management server 101 of the failure.
[0029] An LPAR 123 is operated in the server 112 in the embodiment, and a destination LPAR 4 ( 124 ) of the LPAR 2 ( 114 ) in the server 111 is set later.
[0030] In order to establish communications, each of the FC-HBAs 121 and 131 has one WWN for each FC connection port as an HBA address. The LPARs 113 and 114 are provided with logical HBA ports 115 and 116 , respectively, and the ports are given unique WWNs (World Wide Names) such as vfcWWN 1 ( 115 ) and vfcWWN 2 ( 116 ), respectively. Each logical HBA also has the same WWN as the physical HBA. It should be noted that the LPAR 3 ( 123 ) in the server 112 is also similarly given a unique WWN.
[0031] The storage apparatus 137 has plural disk units 138 to 140 called LUs (logical units) which are logically specified. Connection information indicating association of the LUs with the servers is managed by a controller in the storage apparatus 137 . For example, the LU 10 ( 138 ) is connected to the LPAR 113 having the vfcWWN 1 ( 115 ) as the WWN, and the LU 11 ( 139 ) is connected to the LPAR 114 having the vfcWWN 2 ( 116 ) as the WWN. A function for setting the connection relation is called an LUN security setting function.
[0032] The SPV 106 manages all the servers in the server chassis, and performs power source control and a failure process of the servers. In order to manage the servers, hardware configuration information 1101 (see FIG. 11 ) of the server and hypervisor configuration information 1111 (see FIG. 12 ) are stored into a nonvolatile memory (not shown) in the SVP for management. The configuration information 1101 and 1111 are managed for each server, and the SVP has two-screen configuration information 108 - 1 and 108 - 2 corresponding to the servers 111 and 112 , respectively, in the example illustrated in FIG. 1 . Further, the hypervisor configuration information 1111 includes information corresponding to the hypervisors 117 and 127 of the servers 111 and 112 .
[0033] The management server 101 manages the servers 111 and 112 and the LPARs formed in the servers. Therefore, management information 107 (see FIG. 13 ) of the servers is stored into a memory (not shown) for management. In the embodiment, a function of managing migrating of the LPAR is also provided.
[0034] Next, contents of the respective management information will be described with reference to FIGS. 11 to 13 .
[0035] As shown in FIG. 11 , the hardware configuration information (occasionally referred to as server module/hardware configuration information) 1101 of the server holds physical server information such as boot setting information 1102 , HBA-BIOS information 1103 , addWWN information 1104 , OS-type information of physical server 1105 , designation of disabling hyper threading 1106 , an IP address of hypervisor stored by SVP 1107 , and an architecture 1108 . The hardware configuration information 1101 is present for each server module (partition).
[0036] As shown in FIG. 12 , the hypervisor configuration information 1111 is information managed for each LPAR in the partitions, and is present for each of the LPARs 113 and 114 (illustrated by using 1111 - 1 and 1111 - 2 ). Each hypervisor configuration information 1111 holds information such as vfcWWN information ( 1112 - 1 ), Active/NonActive ( 1113 - 1 ) indicating whether or not the LPAR is being active, CPU information ( 1114 - 1 ) including the number of CPUs and the like, a memory capacity ( 1115 - 1 ), and an I/O configuration ( 1116 - 1 ) including the HBA, NIC and the like.
[0037] Although the hardware configuration information 1101 of the server and the hypervisor configuration information 1111 are set and managed by the SVP 106 , these pieces of information are held by each hypervisor operated on the servers.
[0038] As shown in FIG. 13 , the management information (occasionally referred to as server module management information) 107 of the servers managed by the management server 101 holds information such as a server module number 1201 , an architecture type of hardware 1202 , a mounted-memory capacity 1203 , a total memory utilization of active LPARs 1204 , a memory free space 1205 , a mounted-CPU performance 1206 , total performances of assigned-CPUs 1207 , an available CPU performance 1208 , the number of available NICs 1209 , and the number of available HBAs 1210 .
[0039] According to the embodiment, when a failure occurs in the LPAR of the server 111 , the management server 101 that receives the failure notification sets the destination LPAR 4 ( 124 ) in the server 112 and controls to allow the LPAR 4 ( 124 ) to take over the configuration information unique to the LPAR where the failure occurs.
[0040] Hereinafter, a setting process of the destination LPAR and a takeover process of the configuration information unique to the LPAR when a failure occurs in the LPAR in the server 111 will be described in detail with reference to FIGS. 2 and 3 . The example illustrated in FIGS. 2 and 3 shows processing operations performed by the management server 101 , the hypervisor 117 of the server 111 , and the hypervisor 127 of the server module 112 when a failure occurs in the LPAR 2 ( 114 ) of the server 111 .
[0041] When a failure occurs in the LPAR 2 ( 114 ) and the hypervisor 117 operated in the server 111 detects the failure (S 201 ), the hypervisor 117 transmits a failure notification (Hypervisor-Agt alert) to the management server 101 (S 202 ). The management server 101 transmits a deactivate command so as to deactivate the LPAR 2 where the failure occurs (S 203 ). After receiving the LPAR deactivate command, the hypervisor 117 performs deactivation (a deactivate process) of the LPAR 2 (S 205 ). When the deactivate process is completed, the hypervisor 117 transmits the Hypervisor-Agt alert to the management server 101 to notify the same of the completion of deactivate (S 206 ).
[0042] The management server 101 which receives the Hypervisor-Agt alert displays a deactivate status of the LPAR where the failure occurs on a display unit as management information (S 207 ), and transmits a configuration information reading command of the LPAR 2 (S 208 ).
[0043] The hypervisor 117 which receives the command transmits the server module/hardware configuration information and the hypervisor configuration information of the LPAR 2 held by the hypervisor 117 to the management server 101 (S 209 ).
[0044] When completing the reception of the data, the management server 101 displays the completion of reception (S 210 ). Thereafter, the management server 101 determines a destination server module (S 301 ). For example, the management server 101 instructs the hypervisor 127 , which is supposed to generate the LPAR on the destination server module 112 , to receive the server module/hardware configuration information of the server module 111 where the failure occurs and the hypervisor configuration information of the LPAR 2 (S 302 ).
[0045] When receiving the configuration information relating to the LPAR 2 where the failure occurs (S 303 ), the hypervisor 127 determines whether or not the LPAR can be generated in the destination server module on the basis of the configuration information (S 305 ). The determination will be described later in detail. If the result of the determination satisfies predetermined conditions, the LPAR which takes over the configuration information relating to the LPAR 2 of the original server is generated in the destination server 112 (S 306 ). In this example, the LPAR 4 ( 124 ) serves as the LPAR of the destination server. When completing the generation of the LPAR 4 ( 124 ), the hypervisor 127 transmits the Hypervisor-Agt alert and notifies the completion of generation of the LPAR (S 307 ).
[0046] When receiving the Hypervisor-Agt alert, the management server 101 transmits an activate command to the hypervisor 127 so as to activate the generated LPAR 4 (S 308 ). The hypervisor 127 which receives the activate command activates the generated LPAR 124 (S 309 ). Then, the hypervisor 127 transmits the Hypervisor-Agt alert and notifies the completion of activate of the LPAR 124 (S 310 ). The management server 101 which receives the Hypervisor-Agt alert displays an activate status of the LPAR 124 on the display unit (S 311 ).
[0047] Next, a process performed by the management server 101 when a failure occurs in the LPAR 2 ( 114 ) will be described with reference to FIGS. 4 and 5 .
[0048] When receiving the Hypervisor-Agt alert which notifies that the failure occurs in the LPAR 2 from the hypervisor 117 , the management server 101 starts a process at the time of detecting the LPAR failure (S 401 ).
[0049] First of all, the management server 101 transmits a deactivate command to the hypervisor 117 of the server module 111 in which the LPAR 2 where the failure occurs is operated so as to deactivate the operation of the LPAR 2 (S 402 ). Thereafter, the management server 101 waits until the deactivate process of the LPAR 2 is completed (S 403 ). When the deactivate process is properly completed, the management server 101 updates a display table of the LPAR 2 to “deactivate status” (S 404 ). On the other hand, when the deactivate process is not properly completed, the management server 101 displays a cold standby failure (S 411 ), and terminates the process (S 412 ).
[0050] When the display table of the LPAR 2 is updated to “deactivate status” (S 404 ), the management server 101 transmits the configuration information reading command of the LPAR 2 (S 405 ). When receiving the configuration information of the LPAR 2 (S 406 ) and properly completing the reception (S 407 ), the management server 101 displays the completion of reception (S 408 ). On the other hand, when the reception is not properly completed, the management server 101 displays the cold standby failure (S 413 ) and terminates the process (S 414 ).
[0051] After the management server 101 properly completes the reception (S 407 ) and displays the completion of reception (S 408 ), the management server 101 computes an effective CPU performance of the LPAR 2 and an effective CPU performance of the server module other than one that generates the LPAR 2 .
[0052] Here, the effective CPU performance of the LPAR 2 is obtained by multiplying (the number of physical CPUs) by (a service ratio of the LPAR in the original server module). Further, the effective CPU performance of the server module other than one that generates the LPAR 2 is obtained by multiplying (the number of physical CPUs) by (100%−(service ratios of all LPARs that are being activated)).
[0053] Next, the management server 101 determines the conditions of the server module for LPAR generation by using the server module management information 107 of the management server 101 (S 410 ). The conditions include, for example, the following determinations such as (a) whether the server module having the same architecture as the LPAR 2 is present, (b) whether the server module having an available memory equal to or larger than that of the LPAR 2 is present, (c) whether the server module having an effective CPU performance equal to or higher than that of the LPAR 2 is present, and (d) whether the server module having available NICs and HBAs equal to or larger in number than those used by the LPAR 2 .
[0054] If these four conditions are all satisfied, the management server 101 selects one server module with the highest effective CPU performance as the destination server module among the server modules that satisfy the conditions (S 501 ). If any one of the four conditions is not satisfied, the management server 101 displays the cold standby failure (S 415 ) and terminates the process (S 416 ).
[0055] When the destination server module (the server module 112 in this example) which satisfies the four conditions is selected, the management server 101 transfers the configuration information relating to the LPAR 2 where the failure occurs to the hypervisor 127 of the destination server module 112 and instructs to generate the LPAR (S 502 ). The management server 101 transmits the data (configuration information relating to the LPAR 2 where the failure occurs) received from the hypervisor 117 of the server module 111 where the failure occurs to the hypervisor 127 (S 503 ). When the data transmission is properly completed (S 504 ), the management server 101 displays the completion of transmission (S 505 ). On the other hand, when the data transmission is not properly completed (S 504 ), the management server 101 displays the cold standby failure (S 511 ) and terminates the process (S 512 ).
[0056] Thereafter, the management sever 101 waits until the LPAR is generated in the destination server module 112 (S 506 ). The LPAR 4 to be generated has the same configuration as the LPAR 2 where the failure occurs. When the generation of the LPAR 4 is properly completed, the management server 101 transmits a command of activating the destination LPAR 4 ( 124 ) of the destination server module 112 (S 507 ). On the other hand, when the generation of the LPAR 4 is not properly completed, the management server 101 displays the cold standby failure (S 513 ) and terminates the process (S 514 ).
[0057] When the generation of the destination LPAR 4 ( 124 ) is properly completed and the activate command is transmitted (S 507 ), the management server 101 awaits completion of activating the destination LPAR 4 ( 124 ) (S 508 ). When the destination LPAR 4 is properly activated, the management server 101 updates the status of the destination LPAR 4 ( 124 ) to “activate status” (S 509 ), and terminates the process (S 510 ). On the other hand, when the destination LPAR 4 ( 124 ) is not properly activated, the management server 101 displays the cold standby failure (S 515 ) and terminates the process (S 516 ).
[0058] Due to the following reasons, the above-described control allows the destination LPAR 4 ( 124 ) to be activated as a substitute for the LPAR 2 ( 114 ) where the failure occurs. An access to the storage apparatus is controlled by using a WWN. The WWN is assigned to each port of the physical devices. However, the logical HBA is provided for each LPAR and the WWN is assigned to each port of the logical HBAs in the embodiment. The WWN of the logical HBA is hereinafter called vfcWWN. As described in FIG. 1 , the connection relation between the LUNs and WWNs is set by the LUN security function. Since the logical WWN is not distinguished from the physical WWN from the storage apparatus side, it is possible to manage the access right to the LU on an LPAR basis (when the vfcWWN is used, the WWN of the physical device is set so as not to be recognized from the storage apparatus). By booting the destination LPAR using the same vfcWWN as that used by the LPAR where the failure occurs, the same system as that in the original server can be started.
[0059] Next, a process performed by the hypervisor when a failure occurs in the LPAR 2 will be described with reference to FIG. 6 .
[0060] When a failure occurs in the LPAR 2 , the hypervisor 117 starts an LPAR failure detection process (S 601 ). In the failure detection process, the hypervisor 117 analyzes a factor of the failure occurrence to determine whether or not the factor is recoverable (S 602 ). If the result of the determination shows that the LPAR failure is caused by an unrecoverable factor, the hypervisor 117 requests transmission of the Hypervisor-Agt alert to notify the Hypervisor-Agt ( 118 ) of the LPAR failure (S 603 ), executes a failure process such as log acquisition at the time of LPAR failure (S 604 ), and terminates the process (S 605 ).
[0061] On the other hand, when the LPAR failure is caused by a recoverable factor, the hypervisor 117 performs a recovery process (S 606 ) and terminates the process (S 607 ).
[0062] Next, a command process in the Hypervisor-Agt ( 118 ) accompanied by a command execution request from the management server 101 will be described with reference to FIGS. 7 and 8 .
[0063] When receiving the command execution request transmitted from the management server 101 , the Hypervisor-Agt ( 118 ) performs a reception process (S 701 ). Since there are many kinds of commands to be requested, the Hypervisor-Agt ( 118 ) analyzes the types of the commands in the first place (S 702 ). In this example, the Hypervisor-Agt ( 118 ) performs a process of five commands of an LPAR deactivate command for deactivating the LPAR, an LPAR configuration information reading command, an LPAR configuration information writing command, an LPAR activate command for activating the LPAR, and an LPAR generating command.
[0064] In the case of the LPAR deactivate command, it is determined whether the LPAR to be deactivated is appropriate (S 703 ). When it is determined that the LPAR is not appropriate, an error process is performed (S 707 ), and the process is terminated (S 708 ). When it is determined that the LPAR 2 to be deactivated is appropriate, a process for deactivating the target LPAR 2 is performed (S 704 ). Then, it is determined whether or not the deactivate process is successfully completed (S 705 ). When the deactivate process fails, an error process is performed (S 707 ), and the process is terminated (S 708 ). On the other hand, when the deactivate process is successfully completed, transmission of the Hypervisor-Agt alert is requested to notify the completion of deactivate of the LPAR 2 , and the process is terminated (S 708 ).
[0065] In the case of the LPAR configuration information reading command, the configuration information of the target LPAR 2 is transferred to the management server 101 . Thereafter, it is determined whether or not the data transfer is successfully completed (S 710 ). When the data transfer is successfully completed, the process is terminated (S 712 ). On the other hand, when the data transfer fails, an error process is performed (S 711 ), and the process is terminated (S 712 ).
[0066] In the case of the LPAR configuration information writing command, the configuration information of the target LPAR 2 is transferred from the management server 101 to the hypervisor 127 . Thereafter, it is determined whether or not the data transfer is successfully completed (S 714 ). When the data transfer is successfully completed, the process is terminated (S 716 ). On the other hand, when the data transfer fails, an error process is performed (S 714 ), and the process is terminated (S 716 ).
[0067] Next, in the case of the LPAR activate command (see FIG. 8 ), it is determined whether the LPAR to be activated is appropriate (S 801 ). When the result shows that the LPAR is not appropriate, an error process is performed (S 805 ), and the process is terminated (S 806 ). On the other hand, when it is determined that the LPAR 2 to be activated is appropriate, a process for activating the target LPAR 2 is performed (S 802 ). Then, it is determined whether the activate is successfully completed (S 803 ). When the activate process fails, an error process is performed (S 805 ), and the process is terminated (S 806 ).
[0068] On the other hand, when the activate process is successfully completed, transmission of the Hypervisor-Agt alert is requested to notify the completion of activate of the LPAR (S 804 ), and the process is terminated (S 806 ).
[0069] Next, in the case of the LPAR generating command, the effective CPU performances in the original and destination server modules are computed (S 807 ). The effective CPU performance in the original server module is obtained by multiplying (the number of physical CPUs) by (the service ratio of the LPAR in the original server module). The effective CPU performance in the destination server module is computed by multiplying (the number of physical CPUs) by (100%−(service ratios of all LPARs that are being activated)).
[0070] Thereafter, there are determined the following three conditions (S 808 ), such as (1) the effective CPU performance in the destination server module is equal to or higher than that in the original server module by comparing the effective CPU performances with each other, (2) a memory in the destination server module is available, and (3) the NICs and HBAs equal to or larger in number than those used by the LPAR in the original server module are available in the destination server module.
[0071] When any one of the three conditions is not satisfied, it is determined that it is impossible to generate the LPAR. Then, an error process is performed (S 812 ), and the process is terminated (S 813 ).
[0072] On the other hand, when the three conditions are all satisfied, the target LPAR is generated (S 809 ). In this example, the LPAR 4 ( 124 ) is generated as a substitute for the LPAR 2 .
[0073] Thereafter, it is determined whether or not the generation of the LPAR is successfully completed (S 810 ). When the generation of the LPAR is successfully completed, transmission of the Hypervisor-Agt alert is requested to notify the completion of LPAR generation (S 811 ), and the process is terminated (S 813 ). On the other hand, when the generation of the LPAR fails, an error process is performed (S 812 ), and the process is terminated (S 813 ).
[0074] Next, a transmission process performed by the Hypervisor-Agt when transmission of the hypervisor alert is requested will be described with reference to FIGS. 9 and 10 .
[0075] When the transmission of the Hypervisor-Agt alert is requested, the Hypervisor-Agt ( 118 ) analyzes the type of the alert (S 902 ).
[0076] The result shows that the alert type is the completion of LPAR activate, an LPAR activate completion alert is transmitted (S 903 ), and the process is terminated (S 906 ).
[0077] The result shows that the alert type is the failure of LPAR activate, an LPAR activate failure alert is transmitted (S 904 ), and the process is terminated (S 906 ).
[0078] The result shows that the alert type is the occurrence of LPAR failure, an LPAR failure occurrence alert is transmitted (S 905 ), and the process is terminated (S 906 ).
[0079] The result shows that the alert type is the completion of LPAR deactivate, an LPAR deactivate completion alert is transmitted (S 1001 ), and the process is terminated (S 906 ).
[0080] The result shows that the alert type is the failure of LPAR deactivate, an LPAR deactivate failure alert is transmitted (S 1002 ), and the process is terminated (S 906 ).
[0081] The result shows that the alert type is the completion of LPAR generation, an LPAR generation completion alert is transmitted (S 1003 ), and the process is terminated (S 906 ).
[0082] The result shows that the alert type is the failure of LPAR generation, an LPAR generation failure alert is transmitted (S 1004 ), and the process is terminated (S 906 ).
[0083] In the above-described example, when a failure occurs in the LPAR of the server 111 , the LPAR is migrated to another while transmitting and receiving various information between the hypervisors in the original and destination server modules under the control of the management server 101 .
[0084] Further, the failure of the server can be detected from the SVP. Accordingly, even at the time of hardware failure, the LPARs operated on the hardware can be migrated to different physical devices.
[0085] As described above, according to the embodiment, when an LPAR failure occurs in the virtual computer system, the LPAR can be migrated to another while migrating detailed information. Accordingly, the embodiment can be applied to an operation using the virtual computer system in which efficiency is required. Further, when plural physical computers vary in performance, it is possible to easily migrate a specific LPAR among the physical computers.
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When a failure occurs in an LPAR on a physical computer under an SAN environment, a destination LPAR is set in another physical computer to enable migrating of the LPAR and setting change of a security function on the RAID apparatus side is not necessary. When a failure occurs in an LPAR generated on a physical computer under an SAN environment, configuration information including a unique ID (WWN) of the LPAR where the failure occurs is read, a destination LPAR is generated on another physical computer, and the read configuration information of the LPAR is set to the destination LPAR, thereby enabling migrating of the LPAR when the failure occurs, under the control of a management server.
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CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This patent application claims priority to German Application No. 102011083407.9, filed Sep. 26, 2011, the entire teachings and disclosure of which are incorporated herein by reference thereto.
FIELD OF THE INVENTION
[0002] The present invention relates to a residual gas burner for a fuel cell system and to a fuel cell system having such a residual gas burner.
BACKGROUND OF THE INVENTION
[0003] A residual gas burner is usually part of a fuel cell system. The fuel cell system additionally comprises at least one fuel cell, which comprises an anode and a cathode. For operating the fuel cell, an anode gas for the anode and a cathode gas for the cathode are necessary, which are fed to the cathode and to the anode respectively. Through the electrochemical reactions which take place in and/or on the anode and the cathode during the operation of the fuel cell, an anode waste gas and a cathode waste gas develop. The residual gas burner serves for the further usage of the cathode waste gas and of the anode waste gas, which are fed to the residual gas burner as educt gases. To this end, the residual gas burner comprises two educt gas feeds, which feed the respective educt gas to a combustion chamber of the residual gas burner. The respective educt gas feeds comprise outlet openings, through which the respective educt gas enters the combustion chamber where it is combusted. The heat created through the combustion of the educt gases can then be fed for example via a heat transfer device to the cathode gas upstream of the fuel cell in order to increase the efficiency of the fuel cell or of the fuel cell system. Disadvantageous here is that the residual gas burner, in particular due to a poor mixing-through of the educt gases in the combustion chamber, has a low efficiency. In addition, such residual gas burners are very heavy and through their design, are complex to manufacture.
SUMMARY OF THE INVENTION
[0004] The present invention therefore deals with the problem of stating an improved or at least alternative embodiment for a residual gas burner of the type mentioned at the outset, which is characterized in particular through an improved efficiency and/or through an easy and cost-effective design.
[0005] According to the invention, this problem is solved through the subjects of the independent claims. Advantageous embodiments are subject of the dependent claims.
[0006] The present invention is based on the general idea of equipping a residual gas burner for a fuel cell system with two educt gas feeds, each of which comprise at least one outlet opening for letting out a respective educt gas into a combustion chamber of the residual gas burner, and arranging the outlet openings of the one educt gas closer to the combustion chamber than the outlet openings of the other educt gas. Because of this, an improved mixing-through of the respective educt gases prior to the combustion takes place, which leads to an improved and more stable combustion or flame within the combustion chamber and consequently improves the efficiency of the residual gas burner. The modulation capability of the residual gas burner is also improved towards higher lambda values because of this.
[0007] In particular, first outlet openings of a first educt gas lie in a first plane, while second outlet openings of a second educt gas lie in a second plane, which is further distant from the combustion chamber than the first plane.
[0008] Corresponding to the inventive idea, the residual gas burner comprises a first educt gas feed and a second educt gas feed, which serve for the feeding of the first educt gas and of the second educt gas to the combustion chamber of the residual gas burner. In addition, the first educt gas feed comprises at least one first outlet opening for letting out the first educt gas into the combustion chamber and is arranged on a first top surface of a first outlet channel system of the first educt gas feed. Furthermore, the second educt gas feed comprises a second outlet channel system, which comprises a top surface, which for letting out the second educt gas into the combustion chamber, comprises at least one second outlet opening. The second top surface of the second outlet channel system and the first top surface of the first outlet channel system additionally face the combustion chamber, wherein the first outlet channel system has a first bottom facing away from the first top surface, which first bottom faces the second top surface. This means, in particular, that the second outlet channel system and thus the at least one second outlet opening are spaced further from the combustion chamber than the first outlet channel system and thus the at least one first outlet opening. The respective outlet channel systems can each comprise a channel or a plurality of channels, wherein at least one of the channels comprises at least one associated outlet opening. The outlet channel systems as well as the top surfaces and the bottom surfaces can have any shapes, they consequently do not necessarily have a flat shape.
[0009] Feeding the respective educt gas to the associated channels can be additionally realised by means of feeding channels. The respective educt gas feeds can comprise one or a plurality of such feeding channels, which feeds/feed the respective educt gas for example from an inlet of the associated educt gas feed or the associated outlet channel system to the respective channels via a channel inlet or a plurality of channel inlets.
[0010] With a preferred embodiment, the second outlet channel system is arranged on the first bottom surface of the first outlet channel system. Practically, the first outlet channel system and the second outlet channel system are designed as separate components. Preferred is an embodiment, wherein the respective educt gas feeds and thus the respective outlet channel systems are designed as separate components. The arrangement of the second outlet channel system and thus of the second top surface on the first bottom surface of the first outlet channel system means in particular that the educt gas feeds are directly adjacent. The educt gas feeds in this case can be mechanically connected to each other, wherein the connection between the educt gas feeds can be realised in any way, provided they are suitable for the temperatures and pressures that are present there or in the combustion chamber. The separate design of the respective educt gas feeds has as a consequence in particular that the residual gas burner can be assembled from individual modules. This leads to a simplified and thus cost-effective production of the residual gas burner. In addition, the feeds or the channel systems can be structured in a simple manner, which facilitates a cost-effective production.
[0011] Practically, the first outlet channel system comprises at least one passage opening which allows the second educt gas flowing through the at least one second outlet opening to pass into the combustion chamber. The respective passage opening is spaced from the at least one first outlet opening and in the direction of the combustion chamber is in alignment with the at least one second outlet opening.
[0012] Preferred are embodiments, wherein the respective outlet channel systems each have a plurality of outlet openings. Accordingly, the first outlet system can also have a plurality of passage openings, which are spaced from the first outlet openings and each of which is in alignment with at least one of the second outlet openings. With a further embodiment, at least two of the first outlet openings have a different size. Also conceivable are embodiments, wherein at least two of the first outlet openings additionally or alternatively have a different shape. The same applies to the second outlet openings. This means that at least two of the second outlet openings have a different size and/or shape.
[0013] Here, according to a further preferred embodiment, the residual gas burner can be designed so that the first outlet openings are designed larger than the second outlet openings. This is practical, in particular, with embodiments, wherein the first educt gas feed is designed for larger flow rates than the second educt gas feed. This means that the residual gas burner is designed in such a manner that a volume of the first educt gas that is larger than that of the second educt gas can enter the combustion chamber. The first educt gas feed to this end can be designed larger or provide a larger flow cross section than the second educt gas feed for the associated educt gas. Accordingly, the first outlet openings can then be designed larger than the second outlet openings.
[0014] According to a preferred embodiment, the first educt gas feed is designed U-shaped and comprises two legs. The first outlet channel system in this case is preferably formed with pipes which run parallel between the legs. At least one of the pipes, preferentially however all, each form a first channel of the first outlet channel system, wherein the respective pipes are spaced from one another along a direction that runs transversely to the parallel arrangement in order to form between said passage openings of the first outlet channel system. Accordingly, the legs of the U-shaped educt gas feed can be designed as first feed channels and feed the first educt gas to the pipes. The first educt gas feed can thus comprise two first feed channels, which feed the first educt gas to the pipes via the ends of the pipes facing the legs. The respective first outlet opening is additionally arranged on the first top surface and thus on the top surface of one of the pipes.
[0015] Additionally, the respective first feed channel can comprise at least one bypass opening, which is arranged laterally or in a marginal region of the combustion chamber or connected to a bypass path leading passed the combustion chamber. The bypass openings in particular serve the purpose of reducing the flow rate of the first educt gas into the combustion chamber. Within a combustion chamber of the residual gas burner, a marginal region can be provided laterally of the combustion chamber, which is not assigned any second outlet openings, so that there only the bypass openings are provided and only the first educt gas enters into the marginal region. The educt gas flow entering the combustion chamber via the bypass openings is then guided laterally along walls of the combustion chamber enclosing the combustion chamber, which means a thermal relief of the combustion chamber walls. Optionally, at least one bulkhead can be arranged in the combustion chamber, which runs parallel to a combustion chamber wall and in at least one region adjoining the first surface separates the marginal region from the combustion chamber. Distally to the first surface, the respective bulkhead can be overflowable, so that the respective marginal region there is fluidically connected to the combustion chamber. Insofar as the respective marginal region is separated from the combustion chamber through at least one such bulkhead, the marginal region includes the bypass path at least partially passing by the combustion chamber. The bypass openings are preferentially arranged also on the first top surface.
[0016] If the opening arranged on the first feed channel serves as bypass opening, the first educt gas flowing out through it can also be utilised for cooling the combustion chamber or the residual gas burner. The bypass opening is arranged for example between the corresponding bulkhead of the combustion chamber and an outer wall or combustion chamber wall of the residual gas burner. These walls form a hollow space through which the first educt gas flowing out of the respective bypass opening can flow, and through which hollow space the bypass path leads.
[0017] The second top surface of the second outlet channel system can be designed as plate. The plate delimits a second channel of the second outlet channel system, which supplies all second outlet openings with the second educt gas. In other words, the second outlet channel system can merely comprise one single second channel, which supplies all second outlet openings with second educt gas, wherein the second outlet openings are arranged in the plate and accordingly on the second top surface. Here, the second channel and a second feed channel coincide or correspond to each other at least partially.
[0018] With an advantageous further development, the second outlet channel system or the second educt gas feed is produced in shell design. Accordingly, the second top surface can be formed as a second top surface shell, which with a second bottom surface designed as a second bottom shell forms the second outlet channel system or the second educt gas feed.
[0019] Also preferred is an embodiment, wherein the first outlet channel system or the first educt gas feed is produced in shell design. Accordingly, the first educt gas feed comprises a first top surface shell and a first bottom shell designed complementarily thereto, which form the first outlet channel system or the first educt gas feed.
[0020] Preferred is an embodiment, wherein both the first outlet channel system or the first educt gas feed as well as the second outlet channel system or the second educt gas feed are produced in shell design. The respective shells, i.e. the respective top surface shells and/or the respective bottom shells are produced for example through a deep-drawing method. The respective shells can be formed from sheet metal, in particular of iron metals and/or light metals through the deep-drawing and subsequently connected to each other. As examples for connecting possibilities of the respective shells, welding, soldering, screwing or gluing are pointed out here, wherein any types of the connection of the respective associated shells are conceivable provided these connection types are suitable for the thermodynamic conditions prevailing in the combustion chamber. Through the shell design of the shells formed in particular from sheet metal, a cost-effective production of the educt gas feeds and thus of the residual gas burner is possible. In addition, the weight of the residual gas burner is reduced because of this, which is advantageous in particular with mobile applications of the associated fuel cell system.
[0021] According to a further embodiment, the first outlet openings are arranged along preferentially straight first lines. A plurality of first outlet openings can then be arranged on different first lines in each case, wherein the respective first lines are preferentially arranged next to one another, in particular lie in a first plane and run parallel. Accordingly, the second outlet openings with a further embodiment are arranged on in particular straight second lines, wherein the second lines are preferentially arranged next to one another, run parallel to one another and can in particular lie in a second plane. The respective outlet openings arranged on one of the lines can have different sizes and/or shapes.
[0022] The outlet openings arranged on one of the lines can in particular become smaller along a flow direction in the respective channel. In particular, this serves the purpose of homogenising a flow rate of the respective educt gas into the combustion chamber. This means, the respective outlet openings are dimensioned or formed in such a manner that a flow velocity through all first outlet openings and/or all second outlet openings in each case is substantially the same. Reducing the outlet openings along the corresponding flow direction is based on the knowledge that the pressure in the respective educt gas in the respective channel increases along the flow direction of the educt gas due to the damming-up of the educt gas in the respective channel system. This is countered, insofar, that the size and thus a flow cross section of the outlet openings along the flow direction becomes smaller, as a result of which the mass flow or flow rates through all outlet openings of the associated educt gas feed can be adapted to one another. If a channel is supplied with educt gas via two feed channels on two channel inlets located opposite, the outlet openings of this channel can consequently be formed in such a manner that its size decreases towards the centre of the arrangement on the line.
[0023] Alternatively or additionally, the homogenisation of the flow rate of the respective educt gas can be realised through adapting the size of the associated channel inlets. The respective channel inlets can for example comprise a constriction, wherein the throttling effect of the constrictions along the flow direction of the associated educt gas in the feed channel supplying the channels or in the feed channels supplying the channels, increases. In other words, the flow cross section made available through the channel inlets becomes smaller along the flow direction in the associated feed channels, so that the pressure in the educt gas which increases through the damming-up can be offset along the flow direction.
[0024] Here, an embodiment is preferred, wherein the respective constrictions are integrally formed in the associated outlet channel system. The constrictions are thus realised through different shapes or sizes of the channel inlets.
[0025] A further possibility for configuring a homogeneous flow rate is the reduction in size of the channels or of the flow cross sections of the channels along the flow direction of the associated feed channel or the associated feed channels.
[0026] Additionally or alternatively, the feed channel or the feed channels can taper along the flow direction of the educt gas flowing within them in order to reduce their flow cross section along the flow direction. This is practically the case when along the respective feed channel at least two associated channels or at least two associated outlet openings are arranged, which this second feed channel supplies with second educt gas.
[0027] Preferred is an embodiment, wherein the first lines and second lines are each arranged next to one another. The first lines and the second lines in this case are preferably arranged alternating along a direction transversely to the longitudinal directions of the straight lines, wherein this longitudinal direction preferably is the flow direction in the respective channels. If for example the channels of one of the outlet channel systems are designed as pipes, the corresponding lines can run in particular parallel to the pipes. This means that the associated outlet openings are arranged line-like on the top surface of the pipes.
[0028] The bypass openings of the first feed channels can also be arranged along bypass lines, which practically extend along the associated first feed channel. These run transversely, in particular perpendicularly to the first lines.
[0029] The passage openings can be formed through linear elongated holes or slits, which are arranged next to one another, run parallel to the first lines and alternate with these, while they can practically lie in the first plane and are aligned with the second lines preferably perpendicularly to the first plane.
[0030] According to an advantageous further development, the first outlet openings are arranged line-like on first lines along the first channels of the first outlet channel system formed as pipes and/or of the at least one first feed channel, while the second outlet openings are arranged line-like on second lines which are in alignment with the passage openings formed through the spaced pipes.
[0031] With a further preferred embodiment, one of the educt gas feeds is configured as anode waste gas ducting of the fuel cell system. Preferentially, the first educt gas feed designed for larger flow rates is configured as cathode waste gas ducting, while the second educt gas feed is configured as anode waste gas ducting. Here, use is made of the knowledge that during the operation of a fuel cell of a fuel cell system more cathode gas than anode gas is used and consequently more cathode waste gas than anode waste gas is incurred, wherein the cathode gas and the anode gas each are fed to at least one anode arranged on the anode side or at least one cathode arranged on a cathode side of at least one fuel cell of the fuel cell system. In addition, a cooling gas, e.g. air, can be admixed to the cathode waste gas upstream of the combustion chamber.
[0032] With an advantageous further development of the solution according to the invention, a fuel cell system comprises a residual gas burner of the type described above. The fuel cell system comprises the at least one fuel cell, which comprises the anode side and the cathode side. Practically, one of the educt gas feeds is fluidically connected to the cathode side, while the other educt gas feed is fluidically connected to the anode side. Thus, the anode waste gas generated on the anode side can reach the combustion chamber of the residual gas burner through one of the educt gas feeds, while the cathode waste gas generated on the cathode side is fed to the combustion chamber through the other educt gas feed. Here, an embodiment is preferred wherein the first educt gas feed, which is designed for larger flow rates than the second educt gas feed, is fluidically connected to the cathode side, while the second educt gas feed is fluidically connected to the anode side. Consequently, anode waste gas flows into the combustion chamber through the second outlet openings facing the bottom surface while cathode gas flows into the combustion chamber through the first outlet openings.
[0033] Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the associated Figure description by means of the drawings.
[0034] It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combination stated but also in other combinations or by themselves without leaving the scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein same reference characters refer to same or similar or functionally same components.
[0036] There it shows, in each case schematically,
[0037] FIG. 1 a highly simplified representation of a fuel cell system in the manner of a circuit diagram,
[0038] FIG. 2 a top surface view of a first educt gas feed and a second educt gas feed of a residual gas burner,
[0039] FIG. 3 a lateral view of the residual gas burner,
[0040] FIG. 4 an exploded representation of the residual gas burner.
DETAILED DESCRIPTION OF THE INVENTION
[0041] According to FIG. 1 , a fuel cell system 1 comprises at least one fuel cell 2 , which on an anode side 3 comprises an anode 4 and on a cathode side 5 comprises a cathode 6 . For operating the fuel cell system 1 , the anode 4 is supplied with an anode gas and the cathode 6 is supplied with a cathode gas. To this end, an anode gas feed 7 is provided, which feeds the anode gas to the anode 4 on the anode side 3 . In addition, a cathode gas feed 8 is provided, which feeds the cathode gas to the cathode 6 on the cathode side 5 . The fuel cell 2 converts the chemical energy that is created during the chemical reaction of the cathode gas and of the anode gas into electrical energy and feeds the electrical energy for example in the form of an electrical voltage to an electric consumer 10 by means of electrical lines 9 . In the process, anode waste gas generated on the anode side 3 and cathode waste gas on the cathode side 5 . The cathode waste gas and the anode waste gas are fed to a residual gas burner 13 of the fuel cell system 1 as a first educt gas (cathode waste gas) and a second educt gas (anode waste gas) via a cathode waste gas ducting 36 or a first educt gas feed 11 and an anode waste gas ducting 37 or a second educt gas feed 12 . The residual gas burner 13 comprises a combustion chamber 14 , which the educt gases enter by means of the first educt gas feed 11 and the second educt gas feed 12 . In the combustion chamber 14 a combustion of the educt gases takes place, in the process of which a hot burner waste gas is generated. The burner waste gas is conducted away from the residual gas burner 13 through a burner waste gas ducting 15 . The burner waste gas ducting 15 is connected to the cathode gas feed 8 by means of a heat transfer device 16 in a heat-transferring manner, so that the heat generated by the residual gas burner 13 is transferred to the cathode gas.
[0042] FIGS. 2 to 4 shows the residual gas burner 13 . The first educt gas feed 11 is designed U-shaped and comprises a first outlet channel system 17 , which comprises first channel 18 designed as pipes 18 , which run parallel between legs 19 designed as first feed channels 40 of the first educt gas feed 11 formed U-shaped. The channels 18 running parallel are additionally spaced from one another along a direction 38 running perpendicular to the parallel arrangement and thus form slit-like passage openings 20 of the first outlet channel system 17 . The first educt gas feed 11 and thus the first outlet channel system 17 additionally comprise a first top surface 21 facing the combustion chamber 14 delimited by walls 39 . For letting out the first educt gas into the combustion chamber 14 , first outlet openings 22 are arranged line-like along straight-line first lines 23 on the first top surface 21 of the first outlet channel system 17 , wherein in each case one of the first lines 23 runs along the pipes 18 . In addition, round bypass openings 47 are arranged on further straight bypass lines 46 along the first top surface 21 of the legs 19 . The bypass openings 47 are arranged laterally in a marginal region 48 of the combustion chamber 14 , so that the first educt gas flowing out through them is conducted laterally along the combustion chamber 14 . In a combustion chamber of the residual gas burner 13 , at least one bulkhead 39 can be provided, which separates the marginal region 48 from the actual combustion chamber 14 . Between the bulkhead 39 and a wall of the combustion chamber which is not shown, a hollow space can then be formed which serves as bypass path. Via this bypass path, the first educt gas can be conducted past the combustion chamber 14 . The bypass openings 47 running on the respective bypass lines 46 can thus be optionally arranged between such a bulkhead 39 of the combustion chamber 14 and an outer wall of the residual gas burner 13 which is not shown here, so that the bypass path leads through the hollow space thus formed and the associated educt gas can cool the residual gas burner 13 in the process. The respective bulkhead 39 can be configured overflowable distally from the first top surface 21 , so that the first educt gas enters the combustion chamber 14 from the bypass path there. If however such a bulkhead is missing, the first educt gas flowing along the outer wall of the combustion chamber can already enter the combustion chamber 14 along the walls. However, the first educt gas flowing along the combustion chamber wall can form a protective layer which reduces a thermal loading of the combustion chamber wall.
[0043] The first outlet openings 22 have a round shape, wherein the size of the first outlet openings 22 on the respective pipes 18 decreases towards the centre of the respective pipe 18 . The centre in this case refers to the spacing between the legs 19 of the first educt gas feed 11 running along the respective pipe 18 . The decrease of the size of the first outlet openings 22 is thus present along a first flow direction in the first outlet channel system 17 indicated through arrows 41 . The legs 19 of the first educt gas feed 11 merge into a first inlet 24 of the first outlet channel system 17 . The first educt gas thus flows from the fuel cell 6 via the first inlet 24 into the respective leg 19 and subsequently through the bypass openings 47 . Additionally, the first educt gas flows via the first inlet 24 into the respective leg 19 and via first channel inlets 42 into the respective pipes 18 and through the first outlet openings 22 into the combustion chamber 14 . All first channel inlets 42 , except for the channel inlets 42 of the pipe 18 next adjacent to the first inlet 24 each additionally comprise a constriction 43 , wherein the constrictions 43 increase in size along the flow direction 41 in the legs 19 . In addition, the constrictions 43 are integrally formed in the respective associated pipe 18 or in the first outlet channel system 17 . Accordingly, the respective constriction 43 can be described as bottle neck of the associated pipe 18 .
[0044] The second educt gas feed 12 comprises a second outlet channel system 25 , which comprises a second top surface 26 facing the combustion chamber 14 . In order to let the second educt gas flow into the combustion chamber 14 , round second outlet openings 27 are linearly arranged on the second lines 28 running linearly along second channels 44 arranged in parallel and on the second top surface 26 of the second outlet channel system 25 . The second top surface 26 faces a first bottom surface 29 of the first outlet channel system 11 facing away from the combustion chamber 14 . With the view shown in FIG. 3 , the second outlet openings 27 are thus arranged below the first outlet openings 22 so that the second outlet openings 27 are spaced further from the combustion chamber 14 than the first outlet openings 22 . In addition, the bypass openings 47 are arranged above the first outlet openings 22 . Furthermore, the second lines 28 are arranged parallel to the first lines 23 running along the pipes 18 and perpendicularly to the bypass lines 46 running along the legs 18 in such a manner that they and thus the second outlet openings 27 run aligned with the passage openings 20 designed slit-like perpendicularly to a plane in which the first lines 23 lie. Thus, the second educt gas flowing through the second outlet openings 27 can enter the combustion chamber 14 through the passage openings 20 . The bypass openings 47 arranged along the bypass lines 46 running parallel to the legs 19 furthermore form the intersection between these first lines 23 and the second lines 28 in the top surface view shown in FIG. 2 , so that along the flow direction in the first feed channels 40 , the bypass openings 47 and the first channel inlets 47 alternate.
[0045] As is evident in FIG. 3 , the second outlet channel system 25 is arranged on the first bottom surface 21 of the first outlet channel system 17 by means of the second top surface 26 . In addition, the second outlet channel system 25 comprises a single second feed channel 30 , which supplies all second channel 44 with second educt gas. The second feed channel 30 in this case is arranged in the middle of the second educt gas feed 12 . The second outlet openings 27 and the second channels 44 are formed in a second outer shell 31 facing the combustion chamber 14 of the second educt gas feed 12 produced in shell design. The second educt gas feed 12 comprises a second inlet 33 for letting in the second educt gas into the second outlet channel system 17 , so that the second educt gas reaches into the second feed channel 30 along a second flow direction of the second educt gas indicated by arrows 45 via the second inlet 33 and then via the second channels 44 , the second outlet openings 27 and following this enters the combustion chamber 14 through the passage openings 20 . The second feed channel 30 additionally tapers along the second flow direction in the second feed channel 30 .
[0046] The first educt gas feed 11 , too, as is evident in FIG. 4 , is produced in shell design. To this end, the first educt gas feed 17 comprises a first upper shell 34 facing the combustion chamber 14 and a first lower shell 35 formed complementarily thereto and facing away from the combustion chamber 14 . In FIG. 4 , the region of the first inlet 24 is shown in the assembled state.
[0047] The respective lower shells 32 , 35 and upper shells 31 , 34 are each preferentially produced from a metal sheet through a deep-drawing method. In addition, the first educt gas feed 11 and the second educt gas feed 12 are formed as separate components. This makes possible a light, cost-effective and simple production of the residual gas burner 13 . In addition, by arranging the first outlet openings 22 and the second outlet openings 27 and the suitable constrictions 43 and the taper, an improved mixing-through of the educt gases can take place, as a result of which the combustion of the educt gases in the combustion chamber 14 of the residual gas burner 13 is stabilised, which leads to an increase of the efficiency of the residual burner 13 .
[0048] As is evident in particular in FIGS. 3 and 4 , the first educt gas feed 11 is designed for larger gas flow rates than the second educt gas feed 12 , so that the first educt gas feed 11 with approximately identical flow velocities, makes possible larger flow rates than the second educt gas feed 12 . The fact that the different-size first outlet openings 22 are larger than the identical-size second outlet openings 27 also contributes to this.
[0049] Preferably, the first educt gas feed 11 is fluidically connected to the cathode side 5 , while the second educt gas feed 12 is fluidically connected to the anode side. In particular, this means that the first educt gas feed 11 is configured as the cathode waste gas ducting 36 while the second educt gas feed 12 is configured as the anode waste gas ducting 37 .
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The present invention relates to a residual gas burner ( 13 ) for a fuel cell system ( 1 ) having to educt gas feeds ( 11, 12 ) for feeding an educt gas each to a combustion chamber ( 14 ) of the residual gas burner ( 13 ). An improved operation of the residual gas burner ( 13 ) is obtained when the educt gas feeds ( 11, 12 ) each comprise outlet openings ( 22, 27 ), wherein the outlet openings ( 22, 27 ) face the combustion chamber ( 14 ) and the outlet openings ( 22, 27 ) of one of the educt gas feeds ( 11, 12 ) face a first bottom surface ( 29 ) of the other educt gas feed ( 11, 12 ).
In addition, the invention relates to a fuel cell system ( 1 ) having such a residual gas burner ( 13 ).
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FIELD
Embodiments of the invention relate to etching techniques used in semiconductor processing, and more specifically to repairing and passivating “low-k” interlayer dielectric films following plasma-based etching during dual damascene integration of copper interconnects.
BACKGROUND
The semiconductor industry is currently amidst a paradigm shift from aluminum interconnects with silicon dioxide (“SiO 2 ”) interlayer dielectrics to copper interconnects with interlayer dielectrics having dielectric constants lower than that of silicon dioxide (“low-k dielectrics”). This change has been mandated by decreasing critical dimensions, as from the current 0.18 micron technology node to state-of-the-art 0.13 micron and smaller technology nodes.
Two of the performance limiting factors of aluminum/silicon dioxide interconnect/dielectric technology are the resistivity of aluminum and dielectric constant of SiO 2 . As the integrated circuit feature size decreases, the distance between interconnect layers and conducting pathways decreases. Since the capacitance between the interconnects and pathways is inversely proportional to the distance, all else being equal, decreasing feature sizes increases capacitance. Given that an integrated circuit's performance is limited by resistance/capacitance interactions (“RC constant”), capacitive coupling, and power consumption, lowering either the capacitance, resistance, or both permits faster integrated circuit speeds for a given critical dimension.
The switch from aluminum to copper interconnects equates to a 37% decrease in resistivity and improves the RC constant for a given capacitance. However, the switch from SiO 2 to lower dielectric constant dielectrics (to decrease the capacitance factor of the RC constant) is not so well defined. There are myriad choices for the dielectric material and deposition process.
An early forerunner in low-k dielectrics was fluorine doped silicon oxide, or fluorosilicate glass (“FSG”). The appeal was that an FSG film could be deposited in the same manner as the undoped film, allowing the use of the same processing techniques and machines. However, the dielectric constant of fluorinated silicon dioxide is not substantially lower (3.3-3.5) than undoped silicon dioxide (3.9-4.2). Further, fluorinated silicon oxide absorbs water and has mechanical properties that may limit its use as a low-k dielectric.
Another popular material is carbon doped oxide, or organosilicate glass (“OSG”). Generally speaking, the OSG films have an Si w C x O y H z structure wherein the tetravalent silicon has a variety of organic group substitutions. The most common substitution is a methyl (CH 3 ) group provided by an organic precursor gas like trimethylsilane or tetramethlysilane (“3MS” and “4MS” respectively). In OSG the amorphous SiO 2 network is sporadically interrupted by the organic group, decreasing the density of the film. Like with FSG, the lower density of OSG compared to undoped SiO 2 decreases the dielectric constant. Also like FSG, OSG exhibits certain thermal and mechanical difficulties with current semiconductor processing techniques. Though widely accepted as a low-k dielectric solution, OSG does not offer significantly low dielectric constant values.
FIG. 1 illustrates a cross section of a copper dual-damascene architecture utilizing a low-k interlayer dielectric (“ILD”). A substrate 100 contains any variety of semiconductor devices well known to those skilled in the art as represented rudimentarily by source and drain regions 101 , dielectric 120 , and gate 121 of a metal oxide semiconductor (“MOS”) transistor. Interconnect levels 104 , 106 , and 108 are representative of, for example, the trench level of a copper dual-damascene interconnect structure, for which via levels 103 , 105 , and 107 provide electrical contact between interconnect layers and between interconnect layers and semiconductor devices. ILD layers 109 through 114 are formed of low-k dielectric material. The ILDs not only isolate interconnects on different layers, but also isolate interconnects on the same layer. Passivation layer 115 completes the interconnect stack.
FIG. 2 a illustrates a cross section of a substrate 200 utilizing a via-first, dual-damascene process. Specifically, FIG. 2 a illustrates substrate 200 following via and trench feature etches and prior to an antireflective coating (“ARC”) 203 layer removal from the planar surface of an ILD 202 and from within the previously etched via feature. Substrate 200 can be any material onto which an additional interconnect system (dielectric, via, and trench layers) will be added. For example, substrate 200 could be device-containing silicon, or it could be another interconnect system as illustrated by FIG. 1 . Etch stop 201 is a deposited material (e.g., silicon nitride, silicon carbide, and silicon oxy nitride) that aids etch selectivity during certain steps of the copper dual-damascene process. Exposure to plasma used to etch the via and trench features has removed surface organic groups of ILD 202 as illustrated by depleted dielectric surface 204 . Without surface organic groups, the dielectric constant of ILD 202 is greater than that of the pristine ILD 202 material. The depleted dielectric surface 204 is unprotected against fluoride-based aqueous chemistries to which it may be exposed during subsequent processing steps.
FIG. 2 b illustrates substrate 200 of FIG. 2 following the wet etch step to remove ARC 203 layer from both the surface of ILD 202 and from within the previously etched via feature. Fluoride-based aqueous chemistries during the wet etch of ARC 203 and subsequent cleaning steps have further damaged the surface of ILD 202 . As noted with reference to FIG. 2 a , the plasma used to etch the via and trench features has removed ILD 202 surface organic groups, making the resulting unprotected, hydrophilic surface of ILD 202 more vulnerable to attack by the wet etch chemistries. Between the damage caused by the via and trench plasma etches (specifically the removal of the surface organic groups) and the ARC 203 wet etch, ILD 202 has been rendered useless for both physical and chemical reasons as illustrated by damaged dielectric surface 205 . Not only has the dielectric constant of ILD 202 increased, but the critical dimension (the smallest separation of layers, features, etc. tolerable for functional devices, shown as the ILD 202 thickness separating two trench features) has also been compromised as illustrated by threatened critical dimension 206 .
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 : illustration of prior art substrate cross-section showing a low-k dielectric layer in via and trench levels of a copper dual-damascene architecture.
FIGS. 2 a and 2 b : illustrations of prior art substrate cross-section following the trench etch and following the anti-reflective coating removal showing a damaged interlayer dielectric and threatened critical dimension in a via-first copper dual-damascene process.
FIG. 3 : illustration of substrate cross section following photoresist patterning in preparation for the via etch in a via-first copper dual-damascene process.
FIG. 4 : illustration of substrate cross-section following the via etch, photoresist removal, and subsequent cleans in a via-first copper dual-damascene process.
FIG. 5 : illustration of substrate cross-section following the repair and passivation of the low-k interlayer dielectric exposed during the via etch by surface organic group replenishment.
FIG. 6 : illustration of substrate cross-section following deposition of an anti-reflective coating and photoresist patterning in preparation for the trench etch.
FIG. 7 : illustration of substrate cross-section following trench etch and photoresist removal.
FIG. 8 : illustration of substrate cross-section following the repair and passivation of the low-k interlayer dielectric exposed during the trench etch by surface organic group replenishment.
FIG. 9 : illustration of a substrate cross-section with all exposed low-k interlayer dielectric surfaces repaired and passivated by surface organic group replenishment, following the removal of the anti-reflective coating, with an intact critical dimension.
FIG. 10 : illustration of substrate cross section following via clean, barrier level deposition, copper deposition, planarization, and cap deposition.
FIG. 11 : system diagram of gaseous phase repair and passivation of silicon-containing low-k interlayer dielectric surfaces.
FIG. 12 : molecular diagram of the amorphous replenished and passivated low-k interlayer dielectric material.
DETAILED DESCRIPTION
Embodiments of a method for replenishing surface carbon and surface passivation of low-k, porous, silicon-based dielectric materials is described. Reference will now be made in detail to a description of these embodiments as illustrated in the drawings. While the embodiments will be described in connection with these drawings, there is no intent to limit them to drawings disclosed therein. On the contrary, the intent is to cover all alternatives, modifications, and equivalents within the spirit and scope of the described embodiments as defined by the accompanying claims.
Many natural interfaces between dissimilar materials involve at least one material that contains silicon. In the realm of semiconductor manufacture, almost all material interfaces involve either coincidental or purposeful contact between silicon containing materials. Due to both the omnipresence of siliceous interfaces in nature, and the specific importance of siliceous interfaces in semiconductor technology, significant industrial import attaches to any corresponding chemistry and chemical know-how.
Briefly, an embodiment of the invention is a method for chemically repairing and passivating surfaces of low-k interlayer dielectric materials following certain steps of semiconductor manufacture. By exposing ILD surfaces damaged by plasma to a silane coupling agent, the damaged ILD surface can be chemically repaired. The repaired ILD surface further becomes protected from subsequent processing steps. The embodiment helps bring semiconductor processing technology in line with the current state of low-k dielectric material development. For example, many existing porous, silicon-containing materials exhibit favorably low dielectric constants. However, the materials are often incompatible with various manufacturing steps for precisely the same physical and chemical arrangements that enable the materials to be low-k. The embodiment helps transform the theory of a copper/low-k dielectric process to reality by improving the characteristics of the low-k dielectric material at its interface with surrounding materials and manufacturing environments.
FIGS. 3 through 10 illustrate, in detail, an embodiment of the invention as applied to a via-first, copper dual-damascene process. Though the figures represent various processing steps of an embodiment, for the sake of simplicity, they do not display every process step. One skilled in the art will recognize where illustrations of steps have been omitted, and will understand how and when the detailed steps fit into the overall manufacturing process. One skilled in the art will also appreciate that for clarity certain layers are disproportionately illustrated in the figures.
As generally illustrated by FIG. 1 and specifically illustrated by FIGS. 3 through 10 , a dual-damascene architecture is a interconnect system utilizing multiple layers of interconnects with multiple layers of vias providing electrical contact between adjacent copper interconnect layers. Dual-damascene further refers to a process by which deposited metal is not etched; instead, the metal is deposited in features etched in dielectric layers, after which the excess metal is removed (and entire wafer surface planarized) using chemical mechanical polishing (“CMP”). Stated differently, both the metal interconnect lines and vias are deposited without an intervening metal etch step. This allows the use of metals, such as copper, that are not readily etched. Via-first refers to the order in which the trench and via features are etched. For via-first, the via feature is etched through the entire thickness of the ILD before the trench feature is etched through a portion of the ILD thickness. Conversely, for trench-first, the trench feature is etched partially through the thickness of the ILD before the via feature is etched through the remaining ILD thickness at the base of the trench feature.
An embodiment of the invention focuses on the interface between porous, low-k, silicon based dielectric materials with adjacent materials and environments (e.g., ILD 302 and its compatibility with wet etch chemicals) faced by the low-k dielectric material during various processing steps. Though an embodiment will be discussed with reference to a via-first, copper dual-damascene process flow, one skilled in the art will appreciate that other process flows (e.g., trench-first copper dual-damascene, or self-aligned variants thereof as described above) can benefit from the invention.
Additionally, though an embodiment will further be discussed with reference to specific materials and chemical compounds, one skilled in the art will realize that the artistry of the invention is also a novel approach to combining materials and processes more than simply utilizing materials themselves.
FIG. 3 illustrates a cross section of a substrate 300 utilizing a via-first, copper dual-damascene process following an etch stop 301 deposition, an ILD 302 deposition, an ARC 303 deposition, and a photoresist 304 deposition and patterning. The photoresist 304 has been patterned using standard photolithographic patterning processes as is well known in the art. Substrate 300 can be any material onto which an additional interconnect system (via, trench, and dielectric layers) will be added. For example, substrate 300 could be device-containing silicon, or it could be another interconnect system as illustrated by the interconnect layer stack of FIG. 1 . Etch stop 301 is a deposited material (e.g., silicon nitride, silicon carbide, and silicon oxy nitride) that aids etch selectivity during certain steps of the copper dual-damascene process. Though illustrated in FIG. 3 , an ARC 303 layer may be omitted in an embodiment of the invention depending on the requirements of the via feature etch. The ILD 302 layer will be detailed as an embodiment of the invention relies on the specific chemistry the ILD 302 layer material.
In an embodiment, ILD 302 has a low dielectric constant. The low-k nature of the ILD 302 material allows a fuller utilization of low-resistance copper interconnect lines and smaller critical dimensions by possessing a lower RC constant between adjacent trenches, vias, and layers for a given smaller critical dimension. In other words, for a given critical dimension, the combination of copper and a low-k ILD 302 enhances the performance of the myriad devices that in combination form an expansive number of semiconductor products.
An ideal ILD 302 would have a dielectric constant less than 3.0. It would further be compatible with current processing flows without requiring additional dedicated tools and process steps (e.g., anneals that would disturb devices, ex situ steps for which the wafers would be externally transferred from one machine to another, etc.). Mechanically speaking, the dielectric film would adhere properly to adjacent layers, not be prone to cracking, and have bulk modulus properties compatible with the rigors of manufacture. The film would finally exhibit thermal and chemical properties compatible with existing process flows. Unfortunately, some selections for dielectric materials exhibit favorable electrical properties at the expense of chemical and mechanical properties. Many standard processing steps currently used in production degrade or destroy low-k dielectrics (specifically porous, low-k dielectrics) rendering them practically useless despite their theoretical promise.
As mentioned, there are a variety of materials available that can potentially serve as ILD 302 . Certain materials such as carbon doped oxides rely on decreased density of their amorphous molecular networks and less polar Si—C linkages to achieve lower dielectric constants. Other materials also incorporate voids or pores in their structure where the voids and pores not only represent molecular network interruptions, but also represent localized absences of material. Such porous materials are often called “nanofoams.” The porosity of the material offers significant improvement in dielectric constant; however, integrating such materials in conventional processing steps is more challenging.
Although a variety of organic and inorganic materials demonstrate desirable dielectric properties, most nevertheless fail other processing or mechanical requirements. Common film problems associated with FSG, OSG, and organic nanofoam compounds include poor adhesion, cracking, via poisoning/contamination, chemical incompatibility, and bulk modulus mismatches that cause device breakage during wirebonding or packaging.
Examples of devastating process steps include etches to create the via and trench features in a copper dual-damascene architecture. Another example of a devastating process step is a selective wet etch between adjacent silicon containing layers (e.g., a silicon-based ILD 302 and a silicon-based ARC 303 or ARC 601 utilized for improving via and trench photolithographic patterning characteristics). Given the high aspect ratios (as high as 5:1 depth:width) and small critical dimensions of current and future etched features, any interlayer dielectric degradation could result in catastrophic critical dimension “blow-ups” or failures. Leading edge implementation of low-k ILD 302 may include the selection of the proper dielectric material and adoption of processing techniques that are compatible with the material.
Another critical aspect of using a low-k ILD 302 is the dielectric material's susceptibility to damage during etching, ashing, and priming processing steps. The ashing and priming steps expose photoresist and antireflective coating material, respectively, to plasma to prepare each for solvent and/or wet etch removal. During each step the dielectric material is exposed to damaging techniques. Some approaches to producing a commercially viable low-k dielectric materials have focused on non-porous, organic, silicon-containing, or siloxane-based, material (“sILD”). During oxygen-containing and oxygen-free plasma etches, ashing, and priming, common to creating the via and trench etches of a copper dual-damascene architecture, the plasma oxidizes and removes the sILD surface carbon. What remains is an SiO 2 -type surface, with a higher dielectric constant than the pristine sILD, that is readily attacked by fluoride ions during subsequent wet etch and cleaning steps.
In an embodiment, ILD 302 is a porous, silicon-containing material. Porous ILD 302 materials, including those based on hydrosilesquioxane (“HSQ”) and methylsilesquioxane (“MSQ”), can have porosities as high as 40%. Such porosity enables the materials to have desirably low dielectric constants, but also exacerbates the processing problems described with reference to the non-porous sILD materials. Whereas the methyl or organic groups of the non-porous sILD material aggregate at the sILD surface, and establish a hydrophobic barrier, the lower bulk organic content of the porous ILD 302 materials reduces such an effect. Furthermore, while the non-porous sILD material can perhaps withstand a fluoride-containing wet etch (even after its surface organic groups have been oxidized and removed), a porous ILD 302 material cannot. Given its porosity and lower bulk organic content, a porous ILD 302 exposes a greater area of unprotected (e.g., hydrophilic) surface to the attacking fluoride ions than the non-porous sILD.
An embodiment of the invention replenishes carbon on the surface of the porous ILD 302 material to both restore the material's low dielectric constant and passivate the surface, thereby creating a coating to withstand exposure to wet etch chemistries. One way to supply carbon to a hydrophilic surface is by chemical reaction with silane coupling agents like organochloro- or organoalkoxy-silanes. The reactions can occur within various environmental conditions, and through exposure to both liquid and vapor phases of the silane coupling agent. Silane coupling agents that may be used include but are not limited to disilazane, trichlorosilane, trimethoxy silane, triethoxy silane, silanol, siloxane, disiloxane, n-dodecyltrichlorosilane, and octyltrichlorosilane. In an embodiment, given the requirements of producing a non-polar and highly hydrophobic coating on porous ILD 302 , the silane coupling agent is hexamethyldisilazane (“HMDS” or (CH 3 ) 3 SiNHSi(CH 3 ) 3 ). In another embodiment, given requirements of producing a polar and hydrophilic coating, the silane coupling agent is 3-aminopropyltriethoxysilane (C 9 H 23 NO 3 Si).
Making the surfaces of the porous ILD 302 hydrophobic, however, is only a partial solution. During certain processing steps, the entire exposed surface is ILD 302 . During other steps, multiple materials are exposed. Particularly, as will be discussed with reference to FIG. 7 , following the trench etch in a via-first, copper dual-damascene architecture, the ARC 601 and ILD 302 surfaces are both exposed. The ARC 601 material both on the planar surface of ILD 302 and filling the etched via feature must be selectively removed without damaging the ILD 302 through which the via and trench are etched. Replenishing and passivating the ILD 302 surface is useful if the ARC 601 surface is not passivated, such that during ARC 601 removal the wet etch chemistries readily attack the non-passivated ARC 601 surface while leaving the hydrophobic ILD 302 surface intact. The wet etch selectivity in turn depends on replenishment and passivation selectivity.
Though passivation may be discussed in absolute terms (e.g., “complete” passivation) and surfaces described as having a hydrophobic or hydrophilic coating, it should be understood that each denotation refers to a range of surface energies for which the relative difference in surface energy between two distinct surfaces or materials is sufficient to enable material selective etching.
FIG. 4 illustrates a cross section of a substrate 300 utilizing a via-first, copper dual-damascene process following the processes illustrated by FIG. 3 and after the via feature etch. The plasma used to etch the via feature (and to ash photoresist 304 and prime ARC 303 , if present, of FIG. 3 ) has removed the surface organic groups of ILD 302 , as illustrated by a depleted dielectric surface 401 , adversely increasing the dielectric constant of ILD 302 . In an embodiment, the surface organic group is carbon.
FIG. 5 illustrates a cross section of substrate 300 utilizing a via-first, copper dual-damascene process following the processes illustrated by FIG. 4 and after the surface organic group replenishment and passivation of an embodiment of the invention. A coating 501 , or the replenished and passivated surface of the ILD 302 , is an embodiment of the invention for which there are two distinct results. The first result is that the ILD 302 's surface organic groups have been replenished, lowering the dielectric constant to a value approaching the dielectric constant of pristine ILD 302 material. The second result is ILD 302 surface passivation tuned to alter the surface energy, or wetting characteristic, of exposed ILD 302 to make the surface hydrophobic. As will become clear with discussion of additional figures, the coating 501 of exposed ILD 302 protects ILD 302 from the aqueous chemistries associated with subsequent wet etch processing steps. Furthermore, depending on the choice of etch stop 301 material, the coating 501 will also form on the surface of the exposed etch stop 301 at the base of the via feature.
FIG. 6 illustrates a cross section of substrate 300 utilizing a via-first, copper dual-damascene process following the processes illustrated by FIG. 5 and after the deposition of an ARC 601 layer and a photoresist 602 layer. The additions of ARC 601 layer and photoresist 602 layer prepare ILD 302 with coating 501 to be patterned for the trench feature etch. ARC 601 is common in the art and enables clean, high aspect ratio (as high as 5:1 depth:width) etched features by attenuating reflections that create notched surfaces on the vertical walls of the etched feature.
The ARC 601 material can be any of a variety of glasses containing organic dyes as is well known in the art. The organic dyes are optically absorbent to facilitate the reflection attenuation as noted above. In general, the ARC 601 chemistry is similar (and in an embodiment almost identical) to the ILD 302 chemistry. The similar chemistry between the ARC 601 and ILD 302 materials facilitates the trench feature etch, as the trench feature etch (further detailed with reference to FIG. 7 ) must remove both materials at approximately the same rate. If the chemistry of the ARC 601 material were substantially dissimilar to the chemistry of the ILD 302 material, the bottom of the trench feature may not be flat as the ARC 601 and ILD 302 materials will be removed at different rates.
FIG. 7 illustrates a cross section of substrate 300 utilizing a via-first, copper dual-damascene process following the processes illustrated by FIG. 6 , after the trench etch, and after photoresist 602 removal. Like the via feature etch, the trench feature etch is performed using plasma etching techniques as is well known in the art. The plasma etch has removed portions of ILD 302 to create the trench feature, with the resulting etched ILD 302 surfaces being damaged (by the plasma removing surface organic groups) as discussed with reference to the initial via feature etch as illustrated by FIG. 4 , and as illustrated by a depleted dielectric surface 701 . Exposed surfaces of ILD 302 are further damaged by plasma ashing and priming steps used to prepare photoresist 602 and ARC 601 , respectively, for removal by the same mechanism discussed with reference to the plasma via feature etch.
FIG. 8 illustrates a cross section of substrate 300 utilizing a via-first, copper dual-damascene process following the processes illustrated by FIG. 7 , after the surfaces of ILD 302 exposed during the trench etch have had their surface organic groups replenished and surfaces passivated. In an embodiment, the surface organic group replenishment and passivation of the invention only effect ILD 302 . In other words, the exposed surfaces of ARC 601 do not become as hydrophobic as the surfaces of ILD 302 such that the standard fluoride-based aqueous etch used to remove ARC 601 becomes ineffective. As noted, selective passivation based on novel selection of ARC material, ILD material, and silane coupling agent enables the selective etching necessary to create clean etch features, with intact critical dimensions, in systems that benefit from the use of low-k dielectric materials.
It is important to note that novel coatings 501 and 801 are created during different processing stages. While in an embodiment they are chemically identical, as each is a reaction product of the same ILD material exposed to the same silane coupling agent, one skilled in the art may recognize that the coatings do not necessarily have to be the same. In either case, it is important that each coating be formed to properly protect ILD 302 . Coating 501 , the formation of which necessarily occurs before ARC 601 material is deposited, is particularly important in protecting the walls of the via feature during ARC 601 removal, etch stop 301 removal, and subsequent via cleans that physically open the via to either substrate 300 or additional, previously deposited interconnect layers. Coating 801 repairs and protects the ILD 302 material exposed and damaged during the trench feature etch, and primarily protects the critical dimension separating adjacent trench features. The novel method of an embodiment of the invention includes forming not only a single coating, but also a combination of coatings.
The novel wet etch selectivity between the ARC 601 and porous ILD 302 is determined by both coating 501 and coating 801 . The creation of coatings 501 and 801 is determined by the surface density and relative size of the organic groups present in the distinct ARC 303 , ARC 601 , and ILD 302 materials. The replenishing and passivating silylation/silanization reaction (e.g., exposure to a silane coupling agent) involves the reaction of ILD 302 surface Si—OH bonds to form Si—O—Si* bonds wherein the * indicates an attached hydrocarbon side-group. The ARC 302 and ARC 601 surfaces are comprised of bulky organic groups (e.g., aromatic or tertiary carbon species like isopropyl) that sterically hinder silanization because the bulky organic groups are impermeable to the reactive species of the silane coupling agent. Si—O—Si* bonds do not form on either the ARC 303 or ARC 601 surface. However, the bulky organic groups on the surface of ARC 303 and 601 are permeable to smaller fluoride ions (F—), such that the ARC 303 and ARC 601 can still be etched using fluoride-based aqueous chemistries. Examples of fluoride-based aqueous chemistries include HF, NH 4 F, BOE and combinations thereof with other solvents or corrosives as is well known in the art. Conversely, the smaller organic groups (e.g., methyl or linear alkyl chains) comprising the ILD 302 surface readily facilitate the diffusion of silane coupling agents, enabling the ILD 302 surface to be passivated as represented by coatings 501 and 801 . The result, through creative material selection for the ARC 303 , ARC 601 , ILD 302 , and silane coupling agent, is a process wherein the ILD 302 surface is passivated and protected (e.g., a coating formed thereon) while wet etch chemistries readily attack and remove the ARC 601 material.
FIG. 9 illustrates a cross section of substrate 300 utilizing a via-first, copper dual-damascene process following the processes illustrated by FIG. 8 and after ARC 601 removal using standard fluoride-based aqueous etch techniques as is well understood in the art. The remaining architecture, after removing etch stop 301 at the bottom of the via feature and appropriate cleaning steps, is ready for diffusion barrier and copper deposition as is well understood in the art. The noteworthy benefits of an embodiment of the invention are twofold. Exposure to a silane coupling agent has replenished an ILD 302 surface organic group, lowering the dielectric constant ILD 302 to that of pristine ILD 302 material. Coatings 501 and 801 formed by the replenishment have protected ILD 302 from the wet etch chemistries used to remove ARC 601 . The resulting topography is dimensionally superior to and more physically and chemically sound than the topography created in absence of an embodiment of the invention as illustrated by intact critical dimension 901 .
FIG. 10 illustrates a cross section of substrate 300 utilizing a via-first, copper dual-damascene process following the processes illustrated by FIG. 9 and after etch stop plasma etch (including removing the coating 501 from the surface of the etch stop, if present), barrier 1001 deposition, copper 1002 deposition, CMP planarization, and cap 1003 deposition. Once the deposited copper has been planarized and capped, an interconnect level in the copper dual-damascene process is complete. Cap 1003 can be a substrate for subsequent interconnect layers by repeating the preceding process steps. Cap 1003 can further serve as a final passivation should copper 1002 be the hierarchical top of an interconnect stack.
FIG. 11 illustrates a vapor exposure system 1100 (in which the vacuum and electrical sources have been omitted for simplicity) used to enact an embodiment of the invention through gaseous phase interactions. An exposure chamber 1101 houses wafers 1102 during exposure. Recipe/Flow Control 1103 controls the pressure and flow of the individual source gases to facilitate the silane coupling agent exposure. The temperature and/or pressure of the exposure chamber 1101 may be adjusted to maintain the vapor phase of the silane coupling agent. Source gases 1104 , including individual gases 1105 - 1107 , can be silane coupling agent constituents, inert carrier gases that do not participate in any chemical reaction (e.g., argon or helium), or combinations thereof. Alternatively or additionally, the silane coupling agent can be provided by a single source as illustrated by silane coupling agent 1108 . It is well understood that the silane coupling agent 1108 can be any number of compounds depending on the desired replenishment of a surface organic group. The arrows entering and exiting the vapor exposure system 1100 further emphasize the in situ silane coupling agent deposition step (e.g., no external steps) and the simplicity with which wafer 1102 can be exposed to a silane coupling agent.
A wafer can also be exposed to a liquid silane coupling agent. Such an arrangement may include combining the silane coupling agent with any variety of basic organic solvents that would aid wafer and silane coupling agent interaction. A wafer could then be immersed in or otherwise exposed to the silane coupling agent solution. The liquid exposure may also be arranged in situ to avoid contamination and process flow interruptions potentially associated with an ex situ aqueous silane coupling agent exposure.
FIG. 12 illustrates a representative molecular portion of the amorphous passivated dielectric material. A passivated dielectric portion 1201 , including a pore 1202 , and coating 1203 are representative of the molecular composition of the replenished and passivated dielectric material surface. The passivated dielectric portion 1201 includes, as represented by their chemical or elemental composition, Si 1204 , O 1205 , CH 3 1206 , OH 1207 and A 1208 wherein A is an attached hydrocarbon side group specific to the silane coupling agent as characterized by the * in the Si—O—Si* bond. In general, each Si 1204 atom is bonded to four other atoms or molecules including but not limited to O 1205 , CH 3 1206 , OH 1207 , and A 1208 . It is important to note that for illustrative simplicity only, FIG. 12 shows the passivated dielectric portion 1201 as being geometric and repeating. However, in reality the passivated dielectric portion 1201 is amorphous. The bonds are strained and the overall geometry is imperfect. In an embodiment, the coating 1203 is hydrophobic, the benefits of which have been described with reference to FIGS. 3-10 .
As mentioned, the novel method of an embodiment of the invention passivates the surface of an interlayer dielectric and replenishes its surface organic groups through the same chemical reaction. However, the novel embodiment selectively passivates making the exposed interlayer dielectric hydrophobic while not interfering with the relative hydrophilic nature of the adjacent antireflective coating. Standard wet etch techniques, given the relative difference in surface energies of coated interlayer dielectric material and antireflective coating material, are highly selective. The result is a copper dual-damascene architecture, with properly intact critical dimensions, that utilizes a sufficiently low-k interlayer dielectric.
One skilled in the art will recognize the elegance of the disclosed embodiment in that it helps solve factors limiting the production use of leading-edge low-k dielectric materials, particularly porous silicon-containing dielectric materials, without adding ex situ steps or other complex manufacturing steps. The two benefits offered by an embodiment of the invention (e.g., porous, silicon-containing ILD surface carbon replenishment and passivation to make the surface more hydrophobic) can be completed in a single processing step, and can be easily duplicated for additional plasma etch steps and increasing numbers of interconnect levels.
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Processing problems associated with porous low-k dielectric materials are often severe. Exposure of low-k materials to plasma during feature etching, ashing, and priming steps has deleterious consequences. For porous, silicon-based low-k dielectric materials, the plasma depletes a surface organic group, raising the dielectric constant of the material. In the worst case, the damaged dielectric is destroyed during the wet etch removal of the antireflective coating in the via-first copper dual-damascene integration scheme. This issue is addressed by exposing the dielectric to silane coupling agents at various stages of etching and cleaning. Chemical reactions with the silane coupling agent both replenish the dielectric surface organic group and passivate the dielectric surface relative to the surface of the antireflective coating.
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PRIORITY
This application claims priority to an application entitled “Device and Method for Organizing a Menu in a Mobile Communication Terminal”, filed in the Korean Industrial Property Office on Sep. 9, 2002 and assigned Ser. No. 2002-54249, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a device and a method for organizing a menu in a mobile communication terminal, and more particularly to a device and a method for organizing a menu in a mobile communication terminal, which enables a user to create a desired menu by providing an algorithm for generation of multi-dimensional dynamic menu-planes and cursor movements there between.
2. Description of the Related Art
Currently, along with the development of technologies, a mobile communication terminal is provided with functions for using various services such as Internet service, short message service (SMS), and multimedia service, as well as the conventional audio communication service. Particularly, with a function for using multimedia or photograph service provided in the mobile communication terminal, a demand is sharply increasing for a color liquid crystal display. As use of such color mobile communication terminals spreads, interest in mobile user interface (hereinafter, referring to as “UI”) design is increasing.
A conventional mobile communication terminal generally has a main menu on the screen, which is composed of an icon array and a background animation, and in which movement between different menus and the menu's extension is diversely performed. A DIY (Do It Yourself) menu, which is a user-organizing menu applied to new models of mobile communication terminals, is also limited in both its functions and the usage range. The DIY menu enables the user to register menu items frequently used by the user from all menus available in the mobile communication terminal menus to create a user menu.
A currently available user menu enables a user to register his or her desired menu items in a predetermined number of previously-set icon boxes at desired positions, as well as to set icons for the registered user menu items.
FIG. 1 illustrates a user-setting menu screen in a conventional mobile communication terminal. For example, when 12 icon boxes are previously set in a user-setting menu, a user can set 12 menu items. Even when the user sets no user menu items, a default basic-slot menu configuration is provided and up/down/left/right movements of a cursor between the menu items are made using direction keys.
Referring to FIG. 1 , six menu icons of two rows and three columns are displayed on a screen 10 . A user may select his or her desired menu icons by moving a menu-selection box or a cursor using direction keys such as up/down/left/right keys. When the menu-selection box is positioned in a message-management menu icon 6 , a user must push the direction key at least three times in order to move the menu-selection box to a terminal-management menu icon 1 . In addition, in order to select menu icons not displayed on the screen 10 , a user must push a direction key, with the menu-selection box positioned in the menu icon 6 .
Thus, without using a short key, a large number of key manipulations are required for the user to move to another menu item or to a submenu registered as a lower hierarchical level, and although most people commonly use menus, there is no characteristic feature of the menus.
SUMMARY OF THE INVENTION
Therefore, the present invention has been designed in view of the above problem, and the present invention in one aspect provides a device and a method for organizing a menu in a mobile communication terminal that provides a user with an interesting dynamic menu display, thereby enabling quick menu-access to a high-level user. The menu may also include a three-dimensional effect, consequently improving the utilization of the menu.
In accordance with one embodiment of the present invention, the above and other objects are accomplished by a device for organizing a menu in a mobile communication terminal, comprising: a control unit for dynamically generating and deleting a plurality of menu planes according to a user's setting, each plane including thereon at least one menu item; a control unit for providing a mechanism of multi-dimensional navigation between the generated menu planes; and a display unit for receiving the menu planes from the control unit and displaying the received menu planes under control of the control unit.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features, and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 illustrates a user-setting menu screen in a general mobile communication terminal;
FIG. 2 is a block diagram illustrating a mobile communication terminal according to an embodiment of the present invention;
FIG. 3A illustrates a basic menu plane according to an embodiment of the present invention;
FIG. 3B illustrates inter-plane cursor movement according to the present invention;
FIG. 4 illustrates where a menu item is added according to an embodiment of the present invention;
FIG. 5 illustrates where there are three menu planes according to an embedment of the present invention;
FIG. 6 illustrates a high-level user menu mode according to an embodiment of the present invention; and
FIG. 7 is a flowchart illustrating a method of accessing a menu composed of multi-dimensional planes in a mobile communication terminal according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will be described in detail herein below with reference to the annexed drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.
A preferred embodiment of the present invention provides a basic menu plane enabling a user to easily select menu icons, a menu extension mechanism, a menu movement method, and a menu access mode for a high-level user.
FIG. 2 is a block diagram illustrating a mobile communication terminal according to an embodiment of the present invention. Referring to FIG. 2 , a control unit 100 controls the overall operation of the mobile communication. In addition, the control unit 100 forms a basic menu plane as will be described below in detail, and enables a display unit 140 to display the basic menu plane. Further, the control unit 100 dynamically generates or removes a menu plane each time a predetermined number of items, for example, four menu items are added or removed, respectively. When the user moves a menu selection box along menu icons so that the menu selection box moves from a first menu plane, displayed in the display unit 140 , to a second menu plane, the control unit 100 enables the display unit 140 to display a dynamic three-dimensional image, a moving hexahedron or other polyhedron that selectively includes first, second, third, . . . , etc. menu planes. That is, as illustrated in FIG. 3B , as the menu selection box moves from a first menu plane to a second menu plane, the hexahedron or other polyhedron rotates to show one menu plane initially and then another menu plane.
The display unit 140 displays various messages, etc., under the control of the control unit 100 . For example, the display unit 140 is a LCD (Liquid Crystal Display), or TFT (Thin Film Transistor) LCD. An interface unit 120 includes a plurality of number and function keys, and transmits input data, corresponding to a key selected by a user, to the control unit 100 . For example, the interface unit 120 may include up/down/left/right arrow keys for enabling movement of the menu selection box in the basic menu plane displayed on the screen of the display unit as described above. Such an interface unit 120 may include a commonly used key matrix or touch screen. When the interface unit 120 is embodied with a touch screen, a plurality of number keys, function keys, and arrow keys, etc., displayed on the touch screen, may be selected by an input instrument such as a stylus pen.
FIG. 3A is a view illustrating a basic menu plane, and FIG. 3B is a view illustrating a cursor movement between menu planes displayed in the display unit. Referring to FIGS. 3A and 3B , the basic menu plane 210 has a rectangular image, equally divided into 9 parts, for example, that is displayed when the user pushes a menu key. A basic menu plane 210 includes a menu icon box 215 positioned in the center, and four user menu registration slots 212 , 214 , 216 , and 218 to which the menu selection box can move from the menu icon box 215 by selecting or pushing a key once. A menu icon is disposed in each of the user menu registration slots 212 , 214 , 216 , and 218 . The control unit 100 disposes a management menu item of mobile communication terminal in the menu icon box 215 in the center. A management menu in the menu icon box 215 includes submenus for defining functions related to a user-menu setting such as user menu registering, removing, and moving functions, changing icons, and changing of a menu item name. The management menu is referred to as a terminal management menu. In addition, the terminal management menu may further include a function of setting high/low-level user modes. A user menu may be added, for example, in a start-menu registration portion of the terminal management menu, and may be deleted in a start-menu deletion portion thereof. In addition, the user menu icons may be changed, for example, in a main-screen setting portion thereof.
Menu registration icon boxes in the basic menu plane 210 , which can be set by a user, comprise four user menu registration slots 212 , 214 , 216 , and 218 to which the menu selection box can move from the menu icon box 215 by selecting or pushing a key once. Accordingly, as the number of menu items registered by the user exceeds 4, a new menu plane is generated. A menu item in the center of the new menu plane also becomes the terminal management menu item. Also, when a number of new menu planes are generated, the terminal management menu is always positioned in their menu registration slot in the center. Further, the control unit 100 generates or removes a menu plane dynamically each time four menu items are added or removed. In addition, the control unit 100 enables the user to move the menu selection box from one menu plane to other menu plane using a direction key or a menu key. In detail, provided that the menu selection box or a curser is positioned at one of the user menu registration slots 212 , 214 , 216 and 218 shown in FIG. 3A , selecting or pressing a direction key from the menu slot where the cursor is positioned enables movement of the cursor to another menu plane. For example, if the up arrow key is pushed when a cursor is positioned on the user menu registration slot 212 of a menu plane 210 , then the cursor moves to the menu registration slot 228 of the menu plane 220 . If the right arrow key is pushed when the cursor is positioned on the user menu registration slot 216 of the menu plain 210 , then the cursor moves to the menu registration slot 224 of a menu plain 220 .
Referring to FIG. 3A , if a user pushes the up arrow key when a user cursor is positioned on the user menu registration slot 212 of the basic menu plain 210 , then the menu plain 220 is displayed on the screen of the display unit 140 . Herein, the cursor is basically positioned on the lower menu slot 228 of the menu plain 220 in case of moving to the menu plain 220 from the user menu registration slot 212 previously positioned. If there is no registered menu in the menu slot 220 , then the cursor is positioned on the menu icon box 225 of the menu plain 220 .
Here, when the cursor or the menu selection box moves from one menu plane to another menu plane, an upper one 212 of four menu registration slots of said one menu plane 210 is connected to a lower one 228 of four menu registration slots of said another menu plane 220 . In addition, a lower one 218 of the four menu registration slots of said one menu plane 210 is connected to an upper one (it is not shown in FIG. 3 ) of the four menu registration slots of said another menu plane, and a left one 214 of the four menu registration slots of said one menu plane 210 is connected to a right one (it is not shown in FIG. 3A ) of the four menu registration slots of said another menu plane. Finally, a right one 216 of the four menu registration slots of said one menu plane 210 is connected to a left one 224 of the four menu registration slots of said another menu plane 220 . That is, the menu is configured as if a number of menu planes are spatially connected to each other. Actually, the connection is made within the user's thought, not the real space. In detail, the position of the menu planes is not specified in real space, but the position of the next or subsequent menu plane is determined according to the user's thought process. Further detail regarding the menu item connections will be described with reference to FIGS. 4 and 5 hereinafter.
Here, if there is no menu item registered in the menu registration slot in said another menu plane, connected to the menu registration slot in said one menu plane, the cursor or the menu selection box moves from the menu registration slot in said one menu plane to a terminal management menu in the center of said another menu plane.
If there is no registered menu in the menu slot where the cursor is to be positioned and the previous menu plain is continued upon a cursor moving from the basic menu plain to one of other menu plains by a key input of a user according to the above-mentioned movement rule, then the cursor is positioned on the menu icon box 215 in order to reduce the unnecessary key input.
In addition, in response to the inter-plane cursor movement, the control unit 100 enables the display unit 140 to display a rotating three-dimensional image, a hexahedron or other polyhedron including one menu plane and another menu plane, such that its front view is changed from said one menu plane to said another menu plane as illustrated in FIG. 3B .
In a preferred embodiment, the maximum number of menu items in one menu plane, which can be registered by a user, is four. If the user registers an additional menu item, with four menu items previously registered by the user, the control unit 100 generates a new menu plane internally, and registers the additional menu item. Here, the number of the additional menu item registered by the control unit 100 is one. However, when the user moves the cursor to the new menu plane using the direction key, the control unit 100 enables the new menu plane to inherit three menu items from said one menu plane, besides the one additional menu item. That is, when there are empty menu slots in the new menu plane, in which no menu item is registered, the control unit 100 displays the menu items in the previous menu plane corresponding to the empty menu slots in position in the empty menu slots. The menu item's inheritance is to give the user a further chance to select a menu rather than keep the empty menu slots as they are, thereby reducing unnecessary movements of the cursor. According to the present invention, there is no limit on the maximum number of menu planes. However, when permitting a short key access by using number keys provided in the mobile communication for the user's convenience, it may be preferable to set the maximum number of the menu planes to three.
According to the present invention, in one embodiment, the control unit 100 may dispose four basic menu items as a default in the first menu plane. In addition, a user may change the default menu items to other menu items, but not delete them. This limitation on the deletion is to provide the user with at least one menu plane when the user pushes the menu key, consequently providing the user with complete GUI service and basic accessibility to the menu functions.
In this case, when a user adds a new menu item to the existing menu items, the control unit 100 automatically generates a new menu plane, and registers the new menu item to the new menu plane. It is to be noted that newly added menu items are registered in each menu plane in sequence of menu slots 212 → 214 → 216 → 218 , referring to FIG. 3A . In one embodiment, when there are three menu planes, the maximum number of menu items that may be registered is twelve, and access to each menu item may be made by using a number key corresponding to a number assigned to each menu item.
FIG. 4 illustrates where a menu item is added according to an embodiment the present invention, and FIG. 5 illustrates where there are three menu planes according to an embodiment of the present invention.
Referring to FIGS. 2 to 5 , the control unit 100 enables a user to register, delete, and change a user menu in a terminal management menu positioned in the center of the menu plane. When the user registers a new menu in the terminal management menu, a new menu plane is generated internally, and the registered menu item is placed in the upper menu slot of the second menu plane. For example, when additional menu items are registered (for example, menu 9 ) after finishing the registration up to a menu 8 on menu plane 2 220 , the control unit 100 generates a new menu plane 3 as indicated by numeral 230 in FIG. 5 , and enables its empty menu slots to inherit the corresponding ones from the menu plane 2 220 . When a menu item in any position is deleted, the control unit 100 automatically realigns the menu items of each menu plane, and removes an unnecessary menu plane by the menu plane's deletion.
When there is no menu item additionally registered by the user in the menu plane 1 210 , the cursor movement between menus occur in this menu plane only. In a case where a user registers an additional menu to generate the menu plane 2 220 , the user may move a cursor to the menu plane 2 220 by pushing a direction key from the menu plane 1 210 . When, upon moving from the menu plane 1 210 to the menu plane 2 220 , there is no menu item in the new position, the new position inherits the corresponding menu item from the previous menu plane as shown in FIG. 4 , and the cursor is placed in the terminal management box in the center. On the other hand, if there is a registered menu item in the new menu plane, the cursor is placed in the registered menu item.
When three menu planes are formed as illustrated in FIG. 5 , when the user moves a cursor from the “menu 2 ” to “menu 7 ”, a cursor movement back to the previous menu plane is allowable through “menu 7 ”. That is, when a cursor movement is made between menu planes, the cursor movement's path is stored in a memory in the mobile communication terminal, so that a user may move a cursor between the menu planes along the path.
In FIG. 5 , if a user pushes the left arrow key when the cursor is positioned on Menu 2 of the menu plain 210 and the cursor moves to the menu plain 220 , then the cursor is to be positioned on Menu 7 of the menu plain 220 . Herein, the Menu 7 of the menu plain 220 is a menu slot connected to the previous menu plain 210 . Such a menu slot connected to other menu plain is referred to as entry point. The menu slots of the entry point are varied on the number of menu plain. If the right arrow key is pushed in Menu 7 , the cursor moves to the menu plain 210 . And, in movement of the cursor by a direction key at the remaining menu slots Menu 5 , Menu 6 and Menu 8 of the menu plain 220 , if there is a menu plain other than the menu plain 210 , the cursor moves to the menu plain. For example, in FIG. 5 , the cursor positioned on Menu 5 , Menu 6 and Menu 8 moves to other menu plain, i.e., the menu plain 230 . However, if there is no menu plain 230 and there is only two menu plains 210 and 220 , the cursor should move only to the menu plain 210 from the menu plain 220 .
Selecting any one of direction keys with the cursor placed on a menu item in the menu plane 2 220 , other than the right direction key at “menu 7 ”, moves a cursor to a new menu plane, i.e., a menu plane 3 230 . Similarly, selecting any one of direction keys with the cursor placed on a menu item in the menu plane 3 230 , other than the right direction key at “menu 11 ”, moves a cursor to the menu plane 1 210 . Subsequent operations are performed in the same manner. When a user pushes the menu key the first time, no previous menu plane exists, and therefore all the next planes become the menu plane 2 220 . However, when the user continues to push the direction key, reentering the menu plane 1 210 through the menu plane 3 230 , the user enables a cursor to move to the menu plane 3 230 through an entry point or the menu plane 2 220 .
FIG. 6 is a view illustrating a high-level user menu mode according to the present invention.
The present invention, in one embodiment, provides a high-level user menu mode in a terminal management menu. This high-level user menu mode is configured by a combination of the menu key and the direction key, which enables both a cursor movement between the planes and selection of the menu items. That is, when a mobile communication terminal has key arrays as illustrated in FIG. 6 , a user may display a menu screen by pushing a “Menu” key in a standby state. In the high-level user mode, the “Menu” key is used for the inter-plane cursor movements. In addition, four direction keys 1, 2, 3, 4 are mapped to four menu items in the corresponding positions, respectively, and a key in the center corresponds to a terminal management menu 5 . In this case, a user may perform an inter-plane cursor movement by selecting the menu key once, and activate the menu items using the corresponding direction keys.
FIG. 7 is a flowchart illustrating a method of accessing a menu composed of multi-dimensional planes in a mobile communication terminal according to one embodiment of the present invention, for example, when a user selects a user-setting menu.
When a user registers user menus that include frequently used menus from all menus in the mobile communication terminal, multi-dimensional menu planes are generated as described above, and the user may access the menu according to a control flow as shown in FIG. 7 .
Referring to FIG. 7 , when a user selects a user-setting menu in a mobile communication terminal, the control unit 100 thereof waits for a key input from the user in step 302 . When the control unit 100 receives the key input from the user through an interface unit 120 in step 304 , the control unit 100 moves to step 306 . Here, the interface unit 120 may be a key matrix or a touch screen as mentioned above. Then, the control unit 100 checks if the key selected by the user in step 306 is, for example, one of the up/down/left/right direction keys. When the key selected by the user is the direction key, the control unit 100 moves to step 308 to determine whether the cursor movement made by the direction key is inside the menu plane. That is, the control unit 100 determines whether the user's selection of the direction key moves the menu selection cursor on the menu plane out of the menu plane. When it is determined that the menu selection cursor moves to a menu item in the menu plane, the control unit 100 moves to step 310 to place the menu selection cursor at the menu item.
When it is determined that the menu selection cursor moves out of the menu plane, the control unit 100 moves to step 312 to check if there is a next menu plane. When it is checked that there is no next menu plane, the control unit 100 moves to step 314 to move the menu selection cursor to a menu slot at a position opposite to its present position in the menu plane, and returns to step 302 to wait for a key input from the user.
If it is determined that there is a next menu plane, the control unit 100 moves to step 316 to display the next menu plane on the display unit 140 , and moves the menu selection cursor to the next menu plane. Then, in step 318 , the control unit 100 determines whether menus are registered in all menu slots in the next menu plane. If it is determined that there is an empty menu slot, to which no menu item is registered, in step 324 , the control unit 100 enables the empty menu slot, currently on display, to inherit the corresponding menu item from the previous menu plane. For example, when there are three empty menu items in the next menu plane as mentioned above, the empty menu items automatically inherit the corresponding menu items from the previous menu plane, respectively. This inheritance operation is to give the user a further chance to select a menu rather than keep the empty menu slots as they are, thereby eliminating a need to go back to the previous menu plane to access these menu items and thus reducing unnecessary key manipulations. Then, in step 320 , the control unit 100 determines whether a menu item to be reached by the menu selection cursor is the inherited menu item. If it is determined that the menu item is the inherited menu item, the control unit 100 positions the menu selection at the terminal menu item on the display in step 32 and if not, positions it at the corresponding menu item.
The present invention revolutionizes the common menu configuration in the prior art, and provides a diversified menu constitution and a multi-dimensional cursor movement between menu planes, and various ways of accessing the menu, consequently improving the utilization and practical use of the menu.
Although various embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
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A device for organizing a menu in a mobile communication terminal. The device comprises a control unit for dynamically generating and deleting a plurality of menu planes according to a user's setting, each plane including at least one menu item; a control unit for providing a mechanism of multi-dimensional navigation between the generated menu planes; and a display unit for receiving the menu planes from the control unit and displaying the received menu planes under control of the control unit.
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CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present patent application/patent is a continuation-in-part (CIP) of copending U.S. patent application Ser. No. 14/748,413, filed on Jun. 24, 2015, and entitled “METHODS AND SYSTEMS FOR INCREASING THE CARBON CONTENT OF SPONGE IRON IN A REDUCTION FURNACE,” the contents of which are incorporated in full by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates generally to methods and systems for increasing the carbon content of sponge iron in a direct reduction (DR) furnace.
BACKGROUND OF THE INVENTION
[0003] Direct reduced iron (DRI), which is also referred to as sponge iron, is typically produced by the reaction of iron ore in a reactive gas stream containing reducing agents, such as H 2 and CO, in a moving bed or vertical shaft reactor. The following are the equilibrium-limited global reactions:
[0000] Fe 2 O 3 +3H 2 2Fe+3H 2 O (1)
[0000] Fe 2 O 3 +3CO 2Fe+3CO 2 (2)
[0004] In commercial DR processes, the product DRI still contains unreacted iron oxide, which may be as high as 15.0% by weight. Due to the equilibrium-limited nature of reactions (1) and (2), it is not economical to achieve complete (i.e. 100.0%) reduction within the reduction reactor. In fact, when the degree of reduction approaches 100.0%, an excessively long residence time inside the reduction reactor is required to remove the remaining oxygen from the partially reacted material. While the rate of reduction reactions can be increased to some extent by increasing temperature, such temperature increases are limited by the fact that the operating temperature must be kept below the sintering temperature so that clusters are not formed inside the reduction reactor. Thus, the typical reduction is maintained somewhere in the 85.0-95.0% range at the discharge of conventional commercial reduction reactors, depending on the quality of the oxide material and plant operating conditions.
[0005] Such product DRI can be used as a source of low-residual iron, in addition to ferrous scrap and pig iron in the production of steel, mainly through an electric arc furnace (EAF) in a steelmaking facility. The EAF melts that charged material by means of an electric arc, typically accompanied by the injection of oxygen in order to burn impurity carbon and Fe 3 C, if any. The partial or complete combustion of the carbon with oxygen provides a uniform internal source of energy for the EAF when the oxygen is injected into the EAF. Furthermore, the conversion of Fe 3 C into iron and carbon is an exothermic reaction, which improves the thermal efficiency of the EAF. Therefore, the carbon content of the DRI can be interpreted as an energy source, and this energy is finally utilized in the EAF when the DRI is melted.
[0006] Although other carbon sources, like coal or rubber, can be added to the EAF for the same purpose, the resulting yield is significantly less than the combined carbon in the DRI, due to particle blow-off and impurities in the carbon sources. Therefore, it is highly desirable to increase the carbon content of DRI during the reduction step before discharging it into the EAF.
[0007] Inside the reduction reactor, carbon can be generated (i.e. physical carbon—C) or added to the DRI (i.e. chemical carbon—Fe 3 C) through the following global reactions:
[0000] 3Fe+CO+H 2 Fe 3 C+H 2 O (3)
[0000] 3Fe+2CO Fe 3 C+CO 2 (4)
[0000] 3Fe+CH 4 Fe 3 C+2H 2 (5)
[0000] CO+H 2 C+H 2 O (6)
[0000] 2CO C+CO 2 (7)
[0000] CH 4 C+2H 2 (8)
[0008] Therefore, two major sources of combined carbon in product DRI (i.e. physical and chemical) are CO and hydrocarbons (e.g. CH 4 ) in the reducing gas stream. While the amount of CO in the reducing gas stream is normally set by the operating conditions of the reducing gas generation unit, the amount of hydrocarbons is adjusted by the operator to suppress methanation reactions inside the reduction furnace, while considering the cooling effects caused by:
Endothermic reactions (5) and (8) above, Endothermic reforming reactions catalyzed by iron within the reduction reactor, Direct heat removal by the hydrocarbons, which have noticeably higher heat capacities as compared to most of the gases in a DR plant, and Limited preheat temperatures for hydrocarbon streams (below ˜400 degrees C.).
In other words, from an operational point of view, there are limitations to increase the amounts of CO and CH 4 in the reducing gas stream.
[0013] One of the commercially practiced approaches for bypassing these limitations is the addition of a hydrocarbon-rich stream to the bulk of the already reduced materials. This is usually done by injecting natural gas into the hot reduced material (a good catalyst) once it leaves the reduction zone—a region typically called the transition zone. Thus, due to cracking reactions in the transition zone, the carbon content of the product increases.
[0014] Due to the endothermic nature of the cracking reactions, this interaction lowers the material and gas temperatures, thus helping to cool the product DRI. However, this cooling effect for plants where the DRI has to leave the reduction furnace at elevated temperatures, is viewed as a negative side effect, and is typically minimized.
[0015] In commercialized DR processes, a hydrocarbon source is normally utilized to produce the reducing agents via a catalytic or non-catalytic reforming process. For catalytic reforming processes, the required oxidants are typically H 2 O (i.e. steam) and CO 2 . For non-catalytic reforming processes, the required oxidant is typically oxygen (O 2 ). In the latter case, very fast partial and complete combustion reactions generate H 2 O and CO 2 for further homogeneous and/or heterogenous reforming reactions. All reforming processes convert some portion of the carbon and hydrogen contents of the hydrocarbons into CO and H 2 , respectively. For instance, in the case of CH 4 being the only hydrocarbon source, the global reaction schemes governing the homogenous and heterogenous reforming processes are:
[0000] CH 4 +2O 2 CO 2 +2H 2 O (9)
[0000] CH 4 +1.5O 2 CO+2H 2 O (10)
[0000] CH 4 +O 2 CO+H 2 +H 2 O (11)
[0000] CH 4 +0.5O 2 CO+2H 2 (12)
[0000] CH 4 +H 2 O CO+3H 2 (13)
[0000] CH 4 +CO 2 2CO+2H 2 (14)
[0000] The gas leaving the reforming process is therefore a mixture of CO, H 2 , and unreacted hydrocarbons and oxidants, and is called the reformed gas.
[0016] Alongside these main reactions, depending on the thermodynamics of the system, some of the previously mentioned reactions can also occur, the major of which are:
[0000] CO+H 2 C+H 2 O (6)
[0000] 2CO C+CO 2 (7)
[0000] CH 4 C+2H 2 (8)
[0000] The resulting carbon from these side reactions creates detrimental consequences for the reforming catalyst, and, therefore, it is a common practice to prevent their occurrence by controlling the operating parameters of the reformer unit.
[0017] Based on reactions (1) and (2), the presence of oxidants H 2 O and CO 2 in the reducing gas mixture reduces the efficiency of the reduction reactions. Consequently, operating parameters in the reforming section of the plant are adjusted in such a way that the reformed gas has high values of CO/CO 2 and H 2 /H 2 O, which can be achieved by a high conversion rate for CH 4 , while maintaining the concentrations of H 2 O and CO 2 to the lowest extent possible in the feed gas to the reforming unit. Typically, CH 4 slip from the reformer unit is maintained below ˜1.0-2.0%, and, as a result, similar to CO/CO 2 and H 2 /H 2 O, the H 2 /CH 4 ratio in the reformed gas stream is high. While a high CO/CO 2 ratio in the reformed gas stream favors carbon deposition inside the reduction reactor according to reactions (4) and (7), a high H 2 /CH 4 ratio diminishes the chance of carbon deposition according to reactions (5) and (8). Thus, it is clear that by increasing the CO/CO 2 ratio, the carburization potential of the reformed gas improves. This is the main focus of the present invention.
BRIEF SUMMARY OF THE INVENTION
[0018] The present invention makes use of industrially available technologies, i.e. membrane modules (organic/inorganic/organometallic) by which a majority of the hydrogen and or CO 2 are recovered from a reformed gas stream in a plant via the rejection (i.e. separation) of other components. Such separation typically results in two different streams with distinct chemical compositions: one rich in CO and the other rich in H 2 . The H 2 -rich gas stream then blends with different gas streams in the process, including, but not limited to, the feed gas stream to the reformer unit, the cooling gas stream, the reducing gas stream, the fuel gas streams, etc. The CO-rich gas stream flows into the transition zone and/or the cooling zone of the reduction furnace to increase the carbon content of the sponge iron. The exothermic nature of reactions (4) and (7) permits the addition of more gas into the transition zone to keep the temperature high. Optionally, a hydrocarbon-rich gas stream is blended with the CO-rich gas stream prior to the final injection port.
[0019] Hundreds of membrane modules have been installed around the world by different vendors in oil refineries and petrochemical plants, where the recovery of hydrogen, the separation of CO 2 , or the adjustment of the H 2 /CO ratio is important for the efficient operation of the plant. Thus, there is little impediment to employing such equipment in a novel manner in a DR plant.
[0020] The present invention is not limited to the use of membrane modules. All other separation/adsorption technologies (e.g. pressure/vacuum pressure/temperature swing adsorption (PSA/VPSA/TSA) units) meeting process requirements can be used to accomplish the carburization task of the present invention based on the guidelines presented.
[0021] In one exemplary embodiment, the present invention provides a method for producing direct reduced iron having increased carbon content, comprising: providing a reformed gas stream from a reformer; delivering the reformed gas stream to a carbon monoxide recovery unit to form a carbon monoxide-rich gas stream and a hydrogen-rich gas stream; and delivering the carbon monoxide-rich gas stream to a direct reduction furnace and exposing partially or completely reduced iron oxide to the carbon monoxide-rich gas stream to increase the carbon content of resulting direct reduced iron. The carbon monoxide-rich gas stream is delivered to one of a transition zone and a cooling zone of the direct reduction furnace. The reformed gas stream, generated in a tubular catalytic reformer in direct reduction plants, typically comprises 50.0-80.0% H 2 , 20.0-40.0% CO, 1.0-5.0% CO 2 , 0.0-3.0% CH 4 , and 0.0-5.0% N 2 , all dry bases, depending on the operating conditions of the reformer. The method further comprises cooling the reformed gas stream to less than its saturation temperature, preferably ambient temperature, e.g. 20-50 degrees C. in a cooler/chiller. The method further comprises compressing the reformed gas stream to a pressure of 5.0-20.0 barg, preferably 10.0-15.0 barg, in a single or multi-stage compressor set before flowing into the CO recovery unit. In order to have a better efficiency, the carbon monoxide-rich gas stream leaving the CO recovery unit should comprise more than 60.0% carbon monoxide, preferably between 70.0-90.0%. The method further comprises recycling the hydrogen-rich gas stream for use in a direct reduction plant for different potential applications, including, but not limited to, fuel for combustion applications, feed gas to the reformer, and reducing gas to the reduction furnace. In the case of using the hydrogen-rich stream as a fuel, it reduces the amount of CO 2 released to atmosphere. The method further comprises mixing the carbon monoxide-rich gas stream with a hydrocarbon-rich gas stream, preferably natural gas, to form the final carburizing gas.
[0022] The hydrocarbon-rich gas stream should comprise more than 80.0% hydrocarbon. Optionally, depending on the chemical composition of the hydrocarbon-rich gas stream, the method comprises one or more of a dehumidifier and a mist-eliminator/saturator for reducing the humidity of the hydrocarbon-rich gas stream to below 1.0%, and preferably dry it. Optionally, depending on the chemical composition of the hydrocarbon-rich gas stream, the method comprises one desulfurization step to drop the sulfur content of the hydrocarbon-rich stream to less than 100 ppm, preferably to less than 10 ppm. Optionally, depending on the mixing ratio between the hydrocarbon-rich stream and CO-rich stream, the system comprises a preheater for elevating the temperature of the final carburizing gas to a temperature of not more than 400 degrees C., preferably somewhere between 50 and 300 degrees C. The method further comprises injection of the final carburizing gas onto the bulk of the already reduced materials inside the reduction reactor.
[0023] In another exemplary embodiment, the present invention provides a method for producing direct reduced iron having increased carbon content, comprising: providing a carbon monoxide-rich gas stream; and delivering the carbon-monoxide-rich gas stream to a direct reduction furnace and exposing partially or completely reduced iron oxide to the carbon monoxide-rich gas stream to increase the carbon content of resulting direct reduced iron. The carbon monoxide rich gas stream delivered to the direct reduction furnace comprises at least 60% CO prior to being mixed with any other gas stream. The carbon monoxide-rich gas stream is delivered to one or more of a transition zone and a cooling zone of the direct reduction furnace. Optionally, providing the carbon monoxide-rich gas stream comprises initially providing one of a reformed gas stream from a reformer (such as a catalytic reformer (for example, a tubular reformer), a non-catalytic reformer (for example, a partial oxidation reactor), or a combination reformer (for example, an auto-thermal reformer or a two-stage reformer) and a syngas stream from a syngas source (such as a gasifier, a coke oven gas source, or a blast furnace). Optionally, the carbon monoxide-rich gas stream is derived, at least in part, from a carbon monoxide recovery unit that forms the carbon monoxide-rich gas stream and an effluent gas stream. The carbon monoxide rich gas stream leaving the carbon monoxide recovery unit comprises at least 60% CO. Optionally, the carbon monoxide recovery unit is operated in parallel with a bypass line, the carbon monoxide recovery unit and the bypass line each providing a portion of the carbon monoxide-rich gas stream. Optionally, the method also includes recycling the effluent gas stream for use in a direct reduction plant. Optionally, the method further includes providing a hydrocarbon-rich gas stream to the direct reduction furnace with the carbon monoxide-rich gas stream. Optionally, the method still further includes providing a hydrocarbon-rich gas stream to one or more of a transition zone and a cooling zone of the direct reduction furnace.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers are used to denote like method steps/system components, as appropriate, and in which:
[0025] FIG. 1 is a schematic diagram illustrating one exemplary embodiment of the process for increasing the carbon content of sponge iron by injecting a carbon monoxide-rich stream into a reduction furnace of the present invention;
[0026] FIG. 2 is a schematic diagram illustrating another exemplary embodiment of the process for increasing the carbon content of sponge iron in a reduction furnace of the present invention, where a hydrocarbon-rich stream, with or without adjustment of its moisture and sulfur content, is blended with the carbon monoxide-rich stream of FIG. 1 ; and
[0027] FIG. 3 is a schematic diagram illustrating a further exemplary embodiment of the process for increasing the carbon content of sponge iron in a reduction furnace of the present invention, optionally where a carbon monoxide recovery unit bypass is utilized, optionally utilizing reformer or other syngas source, and optionally where a hydrocarbon-rich stream, with or without adjustment of its moisture and sulfur content, is blended with the carbon monoxide-rich stream of FIGS. 1 and 2 and/or delivered directly to the transition zone and/or cooling zone of the reduction furnace.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The present invention provides an efficient and cost effective process for increasing the carbon content of DRI in a DR plant. It provides a carbon monoxide-rich stream with limited impurities that is directly injected into the bulk of hot and partially or completely reduced materials inside the reduction furnace, or first blended with other gases (e.g. a hydrocarbon-rich gas stream). The combination of coking reactions noticeably increases the carbon content of the resulting DRI, while keeping the temperature of the bulk high.
[0029] For a DR plant utilizing a reforming step, of any type, the following are the main advantages:
The design is simple and straightforward with respect to engineering, construction, and operation. The conventional method of injecting a hydrocarbon-rich stream into the reduction furnace increases the carbon content of the material by endothermic hydrocarbon cracking reactions; hence lowering the material temperature. The present invention, however, boosts the carbon content of the iron via an exothermic reaction that keeps the reduction zone hot, yielding improved plant productivity. This is a plus for DR plants producing hot-discharged DRI. The process utilizes relatively little equipment. The process can be incorporated into either cold or hot-discharged DRI plants. Various vendors have already commercialized the individual components utilized, and their design and operation in other contexts are well documented. The required CAPEX and OPEX for the proposed system are reasonable. Integrating the present invention into existing DR plants does not affect the normal operation of such plants. The design can be added as a supplemental plug-in package for existing DR plants. There is no combustion/reaction associated with the design. Thus, its operation is quite safe and reliable.
[0039] Referring now specifically to FIG. 1 , in one exemplary embodiment, the process 5 of the present invention includes cooling at least a portion of the reformed gas derived from a reformer unit 10 of any design (such as a catalytic reformer (for example, a tubular reformer), a non-catalytic reformer (for example, a partial oxidation reactor), or a combination reformer (for example, an auto-thermal reformer or a two-stage reformer), or any other reducing gas generating unit capable of producing a CO-containing gas with a relatively high CO/CO 2 ratio) to close to ambient temperature (e.g. 30 degrees C.) using a cooler/chiller 14 . Preferably, the reformed gas stream 12 contains at least 20.0% CO. The cooler/chiller 14 can utilize direct contact cooling, indirect contact cooling, refrigeration cooling, etc. During the cooling step, reformed gas will lose some of its water content, which in turn improves the carburization potential of the reformed gas. The cool/dry reformed gas optionally flows through a compressor 16 that boosts its pressure (to e.g. 15 barg), as most separation/adsorption methods works best at higher pressures. During the compression step, the gas loses even more water, resulting in further improved carburization potential.
[0040] The compressed gas, after optional temperature adjustment, flows into a system of membrane modules 18 for CO recovery. Any other kind of CO recovery mechanism can also be used for this step, like PSA/VPSA/TSA, refrigeration, etc. Following this step, the CO-rich gas stream 20 contains more than 60.0% CO, while the H 2 -rich gas stream 22 may contain more than 70.0% H 2 correspondingly.
[0041] The CO-rich gas stream 20 coming from the CO recovery unit 18 is optionally passed through a preheater 26 , which heats it to 50-300 degrees C. The CO-rich gas stream 20 is then introduced into the DR furnace 28 below the primary reduction zone 30 (e.g. into the transition zone 32 and/or the cooling zone 34 ), where the CO-rich gas stream 20 comes into contact with partially or completely reduced iron oxide and deposits carbon based on the well known reactions 2CO C+CO 2 and 3Fe+2CO Fe 3 C+CO 2 . In general, the partially or completely reduced iron oxide in the transition zone 32 and/or the cooling zone 34 contains 0.0%-3.0% combined carbon before, and up to 4.5% combined carbon after the CO-rich stream addition.
[0042] Further, the rejected gas 22 from the CO recovery unit 18 (rich in H 2 ) can be used in different portions of the DR plant as fuel, cooling gas, syngas, or process gas, or it can be exported to another facility.
[0043] Referring to FIG. 2 , in another exemplary embodiment the process 7 of the present invention includes cooling at least a portion of the reformed gas derived from a reformer unit 10 of any design (such as a catalytic reformer (for example, a tubular reformer), a non-catalytic reformer (for example, a partial oxidation reactor), or a combination reformer (for example, an auto-thermal reformer or a two-stage reformer), or any other reducing gas generating unit capable of producing a CO-containing gas with a relatively high CO/CO 2 ratio) to close to ambient temperature (e.g. 30 degrees C.) using a cooler/chiller 14 . Preferably, the reformed gas stream 12 contains at least 20.0% CO. The cooler/chiller 14 can utilize direct contact cooling, indirect contact cooling, refrigeration cooling, etc. During the cooling step, reformed gas will lose some of its water content, which in turn improves the carburization potential of the reformed gas. The cool/dry reformed gas optionally flows through a compressor 16 that boosts its pressure (to e.g. 15 barg), as most separation/adsorption methods works best at higher pressures. During the compression step, the gas loses even more water, resulting in further improved carburization potential.
[0044] The compressed gas, after optional temperature adjustment, flows into a system of membrane modules 18 for CO recovery. Any other kind of CO recovery mechanism can also be used for this step, like PSA/VPSA/TSA, refrigeration, etc. Following this step, the CO-rich gas stream 20 contains more than 60.0% CO, while the H 2 -rich gas stream 22 may contain more than 70.0% H 2 correspondingly.
[0045] The rejected gas 22 from the CO recovery unit 18 (rich in H 2 ) can be used in different portions of the DR plant as fuel, cooling gas, syngas, or process gas, or it can be exported to another facility.
[0046] Further, a hydrocarbon-rich gas stream 36 (natural gas, for example) is blended with the CO-rich gas stream 20 in a mixer 24 before both are introduced into the DR furnace 28 . Optionally, if the hydrocarbon-rich stream is wet, one or more dehumidification units 38 can be used to make the gas dry for suppressing decarburization reactions. Optionally, if the hydrocarbon-rich stream is loaded with significant amount of sulfur compounds, one desulfurization unit 40 can be used to decrease and control the amount of total sulfur below 100 ppm, preferably, below 10 ppm, before flowing into the reduction furnace. In this case, the preheater 26 can be used to preheat the hydrocarbon-rich gas stream 36 prior to mixing the hydrocarbon-rich gas stream 36 with the CO-rich gas stream 20 in the mixer 24 , and at a different temperature (e.g. about 350-400 degrees C.), such that soot formation is minimized as compared to preheating after the mixer 24 at a temperature of about 50-300 degrees C. Thus, the preheater 26 can alternatively be disposed before or after the mixer 24 in all embodiments.
[0047] Thus again, the present invention makes use of industrially available technologies, i.e. membrane module units (organic/organic/organometallic) by which a majority of the hydrogen and or CO 2 are recovered from a reformed gas stream in a plant via the rejection (i.e. separation) of other components. Such separation typically results in two different streams with distinct chemical compositions: one rich in CO and the other rich in H 2 . The H 2 -rich gas stream then blends with different gas streams in the process, including, but not limited to, the feed gas stream to the reformer unit, the cooling gas stream, the reducing gas stream, the fuel gas stream, etc. The CO-rich gas stream flows into the transition zone and/or the cooling zone of the reduction furnace to increase the carbon content of the sponge iron. The exothermic nature of reactions (4) and (7) above permits the addition of more gas into the transition zone to keep the temperature high. Optionally, a hydrocarbon-rich gas stream is blended with the CO-rich gas stream prior to the final injection port.
[0048] Hundreds of membrane modules have been installed around the world by different vendors in oil refineries and petrochemical plants, where the recovery of hydrogen, the separation of CO 2 , or the adjustment of the H 2 /CO ratio is important for the efficient operation of the plant. Thus, there is little impediment to employing such equipment in a novel manner in a DR plant.
[0049] The present invention is not limited to the use of membrane modules. All other separation/adsorption technologies (e.g. pressure/vacuum or pressure/temperature swing adsorption (PSA/VPSA/TSA) units) meeting process requirements can be used to accomplish the carburization task of the present invention based on the guidelines presented.
[0050] FIG. 3 provides further refinements to the process 9 of the present invention. Optionally, the CO recovery unit 18 can be bypassed, in part or in whole, via a bypass line 50 . A 30-60% bypass is the most likely scenario. However, lower or higher percentages are possible, anywhere from 0-100%, depending on the chemical composition of the reformed gas or syngas. If a 100% bypass is employed, then the compressor 16 can operate at about 2-7 barg, as opposed to 10-15 barg. However, if a 100% bypass is employed, then a drying unit (not illustrated) can be included along the bypass line 50 . Optionally, the reformer 10 and reformed gas 12 (and the related components) can be replaced with gas from a coal gasifier or the like. It should be noted that the reformer 10 can be a catalytic reformer (for example, a tubular reformer), a non-catalytic reformer (for example, a partial oxidation reformer), or a combination reformer (for example, an auto-thermal reformer or two-stage reformer). The coal gasifier can be substituted with another type of gasifier, a coke oven gas source, an export gas source, a blast furnace, or the like—collectively referred to herein as a syngas source. Depending on the chemical composition of the syngas, a two-stage CO recovery unit 18 or the like is preferred to achieve the desired 35-70% CO-rich stream delivery to the transition zone 32 of the DR furnace 28 . Optionally, the hydrocarbon-rich stream 36 , with or without adjustment of its moisture via the dehumidifier 38 and sulfur content via the desulfurizer 40 and preheating via the preheater 26 , is blended with the CO-rich stream 20 and/or delivered directly to the transition zone 32 and/or the cooling zone 34 of the DR furnace 28 . Specifically, all transition zone/cooling injection may be via ports disposed about the circumference of the transition zone 32 and/or cooling zone 34 of the DR furnace 28 . The key aspect is that it is partially or completely reduced iron oxide that is exposed to the CO-rich stream 20 and, optionally, the hydrocarbon-rich stream 36 .
[0051] Although the present invention is illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention, are contemplated thereby, and are intended to be covered by the following non-limiting claims.
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A method for producing direct reduced iron having increased carbon content, comprising: providing a carbon monoxide-rich gas stream; and delivering the carbon-monoxide-rich gas stream to a direct reduction furnace and exposing partially or completely reduced iron oxide to the carbon monoxide-rich gas stream to increase the carbon content of resulting direct reduced iron. The carbon monoxide-rich gas stream is delivered to one or more of a transition zone and a cooling zone of the direct reduction furnace. Optionally, providing the carbon monoxide-rich gas stream comprises initially providing one of a reformed gas stream from a reformer and a syngas stream from a syngas source. Optionally, the carbon monoxide-rich gas stream is derived, at least in part, from a carbon monoxide recovery unit that forms the carbon monoxide-rich gas stream and an effluent gas stream. Optionally, the method still further includes providing a hydrocarbon-rich gas stream to one or more of a transition zone and a cooling zone of the direct reduction furnace, with and/or separate from the carbon monoxide-rich gas stream.
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FIELD OF THE INVENTION
The present invention relates to a method of washing a blind widely used by attaching it to the window of an ordinary house, an office, a factory of the like for the purpose of preventing entrance of exterior light.
BACKGROUND OF THE INVENTION
Various types of dust or similar dirty material of which kind varies depending on the environment is likely to be adhesively deposited on louvers constituting the blind, and it is not easy to remove the dust from the louvers. With a small number of blinds, it is not impossible to wash each louver with an operator's hands using a map. At any rate, it is not easy to wash the louvers of the blind.
In view of the foregoing fact, there has been proposed the following blind washing method (refer to Japanese Patent Laid-Open NO. 64-5512).
Specifically, a method of washing a blind with plate-like light shading louvers arranged in parallel to each other with adjustable distance held between adjacent louvers, wherein
while the adjacent louvers are sufficiently parted away from each other, a rod-like insert projecting from the surface of a flexible belt base material is inserted between the adjacent louvers,
thereafter, the blinds are folded and the distance between the adjacent louvers is reduced while the rod-like insert is inserted into the folded blind, and
the folded blind is washed in a washing liquid.
An advantage of the prior art is that since the distance between the adjacent louvers is reduced to a necessary minimum extent, the height as measured in the vertical direction is reduced and then the blind is washed, a washing operation can be achieved with a comparatively small washing apparatus.
However, since means usable for reducing the distance between the vertically adjacent louvers to a necessary minimum extent is a rod-like insert projecting from the surface of a flexible belt-like base material, the foregoing means has the following problems.
That is, according to the prior method, while the blind is expanded in the vertical direction, the belt-like base material comes in contact with the blind, and the rod-like insert is inserted into the adjacent louvers. However, for the reason that the distance between the adjacent louvers of one blind can not always be adjusted to be constant at all times, there arises a problem in that all rod-like inserts are not always inserted between the vertically adjacent louvers when the belt-like base material comes in contact with the blind. Another problem is that in almost every case, when an operator checks the blind after completion of the aforementioned operation, he often finds that many rod-like inserts are incorrectly inserted between the adjacent louvers, and there arises a necessity of manually inserting the rod-like inserts between the incorrectly inserted adjacent louvers by hand. Thus, another problem is that when the conventional method is employed, each inserting operation is inefficiently performed and rod-like inserts are inconveniently used.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the aforementioned background.
An object of the present invention is to provide a method of washing a blind which assures that a distance between adjacent louvers of the blind can easily be reduced to a necessary minimum dimension and dirty material can easily and reliably be removed from the louvers with small washing means without an occurrence of the problem that at the time of washing, all rod-like inserts projecting from the belt-like base material usable for reducing the distance between the adjacent louvers of the blind can not always be inserted between the adjacent louvers merely by allowing the belt-like base material to come in contact with the blind, and thus, many rod-like inserts are unavoidably inserted between the adjacent louvers by hand.
According to the present invention, there is provided a method of washing a blind comprising the following steps to be successively executed of;
a spacer inserting step of inserting offset ring-like portions between the vertically adjacent louvers by squeezing a coil spring-like spacer member against the louvers of a blind to be washed at a right angle relative to the louvers of which distance is enlarged and which are held in the horizontal direction, the offset ring-like portion being located corresponding to each part of the coil spring-like spacer member (i.e., by a quantity of one pitch),
a louver distance reducing step of reducing the distance between the vertically adjacent louvers of the blind by holding the offset ring-like portions in the clamped state so as to allow the gap corresponding to the diameter of a wire forming the offset ring-like portions to be left as it is,
a washing step of washing the blind while the distance between the adjacent louvers is reduced, and
a drying step of drying the blind while the coil spring-like spacer member is disconnected from the washed blind.
The coil spring-like spacer member should not be limited to only an annular contour as seen in a plan view, and it may exhibit the contour of, e.g., a triangle, a rectangle, a pentagon or the like. Although the coil spring-like spacer member exhibit a polygon, it is preferable that each corner of the polygon is rounded. In addition, the coil spring-like spacer member may be such that a part of the substantially annular coil as seen in a plan view is inwardly bent and the bent part is formed to a substantially U-shaped recessed contour to surround the center of the annular coil. In this case, as described later, when the coil spring-like spacer member is set for washing the blind, the strings disposed for connecting the louvers of the blind to each other or changing an inclination angle of the blind are protected them from damage caused by a washing operation while they are inserted in the substantially U-shaped contour.
It is acceptable that the diameter of a wire forming the coil spring-like spacer member is set to 2 mm or more. In other words, it is acceptable that the diameter of the wire forming the coil spring-like spacer member is determined such that the constant distance between the adjacent louvers determined when a part of the offset ring-like portion equal to one pitch of the coil spring-like spacer member is inserted between the louvers becomes a minimum smallest limit distance for effectively performing a washing operation when washing the blind while it is dipped in a washing liquid or washing the blind while brushes are inserted into the gap between the adjacent louvers. To this end, the diameter of the wire is set to 2 mm or more.
A material for the coil spring-like spacer member can be selected from various kinds of materials, and in the case that the washing step is executed while the blind is dipped in the washing liquid and at this time supersonic vibration is utilized, it is convenient that the coil spring-like spacer member is molded of a plastic material or a similar non-metallic material. This is because in the case where the coil spring-like spacer member is molded of a plastic material or other non-metallic material, the surface or the coating layer of a part of the louver coming in contact with the coil spring-like spacer member is not injured when a washing operation is performed utilizing supersonic vibration.
In case of other washing means, e.g., in the case that a washing operation is performed with brushes inserted into the gaps between the louvers of the blind, it is not necessary that the material employable for the coil spring-like spacer is limited to a specific material.
It is suitable that the diameter of the offset ring-like portion associated with the coil spring-like spacer member is dimensioned to a size corresponding to the width of the louver, i.e., within the range from slightly short of the width of the louver to slightly long of the same.
To execute the washing step, washing means suitable for washing the blind while the distance between the adjacent louvers is assumed as a minimum limit can freely be employed. For example, as mentioned above, the means for performing a washing operation while the blind is dipped in the washing liquid can be employed, and moreover, the means for performing a washing operation while brushes are inserted into the gaps between the adjacent louvers can be employed.
For example, in the case that a washing operation is performed while the blind is dipped in the washing liquid, it is suitable that the washing liquid is displaced during the washing operation, and the displacement of the washing liquid can be achieved, e.g., by stirring the washing liquid with the aid of stirring means or by blowing air in the washing liquid. In this case, to increase a washing effect, it is suitable that supersonic vibration is transmitted to the blind via the washing liquid, and it is suitable that a frequency of the supersonic vibration is set to, e.g., 47 kHz. It is obvious that the frequency of the supersonic vibration should not be limited to the above-noted one, and other suitable frequencies belonging to the range of the supersonic vibration can be selected. It is sufficient that such high frequency vibration is applied to the washing liquid for a short time of one to two minutes.
Since the present invention is constructed in the above-described manner, a washing operation can be performed for the blind in the following manner.
First, the spacer inserting step is executed.
For example, the blind is expanded while it is engaged with a window, and the distance between the adjacent louvers is expanded to a maximum extent. A part of the offset ring-like portions corresponding to the coil spring-like spacer member is inserted between the vertically adjacent louvers by squeezing, e.g., two coil spring-like spacer members against the blinds of which distance is enlarged in the above-described manner.
In the case that a part of a substantially annular coil as seen in a plan view is inwardly bent and the bent part exhibits a substantially U-shaped recessed contour while surrounding the center of the annular coil therein, when the coil spring-like spacer member is set to the blinds, the strings disposed to connect the respective louvers to each other or changing the inclination angle of the louvers are positioned at certain positions and they are set such that they are involved in the substantially U-shaped recessed part.
In the case that the coil spring-like spacer member is suspended while its upper end is supported, the coil spring-like spacer member has a length such that the upper end of the coil spring-like spacer member substantially corresponds to the upper end of the blind to be washed and its lower end substantially corresponds to the lower end of the blind. The number of offset ring-like portions is larger than the number of the gap of the louvers, and each of the offset ring-like portions corresponds to the position of 1/4 as measured from the both the sides of lateral width of the blind. In the case that the coil spring-like spacer member includes a bent portion which is constructed such that the center of the coil spring-like spacer member is involved in the substantially U-shaped recessed contour at a part of the substantially annular coil as seen in a plan view, the coil spring-like spacer member corresponds to a certain position of the strings disposed for connecting the respective louvers of the blind to each other or changing the inclination angle of the blind.
Then, when the coil spring-like spacer member is squeezed against the blind side from, e.g., the upper end side, the corresponding part of the offset ring-like portions of the coil spring-like spacer member is squeezed or positioned between the vertically adjacent louvers of the blind so that it is inserted therebetween.
This is described in more detail. When the coil spring-like spacer member coming in contact with the front surface of the blind is slightly squeezed toward the blind side by sliding an operator's hand along the coil spring-like spacer while the upper end of the blind is supported and suspended, the corresponding offset ring-like portions can easily be inserted between the vertically adjacent louvers in a single operation. Even though the vertically adjacent louvers and the corresponding offset ring-like member are located at the vertically non-coincident position, since the coil spring-like spacer member is spirally extended, they are displaced to the vertically coincident position as an operator's hand slides along the coil spring-like spacer member in that way, whereby the offset ring-like portions are inserted between the corresponding louvers.
This operation can very simply and speedily be achieved without any necessity of adjusting the distance between the adjacent louvers.
Thereafter, the louver distance reducing step is executed.
The blind expanded to a maximum extent is raised up so that the distance of the vertically adjacent louvers is reduced to a dimension corresponding to the diameter of the wire of the coil spring-like spacer member.
When the blind is raised up to reduce the distance between the louvers, since the offset ring-like portions of the coil spring-like spacer member are inserted between the vertically adjacent louvers, the vertically adjacent louvers hold the offset ring-like portions in the clamped state, the reduction of the distance between the louvers is stopped, and the distance of the louvers is adjusted and held to an adequate smallest limit.
Next, the washing step is executed.
To execute the washing step, besides the means for performing a washing operation by dipping the blind in the washing liquid, various means such as means for performing a washing operation by inserting brushes between the adjacent louvers of the blind can be employed.
In the case that a washing operation is performed by dipping the blind in the washing liquid, the washing operation is performed in the following manner.
A washing liquid prepared, e.g., by dissolving a neutral detergent or an alkaline detergent in water is put in a washing bath. The washing liquid is heated to, e.g., 40° C. or more, the washing liquid is displaced by actuating suitable means, the blind including the louvers of which distance is adjusted to a minimum extent is suspended in the washing bath or the blind is placed on a frame-like table put in the washing liquid so that the blind is dipped in the washing liquid to wash the blind.
In addition, supersonic vibration generating means is placed in the washing bath, and supersonic vibration is transmitted to the blind via the washing liquid so that dirty material adhesively deposited on the louver can be floated up by cavities caused by the supersonic vibration. It is acceptable that the frequency of the supersonic vibration is set to 47 kHz and the supersonic vibration is applied to the blind for a time of 1 to 2 minutes. Since the dirty material floated up by the action of the cavities caused by supersonic vibration is parted away from the surface of the louver by the displacement of the washing liquid, an excellent washing effect is obtainable.
Thereafter, the blind is rinsed by, e.g., dipping it in flowing water or it is dipped in water having a special rinsing agent or a water separating agent for rinsing the blind.
In the case that a washing operation is performed by inserting brushes into the adjacent louvers, a washing operation can be performed in the following manner.
The blind is placed on a suitable holder such as an idling roller and an adequately diluted washing liquid adhere to the blind. A brush reciprocating in the longitudinal direction of the louver or a rotating brush is inserted into the gap of the louvers in one direction or in both directions so that the dirty material is removed from the louver by the physical function of the brush and the chemical function and the physical function caused by the washing liquid. This washing operation is performed from one end of the blind and to the other end of the same. After completion of the washing operation, the washing liquid is flown away by feeding water or feeding water added with a rinsing agent or a water separating agent, whereby the washing operation is completed.
Thereafter, a drying step is executed for the washed blind.
The drying step is practiced such that the upper end of the blind is engaged with engagement means located at a high position, the blind is expanded to enlarge the distance between the adjacent louvers, and the coil spring-like spacer member is disconnected from the blind. For example, the blind is forcibly dried by blowing hot air to the blind or it is naturally dried by leaving the blind in the room or outside of the room as it is. In some cases, it is sufficient that the blind is dried merely by leaving the blind as it is without any particular action executed.
Other objects, features and advantages of the present invention will become apparent from reading the following description which has been made in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is schematic front view which shows a coil-like spacer engaged with an expanded blind with louvers held in the horizontal state.
FIG. 2 is a illustrative perspective view of the blind which shows offset ring-like portions inserted between adjacent louvers of the blind.
FIG. 3 is an illustrative side view of the blind which shows the state directly before the offset ring-like portions of the coil-like spacers are inserted between the adjacent louvers of the blind.
FIG. 4 is an illustrative side view of the blind which shows the state in which offset ring-like portions of the coil-like spacer are inserted between the adjacent louvers of the blind.
FIG. 5 is a fragmentary enlarged side view of the blind which shows the offset ring-like portions of the coil-like spacer inserted between the adjacent louvers while the blind is contracted.
FIG. 6 is an illustrative front view of the blind which shows the offset ring-like portions of the coil-like spacer inserted between the adjacent louvers of the blind while the blind is contracted.
FIG. 7 is an illustrative side view of the blind which shows the offset ring-like portions of the coil-like spacer inserted between the adjacent louvers of the blind while the blind is contracted.
FIG. 8 is an illustrative side view which shows two blinds each having the offset ring-like portions of the coil-like spacer inserted between the adjacent louvers of the blinds while the blind is contracted and disposed in a washing bath.
FIG. 9 is an illustrative front view which shows the washed blind prior to being placed in a rinsing bath.
FIG. 10 is a schematic illustrative front view which shows the blind expanded with the coil spring-like spacer removed therefrom upon completion of a washing operation.
FIG. 11 is a schematic perspective view of the coil spring-like spacer.
FIG. 12 is a flowchart which shows the steps to be executed in accordance with a first embodiment of the present invention.
FIG. 13 is a schematic view which shows the state in which the blind is washed by reciprocable brushes and a rotary brush.
FIG. 14 is a partially cut illustrative front view which shows the state in which a reciprocable brush is received between the adjacent louvers of the blind.
FIG. 15 is a partially cut illustrative side view which shows the state in which a rotary brush is received between the louvers of the rotary brush.
FIG. 16 is a partially cut illustrative plan view which shows by way of other example the state in which a coil spring-like spacer is set between the adjacent louvers of the blind.
FIG. 17 is a schematic perspective view which shows by way of another example the structure of a coil spring-like spacer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in detail hereinafter with reference to the accompanying drawings.
FIG. 1 to FIG. 12 show a first embodiment of the present invention, respectively.
First, main components and devices, i.e., coil spring-like spacer 2, a washing bath 2 and a rinsing bath 3 will be described below.
As shown in FIG. 11, the coil spring-like spacer 1 is a coil-like member, and it is assumed that a coil spring-like spacer 1, dimensioned to a size of a blind B to be washed, is prepared. The coil spring-like spacer 1 exhibits an annular contour as seen in a plan view, and has a diameter of about 70 mm and a wire constituting the coil spring-like spacer 1 has a diameter of 2 mm. The coil spring-like spacer 1 is molded of an elastic plastic material.
As shown in FIG. 8, a washing bath 2 is constituted of a box-shaped bath main body 2a, a plurality of supersonic vibration generators 2b arranged on the bottom of the bath main body 2a, a recirculating pump 2c disposed such that a washing liquid is sucked from the lower part of the bath main body 2a and is discharged from the upper part of the bath main body on the opposite side, and panel heaters 2d attached to the inner surfaces of the side walls of the bath main body 2a.
The supersonic vibration generators 2b are adapted to generate a supersonic vibration of 47 kHz are employed for executing the first embodiment of the present invention.
The panel heaters 2d are intended to heat a washing liquid 5 filled in the bath main body 2a to an adequate temperature and each panel heater 2d includes a temperature sensor and a controller for controlling a quantity of electricity to be supplied to the panel heater 2d in response to an output signal from the temperature sensor. The temperature sensor and the controller are not shown in the drawings. The temperature of the bath main body 2a can freely be set, and according to the first embodiment of the present invention, it is acceptable that the temperature is set to 40° C.
As to the washing liquid 5, which is provided in the bath main body 2a, it is sufficient that an adequate kind of detergent selected corresponding to the nature of the dirty material deposited on the blind B to be washed is added to water. In the first embodiment of the present invention, the washing liquid 5 is intended to wash the blind B used in an ordinary office, and since the content of the dirty material generally comprises dust, tar of tobacco or the like, it is acceptable that an alkali based detergent is added to water to prepare a washing liquid.
Two pair of stands 4 are vertically displaceably arranged in the bath main body 2a, and holding arms 4a laterally extending from the intermediate position of each stand 4 serve to hold the blind B thereon for washing the blind B.
As shown in FIG. 9, a rinsing bath 3 is a box-like bath for receiving a rinsing liquid 6 therein, and it is acceptable that dimensions and a capacity of the rinsing bath 3 are determined such that the blind B can be dipped in the rinsing bath 3. It is sufficient that the rinsing liquid 3 is merely water but rinsing liquid having a rinsing agent and a water separating liquid added to water may be employed for executing this operation.
According to the first embodiment of the present invention, the blind B is washed using the above-described components and devices in conformance with steps shown in FIG. 12.
As shown in a step S1, first, a step of inserting a spacer is executed.
As shown in FIG. 1, the blind B is expanded to such a maximum extent that the window is covered with the blind B in conformance with a manner of usage thereof, the distance between adjacent louvers is enlarged to a maximum extent, while the louvers are held into a horizontal state, two coil spring-like spacers 1 are positioned against the blind B with a vertical attitude so that offset ring-like portions 1a of the coil spring-like spacer 1 are inserted between adjacent louvers L of the blind B located one above another.
The two coil spring-like spacers 1 are located at the positions away from the opposite ends of the blind B by a distance of one quarter of the width of the blind B.
The above-described operation will be explained in more detail. As shown in FIG. 3, when the coil spring-like spacer 1 is brought in contact with the adjacent louvers L of which distance is enlarged and the coil spring like-spacer 1 is squeezed toward the louver L side in the A arrow-marked direction, respective offset ring-like portions 1a of the coil spring-like spacer 1 are inserted between the vertically adjacent louvers L as shown in FIG. 2 and FIG. 4.
The squeezing operation of the coil spring-like spacer 1 in the A arrow-marked direction can simply be performed by squeezing the coil spring-like spacer 1 in the A arrow-marked direction while sliding an operator's hand from the above to the below. Even though the respective offset ring-like portions 1a are slightly deviated from the distance between the blinds B, since the coil spring-like spacer 1 itself is constructed in the form of a spiral contour and has resiliency, the foregoing deviation disappears merely by thrusting the coil spring-like spacer 1 in the A arrow-marked direction while sliding an operator's hand along the coil spring-like spacer 1 from above to below, whereby the offset ring-like portions 1a are inserted between the louvers L.
Thereafter, a step of reducing the distance between the louvers as represented by a step S2 in FIG. 12 is executed.
As mentioned above, the blinds B expanded to a maximum extent are raised up to reduce the distance between the louvers B in conformance with a manner of usage thereof. Since the offset ring-like portions 1a of the coil spring-like spacer 1 are inserted between the vertically adjacent louvers L as shown in FIG. 2, the distance between the louvers is reduced to a dimension of 2 mm corresponding to a diameter of the wire constituting the offset ring-like portion. FIG. 5 shows this state.
Next, a step of washing is executed.
First, as represented by the step S3 in FIG. 12, the blind B is put in the bath main body 2a of the washing bath 2 so that it is washed therein.
The washing liquid 5 is preliminarily put in the bath main body 2a of the washing bath 2, and the heaters 2d are activated to hold the washing liquid 5 at a temperature of 40° C. While the foregoing state is maintained, the blinds B are held on the arms 4a of the pair of stands 4 as shown in FIG. 8 and are dipped in the bath main body 2a of the washing bath 2 so as to allow the washing bath 2 to perform a washing operation.
In this case, the recirculating pump 2c is operated to recirculate the detergent solution in the bath main body 2a, and the supersonic generators 2b are activated to generate supersonic vibration.
The supersonic vibration generated by the supersonic vibration generators 2b is transmitted to the respective louvers of the blind B so that various dirty material adhesively deposited on the louvers L of the blind is floated up by the action of cavities generated by the supersonic vibration.
On the other hand, flow is caused with the washing liquid 5 in the bath main body 2a by the function of the recirculating pump 2c so that the dirty material floated from the surfaces of the respective louvers L is washed away from the surfaces of the louvers L, resulting in a washing effect being attained.
It is obvious that the aforementioned action is excellently achieved by opening the gap of about 2 mm between the vertically adjacent louvers L in the presence of coil spring-like spacers 1, and the foregoing gap is closed to the minimum limit which assures that the blind B is washed while it is compactly folded.
According to the first embodiment of the present invention, the supersonic generators 2b and the recirculating pump 2c are driven for two minutes whereby the respective louvers L of the blind B are sufficiently washed.
The position where the offset ring-like portions 1a of the coil spring-shape spacer 1 come in contact with the louvers L exhibits an excellent washing effect probably due to relative fine displacement caused by the supersonic vibration.
After completion of the washing treatment for two minutes, as represented by step S4 in FIG. 12, the blind B is placed in the rinsing bath 3 to rinse the blind B. As shown in FIG. 9, the rinsing treatment is achieved by dipping the blind B once in the rinsing liquid 6, slightly displacing it and then pulling it up.
After completion of the rinsing step, a drying step is executed. First, as represented by step S5, the upper end of the rinsed blind B is engaged with engagement means located at an elevated position, and it is expanded as shown in FIG. 10 in conformance with a manner of usage thereof so that the coil spring-like spacer 1 is disconnected from the blind B.
Next, as represented by step S6 in FIG. 12, the blind B is expanded and then dried while it is left immovable. The state of extension of the blind B is shown as in FIG. 10. In the first embodiment of the present invention, since a rinsing liquid having a rinsing agent and a water separating agent added thereto is employed for the blind B, water is easily separated from the blind B so that the blind B can speedily be dried.
Next, a second embodiment of the present invention will be described. FIG. 13 to FIG. 17 show the second embodiment of the present invention, respectively.
First, main components and devices to be used for a method of washing a blind in accordance with the second embodiment of the present invention, i.e., a coil spring-like spacer 11, a reciprocable brush 12 and a rotary brush 13 will be described.
As shown in FIG. 13, the reciprocable brush 12 is arranged in the proximity of the intermediate position between fore and rear idling rollers 14 each serving as a blind receiving portion so that it can be raised and lowered, and moreover, displaced in the forward/rearward direction (in the leftward/rightward direction in FIG. 13) by a driving portion 12b belonging to the reciprocable brush 12.
The rotary brush 13 is arranged below the reciprocable brush 12 so that it can be raised and lowered, and moreover, rotated by a driving portion 13b belonging to the rotary brush 13.
A water ejecting nozzle 15 and a water liquid ejecting nozzle 16 are arranged in front of the reciprocable brush 12, i.e., on the right side of the same, and a water ejecting nozzle 17 is arranged rearward of the reciprocable brush 13, i.e., on the left side of the same.
As shown in FIG. 16 and FIG. 17, the coil spring-like spacer 11 includes a plurality of U-shaped string protecting portions 11b, and a part of offset ring-like portion 11a is bent inwardy to constitute a U-shaped string protecting portion which surrounds the central portion of each offset ring-like portion. As shown in FIG. 17, the U-shaped string protecting portions 11b are formed at the same positions of the offset ring-like portions 11a.
The coil spring-like spacer 11 is dimensioned to have a diameter of about 70 mm, and the diameter of a wire constituting the coil spring-like spacer 11 is dimensioned to 2.5 mm. The coil spring-like spacer 11 is molded of an elastic plastic material.
According to this embodiment, the blind B is washed in the following manner using the foregoing components and devices.
In the same manner as the first embodiment, first, the blind B is expanded to a maximum extent to open the distance between the louvers L to a maximum extent. While the coil spring-like spacers 11 are held in the horizontal state, the coil spring-like spacers 11 are squeezed against the blind B with a vertical attitude so that the offset ring-like portions 11a are inserted between the vertically adjacent louvers L of the blind B. At this time, the coil spring-like spacer 11 is located at the position where strings H are present for connecting the louvers L of the blind B to each other or changing the inclination angle of the louvers B, and the opening portion side of the U-shaped string protecting portions 11b is oriented to the strings H, and thereafter, the coil spring-like spacer 11 is thrust against the louvers L of the blind B. As shown in FIG. 16, while the strings H are inserted in the U-shaped string protecting portion 11b, the offset ring-like portion 11a is inserted between the vertically adjacent louvers L.
Thereafter, a step of reducing the distance between the louvers is executed.
The blind B expended to a maximum extent as mentioned above is pulled up and then reduced in conformance with a manner of usage thereof. As described above with reference to the first embodiment of the present invention, the distance between the louvers L is reduced to 2.5 mm because the distance is restricted by the offset ring-like portions 11a inserted between the vertically adjacent louvers L and it is reduced to a dimension corresponding to the wire constituting the coil spring-like spacer 11. In this case, since the diameter of the wire is 2.5 mm, the distance between the louvers L is reduced to 2.5 mm.
Next, a step of washing is executed.
While the blind B is placed on the idling rollers 14 such that the gap between the louvers L is oriented to be opened in the vertical direction, the blind B is displaced in the leftward direction from the right as shown in FIG. 13. At this time, the blind B is get wetted with the water ejected from the water ejecting nozzle 15 from the foremost end of the blind B, and subsequently, as the washing liquid is ejected from the washing liquid ejecting nozzle 16, the washing liquid adheres from the foremost end of the blind B wetted with the ejected water. Then, the blind B proceeds between the rotary brush 13 and the reciprocable brush 12 while the washing liquid assumes an adequate density of detergent.
In such manner, the blind B proceeds between the reciprocable brush 12 and the rotary brush 13 from the foremost end thereof having an adequate density of washing liquid adhered thereto, and thereafter, the reciprocable brush 12 is lowered to a necessary position, and the rotary brush 13 is raised up to a necessary position so that the reciprocable brush 12 performs reciprocable movement and the rotary brush 13 performs rotary movement.
As shown in FIG. 14, a brush portion 12a of the reciprocable brush 12 enters between the louvers L at the foremost end of the blind B from the above and performs reciprocable movement in the longitudinal direction of the blind B, and as shown in FIG. 13, a brush portion 13a of the rotary brush 13 enters between the louvers L from the below to perform rotary movement whereby the surfaces of the respective louvers are washed.
Thus, the dirty material deposited on the surfaces L of the blind B is removed therefrom by the physical force imparted to the brush portion 12a of the reciprocable brush 12 and the brush portion 13a of the rotary brush 13, and moreover, the dirty material is removed from the foregoing surface by the chemical or physical washing power corresponding to the property of the washing liquid.
As the blind B gradually proceeds corresponding to the speed of washing achieved by the reciprocable brush 12, the rotary brush 13 and the washing liquid, a washing operation can be performed from the foremost end of the blind B to the intermediate part of the same and then the intermediate part to the rearmost end of the blind B.
When the foremost end of the blind B passing between the reciprocable brush 12 and the rotary brush 13 proceeds further, as shown in FIG. 13, it is placed on the idling roller 14 located ahead of the foremost end of the blind B and smoothly moves so that a rinsing operation is performed by the water ejected from the water ejecting nozzle 17 located behind the reciprocable brush 12 to remove the washing liquid and the dirty material involved in the latter.
When the whole blind B passes past the reciprocable brush 12 and the rotary brush 13, and moreover, passes below the water ejecting nozzle 17, a washing operation for the blind B is completed.
When a certain position of the strings H disposed for connecting the respective louvers L or changing the inclination angle of the louvers L of the blind B passes between the reciprocable brush 12 and the rotary brush 13, the strings H are protected by the coil spring-like spacer 11. In some case, the reciprocable brush 12 may be raised and lowered at the foregoing position. In this case, only this part is manually washed later.
In the case that the washing liquid is insufficiently rinsed with the aforementioned extent, when only ejection of the washing liquid from the washing liquid ejecting nozzle 16 is interrupted and the same washing step is once more repeated, the rinsing operation becomes perfect.
After completion of the washing step, a drying step is executed.
First, the upper end of the washed blind B is engaged with engagement means located at a high position, the distance between the adjacent louvers is enlarged by expanding the blind B in conformance with a manner of usage, and the coil spring-like spacer 11 is disconnected from the blind B. The blind B held in the foregoing state is left immovable so that it is naturally dried.
As will be understood from the description on the first embodiment and the second embodiment of the present invention, since the distance between the respective louvers of the blind can be reduced to a necessary minimum extent using the coil spring-like spacer member, an advantageous effect is that a washing operation can be performed by small-sized washing means.
Insertion of the coil spring-like spacer member into the respective louvers is very easy, and the coil spring-like spacer member can easily and speedily be inserted between the respective louvers merely by squeezing the coil spring-like spacer member against the respective louvers in the aforementioned manner especially without any necessity for adjusting the positional relationship between the offset ring-like portion of the coil spring-like spacer member and the louvers.
In the case where the coil spring-like spacer member is constituted of a non-metallic material, there does not arise a problem that a coating at the contact portion with the louvers is injured also when supersonic vibration is utilized for the washing step.
In the case where the diameter of the offset ring-like portion of the coil spring-like spacer member is dimensioned corresponding to the width of the louver, since the coil spring like-spacer member is inserted between the vertically adjacent louvers from the foremost end to the rearmost end thereof, the gap exactly corresponding to the diameter of the wire can be kept between the louvers.
In addition, in the case that the U-shaped string protecting portion recessed in the substantially U-shaped contour is formed by inwardly bending a part of all the offset ring-like portion of the coil spring-like spacer member corresponding to each other while surrounding the center of the offset ring-like portion, since the strings disposed for connecting the louvers of the blind or changing the inclination angle of the louvers can be protected by the foregoing structure, it is convenient in the case that a washing operation is performed using brushes.
While the present invention has been described above with respect to the preferred embodiments thereof, it should be noted that the present invention should not be limited only to these embodiments but various changes or modifications may be made without departure from the scope of the present invention as defined by the appended claims.
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A method of washing a blind which assures that a gap between adjacent louvers of the blind can easily be reduced to a shortest distance and dirty material can reliably be removed from the louvers. The method is practiced such that while the distance between the adjacent louvers is widened, a coil spring-like spacer is pressed against the blind. Offset ring-like portions of the spacer are inserted between the vertically adjacent louvers, and thereafter, the distance between the louvers is reduced to the diameter of a wire material forming the spacer while holding the offset ring-like portions in a clamped state. Subsequently, while the foregoing state is maintained, the blind is washed in a washing liquid circulated by a recirculating pump. Supersonic vibrations, generated by a supersonic vibration generator, are applied to the washing liquid. Then the blind is rinsed in a rinsing bath, and finally, after the coil spring-like spacer is disconnected from the blind, the blind is dried.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is a National Phase filing under 35 U.S.C. §371 of PCT/ib2010/050049 filed on Jan. 7, 2010; and this application claims priority to Application No. 0900077 filed in France on Jan. 9, 2009 under 35 U.S.C. §119; the entire contents of all are hereby incorporated by reference.
BACKGROUND
The present invention relates to improvements made to the cooling sections of lines for the continuous processing of metal strip, in particular annealed, galvanized or tin strip.
A line for the continuous processing of metal strip consists of a succession of thermal processing stations, in particular sections for heating, maintaining temperature, cooling, ageing etc.
The present invention relates to the cooling sections of continuous processing lines and more particularly sections for rapid cooling with the spraying of a liquid onto the strip.
The cooling liquid is generally water, which may be treated in advance, for example so as to extract the dissolved oxygen or the mineral salts therefrom, and which may contain additives for improving the thermal exchange or limiting the oxidation of the strip.
Cooling using water makes it possible to obtain very high cooling slopes, higher than those which may be obtained with gaseous cooling.
The cooling of the strip can also be obtained by spraying the strip with a mixture consisting of a gas and a liquid. In this case, the gas is generally present as a carrier gas for effecting the atomization and the spraying of the liquid onto the strip. The gas used is usually nitrogen but can also consist of a mixture of nitrogen and hydrogen, or any other gas.
The liquid may be sprayed in the form of a mist or atomized with larger-sized droplets or in the form of a continuous liquid.
In the thermal cycle that is effected, the cooling of the strip can then begin when the strip is at a high temperature, for example 750° C. When the strip is at a temperature that is much higher than the boiling temperature of the cooling liquid, a film boiling or vapor film situation occurs. This phenomenon is called calefaction. The layer of vapor causes something of a barrier to the transfer of heat between the strip and the water, thus reducing the effectiveness of the cooling with water.
For the example of water, the boiling temperature is close to 100° C. It can vary by a few degrees depending on the composition of the water and the quantity of additives in it.
In sum, in the situation of a vapor film (film boiling), the problem can be reduced to cooling an imaginary wall to 100° C. using water. The temperature of the atomized water is then a first-order parameter for controlling the intensity of the cooling, □=h (100° C.−T water ° C.).
In terms of the calefaction phenomenon, there is a critical temperature for the strip, known as the “Lindenfrost temperature”. For a temperature above this critical temperature, the cooling takes place with a vapor film and hence the cooling is ineffective but relatively very homogeneous. For a lower value of the temperature close to the critical temperature, the effectiveness of the cooling is significantly better but rather chaotic. In this case, there is a localized disappearance of the layer of vapor (the term “redampening” is then used), with a very high increase in the heat transfer. A steep temperature gradient results over the width of the strip, which can give rise to plastic deformations of the strip, for example the appearance of folds, or to heterogeneous mechanical properties over the width of the strip.
This critical temperature is dependent on numerous parameters, including the characteristics of the atomization, the temperature of the atomized liquid or the nature and temperature of the cooled surface.
The main factor is the effect on this temperature of the temperature of the cooling liquid and of the atomization parameters, ie the velocity and diameter of the droplets.
The object of the invention is especially to effect a homogeneous cooling of the metal strip, in particular to prevent the formation of folds or substantial differences in mechanical characteristics over the width and/or length.
SUMMARY OF THE INVENTION
According to the invention, a method for controlling the cooling of a moving metal strip in a cooling section of a continuous processing line which sprays onto the strip a liquid or a mixture consisting of a gas and a liquid, the cooling being dependent on parameters including the temperature, velocity and characteristics of the stream of cooling fluid, is characterized in that:
one or more zones are determined in which the parameters of the cooling are such that the localized disappearance of a vapor film could or does occur at the surface of the hot strip, causing a redampening of the strip, and, as a cooling parameter in the zone or zones so determined, at least the temperature of the cooling liquid is adjusted, which temperature is increased in the zone where a redampening could occur, or where it does occur, so as to maintain or restore cooling with a vapor film at the surface of the strip, resulting from the calefaction phenomenon of the cooling liquid in contact with the hot strip.
The invention is thus primarily a method for controlling the cooling of a moving metal strip in a continuous processing line which sprays onto the strip a liquid or a mixture consisting of a gas and a liquid, so as to maintain cooling “with a vapor film” at the surface of the strip, resulting from the calefaction phenomenon of the cooling liquid in contact with a hot strip, consisting in increasing the temperature of the cooling liquid in the zone where a redampening could occur, or where it does occur, resulting from the localized disappearance of the vapor film, so as to preserve or restore cooling with a vapor film at the surface of the strip.
Advantageously, another adjusted cooling parameter consists in an atomization parameter formed by the velocity and/or the diameter of the droplets of cooling liquid in the relevant zone or zones.
When the cooling method employs a cooling section having a plurality of successive cooling units arranged in the direction in which the strip moves, the temperature of the cooling liquid can be adjusted such that it differs between two successive cooling units of the cooling section.
Combined adjustment of the temperature and the flow rate of the cooling liquid can be carried out so as to enable the heat flow extracted from the strip to be modulated.
The temperature of the cooling liquid can be adjusted over the width of the strip. Multiple units for spraying the cooling fluid can be distributed over the width of the strip, and the temperature and flow rate of the cooling liquid for each spraying unit are adjusted over the width of the strip.
The temperature of the liquid can be adjusted at the beginning of the cooling so as to limit the variation in the temperature slope resulting from cooling, compared with heating or compared with maintaining the preceding temperature.
The temperature of the liquid can be adjusted according to the target cooling capacity so as to limit the variations in the flow rate of the cooling liquid.
Advantageously, in order to determine one or more zones in the cooling section in which the parameters of the cooling are such that localized disappearance of a vapor film could occur, or does occur, at the surface of the hot strip, causing a redampening of the strip, during prior tests,
the operating conditions are varied, it is observed when the redampening of the strip occurs and in which cooling section, and, all other operating conditions being unaltered, the temperature of the liquid is gradually raised in the zone where the redampening occurs so as to be able to define the liquid temperature required to eliminate the redampening and restore a situation where there is a vapor film in the zone under study.
The tests can be repeated in a following zone, in the direction in which the strip moves, so as to preserve a vapor film throughout the cooling section or, when that is not possible, to defer the beginning of the redampening to a lower temperature.
Advantageously, in order to define the point in time at which the redampening occurs and the zone in which it occurs, the appearance of a steep increase in the transverse temperature gradient of the strip, and of a significant discontinuity in the cooling slope resulting from the more intense cooling with no film vapor present, is determined with the aid of devices for measuring the temperature of the strip in the zones where the redampening is likely to occur.
The tests are preferably carried out in a zone situated along the edge of the metal strip where the temperature of the strip is between 450° C. and 250° C., and at several points over the width of the strip so as to detect large variations in temperature.
The invention also relates to a cooling section of a continuous processing line for implementing the above-defined method, which section has units for spraying a metal strip with a liquid or a mixture consisting of a gas and a liquid, and is characterized in that it has, for at least one unit for spraying cooling liquid onto the strip, a system for supplying cooling liquid which comprises two separate circuits for supplying cold water and hot water, each being equipped with a regulating valve and connected to a same outlet duct, a controller for the flow rate of the mixture being provided on the outlet duct, as well as a controller for the temperature of the mixture.
The supply system can have a regulator which makes it possible to adjust the proportion of the flow rates of cold water and hot water so as to obtain the overall target flow rate of the liquid at the desired temperature, and this is the case for each spraying device.
According to the invention, the temperature of the cooling liquid can be regulated as a function of the desired thermal flow and as a function of the temperature of the strip.
Thus, just after the beginning of the cooling with, for example, a strip temperature of 700° C., cold water which may even be close to 0° C. is sprayed but when the strip reaches lower temperatures, for example 450° C., the water must be hotter so as to maintain the vapor film situation (film boiling).
With hotter water at the end of the cooling (for example 35° C. at the beginning of the cooling and 80° C. at the end of the cooling), the invention makes it possible to maintain control of the cooling while preserving a vapor film for longer. This controlling of the temperature of the water, which may be combined with an adjustment of the flow rate of water over the width of the strip, makes it possible to obtain a homogeneous strip temperature over its width.
Determination by calculating the Lindenfrost temperature is very difficult as many parameters affect the latter. The atomization parameters are very important. Thus, the size of the droplets, the distance between the droplets, the velocity of the droplets, the atomization temperature of the liquid, the proportion and the temperature of the atomizing gas affect the Lindenfrost temperature. It is also affected by the temperature, surface roughness and emissivity of the strip. The flow of heat exchanged by the strip is also a decisive factor. In fact, the Lindenfrost temperature depends on the speed with which the droplet of liquid reaches its vaporization temperature. The quicker this happens, the lower the Lindenfrost temperature.
Owing to the complexity of the phenomenon, determining the critical temperature, or Lindenfrost temperature, is mainly a matter of experimentation, ideally directly on the plant when it is installed.
In the tests, different means are possible for defining the point in time at which the redampening occurs and the zone in which it occurs.
The appearance of the redampening leads to a sharp increase in the transverse temperature gradient of the strip and to a significant discontinuity in the cooling slope resulting from the more intense cooling with no vapor film present. The most simple method consists in placing devices for measuring the temperature of the strip in the zones where the redampening is likely to occur, for example along the edge where the temperature of the strip is between 450° C. and 250° C. and at several points over the width of the strip so as to detect these large variations in temperature.
Tables can be drawn up from these tests, stating, for each type of production on the line, the temperature of the cooling liquid required in each zone to prevent or delay the redampening of the strip.
These tables are then integrated into the control and command system of the plant so as to automatically take into account for each zone the appropriate reference temperature of the cooling liquid for the type of production on the line.
As explained above, the large number of parameters which affect the redampening of the strip means that such redampening occurs during normal production of the line in an unexpected zone. According to the invention, the temperature of the cooling liquid is increased by the operator in the zone in question, so as to defer the redampening until the following zone. Depending on the zone where this redampening occurs, the operator can in advance also increase the temperature of the cooling water in the following zone or zones in order to further defer the beginning of the redampening. The rise in the temperature to be applied will have been defined beforehand during the installation tests, for example by 5° C. It can also be adjusted by the operator.
The increase in the temperature of the cooling liquid in a zone may be accompanied by another adjustment of the atomization parameters so as to maintain the target temperature slope on the strip without reducing the speed of the line. For example, the flow rate of the cooling water can be increased in this zone. The increase in the flow rate of the water can be effected automatically by the control and command system of the line so as to reach the reference temperature of the strip when it exits the cooling zone. Again, the optimum settings will have been defined when the line is installed or by trial and error during operation.
The above description of the invention corresponds to the adjustment of the temperature of the cooling liquid so as to preserve the vapor film mode. Another means for obtaining this result, at a constant liquid temperature, consists in modifying the size of the droplets and the velocity at which they strike the strip.
In the case where the cooling liquid is atomized with a gas, the velocity and the diameter of the droplets will be adjusted by modifying the proportion of the gas.
In the case where the liquid is atomized without gas, the velocity and the diameter of the droplets will be adjusted by mechanically modifying the nozzle at the orifice for atomizing the liquid.
The same mode of operation as described above for optimizing the temperature of the cooling liquid is used to determine the atomization parameters experimentally using tests.
It will easily be understood that it is possible to combine a variation of the temperature of the cooling liquid and of the atomization parameters so as to preserve the vapor film mode.
According to the method of the invention, the temperature of the cooling liquid and the atomization parameters, ie the velocity and diameter of the droplets, can be adjusted in the zone where a redampening could occur or does occur, resulting from the localized disappearance of the vapor film so as to preserve or restore cooling with a vapor film at the surface of the strip.
On plants for cooling using the spraying of water, the main parameter for controlling the cooling is generally the density of the flow rate of water, expressed in kg/m 2 /s. When a gas is used as the spraying medium, it is not essential to regulate the flow rate of gas. According to the spraying device, the flow rate of gas naturally matches the flow rate of water. According to another example, the flow rate of gas remains constant.
BRIEF DESCRIPTION OF THE DRAWINGS
Apart from the arrangements explained above, the invention consists of a certain number of other arrangements which will be dealt with more explicitly below with the aid of exemplary embodiments described with reference to the attached drawings, which imply no limitation, in which:
FIG. 1 is a diagram of a configuration according to the invention for supplying a unit for spraying cooling liquid,
FIG. 2 is a perspective diagram in elevation of a cooling section according to the invention,
FIG. 3 is a diagram, similar to FIG. 2 , of an alternative embodiment with cooling units spread over the width of the strip,
FIG. 4 is a diagram, similar to FIG. 3 , of an alternative embodiment with cooling units split up over the width and length of the strip,
FIG. 5 is a diagrammatic vertical section of an example of a cooling section.
DETAILED DESCRIPTION
FIG. 1 is a diagram of an exemplary embodiment of a system A for supplying cooling liquid according to the invention for a unit DI . . . DIII ( FIG. 2 ) for spraying liquid onto a strip B to be cooled moving vertically downwards. Each unit DI . . . DIII is associated with a system A.
The system A controls the flow rate and temperature of the cooling water. The configuration of A comprises two separate circuits for supplying cold water 1 and hot water 2 , each equipped with a regulating valve CV 1 , CV 2 respectively and connected to a same outlet duct 3 . A flow rate controller CD for the mixture is provided on the duct 3 , as is a temperature controller TE for the mixture. A regulator R allows the proportion of the flow rates of the cold water and hot water to be adjusted so as to obtain the overall target flow rate of the liquid at the desired temperature, and to do so for each spraying unit, also called a cooling unit DI, DII, DIII ( FIG. 2 ).
In FIGS. 2 to 5 , the droplets of liquid atomized by each cooling unit are shown as a whole in the form of a prismatic sheet, the base of which is situated on the strip B, whereas the opposite edge corresponds to the liquid outlet nozzles of the cooling unit.
Controlling the temperature of the atomized water and/or controlling the atomization parameters according to the invention constitute additional means for controlling the flow rate of atomized water. These means make the cooling more flexible and more homogeneous.
According to the invention, the temperature of the cooling liquid and/or the atomization parameters are adjusted such that they differ between two successive cooling units DI, DII, DIII ( FIG. 2 ) in the direction in which the strip moves.
The device according to the invention makes it possible to control the temperature of the atomized water and/or the atomization parameters over the length of the cooling section by splitting up the cooling device lengthwise into cooling zones I, II, III ( FIG. 2 ). For each zone, a cooling unit is provided on each side of the strip, DI, D′I, . . . DIII, D′III respectively. Each cooling unit has a means for regulating the temperature of the liquid and/or a separate nozzle of the ejector from that of the other zones.
The device according to the invention also allows the temperature of the atomized water to be controlled over the width of the cooling section by, as illustrated in FIG. 3 , splitting up the cooling device widthwise into split-up cooling units DIa, DIb, . . . DIe, each having a means for regulating the temperature of the liquid which is separate from that of the other zones.
According to an exemplary embodiment of the invention, the temperature-regulating means forming the system A is a hot water/cold water mixer faucet supplied from a hot water network and a cold water network. The mixer faucet adjusts the proportion of the flow rates of cold water and hot water in accordance with the reference temperature.
According to another exemplary embodiment of the invention, the temperature-regulating means is a heat exchanger between the cooling liquid and another fluid, for example air or water.
It is also possible to control the temperature of the atomized water and/or the atomization parameters transversely in order to act on the thermal homogeneity over the width of the strip. The temperature of the cooling liquid and/or the atomization parameters are thus adjusted over the width of the strip, for example for a constant flow rate of the liquid, so as to maintain a vapor film over the entire width of the strip and to control the level of heat exchange.
FIG. 3 is a diagram of an exemplary embodiment according to the invention of this transverse regulation of the temperature of the cooling liquid, with 5 separate cooling units over the width of the strip.
As shown in FIG. 4 , this transverse regulation of the temperature of the cooling liquid can be implemented over the length of the strip so as to obtain more flexible regulation by adjusting the cooling parameters of the strip at all points of the cooling section.
The invention also relates to a cooling method such that the cooling curve is the target curve at each point of the width of the strip along the cooling section.
The adjustment of the temperature of the water also makes it possible to limit the risk of folds forming (cool buckle) at the beginning of the cooling. This risk may result from a large discontinuity in the slope in the thermal path of the strip when it passes from the heating section, or the temperature maintaining section, to the rapid cooling section. The patent FR 2802552 (or the U.S. Pat. No. 6,464,808) describes this problem in more detail.
By increasing the temperature of the water at the very beginning of the cooling, for example to 80° C., the invention makes it possible to limit the initial cooling of the strip and hence limits the risk of the formation of folds (cool buckle) as a result of a smaller discontinuity in the slope.
The invention thus also relates to a method for controlling the cooling of a moving metal strip in a continuous processing line which sprays onto the strip a liquid or a mixture consisting of a gas and a liquid, with the temperature of the liquid adjusted at the beginning of the cooling so as to limit the variation in the temperature slope resulting from the cooling, compared with heating or maintaining at the previous temperature.
For a same flow rate of cooling liquid, increasing its temperature according to the invention, for example from 40° C. to 60° C., enables cooling with smaller flows, which allows cycles with smaller cooling slopes, allowing increased flexibility of the cooling section.
The combined adjustment of the temperature and the flow rate of the cooling liquid makes it possible to modulate the thermal flow extracted from the strip.
According to the invention, as illustrated in FIG. 4 , the temperature and the flow rate of the cooling liquid are adjusted over the width and the length of the strip, so as to increase the flexibility of the plant by benefiting from a wider range within which the speed of the cooling of the strip is adjusted. The cooling units are split up widthwise (letter suffixes a, . . . e) and lengthwise (Roman numeral suffixes I, II, III) into individual units DIa, . . . DIIIe.
Also according to the invention, controlling the temperature profile over the width of the strip resulting from the adjustment of the cooling capacity over the width of the strip makes it possible to improve the guidance of the strip over the transporting rollers by the creation of long or short edges relative to the center of the strip.
Controlling the temperature profile over the width of the strip resulting from the adjustment of the cooling capacity over the width of the strip makes it possible to improve the flatness of the strip by controlling the length of the edges relative to the center of the strip.
Controlling the temperature profile over the width of the strip resulting from the adjustment of the cooling capacity over the width of the strip makes it possible to improve the stability of the strip by controlling the length of the edges relative to the center of the strip.
Advantageously, the adjustment of the cooling capacity over the length of the cooling section and over the width of the strip is carried out in real time by a control and command system (not shown) of the line by means of a calculator using mathematical models which take into account the progression of the heat exchange between the strip and its environment in the cooling section and in the section situated downstream therefrom. The calculator commands the regulating valves CV 1 , CV 2 of the different systems A.
The invention also consists in splitting the cooling device up both across the width and along the length of the strip into a plurality of units, as illustrated in FIG. 4 . Each unit is equipped with the equipment required to vary the temperature and the flow rate of the cooling liquid and/or the atomization parameters, independently of the other units.
The size of the cooling units DI . . . DIII can differ along the cooling section with a smaller size in the portion of the cooling section where the calefaction phenomenon may become unstable so as to better control the phenomenon. In this portion, the length of the cooling units can be smaller in the direction in which the strip moves. The width of the cooling units can also be reduced there, relative to the width of the strip.
In the case of cooling using a mixture consisting of a gas and a liquid, each unit can be equipped with two control means which make it possible to vary the flow rate of gas and the flow rate of the liquid.
Each unit can also be equipped with a device which makes it possible to vary the temperature of the gas, the liquid or the mixture consisting of the gas and the liquid so as to affect the calefaction phenomenon and vary the cooling capacity. This variation of the temperature of the cooling medium can be achieved for a constant flow rate of the cooling medium or combined with a variation of the flow rate of the cooling medium so as to increase the regulating flexibility of the plant.
The production capacity of a continuous line varies within large proportions depending on the size of the strip, in particular its thickness, and depending on the thermal cycle.
Depending on the production level, the flow rate of sprayed water will thus vary greatly, which makes it difficult to control for the large and small flow rates owing to the limited flexibility of the means for controlling the flow rate. In order to increase the precision with which the flow rate of water is regulated, the invention also consists in varying the temperature of the cooling liquid so as to limit the amplitude of variation of the flow rate of water.
Thus, according to the invention, for large-scale production necessitating very large cooling flows, cold water will be atomized so as to limit the flow rate of water, but for small-scale production, for example small thicknesses, slightly hotter water will be atomized so as to raise the necessary flow rate of water a little.
The invention thus also relates to a method for controlling the cooling of a moving metal strip in a continuous processing line which sprays the strip with a liquid or a mixture consisting of a gas and a liquid with a temperature of the liquid which is adjusted according to the target cooling capacity so as to limit the variations in the flow rate of the cooling liquid.
An exemplary embodiment, depicted in FIG. 5 and summarized below, creates the variations in the temperature of the cooling water according to the invention:
at the beginning of the cooling (zone DI, D′I), the metal strip is at 750° C. and the atomized water is at 80° C. so as to limit the risk of folds forming on the strip (cool buckle), the atomized water is then at 40° C. so as to obtain a rapid cooling throughout the zone (DII, DIII, DIV; D′II, D′III, D′IV) where the temperature of the strip is significantly greater than the Lindenfrost temperature, and then, in the critical zone (DV, DV′) or transition zone where the temperature of the strip is close to the Lindenfrost temperature, the temperature of the water is brought to 80° C. so as to preserve a vapor film for as long as possible. and finally, in the zone (DVI, D′VI) where the temperature of the strip is below the Lindenfrost temperature, the temperature of the water is returned to 40° C. so as to rapidly reach the required temperature of the strip (60° C.) at the end of the cooling.
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The invention relates to a method for monitoring the cooling of a moving metal belt (B) in a cooling section of a continuous processing line by spraying a liquid or a mixture consisting of a gas and a liquid onto the belt, the cooling depending on parameters including the temperature, speed, and current characteristics of a cooling liquid, wherein according to said method: one or more areas are determined in which cooling parameters are such that the local removal of a vapor film on the surface of the hot belt is carried out or capable being carried out, leading to the redampening of the belt; and at least the temperature of the cooling liquid is adjusted as a cooling parameter in the thus-determined area(s) so as to maintain, or return to, a cooling into a vapor film on the surface of the belt.
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BACKGROUND OF THE INVENTION
Embossing machines are increasingly used for producing identification cards and as a rule they are a part of a complex data processing system which frequently is directly coupled to an electronic data processing device. This occasions the requirements that such an embossing machine be electronically controlled and have a high operating speed.
In embossing machines of the type having a drum-like die head the major part of each cycle of operation is taken up by the time required for angular displacement of the die head to reach a selected position. Consequently, by reducing this setting period the greatest increase in the operating speed can be attained.
In known embossing machines, a reduction of the setting period is obtained by using a stepper motor as the driving motor. However, in order to accelerate and, above all, in order to brake relative heavy masses, a very large stepper motor has to be used. Moreover, a high electrical output is required to operate such a stepper motor. Therefore, because of economic considerations, the attainable increase in operating speed is limited.
Attempts also have been made to directly drive the die head by a direct current motor having a small armature and using the drive motor itself as a brake by means of a counter electromotive force (emf) when the selected position is approached or reached. The operating speed which can be obtained with such a scheme, however, is relatively small because the maximum braking moment is limited by the thermal conditions of the motor armature or the conditions of the commutator. Moreover, the electrical consumption for a system controlled in such a way is relatively large due to the relatively high mechanical time constant if there are oscillations. This would also consume time and would have to be avoided.
SUMMARY OF THE INVENTION
The present invention is concerned with an improved device of the aforementioned kind that will comply with the demands of the user by means of increased speed and with low-noise operation. In a device according to the instant invention the drive motor is a direct current motor with a coreless armature. Using such a drive motor, a maximum acceleration moment is attained if, in the range of its admissible thermal power, it is used exclusively to drive the die head. This requires that an especially efficient braking system be provided for stopping the high speed die head when its selected position is reached. It has been found that an electromagnetic disk brake is particularly suitable for this purpose. In the case where the disk brake is mounted on the shaft of the die drum, which gives an appropriate performance, with such an electromagnetic disk brake, the die drum can be reliably stopped within a short period when the selected position is reached, even at high rotational speed. Therefore, a high operating speed for the setting operation and, consequently, a reduction of the setting period are attained. Moreover, during the operation an extremely low-noise braking of the die drum is attained by using this electromagnetic disk brake. This meets the practical needs because such embossing machines will be used, for instance, in hospitals, clinics or consulting rooms of a medical practioner in order to automatically evaluate the identification means of a health insurance company. So, in such areas, noise reduction is of a considerable importance.
When disk brakes are used, the brake operation itself is nearly noiseless. In the field of application for embossing machines the difficulty resides in that the stopping of a die drum which is provided, for instance, with 96 pairs of dies, must be performed within an angle or rotation of less than 3.75 degrees. This means that for the desired operating speed of the embossing machine (approximately 200 to 300 embossing per minute depending upon the typing speed of an efficient operator) the braking of the die drum will have to be performed in only 1.5 to 2 milliseconds (ms). As a consequence, an actuating element has to be used for the disk brake which is adopted to press the brake lining against the brake disk in this extremely short period and under a pressure of about 1,500 to 2,000 Newton. This can be attained by an electromagnetic braking system according to the invention when the coil of the electromagnet is supplied with a braking impulse of about 50 to 100 times nominal voltage.
The high increase of the magnetic force attained in this manner has the effect that the armature, if this can freely move, will be highly accelerated and, consequently, the pressure plate associated with it which is provided with the brake lining, will strike against the brake disk at high speed when there is only small displacement. Naturally, this would cause a loud noise.
According to the invention, the magnetic driving system for the disk brake is constructed in such a way that the clearance between the armature and the electromagnet is selected to be as small as possible so that the necessary magnetic forces can be attained by a reasonable electrical expenditure (in practice the clearance is about 0.5 mm) and that, moreover, the movable part of the braking system, when in its inactive or home position, is pressed by means of springs which act in the same direction as the magnetic forces, which is the axial direction, against the elastically mounted brake disk so that this also engages a second brake lining under slight pressure.
Consequently, during the setting operation, the die drum is slightly braked, however, this braking is negligible. When the braking impulse is received, an electromagnetic field, with a corresponding magnetic force, is created between the armature and the electromagnet which is transmitted to the brake disk practically without any movement of the armature. If the magnet support has sufficient mechanical rigidity, under the respective forces, springiness will be attained within a range of about 0.02 to 0.03 mm, so that no noticeable noise is formed.
For such an arrangement, it is difficult to apply the brake lining directly to the armature. Therefore, it is suitable to connect the armature through a parallel guide means, which defines a direction of movement perpendicular to the brake disk, to a pressure plate which is provided with the brake lining. Consequently, a considerable higher degree of constructional freedom as to the arrangement of the parts can be obtained. Particularly, a corresponding construction of the parallel guide means enables an independent adjustment of the pressure plate and the armature. Appropriately, moreover, there will be an additional possibility of adjustment for the armature with respect to its position as to the electromagnet and, eventually, the position of the brake lining as to the brake disk can be simultaneously pre-set.
Appropriately, an elastic coupling having high self-damping is arranged between the disk brake and the die drum. Thereby the effective moment at the brake disk is reduced. Moreover, the characteristic frequency of such an elastic coupling or its oscillatory system, respectively, can easily be selected so that the oscillations will have been damped out before the die drum becomes locked in its selected position.
A further reduction of the force to be absorbed by the disk brake and, therewith, an increase in the operating speed or a reduction of the setting period, respectively, can be attained by providing a friction clutch between the drive motor and the die drum. In this case the friction clutch will be adjusted as to a transmission moment which is only slightly more than the maximum moment, i.e. the starting moment of the drive motor. Thus, a considerable component of the kinetic energy of the drive motor will be absorbed by the friction clutch during the braking operation. In such a way the electromagnetic disk brake will be considerably relieved. It has to be emphasized that in practice the moment of inertia of the die drum and that of the drive motor with respect to the die drum can be of the same magnitude. This means, that the double energy would have to be absorbed by the disk brake. However, the constant moment which is transmitted by the friction clutch is only 10% of the braking moment to be applied by the electromagnetic disk brake. Therefore, under otherwise the same conditions, a further increase in the operational speed is attained by the arrangement of said friction clutch between the drive motor and the die drum.
BRIEF DESCRIPTION OF DRAWING
In the drawing an embodiment of the present invention is illustrated, wherein:
FIG. 1 is a diagramatic view of a driving and braking system for an electronic embossing machine in accordance with the principles of the invention;
FIG. 2 is a perspective view with cut-out portions of an embodiment of an elastic coupling arranged that may be used with the system of FIG. 1 with parts removed for clarity;
FIG. 3 is a partial end view of the embodiment as shown in FIG. 2 taken along the lines 3--3;
FIG. 4 is a diagram illustrating the characteristic of the elastic coupling shown in FIG. 2; and
FIG. 5 is a perspective view with cut-out portiions of a braking device for the system of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a die drum 10 of an embossing machine has embossing dies 10' disposed therein and is mounted on a die drum shaft 11. The die drum 10 is driven by a drive motor 12 through two transmission gears 13, 13'. The transmission gears 13, 13' reduce the number of revolutions of the electric motor 12 serving as a drive motor in the ratio of 1:10 because electric motors have their favorable efficiency only when driven at a relative high speed.
As a consequence of this high step down gearing the inertial moment of the motor armature effective at the shaft 11 of the die drum 10 will be multiplied with the square of the gear ratio. This results in considerable difficulty in the braking operation of the die drum 10 when the selected embossing position is reached, thereby increasing the stopping time or stopping distance. A respective reduction of the number of revolutions of the die drum 10, however, again would reduce the operating speed during the setting operation.
Therefore, between the transmission of the force of the drive motor 12 to the die drum 10 through the transmission gears 13, 13', 13", 13'", a friction clutch 14 is arranged which is only schematically indicated in FIG. 1. This friction clutch 14 is adjusted to a transmission moment that is only slightly more than the maximum moment of the drive motor 12. Thus a considerable component of the kinetic energy of the drive motor 12 is absorbed by the friction clutch 14 when the drive motor is disabled, at which time the friction clutch is actuated. The inertial moment of the drive motor 12 effective at the shaft 11 of the die drum 10, which in the practical operation can reach the magnitude of the inertia moment of the die drum, therefore, will no longer double the to be braked kinetic energy. The constant moment transmitted from the drive motor 12 through the friction clutch 14 to the shaft 11 of the die drum is now only about 10% the braking moment required to stop the die drum 10 at the selected embossing position and which has to be applied by the electromagnetic brake. Thus the drive motor 12 and the die drum 10 can be allowed to have a considerably high number of revolutions per minute (r.p.m.) without any disadvantage with respect to the stopping period.
The brake system comprises a brake disk 15 mounted on the shaft 11 and an electromagnetically actuated brake device 16, in the form of an electric clutch, that is supported by a housing 16'. The electric clutch 16 acts upon the peripheral area of the disk 15 on both sides thereof as will be described more fully hereinafter. The brake disk 15 and the brake device 16 constitute the disk brake. In addition to the brake disk 15, a control disk 17 is mounted at the shaft 11 of the die drum 10. This control disk 17 is used to supply the information relative to the position of the die drum 10 and is scanned by a sensor 18, such as a light sensor, which is attached to the housing 16' and which controls the brake device 16. The control disk 17 has a plurality of radially encoded openings 17' that serve as indicators for the orientation of said die head 10. When the drive motor 12 is started, the die drum 10 will rotate until an electric control of a known kind, as for example shown in German Patent DE-05 No. 2518 590, ascertains at the sensor 18 that the die selected for embossement has arrived at the embossing position. Then an electrical impulse is supplied to the brake device 16, the impulse having as high a power as can be obtained, for instance, by discharging a capacitor with 50 to 100 times nominal voltage of the coil.
Thereby the brake disk 15 of the disk brake will be stopped within about 1.5 ms. Based on the elastic coupling 19 to be described more fully hereinafter, disposed upon the shaft 11 of the die drum between the disk brake and the die drum 10, the die drum can perform only one or two highly dampened oscillations of high characteristic frequency and will then come to rest.
When the electrical impulse is supplied to the brake device 16, simultaneously the motor 12 is disabled the friction clutch 16 is actuated and a one-revolution-clutch 43 of a driver 44, which is shown in FIG. 1, is also actuated. Through this actuation, the driver 44 becomes coupled to a control cam 20 so that a pawl 21 will be released and under the effect of a tension spring 22 will engage a gap between the teeth of the transmission gear 13'" mounted at the shaft 11 of the die drum in order to urge the die drum 10 into the exact embossing position.
Based on the elastic coupling 19 having as high a self-damping as possible and arranged between the die drum 10 and the disk brake, the braking moment is further reduced if the characteristic frequency of the oscillatory system is selected so that oscillations of the part as illustrated in the FIG. 1 on the left side of the elastic coupling 19 will already have been practically damped out when the pawl 21 comes into its engagement position.
FIGS. 2 and 3 illustrate a possible embodiment of the construction of the elastic coupling 19. A driver 23 is fixed to the shaft 11 of the die drum 10. The driver 23 is provided with two radially projecting circular section lugs 24, 24'. The brake disk 15 is fixed to the elastic coupling 19 which comprises two pairs of diametrically opposite noses 26, 26'; 27, 27', being arranged in the nose and axle cross manner, and a buffer medium 29 is inserted in the respective gaps. One of the pairs of diametrically opposite noses 26, 26' is solid, i.e. massive. The second pair of diametrically opposite noses 27, 27' is provided with circular section slots 28, 28'. These slots 28, 28' of the slotted noses 27, 27' receive, with play, projections 24, 24' of a driver 23. The plane of the slots 28, 28', therefore, is perpendicular to the axis of the shaft 11 of the die drum 10. More details will be apparent from the drawing. The buffer medium 29 is made out of an elastic material and pre-stressed to be pressed into the gaps, between the noses 26, 26' or 27, 27' respectively, arranged in a nose and axle cross manner. The buffer medium, therefore, is over-sized.
Furthermore, in order to improve the transmission of force between the projections 24, 24' and the slots 28, 28' of the slotted noses 27, 27' on their sides facing the projections 24, 24', metal plates 30 are fixed to the buffer medium 29. Based on this, the surface pressure is reduced and, moreover, the projections 24, 24' will be prevented from cutting into the elastic material of the buffer means.
In FIG. 4 a characteristic of such an elastic coupling is illustrated. As is apparent, in spite of the application of elastomers with a high instrinsic friction, i.e. with a considerable hysteresis between charging and discharging, a very exact rest or zero position can be attained for the clutch and simultaneously a considerable absorbtion of kinetic energy takes place which in turn relieves the disk brake.
The disk brake system comprises the brake disk 15 and an electromagnetic brake device 16. Appropriately, the brake disk 15 is formed very thin and made out of steel and provided with apertures 15' in order to make its rigidity in the axial direction as small as possible.
Referring now to FIG. 5, the electromagnetic brake device 16 comprises a carrier 31, having, for example, an E-shaped form, which is stationarily mounted on the housing 16', and which is provided with three horizontal arm sections, the upper arm section 32, the middle arm section 33 and the lower arm section 34. The upper arm section 32 receives at its lower surface, which faces the brake disk 15, an upper brake lining 35. The middle arm section 33 carries the electromagnet 36 and is, moreover, provided with the bearings 37 which serve as guides that are disposed upon bars 38 which connect an armature plate 39 mounted opposite the electromagnet 36 with a pressure plate 40 having a brake lining 35' on its surface facing the brake disk 15. The pressure plate 40, therefore, is arranged within the space between the upper and the middle arm sections 32, 33, respectively, and beneath the brake disk 15, which is received therebetween, and it is movable together with the armature 39 in the direction which is perpendicular to the surface of the brake disk and parallel to the axis of the shaft 11 of the die drum 10.
The armature 39 is arranged within the space between the middle and lower arm section 33, 34, respectively, below and in front of the electromagnet 36 which depends from the middle arm section 33. The armature 39 is supported by two pressure springs 41, 41' which extend from the lower arm section 34 in the direction parallel to the axis of the die drum shaft 11.
The carrier 31 is mounted on the housing 16' and is adjustable so that the upper brake lining 35 is in sliding contact, with a slight pressure, with the brake disk 15. Subsequently, the armature 39 is lifted by means of the adjustment screws 42, 42' through pressure springs 41, 41' so that the lower brake lining 35' is also in sliding contact with the brake disk 15 under slight pressure. Both the brake linings 35 and 35', therefore, are slightly engaged, with slight pressure, with the brake disk 15. This insignificant permanent braking of the die drum 10, however, will be neglectible during operation.
During the adjustment of the adjustment screws 42, 42', the armature 39 simultaneously approaches the electromagnet 36 and will be advanced until only a small clearance, such as 0.5 mm or less, remains. Thus, the armature 39 will already be directly in front of the magnetic coil and virtually does not move when the braking impulse arrives and, therefore, no impact noise will be caused. The remaining small amplitude of movement, however, will be sufficient to increase the pressure of the brake linings 35, 35' to the brake disk 15 and, therefore, to obtain the braking effect.
The distance of the armature 39 to the pressure plate 40 can, eventually, be adjusted by means of a change of the length of the bars 38, so that the slight engagement of the brake lining 35' at the brake disk 15 and simultaneously the arrangement of the armature 39 directly in front of the electromagnet 36 will reliably be ensured.
Therefore, a very high r.p.m. of the die drum 10, and thereby, a respective high setting speed is possible without any danger than the exact embossing position might be affected. By using the efficient disk brake comprising the brake disk 15 and the brake device 16, a speedy stopping at the embossing position is assured also for a high number of revolutions per minute and this operation also will be enhanced by action of the friction clutch 14 and the elastic clutch 19. A driving and braking system of the proposed system will cause only low noise.
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This invention relates to a driving and braking system for an electronically controlled embossing machine of the type having a rotatable drum that carries embossing dies. A drive motor is provided for rotating the drum and a brake is included for stopping the drum in selected embossing positions. The brake includes a disk and a brake lining which are in slight engagement with one another during rotation of the drum so that when the brake is actuated the parts thereof have a small distance to travel.
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BACKGROUND OF THE INVENTION AND RELATED ART
The present invention relates to a cold cathode type flat panel display, in particular, a spontaneously emitting type flat panel display using cold cathode electron sources.
As known well, a cold cathode type flat panel display is a display that comprises a phosphor film which is formed on a flat panel and emits by electron excitation and very small cold cathode electron sources arranged in a two-dimensional matrix form so as to be opposed to the phosphor film, and that has a function of irradiating the phosphor film with electron rays emitted from the electron sources to display an image on the panel. Displays using such very small cold cathode electron sources which can be integrated are generically named field emission displays (FEDs).
Cold cathode electron sources are roughly classified to field emission type electron sources and hot electron type electron sources. Examples of the former include a spindt type electron source, a surface conduction type electron source, and a carbon nano-tube type electron source. Examples of the latter include a metal-insulator-metal (MIM) type electron source, wherein a metal, an insulator and a metal are laminated, and a metal-insulator-semiconductor (MIS) type electron source, wherein a metal, an insulator and a semiconductor are laminated.
The MIM type electron source is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-101965 (Patent Document 1) and Japanese Patent Application Laid-Open 2000-208076 (Patent Document 2). A structure of the MIM electron source and the operation principle thereof are shown in FIGS. 1 and 2 .
FIG. 1 is a sectional structural view of an MIM type electron emitting element. In FIG. 1 , bottom electrodes 11 , made of, e.g., Al or Al alloy, are formed on an insulating cathode substrate 10 made of glass or the like so as to have a thickness of, e.g., 300 nm and be in a stripe form in the direction perpendicular to the surface of the drawing paper.
An interlayer insulator 14 (film thickness: e.g., 140 nm) for preventing the concentration of an electric field at edges of the bottom electrodes 11 and limiting or laying down an electron emission area, and a tunneling insulator 12 (film thickness: e.g., 10 nm) are formed.
Contact electrodes 15 and top electrode bus lines 16 are formed in a stripe form in the direction perpendicular to the bottom electrodes 11 (i.e., the right and left direction in the drawing paper), so as to avoid the electron emission area E. The electron emission area E corresponds to top electrodes 13 on the tunneling insulator 12 . The top electrodes will be described in detail later.
The contact electrodes 15 are made of a metal film having a strong adhesive force to the cathode substrate 10 or the interlayer insulator 14 , for example, a high melting point metal such as W (tungsten) or Mo (molybdenum) or a silicon compound thereof (silicide), so as to have a film thickness of, e.g., about 10 nm.
The top electrode bus lines 16 are bus lines which can be connected to the top electrodes 13 , which will be detailed later, at a low resistance and are made of an Al—Nd alloy film, so as to have a thickness of 200 nm. In order to prevent the snapping of the top electrodes 13 , which will be detailed later, it is desired that a metal film as an underlying layer 15 A for the contact electrodes is made as thin as possible.
On the top electrode bus lines 16 , the interlayer insulator 14 and the cathode substrate 10 except the electron emission area E, a surface protection film 17 is formed, which is an insulator film made of, for example, intrinsic silicone, SiO 2 , glass (such as phosphor doped glass or boron doped glass) , Si 3 N 4 (nitride) , Al 2 O 3 (alumina) or polyimide. For reference, in the case of using Si 3 N 4 , the film thickness thereof is from 0.1 to 1 im.
The tunneling insulator 12 is covered with top electrodes 13 . The top electrodes 13 have a three-layer structure composed of a lower layer made of Ir (iridium), which is good in heat resistance, an intermediate layer made of Pt (platinum) and an upper layer made of Au (gold), which is good in electron emitting efficiency, and are applied onto the tunneling insulator 12 in a thin film forming step using, for example, sputtering.
In this thin film forming step, the layer of the top electrodes 13 is simultaneously deposited on the surface of the surface protection film 17 . As shown in FIG. 1 , however, the layer of the top electrode bus lines 16 retreats inwards from end faces of the surface protection film 17 so that the surface protection film 17 is made into the form of eaves. Consequently, a metal film 13 ′ on the surface protection film 17 is electrically insulated from the top electrodes 13 on the tunneling insulator 12 .
When a voltage Vd is applied between the bottom electrodes 11 and the top electrodes 13 of the MIM type electron emitting element having a structure as described above in vacuum, electrons, in the bottom electrodes 11 , having an energy level near the Fermi level penetrate through a potential barrier by tunneling phenomena, so as to be injected into the conduction band of the tunneling insulator 12 and the top electrodes 13 . As a result, hot electrons are generated. Among these electrons, electron having a kinetic energy equal to or more than the work function φ of the top electrodes 13 are emitted into the vacuum.
A document related to such a technique is Japanese Patent Application Laid-Open No. 2001-83907 (Patent Document 3).
FIG. 46 is a sectional view illustrating an outline of a display panel in the prior art. As illustrated in this figure, in order to use the above-mentioned MIM type electron sources to construct a display device, the cathode electrode 10 wherein the electron sources having the structure illustrated in FIG. 1 are arranged in a matrix form and an anode substrate 110 wherein phosphor film pieces 111 are arranged in a matrix form so as to correspond to the electron source elements of the cathode substrate 10 are adhered through a glass frame member 116 made of glass or the like by junction based on frit glass 115 , thereby making an inner space 118 into vacuum. In this way, a display panel (flat panel display) 120 is yielded. As will be described in more detail later, the anode substrate 110 is made of a light-transmitting flat panel, and the whole of a single surface of the anode substrate 110 , including the surfaces of the phosphor film pieces 111 , is covered with a conductive film (called a metal back) 114 .
When the diagonal size of the display panel 120 is more than 5 inches in this case, it is necessary to insert spacers 30 made of an insulator material, as reinforcing materials, at intervals of several centimeters into the inner space (vacuum atmosphere) of the panel in order to keep the atmospheric pressure.
A part of electrons emitted from the electron source elements collides with these spacers 30 , so that the spacers 30 are charged up. Near the charged spacers, the orbit of the electrons is curved so as to cause a phenomenon that an image is distorted. In order to prevent this phenomenon, a slight conductivity is given to the surface of the spacers 30 by means of a high-resistance film made of tin oxide, a mixed crystal thin film made of tin oxide and indium oxide, a metal film, a semiconductor film or some other film. In this way, the electrification of the spacer surfaces is removed.
It is therefore necessary to connect the spacers 30 electrically to the metal back 114 on the side of the anode substrate 110 and the top electrodes 13 ′ on the surface protection film 17 on the side of the cathode substrate 10 . The top electrodes 13 ′ for giving grounding voltage on the side of the cathode substrate 10 have a thickness of 10 nm or less and further have a weak adhesive force to the surface protection film 17 ; therefore, when pressure from the spacers is applied to the top electrodes 13 ′, the snapping or breaking down thereof is easily caused. In order to prevent this, it is necessary to set third bus lines independently of the data lines (the top electrode bus lines 16 and the scan lines (the bottom electrodes 11 ), as ground lines 18 for the spacers 30 , on the surface protection film 17 .
However, in the case of adopting the three-layer line structure wherein the data lines 16 , the scan lines 11 and the third bus lines independently thereof are set on the side of the cathode substrate 10 as described above, the production process thereof unavoidably becomes longer than the production process including the formation of two-layer bus lines. As a result, problems of a drop in the yield or an increase in the production costs are caused.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve the above-mentioned problems and provide a cold cathode type flat panel display (specifically, a hot electron type cold cathode type flat panel display) comprising a cathode substrate which has a two-layer structure but substantially has ground lines for spacers which can be inexpensively produced.
As a result of various experiments and examinations, the inventors have obtained the finding that the above-mentioned problems can be solved by taking the following measurements: a cathode substrate which has a two-layer line structure but substantially has ground lines, for spacers, having a stable structure can be realized by contriving its line structure as follows:
(1) Hitherto, bottom electrodes, which are first layer (lower layer) lines used as scan lines, are made into data lines (conventional scan lines are converted to data lines), and (2) Spacer lines and scan lines made of second layer lines (top electrode bus lines) are formed so as to display an image according to a line sequential scanning scheme (conventional data lines are converted to scan lines).
First, by the item (1), the scan data and the spacer lines can be extended in the same direction. In addition, the second lines are used to make the scan lines and the spacer lines from the same layer.
Questions may be put up to the practicability of the above-mentioned line structure. However, the present invention has a sufficient basis.
In general, the shape of each of pixels is a square. A scan line pitch corresponds to the length of each side of this square. The pitch of data lines is ⅓ of the length since each of the pixels includes three colors, that is, red (R), green (G) and blue (B). Specifically, for example, in a WXGA (resolution: 720×1200 dots) having a diagonal size of 32 inches, the scan data pitch thereof and the data line pitch thereof are 550 im and 183 im, respectively.
Since the thickness of ordinary spacers themselves is from about 100 to 200 im, it can be said that the structure of the present invention, wherein spacers and ground lines for the spacers are inserted between scan lines having a wide pitch, is a reasonable design.
When the above is summarized, the following conclusion can be obtained: by adopting the present invention, lines composed of three layers in the conventional cathode substrate 10 are unified into lines composed of two layers; accordingly, the interlayer insulator present between the third lines and the second lines in the cathode substrate 10 becomes unnecessary.
As described above, according to the present invention, the line structure of its cathode substrate is changed from the three-layer line structure in the prior art to a two-layer line structure and further ground lines for its spacers are formed, as the same layer as is made up to top electrode bus lines which constitute scan lines, on the same flat surface. Therefore, the line structure is simple and further the top electrode bus lines and the ground lines for the spacers can be produced in the same step. As a result, the production process of the display of the present invention can be shortened and an improvement in the yield thereof and a drop in the production costs thereof can be attained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view illustrating an MIM type electron source in the prior art.
FIG. 2 is a view illustrating the operation principle of the MIM type electron source.
FIG. 3 is a plan view illustrating the step of forming a bottom electrode 11 in the production of an MIM type electron source of the present invention.
FIG. 4 is a sectional view of the members illustrated in FIG. 3 , taken on line A-A′, in the production of the MIM type electron source of the present invention.
FIG. 5 is a sectional view of the members illustrated in FIG. 3 , taken on line B-B′, in the production of the MIM type electron source of the present invention.
FIG. 6 is a plan view illustrating the step of forming a tunneling insulator 12 on the bottom electrode 11 in the production of the MIM type electron source of the present invention.
FIG. 7 is a sectional view of the members illustrated in FIG. 6 , taken on line A-A′, in the production of the MIM type electron source of the present invention.
FIG. 8 is a sectional view of the members illustrated in FIG. 6 , taken on line B-B′, in the production of the MIM type electron source of the present invention.
FIG. 9 is a plan view illustrating the step of forming contact electrodes 15 A and 15 B in the production of the MIM type electron source of the present invention.
FIG. 10 is a sectional view of the members illustrated in FIG. 9 , taken on line A-A′, in the production of the MIM type electron source of the present invention.
FIG. 11 is a sectional view of the members illustrated in FIG. 9 , taken on line B-B′, in the production of the MIM type electron source of the present invention.
FIG. 12 is a plan view illustrating the step of forming top electrode bus lines 16 and spacer lines 16 ′ in the production of the MIM type electron source of the present invention.
FIG. 13 is a sectional view of the members in FIG. 12 , taken on line A-A′, in the production of the MIM type electron source of the present invention.
FIG. 14 is a sectional view of the members in FIG. 12 , taken on line B-B′, in the production of the MIM type electron source of the present invention.
FIG. 15 is a plan view illustrating the step of producing the MIM type electron source of the present invention.
FIG. 16 is a sectional view of the members illustrated in FIG. 15 , taken on line A-A′, in the step of producing the MIM type electron source of the present invention.
FIG. 17 is a sectional view of the members illustrated in FIG. 15 , taken on line B-B′, in the step of producing the MIM type electron source of the present invention.
FIG. 18 is a plan view illustrating the step of producing the MIM type electron source of the present invention.
FIG. 19 is a sectional view of the members illustrated in FIG. 18 , taken on line A-A′, in the step of producing the MIM type electron source of the present invention.
FIG. 20 is a sectional view of the members illustrated in FIG. 18 , taken on line B-B′, in the step of producing the MIM type electron source of the present invention.
FIG. 21 is a plan view illustrating the step of producing the MIM type electron source of the present invention.
FIG. 22 is a sectional view of the members illustrated in FIG. 21 , taken on line A-A′, in the step of producing the MIM type electron source of the present invention.
FIG. 23 is a sectional view of the members illustrated in FIG. 21 , taken on line B-B′, in the step of producing the MIM type electron source of the present invention.
FIG. 24 is a plan view of a cathode substrate 10 of the present invention.
FIG. 25 is a sectional view of the cathode substrate 10 of the present invention, taken on line A-A′ of FIG. 24 .
FIG. 26 is a sectional view of the cathode substrate 10 of the present invention, taken on line B-B′ of FIG. 24 .
FIG. 27 is a plan view illustrating the production process of an anode substrate 110 using MIM type electron sources of the present invention.
FIG. 28 is a sectional view illustrating the production process of the anode substrate 110 using the MIM type electron sources of the present invention, taken on line A-A′ of FIG. 24 .
FIG. 29 is a sectional view illustrating the production process of the anode substrate 110 using the MIM type electron sources of the present invention, taken on line B-B′ of FIG. 24 .
FIG. 30 is a sectional view illustrating the production process of a display device using the MIM type electron sources of the present invention, taken on line A-A′ similar to the line in the cathode substrate 10 .
FIG. 31 is a sectional view illustrating the production process of a display device using the MIM type electron sources of the present invention, taken on line B-B′ similar to the line in the cathode substrate 10 .
FIG. 32 is a plan view of a display device schematically illustrating the state of line-connection between a display panel 120 of the present invention and driver circuits.
FIG. 33 is a diagram showing driving voltage waveforms in the display device of the present invention.
FIG. 34 is a plan view of a display device schematically illustrating the state of line-connection between a display panel 120 of the present invention and driver circuits.
FIG. 35 is a plan view of a display device schematically illustrating the state of line-connection between the display panel 120 of the present invention and driver circuits.
FIG. 36 is a plan view illustrating a different production process of the MIM type electron sources of the present invention.
FIG. 37 is a sectional view illustrating the different production process of the MIM type electron sources of the present invention, taken on line A-A′ of FIG. 36 .
FIG. 38 is a sectional view illustrating the different production process of the MIM type electron sources of the present invention, taken on line B-B′ of FIG. 36 .
FIG. 39 is a plan view illustrating the production process of the cathode substrate 10 , which is the different example of the present invention.
FIG. 40 is a sectional view illustrating the different example of the MIM type electron sources of the present invention, taken on line A-A′ of FIG. 39 .
FIG. 41 is a sectional view illustrating the different example of the MIM type electron sources of the present invention, taken on line B-B′ of FIG. 39 .
FIG. 42 is a sectional view illustrating the production process of the display device, which is the different example using the MIM type electron sources of the present invention, taken on line A-A′.
FIG. 43 is a sectional view illustrating the production process of the display device, which is the different example using the MIM type electron sources of the present invention, taken on line B-B′.
FIG. 44 is a plan view of a display device schematically illustrating the state of line-connection between the display panel 120 , which is the different example of the present invention, and driver circuits.
FIG. 45 is a diagram illustrating driving voltage waveforms in the display device which is the different example of the present invention.
FIG. 46 is a sectional viewing illustrating a display panel using an MIM type electron source in order to describe the prior art.
Reference numbers in the above-mentioned drawings are as follows. 10 : cathode substrate, 11 : bottom electrode (data line), 12 : tunneling insulator, 13 and 13 ′: top electrode, 14 : interlayer insulator, 15 : contact electrode, 16 : top electrode bus line (scan line), 16 ′: spacer line, 17 : surface protection film, 18 : spacer ground line, 20 : vacuum level, 30 : spacer, 40 : data line driver circuit, 50 : scan line driver circuit, 60 : high voltage generating circuit, 70 : flexible printed circuit (FPC), 110 : anode substrate, 111 : red phosphor, 112 : green phosphor, 113 : blue phosphor, 114 : metal back, 115 : frit glass, 115 ′: conductive frit glass, 116 : glass frame, 117 : black matrix, 118 :vacuum, 120 : display panel, E: electron emission area, and e: emitted electron.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
A first aspect of the present invention is typically a cold cathode type flat panel display which is an image display device comprising a vacuum panel container composed of a cathode substrate in which plural cold cathode type electron sources are arranged at regular intervals, an anode substrate in which a phosphor film is deposited in the form of dots or lines so as to be opposed to the electron sources, plural spacers for supporting the cathode substrate and the anode substrate at a given interval, and a glass frame.
Plural electrical lines which extend in a line direction and a row direction which cross each other are formed, across an interlayer insulator, on the cathode substrate; the cold cathode type electron sources are arranged at positions corresponding to intersection coordinates of these electrical lines so as to be connected to the electrical lines in the line direction and the row direction; and the cold cathode type electron sources are line-sequentially scanned, thereby displaying images.
In this image display device, some parts of lines positioned in the upper layer out of the plural electrical lines are made into scan lines and lines positioned in the lower layer out of the plural electrical lines are made into data lines, and
some parts of the electrical lines positioned in the upper layer are made into ground lines for giving ground voltage to the spacers, and further the spacers are in a ground state by the ground lines at the least in the period when the scan lines adjacent thereto are selected.
A second aspect of the present invention is typically a cold cathode type flat panel display which is an image display device comprising a vacuum panel container composed of a cathode substrate in which plural cold cathode type electron sources are arranged at regular intervals, an anode substrate in which a phosphor film is deposited in the form of dots or lines so as to be opposed to the electron sources, plural spacers for supporting the cathode substrate and the anode substrate at a given interval, and a glass frame.
Plural electrical lines which extend in a line direction and a row direction which cross each other are formed, across an interlayer insulator, on the cathode substrate; the cold cathode type electron sources are arranged at positions corresponding to intersection coordinates of these electrical lines so as to be connected to the electrical lines in the line direction and the row direction; and the cold cathode type electron sources are line-sequentially scanned, thereby displaying images.
In this image display device, lines positioned in the upper layer out of the plural electrical lines are made into scan lines and lines positioned in the lower layer out of the plural electrical lines are made into data lines, and
some parts of the scan lines positioned in the upper layer function both as power feeding lines for giving electric potential to the spacers and scan lines, and are at scan line voltage at the least in the period when the parts of the scan lines are selected.
A third aspect of the present invention is as follows: in the cold cathode type flat panel display according to the first or second aspect, in an edge portion of the cathode substrate, terminals of the electrical lines positioned in the upper layer are connected to a flexible printed circuit (abbreviated to FPC) connected to a scan line driver circuit, and supply electric potential to the spacer lines through the scan line driver circuit.
A fourth aspect of the present invention is as follows: in the cold cathode type flat panel display according to the first aspect, in an edge portion of the cathode substrate, terminals of the electrical lines positioned in the upper layer are connected to a flexible printed circuit connected to a scan line driver circuit, and supply ground voltage from the outside through independent power feeding lines in the state that the spacer lines are mutually short-circuited through internal lines of the flexible printed circuit.
A fifth aspect of the present invention is as follows: in the cold cathode type flat panel display according to the first aspect, the spacer lines in the edge portion of the cathode substrate are extended to the outside of terminals of the scan lines and are mutually short-circuited, and the spacer lines give ground voltage from the outside through independent power feeding lines.
A sixth aspect of the present invention is as follows: in the cold cathode type flat panel display according to any one of the first to fifth aspects, the cold cathode type electron sources each have a structure wherein a bottom electrode, an electron accelerator, and a top electrode are laminated in this order, and are each an electron source element which emits electrons from the surface of the top electrode when a positive voltage is applied to the top electrode.
A seventh aspect of the present invention is as follows: in the cold cathode type flat panel display according to the sixth aspect, the bottom electrode of each of the cold cathode type electron sources is made of Al or Al alloy, and the electron accelerator is made of alumina obtained by subjecting the Al or Al alloy to anodic oxidation.
EXAMPLES
An example of the present invention will be specifically described with reference to the attached drawings hereinafter.
Example 1
An example according to the first aspect of the present invention will be described with reference to FIGS. 3 to 33 .
(1) Formation of a Cathode Substrate 10 :
This item describes a production process in a case in which top electrodes 13 are connected electrically to contact electrodes 15 and further top electrode bus lines 16 are backed with aluminum, aluminum alloy, or a metal having a lower resistivity than aluminum.
It is beforehand stated that the MIM electron source producing process which can be used in the present invention is not limited to the present example. The present invention can easily be applied to MIM electron sources disclosed in Patent Documents 1 and 2 (Japanese Patent Application Laid-Open Nos. 2001-101965 and 2000-208076), which comprise top electrode bus lines having a tapered structure, and other MIM electron sources.
First, a metal film for bottom electrodes 11 is deposited on an insulating cathode substrate 10 made of glass or the like. As the material for the bottom electrode, Al or Al alloy is used. Actually, Al—Nd doped with 2% by atom of Nd was used. For the formation of the metal film, for example, sputtering is used. Actually, the film thickness thereof was set to 300 nm. After the formation of the metal film, the bottom electrodes 11 , in a stripe form as illustrated in FIG. 3 (a plan view), FIG. 4 (a sectional view taken on line A-A′), and FIG. 5 (a sectional view taken on line B-B′) are formed through a photolithographic step and an etching step. In the etching step, there is used, for example, wet etching based on an aqueous mixed solution of phosphoric acid, acetic acid and nitric acid.
As illustrated in FIG. 6 (a plan view), FIG. 7 (a sectional view taken on line A-A′), and FIG. 8 (a sectional view taken on line B-B′), the surfaces of the bottom electrodes 11 are subjected to anodic oxidation. For example, when the formation voltage is set to 6V, an insulator layer 12 having a thickness of about 10 nm is formed on the bottom electrodes 11 .
As illustrated in FIG. 9 (a plan view), FIG. 10 (a sectional view taken on line A-A′), and FIG. 11 (a sectional view taken on line B-B′), Si 3 N 4 for an interlayer insulator 14 , Cu for an upper contact electrode layer 15 B, which will be a seed film for plating, and Cr for a lower contact electrode layer 15 A for ensuring adhesiveness between Cu and the underlying thereof are continuously deposited by sputtering. The lower contact electrode layer 15 A is made as thin as about several ten nanometers in such a manner that the snapping of top electrodes 13 , which will be formed later, will not be caused by difference in level in the lower contact electrode layer 15 A. The film thickness of the upper contact electrode layer 15 B is not particularly limited. However, the film thickness is set in such a manner that the lower contact electrode layer 15 A will not elute out at the time of plating treatment.
As illustrated in FIG. 12 (a plan view), FIG. 13 (a sectional view taken on line A-A′), and FIG. 14 (a sectional view taken on line B-B′), resist patterns as plating masks are given to the upper contact electrode layer 15 B, and subsequently Cu is thickly deposited by electroplating or electroless plating, so as to form top electrode bus lines 16 made of Cu and having a thickness of, e.g., 5 im (in the figures, the lines 16 are drawn in the state that the thickness thereof is scaled down for appearance' sake).
Any one of these figures illustrates the state after the thickly plating of Cu is completed and then the plating masks (resist patterns) are removed. The resist patterns are of two kinds, one of which is a square pattern for forming an electron emission area for electron sources, and the other of which is a stripe-form pattern for dividing areas which will be the top electrode bus lines 16 and spacer lines 16 ′.
As illustrated in FIG. 15 (a plan view), FIG. 16 (a sectional view taken on line A-A′), and FIG. 17 (a sectional view taken on line B-B′), Cu in the entire surface is etched to work the thin upper contact electrode layer 15 B into a stripe form in the direction perpendicular to the bottom electrodes 11 . Since the upper contact electrode layer 15 B is far thinner than the top electrode bus lines 16 , only the upper contact electrode layer 15 B can be selectively removed by controlling the time for the etching. As the etchant, for example, an aqueous mixed solution of phosphoric acid, acetic acid and nitric acid (PAN) is suitable.
Subsequently, a resist pattern in the form of a square frame is formed on the lower contact electrode layer 15 A for forming the electron emission area (square concave portion) for electron sources. The lower contact electrode layer 15 A (Cr) naked inside the frame-form pattern is selectively worked by wet etching, so as to be removed. For the wet etching of Cr, an aqueous solution of cerium diammonium nitrate is suitable. Attention should be paid to the matter that the frame-form resist pattern is formed to cover the peripheral end of the lower contact electrode layer 15 A, as described above. In this way, top electrodes 13 , which will be formed later, will overlap with the lower contact electrode layer 15 A without breaking off so as to be connected to the layer 15 A.
As illustrated in FIG. 18 (a plan view), FIG. 19 (a sectional view taken on line A-A′), and FIG. 20 (a sectional view taken on line B-B′), a hole is made in a part of the interlayer insulator 14 by photolithography and dry etching in order to open the electron emission area in the concave portion which will make the electron emission area for electron sources. In this way, a tunneling insulator 12 is made naked. For the etching gas, a mixed gas of CF 4 and O 2 is suitable. The naked tunneling insulator 12 is again subjected to anodic oxidation to repair work-damage based on the etching.
As illustrated in FIG. 21 (a plan view), FIG. 22 (a sectional view taken on line A-A′), and FIG. 23 (a sectional view taken on line B-B′), top electrodes 13 are formed to complete an electron source substrate (finished cathode substrate 10 ). The formation of the film for the top electrodes 13 is performed by sputtering using a shadow mask. In this way, the top electrode bus lines 16 are separated from each other.
As the material for the top electrodes 13 , the above-mentioned laminated films of Ir, Pt and Au are used. The film thickness of each of the films is set to several nanometers. This makes it possible to avoid damage to the top electrodes or the tunneling insulator, associated with the photolithography and etching.
The following will describe a process for producing the whole of a display device, using the MIM type electron source substrate (finished cathode substrate 10 ).
First, a cathode substrate wherein plural MIM type electron sources are arranged on the cathode substrate 10 is formed in accordance with the above-mentioned production process.
To simplify the description hereinafter, a plan view and sectional views of the cathode substrate 10 which is a 3×4 dot MIM type electron source substrate are shown in FIG. 24 (a plan view), FIG. 25 (a sectional view taken on line A-A′), and FIG. 26 (a sectional view taken on line B-B′). Actually, an MIM type electron source matrix wherein the number of MIM type electron sources corresponds to the number of display dots should be formed.
In the case that a display device is constructed, electrode ends of the bottom electrodes 11 and the top electrode bus lines 16 must be made naked in order to connect the ends to driver circuits although this matter has not been referred to, in the description on the process for producing the MIM type electron source, hereinbefore.
(2) Formation of an Anode Substrate 110 :
Referring to FIG. 27 (a plan view), FIG. 28 (a sectional view taken on line A-A′), and FIG. 29 (a sectional view taken on line B-B′), a process for producing an anode substrate 110 will be described.
As the anode substrate 110 , light-transmitting glass is used. First, a black matrix 117 is formed in order to raise the contrast of the display device to be produced. The black matrix 117 is formed by applying a solution wherein polyvinyl alcohol (PVA) and ammonium chromate are mixed to the anode substrate 110 , irradiating the portion other than the portion where the black matrix 117 is to be formed with ultra-violet rays so as to be sensitized, removing the non-sensitized portion, applying a solution where graphite powder is dissolved thereto, and then lifting off PVA.
Next, a red phosphor 111 is formed. An aqueous solution wherein phosphor particles are mixed with PVA and ammonium chromate is applied onto the anode substrate 110 , and then the portion where the phosphor is to be formed is irradiated with ultra-violet rays so as to be sensitized, and then the non-sensitized portion is removed with flowing water. In this way, the red phosphor 111 is patterned.
The pattern is made into a dot-form pattern as illustrated in FIGS. 27 , 28 and 29 . In the same way, a green phosphor 112 and a blue phosphor 113 are formed. About the phosphors, it is advisable to use Y 2 O 2 S:Eu (P22-R) for the red, ZnS:Cu or Al (P22-G) for the green, and ZnS:Ag (P22-B) for the blue.
Next, the resultant is filmed with a film made of nitrocellulose or the like, and subsequently Al is vapor-deposited on the anode substrate 110 so as to have a thickness of about 75 nm, thereby forming a metal back 114 . This metal back 114 functions as an accelerating electrode. Thereafter, the anode substrate 110 is heated to about 400° C. in the atmosphere to heat-decompose organic substances, such as the filming film or PVA. In this way, a finished anode substrate 110 is yielded.
(3) Formation of a Display Panel:
The finished anode substrate 110 and the finished cathode substrate 10 , formed as described above, are adhered to a surrounding glass frame 116 through spacers 30 with frit glass 115 .
FIG. 30 illustrates a section of a display panel 120 obtained by the adhesion, this section corresponding to the section taken on line A-A′, and FIG. 31 illustrates a section of the display panel 120 , this section corresponding to the section taken on line B-B′. The section taken on line A-A′ and the section taken on line B-B′ of the display panel correspond to line A-A′ and line B-B′ in cases where the cathode substrate 10 and the anode substrate 110 are drawn, respectively.
The height of the spacers 30 is set in such a manner that the distance between the anode substrate 110 and the cathode substrate 10 will be from about 1 to 3 mm. The spacers 30 are made of glass or ceramic in the form of a plate. Electrical conductivity is given at least to the surface of the glass or ceramic. One-side ends of the spacer 30 are arranged on the spacer lines 16 ′ adjacent to the top electrode bus lines 16 , and they are electrically connected to each other.
The other-side ends of the spacers 30 are arranged beneath the black matrix 117 on the display substrate side (the side of the anode substrate 110 ), and are fixed with an adhesive material such as conductive frit glass 115 ′. Therefore, the spacers 30 do not hinder light emission from the phosphors. Electrical connection between each of the spacer 30 and the corresponding spacer line 16 ′ is attained by inserting the spacer 30 between the cathode substrate 10 and the anode substrate 110 under pressure and then bringing one end thereof into contact with the spacer line 16 ′, or may be attained by a conductive paste if necessary.
In the case that the spacers 30 are members obtained by coating an insulator such as glass or ceramic with a conductive material having electron conductivity as described above so as to set the sheet resistance to 1E+10 to 1E+13 Ω/square, or are conductive glass or ceramic obtained by giving electrical conductivity to such an insulator itself, the spacers 30 are preferably spacers having electron conductivity and a volume resistance of, e.g., 1E+8 to 1E+11 Ω·cm.
As illustrated in FIG. 31 , in this example, the spacers 30 are caused to stand on the respective phosphor dots which emit red (R), green (G) and blue (B) , that is, all of the spacer lines 16 ′. However, in actual display panels, the number (density) of the spacers 30 may be decreased within such a scope that necessary mechanical strength can be obtained. Roughly, the spacers 30 may be caused to stand at intervals of several centimeters.
Instead of the plate-form spacers 30 , pillar type spacers or cross type spacers may be used in other examples. In such a case, a panel can be fabricated in the same or similar way.
The panel 120 the peripheral edge portion of which is sealed is degassed into a vacuum of 10 −7 Torr in pressure so as to be sufficiently sealed up. After the sealing, a getter inside the panel is activated and the inside of the panel is kept in a high vacuum. For example, in the case of a getter material made mainly of Ba, a getter film can be formed by high frequency heating or the like. A non-evaporating type getter made mainly of Zr may be used. In this way, the finished display panel 120 using the MIM type electron sources is yielded.
As described above, in the present example, the distance between the anode substrate 110 and the cathode substrate 10 is as long as about 1 to 3 mm. Accordingly, the acceleration voltage applied to the metal back 114 can be made as high as 1 to 10 kV, thereby making it possible to use, as the phosphors, phosphors for a cathode ray tube.
FIG. 32 is a connection diagram wherein the display device panel 120 produced as described above is connected to driver circuits, and illustrates an outline of the whole of an electric circuit for driving the display device of the present example.
The bottom electrodes 11 set on the cathode substrate 10 are connected to a data line driver circuit 40 with an FPC 70 , and the top electrode bus lines 16 are connected to a scan line driver circuit 50 with the FPC 70 . In the data line driver circuit 40 , data driver circuits D corresponding to the respective data lines 11 are arranged. In the scan line driver circuit 50 , scan driver circuits S corresponding to the respective scan lines 16 are arranged.
The spacer lines 16 ′ are connected to the scan data driver circuit 50 through the FPC 70 , and ground voltage is given thereto inside the driver circuit.
An excellent point of this manner is that ground voltage is given to the spacers 30 through the spacer lines 16 ′ at the same time of the connection of the scan lines 16 .
The pixel positioned at the intersection point of the m th top electrode bus line (scan line) 16 and the n th bottom electrode (data line) 11 is represented by the coordinate (m, n). A high voltage of about 1 to 10 kV is applied to the metal back 114 from the high-voltage generating circuit 60 .
As illustrated in FIG. 32 , in the present example, it is supposed that the scan lines 16 and the data lines 11 are driven from one side of the cathode substrate 10 . However, to arrange driver circuits on both sides thereof as the need arises does not prohibit the present invention from being realized.
FIG. 33 illustrates an example of generated voltage waveforms in the respective driver circuits.
At time t 0 , voltages at all of the electrodes are zero; therefore, no electrons are emitted so that the phosphors do not emit any light.
At time t 1 , voltage V 1 is applied to only S 1 out of the top electrode bus lines 16 , and voltage −V is applied to D 2 and D 3 out of the bottom electrode lines 11 . In the coordinates ( 1 , 2 ) and ( 1 , 3 ) voltage (V 1 +V 2 ) is applied between the bottom electrode 11 and the top electrode bus line 16 . For this reason, when voltage (V 1 +V 2 ) is set to a value not less than electron emitting start voltage, electrons are emitted from these MIM type electron sources to vacuum. The emitted electrons are accelerated by the high voltage applied to the metal back 114 from the high-voltage generating circuit 60 , and then radiated into the phosphors, so that light is emitted.
In the case that voltage V 1 is applied to S 2 out of the top electrode bus lines 16 and voltage −V 2 is applied to D 3 out of the bottom electrodes 11 similarly at time t 2 , the coordinate ( 2 , 3 ) is switched on in the same manner so as to emit electrons. As a result, the phosphor on this electron source coordinate emits light.
As described above, desired images or data can be displayed by changing scan signals applied to the top electrode bus lines 16 . Images having a gray scale can be displayed by changing the value of voltage −V 2 applied to the bottom electrodes 11 appropriately.
At time t 5 , a reverse bias is applied in order to release charges accumulating in the tunneling insulator 12 . In other words, voltage −V 3 is applied to all of the top electrode bus lines 16 and simultaneously 0 V is applied to all of the bottom electrodes 11 .
In the present example, the voltage at the scan lines which are not selected is set to 0 V (ground voltage). However, as described in Patent Document 3 (Japanese Patent Application laid-Open No. 2001-83907), the use of the manner of cutting down reactive current, which follows charge-discharge, by keeping the non-selected scan lines in a high impedance state does not prohibit the present invention from being realized.
Example 2
This example discloses a manner that ground voltage is applied to the spacer lines 16 ′ without being passed through the scan line driver circuit 50 . First, according to Example 1, the cathode substrate 10 comprising MIM electron sources, the anode substrate 110 and the panel 120 are formed.
FIG. 34 is a connection diagram illustrating the display device panel 120 , which is formed as described above, connected to driver circuits. The bottom electrodes 11 are connected to the data line driver circuit 40 through the FPC 70 , and the top electrode bus lines 16 are connected to the scan line driver circuit 50 through the FPC 70 .
In the same way, the spacer lines 16 ′ are connected to the scan line driver circuit 50 through the FPC 70 . The FPC 70 used herein is made up to a circuit having internal lines for short-circuiting all of the spacer lines 16 ′ in advance. In a terminal portion of the FPC 70 , the unified spacer lines are connected to a ground line independently of the scan line driver circuit 50 .
An excellent point of this manner is that even if arc discharge is generated inside the panel 120 to apply a high voltage to the spacer lines 16 ′, the effect thereof is not produced on the scan line driver circuit 50 .
Example 3
This example discloses another manner that ground voltage is applied to the spacer lines 16 ′ without being passed through the scan line driver circuit 50 . First, according to Example 1, the cathode substrate 10 comprising MIM electron sources, the anode substrate 110 and the panel 120 are formed.
In this case, attention should be paid to the matter that in the cathode substrate 10 terminals of the spacer lines 16 ′ are extended to the outside of the top electrode bus lines 16 so as to be mutually short-circuited, which is different from Example 2.
FIG. 35 is a connection diagram illustrating the display device panel, which is formed as described above, connected to driver circuits. The bottom electrodes 11 are connected to the data line driver circuit 40 through the FPC 70 , and the top electrode bus lines 16 are connected to the scan line driver circuit 50 through the FPC 70 . The spacer lines 16 ′ are unified at one end of the cathode substrate and on the cathode substrate, so as to be connected to independent ground lines.
An excellent point of this manner is that ground lines having a low impedance can be introduced without limitation based on the performance of the FPC 70 . Consequently, even if arc discharge is generated inside the panel to apply a high voltage to the spacer lines 16 ′, damage to the scan line driver circuit 50 can be completely avoided.
Example 4
An example according to the second aspect of the present invention will be described with reference to FIGS. 17 to 45 .
(1) Formation of a Cathode Substrate 10 :
This item describes a production process in a case in which top electrodes 13 are connected electrically to an underlying layer 15 A and further top electrode bus lines 16 are backed with aluminum, aluminum alloy, or a metal having a lower resistivity than aluminum.
It is beforehand stated that the MIM electron source producing process which can be used in the present invention is not limited to the present example. The present invention can easily be applied to MIM electron sources disclosed in Patent Documents 1 and 2 (Japanese Patent Application Laid-Open Nos. 2001-101965 and 2000-208076), which comprise top electrode bus lines having a tapered structure, and other MIM electron sources.
Electron sources are produced in accordance with the manner described in Example 1, as shown in FIGS. 3 to 8 . The finished electron sources are illustrated in FIG. 36 (a plan view), FIG. 37 (a sectional view taken on line A-A′), and FIG. 38 (a sectional view taken on line B-B′). The electrical lines 16 and 16 ′ positioned, as the upper layer, inside each of sub-pixels in Example 1 and illustrated in FIGS. 21 , 22 and 23 are converted to one scan line 16 in this example and the width thereof is made two times wider so as to make the impedance thereof lower. In short, this example is characterized in that the spacer lines 16 ′ and the scan lines 16 are made common. Consequently, the step of forming the top electrodes 16 is also made simpler than that in Example 1.
The reason why some parts of the scan lines 16 can be used both as the spacer lines 16 ′ and scan lines without dividing the top electrode bus lines into the scan lines 16 and the spacer lines 16 ′ by etching will be briefly described hereinafter.
The voltage applied to the scan lines 16 is usually as low as about 5 V, but the voltage applied to the metal back 14 of the finished anode substrate 110 (i.e., the acceleration voltage) is as high as 1 to 10 kV as described above. From this fact, the voltage applied to the scan lines 16 can be substantially regarded as ground voltage, as compared with the high voltage (acceleration voltage) applied to the metal back 114 . In short, the scan lines can be regarded as spacer ground lines. Consequently, some parts of the scan lines 16 can be used both as the spacer lines 16 ′ and scan lines without making the spacer lines independent.
The finished cathode substrate 10 wherein electron sources are arranged is schematically illustrated in FIG. 39 (a plan view), FIG. 40 (a sectional view taken on line A-A′), and FIG. 41 (a sectional view taken on line B-B′). To simplify the description hereinafter, the finished substrate 10 which is a 3×4 dot MIM type electron source substrate is illustrated. In any actual display panel, an MIM type electron source matrix wherein the number of MIM type electron sources corresponds to the number of display dots should be formed.
In the case that a display device is constructed, electrode ends of the bottom electrodes 11 and the top electrode bus lines 16 must be made naked in order to connect the ends to driver circuits although this matter has not been referred to, in the description on the process for producing the MIM type electron source, hereinbefore.
(2) Formation of the Anode Substrate 110 :
The anode substrate 110 wherein a phosphor surface is formed is formed in the manner as disclosed in Example 1.
(3) Formation of a Display Panel:
Sections of the display panel 120 in the state that the finished anode substrate 110 and the above-mentioned cathode substrate 10 are adhered to each other are illustrated in FIG. 42 (a sectional view taken on line A-A′) and 43 (a sectional view taken on line B-B′). These sectional views taken on line A-A′ and line B—B correspond to line A-A′ and line B-B′ in cases where the cathode substrate 10 and the anode substrate 110 are drawn, respectively.
The spacers 30 are connected to some parts of the upper portions of the scan lines 16 (so as to avoid the electron emission area).
FIG. 44 schematically illustrates the state that this display panel 120 is connected to driver circuits. As described above, the lower ends of the spacers 30 are connected to the scan lines 16 , and the scan lines 16 are connected to the scan line driver circuit 50 through the FPC 70 .
FIG. 45 shows driving voltage waveforms when the display panel 120 produced in the present example is connected to the driver circuits as illustrated in FIG. 44 and driven. Basically, this figure is the same as FIG. 33 illustrating Example 1. In the present example, however, there are no independent spacer lines 16 ′, and at the time of selecting a given scan line out of the scan lines 16 (selecting the electron source at a given coordinate), scan line voltage V 1 is applied through the scan line beneath the lower end of the spacer. This point is different form Example 1.
Needless to say, when the electron source at a given coordinate is selected by selecting a given line out of the scan lines, electrons are emitted from the electron emission area of this selected electron source.
As a result, the spacers adjacent to the electron source are charged up. Thus, in the present example, the voltage of the spacers 30 is fixed to a lower voltage (scan line voltage) than the anode voltage (the acceleration voltage applied to the metal back 114 of the anode substrate 110 ) at the least in the period when the electrons are emitted, whereby the electrification of the spacers can be removed by the surface conduction of the spacers. It is important for suppressing distortion of the orbit of the electrons or creeping discharge to prevent the electrification of the spacers 30 .
In the case of the present example, the scan line voltage is as low as about 5 V while the anode voltage is as high as about 1 to 10 kV. Therefore, the voltage of the spacer 30 connected to this scan line substantially becomes ground voltage, so that the electrification can be sufficiently prevented.
When this scan line is not selected, reactive current following charge-discharge can be cut off by keeping the scan line, the voltage of which is usually fixed to 0 V, in a high impedance state, as described in Patent Document 3 (Japanese Patent Application Laid-Open No. 2001-83907). The use of this manner does not prohibit the present invention from being realized.
As described above, the desired objects can be attained by the present invention. In other words, in the step of producing a cathode substrate having two-layer lines, the second lines are caused to function both as scan lines and spacer (ground) lines, whereby ground lines for the spacers can be set up without increasing the number of lines. As a result, the production process can be shortened and a high yield can be attained so that costs can be reduced.
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In a cathode substrate of an FED, spacers lines exclusive for connecting spacers to the ground were necessary besides scan lines and data lines, and a cathode substrate having a three-layer line structure was used in the prior art. The present invention realizes a high-reliable cold cathode type flat panel display which is easily produced and keeps performance that can be obtained by the three-layer line structure, using a cathode substrate having a two-layer line structure.
The line structure of a cathode substrate ( 10 ) of an FED is made into a two-layer structure. Hitherto, lines of the first layer are bottom electrodes ( 11 ) which constitute electron sources and have been used as scan lines, and top electrodes ( 13 ) of the second layer have been used as data lines. In the present invention, however, the bottom electrodes ( 11 ) and the top electrodes ( 13 ) are changed to data lines and scan lines, respectively. Moreover, some parts of top electrode bus lines connected to the top electrodes ( 13 ) are used as spacer lines, too, or the top electrode bus lines ( 16 ) are divided so as to be made into spacer lines ( 16 ′).
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a roller feeder and more particularly, to a roller parallelism adjustment structure, which enables the user to adjust the transfer roller and impression roller of the roller feeder to a parallel status for accurate transfer of materials.
[0003] 2. Description of the Related Art
[0004] Following fast development of technology, people require more than the old concept of “workable” when buying or using a device. To survive in market competition, manufacturers shall have to provide products with less manufacturing cost having added values.
[0005] Taiwan Patent Publication No. 529540 discloses a roller feeder entitled “Improved Structure of Roller Feeder”. According to this design, the roller feeder comprises a machine base 1 , a transfer roller 2 , an adjustment block 3 , an impression roller 4 , a release mechanism 5 , and a digital-control power unit 6 . The transfer roller 2 is pivotally mounted in the bottom side of the machine base 1 . The impression roller 4 is pivotally mounted in the adjustment block 3 and rotatable by the transfer roller 2 . The adjustment block 3 has an eccentric shaft 31 pivotally mounted between the two sidewalls 11 of the machine base 1 . A hand wheel 32 is fastened to one end of the eccentric shaft 31 . The user can rotate the hand wheel 32 to adjust the position of the adjustment block 3 , so as to further adjust the pitch between the impression roller 4 and the transfer roller 2 subject to the thickness of the material E. During operation of the roller feeder, the digital-control power unit 6 is controlled to drive a transmission belt 63 to rotate the transfer roller 2 and the impression roller 4 , so as to transfer the fed material. The transfer roller 2 and the impression roller 4 must be kept in parallel so that fed material can be accurately transferred to the processing machine for further processing. However, due to installation error or processing error (processing precision problem) of the transfer roller and the impression roller, the transfer roller and the impression roller may be not maintained in parallel perfectly, thereby resulting in a material transferring problem
SUMMARY OF THE INVENTION
[0006] The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a roller parallelism adjustment structure, which enables the user to adjust the transfer roller and impression roller of the roller feeder to the perfect parallelism if the transfer roller and the impression roller are not kept in parallel after installation due to installation error or processing error (processing precision problem) of the transfer roller and the impression roller. To achieve this and other objects of the present invention, the roller parallelism adjustment structure comprises a roller feeder and a roller parallelism adjustment mechanism. The a roller feeder has a first end, a second end, and two rollers, namely, the transfer roller and the impression roller pivotally provided between the first end and the second end for transferring a material from the first end to the second end. The roller parallelism adjustment mechanism is installed in one side of the roller feeder to support one end of the impression roller and adjustable relative to the roller feeder to keep the impression roller in parallel to the transfer roller for accurate transfer of the fed material from the first end to the second end. In an alternate form of the present invention, the roller parallelism adjustment mechanism is installed in one side of the roller feeder to support one end of the transfer roller and adjustable relative to the roller feeder to keep the transfer roller in parallel to the impression roller.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective assembly view of a roller feeder according to a first embodiment of the present invention.
[0008] FIG. 2 is a sectional view taken along line 2 - 2 of FIG. 1 , showing the movable side plates moved and the pitch between the transfer roller and the impression roller adjusted upon feeding of material in between the transfer roller and the impression roller.
[0009] FIG. 3 is a perspective view of a part of the first embodiment of the present invention, showing the roller parallelism adjustment mechanism installed in one movable side plate according to the present invention.
[0010] FIG. 4 is an exploded view of FIG. 1 .
[0011] FIG. 5 is an exploded view of FIG. 3 .
[0012] FIG. 6 is a schematic drawing showing the impression cylinder slopped downwardly in direction from the left side toward the right side relative to the transfer roller according to the present invention.
[0013] FIG. 7 is schematic side view showing the base block of the roller parallelism adjustment mechanism deviated relative to the movable side plate and the screws deviated relative to the adjustment through holes according to the present invention.
[0014] FIG. 8 is schematic side view showing the base block of the roller parallelism adjustment mechanism adjusted and the screws in axial alignment with the respective center of the adjustment through holes according to the present invention.
[0015] FIG. 9 is a schematic drawing showing the transfer roller and the impression roller kept in parallel after adjustment according to the present invention.
[0016] FIG. 10 is a schematic drawing showing the impression cylinder slopped downwardly in direction from the right side toward the left side relative to the transfer roller according to the present invention.
[0017] FIG. 11 is schematic drawing showing the transfer roller and the impression roller kept in parallel after adjustment according to the present invention.
[0018] FIG. 12 is a perspective assembly view of a roller feeder according to a second embodiment of the present invention.
[0019] FIG. 13 is an exploded view of the second embodiment of the present invention.
[0020] FIG. 14 is a schematic side view of the second embodiment of the present invention, showing the base block of the roller parallelism adjustment mechanism deviated relative to the side panel and the screws deviated relative to the adjustment through holes according to the present invention.
[0021] FIG. 15 is similar to FIG. 14 but showing the roller parallelism adjustment mechanism adjusted, the screws in axial alignment with the respective center of the adjustment through holes.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Referring to FIGS. 1 and 2 , a roller parallelism adjustment structure in accordance with the present invention is shown comprised of a roller feeder 10 and a roller parallelism adjustment mechanism 20 .
[0023] The roller feeder 10 comprises a machine base formed of two side panels 13 a top panel 14 , a front panel X and a rear panel Y, defining a first end 11 and a second end 12 . The first end 11 is for in-feed of materials. The second end 12 is for out-feed of materials. Two movable side plates 15 are respectively pivotally mounted on the side panels 13 by a pivot shaft 16 for oscillation relative to the side panels 13 . A transfer roller 17 and an impression roller 18 are provided between the movable side plates 15 . The transfer roller 17 is driven by an external rotary driving force to rotate the impression roller 18 in the reversed direction so as to transfer fed materials from the first end 11 toward the second end 12 (see the double-arrowhead sign in FIG. 2 ). The transfer roller 17 is pivotally mounted between the side panels 13 . The impression roller 18 is pivotally mounted between the movable side plates 15 . Spring members 151 are respectively coupled between the side panels 13 and the movable side plates 15 to bias the movable side plates 15 relative to the side panels 13 . When biasing the pivot shaft 16 , the impression roller 18 will be forced against the transfer roller 17 . When a material is fed in between the impression roller 18 and the transfer roller 17 , the impression roller 18 will be slightly forced upwards by the fed material, and the movable side plates 15 will be biased to adjust the pitch between the transfer roller 17 and the impression roller 18 subject to the thickness of the fed material.
[0024] Referring to FIG. 3 , the roller parallelism adjustment mechanism 20 is mounted on one movable side plate 15 . The impression roller 18 has one end pivoted to one movable side plate 15 that does not carry the parallelism adjustment mechanism 20 , and the other end pivoted to the roller parallelism adjustment mechanism 20 .
[0025] Referring to FIG. 4 , the movable side plate 15 has a slot 152 for receiving one end of the impression roller 18 and the roller parallelism adjustment mechanism 20 , and a plurality of screw holes 153 around the slot 152 . The roller parallelism adjustment mechanism 20 comprises a base block 21 and a plurality of screws 22 . The base block 21 comprises a flat stop wall 212 , a bearing hole 211 cut through the flat stop wall 212 , an insertion flange 213 perpendicularly expended from the back side of the flat stop wall 212 around the bearing hole 211 , and a plurality of adjustment through holes 214 cut through the flat stop wall 212 around the bearing hole 211 outside the insertion flange 213 , The screws 22 are respectively mounted in the adjustment through holes 214 .
[0026] Referring to FIG. 5 , the insertion flange 213 is inserted into the slot 152 in the movable side plate 15 with the flat stop wall 212 stopped against the movable side plate 15 outside the slot 152 . After insertion of one end of the impression roller 18 into the bearing hole 211 of the base block 21 , screws 22 are respectively inserted through the adjustment through holes 214 and threaded into the respective screw holes 153 to affix the base block 21 to the movable side plate 15 . In order to smoothen rotation of the impression roller 18 , a bearing 154 is mounted in the bearing hole 211 of the base block 21 to support the respective end of the impression roller 18 .
[0027] Referring to FIG. 6 , in case the impression roller 18 is tilted relative to the transfer roller 17 in one direction and sloping downwards in direction from the left side toward the right side after installation due to processing error (processing precision problem) of the transfer roller 17 and the impression roller 18 , the transfer roller 17 and the impression roller 18 are not maintained in parallel at this time, and fed material will not be accurately fed to the processing machine. Referring to FIG. 7 , when the transfer roller 17 and the impression roller 18 are not maintained in parallel, the base block 21 of the parallelism adjustment mechanism 20 is deviated from the movable side plate 15 , and the screws 22 are respectively deviated from the respective center of the adjustment through holes 214 .
[0028] Referring to FIGS. 8 and 9 , at this time, the screws 22 are loosened, and then the base block 21 is moved in the slot 16 relative to the screws 22 to have the screws 22 be in axial alignment with the respective center of the adjustment through holes 214 , and then fasten tight the screws 22 again, keeping the impression roller 18 in parallel to the transfer roller 17 .
[0029] Referring to FIG. 10 , the impression roller 18 may be tilted relative to the transfer roller 17 and sloping downwards in direction from the right side toward the left side, causing a material feeding problem. At this time, the screws 22 are loosened, and then the base block 21 is moved in the slot 16 relative to the screws 22 to have the screws 22 be in axial alignment with the respective center of the adjustment through holes 214 , and then fasten tight the screws 22 again, keeping the impression roller 18 in parallel to the transfer roller 17 .
[0030] FIG. 12 shows roller parallelism adjustment structure according to the second embodiment of the present invention. This embodiment is substantially similar to the aforesaid first embodiment of the present invention with the exception that the impression roller 18 is pivotally mounted between the two movable side plates 15 , and the parallelism adjustment mechanism 20 supports one end of the transfer roller 17 . Referring to FIG. 13 , one side panel 13 of the roller feeder 10 has a slot 131 and a plurality of screw holes 132 around the slot 131 . The insertion flange 213 is inserted into the slot 131 , and the flat stop wall 212 is stopped against the side panel 13 outside the slot 131 . After insertion of one end of the transfer roller 17 into the bearing hole 211 , the screws 22 are respectively mounted in the adjustment through holes 214 and threaded into the respective screw holes 132 of the respective side panel 13 . In order to smoothen rotation of the transfer roller 17 , a bearing 154 is mounted in the bearing hole 211 of the base block 21 to support the respective end of the transfer roller 17 .
[0031] Referring to FIG. 14 , in case the transfer roller 11 is tilted relative to the impression roller 18 in one direction after installation due to processing error (processing precision problem) of the transfer roller 17 and the impression roller 18 , the transfer roller 17 and the impression roller 18 are not maintained in parallel, the base block 21 of the parallelism adjustment mechanism 20 is deviated from the respective side panel 13 , and the screws 22 are respectively deviated from the respective center of the adjustment through holes 214 . At this time, as shown in FIG. 15 , the screws 22 are loosened, and then the base block 21 is moved in the slot 131 relative to the screws 22 to have the screws 22 be in axial alignment with the respective center of the adjustment through holes 214 , and then fasten tight the screws 22 again, keeping the transfer roller 17 in parallel to the impression roller 18 .
[0032] As indicated above, the invention has the following advantages:
[0033] 1. By means of adjusting the roller parallelism adjustment mechanism, the nonparallel problem between the transfer roller and the impression roller due to processing error (processing precision problem) or installation error is eliminated, and therefore material can accurately be fed by the roller feeder to the processing machine for further processing.
[0034] 2. The roller parallelism adjustment mechanism can be selectively installed in the roller feeder between two positions to support the impression roller or the transfer roller to fit different types of roller feeders.
[0035] 3. The roller parallelism adjustment structure is practical for use in any of a variety of roller feeders as well as a three-in-one flattening roller feeder.
[0036] A prototype of roller parallelism adjustment structure has been constructed with the features of FIGS. 1 ˜ 15 . The roller parallelism adjustment structure functions smoothly to provide all of the features discussed earlier.
[0037] Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.
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Disclosed is a roller parallelism adjustment structure, which includes a roller feeder, which has a first end, a second end, and a transfer roller and an impression roller pivotally provided between the first end and the second end for transferring a material from the first end to the second end, and a roller parallelism adjustment mechanism installed in one side of the roller feeder to support one end of the impression roller and adjustable relative to the roller feeder to keep the impression roller in parallel to the transfer roller for accurate transfer of the fed material from the first end to the second end.
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BACKGROUND OF THE INVENTION
(1) Field of the Invention
The invention relates to the fabrication of integrated circuit devices, and more particularly, to a method and structure for providing ESD protection.
(2) Description of the Prior Art
One of the undesired side-effects of creating semiconductor devices is the accumulation of an electromagnetic charge, which can essentially occur at difficult to predict locations and which can randomly discharge. This random electrostatic discharge (referred to as ESD) is typically uncontrolled in its origin and in its occurrence and is prone to damage one or more of the elements that are part of a semiconductor device. The most likely source of the accumulation of electrostatic voltage is the frictional rubbing together of adjacent surfaces or bodies. Another source that is prone to create ESD is lightning, which can randomly distribute electrostatic voltage throughout an affected semiconductor device, thus damaging for instance thin layers of dielectric or causing junction breakdown in for instance Field Effect Transistors (FET). With increased device miniaturization it is reasonable to expect that ever smaller device features are becoming even more prone to device damage caused by ESD since ESD will have a relatively larger effect on smaller and thinner device features.
High-density semiconductor devices such as multi-chip modules and other electronic devices are typically created using unpackaged semiconductor devices. The functions of electrically contacting devices are provided by device pads on the die, which make contact with a carrier package. ESD circuits are typically provided to form an electric path from input/output pads of a die to a ground pad on the die or to a power or bias voltage path for the die. This electrical path is designed to be activated by a high voltage (such as an electrostatic discharge) that is applied to the input or output pads of the die. Most typically, ESD circuits are provided between input/output pads on an unpackaged die and the transistor gates to which the pads are electrically connected.
Conventional ESD protection circuits are frequently formed using impurity implants for the creation of the ESD device. Numerous methods are available, using N-type and P-type implants, to create ESD devices. One such method is provided by U.S. Pat. No. 5,953,601, which is for purposes of reference briefly highlighted at this time. This method is specifically provided for the technology of device feature size of 0.35 μm or less and provides for simultaneously creating FET devices and ESD protection circuits on the surface of a substrate. In forming the ESD source and drain regions, the conventional implantation species is changed from phosphorous to boron, thereby reducing the junction breakdown voltage. Ion implantation is then judiciously performed in areas that have high leakage currents and high parasitic capacitance. These ion implantations assure reduced breakdown voltages, as well as reduced leakage currents and reduced parasitic capacitances of the affected junctions. In addition, ion implantation is performed using a photoresist mask for the formation of silicidation over the contact surfaces. This avoids the problem of silicide degradation and the concomitant increase of contact resistance caused by the moving of metal ions into depletion regions of the junctions during high-energy ESD implantation.
The invention provides a method that negates the need for impurity implantation in order to create an ESD protection device. The invention teaches a special process flow and further provides for a leakage path, created by a contact etch, for the ESD protection function.
U.S. Pat. No. 5,618,740 (Huang) shows a CMOS with enhanced ESD resistance having a contact etch process.
U.S. Pat. No. 6,258,672 (Shih et al.) shows a method for an ESD device.
U.S. Pat. No. 5,891,792 (Shih et al.) and U.S. Pat. No. 5,953,601 (Shiue et al.) reveals other ESD processes.
SUMMARY OF THE INVENTION
A principle objective of the invention is to provide an ESD protection circuit that is simple and cost-effective to create.
Another objective of the invention is to provide an ESD protection circuit that is created without the need for special impurity implantations.
Yet another objective of the invention is to provide an ESD protection circuit that uses a leakage path, created using a contact etch, for the ESD protection function.
In accordance with the objectives of the invention a new process is provided for the creation of an ESD protection circuit. The invention starts with a semiconductor substrate in or on the surface of which have been created a first conventional gate electrode and a second gate electrode that is designated as being the gate electrode that provides the ESD protection function. Source/drain implants have been provided for the gate electrodes, gate spacers have been formed on sidewalls of the gate electrodes, the gate electrodes are electrically isolated. The contact surfaces of the first and second gate electrode are salicided, an etch stop layer is deposited which serves as an etch stop for the creation of contact openings to the contact surfaces of the second gate electrodes. The etch stop layer is removed from the surface of the source/drain regions of the second (that is the ESD) gate electrode. A layer of dielectric is deposited over the first and the second gate electrodes, contact openings are created through the layer of dielectric to the source/drain contact surfaces of the first and second gate electrodes. Significantly, an overetch into the source/drain regions of the second (the ESD) gate electrode occurs during this contact etch. The contact openings are filled with a metal, this metal forms metal plugs to the surface of the source/drain regions of the first gate electrode and into the source/drain regions of the ESD gate electrode. The contact plugs into the source/drain regions of the ESD gate electrode provide a low-resistivity leakage path from the contact plug through the source/drain regions into the substrate on the surface of which the gate electrodes have been created. This low-resistivity leakage path is the ESD protection path of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross section of a semiconductor substrate on the surface of which two gate electrodes have been formed. A first or left-most gate electrode is a conventional gate electrode, a second or right-most gate electrode is a gate electrode that has been designated as being the gate electrode that is to provide a ESD protection function.
FIG. 2 shows a cross section after the contact regions of the gate electrode have been salicided.
FIG. 3 shows a cross section after an etch stop layer has been deposited over the structure.
FIG. 4 shows a cross section after the etch stop layer has been removed from above the source/drain surface regions of the ESD gate electrode.
FIG. 5 shows a cross section after a layer of dielectric has been deposited over the structure.
FIG. 6 shows a cross section after contact openings to the source/drain regions of the gate electrodes have been created through the layer of dielectric, further resulting in an overetch into the source/drain regions of the ESD gate electrode.
FIG. 7 shows a cross section after the contact openings have been filled with a conductive material.
FIG. 8 shows a cross section of one of the contact plugs to the source/drain regions of the ESD gate electrode, highlighting the low-resistivity leakage path that is provided through this contact plug. The leakage path provides the ESD protection function.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Using typical ESD protection circuits, these circuits can functionally be divided into ESD detection circuits and ESD clamp circuits. The input pad to the ESD protection circuits can be connected to the IC and to the ESD protection circuit. At the time that the ESD disturbance occurs on the input pad, the ESD clamp device is forced into avalanche breakdown causing the ESD clamp circuits to conduct heavily thereby dissipating the electrostatic charge of the ESD source.
The ESD clamp circuit can be a gate grounded NMOS device having its source and bulk connected to the substrate biasing source (VSS), which may be an independent negative voltage or a ground reference point. The drain of the NMOS device is connected to the input pad of the ESD protection circuit. With this kind of a device arrangement, the NMOS device must be created with relatively large device dimensions in order to be able to effectively handle the ESD overcharge without incurring device damage. Such a device is therefore typically created using multiple fingered polysilicon gates. However, despite this robust design the NMOS device can typically sustain only a relatively low ESD voltage. This is caused by the fact that multiple heavily doped polysilicon gates cannot uniformly turn-on so that the gates that achieve earliest turn-on carry most of the avalanche discharge current and are prone to device damage (the current density in the devices that are turned-on is excessive). To achieve uniform gate turn-on, gate driven ESD clamp circuits have been designed. These circuits improve the tolerance of the MOS device to the extreme voltage levels that can occur on ESD sources. For a gate driven ESD clamp circuit, this circuit is used in conjunction with an ESD detection circuit. In the presence of an ESD condition, the ESD detection circuit is uniformly turned on. The ESD detection circuit can be as simple an arrangement as an RC combination with the capacitor connected between the input pad of the ESD protection circuit and the gate of the ESD clamp circuit while the resistor is connected between the gate of the ESD clamp circuit and ground or a low voltage reference. The voltage that is induced by the ESD disturbance at the juncture of the capacitor and resistor, a voltage that is coupled to the gate of the ESD clamp circuit, turns-on the ESD clamp circuit while this voltage can remain at a certain level for a longer period of time due to the RC constant of the components that shape this voltage.
The MOS device that is applied in the ESD clamp circuit can be a NMOS or a PMOS, the circuit configuration for an NMOS device has been indicated above. If a PMOS device is used, the ESD detection circuit is essentially the same as that used for a NMOS ESD clamp circuit. Using a PMOS device for the ESD clamp, the bulk and the drain of the PMOS device are connected to the high voltage (which is also the potential source of an ESD disturbance) while the source is connected to the low or reference voltage (possibly ground). Combined circuit arrangements have been used whereby both a NMOS and a PMOS device are used and connected as previously indicated.
It will be noted in the following description of the invention, that the ESD protection method that is provided by the invention is considerably more simple and therefore considerably more cost effective than conventional methods of providing ESD protection capabilities. The invention provides a low-resistivity leakage path through which accumulated ESD voltage can be conducted to the substrate of the device.
Referring now to the cross section of FIG. 1 , there are shown partially completed gate electrodes, the elements that are highlighted in FIG. 1 are the following:
10 , the surface of a semiconductor substrate in or on the surface of which the ESD function of the invention is to be created
12 , a conventional gate electrode that is shown as a comparative structure to the structure that provides the ESD protection function
14 , a gate electrode that provides the ESD protection function
11 , 13 , 15 and 17 , respectively the source and drain regions of respectively the gate electrodes 12 and 14
16 , the isolation region in the surface of substrate 10 that electrically separates the gate electrode 12 from the gate electrode 14
18 , the body of the gate electrode 12
20 , the body of the gate electrode 14
22 , gate spacers that have been formed over the sidewalls of gate electrodes 12 and 14 .
All of the above highlighted elements are conventional elements that are well known in the art of creating MOSFET gate electrodes. Since none of these elements that are shown in cross section in FIG. 1 are of a special nature, the enumeration of the materials used and the processing conditions applied for the creation of these elements does not contribute to an explanation of the invention and will for this reason not be performed as part of the explanation of the invention.
The cross section that is shown in FIG. 2 shows the results of creating a low-resistivity contact surface over the contact regions of the gate electrodes 12 and 14 . The contact regions are the surface of the source/drain regions of the gate electrodes and the surface of the body of the gate electrode. Two of these salicided regions are highlighted as regions 21 and 23 , 21 referring to the salicided surface 24 of the source region 11 of gate electrode 12 , 23 referring to the salicided surface 28 of the body 18 of gate electrode 12 . Further highlighted in the cross section of FIG. 2 are the salicided surface regions 24 , of the drain region 13 of gate electrode 12 , 26 , of the source/drain regions 15 / 17 of gate electrode 14 and 30 , of the body of the gate electrode 14 .
The process of salicidation is frequently applied in the art and is well known. The preferred method of the invention is to form cobalt based layers of salicided metal over the contact regions of the gate electrodes 12 and 14 .
Proceeding with the cross section that is shown in FIG. 3 , this cross section shows the results of the deposition of an etch stop layer 32 over the surface of the structure. That is the exposed surfaces of the gate electrodes 12 and 14 and the exposed surface of the substrate 10 , including the exposed surface of salicided regions 24 and 26 . The deposition of etch stop layer 32 is, for purposes of clarity, highlighted adjacent to electrode 12 as deposition 31 .
The preferred material of the invention for the creation of etch stop layer 32 is Silicon Oxynitride (SiON). Layer 32 of SiON typically has as formula SiO x N y (H z ). Silicon Oxynitrides are formed by creating SiH 4 with N 2 O and NH 3 . In order to form a non-conformal layer of SiON, a practical application uses SiO x N y deposited by PECVD with a gas flow between about 1700 and 2300 sccm of He, a gas flow of between about 80 and 120 sccm of N 2 O, a gas flow of between about 40 and 200 sccm of SiH 4 , at a temperature of between about 380 and 480 degrees C. and at a pressure between about 5 and 8 Torr. A typical carrier gas for the formation of a layer of SiO x N y is N2 or He. Layer 32 is preferably deposited to a thickness between about between about 800 and 2,000 Angstrom.
The invention continues with creating openings through the layer 32 that align with the source/drain regions 15 / 17 of gate electrode 14 . This etch has been shown in the cross section of FIG. 4 as regions 34 and 36 respectively. For this etch, conventional methods of photolithography are applied, creating a mask of photoresist that exposes the surface of salicided surface regions 24 of gate electrode 14 .
Layer 32 of SiON can be etched by exposing layer 32 to a recipe comprising O 2 , at a flow rate between 10 and 100 sccm, and N 2 , at a flow rate between 10 and 100 sccm, for a period between about 30 and 60 seconds. The preferred method of the invention for the etch of layer 32 comprises applying a dry etch or a wet etch process.
A blanket layer 38 of dielectric, preferable comprising boro-phosphate-silicate-glass (BPSG), is next deposited over the surface as shown in cross section in FIG. 5 . Re-flow is applied to the layer 38 of BPSG after deposition, BPSG flows at relatively low temperatures of between about 800 and 850 degrees C. at atmospheric pressure.
BPSG is frequently used as a dielectric material for creating an inherently planar surface. BPSG can be formed as a spin-on material that can be cured after it has been deposited on a surface. BPSG can also be formed within a Chemical Vapor Deposition (CVD) chamber, often used with a plasma enhanced or plasma assisted environment. By heating the deposited BPSG (after it has been deposited) to a temperature of about 800 to 850 degrees C., the BPSG can be made to reflow thereby creating a surface of good planarity. A time difference or lag, in the order of several (that is two) hours or more, may be required between the deposition of the layer of BPSG and the re-flow of the deposited BPSG.
The flow of BPSG depends on film composition, flow temperatures, flow time and the flow ambient environment. The film composition can be altered by increasing for instance the boron concentration of 1 wt % in BPSG, this decreases the BPSG flow temperature by 40 degrees C. However, by increasing the phosphorous content by about 5 wt % in the BPSG, no decrease in flow temperature is achieved. By further increasing the boron concentration of the BPSG film, this film becomes unstable and hydroscopic resulting in the requirement that the BPSG must be flowed immediately after it has been deposited.
BPSG further has the desirable property of acting as an alkali ion getter and of forming a low stress surface. Care must be taken that the doping limit of BPSG does not exceed certain limits since BPSG can in that case become the source of unwanted diffusion to the underlying silicon. It has been found that BPSG is primarily a source of phosphorous and that the phosphorous out-diffusion increases with increased level of boron.
BPSG is further used for sidewall contouring of contact holes by reflow. In addition to assuring that the contact holes are opened and that silicon-surface damage and contamination are minimized, it is also important to give the contact holes a shape that will result in good step coverage by the metal that is deposited into it. In general, better step coverage will be obtained if the walls of the openings are sloped and the top corners are rounded.
The layer 38 of BPSG is, after deposition and re-flow, preferably polished applying methods of Chemical Mechanical Polishing (CMP) for improved planarity of the surface of layer 38 .
The invention continues, FIG. 6 , with etching contact holes to the source/drain surface regions of gate electrodes 12 and 14 using conventional methods of photolithography and etch. Created in this manner are openings 33 , 35 , 37 and 39 . Openings 33 and 35 expose the surfaces 24 of salicided source/drain regions 11 / 13 of gate electrode 12 . Openings 37 and 39 expose and etch through the surfaces 26 of salicided source/drain regions 15 / 17 of gate electrode 14 . By etching through the salicided surfaces 26 of the source/drain regions 15 / 17 of gate electrode 14 , the contact openings 37 and 39 create a direct access to the source/drain regions 15 / 17 of ESD gate electrode 14 .
Specially highlighted in the cross section of FIG. 6 are regions 40 and 42 where the etch that creates openings 33 , 35 , 37 and 39 through the layer 38 of BPSG has etched through salicided layer 26 of gate electrode 14 and into the source/drain regions 15 / 17 of this gate electrode 14 . It is clear that the level of the impurity implantation of the source/drain regions 15 / 17 determines the conductivity of these regions to the underlying silicon substrate 10 . This level of impurity implants therefore determines the resistivity of the conductive path that is created through the source/drain regions to the underlying substrate 10 .
For the etching of layer 38 of BPSG either CF 4 or CHF 3 or C 3 F 8 or C 2 H 6 or SF 6 or combinations thereof may be used at etching gasses with dilutants such as Argon or Helium, at a pressure between about 10 to 150 mTorr and a rf power between about 100 and 1500 Watts.
The cross section of FIG. 7 shows how the openings 33 , 35 , 37 and 39 have been filled with a conductive material, preferably tungsten, creating contact plugs 44 , 46 , 48 and 50 to the source/drain regions of gate electrodes 12 and 14 . The deposited layer of tungsten (not shown) is blanket deposited over the surface of layer 38 of BPSG using methods of metal deposition such as metal sputtering and the like, filling the openings created through this layer. After this layer of tungsten has been deposited, the layer is polished using methods of CMP essentially down to the surface of the layer 38 of BPSG, leaving tungsten plugs 44 , 46 , 46 and 48 in place inside openings 33 , 35 , 37 and 39 .
Specially highlighted in the cross section of FIG. 7 are areas 52 and 54 . Area 52 highlights a contact plug 44 that makes contact with the salicided surface 24 of the source region 11 of gate electrode 12 . This is a conventional method of contacting the source region of a gate electrode. Area 54 highlights a contact plug 48 that passes through the salicided surface 26 of the source region 15 of gate electrode 14 and that further penetrates into the source region 15 of gate electrode 14 . This therefore forms a low-resistivity conductive path that can be used as an ESD protective path. The same comment applies to the contact plug 50 to the drain region 17 of gate electrode 14 .
The cross section that is shown in FIG. 8 shows essentially now familiar elements of the structure in addition to the leakage current 56 that flows from conductive plug 48 / 50 through the source/drain region 15 / 17 to the underlying substrate (not shown) 10 .
The invention has provided for an efficient, controllable (by means of controlling the level of impurity implantation into the source/drain regions of the ESD gate electrode), cost-effective and manufacturable method of providing an ESD protection capability. The methods and processes that are applied by the invention for this purpose are readily available in a semiconductor manufacturing facility, making the invention easy to integrate using standard semiconductor manufacturing facilities.
Although the invention has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the spirit of the invention. It is therefore intended to include within the invention all such variations and modifications which fall within the scope of the appended claims and equivalents thereof.
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A new process is provided for the creation of an ESD protection circuit. The invention starts with a first conventional gate electrode and a second gate electrode that is designated as being the gate electrode that provides the ESD protection function. The contact surfaces of the first and second gate electrode are salicided, an etch stop layer is deposited which serves as an etch stop for the creation of contact openings to the contact surfaces of the second gate electrodes. The etch stop layer is removed from the surface of the source/drain regions of the second (that is the ESD) gate electrode. A layer of dielectric is deposited over the first and the second gate electrodes, contact openings are created through the layer of dielectric to the source/drain contact surfaces of the first and second gate electrodes. Significantly, an overetch into the source/drain regions of the second (the ESD) gate electrode occurs during this contact etch. The contact openings are filled with a metal. The contact interconnects into the source/drain regions of the ESD gate electrode provide a low-resistivity leakage path from the contact interconnect through the source/drain regions into the substrate on the surface of which the gate electrodes have been created. This low-resistivity leakage path is the ESD protection path of the invention.
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CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of copending International Application No. PCT/DE03/01062 filed Apr. 1, 2003 which designates the United States, and claims priority to German application no. 102 14 931.3 filed Apr. 4, 2002.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention relates to an injection valve.
DESCRIPTION OF THE RELATED ART
[0003] An injection valve of this kind is known from DE 198 54 508, the valve needle being designed to open outward, and the valve needle and housing having axially cooperating pressure surfaces implemented in such a way that, if the fluid pressure changes, the same axial variation in length occurs on the valve needle and on the valve housing. It is additionally possible to set the surfaces on the valve needle in such a way that the pressure of the fluid causes no force to be exerted on the return spring or valve seat, the drive chamber in which the drive unit is disposed and the fluid chamber in which the valve needle and return spring are disposed being securely sealed against one another by means of a seal ring and an outlet.
[0004] All the pressure forces are compensated in order to keep the valve needle free from pressure forces overall. For example, when fuel pressure is high, because of the pressure-loaded surface of the valve disk of an outward opening injector, a high pressure force acting in the direction of opening is exerted which is advantageously compensated by a second pressure-loaded surface which generates a counteracting pressure force of the same absolute value. With compensation of this kind, there are then no further limitations of any kind in respect of the valve disk diameter and the needle diameter.
[0005] Moreover, it is generally known that in the case of a high pressure injection valve (High Pressure Direct Injection, HPDI) for direct injection lean burn engines having a piezoelectric multilayer actuator as drive element, another operating medium in addition to the fuel is required for the hydraulic bearing in the injector, it being known that it is possible to automatically compensate all the thermal length variations as well as all the length variations caused by setting effects of the piezoelectric element or by pressure. In terms of material selection, this obviates the need for expensive alloys with low thermal expansion (e.g. Invar) and essentially means that cheaper steel with higher strength and easier machinability can be used. On the drive side, all the moving parts are held in contact with minimal force, so that no stroke losses due to gaps are produced. For an outward opening, piezoelectrically driven injector, hydraulic length compensation is implemented by an oil-filled hydraulic chamber. However, this necessitates expensive hermetic sealing of the operating medium, e.g. silicone oil, against the pressurized fuel, the seal frequently being implemented by a metal bellows.
SUMMARY OF THE INVENTION
[0006] The object of the present invention is to provide an efficient injection valve with a simple hydraulic bearing.
[0007] This object can be achieved by an injection valve for fuel comprising a valve housing in which a drive unit controls the movement of a valve needle pretensioned by a spring, a main chamber in the valve housing which is filled with fuel and in which the valve needle is disposed, and a hydraulic bearing for the drive unit, wherein the hydraulic bearing has a hydraulic chamber which is connected to the main chamber, and wherein the hydraulic chamber is filled with the fuel as operating medium of the hydraulic bearing.
[0008] The fuel can be used for cooling the drive unit. The drive unit can be disposed in the main chamber. The axially acting pressure surfaces of the valve needle can be dimensioned such that the resulting pressure forces essentially cancel each other out, causing the resulting axially acting force on the valve needle to be minimized compared to the force of the spring. A check valve can be installed in a high-pressure port of the injection valve. The valve needle can be fixed to the drive unit. The drive unit may have a hydraulic plunger which in conjunction with the inner wall section of the valve housing forms the hydraulic chamber. A height of the hydraulic chamber can be approximately 200 to 500 μm. The drive unit together with the hydraulic plunger and the valve needle may form a fixed unit which can be displaced virtually unimpeded relative to the injector housing in the event of slower movements occurring compared to the injection process, taking the spring forces into account. The drive unit can be connected to a hydraulic plunger which divides the inner chamber of the housing into the hydraulic chamber and the main chamber. The hydraulic chamber can be connected via a cross duct to a fuel supply duct entering the main chamber. Electrical leads of the drive unit can be brought out of an opening in the housing, and between the drive unit and the housing there can be provided a flexible means of sealing. The entire inner chamber of the valve housing between the means of sealing and an oppositely disposed valve seat can be filled with the fuel. The hydraulic chamber can be bilaterally delimited by narrow annular gaps opposite the inner chamber of the valve housing.
[0009] There is implemented an injector principle which obviates the need for an additional operating medium for the hydraulic bearing. The fuel fills via at least one annular gap the valve's hydraulic chamber which ensures length compensation.
[0010] The fuel-pressurized hydraulic chamber is advantageously of very rigid construction in order to be able to absorb very high compressive and tensile forces for short periods, as is required for rapid opening and closing of the valve. The injection valve can therefore close approximately 5-10 times as quickly as in the case of resetting by a return spring alone according to the prior art, while at the same time preventing the losses in the valve needle stroke caused by the disadvantageous extension of the valve needle because of a high restoring force acting through the return spring.
[0011] According to the invention, the fuel pressure induced forces acting on the valve needle can be selectively set. For example, a fuel pressure induced closing force could be set, thereby ensuring that the valve needle reliably closes the valve even if the return spring is broken.
[0012] By means of appropriate routing of the fuel ducts, the fuel flows past the drive unit and, for example, the multilayer actuator and cools the piezoceramics. A further advantage therefore consists in the improved temperature characteristics of the injector. Direct injection into the combustion chamber subjects the injector to high temperatures. Moreover, modern injection concepts provide for multiple injections. The trend is toward continuous injection rate forming. Concepts involving 5 injections per cycle are already under discussion. This would produce additional waste heat. Injector cooling is therefore advantageous, even if no temperature problem has yet arisen with injectors according to the prior art using silicone oil as operating medium for the hydraulic bearing.
[0013] Thermal expansion, aging and setting effects cause the absolute position of the piezoelectric unit as well as the position relative to the valve housing to vary. Typical values are as much as a few 10 μm, but always well below 100 μm. The hydraulic chamber must be implemented high enough to ensure that it can compensate all the variations in length to be expected during service life. On the other hand, the hydraulic chamber must be implemented with as little height as possible in order to be able to form an abutment that is as rigid as possible. A typical hydraulic chamber height of 200 to 500 μm is therefore selected.
[0014] In order to facilitate filling of the hydraulic chamber with fuel it is provided that the hydraulic chamber is connected via a cross duct to a fuel supply duct leading into the main chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] An exemplary embodiment of the injection valve according to the invention will now be described; the single FIGURE shows the injection valve in simplified form in a schematic longitudinal cross-sectional view.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] A high-pressure injector or the injection valve has a valve seat 3 in an injector housing 1 . One diameter of the sealing line d 1 is typically 3-5 mm for a fuel-injection valve. In the basic state the valve seat 3 is held closed by means of a valve disk 7 connected to the lower end section of a valve needle 5 (diameter d 2 ), said valve needle 5 being disposed in a valve housing 1 . The closed basic state of an injection nozzle 9 formed by the valve seat 3 and the valve disk 7 at the end of the housing 1 is ensured by a tensioned compression spring 11 with a typical spring force (F S ) of approximately 150 N. The compression spring is mounted between a base plate 13 of a drive unit 15 and a section of the inner wall of the valve housing 1 . The valve needle 5 is rigidly connected, e.g. welded, to the base plate 13 . The fuel is supplied to an inner chamber of the valve housing 1 through a duct bore 17 provided in the injector housing 1 . In the upper section of the injector housing 1 there is disposed the drive unit 15 . This is constituted by a piezoelectric multilayer actuator in low voltage technology (PMA) 19 , a tubular spring 21 , a hydraulic plunger 23 and the base plate 13 . The tubular spring 19 is welded to the hydraulic plunger 23 and the base plate 13 so that the multilayer actuator 19 is under mechanical pre-compression. Electrical terminals 25 of the drive unit 15 are brought out upward from the housing 1 , as described below. The inner chamber of the valve housing is separated by the hydraulic plunger 23 into a main chamber 27 , accommodating in particular the PMA 19 , and a hydraulic chamber 29 . Above the hydraulic chamber 29 , the drive unit 15 is connected to the injector housing 1 by means of a metal bellows 31 with a hydraulic or effectively pressurizing diameter d 5 , thereby closing the inner chamber of the valve housing 1 to the environment. The inner chamber is additionally connected to the duct bore 17 in the vicinity of the metal bellows 31 via a cross duct 33 .
[0017] In the basic state, with a fuel pressure p K of typically 100-300 bar applied, although very large pressure forces F D =p K ·π·(d 1 2 −d 5 2 )/4 act on the base plate 13 and the hydraulic plunger 23 , possibly producing a pressure force of F D =1000-5000 N, this is cancelled out in the pressure balance if d 1 =d 5 is selected. The pressure compensation does not need to be mathematically precise, but only accurate enough, as will now be described.
[0018] For typical injection valve dimensions, even a change in the fuel pressure from 100 to 300 bar at a 1 mm 2 deviation of the pressurized surfaces from the ideal compensation state results in an additional force (F D ) of approximately 20 N about which the closing force in the valve seat 3 varies. This force may counteract the spring force (F S ) of the compression spring 11 and, in the worst case scenario, unintentionally open the valve. On the other hand, this additional force (F D ) can also amplify the spring force (F S ) thereby making the valve more difficult to open. As the size of this unwanted additional force (F D ) increases, precise control of the injection process becomes more difficult. In particular, modern designs with multiple injection are then barely implementable any more. Preferably at least: F S >5·F D, , in particular F S >10·F D .
[0019] The hydraulic plunger 21 is fitted into the correspondingly implemented injector housing 1 by means of a first and a second tight clearance fit 35 , 37 having a larger diameter d 3 and a smaller diameter d 4 and forms with the corresponding inner wall sections of the injector housing 1 the annular hydraulic chamber 29 . When the injector is installed, the height of the hydraulic chamber h K is typically set to at least 100-500 μm. The hydraulic chamber 29 is used, for example, for compensating slow length variations (e.g. typical time durations t>1 s) of the drive unit 15 and/or of the valve needle 5 with respect to the injector housing 1 that are thermally induced or caused by aging effects of the PMA 19 in the injector. If these slow length variations occur, an unimpeded fluid exchange between the hydraulic chamber 29 and the surrounding fuel-filled inner chamber of the injector or of the main chamber 27 and the cross duct 33 can take place for length equalization via the narrow sealing gaps of the clearance fits 35 , 37 of the hydraulic plunger 23 . These slow variations are therefore compensated by a variation in the height of the hydraulic chamber 29 .
[0020] However, the sealing gaps between the hydraulic plunger 23 and the valve housing 1 must at the same time be narrow enough to ensure that, within typical injection times (0 ms<t<5 ms), no appreciable fluid exchange can occur between the hydraulic chamber 29 and the surrounding fuel-filled inner chamber of the injector, in particular the main chamber 27 . The height of the hydraulic chamber h K must be able to vary by no more than about 1-2 μm due to leakage. In order to be able to open the valve and keep it open over a period 0 ms<t<5 ms during operation and then close it again, an average force of about 100-200 N is typically required depending on the magnitude of the spring force F S . For a typical pressurizing surface A K =π·(d 3 2 −d 4 2 )/4 of approximately 240 mm 2 (assuming: d 3 =18 mm, d 4 =4 mm), the average pressure in the hydraulic chamber varies by Δp=200 N/A K <10 bar relative to the fuel pressure. The fluid flow through the maximally eccentrically disposed sealing gaps can be calculated by
Q L =2.5·π·( d 3 +d 4 ) h 3 ·Δp /(12·η·1) with:
Viscosity of gasoline: η=0.4 mPa·s;
Gap height: h=2 μm; Length of sealing surfaces: 1=10 mm Injection time: t E =5 ms we get Q L =28.8 mm 3 /s;
Δ V=Q L ·5·10 −3 s=0.144 mm 3 ;
[0024] With Δx=ΔV/A K we get Δx=0.6 μm as stroke loss because of the leakage flow during the injection time under the assumptions made above.
[0025] Because of the compressibility of gasoline, the hydraulic chamber 29 possesses a spring effect resulting in an additional loss in the valve stroke. The minimum spring rate of the hydraulic chamber 29 c K is calculated in accordance with c K =A K /(χ·h K ) with χ=10 −9 m 2 /N and h K =500 μm to give c K =500 N/μm and we therefore get:
Δ x=ΔF/c K =200 N/500 N/μm=0.4 μm as the stroke loss of the valve because of the compressibility of gasoline.
[0026] This shows that the maximum stroke loss occurring, which is caused by the hydraulic chamber 29 , is sufficiently small with suitable dimensioning. Altogether the drive unit 15 with the hydraulic plunger 23 and the valve needle 5 form a unit which can be displaced, as an entity, virtually unimpeded relative to the injector housing in the event of slow movements occurring compared to the injection process until the seating force (F D +F S ) between the valve seat 3 and the valve disk 7 is set. The length of the annular gap is relatively uncritical here, the leaking flow decreasing with increasing length. As the leakage increases as the cube of the gap height h, the gap height must be selected sufficiently small. To summarize, therefore, slow variations in length, particularly of the PMA 19 , are compensated by the hydraulic chamber 29 so that reproducible time responses of the valve needle stroke and therefore of the injection quantities can be controlled across all operating states and thermal loads. For the valve shown in the FIGURE the routing of the fuel in the injector housing is implemented in such a way that the functions of cooling the PMA 19 and of length compensation can be performed by means of the hydraulic chamber 29 using a single fluid.
[0027] The operation of the injection valve is now as follows: to start the injection process, the PMA 19 is charged via the electrical terminals 25 . Because of the inverse piezoelectric effect, the PMA 19 expands (typical deflection: 30-60 μm), the PMA being supported on the rigid hydraulic chamber 29 in order to lift the valve disk 7 from the valve seat 3 against the spring force F S of the compression spring 11 . The fuel can now emerge from the injection nozzle 9 . The valve disk 7 is now subjected to the pressure of the injection chamber (not shown) on its lower surface facing away from the fuel, the hydraulic chamber 29 being implemented, as described above, as sufficiently rigid over a typical injection duration. To terminate the injection process, the PMA 19 is discharged again via the electrical terminals 25 and the PMA contracts. The hydraulic compressive stress (=hydraulic tensile force) and the spring resetting force of the compression spring 11 draw the valve disk 7 into the valve seat 3 and therefore close the valve. In the end position with the valve closed the hydraulic chamber 29 is maintained at a minimum height, the largest contribution to the resetting force coming from the hydraulic pre-compression. Because of its high rigidity and the high fuel pressures(p K =100-300 bar), the hydraulic chamber 29 is able to absorb even high tensile forces (F Z =p K ·π·(d 3 2 −d 4 2 )/4 of F Z =1000-5000 N) without appreciable variation in the hydraulic chamber height h k .
[0028] By installing a check valve in the high-pressure port of the injector, high pressure can be maintained in the injector over a lengthy period while the fuel pump is switched off (not shown). When the engine is restarted, the injector volume itself is used as fuel pressure reservoir for the initial injection processes, until the injection pump injects the necessary fuel pressure into the injector.
[0029] Alternatively a magnetostrictive device can also be used as the drive for actuating the valve. With a suitably designed stroke reversal, the system described can also be used in principle for inward opening valves.
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An injection valve for injecting fuel comprises a valve housing ( 1 ) inside of which a drive unit ( 15 ) controls the movement of a valve needle ( 5 ) that is pretensioned by a spring ( 11 ). The injection valve also comprises a main chamber ( 27 ), which is provided inside the valve housing, is filled with fuel and accommodates the valve needle ( 5 ), and comprises a hydraulic bearing for the drive unit ( 15 ). The hydraulic bearing has a hydraulic chamber ( 29 ) that is connected to the main chamber ( 27 ), whereby fuel serves as the operating substance of the hydraulic bearing.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to telephone circuits for ring trip detection and, more particularly, to monolithically integrated telephone circuits for ring trip detection that can constitute an interface between the user's telephone line and the user's circuit line under the control of the telephone exchange control equipment.
2. Discussion of the Related Art
A user's telephone apparatus is coupled to the telephone exchange by means of a line whose terminals are coupled in parallel both to the conversation circuit and the ringing mechanism.
A switch is coupled in series with the conversation circuit which is turned off when an off-hook condition, i.e. when the receiver or headpiece is removed from the body of the telephone, takes place. A capacitor is coupled in series with the ringing mechanism to decouple the ringing mechanism from the direct current line. The direct current line is in fact powered by a direct current generator coupled in series with an alternating current generator which represents the ringing signal generator when the telephone exchange control equipment sends a call signal to the user. Therefore, when there is call, a d.c. component superimposed on a ringing alternating current appears on the line in the off-hook condition.
The ringing signal generally has a frequency of 25 or 50 Hz, with an effective voltage value rather high (60 V to 80 V) relative to the normal telephone conversation signals. If the ring signal is not immediately interrupted at the moment of the off-hook, it is converted by the conversation circuit to a high intensity acoustical signal, which can be detrimental to the hearing of the user.
When electronic circuits have been introduced for the detection of the off-hook condition directly in the user's circuits in the exchange, the problem has risen in recognizing immediately the off-hook condition from the variations of the line current by sensing a possible presence of a d.c. component on the user's telephone line in order to be able to interrupt in a timely manner the generation of the ringing signal. With this recognition, the central control equipment can interrupt the sending of call signals.
In effect, it is not easy to execute such a sensing when the a.c. current due to the ringing signal has an effective value much larger than the value of the direct current present after the off-hook condition is established. The large diversity of impedances that can exist in the various lines and the user's telephone apparatus also makes it necessary to design circuits for the ring trip detection that have sufficient sensitivity, taking into account the worst case that can be established. If the line current is only in the alternating state when the off-hook has not yet occurred in the ringing phase, the line current wave form is comprised of a succession of positive and negative parts which are symmetric in respect to the zero amplitude reference. This symmetry occurs even when the wave form is not perfectly sinusoidal as, for example, when there are non-linear components in the electric circuits coupled to the line.
Therefore, the duration time of the half-waves of current, positive and negative, are equal. The areas defined by the wave form in the positive and negative half-waves are equal.
When the off-hook condition takes place and the conversation circuit direct current is added to the alternating current of the ringing signal in the half-wave periods in which the sign of the alternate current is equal to that of the direct current, the peaks of the wave form of the line current in which the alternating current and the direct current are found to be larger than those peaks in which the alternating current and the direct current have opposite signs.
Therefore, when the off-hook condition occurs, the positive half-wave periods of the line current in the ringing phase have a different duration than that of the negative half-wave periods. The area defined by the wave form of the current in the positive half-wave periods also is found to be different from that of the negative half-wave periods. The difference in these parameters are determined by the amplitude of the direct current. Two distinct procedures are utilized in the related art for the ring trip detection. They are based on the detection of the differences between the positive half-wave and the negative half-wave of the line alternating currents as altered by any direct current component.
A first procedure based on a comparison of the duration times of the positive and negative half-wave periods for one or more periods is, for example, made by counting the number of impulses having a predetermined duration time that can occur in each half-wave periods with one of the methods known to a person skilled in the art. The control devices that actuate such procedure do not however guarantee a sure detection of the off-hook condition in all of the conditions of the telephone network that can arise in practice. In fact, in a telephone line, some stray current is always present that, added to the line alternating current, can shift the point of separation between the positive and negative half-wave periods of the current wave form or make the position of this point uncertain. In this way, an "indetermination interval" of the detection is created whose amount depends on stray current which, in turn, depends on the different lengths and impedances of the lines. Therefore, such control devices can be effectively utilized only when the conditions of the line guarantee an indetermination interval under predetermined values.
The second procedure is actuated by measuring, during one or more periods, the total area defined by the wave form, attributing a positive value to the positive peak area and a negative value to that of the negative peak area. If the value of the total area is not equal to zero and exceeds a predetermined threshold value for certain detection, this value signifies that there is a direct current component in the line alternating current, i.e. the off-hook has taken place, and a command can be given to the exchange equipment, to interrupt the sending of call signals. Such a measure, defined as a measure of an "average value", can be effected by means of an integrator circuit that generates a signal proportional to the integral of the line current for one or more full periods. The generated signal has a zero value, or a value under a predetermined threshold only when, in the ringing phase, the off-hook condition has not yet taken place.
Such an integrator, as is well known to a person skilled in the art, can be realized simply with a RC type network. When, however, monolithically integrated telephone circuits are used to actuate this second procedure, there is a problem of sensitivity of the recognition device. In fact, for the integration during one or more periods, the signal value generated by the integrator during the period can be much higher than the final value that indicates an eventual off-hook condition and, especially when the line current is not perfectly sinusoidal, and has high peaks, the signal value can not be compatible with the limited dynamics of the integrated circuits that are used. On the other hand, because the off-hook direct current has a much lower value than the ringing alternate current, the line current cannot be altered without lowering the sensitivity of detection.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a monolithically integrated telephone circuit for the ring trip detection adapted to be used as an interface between a user's telephone line and a user's circuit line under the control of the exchange control equipment.
It is a further object of the present invention to provide a circuit for ring trip detection with a high certainty of detection of the off-hook in all of the different telephone network conditions and as compared with the known circuits in a larger field of use.
The aforementioned and other objects are accomplished, according to the present invention, by a telephone circuit for the ring trip detection that includes a current transducer circuit (TR) coupled to a user's telephone line and supplying a current (I T ) proportional to the current of the line (I L ) for current values included between two predetermined threshold values, opposite in sign and equal in absolute value. When these threshold values are achieved, the current (I T ) supplied by the transducer (TR) is maintained constant as the line current (I L ) varies outside of these values. The telephone circuit for ring trip detection further includes an integrator circuit (INT) that integrates the current supplied by the transducer during one or more full periods of the alternating line voltage. When the result of such an integration is different from zero, the detection circuit can inform the telephone exchange control equipment that the off-hook condition has taken place.
These and other features of the present invention will be understood upon reading of the following description along with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block diagram of a telephone circuit for the ring trip detection according to the invention.
FIG. 2 shows the wave form of the current that is generated by a non-linear current transducer included in the detection circuit and coupled directly to the user's telephone line.
FIG. 3 illustrates a circuit diagram of a non-linear transducer circuit of the type included in a detection circuit according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
According to the present invention, a telephone circuit for the ring trip detection includes a non-linear current transducer, represented in FIG. 1 by block TR, in which the current transfer characteristic is indicated. The current transducer is coupled to a user's telephone line, not represented in the figure, and is driven by the line current, I L . According to the invention the transducer TR provides an output current, I T , proportional to the line current I L for values of the line current included between two predetermined threshold values, the threshold values being opposite in sign and equal in absolute value and denoted by +I S and -I S . Beyond the threshold values, the current I T supplied by the transducer is maintained constant and independent of variations of the line current I L . The limit values, opposite in sign and equal in absolute value, between which the current I T can linearly vary, are indicated as +I K and -I K .
A current integrator, INT, is coupled to the transducter TR. The current integrator generates a signal S having a value proportional to the value of the integral over time, starting from a predetermined instant, of the current I T supplied by the transducer TR wherein: ##EQU1##
A control circuit means, C T , connected to the integrator INT and driven by the user's line voltage, V L , determines the integration intervals by means of control pulses that bring back, at predetermined instants, the current integrator to the initial conditions.
According to the present invention, the current I T is integrated over time intervals equal to one or more full periods of the alternating line voltage, the duration time of which coincides with that of the periods of the line current. In this way, the current defined integral value is different from zero only when there is a direct current component determined by the off-hook condition of the receiver that has shut off the conversation circuit on the line.
A comparator circuit, COMP, coupled to the integrator circuit, INT, and to the control circuit means, C T , compares the signal S with a reference signal S RIF and generates, when the difference between the two signals resulting from the off-hook condition is different from zero and larger than a predetermined value, a signal S OUT . The signal S OUT informs the exchange control equipment, not represented in the diagrams, of the off-hook condition, so that the same equipment interrupts the generation of the call signals. However, the comparator is enabled from the control circuit means C T to send the signal to the exchange control equipment only when the integration of the current I T has been defined by the control circuit means C T . In fact, as has already been stated, the value of an integral over time of an alternating signal greatly varies during a period. Therefore, the integral can have intermediate values much higher than the final value, which can determine erroneously the interruption of the ringing signal.
In FIG. 2, the wave form is represented for a time interval equal to a full period, T, of the output current I T of the transducer TR when, in the ringing phase, the off-hook condition has taken place and therefore a direct current I o is also on the line. Assuming a proportionality ratio equal to one between the currents I L and I T in the linear part of the transfer characteristic of the transducer, such wave form, that is indicated in the figure with a straight line, is, between the two limit values +I K and -I K , an exact replica of that of the line current I L . In FIG. 2, a dotted line shows the peaks of the user's line current that are suitably smoothed by the transducer. The limit values +I K and -I K are determined according to the characteristics of the line and of the apparatus coupled to the line and according to the level of the direct current I o . A 1 and A 2 indicate the areas defined by the wave form of I T in the half-wave periods t 1 and t 2 . Because of the direct current I o , these areas and half-wave periods are found to be different from one another.
The signal S generated from the integrator circuit is proportional to the integral of the current I T or proportional to area along with the sign defined by its wave form. The signal S is a measure, when the integral is defined on a full period T by the control circuit means C T , of the difference between the areas A 1 and A 2 . The signal S has a value that is therefore different from zero only when the off-hook condition has taken place and the direct current I o is also on the line.
For a greater reliability, because the value of such a defined integral can, in fact, be different from zero even when the off-hook condition hasn't taken place, a detection threshold is determined by the comparator circuit that compares this value with a reference signal. Because of the non-linear transducer circuit TR, the problems that arise with monolithically integrated telephone circuits are completely eliminated. Independent of the peak values of the alternating line current I L , the maximum values of the current I T supplied by the transducer circuit are always included within exact limits defined by its transfer characteristic. However, because the characteristic of the transducer within the two threshold values is linear, the detection sensitivity for low levels of line current is not limited and, therefore, a circuit according to the present invention can be utilized in any line condition. In that situation, when the threshold values are suitably selected and the characteristics of the user's line and terminal are known, the circuit operation can be optimized.
The circuit diagram of a non-linear transducer, which could be used to practice an off-hook detection circuit in conformity with the invention, is represented in FIG. 3. This circuit includes a differential circuit comprising a first and a second PNP transistor, T 1 and T 2 , whose base terminals receive the input signals for the differential circuit. The base terminal of T 1 is the input of the transducer, to which the user's line current, I L , is applied. The base terminal of T 2 is coupled to the ground connection, whose potential is intermediate between the potentials of the positive pole, +V cc , and of the negative pole, -V cc , of a supply voltage generator to which the transducer is coupled. The emitters of transistors T 1 and T 2 are coupled to +V cc through a constant current generator I K . The collector of transistor T 1 is coupled to the base of a third transistor, T 3 , of the NPN type, and to the anode of a first diode, D 1 . The emitter of transistor T 3 and the cathode of D 1 are coupled to -V cc . The collector of transistor T 2 is coupled to the bases of a fourth and a fifth transistor, T 4 and T 5 , both of the NPN type, and to the anode of a second diode, D 2 . The emitters of transistors T 4 and T 5 and the cathode of D 2 are connected to the -V cc terminal. The collector of transistor T 3 is coupled to the cathode of a third diode, D 3 , and to the bases of a sixth and a seventh transistor, T 6 and T 7 , both of the PNP type. The anode of diode D 3 , and the emitters of transistors T 6 and T 7 are coupled to the +V cc terminal. The collector of transistor T 6 is coupled to the base of transistor T 1 and to the collector of transistor T 4 . The collectors of transistor T 5 and T 7 are coupled together to form a terminal to which the output current I T of the transducer circuit is made available. Between the base of transistor T 1 and the ground potential, two diodes, D 4 and D 5 are inserted in parallel to each other, but in opposite orientation from one another. The function of the transducer circuit, as will be clear to a person skilled in the art, is determined by the current generator I K that imposes the maximum absolute value, precisely equal to I K , of the output current I T . The implementation of the INT integrator, included in a detection circuit in accordance with the invention, can instead be effected by means of a capacitor with a capacitance C, for which a plate is coupled to the ground and the other plate is coupled to the output of the transducer TR and to an input of the comparator COMP, the latter being implemented in a known manner. The two plates can be short-circuited through a switch controlled by the control circuit means C T by means of pulses at predetermined instants, spaced by one or more full periods of the line voltage (or current). The capacitor, which is discharged every period for example, is then progressively charged, in the following period, by the transducer output current I T . Between the capacitor plates, a time varying voltage, V c , is established, wherein: ##EQU2## that can be used as signal S to be compared with a reference voltage S RIF , by means of the comparator COMP. The control circuit means C T can be implemented by one skilled in the art as a circuit that is driven by the voltage of the user's line and wherein every period results in the generation of a pulse adapted to command the switch for the capacitor discharge and to enable the comparator circuit to send a detection signal to the exchange equipment. The control circuit can, for example, comprise a circuit known by the name of "zero crossing level circuit".
Although only one embodiment of the invention has been illustrated and described, it is obvious that many modifications are possible without departing from the scope of the invention itself. For example, the signal S could be generated as a pulse only at the end of the time interval for which the integration of the current I T is performed. In this way the detection signal generated by the comparator circuit would be sent to the exchange equipment, without further commands from the control circuit C T only at the end of the integration periods. The control circuit C T could then be driven by the line current itself, instead of the line voltage V T .
The above description is included to illustrate the operation of the preferred embodiment and is not meant to limit the scope of the invention. The scope of the invention is to be limited only by the following claims. From the above description, many variations will be apparent to one skilled in the art that would yet be encompassed by the spirit and scope of the invention.
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A telephone circuit for ring trip detection that can be monolithically integrated, includes a current transducer coupled to a user's telephone line, and an integrator circuit. The output current of the current transducer is proportional to the line current until equal and opposite threshold values are reached. When the line current threshold values are exceeded, the transducer output current is constant. The transducer output current is integrated by the integrator circuit over at least one complete cycle. When a telephone headset is removed, a direct current is applied to the ringing signal current resulting in asymmetry in the half-cycles of the transducer output current. The asymmetry provides a non-zero integrated current for a complete cycle. When the integrated value of the asymmetrical current is greater than a selected value, a signal is applied to the ringing circuit, halting the ringing signal.
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This is a Continuation-in-Part of a co-pending application AIR CIRCULATION SYSTEM, having Ser. No. 07/536,179, filed Jun. 11, 1990 now U.S. Pat. No. 5,065,668.
FIELD OF THE INVENTION
The invention relates to an improved air circulation system for workspace units, and particularly to workspace units which stand alone and which have a plurality of work stations centered about a center column or core.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 4,625,633, in the name of Martin, is a commonly owned patent which describes a ventilated core unit for service connections. Various prior art patents are disclosed in the Martin patent. The disclosure of all of those prior art patents may be summarized by the statement in the Martin patent that none of the prior art disclose the benefits of an independently controllable zone unit that is not attached to the building HVAC equipment by air ducts.
Martin correctly identifies a modern trend in office furniture and layout arrangements, in which small, semiprivate working cubicles are created about a central core with multiple work stations and equipment emitting from that core. The Martin design has been very successful in providing a central core unit which accomplishes both ventilating and utility connections for peripheral work spaces.
The principal basis upon which the Martin invention is founded is the use of a central core unit for local ventilating and also for providing utility connections to peripheral work spaces around the core. The work spaces each are provided with electrical terminal devices and air inputs. A work space fan is mounted in a side wall of the cabinet. That fan is operable under user control to draw air from the work space into the plenum defined by the walls of the cabinet. The air is then discharged to the common area directly above the workspace.
No system is perfect, however, and several drawbacks have been encountered in the use of the Martin system. Specifically, the system is both assisted by and encumbered by the fact that it has a central column 30 which functions as a service conduit. This central core conduit makes it easy to supply power to the system. It also makes it significantly more difficult to remove the top 24 of the core for access to the internal mechanisms. In addition, mounting a filter 84 and fan 80 on the top 24 causes an imbalance unless the filter is centered. Of course, when a center conduit 30 is present, that cannot be accomplished. Alternatively, a plurality of fans 80 are required. In either case, difficulty in cleaning the filter 84 is significant because the center conduit is directly connected to top 24 of core unit 20.
Yet another difficulty which is experienced in prior art systems is that each core wall of core unit includes it own inlet fan which is adjustably controlled by the worker at each specific work station. This fan, however, does not directly control the exhaust air. A worker must be present in order to control the use of the specific intake fan for each wall of the core. In addition, of course, the requirement of a separate fan for each core wall increases expense and complicates the assembly and maintenance of the system.
Even though the Martin system is successful and provides many advantages to the users, that system is not capable of providing a complete, controlled environment which would be ideal under present day standards. Specifically, what is needed is a more efficient and effective way to transfer or treat the air within the region of all of the work stations about a central core workplace.
Ideally, the environment directly centered about the core of the stand alone work space should have the best possible environment. Particularly, bacteria and smoke should be eliminated and the individual work stations should each function in the nature of a cleanroom.
In addition, the device should be simple and easy to maintain. Access to the interior of the column for maintenance of other equipment should be facilitated and should not be prevented by the design of the air flow system. Greatly improved efficiencies and the ability to provide virtually an envelope of clean air are objects of the present invention and are not found in the prior art.
SUMMARY OF THE INVENTION
It has now been discovered that these and objects of the present invention are accomplished in the following manner. Specifically, an apparatus for use with multi-station work spaces has been discovered. The device includes a predetermined number of core walls which define an enclosed core. Each of the core walls include an inlet vent at or below a predetermined height.
Positioned within the core at a location above the predetermined height is a platform means. The platform substantially separates the core into a lower air intake chamber and an upper air discharge chamber. The platform further includes filter means in the lower chamber. The filter may include prefilter means which filter odor and/or large particles. Also included are air transfer means for drawing air from the intake chamber through the filter to the upper chamber.
In addition, the apparatus of the present invention includes core lid means, which is positioned at the top of the core defined by the core walls, to complete the enclosure of the air discharge chamber. The core lid includes air discharge means in the form of side vent means proximate each of the core walls for discharging air in a substantially horizontal direction out from each of the core walls to form an envelope of air with the inlet.
Typically, the predetermined height is positioned sufficiently above a normal work surface so that the vent means is positionable above the normal work surface of a work station. The platform is mounted in a position abutting all of the core walls to substantially prevent air flow between the intake chamber and the discharge chamber except through the filter means. Specific filters are preferably those filters known as HEPA filters, which have a minimum efficiency of 99.97% of particles measured at 0.3 microns.
The core lid is assembled to direct air out horizontally through side vent means which may or may not include baffles to further direct the air in a horizontal direction. Because the side vent means is exhausting a significant volume of air horizontally and above the seated worker, and because all of the air in the system is drawn in to the vent means in the core walls, a person seated at the work station is surrounded or encapsulated by an envelope of air from which most of the particles 0.3 microns and larger have been removed. This envelope of air is effective as a cleanroom.
In its preferred form, the apparatus of the present invention includes a single motor and blower mounted in the upper chamber. The blower has sufficient capacity to provide up to about 30 air changes per hour for the region included in a thirteen foot circle having its axis at the center of the core. This motor has a capacity rating of at least 300 cubic feet per minute. Other sizes and capacities are also useful.
Finally, it is also contemplated that the preferred embodiment of the present invention will include a prefilter means on the filter, which prefilter is suitable for removing odors and/or larger particulate from air passing through the filter means. Activated charcoal and polyester filters may be used for these functions.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects of the present invention and the various features and details of the operation and construction thereof are hereinafter more fully set forth with reference to the accompanying drawings, where:
FIG. 1 is a side elevational view of the device of this invention in place in a multiple work unit.
FIG. 2 is a plan view of the multiple work station shown in FIG. 1.
FIG. 3 is an enlarged section view taken along lines 3--3 of FIG. 2.
FIG. 4 is a plan view, partially cut away and partially in section, of the center portion of the device of FIG. 3.
FIG. 5 is a greatly enlarged view of the portion in the circle shown in FIG. 3 and designated FIG. 5.
FIG. 6 is a sectional view taken along the lines 6--6 of FIG. 5.
FIG. 7 is an enlarged view of the circle shown in FIG. 3 and designated FIG. 7.
FIG. 8 is an enlarged view similar to FIG. 3, showing an alternative, preferred embodiment.
FIG. 9 is a plan view, partially cut away and partially in section, of the center portion of the device of FIG. 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A workstation, shown generally by the reference numeral 10 includes a plurality of radially extending side walls 11 which have top caps 13. Defining the particular workplaces are desk work surfaces 15 which allow for individual work spaces, shown generally in the figures. It should be noted that a variety of custom designed work spaces are available for various purposes such as accounting, word processing, general office work, light assembly, and other functions.
Each of the side walls 11 radiate from the ends of core walls 17 which together define a center core about which the work stations are centered. While a four sided core is shown in FIG. 2, it is to be appreciated that the number of core walls 17 can be varied from three or less to as many as eight or more sides. Each station is designed for the specific purposes of the consumer and the number of work spaces does not materially affect the present invention.
At the top of the column defined by the core walls 17 is a core lid 19 or 20. Contained within the core defined by the core wall 17 and the core lid 19 or 20 are, in addition to the present invention, other equipment. For example, electrical controls and electrical power is often directed to the central core area and access to that power or electrical equipment is through the core walls 17. Depending upon the needs of the work station, water, air or other gases, and the like can be provided from the central core defined by the core walls 17. Also, various forms of communication devices can be routed through that central core area.
In one embodiment, the air flow system of the present invention includes a top air grate 21 which is preferably formed in an egg crate design. For example, low cost polystyrene egg crate louvers are effective for use as the top air grates 21. More preferred is a solid core lid 20, shown in FIG. 8 and FIG. 9.
Air is taken into the central core area behind the core walls 17 through an intake vent 23. As will be described hereinafter, air is processed in the interior portion behind the walls 17 and is exhausted or expelled out of the core area through gaps 25 between the core wall 17 and the core lid 20. Gaps 25 are formed by spacers 27 which provide an elevation of the core lid 20 so that air is directed horizontally out over the top of the person in the work space.
As is easily seen in FIG. 3, the region defined by the core walls 17 is divided into an upper chamber and a lower chamber by a motor platform 29. Platform 29 is mounted to the sidewalls by support brackets 31 and can be lifted out of the central core as needed. Mounted on the lower portion of motor platform 29, in the lower chamber, is a filter 33, shown as being held by wing nut 35. Filter 33 is an exterior filter, such as would be useful for removing particulate and odor. The outer filter 33 is intended to filter large particles and will trap odor when activated charcoal and/or other odor absorbing materials are employed. Inside the filter 33 is a canister or other type air filter 37 which is known generally as a HEPA filter. These HEPA filters 37 are commercially available and have an efficiency of at least 99.97% at 0.3 microns, using a DOP test procedure.
As is noted, the motor platform 29 is positioned by brackets 31 at a point in the interior between walls 17 where the lower chamber is defined. This lower chamber receives air through intake vents 23 which, as shown in FIG. 3, are positioned above the desk work space 15. Typically, smoke from ashtrays would be drawn in through the intake vent 23 as is all of the ambient air adjacent the worker in the work space. Vents 23 are the only source of air for the apparatus of the present invention.
Motor platform 29 also supports the motor 39 and its motor bracket 41 in a chamber above platform 29. The chamber is enclosed by the platform 29, the core walls 17 and the core lid 19. This motor 39 is the sole source of air movement. Filtered, clean and deodorized air is produced through as it passes filters 33 and 37 and is exhausted by motor 39 into the upper chamber above the platform 29.
Some of the air in the upper chamber flows through the top grates 21 in a vertical direction while another major quantity of the air flows horizontally out through the gaps 25 defined by spacers 27. Air flowing through gaps 25 flows horizontally away from the core wall 17. The air leaving the vent or gap 25 flows over the work station and is pulled down as the air is drawn into the core through vent 23. This causes the formation of an air envelope which functions similar in nature to that of a cleanroom. In a preferred embodiment, the motor 39 is capable of moving at least 300 cubic feet per minute of air. When the device is operating at full capacity, it is possible to accomplish over 30 air changes per hour within a thirteen foot circle having its diameter at the center of the core.
It is recognized that not every worker requires or desires the same degree of air quality. Under some circumstances, it may be desirable to vary the amount of air which is forced by motor 39 up through the grates 21 in proportion to the amount of air exited through the gap 25 between the lid 19 and the wall 17.
An alternative embodiment shown in greater detail in FIG. 5 provides a baffle 43 which, in the extended position shown in FIG. 5, helps to direct air against the under surface of the lid 19 of FIG. 3 or lid 20 of FIG. 8 and out through gap 25 in a horizontal direction out over each of the work stations. Baffle 43 is connected via linkage 45 to a pull handle 47. C clamp 49 holds the handle 47 in whatever location is desired. Squeezing the two ends of C clamp 49 releases pressure on handle 47 and the location of baffle 43 can be changed, via linkage 45. If desirable, of course, the baffle can be pulled to a position which closes the gap 25 and no air is forced horizontally over that particular work station. Alternatively, a gap can be maximized as shown in FIG. 5. Of course, intermediate positions are also easily obtainable. Hinge 51 allows baffle 43 to move from one extreme to the other of its positions simply by adjusting the pull handle 47 and C clamp 49.
In the preferred embodiment shown in FIG. 8, the region defined by the core walls 17 is again divided into an upper chamber and a lower chamber by a motor platform 29. Platform 29 is mounted to the sidewalls by support brackets 31. Mounted on the lower portion of motor platform 29, in the lower chamber, is a filter assembly shown as being held by wing nut 35. Filter 34 is an exterior filter, such as would be useful for removing particulate and may be made from polyester or other synthetic filter materials. Filter 34 is intended to filter large particles. Inside filter 34 is another outer filter 33 which will trap odor when activated charcoal and/or other odor absorbing materials are employed. Inside the filter 33 is a canister or other type air filter 37, known generally as a HEPA filter. These HEPA filters 37 are commercially available and have an efficiency of at least 99.97% at 0.3 microns, using a DOP test procedure.
As has been noted, the lower chamber receives air through intake vents 23 which, as also shown in FIG. 8, are positioned above the desk work space 15. All of the ambient air adjacent the worker in the work space enter vent 23. Vents 23 are the only source of air for the apparatus of the present invention.
Motor platform 29 also supports the motor 39 and its motor brackets 41 in a chamber above platform 29. The chamber is enclosed by the platform 29, the core walls 17 and the core lid 20. This motor 39 is the sole source of air movement. Filtered, clean and deodorized air is produced through as it passes filers 34, 33 and 37 and is exhausted by motor 39 into the upper chamber above the platform 29.
Air is discharged in a common plane which is generally horizontal so that substantially all of the air flows horizontally out through the gaps 25 between wall 17 and lid 20, defined by spacers 27. Air flowing through gaps 25 flows horizontally in a common plane away from the core wall 17. The air leaving the vent or gap 25 flows over the work station and is pulled down as air is drawn into the core through bent 23. This causes the formation of an air envelope which functions similar in nature to that of a cleanroom.
FIG. 9 shows solid core lid 20, whereas the arrows in FIG. 8 shows air flow in a common plane leaving the core after being pulled through inlet 23, particle filter 34, odor filer 33 and HEPA filter 37. Outside the core, the envelope of air is clean filtered air.
The present invention addresses the concept of providing individual envelopes of clean, filtered air at each station to remove problems causing particles. Tests were made to determine the efficacy of the present invention. Specifically, particulate matter was measured at an office for specific regions, using the system shown in the drawings. These results were compared with space where only HVAC systems were run. Particle count in all of these tests is measured as number of particles of 0.5 microns or larger per cubic foot of air. Presented below in TEST SERIES ONE are the results of some tests which show the achievement of surprising and superior results.
______________________________________TEST SERIES 1 ParticleRoom Condition Date Time Count______________________________________HVAC only 11/29/90 2:10 p.m. 354,930HVAC only 11/29/90 2:40 p.m. 417,150HVAC only 11/29/90 3:40 p.m. 407,030Present Invention: Low Speed 11/30/90 2:00 p.m. 230,109Present Invention: High Speed 11/30/90 3:00 p.m. 63,470Present Invention: High Speed 11/30/90 3:15 p.m. 40,008Present Invention: High Speed 11/30/90 3:30 p.m. 27,777______________________________________
As can be seen, more than an order of magnitude of improvement was achieved by the use of the present invention. Adjacent rooms had counts on Nov. 29, 1990 and Nov. 30, 1990 of 464,110 and 418,420 for the first room and 614,120 and 220,680 for the second room. Remarkedly, the present invention was able to achieve a particle count under 100,000 for an office.
Similar tests were made in several offices in a hospital. Again the comparison is between ordinary HVAC and the present invention for particle count as defined above.
______________________________________TEST SERIES IIRoom/System Date Particle Count______________________________________Hospital Hall/HVAC 12/07/90 367,220Hospital Hall/HVAC 12/12/90 707,590Library/HVAC 12/07/90 126,350Library/HVAC 12/12/90 640,610Office/Present Invention 12/07/90 29,580Office/Present Invention 12/12/90 31,390Financial Area/Present Invention 12/07/90 33,500Financial Area/Present Invention 12/12/90 41,350______________________________________
As can be seen from the data above, particle count for both the office and financial area were remarkedly reduced, again below 100,000 particles per cubic foot of air. The importance of reducing particle count, whatever their level is seen in the correlation between particle count and "Sick Building Syndrome" where high sickness and/or absenteeism is caused by high particle count.
Programming the rate of air movement can provide a substantial increase in air quality. Accordingly, the present invention apparatus would be programed to operate at a rapid rate of at least 300 cubic feet per minute and would thereby accomplish at least 30 air changes per hour in the thirteen foot circle encompassing the present invention. As the employees report for work, the rate of air change can be decreased to maintain a steady state of clean air so that 10 to 30 complete air changes per hour are accomplished.
Under appropriate conditions, it has been shown to be possible to obtain a class 100,000 reading for an office, which is highly desirable for health reasons as well as insurance ratings. Properly operated, the present system reduces bacteria and cuts total particle count by a significant factor.
Another important factor is that each workspace becomes its own protected envelope of clean filtered air. In effect, the core and filters form a source of air which reaches out over the core centered workspaces like an umbrella of protection. The air flowing in the common plane forms the top of the umbrella, and as velocity is lost, becomes pulled down, enveloping the workplace, being drawn into vents 23. A suitable blend of fresh and filtered air is achieved.
The system is easily accessible for repair or reconditioning. Simple removal of the access panel 57 allows access to both filters. The prefilters 33 and 34 may be changed two or three times a year as part of routine maintenance. These prefilters extend the life of a HEPA filter which is recommended to be changed every two years. Of course, simply loosening wing nut 35 allows for quick removal of the HEPA filter 37 as well as for cleaning or replacement.
While various modifications and embodiments have been shown, it is recognized that a variety of embodiments are possible without departing from the spirit of the present invention.
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An apparatus for use with a multi-station workspace including a predetermined number of core walls which define an enclosed core. The core walls include an inlet at or below a predetermined height. The apparatus includes a platform positioned in the core at a location above the predetermined height substantially separating the core into a lower air intake chamber and an upper air discharge chamber. The platform further includes a filter in the lower chamber and a blowers drawing air from the intake chamber through the filter to the upper chamber. Finally, a core lid is positioned at the top of the core and includes air discharge vents. The discharge vents are side vents proximate each of the core walls for discharging air in a substantially horizontal direction out from each of the core walls to form an envelope of clean, filtered air for the workspace.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to electric motor control systems and more specifically to a voltage control method for use within an electric motor control system.
2. Description of the Related Art
In an electric motor control system such as, for example, that used in an electrically-propelled vehicle, an electric power converter typically converts electric energy between an electrical energy storage medium and the motor. In an electrically-propelled vehicle, the storage medium is generally a battery. The electric power converter converts the form of electric energy available in the storage medium (for example, direct current energy in a battery) into electric energy which can be used by the motor (for example, three-phase electrical power for use by a three-phase motor)
In order to prevent wasting energy in an electric motor control system, regeneration energy from the motor can be captured while the motor is decelerating. Such regeneration energy is generated by the motor and is converted by the electric power converter back into the form which can be stored by the storage medium.
However, an issue arises in providing regeneration energy back to the storage medium. Because an electric power converter typically comprises semiconductor switches, there is a voltage limit above which these switches should not be exposed. As with all semiconductor devices, the switches in an electric power converter can be damaged by overvoltage. As regeneration current is provided from the power converter to the storage medium, the terminal voltage at the power converter rises above the voltage of the storage medium. This is due to the I•R voltage across the bus connecting the power converter and the storage medium. Should the terminal voltage at the power converter rise such that the semiconductor switches within the power converter are exposed to an overvoltage condition, those switches can be damaged.
One proposed method for preventing the terminal voltage of an electrical power converter from excessively rising during a regenerative event is to simply measure and closed-loop-control the terminal voltage of the electrical power converter. That is, the terminal voltage is periodically measured and the regeneration current is reduced if necessary to prevent the terminal voltage from rising above a predetermined acceptable value.
However, such a method has drawbacks. In a control system which uses the terminal voltage at the power converter as the control variable, some amount of overshoot of that voltage is the price paid for acceptable speed of performance. This is a trade-off faced in any control system. Such overshoot could over time damage the semiconductor switches within the electric power converter. The overshooting can be tolerated if the target point for control of the terminal voltage of the electric power converter is reduced. However, this will also reduce the amount of available energy which is captured through regeneration.
Thus, a system and method which allow for very high efficiency in recapturing regeneration energy and which effectively protect the electric power converter from damage due to overvoltage will provide advantages over alternative systems.
SUMMARY OF THE INVENTION
The present invention provides a method for controlling regenerative energy in a system having an motor and having a power converter for converting regenerative energy from the motor for supply as electrical current to a receiving apparatus. The method comprises estimating a resistance to electrical current flow between the electrical power converter and the receiving apparatus and measuring a first voltage at the receiving apparatus. The method further comprises controlling a regenerative current from the power converter to the receiving apparatus in view of the resistance and the first voltage to limit a second voltage at the power converter.
The present invention can effectively prevent overvoltage within an electric power converter while allowing regeneration energy to be captured with high efficiency. In doing so, the present invention provides considerable advantages over alternative technologies.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a drive system for an electric vehicle.
FIG. 2 illustrates a control method performed by motor controller 16 of FIG. 1 to limit the voltage V bus at power converter 14.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Refer first to FIG. 1. There, a drive system for a typical electric vehicle is illustrated. The system includes a motor 10, which may be an AC or DC motor. The system also includes a source of electrical energy such as a battery 12. A power converter 14 converts the energy provided by battery 12 into a usable form for motor 10. For example, if motor 10 is a three-phase AC motor, power converter 14 will be a three-phase DC-to-AC inverter. A motor controller 16 controls power converter 14. For example, controller 16 controls the semiconductor switches which would convert the EC energy from battery 12 into three-phase AC energy for motor 10. Controller 16 is preferably a microprocessor-based device which uses any known motor control algorithm which is appropriate for the specific motor 10 employed in the system. When power converter 14 provides electrical current to motor 10, motor 10 produces mechanical torque for propelling the electric vehicle.
When current flows from motor 10 to power converter 14, however, motor 10 is operating in regenerative mode. This is the direction of current flow designated by the label "I mot " in FIG. 1. In regenerative mode, kinetic energy from the vehicle's motion drives motor 10 as a generator. Controller 16 controls power converter 14 to provide at least a portion of the regenerative energy to battery 12. Charging battery 12 with regenerative energy helps to extend the range of the electric vehicle.
Battery 12 and power converter 14 are electrically coupled by a bus 18 which conducts electrical energy between battery 12 and power converter 14. At power converter 14, the voltage across bus 18 is denoted V bus . At battery 12, the no-load terminal voltage of battery 12 is denoted E bat . The total resistance of bus 18 is denoted R bus . R bus includes all electrical resistance to current flow between battery 12 and power converter 14. This includes conductor resistance, resistance of any electrical couplings in bus 18 and the internal resistance of battery 12. Current flowing from power converter 14 to battery 12 during regeneration is denoted I bus .
Motor controller 16 has several inputs as shown in FIG. 1. V bus and I bus are provided through appropriate sensing means. Also, the temperature of battery 12 is sensed by an appropriate sensor located within or near battery 12. Alternatively, ambient temperature or other surrogates for battery temperature may be available. Also, other inputs to motor controller 16 may be used for the general purpose of motor control; such inputs are not detailed here for the sake of simplicity.
Power converter 14 typically contains electronic devices such as semiconductor switches. Those semiconductor switches may be, for example, field-effect transistors (FETs) or bipolar junction transistors (BJTs). Such devices have upper voltage thresholds above which they should not be exposed without damage to the devices. Thus, in the terminology of FIG. 1, V bus should be limited to an acceptable level.
In a method of limiting V bus to an acceptable level according to this embodiment of the present invention, it is recognized that V bus is equal to E bat plus the I•R drop across R bus . Thus, knowing E bat and knowing R bat (which can be estimated as will be described herein), a limit can be calculated for I bus such that the threshold for acceptable V bus is not exceeded. Controller 16 can then limit I bus accordingly.
Refer additionally to FIG. 2 for a detailed description of how controller 16 limits V bus according to this embodiment of the present invention. At block 100, controller 16 determines whether its estimate of R bus has been initialized. If YES, R bus is not initialized again. If NO, R bus is initialized at blocks 102, 104 and 106. At block 102, the state of charge of battery 12 is determined. The state of charge of battery 12 can be estimated by an ongoing integration of the current flowing into and out of battery 12. Alternatively or additionally, several state-of-charge estimation algorithms are known to those having skill in the art. At block 104, the temperature of battery 14 (or an appropriate surrogate for battery temperature) is examined. At step 106, then, the value of R bus is set to an initialization value R init R init is preferably looked up from a three-dimensional look-up table having the temperature and state of charge (SOC) of battery 12 as independent variables. Battery internal resistance is the dependent variable, and its relationship to battery temperature and SOC are known a priori with reasonable accuracy.
Using battery internal resistance as the initial bus resistance estimate R init assumes that the internal resistance of battery 12 dominates over conductor resistance and connector resistance in comprising R bus . This is the normal case and is a reasonable starting point for the estimate of R bus . However, connector resistance may increase over time with the effects of corrosion and of loosening connectors. Also, the battery internal resistance value looked up at step 106 may have inaccuracies. Thus, an ongoing calculation of R bus is then made, in order to improve the accuracy of the initial estimate.
At step 108, it is determined whether motor 10 is operating in regenerative mode. This, of course, is information known to motor controller 16. If motor 10 is operating in regenerative mode, an ongoing calculation of R bus occurs at step 110. Periodic samples of V bus and I bus are taken by controller 16 and are used to estimate R bus . Specifically, R bus can be estimated as: ##EQU1## where V bus (k) and V bus (k-1) are periodically-measured values of V bus and I bus (k) and I bus (k-1) are periodically-measured values of I bus .
At step 112, then, controller 16 calculates a limit I bus .sbsb.-- lim below which controller will limit the regenerative current supplied on bus 18 to battery 12. Recognizing that
V.sub.bus =E.sub.bat +I.sub.bus R.sub.bus,
I bus .sbsb.-- lim is calculated as follows: ##EQU2## where V bus .sbsb.-- lim is the predetermined voltage above which V bus should not be allowed to rise. Controller 16 controls the regenerative current provided to battery 12 to not exceed I bus .sbsb.-- lim . It should be noted that E bat is not directly measured per se. However, each time the current I bus is insignificantly small, such as when the vehicle is at rest or when the direction of flow of current I bus reverses, E bat is equal to V bat . At those times, the value of E bat stored in controller 16 can be updated.
Various other modifications and variations will no doubt occur to those skilled in the arts to which this invention pertains. Such variations which generally rely on the teachings through which this disclosure has advanced the art are properly considered within the scope of this invention. This disclosure should thus be considered illustrative, not limiting; the scope of the invention is instead defined by the following claims.
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A method for controlling regenerative energy in a system having an motor and having a power converter for converting regenerative energy from the motor for supply as electrical current to a receiving apparatus includes estimating a resistance to electrical current flow between the electrical power converter and the receiving apparatus and measuring a first voltage at the receiving apparatus. The method further comprises controlling a regenerative current from the power converter to the receiving apparatus in view of the resistance and the first voltage to limit a second voltage at the power converter.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to scoops and containers and, more particularly, to collapsible and disposable scoops and containers for collecting and disposing of animal waste and the like.
2. Description of the Prior Art
Scoops and containers for retrieving and disposing of animal waste may take a permanent and reusable form or a disposable form. Permanent and reusable scoops are primarily utilized by homeowners on their residential properties. Disposable scoops and containers are utilized on city and park lands where city ordinances require the collection and disposal of animal wastes.
The Allan et al U.S. Pat. No. 3,971,503 discloses a disposable scoop and container having an elongated, tubular body with a hinged cover. The cover doubles as a scoop to retrieve the waste and allow it to pass into the tubular body where it is contained. After the waste is deposited into the tubular body, the cover is locked to the body by bending a corner of the body and inserting a corner of the cover under the bent corner.
SUMMARY OF THE INVENTION
A feature of the present invention is a scoop that is erectable from a collapsed, compact form to an expanded, operational form. In the compact form the scoop is flat and in the operational form the scoop has the pair of jaws with waste-containable cavities formed therein.
Another feature of the present invention is a set of braces to lend rigidity to the jaws in the expanded form. The braces lie flat in the collapsed form and expand with the jaws to brace the scoop in its expanded, operational form.
Still another feature of the present invention is a pair of locking tabs to lock the jaws together after the waste has been collected. The locking tabs are connected to one jaw and are inserted into a pair of tab-receiving slots formed in the other jaw to lock the jaws.
Still another feature of the present invention is a pair of hinged jaws cooperating to retrieve and contain waste. Each jaw may have a set of teeth for readily scooping the waste and a cavity for containing the waste after it has been scooped.
An advantage of the present invention is that the scoop may be conveniently portable in its collapsed, compact form. In the compact form, the scoop is easily insertable into a pocket, which allows free use of the hands while walking one's pet.
Another advantage of the present invention is that the scoop is easily transformed from its compact form to its operational form. By folding the jaws outwardly, the scoop is expanded and the braces are moved automatically into position to rigidify the scoop for operation.
Still another advantage of the present invention is that the scoop may be operated by one hand to retrieve the waste, leaving one hand free to perhaps control a pet. A handle is connected to each jaw to allow each jaw to be independently controlled as the waste is being scooped.
Still another advantage of the present invention is a feature that allows one jaw to overlap the other. The overlapping feature not only ensures complete containment of the waste but in effect allows the waste to be scooped and collected almost simultaneously.
Still another advantage of the present invention is that the scoop may be locked to contain the waste. The locking tabs allow the waste to be safely contained until the scoop and its waste material can be disposed of properly.
Still another advantage of the present invention is that the scoop is disposable. It may be constructed from inexpensive disposable and biodegradable materials such as cardboard.
Still another advantage of the present invention is that the scoop is substantially one piece and its elements are substantially integrally connected. Therefore it may be efficiently stamped from materials such as cardboard.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a die-cut from which the scoop and container may be formed;
FIG. 2 is a perspective view of a first jaw of the scoop and container as it is being formed from the die-cut;
FIG. 3 is a perspective view of a second jaw of the scoop and container as it is being formed from the die-cut;
FIG. 4 shows a plan view of a jaw and in particular shows the braces lying flat and uncreased in the collapsed form of the scoop and container;
FIG. 5 shows a side view of the scoop and container in its collapsed, compact form;
FIG. 6 shows a perspective view of a jaw as it is being erected from a collapsed, compact form to the expanded operational form;
FIG. 7 shows a perspective view of the scoop and container in its expanded operational form; and
FIG. 8 is a perspective view of the scoop and container partially locked.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown by the die-cut in FIG. 1, a scoop and container 10 has a first jaw 100 and a second jaw 200. A linearly creaseable connection 101 hingedly and integrally connects the first and second jaws 100 and 200.
The first jaw 100 has a first main planar panel 114; panel 114 has four edges, 101 and 115-117, and is formed substantially, in the shape of a square. The edges 101 and 115-117 form the circumference of the square panel 114.
Edge 115 forms a linearly creaseable hinged connection to a first front planar panel 120. The hinged connection may extend for the entire length of edge 115.
The front panel 120 has a bottom edge 122, and a pair of side edges 123, 124. The panel 120 is formed substantially in the shape of a rectangle, although a set of teeth 125 may be integrally formed along the bottom edge 122.
A pair of braces 126 and 127 are connected to panel 120 along a creaseable hinged connection with edges 123 and 124.
Edges 132-136 form the outer circumference of brace 126. Edges 132 and 133 form a nub 137 which lies near the bottom edge 122 of panel 120. Edges 134 and 136 extend inwardly so that brace 126 tapers away from panel 120.
Edges 138-142 form the outer circumference of brace 127. Edges 138 and 139 form a nub 143 which lies near the bottom edge 122 of panel 120. Edges 140 and 142 extend inwardly so that brace 127 tapers away from panel 120.
A linearly creaseable hinged connection connects a side panel 145 to the edge 116 of the main panel 114. The hinged connection may extend along the entire length of edge 116.
The side panel 145 has a tab 150, but otherwise is formed in the shape of a triangle. A foldable linear crease 149 extends from the intersection of edges 116 and 148 to edge 147 at about a 45° angle from edge 116. Tab 150 is integrally connected to edge 148 of side panel 145; tab 150 is formed substantially in the shape of a trapezoid.
A linearly creaseable hinged connection connects a side panel 156 to the edge 117 of the main panel 114. Side panel 156 is formed essentially identically to side panel 145, with a tab 161 and a foldable linear crease 160.
The second jaw 200 has a second main planar panel 214 integrally connected to the first jaw 100 along edge 101. The panel 214 has four edges 101, 215-217, and is formed substantially in the shape of a square.
A linearly creaseable connection hingedly and integrally connects a bottom edge of a second front panel 220 to edge 215 of main panel 214. The hinged connection may extend for the entire length of edge 215.
The front panel 220 has a top edge 222, and a pair of side edges 223, 224. The panel 220 is formed substantially in the form of a rectangle, although a second set of teeth 225 may be integrally formed along to edge 222.
A pair of braces 226, 227 are connected to panel 220. A linearly creaseable connection along edge 223 hingedly and integrally connects the brace 226 to panel 220. The hinged connection may extend partially along the length of edge 223. A linearly creaseable connection along edge 224 hingedly and integrally connects the brace 227 to the panel 220. The hinged connection may extend partially along the length of edge 224.
Edges 232-236 form the outer circumference of brace 226. Edges 232 and 233 form a nub 237 which lies near the top edge 222 of panel 220. Edges 234 and 236 extend inwardly so that brace 226 tapers away from panel 220.
Edges 238-242 form the outer circumference of brace 227. Edges 238 and 239 form a nub 243 which lies near the top edge 222 of panel 220. Edges 240 and 242 extend inwardly so that brace 227 tapers away from panel 220.
A linearly creaseable hinged connection along edge 216 integrally connects a side panel 245 to the main panel 214. The hinged connection may extend along the entire length of edge 216.
The side panel is formed in the shape of a triangle. Edges 247 and 248 form acute angles with edge 216. A foldable linear crease 249 extends from the intersection of edges 216 and 248 to edge 247 at about a 45° angle from edge 216.
A linearly creaseable hinged connection along edge 217 integrally connects a side panel 256 to the main panel 214. The hinged connection may extend along the entire length of edge 217.
The side panel 256 is formed in the shape of a triangle. Edges 258, 259 form acute angles with edge 217. A foldable linear crease 260 extends from the intersection of edges 217 and 259 to edge 258 at about a 45° angle from edge 217.
A pair of U-shaped perforations 250-251 are formed in front panel 220. The perforations 250-251 extend inwardly from the respective edges 223, 224 to form a pair of extensions to the respective braces 226 and 227. A pair of tab-receiving slots 254, 255 are formed in the front panel 220 by the respective U-shaped perforations 250-251 when the scoop is in the expanded form as shown in FIG. 8.
A pair of handles 301-302 (FIG. 7) are connected to the first and second jaws 100 and 200 respectively. Handle 301 is connected to the outer face of panel 114 and handle 302 is connected to the outer face of panel 214. Handles 301-302 have a plurality of respective transverse creases 311-314 and 321-324 as shown in FIGS. 7 and 8. The creases 311-314 and 321-324 allow the handles 301-302 to lie flat in the compact, collapsed form as shown in FIG. 5 and to expand to an operational form as shown in FIG. 7 so that the scoop and container 10 may be operated by one hand.
As shown in FIG. 2, a first scoop opening or cavity 175 is formed by folding the panels 120, 145 and 156 upwardly along the creaseable edges 115, 116 and 117 respectively. In forming the first scoop opening 175, a first step may be to fold panel 120 upwardly along hinged edge 115. After the panel 120 has been folded to an acute angular relationship with main panel 114, braces 126 and 127 are folded inwardly along creaseable edges 123 and 124 respectively so that edge 136 of brace 126 lies linearly adjacent edge 116 and edge 142 of brace 127 lies linearly adjacent edge 117. After the braces 126, 127 have been folded into place, side panels 145 and 156 are folded upwardly along edges 116, 117 respectively so that the inside faces of the side panels 145 and 156 lie adjacent the outside faces of the braces 126 and 127.
After the side panels 145-156 have been folded to lie facially adjacent the braces 126-127, the side panels 145 and 156 are connected to the braces 126-127, respectively. A portion 176 of the inside face of side panel 145, as defined by linear crease 149, is facially connected, as by gluing, to the outside face of brace 126. A portion 177 of the inside face of the side portion 156, as defined by linear crease 160, is facially connected, as by gluing, to the outside face of brace 127. FIG. 2 shows panel 145 in the process of being folded upwardly to connect with brace 126 and panel 156 connected to brace 127 with tab 161 protruding beyond a plane defined by the front panel 120.
As shown in FIG. 3 a second scoop opening or second cavity 275 is formed from panels 214, 220, 245 and 256. First, to form cavity 275, panel 220 may be folded upwardly along edge 215 to an acute angular relationship with panel 214. Second, braces 226 and 227 are folded inwardly along edges 223 and 224 respectively so that edge 236 lies linearly adjacent edge 216, and edge 242 lies linearly adjacent edge 217. Third, side panels 245 and 256 are folded upwardly along edges 216, 217 respectively. Fourth, a portion 276 of the inside face of side panel 245, as defined by linear crease 249, is facially connected, as by gluing, to brace 226. Fifth, a portion 277 of the inside face of side panel 256 as defined by linear crease 260, is facially connected, as by gluing, to the outside face of brace 227. FIG. 3 shows panel 256 connected to brace 227 and panel 245 in the process of being folded to connect to brace 226.
To fold the scoop 10 into a collapsed form as shown in FIGS. 4 and 5 from the erected, fabricated form as shown in FIGS. 2 and 3, the side panels 145, 156, 245 and 256 are folded inwardly along their respective hinged edges 116, 117, 216 and 217, and along their respective linear creases 149, 160, 249 and 260. As the side panels 145, 156, 245 and 256 are folded inwardly, the braces 126, 127, 226 and 227 also fold inwardly to the inside faces of front panels 120 and 220 along hinged edges 123, 124, 223 and 224. As the side panels 145, 155, 245 and 255 and braces 126, 127, 226 and 227 are being folded inwardly front panels 120 and 220 also begin to fold inwardly until the scoop 10 lies flat. FIG. 5 also shows a further fold line 500, which may be used to enable scoop 10 to be folded into a package of smaller size.
As shown in FIG. 4, the braces 226 and 227 lie in a planar orientation in the collapsed, compact form of the scoop 10. The portions 276 and 277 of the side panels 245 and 256 remain facially connected to braces 226 and 227 respectively in the collapsed form.
As shown in FIG. 6, the scoop 10 is erectable from the collapsed, compact form to an expanded, operation form by folding outwardly the side panels 145, 156 and 245, 256. As the side panels are being folded outwardly the braces move outwardly to lie facially adjacent the inside faces of side panels. As the braces move outwardly, the edges of the braces may slide frictionally along the inside face of main panels 114, 214. Braces 126 and 127 support side panels 145 and 156 in an open, expanded position relative to main panel 114, to form cavity 175. It will be appreciated that the second jaw 200 is erected in substantially the same manner as first jaw 100.
The scoop and container 10 is in an operational form as shown in FIG. 7. The scoop 10 may be opened and closed by one hand along hinged edge 101. The waste material is collected by closing the first and second jaws 100, 200 until the first jaw 100 is recessed into the second jaw 200.
When the waste material is collected and the first jaw 100 is recessed in the overlapping second jaw 200, the jaws 100 and 200 may be interlocked by the insertion of the tabs 150 and 161 into the respective tab-receiving slots 254 and 255, thereby locking the waste material in the cavities 175, 275 for disposal. The canted edges of the tabs 150 and 161 allow the tabs 150 and 161 to slide readily against the inside face of front panel 220 and through the slots 254 and 255 as the first jaw 100 is being recessed into the second jaw 200.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.
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A disposable scoop and container having a pair of foldable hinged panels, each of the panels having foldable side panels and a front panel, which may be folded into compact flat form and may be unfolded to form a scoop cavity, wherein one of the scoops may be recessible into the other scoop, and locking tabs for holding one scoop in recessed locked position within the other scoop.
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CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
This application claims benefit to International Application No. PCT/EP02/06828 filed on Jun. 20, 2002, and published in the English language under PCT Article 21(2); German application no. DE20110342.7, filed Jun. 22, 2001, all of which are incorporated herein by these references.
BACKGROUND
The present invention relates to a head restraint arrangement for a vehicle seat comprising a backrest and a lower seat surface part, having a head-supporting part which is connected or can be connected to the backrest via retaining means.
The invention furthermore also relates to a vehicle seat fitted with a head restraint arrangement of this type, having a lower seat surface part and a backrest which can be folded over.
It is known to provide vehicle seats with head restraints which are intended to protect the seat user against accident-included injuries in the region of the cervical vertebrae, i.e. against “whiplash”. It has also been known from a long time to guide the head restraint on or in the backrest in a manner such that it can be adjusted in height via restraining means and such that it can be locked in different positions in order to adapt it to users of differing size.
In many cases, it is intended that vehicle seats can be changed between different positions to utilize the vehicle in a variable manner. In this case, because of the head restraint which is arranged protruding in the upper region, folding the backrest over in particular frequently causes problems in respect of possible collisions with other vehicle parts. Sometimes, the head restraint even has to be entirely removed before the backrest is folded over.
SUMMARY
The present invention is based on the object of providing a head restraint arrangement of the above-mentioned type and a seat fitted with said head restraint arrangement, with which a particularly easy change in the arrangement of the seat and its parts is possible.
According to the invention, this is achieved first of all in accordance with the claims by the fact that the retaining means are designed in such a manner that the head-supporting part can be transferred between an operative position, which is arranged in accordance with its head-supporting function above the backrest, and an inoperative position and is locked releasably in both positions, the head-supporting part, in the inoperative position, firstly being lowered relative to the operative position, in the direction of the seat surface part and, secondly, being arranged lying in the region of a backrest front side in front of the backrest.
A vehicle seat fitted with a novel head restraint arrangement of this type is distinguished in accordance with the claims by the fact that, starting from an operative position, which is suitable for sitting, the seat surface part can be folded over through approximately 180° about a transverse axis, which is arranged in its front region away from the backrest, in such a manner that it lies with its lower side, which points upward, in a plane with an adjacent loading floor of the vehicle, it being possible, in the inoperative position of the head-supporting part, for the backrest to be folded over through approximately 90° about a lower transverse axis in the direction of the seat surface part, and it then lying with its rear surface likewise approximately in the plane of the loading floor. In this case, it is expedient, firstly, for the backrest together with the head-supporting part situated locked in the inoperative position, to be accommodated, in the folded-over position of the backrest, and, secondly, for the lower seat surface part with its seat cushion in the inverted position to be accommodated in each case in a trough-like receptacle of the vehicle.
The invention makes a transfer between the operative and inoperative position very simple and comfortable; a complete removal of parts, such as, in particular, the head restraint, can be rendered superfluous, so that there is also no risk of any part being lost; on the contrary, all of the components are always available to the user in the vehicle for use in a variable manner. During the transfer of the backrest into the folded-over position of the backrest, the locking according to the invention of the head restraint part in its inoperative position, which is situated in front of the backrest, is of particularly advantageous importance because it reliably avoids uncontrolled oscillating movements and resultant problems when introducing or placing the head restraint part into the associated receiving trough of the vehicle without the head restraint part here having to be secured or guided awkwardly by hand.
Further advantageous design features and advantages of the invention achieved thereby are contained in the subclaims, which are dependent on claims and 33 , and in the following description.
DESCRIPTION OF DRAWINGS
The invention will be explained more precisely with reference to a preferred exemplary embodiment which is illustrated in the drawing, in which:
FIG. 1 shows a schematic, partially cutaway side view of a vehicle seat with a head restraint arrangement according to the invention, with different positions of the components being illustrated simultaneously,
FIG. 2 shows an enlarged view just of the head-supporting part, in a view corresponding to FIG. 1 ,
FIG. 3 shows a front view of the head-supporting part in the arrow direction III according to FIG. 2 (likewise illustrated partially cut away and transparently),
FIG. 4 shows a schematic sectional view in the plane IV—IV according to FIG. 3 in different positions of the head-supporting part during the transfer between its two positions,
FIG. 5 shows a section in the plane V—V according to FIG. 3 ,
FIG. 6 shows a view analogous to FIG. 3 just of an inner supporting housing of the head-supporting part together with the upper region of a retaining-rod element,
FIG. 7 shows a section in the central plane VII—VII according to FIG. 6 ,
FIG. 8 shows a section in the plane VIII—VIII according to FIG. 6 ,
FIG. 9 shows a section in the plane IX—IX according to FIG. 6 ,
FIG. 10 shows a further section in the plane X—X according to FIG. 6 , and
FIG. 11 shows a perspective exploded illustration of the functionality essential parts of the head restraint arrangement according to the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
In the various figures of the drawing, identical parts and components are always provided with the same reference numbers, and so they are generally also only described once in each case.
FIG. 1 illustrates a vehicle seat 2 which comprises a backrest 4 and a lower seat surface part 6 and has a head restraint arrangement 8 according to the invention. A head-supporting part 12 is connected or can be connected to the backrest 4 via retaining means 10 .
As can furthermore be gathered from FIG. 1 , the retaining means 10 are designed in such a manner that the head-supporting part 12 can be transferred between an operative position A, which is arranged in accordance with its head-supporting function above the backrest 4 , and an inoperative position B and is locked releasably in both positions A, B. In the inoperative position B, the head-supporting part 12 is, firstly, lowered relative to the operative position A in the direction of the lower seat surface part 6 and, secondly, is arranged lying in the region of a backrest front side 14 in front of the backrest 4 . In this manner, the invention eliminates the projecting length, which is necessary in the operative position A, of the head-supporting part 12 protruding upward above the backrest 4 by, in the inoperative position B, no parts of the head-supporting part 12 protruding any more over the backrest 4 .
It is expedient for the invention if the retaining means 10 have a retaining-rod element 16 having two retaining rods 20 , 22 which are parallel to each other and are guided in a longitudinally displaceable manner in guides 18 of the backrest 4 (which can only be seen in FIG. 1 ). In addition, the retaining rods 20 , 22 , which can be displaced in the guides 18 , can be locked in at least two, preferably, for the purpose of adjusting the height, in a plurality of, different positions. The retaining rods 20 , 22 are connected to each other, in particular in one piece via a transverse web 24 , in their end region which is situated outside the backrest 4 and the guides 18 . The retaining rods 20 , 22 are designed here such that they are curved “in the manner of a walking stick” in their upper end region in the transition to the transverse web 24 in such a manner that the transverse web 24 is arranged offset with respect to a guide plane 26 , which is defined by the two parallel retaining rods 20 , 22 (see, in this respect, FIGS. 2 and 4 , for example), in the direction of the backrest front side 14 .
The head-supporting part 12 is guided via a bearing arrangement 28 on the transverse web 24 of the retaining-rod element 16 in a manner such that it can be pivoted about an axis of rotation 30 , which is defined by the transverse web 24 or is identical with the longitudinal central axis of the transverse web 24 , and in a manner such that it can be locked in (at least) two different positions. In the preferred exemplary embodiment, the head-supporting part 12 can be pivoted through approximately 180° and can be locked alternatively in two positions, specifically either in a supporting position C extending upward approximately as an elongation of the retaining rods 20 , 22 (see FIGS. 2 and 4 ) or in a rest position D which, starting from the transverse web 24 , extends in an inverted manner downward approximately parallel to the retaining rods 20 , 22 (see FIG. 4 in this respect where the process of pivoting it over between the positions C and D is illustrated with reference to numerous intermediate positions). Furthermore, it is expedient, for the transfer of the head-supporting part 12 from the operative position A into its inoperative position B ( FIG. 1 ) if it is arranged with a central plane 34 , which runs approximately parallel to a front head-supporting surface 32 (see FIG. 4 ), asymmetrically with respect to the axis of rotation 30 in such a manner that the pivoting between the supporting position C and the rest position D causes it to be offset in each case with respect to the axis of rotation 30 . In the supporting position C, the central plane 34 is situated, according to FIG. 4 , behind the axis of rotation 30 and, in the rest position D, the central plane 34 is situated in front of the axis of rotation 30 . As a result, the head-supporting part 12 is positioned, as it is being lowered by pushing the retaining rods 20 , 22 into the guides of the backrest 4 , in front of the backrest front side 14 of the backrest 4 (inoperative position B according to FIG. 1 ).
The bearing arrangement 38 has a bearing part 36 which sits in a rotationally fixed manner, i.e. secured against rotation, on the transverse web 24 of the retaining-rod element 16 and on which an inner supporting housing 38 of the head-supporting part 12 is guided rotatably. As emerges from FIG. 11 , the bearing part 36 is expediently composed of two halves 36 a and 36 b which are connected to each other enclosing the transverse web 24 . This can take place on one side by a form-fitting engagement of a retaining web 40 of the one bearing-part half 36 a in a corresponding retaining opening 42 in the other bearing-part half 36 b , the two halves being connected on the other side, for example, by means of a rivet 44 or similar connecting element (in addition to FIG. 11 also see FIG. 8 ). For the bearing part 36 to sit in a rotationally secure manner on the transverse web 24 , form-fitting means are provided, in particular, for example, according to FIG. 11 , at least one projecting lug 46 of the transverse web 24 , which engages in a corresponding holder within the bearing part 36 (also see FIG. 8 ). The supporting housing 38 sits with inner bearing sections 47 a rotatably on two lateral bearing sections 47 b of the bearing part 36 ( FIG. 11 ). In this case, the supporting housing 38 comprises two housing parts 38 a and 38 b which are connected, for example screwed and/or latched, to each other enclosing the bearing part 36 .
A locking device 48 which interacts with the bearing part 36 and is intended for the supporting position and the rest position is provided within the supporting housing 38 . This locking device has a bolt slide 50 which is guided displaceably in the supporting housing 38 and uses at least one bolt element 52 to engage, either in the supporting position C or in the rest position D, in a respectively corresponding bolt opening 54 in the bearing part 36 (see in particular FIG. 10 in this respect). As emerges, for example, from FIGS. 5 , 7 and 8 , the bolt slide 50 is guided in a slide holder 56 formed within the supporting housing 38 . the bolt slide 50 preferably has two laterally offset bolt elements 52 . Two bolt openings 54 are accordingly also provided in each case for the two positions C and D. The bolt slide 50 is acted upon here with a spring force F 1 in the direction of its locking position. According to FIGS. 5 , 7 , 8 and 11 , a helical compression spring 58 , for example, is arranged for this purpose between the bolt slide 50 and the slide holder 56 of the supporting housing 38 .
The bolt slide 50 interacts with an actuating element 60 which is accessible from the outside for, preferably, manual actuation by pushing, in particular an actuating element in the manner of a push-button. This actuating element 50 is preferably arranged in a region of the head-supporting part 12 which, in the supporting position C, points downward in the direction of the backrest 4 and, in the rest position D, points upward in the opposite direction. This makes practical, very comfortable actuation possible. By means of the actuating element 60 , the bolt slide 50 can be displaced in the direction of a displacement axis or displacement plane 62 which, in the supporting position C, is arranged lying approximately parallel to the guide plane 26 , in the region situated between the guide plane 26 of the retaining rods 20 , 22 and the axis of rotation 30 . Reference is made in this respect to FIG. 2 , in particular.
It is furthermore advantageous if the head-supporting part 12 is acted upon with a rotational spring force F 2 in such a manner that—in each case after the lock is released—the pivoting in the one direction of rotation takes place counter to the rotational spring force F 2 by means of an external actuating force (in particular manually) which exceeds the latter and takes place in the other direction of rotation essentially automatically by means of the rotational spring force F 2 . In the preferred exemplary embodiment, the rotational spring force F 2 is directed in such a manner that, starting from the rest position D, the supporting position C is automatically reached by the spring force F 2 after the lock is released. However, an inverted variant is also included within the scope of the invention. As emerges from FIGS. 9 and 11 , in order to produce the rotational spring force F 2 , a torsion spring 64 is provided which is designed, for example, as a coiled leg spring and is arranged supported coaxially with respect to the axis of rotation 30 between the head-supporting part 12 or the interior of the supporting housing 38 , on the one hand, and the retaining-rod element 16 or the bearing part 36 , on the other hand.
As furthermore emerges from FIG. 1 , the head restraint arrangement 8 according to the invention is preferably designed for a vehicle seat 2 of this type which can likewise be transferred between an operative position, which is suitable for sitting, and an inoperative position. For transfer into the inoperative position, the seat surface part 6 can be folded over through approximately 180° in the arrow direction 68 about a transverse axis 66 , which is arranged in its front region away from the backrest 4 , in such a manner that it lies with its lower side 70 , which then points upward, approximately in a plane 72 with an adjacent loading floor of the vehicle. In addition, in the locked inoperative position B of the head-supporting part 12 , the backrest 4 can be folded over through approximately 90° in the arrow direction 76 about a lower transverse axis 74 in the direction of the seat surface part 6 , so that it then lies with its rear surface 78 likewise approximately in the plane 72 of the loading floor. This configuration enables the vehicle seat 2 to be used, in particular, as an additional seat, spare seat or child's seat, specifically, in particular, in an arrangement in the rear region of the vehicle, in which it is oriented rearward with respect to the actual direction of travel. The backrest 4 , with the head-supporting part 12 situated locked in the inoperative position B is accommodated, in the folded-over position of the backrest, in a trough-like receptacle of the vehicle. the same also applies for the seat surface part 6 , which, in its folded-over position with its upholstery downward, is situated in a floor trough. Both seat parts 4 , 6 then use their rear or lower sides 70 , 78 to supplement the loading area of the vehicle.
Owing to the limited structural space in the rear region of the vehicle, the backrest 4 of a spare seat of this type may be designed to be only relatively low or short. In the case of the dummy which is illustrated in FIG. 1 of a female of the “5 th percentile”, the backrest 4 reaches with its upper edge only approximately as far as the lower edges of the shoulder blades. The head restraint arrangement 8 according to the invention is therefore required in order to provide the occupant, in her sitting position which is turned rearward, with sufficient grip in the head and neck region during braking maneuvers.
The invention is not confined to the exemplary embodiments illustrated and described, but also encompasses all variants of equivalent effect within the meaning of the invention. Furthermore, the invention is also not yet confined to the combination of features defined in the claims but can also be defined by any other desired combination of particular features of all disclosed individual features.
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A headrest arrangement for a vehicle seat consisting of a back and a bottom seating part. Said arrangement comprises a headrest part that is connected to the back of the seat, with the connection configured in such a way that the headrest part can be moved between an in-use position arranged above the back of the seat and corresponding to its headrest function and a non-use position wherein the headrest part can be releasably locked in both positions. The headrest part in non-use position and relative to the in-use position is lowered in the direction of the seating part and is arranged horizontally in the area of the front part of the back of the seat. The invention also relates to a vehicle seat fitted with said headrest arrangement.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. application Ser. No. 12/411,882 filed Mar. 26, 2009, which is a continuation application of U.S. application Ser. No. 11/526,120 filed Sep. 25, 2006, now U.S. Pat. No. 7,557,328, issued on Jul. 7, 2009. This application is related to U.S. Pat. No. 7,230,204, issued on Jun. 12, 2007; U.S. application Ser. No. 11/525,818, filed Sep. 25, 2006; U.S. Pat. No. 7,297,894, issued on Nov. 20, 2007, and U.S. application Ser. No. 11/525,815, filed Sep. 25, 2006. The entire contents of these applications are herein incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for temperature control of a substrate, and more particularly to a method of using a substrate holder for temperature control of a substrate.
2. Description of Related Art
It is known in semiconductor manufacturing and processing that various processes, including for example etch and deposition processes, depend significantly on the temperature of the substrate. For this reason, the ability to control the temperature of a substrate and controllably adjust the temperature of the substrate is becoming an essential requirement of a semiconductor processing system. The temperature of a substrate is determined by many processes including, but not limited to, substrate interaction with plasma, chemical processes, etc., as well as radiative and/or conductive thermal exchange with the surrounding environment. Providing a proper temperature to the upper surface of the substrate holder can be utilized to control the temperature of the substrate.
SUMMARY OF THE INVENTION
The present invention relates to a system for controlling the temperature of a substrate.
According to one embodiment, a method of using a substrate support is described, the substrate support comprising one or more heating elements separated from one or more cooling elements by a thermal insulator.
According to another embodiment, a method for controlling the temperature of a substrate in a substrate processing system is described, the substrate processing system including a substrate holder for supporting the substrate and having a temperature sensor reporting a temperature at a region of the substrate and a heating element heating the region and being controlled by a temperature control system to control the temperature of the substrate using a PID control algorithm. The method includes selecting a first set-point temperature, selecting a second set-point temperature, selecting a first PID parameter set including a first proportional constant K P1 , a first integral constant K I1 and a first derivative constant K D1 , and selecting a second PID parameter set including a second proportional constant K P2 , a second integral constant K I2 and a second derivative constant K D2 . The substrate is placed on the substrate holder, the temperature of the substrate is adjusted to the first set-point temperature and the substrate is processed for a first period of time at the first set-point temperature. The temperature of the region of the substrate is changed from the first set-point temperature to the second set-point temperature using the first PID parameter set for a first ramp period of time and using the second PID parameter set for a second ramp period of time, the second ramp period of time following the first ramp period of time. The substrate is then processed for a second period of time at the second set-point temperature.
According to yet another embodiment, a method for controlling the temperature of a substrate in a substrate processing system is described, the substrate processing system including a substrate holder for supporting the substrate and having a plurality of temperature sensors reporting at least a temperature at an inner region and an outer region of the substrate, and first and second heating elements heating respectively the inner region and the outer region, the first and second heating elements being controlled by a temperature control system using a PID controller to maintain the substrate holder at a selectable set-point temperature. The method includes selecting a first inner set-point temperature and a first outer set-point temperature, selecting a second inner set-point temperature and a second outer set-point temperature, selecting a first inner PID parameter set including a first inner proportional constant K Pinner1 a first inner integral constant K Iinner1 and a first inner derivative constant K Dinner1 , selecting a second inner PID parameter set including a second inner proportional constant K Dinner2 , a second inner integral constant K Iinner2 and a second inner derivative constant K Dinner2 ;. Also included is selecting a first outer PID parameter set including a first outer proportional constant K Pouter1 a first outer integral constant K Iouter1 and a first outer derivative constant K Douter1 ; selecting a second outer PID parameter set including a second outer proportional constant K Pouter2 , a second outer integral constant K Iouter2 and a second outer derivative constant K Douter2 ;. The substrate is placed on the substrate holder and the inner region of the substrate is heated to the first inner set-point temperature and the outer region of the substrate is heated to the first outer set-point temperature, and the substrate is processed for a first period of time at the first inner and outer set-point temperatures. The temperature of the inner region of the substrate is changed from the first inner set-point temperature to the second inner set-point temperature using the first inner PID parameter set for a first inner ramp period of time and using the second inner PID parameter set for a second inner ramp period of time, the second inner ramp period of time following the first inner ramp period of time, and the temperature of the outer region of the substrate is changed from the first outer set-point temperature to the second outer set-point temperature using the first outer PID parameter set for a first outer ramp period of time and using the second outer PID parameter set for a second outer ramp period of time, the second outer ramp period of time following the first outer ramp period of time. The substrate is then processed for a second period of time at the second inner and outer set-point temperatures.
Another aspect of the invention includes a method of changing the temperature of a substrate during processing of the substrate. The method includes providing the substrate on a substrate holder, the substrate holder including a temperature controlled substrate support for supporting the substrate, a temperature controlled base support for supporting the substrate support and a thermal insulator interposed between the temperature controlled substrate support and the temperature controlled base support. The method also includes setting the temperature of the base support to a first base temperature corresponding to a first processing temperature of said substrate, setting the substrate support to a first support temperature corresponding to said first processing temperature of said substrate and setting the temperature of the base support to a second base temperature corresponding to a second processing temperature of said substrate. The substrate support temperature is then changed to a second support temperature corresponding to said second processing temperature of said substrate by selecting a first PID parameter set including a first proportional constant K P1 , a first integral constant K I1 and a first derivative constant K D1 , selecting a second PID parameter set including a second proportional constant K P2 , a second integral constant K I2 and a second derivative constant K D2 , and changing the temperature of said substrate from said first set-point temperature to said second set-point temperature using said first PID parameter set for a first ramp period of time and using said second PID parameter set for a second ramp period of time, said second ramp period of time following said first ramp period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 presents a block diagram of a substrate processing system according to an embodiment of the present invention;
FIG. 2A presents a schematic cross-section view of a substrate holder according to an embodiment of the present invention;
FIG. 2B illustrate exemplary profiles in thermal conductivity and substrate temperature for a substrate holder;
FIG. 3 . presents a schematic cross-section view of a substrate holder according to another embodiment of the present invention;
FIG. 4 . presents a schematic cross-section view of a substrate holder according to another embodiment of the present invention;
FIG. 5 . presents a schematic cross-section view of a substrate holder according to another embodiment of the present invention;
FIG. 6 . presents a schematic cross-section view of a substrate holder according to another embodiment of the present invention;
FIGS. 7A and 7B illustrate exemplary time traces of temperature; and
FIG. 8 illustrates a flow chart of a method of adjusting a substrate temperature according to an embodiment of the present invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as a particular geometry of the substrate holder for a substrate processing system and descriptions of various components and processes. However, it should be understood that the invention may be practiced in other embodiments that depart from these specific details.
According to an embodiment of the present invention, a material processing system 1 is depicted in FIG. 1 that includes a process tool 10 having a substrate holder 20 and a substrate 25 supported thereon. The substrate holder 20 is configured to provide temperature control elements for adjustment of substrate temperature. Additionally, the temperature control elements may be spatially arranged in order to ensure a uniform or non-uniform substrate temperature. A controller 55 is coupled to the process tool 10 and the substrate holder 20 , and is configured to monitor, adjust and control the substrate temperature as will be further discussed below.
In the illustrated embodiment depicted in FIG. 1 , the material processing system 1 can include an etch chamber. For example, the etch chamber can facilitate dry plasma etching, or, alternatively, dry non-plasma etching. Alternately, the material processing system 1 includes a photo-resist coating chamber such as a heating/cooling module in a photo-resist spin coating system that may be utilized for post-adhesion bake (PAB) or post-exposure bake (PEB), etc.; a photo-resist patterning chamber such as a photo-lithography system; a dielectric coating chamber such as a spin-on-glass (SOG) or spin-on-dielectric (SOD) system; a deposition chamber such as a vapor deposition system, chemical vapor deposition (CVD) system, plasma enhanced CVD (PECVD) system, atomic layer deposition (ALD) system, plasma enhanced ALD (PEALD) system, or a physical vapor deposition (PVD) system; or a rapid thermal processing (RTP) chamber such as a RTP system for thermal annealing.
Referring now to FIG. 2A , a substrate holder is described according to one embodiment. The substrate holder 100 comprises a substrate support 130 having a first temperature and configured to support a substrate 110 , a temperature-controlled support base 120 positioned below substrate support 130 and configured to be at a second temperature less than the first temperature (e.g. less than a desired temperature of substrate 110 ), and a thermal insulator 140 disposed between the substrate support 130 and the temperature-controlled support base 120 . Additionally, the substrate support 130 comprises one or more heating elements coupled thereto (not shown), and configured to elevate the temperature of the substrate support 130 (e.g. to heat the substrate). It is to be understood that the first temperature may be part of a temperature gradient across the substrate support and the second temperature may be part of a temperature gradient across the temperature controlled base according to embodiments of the invention.
According to one embodiment, the thermal insulator 140 comprises a thermal conductivity lower than the respective thermal conductivities of both the substrate support 130 and the temperature-controlled support base 120 . For example, the thermal conductivity of the thermal insulator 140 is less than 1 W/m−K. Desirably, the thermal conductivity of the thermal insulator ranges from approximately 0.05 W/m−K to approximately 0.8 W/m−K and, more desirably, the thermal conductivity of the thermal insulator ranges from approximately 0.2 W/m−K to approximately 0.8 W/m−K.
The thermal insulator 140 can comprise an adhesive made of polymer, plastic or ceramic. The thermal insulator 140 may include an organic or an inorganic material. For example, the thermal insulator 140 can comprise a room-temperature-vulcanizing (RTV) adhesive, a plastic such as a thermoplastic, a resin such as a thermosetting resin or a casting resin (or pourable plastic or elastomer compound), an elastomer, etc. In addition to providing a thermal resistance between the substrate support 130 and the temperature-controlled support base 120 , the thermal insulator 140 may provide a bond layer or adhesion layer between the substrate support 130 and the temperature-controlled support base 120 .
The thickness and material composition of the thermal insulator 120 should be selected such that, when necessary, adequate radio frequency (RF) coupling between the support base 120 and plasma can be maintained. Furthermore, the thermal insulator 120 should be selected in order to tolerate thermal-mechanical shear driven by thermal gradients and differences in material properties, i.e., coefficient of thermal expansion. For example, the thickness of the thermal insulator 140 can be less than or equal to approximately 10 mm (millimeters), and desirably, the thickness can be less than or equal to approximately 5 mm, i.e., approximately 2 mm or less.
Additionally, the material composition of the thermal insulator 140 is preferably such that it demonstrates erosion resistance to the environment within which it is utilized. For example, when presented with a dry plasma etching environment, the thermal insulator 140 should be resistant to the corrosive etch chemistries used during the etching process, as well as the corrosive cleaning chemistries used during an etch system cleaning process. In many etching chemistries and cleaning chemistries, halogen-containing process gases are utilized including, but not limited to, Cl 2 , F 2 , Br 2 , HBr, HCl, HF, SF 6 , NF 3 , ClF 3 , etc. In these chemistries, particularly cleaning chemistries, it is desirable to produce high concentrations of reactive atomic halogen species, such as atomic fluorine, etc.
According to one embodiment, the thermal insulator 140 comprises an erosion resistant thermal insulator. In one embodiment, the entire thermal insulator is made from the erosion resistant material. Alternatively, only a portion of the thermal insulator 140 , such as portions exposed to halogen-containing gas, can include the erosion resistant material. For example, the erosion resistant material may be included only at a peripheral exposed edge of the thermal insulator, while the remaining region of the thermal insulator includes a different material composition selected for providing a desired heat transfer co-efficient.
The erosion resistant thermal insulator can include an acryl-type material, such as an acrylic-based material or an acrylate-based material. Acrylic-based materials and acrylate-based materials can be formed by polymerizing acrylic or methylacrylic acids through a reaction with a suitable catalyst. Table 1 provides data illustrating the dependence of erosion resistance on material composition. For example, data is provided for silicon-containing adhesives, and a series of acrylic/acrylate-containing adhesives (prepared by various vendors X, Y, Z, Q, R & T). The data includes the erosion amount (mm 3 ) as a function of plasma (or RF power on) hours (hr); i.e, mm 3 /hr. As shown in Table 1, the acrylic/acrylate-containing adhesives exhibit more than an order of magnitude less erosion when subjected to a cleaning plasma (such as a SF 6 -based plasma).
TABLE 1
Silicon
Acryl type
type
X
Y
Z
Q
R
T
Thickness (mm)
0.13
0.13
0.25
0.13
0.15
0.05
0.12
Thermal conductivity (W/m-K)
0.25
0.35
0.6
0.37
0.3
0.6
0.2
Thermal resistance (E −4 )
5.2
3.7
4.2
3.5
7.5
8.3
6
Erosion ratio (mm 3 /hr)
5.5
0.32
0.3
0.22
0.25
0.15
0
According to yet another embodiment, the thermal insulator 140 comprises a non-uniform spatial variation of the heat transfer coefficient (W/m 2 −K) through the thermal insulator 140 between the temperature controlled support base 120 and the substrate support 130 . For example, the heat transfer coefficient can vary in a radial direction between a substantially central region of the thermal insulator 140 (below substrate 110 ) and a substantially edge region of the thermal insulator 140 (below substrate 110 ). The spatial variation of the heat transfer coefficient may comprise a non-uniform spatial variation of the thermal conductivity (W/m−K) of the thermal insulator 140 , or the spatial variation of the heat transfer coefficient may comprise a non-uniform spatial variation of the thickness of the thermal insulator 140 , or both. As used herein, the term “non-uniform spatial variation” of a parameter means a spatial variation of the parameter across an area of the substrate holder that is caused by design rather than inherent minor variations of the parameter across a substrate holder. Further, the term “substantially central region of the thermal insulator” means a region of the thermal insulator that would overlap a center of the substrate if placed on the substrate holder, and the term “substantially edge region of the thermal insulator” means a region of the thermal insulator that would overlap an edge of the substrate if placed on the substrate holder.
As illustrated in FIG. 2B , the thermal conductivity can vary in a radial direction between a substantially central region of the thermal insulator 140 below substrate 110 and a substantially edge region of the thermal insulator 140 below substrate 110 . For example, the thermal conductivity can vary between a first value between approximately 0.2 W/m−K and approximately 0.8 W/m−K and a second value between approximately 0.2 W/m−K and approximately 0.8 W/m−K. Additionally, for example, the thermal conductivity can be approximately 0.2 W/m−K near a substantially central region of the thermal insulator 140 and the thermal conductivity can be approximately 0.8 W/m−K near a substantially edge region of the thermal insulator 140 . Additionally yet, for example, the variation in the thermal conductivity substantially occurs between approximately the mid-radius region of the thermal insulator 140 and a substantially peripheral region of the thermal insulator 140 . As shown in FIG. 2B , the temperature may vary from center to edge between a first temperature (T 1 ) and a second temperature (T 2 ). Such variations in thermal conductivity (and temperature) may be imposed to counter excessive heating of the peripheral edge of the substrate by, for instance, the focus ring surrounding the substrate.
As illustrated in FIG. 3 , a substrate holder is described according to another embodiment. The substrate holder 200 comprises a substrate support 230 having a first temperature and configured to support a substrate 210 , a temperature-controlled support base 220 positioned below substrate support 230 and configured to be at a second temperature less than the first temperature (e.g. less than a desired temperature of substrate 210 ), and a thermal insulator 240 disposed between the substrate support 230 and the temperature-controlled support base 220 . Additionally, the substrate support 230 comprises one or more heating elements coupled thereto (not shown), and configured to elevate the temperature of the substrate support 230 (e.g. to heat the substrate). The thermal insulator 240 comprises a non-uniform thickness.
As shown, the thickness is less at a substantially center region of the thermal insulator 240 (below substrate 210 ) and it is relatively thicker at a substantially edge region below the substrate 210 . Alternatively, the thickness can be greater at a substantially center region below substrate 210 and it can be relatively thinner at a substantially edge region of substrate 210 . The non-uniform thickness of thermal insulator 240 may be imposed by a non-flat upper surface on support base 220 , or it may be imposed by a non-flat lower surface of substrate support 240 , or it may be imposed by a combination thereof. Alternatively yet, a layer of material having a different thermal conductivity than that of the thermal insulator 240 may be disposed on a portion of either the upper surface of support base 220 or the lower surface of substrate support 230 . For instance, a layer of Kapton®, Vespel®, Teflon®, etc., may be disposed on a substantially central region below substrate 210 , or such a layer may be disposed on a substantially peripheral region below substrate 210 .
Referring now to FIG. 4 , a substrate holder is described according to another embodiment. The substrate holder 300 comprises a substrate support 330 having a first temperature and configured to support a substrate 310 , a temperature-controlled support base 320 positioned below substrate support 330 and configured to be at a second temperature less than the first temperature (e.g. less than a desired temperature of substrate 310 ), and a thermal insulator 340 disposed between the substrate support 330 and the temperature-controlled support base 320 . Additionally, the substrate support 330 comprises one or more heating elements coupled thereto (not shown), and configured to elevate the temperature of the substrate support 330 .
As shown in FIG. 4 , the support base 320 comprises a plurality of protrusions, or ridges 342 , that partially extend into (or fully extend through) the thermal insulator 340 . Furthermore, the number density of protrusions can vary between a substantially central region 344 and a substantially peripheral region 346 of the substrate holder. For example, a higher density of protrusions may be placed at the peripheral region 346 , while a relatively lower density of protrusions may be placed at the central region 344 . Alternatively, for example, a lower density of protrusions may be placed at the peripheral region 346 , while a relatively higher density of protrusions may be placed at the central region 344 . In addition to the variation in density of protrusions, or in lieu of a variation in density, the size or shape or both of the protrusions may be varied.
The temperature controlled support base 120 ( 220 , 320 ) may be fabricated from a metallic material or a non-metallic material. For example, the support base 120 ( 220 , 320 ) can be fabricated from aluminum. Additionally, for example, the support base 120 ( 220 , 320 ) can be formed of a material having a relatively high thermal conductivity, such that the temperature of the support base can be maintained at a relatively constant temperature. The temperature of the temperature controlled support base is preferably actively controlled by one or more temperature control elements such as cooling elements. However, the temperature controlled support may provide passive cooling by use of cooling fins to promote enhanced free convection due to the increased surface area with the surrounding environment for example. The support base 120 ( 220 , 320 ) can further include passages therethrough (not shown) to permit the coupling of electrical power to the one or more heating elements of the substrate support, the coupling of electrical power to an electrostatic clamping electrode, the pneumatic coupling of heat transfer gas to the backside of the substrate, etc.
The substrate support 130 ( 230 , 330 ) may be fabricated from a metallic material or a non-metallic material. The substrate support 130 ( 230 , 330 ) can be fabricated from a non-electrically conductive material, such as a ceramic. For example, substrate support 130 ( 230 , 330 ) can be fabricated from alumina.
According to one embodiment, the one or more heating elements are embedded within the substrate support 130 ( 230 , 330 ). The one or more heating elements can be positioned between two ceramic pieces which are sintered together to form a monolithic piece. Alternatively, a first layer of ceramic is thermally sprayed onto the thermal insulator, followed by thermally spraying the one or more heating elements onto the first ceramic layer, and followed by thermally spraying a second ceramic layer over the one or more heating elements. Using similar techniques, other electrodes, or metal layers, may be inserted within the substrate support 130 ( 230 , 330 ). For example, an electrostatic clamping electrode may be inserted between ceramic layers and formed via sintering or spraying techniques as described above. The one or more heating elements and the electrostatic clamping electrode may be in the same plane or in separate planes, and may be implemented as separate electrodes or implemented as the same physical electrode.
Referring now to FIG. 5 , a substrate holder is described according to another embodiment. The substrate holder 400 comprises a substrate support 430 having a first temperature and configured to support a substrate 410 , a temperature-controlled support base 420 positioned below substrate support 430 and configured to be at a second temperature less than the first temperature (e.g. less than a desired temperature of substrate 410 ), and a thermal insulator 440 disposed between the substrate support 430 and the temperature-controlled support base 420 . Additionally, the substrate support 430 comprises one or more heating elements 431 coupled thereto, and configured to elevate the temperature of the substrate support 430 . Furthermore, the support base 420 comprises one or more cooling elements 421 coupled thereto, and configured to reduce the temperature of the substrate support 430 via the removal of heat from the substrate support 430 through thermal insulator 440 .
The one or more heating elements 431 can comprise at least one of a heating fluid channel, a resistive heating element, or a thermo-electric element biased to transfer heat towards the wafer. Furthermore, as shown in FIG. 5 , the one or more heating elements 431 are coupled to a heating element control unit 432 . Heating element control unit 432 is configured to provide either dependent or independent control of each heating element, and exchange information with a controller 450 .
For example, the one or more heating elements 431 can comprise one or more heating channels that can permit a flow rate of a fluid, such as water, Fluorinert, Galden HT-135, etc., therethrough in order to provide conductive-convective heating, wherein the fluid temperature has been elevated via a heat exchanger. The fluid flow rate and fluid temperature can, for example, be set, monitored, adjusted, and controlled by the heating element control unit 432 .
Alternatively, for example, the one or more heating elements 431 can comprise one or more resistive heating elements such as a tungsten, nickel-chromium alloy, aluminum-iron alloy, aluminum nitride, etc., filament. Examples of commercially available materials to fabricate resistive heating elements include Kanthal, Nikrothal, Akrothal, which are registered trademark names for metal alloys produced by Kanthal Corporation of Bethel, Conn. The Kanthal family includes ferritic alloys (FeCrAl) and the Nikrothal family includes austenitic alloys (NiCr, NiCrFe). For example, the heating elements can comprise a cast-in heater commercially available from Watlow (1310 Kingsland Dr., Batavia, Ill., 60510) capable of a maximum operating temperature of 400 to 450 C, or a film heater comprising aluminum nitride materials that is also commercially available from Watlow and capable of operating temperatures as high as 300 C and power densities of up to 23.25 W/cm 2 . Additionally, for example, the heating element can comprise a silicone rubber heater (1.0 mm thick) capable of 1400 W (or power density of 5 W/in 2 ). When an electrical current flows through the filament, power is dissipated as heat, and, therefore, the heating element control unit 432 can, for example, comprise a controllable DC power supply. A further heater option, suitable for lower temperatures and power densities, are Kapton heaters, consisted of a filament embedded in a Kapton (e.g. polyimide) sheet, marketed by Minco, Inc., of Minneapolis, Minn.
Alternately, for example, the one or more heating elements 431 can comprise an array of thermo-electric elements capable of heating or cooling a substrate depending upon the direction of electrical current flow through the respective elements. Thus, while the elements 431 are referred to as “heating elements,” these elements may include the capability of cooling in order to provide rapid transition between temperatures. Further, heating and cooling functions may be provided by separate elements within the substrate support 430 . An exemplary thermo-electric element is one commercially available from Advanced Thermoelectric, Model ST-127-1.4-8.5M (a 40 mm by 40 mm by 3.4 mm thermo-electric device capable of a maximum heat transfer power of 72 W). Therefore, the heating element control unit 432 can, for example, comprise a controllable current source.
The one or more cooling elements 421 can comprise at least one of a cooling channel, or a thermo-electric element. Furthermore, as shown in FIG. 5 , the one or more cooling elements 421 are coupled to a cooling element control unit 422 . Cooling element control unit 422 is configured to provide either dependent or independent control of each cooling element 421 , and exchange information with controller 450 .
For example, the one or more cooling elements 421 can comprise one or more cooling channels that can permit a flow rate of a fluid, such as water, Fluorinert, Galden HT-135, etc., therethrough in order to provide conductive-convective cooling, wherein the fluid temperature has been lowered via a heat exchanger. The fluid flow rate and fluid temperature can, for example, be set, monitored, adjusted, and controlled by the cooling element control unit 422 . Alternately, during heating for example, the fluid temperature of the fluid flow through the one or more cooling elements 421 may be increased to complement the heating by the one or more heating elements 431 . Alternately yet, during cooling for example, the fluid temperature of the fluid flow through the one or more cooling elements 421 may be decreased.
Alternately, for example, the one or more cooling elements 421 can comprise an array of thermo-electric elements capable of heating or cooling a substrate depending upon the direction of electrical current flow through the respective elements. Thus, while the elements 421 are referred to as “cooling elements,” these elements may include the capability of heating in order to provide rapid transition between temperatures. Further, heating and cooling function may be provided by separate elements within the temperature controlled support base 420 . An exemplary thermo-electric element is one commercially available from Advanced Thermoelectric, Model ST-127-1.4-8.5M (a 40 mm by 40 mm by 3.4 mm thermo-electric device capable of a maximum heat transfer power of 72 W). Therefore, the cooling element control unit 422 can, for example, comprise a controllable current source.
Additionally, as shown in FIG. 5 , the substrate holder 400 can further comprise an electrostatic clamp (ESC) comprising one or more clamping electrodes 435 embedded within substrate support 430 . The ESC further comprises a high-voltage (HV) DC voltage supply 434 coupled to the clamping electrodes 435 via an electrical connection. The design and implementation of such a clamp is well known to those skilled in the art of electrostatic clamping systems. Furthermore, the HV DC voltage supply 434 is coupled to controller 450 and is configured to exchange information with controller 450 .
Furthermore, as shown in FIG. 5 , the substrate holder 400 can further comprise a back-side gas supply system 436 for supplying a heat transfer gas, such as an inert gas including helium, argon, xenon, krypton, a process gas, or other gas including oxygen, nitrogen, or hydrogen, to the backside of substrate 410 through at least one gas supply line, and at least one of a plurality of orifices and channels (not shown). The backside gas supply system 436 can, for example, be a multi-zone supply system such as a two-zone (center/edge) system, or a three-zone (center/mid-radius/edge), wherein the backside pressure can be varied in a radial direction from the center to edge. Furthermore, the backside gas supply system 436 is coupled to controller 450 and is configured to exchange information with controller 450 .
Further yet, as shown in FIG. 5 , the substrate holder 400 can further comprise one or more temperature sensors 462 coupled to a temperature monitoring system 460 . The one or more temperature sensors 462 can be configured to measure the temperature of substrate 410 , or the one or more temperature sensors 462 can be configured to measure the temperature of substrate support 430 , or both. For example, the one or more temperature sensors 410 may be positioned such that the temperature is measured at the lower surface of the substrate support 430 as shown in FIG. 5 , or positioned such that the temperature of a bottom of the substrate 410 is measured.
The temperature sensor can include an optical fiber thermometer, an optical pyrometer, a band-edge temperature measurement system as described in pending U.S. patent application Ser. No. 10/168,544, filed on Jul. 2, 2002, the contents of which are incorporated herein by reference in their entirety, or a thermocouple (as indicated by the dashed line) such as a K-type thermocouple. Examples of optical thermometers include: an optical fiber thermometer commercially available from Advanced Energies, Inc., Model No. OR2000F; an optical fiber thermometer commercially available from Luxtron Corporation, Model No. M600; or an optical fiber thermometer commercially available from Takaoka Electric Mfg., Model No. FT-1420.
The temperature monitoring system 460 can provide sensor information to controller 450 in order to adjust at least one of a heating element, a cooling element, a backside gas supply system, or an HV DC voltage supply for an ESC either before, during, or after processing.
Controller 450 includes a microprocessor, memory, and a digital I/O port (potentially including D/A and/or ND converters) capable of generating control voltages sufficient to communicate and activate inputs to substrate holder 400 as well as monitor outputs from substrate holder 400 . As shown in FIG. 5 , controller 450 can be coupled to and exchange information with heating element control unit 432 , cooling element control unit 422 , HV DC voltage supply 434 , backside gas supply system 436 , and temperature monitoring system 460 . A program stored in the memory is utilized to interact with the aforementioned components of substrate holder 400 according to a stored process recipe. One example of controller 450 is a DELL PRECISION WORKSTATION 640™, available from Dell Corporation, Austin, Tex.
The controller 450 may also be implemented as a general purpose computer, processor, digital signal processor, etc., which causes a substrate holder to perform a portion or all of the processing steps of the invention in response to the controller 450 executing one or more sequences of one or more instructions contained in a computer readable medium. The computer readable medium or memory is configured to hold instructions programmed according to the teachings of the invention and can contain data structures, tables, records, or other data described herein. Examples of computer readable media are compact discs, hard disks, floppy disks, tape, magneto-optical disks, PROMs (EPROM, EEPROM, flash EPROM), DRAM, SRAM, SDRAM, or any other magnetic medium, compact discs (e.g., CD-ROM), or any other optical medium, punch cards, paper tape, or other physical medium with patterns of holes, a carrier wave, or any other medium from which a computer can read.
Controller 450 may be locally located relative to the substrate holder 400 , or it may be remotely located relative to the substrate holder 400 via an internet or intranet. Thus, controller 450 can exchange data with the substrate holder 400 using at least one of a direct connection, an intranet, or the internet. Controller 450 may be coupled to an intranet at a customer site (i.e., a device maker, etc.), or coupled to an intranet at a vendor site (i.e., an equipment manufacturer). Furthermore, another computer (i.e., controller, server, etc.) can access controller 450 to exchange data via at least one of a direct connection, an intranet, or the internet.
Optionally, substrate holder 400 can include an electrode through which RF power is coupled to plasma in a processing region above substrate 410 . For example, support base 420 can be electrically biased at an RF voltage via the transmission of RF power from an RF generator through an impedance match network to substrate holder 400 . The RF bias can serve to heat electrons to form and maintain plasma, or bias substrate 410 in order to control ion energy incident on substrate 410 , or both. In this configuration, the system can operate as a reactive ion etch (RIE) reactor, where the chamber and upper gas injection electrode serve as ground surfaces. A typical frequency for the RF bias can range from 1 MHz to 100 MHz and is preferably 13.56 MHz.
Alternately, RF power can be applied to the substrate holder electrode at multiple frequencies. Furthermore, an impedance match network can serve to maximize the transfer of RF power to plasma in the processing chamber by minimizing the reflected power. Various match network topologies (e.g., L-type, TC-type, T-type, etc.) and automatic control methods can be utilized.
Referring now to FIG. 6 , a substrate holder is described according to another embodiment. The substrate holder 500 comprises a substrate support 530 having a first temperature and configured to support a substrate 510 , a temperature-controlled support base 520 positioned below substrate support 530 and configured to be at a second temperature less than the first temperature (e.g. less than a desired temperature of substrate 510 ), and a thermal insulator 540 disposed between the substrate support 530 and the temperature-controlled support base 520 . Additionally, the substrate support 530 comprises a center heating element 533 (located at a substantially center region below substrate 510 ) and an edge heating element 531 (located at a substantially edge, or peripheral, region below substrate 510 ) coupled thereto, and configured to elevate the temperature of the substrate support 530 . Furthermore, the support base 520 comprises one or more cooling elements 521 coupled thereto, and configured to reduce the temperature of the substrate support 530 via the removal of heat from the substrate support 530 through thermal insulator 540 .
As shown in FIG. 6 , the center heating element 533 and the edge heating element 531 are coupled to a heating element control unit 532 . Heating element control unit 532 is configured to provide either dependent or independent control of each heating element, and exchange information with a controller 550 .
Additionally, as shown in FIG. 6 , the substrate holder 500 can further comprise an electrostatic clamp (ESC) comprising one or more clamping electrodes 535 embedded within substrate support 530 . The ESC further comprises a high-voltage (HV) DC voltage supply 534 coupled to the clamping electrodes 535 via an electrical connection. The design and implementation of such a clamp is well known to those skilled in the art of electrostatic clamping systems. Furthermore, the HV DC voltage supply 534 is coupled to controller 550 and is configured to exchange information with controller 550 .
Furthermore, as shown in FIG. 6 , the substrate holder 500 can further comprise a back-side gas supply system 536 for supplying a heat transfer gas, such as an inert gas including helium, argon, xenon, krypton, a process gas, or other gas including oxygen, nitrogen, or hydrogen, to the center region and the edge region of the backside of substrate 510 through two gas supply lines, and at least two of a plurality of orifices and channels (not shown). The backside gas supply system 536 , as shown, comprises a two-zone (center/edge) system, wherein the backside pressure can be varied in a radial direction from the center to edge. Furthermore, the backside gas supply system 536 is coupled to controller 550 and is configured to exchange information with controller 550 .
Further yet, as shown in FIG. 6 , the substrate holder 500 further comprises a center temperature sensor 562 for measuring a temperature at a substantially center region below substrate 510 and an edge temperature sensor 564 for measuring a temperature at a substantially edge region below substrate 510 . The center and edge temperature sensors 562 , 564 are coupled to a temperature monitoring system 560 .
Referring now to FIG. 8 , a flowchart describing a method 700 of controlling the temperature of a substrate on a substrate holder in a processing system is presented according to another embodiment. For example, the temperature control scheme can pertain to multiple process steps for a process in a processing system having a substrate holder such as one of those described in FIGS. 1 through 6 . The method 700 begins in 710 with disposing a substrate on a substrate holder.
The substrate holder comprises a plurality of temperature sensors reporting at least a temperature at an inner region and an outer region of the substrate and/or substrate holder. Additionally, the substrate holder comprises a substrate support having a first heating element and a second heating element heating the inner region and the outer region respectively, and a support base having a cooling element for cooling the inner region and the outer region. The first and second heating elements and the cooling element are controlled by a temperature control system to maintain the substrate holder at a selectable set-point temperature. Furthermore, the substrate holder comprises a thermal insulator disposed between the substrate support and the support base.
In 720 , the substrate is set to a first temperature profile. Using the temperature control system, a first base temperature for the base support (that is less than the first temperature profile (e.g. the substrate temperature), and a first inner set-point temperature and a first outer set-point temperature are selected. Thereafter, the temperature control system adjusts the cooling element and the first and second heating elements to achieve the selected temperatures described above.
In 730 , the substrate is set to a second temperature profile. Using the temperature control system, a second base temperature for the base support, and a second inner set-point temperature and a second outer set-point temperature are selected. Thereafter, the temperature control system changes the substrate temperature from the first temperature profile (i.e., first inner and outer set-point temperatures) to the second temperature profile (i.e., second inner and outer set-point temperatures) by optionally adjusting the cooling element to change the first base temperature to the second base temperature and adjusting the inner and outer heating elements until the second inner and outer set-point temperatures are achieved.
In one example, the substrate temperature is increased (or decreased) from the first temperature profile to the second temperature profile, while the second base temperature remains the same as the first base temperature. The power delivered to the inner and outer heating elements is increased (or decreased) in order to heat (or cool) the substrate from the first temperature profile to the second temperature profile.
In another example, the substrate temperature is increased (or decreased) from the first temperature profile to the second temperature profile, while the second base temperature is changed to a value different from the first base temperature. The power delivered to the inner and outer heating elements is increased (or decreased) in order to heat (or cool) the substrate from the first temperature profile to the second temperature profile, while the power delivered to the cooling element is increased (or decreased) in order to change the first base temperature to the second base temperature. Thus, according to one embodiment of the invention, the temperature of the support base is varied to assist the substrate support in controlling the temperature of the substrate. The present inventors have recognized that this varying of the support base temperature can provide more accurate and/or rapid temperature transitions of the substrate.
The temperature control system utilizes a control algorithm in order to stably adjust temperature(s) in response to measured values provided by the temperature monitoring system. The control algorithm can, for example, include a PID (proportional, integral and derivative) controller. In a PID controller, the transfer function in the s-domain (i.e., Laplacian space) can be expressed as:
G o ( s )= K P +K D s+K I s −1 , (1)
where K P , K D , and K I are constants, referred to herein as a set of PID parameters. The design challenge for the control algorithm is to select the set of PID parameters to achieve the desired performance of the temperature control system.
Referring to FIG. 7A , several exemplary time traces of temperature are shown to illustrate how different sets of PID parameters lead to a different temperature response. In each case, the temperature is increased from a first value to a second value. A first time trace of temperature 601 illustrates a relatively aggressive control scheme having a relatively low value for K I , for example, wherein the time trace exhibits “overshoot” and a series of oscillations following the overshoot. A second time trace of temperature 602 illustrates a relatively less aggressive control scheme having a relatively higher value for K I , for example, wherein the time trace exhibits a relatively slow, gradual increase to the second temperature. A third time trace of temperature 603 illustrates a desired moderately aggressive control scheme having a value for K I between that of time trace 601 and time trace 602 , for example, wherein the time trace exhibits a relatively faster increase to the second temperature without overshoot. However, the present inventors have recognized that the use of only one PID parameter set is not sufficient to provide a desired condition for stability and rise rate.
According to one embodiment, two or more PID parameter sets are utilized to achieve a rapid and stable adjustment of the temperature between an initial value and a final value. FIG. 7B illustrates an exemplary time trace of temperature 600 utilizing two sets of PID parameters. A first set of PID parameters is used for a first time duration 622 , and a second set of PID parameters is used for a second time duration 624 . The first time duration 622 can be determined by setting a temperature offset 620 from the final value of the temperature. For example, the temperature offset can range from approximately 50% to 99% of the temperature difference between the initial value and the final value. Additionally, for example, the temperature offset can range from approximately 70% to 95% of the temperature difference between the initial value and the final value, and desirably, the temperature offset can range from approximately 80% to 95%.
For example, a relatively aggressive PID parameter set may be used for the first time duration 622 , while a relatively less aggressive PID parameter set may be used for the second time duration 624 . Alternatively, for example, the PID parameter K D can be increased from the first PID set to the second PID set, the PID parameter K I can be decreased from the first PID set to the second PID set, or a combination thereof.
Although only certain embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.
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A method for multi-step temperature control of a substrate includes selecting a first set-point temperature and a second set-point temperature for the substrate, and selecting a first PID parameter set including a first proportional constant K P1 , a first integral constant K I1 and a first derivative constant K D1 , and selecting a second PID parameter set including a second proportional constant K P2 , a second integral constant K I2 and a second derivative constant K D2 . The substrate is placed on a substrate holder, the temperature of the substrate is adjusted to the first set-point temperature and the substrate is processed for a first period of time at the first set-point temperature. The temperature of a region of the substrate is changed from the first set-point temperature to the second set-point temperature using the first PID parameter set for a first ramp period of time and using the second PID parameter set for a second ramp period of time, the second ramp period of time following the first ramp period of time. The substrate is then processed for a second period of time at the second set-point temperature.
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CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to lift gates for sport utility vehicles (SUVs) and the like. More particularly, the present invention relates to a lift gate extender for SUVs, vans, and similar vehicles that employ a lift gate.
[0004] The evolution of the motor vehicle has persisted over the last one hundred years, commencing with the so-called “horseless carriage” to Model T pickup trucks in short order. Since that time numerous utility type vehicles have been offered by the automotive manufacturers such that in recent decades there has been a convergence on certain types of designs.
[0005] One of the more prolific design features that has gained favor has been the liftgate which allows a user of a motor vehicle to access the rear compartment areas. In the case of pickup truck, the liftgate can be seen in use with truck caps that typically cover the pickup bed and provide an enhanced enclosed area. Where the truck cap meets the tailgate at the rear of the pickup truck, a liftgate is provided to allow the user to gain access to the enclosed area without the need for completely opening up the tailgate and then climbing into the rear of the truck.
[0006] The liftgate was also deployed on the very popular mini-vans and then on the SUVs. In the case of the mini-van the liftgate is used without the benefit of a true tailgate in most instances. The liftgate is elongated and is hinged near the roofline of the mini-van and results in a very large door that swings upwardly to allow access to the rear compartment area of the vehicle. In the case of the SUV, most designs seem to favor the combination tailgate and liftgate features which reduces the size of the liftgate to a modest assembly that can easily be handled. Nonetheless the liftgate shares the upward movement about a hinged top that is seen with the mini-vans although the user clearance is much reduced since the overall size of the liftgate is less than half that of the one used on the mini-van.
[0007] As one would expect, the existence of substantial cargo space at the rear of a vehicle is a highly attractive feature. Whether it is a pickup truck, mini-van or an SUV, the desirability of such vehicles lies in the occasional need for carrying a cargo. When this happens, users are sometimes confronted with situation that exceed the capacity or frustrate the capability of the particular vehicle. Sometimes this is due to the size of the cargo, such as those cases where it extends beyond the liftgate/tailgate of the vehicle, or in other case it arises from the nature of the cargo, such as pets like dogs, which need to have access to fresh air and ventilation. It happens therefore that a long-standing problem has arisen from such situations where the liftgate is not adequate to deal with the user's desires and objectives.
[0008] The problems associated with the typical liftgate design commence from the fact that once the liftgate is opened, even if for a little bit, security of the contents of the vehicle is compromised. In the case of materials and possessions, these are exposed to public generally and to criminals more specifically. In the case of pets like dogs, the choice between a closed or open liftgate is a real dilemma. If left open, the pet is able to jump out of the vehicle, or to be stolen by a passer-by. If the liftgate is left close, the pet does not have ventilation which as most people are aware, can be deadly to an animal left in a motor vehicle. Thus the user or owner of the pickup truck, mini-van or SUV is left with some difficult choices and issues.
[0009] It is an object of the present invention to allow for a liftgate extender that can securely hold a liftgate at a partially open position.
[0010] It is also another object of the present invention to allow for a liftgate extender that is compatible with the lock mechanism of the subject vehicle.
[0011] It is also a further object of the present invention to allow for a liftgate extender that is simple to use.
[0012] Lastly, it is an object of the present invention to provide for a liftgate extender that is comprised of a few parts and is very economical to purchase and use.
[0013] These and other objects and attributes of the present invention will be disclosed and discussed in more detail within this application.
SUMMARY OF THE INVENTION
[0014] A liftgate extender for use in conjunction with a liftgate on a motor vehicle is comprised of a tubular member with a slot end and a hook end, where the hook end compatibly engages the hasp of the liftgate mechanism and where the slot end compatibly engages the latch of a lock mechanism provided with the liftgate and is lockable. The hook end of the liftgate extender further includes a threaded portion that is threaded into the tubular member and which is adjustable over a range of longitudinal adjustments. The hook end engages the hasp of the liftgate mechanism and is sized to ground out on the hasp base before allowing the hasp to become freed from the hook portion of the hook end.
[0015] The liftgate extender of the present invention further includes a preferred length whereby the distance of the opening provided by the extender between the liftgate sill and the edge of the liftgate is approximately eight inches in length.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a partial isometric view of an SUV showing an example of a liftgate of the type used in conjunction with the present invention.
[0017] FIG. 2 is an exploded isometric view of a lock assembly of the type commonly used in liftgate mechanisms and which is used in conjunction with the present invention.
[0018] FIG. 3 is an elevational view of the lock assembly of FIG. 2 , where it is shown in oriented with respect to the hasp (or the hook) which is engaged with the striker of the lock assembly.
[0019] FIG. 4 is an isometric view of the extender of the present invention.
[0020] FIG. 5 is an elevational view of the extender of FIG. 4 , where the hook end is engaged with the hasp of a liftgate (in phantom) and the slot end is engaged with the latch of a lock assembly of a liftgate (shown in phantom).
[0021] FIG. 6 is an elevational view of the hook end of the extender of FIG. 4 engaging a hasp of a liftgate.
[0022] FIG. 7 is an elevational view of the slot end of the extender of FIG. 4 engaging a latch of a lock assembly of a liftgate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The popularity of SUVs and similar types of vehicles with liftgate type features has increased steadily over the past two decades. Part of this appeal comes from the fact that the vehicles offer the functionality of a passenger vehicle along with the utility of a work vehicle. The types of vehicles that employ liftgates, as mentioned above, include minivans and pickup trucks with caps, typically provide the user with dual purposes where they carry passengers and/or cargos depending on the user's requirements, thus the extender is very helpful in providing the secured openings needed for the carriage of pets or the retention of cargo in such applications. The extender of the present invention is also useful for retaining loads in the trunk compartments of the typical passenger vehicle as well. In this case the extender is used in between the trunk lid latch and the corresponding point on the vehicle body. While the usage of the invention in this manner may not necessarily be dedicated to the carriage of pets, the extender is particularly useful for the retention of cargo held in the trunk when the cargo is too large to allow the trunk lid to be closed. For the purposes of this application, the references to the SUV will be understood to encompass any application where a liftgate or similar gate or trunk lid is used in a motor vehicle, inclusive of passenger vehicles.
[0024] Turning now to FIG. 1 , a typical SUV 10 is shown in a partial view with the tailgate 12 , the liftgate 14 , the handle 16 and the lock 18 . This design is very commonly used and virtually every motor vehicle manufacturer produces a product of this type. In this case the liftgate 14 operates when unlocked and lifts upwardly to provide access to the cargo area enclosed at the rear of the SUV 10 . This operation can occur independent from the tailgate 12 thus allowing the user to be able to reach in and load or unload cargo as desired.
[0025] A lock assembly 20 is disclosed in FIG. 2 and is of a type that is commonly used in liftgate applications. The lock assembly 20 includes components that are pertinent to the use of the present invention and comprise the hasp 22 , the latch 24 and the striker 26 . In the drawing, the hasp 22 is shown in orientation to be fitted into the striker 26 where as will be understood more clearly below, the latch 26 can be rotated to engage the hasp 22 .
[0026] Further details of the lock assembly 20 are seen in FIG. 3 where the lock 18 is shown installed in the lock assembly 20 . Also shown is the key 30 which is used to operate the lock 18 .
[0027] The extender 40 for use with a liftgate is shown in FIG. 4 and includes the slot 42 , the hook 44 , the tubular member 46 , the hook end 48 , the hook top 50 , the threads 52 and the slot end 54 . In FIG. 5 the extender 40 is shown in the installed condition where the latch 24 engages the slot 42 while at the same time the hook 44 is engaged with the hasp 22 . More specifically, FIGS. 6 and 7 reveal the engagement of the hook 44 with the hasp 22 and the slot end 54 with the latch 24 . From the drawings it can be seen that the hasp 22 is affixed to the hasp base 62 and that the latch 24 is located near the liftgate sill 60 .
[0028] The function of the extender of the present invention is to provide a support for the liftgate that will retain the liftgate in a partially opened position and which will at the same time retain the locking function of the liftgate. This is an important consideration in many different circumstances but it has been found to be especially useful when one has pets (dogs) riding in the cargo area of an SUV. With the use of the extender, the pets can have adequate ventilation without the fear that the liftgate will open all the way or that third persons could access the cargo area. The advisability of using the extender for ventilation purposes will need to be considered on a case-by-case basis such that if it is used when the vehicle is in motion, there must be sufficient confidence that the pet will not be able to get through the opening created. While this doesn't necessarily pose a problem based on applicant's uses of the device thus far, the consideration is prudent and a matter of common sense. The extender provides an adjustable range of openings between the liftgate sill and the liftgate to the user by screwing the hook into or out of the tubular member by means of the threaded portion of the hook. The tubular member is provided with a captured nut or a threaded receiving portion compatible with the threaded portion on the hook, in any manner which is well known in the art. A preferred range of openings is 6-10 inches, wherein 8 inches is especially useful for providing the ventilation requirements for an average sized dog without allowing too much clearance for the dog to exit the vehicle. In other uses the extender can be deployed when the user is carrying cargo that exceeds the length of the cargo area in the vehicle. For instance, if the user is transporting lengths of lumber or wood pieces that extend outward from the tailgate, the extender can be used to keep the liftgate in a defined and selected position while maintaining the locking function of the liftgate. The sizing of the tubular member and its threaded portion, the hook and the length of the slot end all combine to provide the desired range of openings which is a matter of an engineering selection.
[0029] As may be appreciated from the drawings, the extender utilizes the hasp and the latch of the existing tailgate assembly in the typical SUV. In particular the slot of the extender is sized to receive the latch of the lock assembly such that the lock and lock assembly function the same way as if the hasp is received by the striker. Thus there is no need to provide any auxiliary locking mechanism to supplement the extended; it works with the OEM locking system of the liftgate.
[0030] It is understood that the orientation of the hasp and latch may be modified from the orientation that is presented herein without departing from the functionality and benefits of the present invention. For instance, where the drawings indicate the lock assembly to be located in the liftgate sill and the hasp on the lower end on the liftgate, these locations can be reversed in some cases. The situation is case specific for each vehicle manufacturer although it is understood that the extender will work within such circumstances where the compatibility between the engagement of the hook portion and the slot portion of the extender and the hasp and the latch respectively still exists. In addition, the lock assembly shown is by way of example. There are other types of lock assemblies that can be used where the latch may vary somewhat, however so long as the latch is engageable with the slot end of the extender the present invention would be applicable.
[0031] The materials of choice for the fabrication of the extender are typically metals, and typically these are steel. The tubular member may a hollow tube where the slot end is worked to be flattened and to provide a slot. The other end is fabricated to include a compatible receiver for the threaded end of the hook such that the hook can be turned in and out from the tubular member thereby adjusting the overall length of the extender in accordance with the objectives of the user. The hook is fabricated from steel and is formed with a threaded end that is compatible with insertion and engagement with the tubular member.
[0032] In use, the hook is engaged with the hasp before the slot end is inserted into position for engagement with the latch. The engagement of the latch with the slot of the extender occurs when the key is rotated in the lock and the latch is rotated into an engaged position as may be understood from the drawings. The hook is sized such that when installed, the hook top grounds out on the hasp base before the hasp can reach the opening in the hook and be released. This means that the only way the extender can be removed from the installation is by unlocking the lock assembly which occurs when the latch is rotated back to an open and disengaged position, thereby allowing the slot end of the extender to be freed and removeable from the lock assembly.
[0033] The uses and applications of the present invention that have been discussed herein are meant by way of illustration and not by limitation. The extender may be successfully used on pickup truck caps, minivans and other liftgate type applications where the objectives for deploying an extender are indicated. Other variations in the type of hook, or slot end, or the selection of materials are possible and are not meant to be excluded from consideration.
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A novel extender for maintaining a liftgate or similar feature on a motor vehicle in a secured and fixed open position is disclosed. The extender of the present invention includes a tubular member with a slot end and a hook end for respectively engaging the latch and the hasp of a locking mechanism. The extender being fitted between the latch and hasp of the locking mechanism can be locked into place thereby defining a fixed open distance for the liftgate while being resistant to removal.
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CROSS-REFERENCE TO RELATED APPLICATION
None
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the control of oil and gas production wells. More particularly, it relates to control of movable elements in well production flow control devices.
2. Description of the Related Art
The control of oil and gas production wells constitutes an on-going concern of the petroleum industry due, in part, to the enormous monetary expense involved in addition to the risks associated with environmental and safety issues. Production well control has become particularly important and more complex in view of the industry wide recognition that wells having multiple branches (i.e., multilateral wells) will be increasingly important and commonplace. Such multilateral wells include discrete production zones which produce fluid in either common or discrete production tubing. In either case, there is a need for controlling zone production, isolating specific zones and otherwise monitoring each zone in a particular well. Flow control devices such as sliding sleeve valves, downhole safety valves, and downhole chokes are commonly used to control flow between the production tubing and the casing annulus. Such devices are used for zonal isolation, selective production, flow shut-off, commingling production, and transient testing.
It is desirable to operate the downhole flow control device with a variable flow control device. The variable control allows the valve to function in a choking mode which is desirable when attempting to commingle multiple producing zones that operate at different reservoir pressures. This choking prevents crossflow, via the wellbore, between downhole producing zones.
In the case of a hydraulically powered flow control device such as a sliding sleeve valve, the valve experiences several changes over time. For example, hydraulic fluid ages and exhibits reduced lubricity with exposure to high temperature. Scale and other deposits will occur in the interior of the valve. In addition, seals will degrade and wear with time. For a valve to act effectively as a choke, it needs a reasonably fine level of controllability. One difficulty in the accurate positioning of the moveable element in the flow control device is caused by fluid storage capacity of the hydraulic lines. Another difficulty arises from the fact that the pressure needed to initiate motion of the moveable element is different from the pressure needed to sustain motion, which is caused by the difference between static and dynamic friction coefficients, with the static coefficient being larger than the dynamic coefficient. When pressure is continuously applied through the hydraulic line, the elastic nature of the lines allows some expansion that, in effect, causes the line to act as a fluid accumulator. The longer the line the larger this effect. In operation, the combinations of these effects can cause substantial overshoot in the positioning of the moveable element. For example, if the hydraulic line pressure is raised to overcome the static friction, the sleeve starts to move. A known amount of fluid is commonly pumped into the system to move the element a known distance. However, because of the fluid storage effect of the hydraulic line and the lower force required to continue motion, the element continues to move past the desired position. This can result in undesirable flow restrictions.
The present invention overcomes the foregoing disadvantages of the prior art by providing a system and method for overcoming the static friction while substantially reducing the overshoot effect. Still other advantages over the prior art will be apparent to one skilled in the art.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a system for controlling a downhole flow control device that includes a flow control device at a downhole location in a well wherein the flow control device has a movable element for controlling a downhole formation flow. The movable element has a hydraulic seal associated therewith. The seal is constructed such that a maximum pressure of an applied pressure pulse is sufficient to overcome a static friction force associated with the seal, and wherein a minimum pressure of an applied pressure pulse is insufficient to overcome a dynamic friction force associated with the seal.
In another aspect, a method for controlling a flow control device includes transmitting a pressure pulse from a surface located hydraulic source to the flow control device at a downhole location. A characteristic of the pressure pulse is controlled to incrementally move a moveable element in the flow control device to a desired position. Exemplary controlled characteristic of the pressure pulse comprises pulse magnitude and pulse duration.
While the foregoing disclosure is directed to the preferred embodiments of the invention, various modifications will be apparent to those skilled in the art. It is intended that all variations within the scope of the appended claims be embraced disclosure. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set for the above are possible without departing from the scope and the spirit of the invention. It is intended that the following claims be interpreted to embrace all such modifications and changes.
BRIEF DESCRIPTION OF THE DRAWINGS
For detailed understanding of the present invention, reference should be made to the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein:
FIG. 1 is a schematic of a production well flow control system according to one embodiment of the present invention;
FIG. 2 is a graph showing continued motion of a moveable element in a flow control device due to the effects of static and dynamic friction; and,
FIG. 3 is a schematic of pulsed hydraulic pressure in relation to the pressure required to overcome static and dynamic friction and the related movement of a moveable element in a flow control device.
DETAILED DESCRIPTION OF THE INVENTION
As is known, a given well may be divided into a plurality of separate zones which are required to isolate specific areas of a well for purposes including, but not limited to, producing selected fluids, preventing blowouts, and preventing water intake.
With reference to FIG. 1 , well 1 includes two exemplary zones, namely zone A and zone B, where the zones are separated by an impermeable barrier. Each of zones A and B have been completed in a known manner. FIG. 1 shows the completion of zone A using packers 15 and sliding sleeve valve 20 supported on tubing string 10 in wellbore 5 . The packers 15 seal off the annulus between the wellbore and a flow control device, such as sliding sleeve valve 20 , thereby constraining formation fluid to flow only through open sliding sleeve valve 20 . Alternatively, the flow control device may be any flow control device having at least one moveable element for controlling flow, including, but not limited to, a downhole choke and a downhole safety valve. As is known in the art, a common sliding sleeve valve employs an outer housing with slots, also called openings, and an inner spool with slots. The slots are alignable and misalignable with axial movement of the inner spool relative to the outer housing. Such devices are commercially available. Tubing string 10 is connected at the surface to wellhead 35 .
In one embodiment, sliding sleeve valve 20 is controlled from the surface by two hydraulic control lines, opening line 25 and closing line 30 , that operate a balanced, dual acting, hydraulic piston (not shown) in the sliding sleeve 20 . The hydraulic piston shifts a moveable element, such as inner spool 22 , also called a sleeve, to align or misalign flow slots, or openings, allowing formation fluid to flow through sliding sleeve valve 20 . Multiple configurations of the moveable element are known in the art, and are not discussed in detail herein. Such a device is commercially available as HCM Hydraulic Sliding Sleeve from Baker Oil Tools, Houston, Texas. In operation, line 25 is pressurized to open the sliding sleeve valve 20 , and line 30 is pressurized to close the sliding sleeve valve 20 . During a pressurization of either line 25 or 30 , the opposite line may be controllably vented by valve manifold 65 to the surface reservoir tank 45 . The line 25 and 30 are connected to pump 40 and the return reservoir 45 through valve manifold 65 which is controlled by processor 60 . The pump 40 takes hydraulic fluid from reservoir 45 and supplies it under pressure to line 41 . Pressure sensor 50 monitors the pressure in pump discharge line 41 and provides a signal to processor 60 related to the detected pressure. The cycle rate or speed of pump 40 is monitored by pump cycle sensor 55 which sends an electrical signal to processor 60 related to the number pump cycles. The signals from sensors 55 and 50 may be any suitable type of signal, including, but not limited to, optical, electrical, pneumatic, and acoustic. By its design, a positive displacement pump discharges a determinable fluid volume for each pump cycle. By determining the number of pump cycles, the volume of fluid pumped can be determined and tracked. Valve manifold 65 acts to direct the pump output flow to the appropriate hydraulic line 25 or 30 to move spool 22 in valve 20 in an opening or closing direction, respectively, as directed by processor 60 . Processor 60 contains suitable interface circuits and processors, acting under programmed instructions, to provide power to and receive output signals from pressure sensor 50 and pump cycle sensor 55 ; to interface with and to control the actuation of manifold 65 and the cycle rate of pump 40 ; and to analyze the signals from the pump cycle sensor 55 and the pressure sensor 50 , 80 , 81 , and to issue commands to the pump 40 and the manifold 65 to control the position of the spool 22 in the sliding sleeve valve 20 between an open position and a closed position. The processor provides additional functions as described below.
In operation, sliding sleeve valve 20 is commonly operated so that the valve openings are placed in a fully open or fully closed condition. As previously noted, however, it is desirable to be able to proportionally actuate such a device to provide intermediate flow conditions that can be used to choke the flow of the reservoir fluid. Ideally, the pump could be operated to supply a known volume of fluid which would move spool 22 a determinable distance. However, the effects of static and dynamic friction associated with movable elements in the flow control device, such as the spool 22 , when combined with the fluid storage capacity of hydraulic lines 25 and 30 can cause significant overshoot in positioning of spool 22 . These effects can be seen in FIG. 2 , which shows the movement 103 of spool 22 as fluid is pumped to move spool 22 . Pump pressure builds up along curve 100 . In one embodiment, any pulsations caused by pump 40 are damped out by transmission through the supply line. Pressure is built up to pressure 101 to overcome the static friction of seals (not shown) in sliding sleeve valve 20 . In an ideal hydraulic system, once the spool 22 begins to move, the supply line pressure reduces to line 102 and additional fluid can be supplied at the lower pressure to move spool 22 to a desired position 108 . However, the entire hydraulic supply line 25 , 30 is pressured to the higher pressure 101 , and expansion of supply line 25 , 30 results in a significant volume of fluid at pressure 101 . Instead of the fluid pressure being at level 102 , it gradually is reduced along line 107 , forcing spool 22 to position 109 , and overshooting the desired position 108 .
To reduce the overshoot issue, see FIG. 3 , the present invention in one embodiment provides pressure pulses 203 that move spool 22 in incremental steps to the desired position. By using pulses 203 , the effects of supply line expansion are significantly reduced. Each pulse 203 is generated such that pulse peak pressure 207 exceeds the pressure 201 needed to overcome the static friction force resisting motion of spool 22 , and the pulse minimum pressure 208 is less than the pressure 202 required to overcome the force required to overcome the dynamic friction force resisting motion. In one embodiment, pressure pulses 203 are superimposed on a base pressure 205 . The motion 206 of spool 22 is essentially a stair step motion to reach the desired position 210 . While the spool 22 has been discussed, it should be understood that the spool 22 in only one illustrative movable element. Other movable elements and their associated static and dynamic frictions can also be utilized in the above-described manner.
As shown in FIG. 1 , in one embodiment, a pressure source 70 , which may be a hydraulic cylinder, is hydraulically coupled to line 49 via line 75 . Piston 71 is actuated by a hydraulic system 72 through line 73 that moves piston 71 in a predetermined manner to impress pulses 203 on line 41 . Such pulses are transmitted down supply lines 25 , 30 and cause incremental motion of spool 22 . Hydraulic system 72 may be controlled by processor 60 to alter maximum and minimum pulse pressure and pulse width W, also called pulse duration, to provide additional control of the incremental motion of spool 22 . Alternatively, pump 40 may be a positive displacement pump having sufficient capabilities to generate pulses 203 .
In one embodiment, the effects of the compliant supply lines 25 , 30 are accounted for by comparing signals form pressure sensor 50 , at the surface, to signals from pressure sensors 80 and 81 , located at the downhole location on supply lines 25 and 30 , respectively. Signals from sensors 80 and 81 are transmitted along signal lines (not shown) to processor 60 . The comparisons of such signals can be used to determine a transfer function F that relates the transmitted pressure pulse to the received pulse. Transfer function F may be programmed into processor 60 to control one or more characteristics of the generated pressure pulse, such as for example, pulse magnitude and pulse duration, such that the received pressure pulse is of a selected magnitude and duration to accurately position spool 22 at the desired position. As used herein, pulse magnitude is the difference between the maximum pulse pressure 207 and the minimum pulse pressure 208 . As used herein, pulse duration is the time in which the pressure pulse is able to actually move spool 22 .
In another embodiment, position sensor 83 is disposed in sliding sleeve valve 20 to determine the position of spool 22 within sliding sleeve valve 20 . Here, transfer function F′ may be determined by comparing the generated pulse to the actual motion of spool 22 . Position sensor 83 may be any suitable position sensing technique, such as, for example, the position sensing system described in U.S. patent application Ser. No. 10/289,714, filed on Nov. 7, 2002, and assigned to the assignee of the present application, and which is incorporated herein by reference for all purposes.
While the systems and methods are described above in reference to production wells, one skilled in the art will realize that the system and methods as described herein are equally applicable to the control of flow in injection wells. In addition, one skilled in the art will realize that the system and methods as described herein are equally applicable to land and seafloor wellhead locations.
The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible. It is intended that the following claims be interpreted to embrace all such modifications and changes.
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A system for controlling flow in a wellbore uses a downhole flow control device positioned at a downhole location in the wellbore. The flow control device has a movable element for controlling a downhole fluid flow. In response to an applied pressure pulse, the movable element moves in finite increments from one position to another. In one embodiment, a hydraulic source generates a transmitted pressure pulse to the flow control device wherein the maximum pressure of a received pressure pulse downhole is sufficient to overcome a static friction force associated with the movable element, and wherein a minimum pressure of the received pressure pulse downhole is insufficient to overcome a dynamic friction force associated with the movable element.
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[0001] This application claims the benefit of U.S. Provisional Application No. 60/290,504, filed May 11, 2001, which is herein incorporated by reference.
TECHNICAL FIELD OF INVENTION
[0002] The present invention relates to inhibitors of p38, a mammalian protein kinase involved in cell proliferation, cell death and response to extracellular stimuli. The invention also relates to methods for producing these inhibitors. The invention also provides pharmaceutical compositions comprising the inhibitors of the invention and methods of utilizing those compositions in the treatment and prevention of various disorders.
BACKGROUND OF THE INVENTION
[0003] Protein kinases are involved in various cellular responses to extracellular signals. Recently, a family of mitogen-activated protein kinases (MAPK) has been discovered. Members of this family are Ser/Thr kinases that activate their substrates by phosphorylation [B. Stein et al., Ann. Rep. Med. Chem., 31, pp. 289-98 (1996)]. MAPKs are themselves activated by a variety of signals including growth factors, cytokines, UV radiation, and stress-inducing agents.
[0004] One particularly interesting MAPK is p38. p38, also known as cytokine suppressive anti-inflammatory drug binding protein (CSBP) and RK, was isolated from murine pre-B cells that were transfected with the lipopolysaccharide (LPS) receptor, CD14, and induced with LPS. p38 has since been isolated and sequenced, as has the cDNA encoding it in humans and mouse. Activation of p38 has been observed in cells stimulated by stress, such as treatment of lipopolysaccharides (LPS), UV, anisomycin, or osmotic shock, and by cytokines, such as IL-1 and TNF.
[0005] Inhibition of p38 kinase leads to a blockade on the production of both IL-1 and TNF. IL-1 and TNF stimulate the production of other proinflammatory cytokines such as IL-6 and IL-8 and have been implicated in acute and chronic inflammatory diseases and in post-menopausal osteoporosis [R. B. Kimble et al., Endocrinol., 136, pp. 3054-61 (1995)].
[0006] Based upon this finding, it is believed that p38, along with other MAPKs, have a role in mediating cellular response to inflammatory stimuli, such as leukocyte accumulation, macrophage/monocyte activation, tissue resorption, fever, acute phase responses and neutrophilia. In addition, MAPKs, such as p38, have been implicated in cancer, thrombin-induced platelet aggregation, immunodeficiency disorders, autoimmune diseases, cell death, allergies, osteoporosis and neurodegenerative disorders. Inhibitors of p38 have also been implicated in the area of pain management through inhibition of prostaglandin endoperoxide synthase-2 induction. Other diseases associated with Il-1, IL-6, IL-8 or TNF overproduction are set forth in WO 96/21654.
[0007] Others have already begun trying to develop drugs that specifically inhibit MAPKs. For example, PCT publication WO 95/31451 describes pyrazole compounds that inhibit MAPKs, and, in particular, p38. However, the efficacy of these inhibitors in vivo is still being investigated.
[0008] Other p38 inhibitors have been produced, including those described in WO 98/27098, WO 99/00357, WO 99/10291, WO 99/58502, WO 99/64400, WO 00/17175 and WO 00/17204. In addition, WO 97/24328, WO 98/34920, WO 98/35958 and U.S. Pat. No. 5,145,857 disclose amino-substituted heterocycles having therapeutic uses. However, none of the disclosed therapeutic uses include inhibition of p38 or other serine/threonine protein kinases.
[0009] Accordingly, there is still a great need to develop other potent inhibitors of p38, including p38-specific inhibitors, that are useful in treating various conditions associated with p38 activation.
SUMMARY OF THE INVENTION
[0010] The present invention addresses this problem by providing compounds that demonstrate inhibition of p38.
[0011] These compounds have the general formulae:
[0012] or a pharmaceutically acceptable derivative thereof, wherein:
[0013] A is N or CR.
[0014] B is N or CR.
[0015] X is N or CH.
[0016] Y is C(O), CHOH, CH 2 , S, S(O), S(O) 2 , NH, NR, O or Z.
[0017] Z is CHOH, —[(C 2 -C 3 )-alkyl]-, —S—[(C 1 -C 3 )-alkyl]-, —O—[(C 1 -C 3 )-alkyl]-, —NH—[(C 1 -C 3 )—alkyl]-, —[(C 2 -C 3 )-alkenyl]-, —[(C 2 -C 3 )-alkynyl]-, —O—[(C 2 -C 3 )-alkenyl]-, —O—[(C 2 -C 3 )-alkynyl]-, —S—[(C 2 -C 3 )-alkenyl]-, —S—[(C 2 -C 3 )-alkynyl]-, —NH—[(C 2 -C 3 )—alkenyl]-, —NH—[(C 2 -C 3 )-alkynyl]-, —[(C 1 -C 3 )-alkyl]—S—, —[(C 1 -C 3 )-alkyl]-O—, —[(C 1 -C 3 )-alkyl]-NH—, —[(C 2 -C 3 )-alkenyl]-O—, —[(C 2 -C 3 )-alkynyl]-O—, —[(C 2 -C 3 )-alkenyl]-S—, —[(C 2 -C 3 )-alkynyl]-S—, —[(C 2 -C 3 )-alkenyl]-NH— or —[(C 2 -C 3 )-alkynyl]-NH—.
[0018] The carbon atoms of Q may be optionally substituted with R.
[0019] R 1 is selected from aryl, heteroaryl, carbocyclyl, heterocyclyl or C 1-10 aliphatic, any of which may be optionally substituted.
[0020] R 3 is selected from aryl, heteroaryl, carbocyclyl, heterocyclyl, or C 1-10 aliphatic, any of which may be optionally substituted.
[0021] R 4 is selected from NHR 5 , N(R 5 ) 2 , OR 5 , C(O)OR 5 , —C(O)R 5 or R 6 .
[0022] Each R 5 is independently selected from aryl, heteroaryl, carbocyclyl, heterocyclyl or C 1-5 aliphatic;
[0023] R 3 is selected from aryl, heteroaryl, carbocyclyl, heterocyclyl or C 1-5 aliphatic, any of which may be optionally substituted.
[0024] Each R is independently selected from H, halo or a straight or branched chain C 1 -C 4 alkyl.
[0025] Each of R 1 , R 5 and R 6 are independently and optionally substituted with up to 4 substituents, each of which is independently selected from halo; C 1 -C 3 alkyl optionally substituted with NR′ 2 , OR′, CO 2 R′ or CONR′ 2 ; O—(C 1 -C 3 )-alkyl optionally substituted with NR′ 2 , OR′, CO 2 R′ or CONR′ 2 ; NR′ 2 ; OCF 3 ; CF 3 ; NO 2 ; CO 2 R′; CONR′; SR′; COR′; S(O 2 )N(R′) 2 ; SCF 3 ; CN; N(R′)C(O)R′; N(R′)C(O)OR 1 ; N(R′)C(O)C(O)R′; N(R′)S(O 2 )R′; OR′; OC(O)R′; OP(O) 3 H 2 ; or N═C—N(R′) 2
[0026] R 3 is optionally substituted with up to 4 substituents, each of which is independently selected from halo; C 1 -C 3 straight or branched alkyl optionally substituted with N(R′) 2 , OR′, CO 2 R′, S(O 2 )N(R′) 2 , N═C—N(R′) 2 , R′, or CON(R′) 2 ; O—(C 1 -C 3 )-alkyl optionally substituted with N(R′) 2 , OR′, CO 2 R′, S(O 2 )N(R′) 2 , N═C—N(R′) 2 , R′, or CON(R′) 2 ; N(R′) 2 ; OCF 3 ; CF 3 ; NO 2 ; CON(R′) 2 ; R′; OR′; SR′; COR′; C(O)OR′; S(O 2 )N(R′) 2 ; SCF 3 ; N═C—N(R′) 2 ; or CN.
[0027] R′ is selected from hydrogen; (C 1 -C 3 )-alkyl; (C 2 -C 3 )-alkenyl or alkynyl; a 5-8 membered aryl ring system, a 5-8 membered heteroaryl ring system or a 5-6 membered heterocyclic ring system, any of which may be independently and optionally substituted with 1 to 3 substituents independently selected from halo, methoxy, cyano, nitro, amino, hydroxy, methyl or ethyl.
[0028] Provided that in compounds of Formula I, when A is C, B is N, Y is CHOH, O, S, CH 2 or NH, and R 3 is an N-containing heteroaryl, then R 1 is not aryl, carbocyclyl or pyridyl;
[0029] when A is N, B is C, Y is C═O and R 3 is a C 1 -C 8 alkyl, C 6 -C 1-2 aryl or C 7 -C 1-2 aralkyl, then R 1 is not 1-pyrroline or 1-indole; or
[0030] when A and B are both C, Y is CHOH or CH 2 , and R 3 is a substituted phenyl, then R 1 is not cyclopropyl or benzyl.
[0031] Further provided that in compounds of Formula II, when X is N, A and B are both C, Y is CH 2 or O, R 3 is a C 1-5 aliphatic, R 4 is NHR 5 , N(R 5 ) 2 , or a C 1-4 aliphatic substituted with a substituted or unsubstituted piperadine or piperazine; then R 1 is not CH3 or a ring system comprising a six-membered heteroaryl; or
[0032] in compounds of Formulae I and II, when X, if present, is N, A and B are both C, Y is CH 2 , R 1 is a C 1-8 aliphatic or is phenyl, R 4 , if present, is a C 1-6 aliphatic or is phenyl, and R 3 is a substituted C 5 alkyl or is methylene substituted with 4-hydroxy-tetrahydro-pyran-2-one, then Q is not simultaneously substituted with (a) a C 6-10 optionally substituted aryl, (b) C 1-10 aliphatic or carbocyclyl, and (c) a substituted C 6 alkyl or alkene, ethyl or ethylene substituted with 4-hydroxy-tetrahydro-pyran-2-one, CH 2 O subsituted with H, C 1-10 aliphatic, halo, phenyl, C 6-10 aryl or a carbonyl substituted with C 1-8 aliphatic or phenyl.
[0033] In another embodiment, the invention provides pharmaceutical compositions comprising a p38 inhibitor of this invention. These compositions may be utilized in methods for treating or preventing a variety of p38-mediated disorders, such as cancer, inflammatory diseases, autoimmune diseases, destructive bone disorders, proliferative disorders, infectious diseases, viral diseases and neurodegenerative diseases. These compositions are also useful in methods for preventing cell death and hyperplasia and therefore may be used to treat or prevent reperfusion/ischemia in stroke, heart attacks, and organ hypoxia. The compositions are also useful in methods for preventing thrombin-induced platelet aggregation. Each of these above-described methods is also part of the present invention.
[0034] In another embodiment, the invention provides methods of synthesizing compounds of formula I and pharmaceutical compositions comprising these compounds.
DETAILED DESCRIPTION OF THE INVENTION
[0035] As used herein, the following definitions shall apply unless otherwise indicated. Also, combinations of substituents or variables are permissible only if such combinations result in stable compounds.
[0036] The term “aliphatic” as used herein refers to a straight chained or branched hydrocarbon that is completely saturated or that contains one or more units of unsaturation. For example, aliphatic groups include substituted or unsubstituted linear or branched alkyl, alkenyl and alkynyl groups. Unless indicated otherwise, the term “aliphatic” encompasses both substituted and unsubstituted hydrocarbons. The term “alkyl” refers to both straight and branched saturated chains containing one to twelve carbon atoms. The terms “alkenyl” and “alkynyl” encompasses both straight and branched chains containing two to twelve carbon atoms and at least one unit of unsaturation.
[0037] The term “halogen” or “halo” means F, Cl, Br, or I.
[0038] The term “heteroatom” means N, O, or S and shall include any oxidized form of nitrogen and sulfur, such as N(O), S(O), S(O) 2 and the quaternized form of any basic nitrogen.
[0039] The term “carbocyclic” or “carbocyclyl” refers to a non-aromatic carbocyclic ring. A carbocyclic ring can be three to eight-membered. Further, a carbocyclic ring may be fused to another ring, such as a heterocyclic, aryl or heteroaryl ring, or another carbocyclic ring. A carbocyclic ring system may be monocyclic, bicyclic or tricyclic. The term “carbocyclic ring”, whether saturated or unsaturated, also refers to rings that are optionally substituted unless indicated.
[0040] The term “heterocyclic” or “heterocyclyl” refers to a non-aromatic heterocyclic ring in which one or more ring carbons in a non-aromatic carbocyclic ring is replaced by a heteroatom such as nitrogen, oxygen or sulfur in the ring. One having ordinary skill in the art will recognize that the maximum number of heteroatoms in a stable, chemically feasible heterocyclic ring is determined by the size of the ring, degree of unsaturation, and valence.
[0041] In general, a heterocyclic ring may have one to four heteroatoms so long as the heterocyclic ring is chemically feasible and stable. The ring can be five, six, seven or eight-membered and/or fused to another ring, such as a carbocyclic, aryl or heteroaryl ring or to another heterocyclic ring. A heterocyclic ring system may be monocyclic, bicyclic or tricyclic. The term “heterocyclic ring”, whether saturated or unsaturated, also refers to rings that are optionally substituted, unless otherwise indicated.
[0042] Examples of heterocyclic rings include, without limitation, 3-1H-benzimidazol-2-one, 3-(1-alkyl)-benzimidazol-2-one, 2-tetrahydrofuranyl, 3-tetrahydrofuranyl, 2-tetrahydrothiophenyl, 3-tetrahydrothiophenyl, 2-morpholino, 3-morpholino, 4-morpholino, 2-thiomorpholino, 3-thiomorpholino, 4-thiomorpholino, 1-pyrrolidinyl, 2-pyrrolidinyl, 3-pyrrolidinyl, 1-piperazinyl, 2-piperazinyl, 1-piperidinyl, 2-piperidinyl, 3-piperidinyl, 4-piperidinyl, 4-thiazolidinyl, diazolonyl, N-substituted diazolonyl, 1-phthalimidinyl, benzoxane, benzotriazol-1-yl, benzopyrrolidine, benzopiperidine, benzoxolane, benzothiolane, and benzothiane.
[0043] The term “aryl” refers to monocyclic, bicyclic or tricyclic carbocyclic aromatic ring systems having five to fourteen members. The term “aralkyl” refers to a aryl group comprising a (C 1 -C 3 ) alkyl group, wherein the alkyl group links the aralkyl group to the remainder of the molecule. Examples of aralkyl groups include benzyl and phenethyl. The term “aryl” includes aralkyl ring systems unless otherwise indicated. Aryl groups include, without limitation, phenyl, 1-naphthyl, 2-naphthyl, 1-anthracyl and 2-anthracyl. The term “aryl”, “aryl group” or “aryl ring” also refers to rings that are optionally substituted, unless otherwise indicated.
[0044] The term “heteroaryl” refers to monocyclic, bicyclic or tricyclic heterocyclic aromatic ring systems having five to fourteen members. One having ordinary skill in the art will recognize that the maximum number of heteroatoms in a stable, chemically feasible heteroaryl ring is determined by the size of the ring and valence. In general, a heteroaryl ring may have one to four heteroatoms so long as the heteroaryl ring is chemically feasible and stable. The term “heteroaralkyl” refers to a heteroaryl group comprising a (C 1 -C 3 ) alkyl group, wherein the alkyl group links the heteroaralkyl group to the remainder of the molecule. The term heteroaryl includes heteroaralkyl ring systems unless otherwise indicated. Heteroaryl groups include, without limitation, 2-furanyl, 3-furanyl, N-imidazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 2-oxadiazolyl, 5-oxadiazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-pyrrolyl, 3-pyrrolyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidyl, 4-pyrimidyl, 5-pyrimidyl, 3-pyridazinyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 5-tetrazolyl, 2-triazolyl, 5-triazolyl, 2-thienyl, or 3-thienyl. The term “heteroaryl ring” or “heteroaryl group” also refers to rings that are optionally substituted, unless otherwise indicated.
[0045] Examples of fused polycyclic heteroaryl and aryl ring systems in which a carbocyclic aromatic ring or heteroaryl ring is fused to one or more other rings include, without limitation, tetrahydronaphthyl, benzimidazolyl, benzothienyl, benzofuranyl, indolyl, quinolinyl, benzothiazolyl, benzooxazolyl, benzimidazolyl, isoquinolinyl, isoindolyl, acridinyl, benzoisoxazolyl, and the like. Also included within the scope of the term “aryl” and “heteroaryl”, as it is used herein, is a group in which one or more aryl rings and/or heteroaryl rings are fused to a non-aromatic cycloalkyl or heterocyclic ring, for example, indanyl or tetrahydrobenzopyranyl.
[0046] Suitable substituents on the unsaturated carbon atom of an aryl, heteroaryl, aralkyl, or heteroaralkyl group are selected from halogen; haloalkyl; —CF 3 ; —R 7 ; —OR 7 ; —SR 7 , 1,2-methylene-dioxy; 1,2-ethylenedioxy; protected OH (such as acyloxy); phenyl (Ph); Ph substituted with R 7 ; —O(Ph); —O(Ph) substituted with R 7 ; —CH 2 (Ph); —CH 2 (Ph) substituted with R 7 ; —CH 2 CH 2 (Ph); —CH 2 CH 2 (Ph) substituted with R 7 ; —NO 2 ; —CN; —N(R 7 ) 2 ; —NR 7 C(O)R 7 ; —NR 7 C(O)N(R 7 ) 2 ; —NR 7 CO 2 R 7 ; —NR 7 NR 7 C(O)R 7 ; —NR 7 NR 7 C(O)N(R 7 ) 2 ; —NR 7 NR 7 CO 2 R 7 ; —C(O)C(O)R 7 ; —C(O)CH 2 C(O)R 7 ; —CO 2 R 7 —C(O)R 7 ; —C(O)N(R 7 ) 2 ; —OC(O)N(R 7 ) 2 ; —S(O) 2 R 7 ; —SO 2 N(R 7 ) 2 ; —S(O)R 7 ; —NR 7 SO 2 N(R 7 ) 2 ; —NR 7 SO 2 R 7 ; —C(═S)N(R 7 ) 2 ; —C(═NH)—N(R 7 ) 2 ; —(CH 2 ) y NHC(O)R 7 ; —(CH 2 ) y R 7 ; —(CH 2 ) y NHC(O)NHR 7 ; —(CH 2 ) y NHC(O)OR 7 ; —(CH 2 ) y NHS(O)R 7 ; —(CH 2 ) y NHSO 2 R 7 ; —(CH 2 ) y NHC(O)CH(V z —R 7 )(R 7 ); wherein each R 7 is independently selected from H, optionally substituted C 1-6 aliphatic, an unsubstituted 5-10 membered heteroaryl or heterocyclic ring, phenyl (Ph), —O(Ph), or —CH 2 (Ph); wherein y is 0-6; z is 0-1; and V is a linker group. When R 7 is C 1-6 aliphatic, it may be substituted with one or more substituents selected from —NH 2 , —NH(C 1-4 aliphatic), —N(C 1-4 aliphatic) 2 , —S(O) (C 1-4 aliphatic), —SO 2 (C 1-4 aliphatic), halogen, —C 1-4 aliphatic, —OH, —O—(C 1-4 aliphatic), nitro, cyano, —CO 2 H, —CO 2 (C 1-4 aliphatic), —O(halo C 1-4 aliphatic), or -halo(C 1-4 aliphatic); wherein each C 1-4 aliphatic is unsubstituted.
[0047] An aliphatic group, a carbocyclic ring or a non-aromatic heterocyclic ring may contain one or more substituents. Suitable substituents on the saturated carbon of an aliphatic group or of a non-aromatic heterocyclic ring are selected from those listed above for the unsaturated carbon of an aryl or heteroaryl group and the following: ═O, ═S, ═NNHR 8 , ═NN(R 8 ) 2 , ═N—, OR 8 , ═NNHC(O)R 8 , ═NNHCO 2 (alkyl), ═NNHSO 2 (alkyl), or ═NR 8 , where each R 8 is independently selected from hydrogen, or an optionally substituted C 1-6 aliphatic group. When R 8 is C 1-6 aliphatic, it may be substituted with one or more substituents selected from amino, halogen, nitro, cyano, carboxy, t-butoxy, methoxy, ethoxy, hydroxy, or CF 3 .
[0048] Substituents on the nitrogen of a non-aromatic heterocyclic ring are selected from —R 9 , —N(R 9 ) 2 , —C(O)R 9 , —CO 2 R 9 , —C(O)C(O)R 9 , —C(O)CH 2 C(O)R 9 , —SO 2 R 9 , —SO 2 N(R 9 ) 2, —C(═S)N(R 9 ) 2 , —C(═NH)—N(R 9 ) 2, and —NR 9 SO 2 R 9 ; wherein each R 9 is independently selected from H, an optionally substituted C 1-6 aliphatic, optionally substituted phenyl (Ph), optionally substituted —O(Ph), optionally substituted —CH 2 (Ph), optionally substituted —CH 2 CH 2 (Ph), or an unsubstituted 5-6 membered heteroaryl or heterocyclic ring. When R 9 is a C 1-6 aliphatic group or a phenyl ring, it may be substituted with one or more substituents selected from —NH 2 , —NH(C 1-4 aliphatic), —N(C 1-4 aliphatic) 2, halogen, —(C 1-4 aliphatic), —OH, —O—(C 1-4 aliphatic), nitro, cyano, —CO 2 H, —CO 2 (C 1-4 aliphatic), —O(halo C 1-4 aliphatic), or -halo(C 1-4 aliphatic), wherein each C 1-4 aliphatic is unsubstituted.
[0049] The term “linker group” or “linker” means an organic moiety that connects two parts of a compound. Linkers are comprised of —O—, —S—, —NR*—, —C(R*) 2 —, —C(O)—, or an alkylidene chain. The alkylidene chain is a saturated or unsaturated, straight or branched, C 1-6 carbon chain which is optionally substituted, and wherein up to two non-adjacent saturated carbons of the chain are optionally replaced by —C(O)—, —C(O)C(O)—, —C(O)NR*—, —C(O)NR*NR*—, —CO 2 —, —OC(O)—, —NR*CO 2 —, —O—, —NR*C(O)NR*—, —OC(O)NR*—, —NR*NR*—, —NR*C(O)—, —S—, —SO—, —SO 2 —, —NR*—, —SO 2 NR*—, or —NR*SO 2 —; wherein R* is selected from hydrogen or aliphatic. Optional substituents on the alkylidene chain are as described above for an aliphatic group.
[0050] The term “patient” includes human and mammalian veterinary subjects.
[0051] One object of the instant invention is to provide compounds having the general formulae:
[0052] or a pharmaceutically acceptable derivative thereof, wherein:
[0053] A is N or CR.
[0054] B is N or CR.
[0055] X is N or CH.
[0056] Y is C(O), CHOH, CH 2 , S, S(O), S(O) 2 , NH, NR, O or Z.
[0057] Z is CHOH, —[(C 2 -C 3 )-alkyl]-, —S—[(C 1 -C 3 )-alkyl]-, —O—[(C 1 -C 3 )-alkyl]-, —NH—[(C 1 -C 3 )-alkyl]-, —[(C 2 -C 3 )-alkenyl]-, —[(C 2 -C 3 )-alkynyl]-, —O—[(C 2 -C 3 )-alkenyl]-, —O—[(C 2 -C 3 )-alkynyl]-, —S—[(C 2 -C 3 )-alkenyl]-, —S—[(C 2 -C 3 )-alkynyl]-, —NH—[(C 2 -C 3 )-alkenyl]-, —NH—[(C 2 -C 3 )- alkynyl]-, —[(C 1 -C 3 )-alkyl]-S—, —[(C 1 -C 3 )-alkyl]-O—, —[(C 1 -C 3 )-alkyl]-NH—, —[(C 2 -C 3 )-alkenyl]-O—, —[(C 2 -C 3 )-alkynyl]-O—, —[(C 2 -C 3 )-alkenyl]-S—, —[(C 2 -C 3 )-alkynyl]-S—, —[(C 2 -C 3 )-alkenyl]-NH— or —[(C 2 -C 3 )-alkynyl]-NH—.
[0058] The carbon atoms of Q may be optionally substituted with R.
[0059] R 1 is selected from aryl, heteroaryl, carbocyclyl, heterocyclyl or C 1-10 aliphatic, any of which may be optionally substituted.
[0060] R 3 is selected from aryl, heteroaryl, carbocyclyl, heterocyclyl, or C 1-10 aliphatic, any of which may be optionally substituted.
[0061] R 4 is selected from NHR 5 , N(R 5 ) 2 , OR 5 , C(O)OR 5 , —C(O)R 5 or R 6 .
[0062] Each R 5 is independently selected from aryl, heteroaryl, carbocyclyl, heterocyclyl or C 1-5 aliphatic;
[0063] R 6 is selected from aryl, heteroaryl, carbocyclyl, heterocyclyl or C 1-5 aliphatic, any of which may be optionally substituted.
[0064] Each R is independently selected from H, halo or a straight or branched chain C 1 -C 4 alkyl.
[0065] Each of R 1 , R 5 and R 6 are independently and optionally substituted with up to 4 substituents, each of which is independently selected from halo; C 1 -C 3 alkyl optionally substituted with NR′ 2 , OR′, CO 2 R′ or CONR′ 2 ; O—(C 1 -C 3 )-alkyl optionally substituted with NR′ 2 , OR′, CO 2 R′or CONR′ 2 ; R′; NR′ 2 ; OCF 3 ; CF 3 ; NO 2 ; CO 2 R′; CONR′; SR′; COR′; S(O 2 )N(R′) 2 ; SCF 3 ; CN; N(R′)C(O)R′; N(R′)C(O)OR′; N(R′)C(O)C(O)R′; N(R′)S(O 2 )R′; OR′; OC(O)R′; OP(O) 3 H 2 ; or N═C—N(R′) 2 .
[0066] R 3 is optionally substituted with up to 4 substituents, each of which is independently selected from halo; C 1 -C 3 straight or branched alkyl optionally substituted with N(R′) 2 , OR′, CO 2 R′, S(O 2 )N(R′) 2 , N═C—N(R′) 2 , R′, or CON(R′) 2 ; O—(C 1 -C 3 )-alkyl optionally substituted with N(R′) 2 , OR′, CO 2 R′, S(O 2 )N(R′) 2 , N═C—N(R′) 2 , R′, or CON(R′) 2 ; N(R′) 2 ; OCF 3 ; CF 3 ; NO 2 ; CON(R′) 2 ; R′; OR′; SR′; COR′; C(O)OR′; S(O 2 )N(R′) 2 ; SCF 3 ; N═C—N(R′) 2 ; or CN.
[0067] R′ is selected from hydrogen; (C 1 -C 3 )-alkyl; (C 2 -C 3 )-alkenyl or alkynyl; a 5-8 membered aryl ring system, a 5-8 membered heteroaryl ring system or a 5-6 membered heterocyclic ring system, any of which may be independently and optionally substituted with 1 to 3 substituents independently selected from halo, methoxy, cyano, nitro, amino, hydroxy, methyl or ethyl.
[0068] Provided that in compounds of Formula I, when A is C, B is N, Y is CHOH, O, S, CH 2 or NH, and R 3 is an N-containing heteroaryl, then R 1 is not aryl, carbocyclyl or pyridyl;
[0069] when A is N, B is C, Y is C═O and R 3 is a C 1 -C 8 alkyl, C 6 -C 1-2 aryl or C 7 -C 1-2 aralkyl, then R 1 is not 1-pyrroline or 1-indole; or
[0070] when A and B are both C, Y is CHOH or CH 2 , and R 3 is a substituted phenyl, then R 1 is not cyclopropyl or benzyl.
[0071] Further provided that in compounds of Formula II, when X is N, A and B are both C, Y is CH 2 or 0, R 3 is a C 1-5 aliphatic, R 4 is NHR 5 , N(R 5 ) 2 , or a C 1-4 aliphatic substituted with a substituted or unsubstituted piperadine or piperazine; then R 1 is not CH 3 or a ring system comprising a six-membered heteroaryl; or in compounds of Formulae I and II, when X, if present, is N, A and B are both C, Y is CH 2 , R 1 is a C 1-8 aliphatic or is phenyl, R 4 , if present, is a C 1-6 aliphatic or is phenyl, and R 3 is a substituted C 5 alkyl or is methylene substituted with 4-hydroxy-tetrahydro-pyran-2-one, then Q is not simultaneously substituted with (a) a C 6-10 optionally substituted aryl, (b) C 1-10 aliphatic or carbocyclyl, and (c) a substituted C 6 alkyl or alkene, ethyl or ethylene substituted with 4-hydroxy-tetrahydro-pyran-2-one, CH 2 O subsituted with H, C 1-10 aliphatic, halo, phenyl, C 6-10 aryl or a carbonyl substituted with C 1-8 aliphatic or phenyl.
[0072] It will be apparent to one skilled in the art that certain compounds of this invention may exist in tautomeric forms, all such tautomeric forms of the compounds being within the scope of the invention.
[0073] Unless otherwise stated, structures depicted herein are also meant to include all stereochemical forms of the structure; i.e., the R and S configurations for each asymmetric center. Therefore, single stereochemical isomers as well as enantiomeric and diastereomeric mixtures of the present compounds are within the scope of the invention. Unless otherwise stated, structures depicted herein are also meant to include compounds which differ only in the presence of one or more isotopically enriched atoms. For example, compounds having the present structures except for the replacement of a hydrogen by a deuterium or tritium, or the replacement of a carbon by a 13 C- or 14 C-enriched carbon are within the scope of this invention.
[0074] In a preferred embodiment of the invention, either A or B are C. In a more preferred embodiment, both A and B are C. In another preferred embodiment, R 1 is aryl or heteroaryl. In yet another preferred embodiment of formulae I and II, Y is C(O). In another preferred embodiment of formulae II and III, X is N.
[0075] A more preferred embodiment of the invention is shown in formula Ia:
[0076] (Ia), wherein R 1 and R 3 are defined above. In an even more preferred embodiment, R 1 is selected from phenyl or pyridyl containing 1 to 3 substituents, and R 3 is selected from phenyl, thienyl or pyridyl containing 0 to 3 substituents.
[0077] Another more preferred embodiment of the invention is shown in formula IIa:
[0078] (IIa), wherein R 1 and R 3 are defined above. In an even more preferred embodiment, R 1 is selected from phenyl or pyridyl containing 1 to 3 substituents, and R 3 is selected from phenyl, thienyl or pyridyl containing 0 to 3 substituents.
[0079] According to another preferred embodiment of the invention, R 1 is selected from phenyl or pyridyl containing 1 to 3 substituents. More preferably, said substituents are independently selected from chloro, fluoro, bromo, —CH 3 , —OCH 3 , —OH, —CF 3 , —OH, —CF 3 , —O(CH 2 ) 2 CH 3 , NH 2 , 3,4-methylenedioxy, —N(CH 3 ) 2 , —NH—S(O) 2 -phenyl, —NH—C(O)O—CH 2 -4-pyridine, —NH—C(O)CH 2 -morpholine, —NH—C(O)CH 2 —N(CH 3 ) 2 , —NH—C(O)CH 2 -piperazine, —NH—C(O)CH 2 -pyrrolidine, —NH—C(O)C(O)-morpholine, —NH—C(O)C(O)-piperazine, —NH—C(O)C(O)-pyrrolidine, —O—C(O)CH 2 —N(CH 3 ) 2 , or —O—(CH 2 ) 2 —N(CH 3 ) 2 . Even more preferably, at least one of said substituents is in the ortho position.
[0080] Even more preferred for R 1 are phenyl or pyridyl containing at least 2 of the above-indicated substituents both being in the ortho position.
[0081] According to a preferred embodiment, R 3 is aliphatic, phenyl, pyridyl, thienyl or naphthyl and optionally contains up to 3 substituents, each of which is independently selected from chloro, fluoro, bromo, methyl, ethyl, isopropyl, —OCH 3 , —OH, —NH 2 , —CF 3 , —OCF 3 , —SCH 3 , —OCH 3 , —C(O)OH, —C(O)OCH 3 , —CH 2 NH 2 , —N(CH 3 ) 2 , pyrrolyl, —CH 2 -pyrrolidine and —CH 2 OH.
[0082] Some specific examples of preferred R 3 are: n-butyl, isobutyl, unsubstituted phenyl,
[0083] According to another preferred embodiment of the invention, R 4 , if present, is selected from phenyl, —C(CH 3 ) 3 , —CH 2 OCH 3 , —CH 3 , 4-bromophenyl, cyclohexane, —CH 2 CH 2 C(O)OCH 3 , 3-trifluoromethylphenyl, 3-trifluoromethyl-4-fluorophenyl, —C(O)OCH 2 CH 3 , —CH 2 CH(CH 3 ) 2 , —CH 2 CH 2 -phenyl, —CH 2 -4-fluorophenyl, —OCH 2 -phenyl, —O-4fluorophenyl,
[0084] Some preferred embodiments are provided in Tables 1-6 below:
TABLE 1 Cpd. No. Structure 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
[0085] [0085] TABLE 2 Cpd. No. Structure 201
[0086] [0086] TABLE 3 Cpd. No. Structure 301
[0087] [0087] TABLE 4 Cpd. No. Structure 401 402
[0088] [0088] TABLE 5 Cpd. No. Structure 501 502 503
[0089] [0089] TABLE 6 Cpd. No. Structure 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635
[0090] According to another embodiment, the present invention provides methods of producing the above-identified compounds. Representative synthesis schemes are depicted in Examples 1-9 below.
[0091] According to another embodiment of the invention, the activity of the p38 inhibitors of this invention may be assayed in vitro, in vivo or in a cell line. In vitro assays include assays that determine inhibition of either the kinase activity or ATPase activity of activated p38. Alternate in vitro assays quantitate the ability of the inhibitor to bind to p38 and may be measured either by radiolabelling the inhibitor prior to binding, isolating the inhibitor/p38 complex and determining the amount of radiolabel bound, or by running a competition experiment where new inhibitors are incubated with p38 bound to known radioligands.
[0092] Cell culture assays of the inhibitory effect of the compounds of this invention may determine the amounts of TNF, IL-1, IL-6 or IL-8 produced in whole blood or cell fractions thereof in cells treated with inhibitor as compared to cells treated with negative controls. Level of these cytokines may be determined through the use of commercially available ELISAs.
[0093] An in vivo assay useful for determining the inhibitory activity of the p38 inhibitors of this invention are the suppression of hind paw edema in rats with Mycobacterium butyricum -induced adjuvant arthritis. This is described in J. C. Boehm et al., J. Med. Chem., 39, pp. 3929-37 (1996), the disclosure of which is herein incorporated by reference. The p38 inhibitors of this invention may also be assayed in animal models of arthritis, bone resorption, endotoxin shock and immune function, as described in A. M. Badger et al., J. Pharmacol. Experimental Therapeutics, 279, pp. 1453-61 (1996), the disclosure of which is herein incorporated by reference.
[0094] The p38 inhibitors or pharmaceutical salts thereof may be formulated into pharmaceutical compositions for administration to animals or humans. These pharmaceutical compositions, which comprise an amount of p38 inhibitor effective to treat or prevent a p38-mediated condition and a pharmaceutically acceptable carrier, are another embodiment of the present invention.
[0095] The term “p38-mediated condition”, as used herein means any disease or other deleterious condition in which p38 is known to play a role. This includes conditions known to be caused by IL-1, TNF, IL-6 or IL-8 overproduction. Such conditions include, without limitation, inflammatory diseases, autoimmune diseases, destructive bone disorders, proliferative disorders, infectious diseases, neurodegenerative diseases, allergies, reperfusion/ischemia in stroke, heart attacks, angiogenic disorders, organ hypoxia, vascular hyperplasia, cardiac hypertrophy, thrombin-induced platelet aggregation, and conditions associated with prostaglandin endoperoxidase synthase-2.
[0096] Inflammatory diseases which may be treated or prevented by the compounds of this invention include, but are not limited to, acute pancreatitis, chronic pancreatitis, asthma, allergies, and adult respiratory distress syndrome.
[0097] Autoimmune diseases which may be treated or prevented by the compounds of this invention include, but are not limited to, glomerulonephritis, rheumatoid arthritis, systemic lupus erythematosus, scleroderma, chronic thyroiditis, Graves' disease, autoimmune gastritis, diabetes, autoimmune hemolytic anemia, autoimmune neutropenia, thrombocytopenia, atopic dermatitis, chronic active hepatitis, myasthenia gravis, multiple sclerosis, inflammatory bowel disease, ulcerative colitis, Crohn's disease, psoriasis, or graft vs. host disease.
[0098] Destructive bone disorders which may be treated or prevented by the compounds of this invention include, but are not limited to, osteoporosis, osteoarthritis and multiple myeloma-related bone disorder.
[0099] Proliferative diseases which may be treated or prevented by the compounds of this invention include, but are not limited to, acute myelogenous leukemia, chronic myelogenous leukemia, metastatic melanoma, Kaposi's sarcoma, and multiple myeloma.
[0100] Angiogenic disorders which may be treated or prevented by the compounds of this invention include solid tumors, ocular neovasculization, infantile haemangiomas.
[0101] Infectious diseases which may be treated or prevented by the compounds of this invention include, but are not limited to, sepsis, septic shock, and Shigellosis.
[0102] Viral diseases which may be treated or prevented by the compounds of this invention include, but are not limited to, acute hepatitis infection (including hepatitis A, hepatitis B and hepatitis C), HIV infection and CMV retinitis.
[0103] Neurodegenerative diseases which may be treated or prevented by the compounds of this invention include, but are not limited to, Alzheimer's disease, Parkinson's disease, cerebral ischemias or neurodegenerative disease caused by traumatic injury.
[0104] “p38-mediated conditions” also include ischemia/reperfusion in stroke, heart attacks, myocardial ischemia, organ hypoxia, vascular hyperplasia, cardiac hypertrophy, and thrombin-induced platelet aggregation.
[0105] In addition, p38 inhibitors of the instant invention are also capable of inhibiting the expression of inducible pro-inflammatory proteins such as prostaglandin endoperoxide synthase-2 (PGHS-2), also referred to as cyclooxygenase-2 (COX-2). Therefore, other “p38-mediated conditions” which may be treated by the compounds of this invention include edema, analgesia, fever and pain, such as neuromuscular pain, headache, cancer pain, dental pain and arthritis pain.
[0106] The diseases that may be treated or prevented by the p38 inhibitors of this invention may also be conveniently grouped by the cytokine (IL-1, TNF, IL-6, IL-8) that is believed to be responsible for the disease.
[0107] Thus, an IL-1-mediated disease or condition includes rheumatoid arthritis, osteoarthritis, stroke, endotoxemia and/or toxic shock syndrome, inflammatory reaction induced by endotoxin, inflammatory bowel disease, tuberculosis, atherosclerosis, muscle degeneration, cachexia, psoriatic arthritis, Reiter's syndrome, gout, traumatic arthritis, rubella arthritis, acute synovitis, diabetes, pancreatic β-cell disease and Alzheimer's disease.
[0108] TNF-mediated disease or condition includes, rheumatoid arthritis, rheumatoid spondylitis, osteoarthritis, gouty arthritis and other arthritic conditions, sepsis, septic shock, endotoxic shock, gram negative sepsis, toxic shock syndrome, adult respiratory distress syndrome, cerebral malaria, chronic pulmonary inflammatory disease, silicosis, pulmonary sarcoidosis, bone resorption diseases, reperfusion injury, graft vs. host reaction, allograft rejections, fever and myalgias due to infection, cachexia secondary to infection, AIDS, ARC or malignancy, keloid formation, scar tissue formation, Crohn's disease, ulcerative colitis or pyresis. TNF-mediated diseases also include viral infections, such as HIV, CMV, influenza and herpes; and veterinary viral infections, such as lentivirus infections, including, but not limited to equine infectious anemia virus, caprine arthritis virus, visna virus or maedi virus; or retrovirus infections, including feline immunodeficiency virus, bovine immunodeficiency virus, or canine immunodeficiency virus.
[0109] IL-8 mediated disease or condition includes diseases characterized by massive neutrophil infiltration, such as psoriasis, inflammatory bowel disease, asthma, cardiac and renal reperfusion injury, adult respiratory distress syndrome, thrombosis and glomerulonephritis.
[0110] In addition, the compounds of this invention may be used topically to treat or prevent conditions caused or exacerbated by IL-1 or TNF. Such conditions include inflamed joints, eczema, psoriasis, inflammatory skin conditions such as sunburn, inflammatory eye conditions such as conjunctivitis, pyresis, pain and other conditions associated with inflammation.
[0111] A “pharmaceutically acceptable derivative or prodrug” means any pharmaceutically acceptable salt, ester, salt of an ester or other derivative of a compound of this invention which, upon administration to a recipient, is capable of providing, either directly or indirectly, a compound of this invention or an inhibitorily active metabolite or residue thereof. Particularly favored derivatives or prodrugs are those that increase the bioavailability of the compounds of this invention when such compounds are administered to a mammal (e.g., by allowing an orally administered compound to be more readily absorbed into the blood) or which enhance delivery of the parent compound to a biological compartment (e.g., the brain or lymphatic system) relative to the parent species.
[0112] Pharmaceutically acceptable prodrugs of the compounds of this invention include, without limitation, esters, amino acid esters, phosphate esters, metal salts and sulfonate esters.
[0113] Pharmaceutically acceptable salts of the compounds of this invention include those derived from pharmaceutically acceptable inorganic and organic acids and bases. Examples of suitable acid salts include acetate, adipate, alginate, aspartate, benzoate, benzenesulfonate, bisulfate, butyrate, citrate, camphorate, camphorsulfonate, cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate, formate, fumarate, glucoheptanoate, glycerophosphate, glycolate, hemisulfate, heptanoate, hexanoate, hydrochloride, hydrobromide, hydroiodide, 2-hydroxyethanesulfonate, lactate, maleate, malonate, methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oxalate, palmoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate, pivalate, propionate, salicylate, succinate, sulfate, tartrate, thiocyanate, tosylate and undecanoate. Other acids, such as oxalic, while not in themselves pharmaceutically acceptable, may be employed in the preparation of salts useful as intermediates in obtaining the compounds of the invention and their pharmaceutically acceptable acid addition salts. Salts derived from appropriate bases include alkali metal (e.g., sodium and potassium), alkaline earth metal (e.g., magnesium), ammonium and N—(C 1-4 alkyl) 4 +salts. This invention also envisions the quaternization of any basic nitrogen-containing groups of the compounds disclosed herein. Water or oil-soluble or dispersible products may be obtained by such quaternization.
[0114] Pharmaceutically acceptable salts include salts of organic carboxylic acids such as ascorbic, acetic, citric, lactic, tartaric, malic, maleic, isothionic, lactobionic, p-aminobenzoic and succinic acids; organic sulphonic acids such as methanesulphonic, ethanesulphonic, benzenesulphonic and p-toluenesulphonic acids and inorganic acids such as hydrochloric, sulphuric, phosphoric, sulphamic and pyrophosphoric acids.
[0115] Preferred salts include salts formed from hydrochloric, sulfuric, acetic, succinic, citric and ascorbic acids.
[0116] Pharmaceutically acceptable carriers that may be used in these pharmaceutical compositions include, but are not limited to, ion exchangers, alumina, aluminum stearate, lecithin, serum proteins, such as human serum albumin, buffer substances such as phosphates, glycine, sorbic acid, potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, water, salts or electrolytes, such as protamine sulfate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose-based substances, polyethylene glycol, sodium carboxymethylcellulose, polyacrylates, waxes, polyethylene-polyoxypropylene-block polymers, polyethylene glycol and wool fat.
[0117] The compositions of the present invention may be administered orally, parenterally, by inhalation spray, topically, rectally, nasally, buccally, vaginally or via an implanted reservoir. The term “parenteral” as used herein includes subcutaneous, intravenous, intramuscular, intra-articular, intra-synovial, intrasternal, intrathecal, intrahepatic, intralesional and intracranial injection or infusion techniques. Preferably, the compositions are administered orally, intraperitoneally or intravenously.
[0118] Sterile injectable forms of the compositions of this invention may be aqueous or oleaginous suspension. These suspensions may be formulated according to techniques known in the art using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent, for example as a solution in 1,3-butanediol. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose, any bland fixed oil may be employed including synthetic mono- or di-glycerides. Fatty acids, such as oleic acid and its glyceride derivatives are useful in the preparation of injectables, as are natural pharmaceutically-acceptable oils, such as olive oil or castor oil, especially in their polyoxyethylated versions. These oil solutions or suspensions may also contain a long-chain alcohol diluent or dispersant, such as carboxymethyl cellulose or similar dispersing agents which are commonly used in the formulation of pharmaceutically acceptable dosage forms including emulsions and suspensions. Other commonly used surfactants, such as Tweens, Spans and other emulsifying agents or bioavailability enhancers which are commonly used in the manufacture of pharmaceutically acceptable solid, liquid, or other dosage forms may also be used for the purposes of formulation.
[0119] The pharmaceutical compositions of this invention may be orally administered in any orally acceptable dosage form including, but not limited to, capsules, tablets, aqueous suspensions or solutions. In the case of tablets for oral use, carriers commonly used include lactose and corn starch. Lubricating agents, such as magnesium stearate, are also typically added. For oral administration in a capsule form, useful diluents include lactose and dried cornstarch. When aqueous suspensions are required for oral use, the active ingredient is combined with emulsifying and suspending agents. If desired, certain sweetening, flavoring or coloring agents may also be added.
[0120] Alternatively, the pharmaceutical compositions of this invention may be administered in the form of suppositories for rectal administration. These can be prepared by mixing the agent with a suitable non-irritating excipient which is solid at room temperature but liquid at rectal temperature and therefore will melt in the rectum to release the drug. Such materials include cocoa butter, beeswax and polyethylene glycols.
[0121] The pharmaceutical compositions of this invention may also be administered topically, especially when the target of treatment includes areas or organs readily accessible by topical application, including diseases of the eye, the skin, or the lower intestinal tract. Suitable topical formulations are readily prepared for each of these areas or organs.
[0122] Topical application for the lower intestinal tract can be effected in a rectal suppository formulation (see above) or in a suitable enema formulation. Topically-transdermal patches may also be used.
[0123] For topical applications, the pharmaceutical compositions may be formulated in a suitable ointment containing the active component suspended or dissolved in one or more carriers. Carriers for topical administration of the compounds of this invention include, but are not limited to, mineral oil, liquid petrolatum, white petrolatum, propylene glycol, polyoxyethylene, polyoxypropylene compound, emulsifying wax and water. Alternatively, the pharmaceutical compositions can be formulated in a suitable lotion or cream containing the active components suspended or dissolved in one or more pharmaceutically acceptable carriers. Suitable carriers include, but are not limited to, mineral oil, sorbitan monostearate, polysorbate 60, cetyl esters wax, cetearyl alcohol, 2-octyldodecanol, benzyl alcohol and water.
[0124] For ophthalmic use, the pharmaceutical compositions may be formulated as micronized suspensions in isotonic, pH adjusted sterile saline, or, preferably, as solutions in isotonic, pH adjusted sterile saline, either with or without a preservative such as benzylalkonium chloride. Alternatively, for ophthalmic uses, the pharmaceutical compositions may be formulated in an ointment such as petrolatum.
[0125] The pharmaceutical compositions of this invention may also be administered by nasal aerosol or inhalation. Such compositions are prepared according to techniques well-known in the art of pharmaceutical formulation and may be prepared as solutions in saline, employing benzyl alcohol or other suitable preservatives, absorption promoters to enhance bioavailability, fluorocarbons, and/or other conventional solubilizing or dispersing agents.
[0126] The amount of p38 inhibitor that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. Preferably, the compositions should be formulated so that a dosage of between 0.01-100 mg/kg body weight/day of the inhibitor can be administered to a patient receiving these compositions.
[0127] It should also be understood that a specific dosage and treatment regimen for any particular patient will depend upon a variety of factors, including the activity of the specific compound employed, the age, body weight, general health, sex, diet, time of administration, rate of excretion, drug combination, and the judgment of the treating physician and the severity of the particular disease being treated. The amount of inhibitor will also depend upon the particular compound in the composition.
[0128] According to another embodiment, the invention provides methods for treating or preventing a p38-mediated condition comprising the step of administering to a patient one of the above-described pharmaceutical compositions. The term “patient”, as used herein, means an animal, preferably a human.
[0129] Preferably, that method is used to treat or prevent a condition selected from inflammatory diseases, autoimmune diseases, destructive bone disorders, proliferative disorders, infectious diseases, degenerative diseases, allergies, reperfusion/ischemia in stroke, heart attacks, angiogenic disorders, organ hypoxia, vascular hyperplasia, cardiac hypertrophy, and thrombin-induced platelet aggregation.
[0130] According to another embodiment, the inhibitors of this invention are used to treat or prevent an IL-1, IL-6, IL-8 or TNF-mediated disease or condition. Such conditions are described above.
[0131] Depending upon the particular p38-mediated condition to be treated or prevented, additional drugs, which are normally administered to treat or prevent that condition, may be administered together with the inhibitors of this invention. For example, chemotherapeutic agents or other anti-proliferative agents may be combined with the p38 inhibitors of this invention to treat proliferative diseases.
[0132] Those additional agents may be administered separately, as part of a multiple dosage regimen, from the p38 inhibitor-containing composition. Alternatively, those agents may be part of a single dosage form, mixed together with the p38 inhibitor in a single composition.
[0133] In order that the invention described herein may be more fully understood, the following examples are set forth. It should be understood that these examples are for illustrative purposes only and are not to be construed as limiting this invention in any manner.
EXAMPLE 1
Synthesis of [6-(2,6-Difluorophenylamino)-pyridin-3-yl] Arylmethanones
[0134] [0134]
[0135] To stirred suspension of sodium hydride (1.9 equivalents [eq.]) in tetrohydrofuran (THF) (10 ml/g) at room temperature was added dropwise a solution of 2,6-difluoroaniline (1.5 eq.) in THF (8 ml/g). The resultant mixture was stirred at room temperature for 30 minutes. A solution of 2,5-dibromopyridine (1.0 eq.) in THF (8 ml/g) was added and the resultant mixture was stirred at room temperature for 10 minutes prior to being heated to 65° C. overnight. The reaction was cooled, quenched with water and extracted with 3 portions of diethyl ether. The combined organic extracts were dried over MgSO 4 and concentrated in vacuo to give the desired product. No further purification was required.
[0136] To a stirred solution of sodium hydride (2 eq.) in rigorously degassed THF (approximately 20 mL/g) at 0° C. was added dropwise a solution of (5-Bromopyridin-2-yl)-(2,6-difluorophenyl)-amine in THF (approximately 10 mL/g). The solution was allowed to warm slowly to room temperature over 1 hour, after which time the solution was cooled to −78° C. n-Butyllithium (approximately 1.6 M in hexanes, 1.1 eq.) was added dropwise over 15 minutes and the resultant solution was stirred at −78° C. for 1 hour. The ‘dianion’ solution was then added via a cooled cannula to a solution of the appropriate methoxy arylcarbonyl (1.1 eq.) in THF (approximately 10 mL/g) at −78° C. After stirring at −78° C. for at least 5 hours, the reaction was quenched with a methanolic solution of ammonium chloride at −78° C. and allowed to warm slowly to room temperature. The solution was partitioned between ethyl acetate and water (equal volumes, using approximately 25 mL/g of 2-(2,6-difluoro)aniline-5-bromo-pyridine used). The organic layer was removed and the aqueous layer re-extracted with ethyl acetate (approximately 25 mL/g). The combined organic layer was washed with saturated aqueous brine solution (approximately 25 mL/g), dried over MgSO 4 and concentrated in vacuo to give the crude reaction product, which was typically purified by column chromatography, using various ratios of ethyl acetate:hexane as eluant.
[0137] One having ordinary skill in the art may synthesize other arylmethanones following the teachings of the specification. For instance, one may use other than (2,6-difluorophenyl)-amine to prepare compounds having a different R 1 . Further, one may use heteroarylmethanones to synthesize compounds of this invention having a heteroaryl for R 1 .
EXAMPLE 2
Synthesis of 2-(2,6-Difluoro) Aniline-5-Alkyl-Pyridines
[0138] [0138]
[0139] The compounds were produced as for the arylketones shown above in Scheme 1, except that an alkyl iodide (1.1 eq.) was employed as the electrophile, and was added directly to the ‘dianion’ solution. The reactions did not require low temperature quenching and were allowed to warm to room temperature overnight, before work-up. One having ordinary skill in the art may synthesize other alkylketones following the teachings of the instant specification.
EXAMPLE 3
Synthesis of 2-(2,6-Difluoro) Aniline-5-Arylsulfenyl/Arylsulfinyl/Arylsulfonyl-Pyridines
[0140] [0140]
[0141] The compounds were produced as for the arylketones shown above in Scheme 1, except that an appropriate sulfur electrophile (a diaryldisulfide for sulfenyl-pyridines or an arylsulfonyl halide for sulfonyl-pyridines) (1.1 eq.) was employed as the electrophile, and was added directly to the ‘dianion’ solution. The reactions were quenched with a methanolic solution of ammonium chloride at −78° C., before work-up. Sulfinyl-pyridines were synthesized by oxidizing the corresponding sulfenyl-pyridines at 0° C. using meta-chloroperbenzoic acid (m-CPBA; 1.1 eq. of approximately 50% w/w). One having ordinary skill in the art may synthesize other arylsulfenyl, arylsulfinyl and arylsulfonyl pyridines or heteroarylsulfenyl, heteroarylsulfinyl or heteroarylsulfonyl pyridines following the teachings of the specification.
EXAMPLE 4
Part A: Synthesis of (2,6-Difluoro-phenyl)-(5-iodo-pyridin-2-yl)-amine
[0142] [0142]
[0143] To a stirred solution of sodium hydride (2 eq.) in rigorously degassed THF (approximately 50 mL/g) at 0° C., was added dropwise a solution of (2,6-difluorophenyl)-(5-bromopyridin-2-yl)-amine (1 eq.) in THF (approximately 15 mL/g). The solution was allowed to warm slowly to room temperature over 1 hour, after which time the solution was cooled to −78° C. n-Butyllithium (approximately 1.6 M in hexanes, 1.1 eq.) was added dropwise over 15 minutes and the resultant solution was stirred at −78° C. for 1 hour. Zinc chloride/TMEDA complex (prepared as described by Isobe et al., Chem. Lett., 1977, 679) was added as a solid in a single portion and the solution was allowed to warm to 0° C. over 30 minutes, and was stirred at 0° C. for a further 1 hour. A solution of iodine (1.1 eq.) in THF (approximately 10 mL/g) was added and the solution was allowed to warm to room temperature. After stirring at room temperature for at least 1 hour, the reaction was quenched with a saturated aqueous solution of ammonium chloride. The solution was extracted with diethyl ether (3 times approximately 50 mL/g of 5-Bromopyridin-2-yl)-(2,6-difluorophenyl)-amine used). The combined organic layer was washed successively with 10% aqueous sodium sulfite solution (approximately 50 mL/g), saturated aqueous sodium thiosulfate solution (approximately 50 mL/g) and water (approximately 50 mL/g), dried over MgSO 4 and concentrated in vacuo to give the crude reaction product as an orange oil. Purification by column chromatography, using 10% ethyl acetate:hexane as eluant, provided (2,6-Difluoro-phenyl)-(5-iodo-pyridin-2-yl)-amine (Rf 0.22) in approximately 50% yield.
[0144] Part B: Synthesis of (2,6-Difluoro-phenyl)-(5-vinyl-pyridin-2-yl)-amine
[0145] To a mixture of (2,6-Difluoro-phenyl)-(5-iodo-pyridin-2-yl)-amine and Pd(PPh3) 4 (approximately 10 mol %) in toluene (approximately. 80 mL/g) at room temperature was added tributylvinyltin (1.1 eq.). The reaction was placed under a N 2 atmosphere and heated to 80° C. overnight. The solution was cooled, diluted with ethyl acetate (approximately 80 mL/g) and filtered through a pad of celite. The celite was washed with a further portion of ethyl acetate. The organic layer was dried over MgSO 4 and concentrated in vacuo to give the crude reaction product as a yellow oil. Purification by column chromatography, using 10% ethyl acetate:hexane as eluant provided (2,6-Difluoro-phenyl)-(5-vinyl-pyridin-2-yl)-amine (Rf 0.14) in 66% yield.
[0146] Part C: Synthesis of (2,6-Difluorophenyl)-(5-alkynyl-pyridin-2-yl)-amine
[0147] To a mixture of copper (I) iodide (approximately 5 mol %) and PdCl 2 (PPh 3 ) 2 (approximately 5 mol %) was added a solution of 2-(2,6-difluoro)aniline-5-iodo-pyridine in triethylamine (approximately 25 mL/g) at room temperature. The reaction was placed under a N 2 atmosphere and the appropriate alkyne (1.1 eq.) added dropwise. The reaction was stirred at room temperature or 50° C. (dependent on the alkyne) overnight. The solution was cooled, poured onto 10% aqueous hydrochloric acid (approximately 250 mL/g of 2-(2,6-difluoro)aniline-5-iodo-pyridine used). The aqueous layer was extracted with diethyl ether (2 times approximately 500 mL/g), and the organic layer washed with saturated aqueous brine solution (approximately 500 mL/g). The organic layer was dried over MgSO 4 and concentrated in vacuo to give the crude reaction product, which was purified by column chromatography, using various ratios of ethyl acetate:hexane as eluant. One having ordinary skill in the art may synthesize other alkynyl pyridinyl amines following the teachings of the instant specification.
EXAMPLE 6
Part A: Synthesis of (6-Chloropyridazin-3-yl)-(2,6-difluorophenyl)-acetonitrile
[0148] [0148]
[0149] To a stirred solution of the appropriate phenylacetonitrile in rigorously degassed THF (approximately 10 mL/g) under N 2 at 0° C. was added dropwise a 1M solution of potassium t-butoxide in THF (1.1 eq.). After stirring at 0° C. for 30 minutes a solution of 3,6-dichloropyridazine (1 eq.) in rigorously degassed THF (approximately 10 mL/g) was added. The solution was stirred at room temperature for 17 hours and was then quenched with saturated aqueous ammonium chloride (approximately 20 mL/g). The mixture was filtered and the precipitate was washed with ethyl acetate (approximately 20 mL/g). Water (approximately 20 mL/g) was added to the filtrate and the organic layer was collected and the aqueous layer re-extracted with ethyl acetate (approximately 20 mL/g). The combined organic layer was washed with saturated aqueous brine solution (approximately 20 mL/g), dried over MgSO 4 and concentrated in vacuo to give the crude reaction product, which was purified by column chromatography using various ratios of ethyl acetate:hexane as eluant.
[0150] Part B: Synthesis of 2-(6-Chloropyridazin-3-yl)-2-(2,6-difluorophenyl)-acetamide
[0151] The 2-aryl-2-(6-chloro-pyridazin-2,3-yl) acetonitrile (1 eq.) was dissolved in concentrated sulfuric acid (approximately 10 mL/g) at room temperature, and the solution was heated to 90° C. and maintained at this temperature for 15 minutes. The reaction mixture was then poured slowly onto crushed ice (approximately 25 g/g of 2-aryl-2-(6-chloro-pyridazin-2,3-yl) acetonitrile used). Ethyl acetate (approximately 25 mL/g) was added, the organic layer was collected, and the aqueous layer re-extracted with ethyl acetate (approximately 25 mL/g). The combined organic layer was dried over MgSO 4 and concentrated in vacuo to give the reaction product, which typically did not require further purification.
EXAMPLE 7
Method A: Synthesis of 2-(2,6-Difluoro-phenyl)-2-(6-arylsulfanyl-pyridazin-3-yl)-acetamide Using Sodium Hydride as Base
[0152] [0152]
[0153] To a stirred suspension of sodium hydride (1.3 eq.) in anhydrous THF (approximately 200 mL/g) at room temperature under N 2 was added dropwise a solution of the appropriate thiophenol (1.3 eq.) in anhydrous THF approximately 50 mL/g). The solution was stirred at room temperature for 30 minutes, after which time a solution of 2-aryl-2-(6-chloro-pyridazin-2,3-yl) acetamide (1 eq.) in anhydrous THF (approximately 50 mL/g) was added. The solution was then heated to 65° C. for 17 hours. The reaction was cooled and saturated aqueous ammonium chloride solution and dichloromethane (DCM; equal volumes, approximately 100 mL/g of 2-aryl-2-(6-chloro-pyridazin-2,3-yl) acetamide used) were added. The organic layer was collected and the aqueous layer re-extracted with DCM (approximately 100 mL/g). The combined organic layer was washed with saturated aqueous brine solution (approximately 100 mL/g), dried over MgSO 4 and concentrated in vacuo to give the crude reaction product, which was typically purified by column chromatography using various ratios of ethyl acetate:hexane as eluant. One having ordinary skill in the art may synthesize analogous compounds, such as compounds comprising a heteroaryl group at R 3 , following the teachings of the specification. In addition, one having ordinary skill in the art may synthesize analogous compounds comprising a substituted amide (a mono- or di-substituted amide) following the teachings of the specification.
[0154] Method B: Synthesis of 2-(2,6-Difluoro-phenyl)-2-(6-alkylsulfanyl-pyridazin-3-yl)-acetamide Using K-Selectride as Base (Fujimoto et al., Tet. Lett., 1999, 40, 5565)
[0155] To a stirred solution of the appropriate thiol (1.1 eq.) in anhydrous DME (approximately 100 mL/g) at 0° C. under N 2 was added dropwise a 1M solution of K-Selectride in THF (1.1 eq.). The solution was stirred at 0° C. for 30 minutes, after which time a solution of 2-aryl-2-(6-chloro-pyridazin-2,3-yl) acetamide (1 eq.) in anhydrous DME (approximately 50 mL/g) was added. The solution was allowed to warm to room temperature and was stirred for 17 hours. A 1M aqueous solution of sodium hydroxide and ethyl acetate (equal volumes, approximately 100 mL/g of 2-aryl-2-(6-chloro-pyridazin-2,3-yl) acetamide used) was added. The organic layer was collected and the aqueous layer re-extracted with ethyl acetate (approximately 100 mL/g). The combined organic layer was washed with saturated aqueous brine solution (approximately 100 mL/g), dried over MgSO 4 and concentrated in vacuo to give the crude reaction product, which was typically purified by column chromatography using various ratios of ethyl acetate:hexane as eluant. One having ordinary skill in the art may synthesize analogous compounds, particularly alkane thiols, following the teachings of the specification. One having ordinary skill in the art may synthesize analogous compounds comprising a substituted amide (a mono- or di-substituted amide) following the teachings of the specification.
EXAMPLE 8
Oxidations of 2-Aryl-2-(6-Thioaryl/Thioalkyl-Pyridazin-2,3-yl) Acetamides
[0156] [0156]
[0157] To a stirred solution of the 2-aryl-2-(6-thiophenyl-pyridazin-2,3-yl) acetamide (1 eq.) in anhydrous DCM (approximately 100 mL/g) at 0° C. under N 2 was added dropwise a solution of m-CPBA (1.1 eq. of approximately 50% w/w) in anhydrous DCM (approximately 50 mL/g). The solution was allowed to warm slowly to room temperature for 17 hours. Saturated aqueous sodium carbonate solution (approximately 100 mL/g of 2-aryl-2-(6-thioaryl/thioalkyl-pyridazin-2,3-yl) acetamide used) was added. The organic layer was removed and the aqueous layer re-extracted with DCM (approximately 100 mL/g). The combined organic layer was dried over MgSO 4 and concentrated in vacuo to give the reaction product, which was not further purified. One having ordinary skill in the art may synthesize analogous compounds following the teachings of the specification.
EXAMPLE 9
Synthesis of p38 Inhibitor Compound 101, (6-(2,6-Difluorophenylamino)-pyridin-3-yl]-phenylmethanone)
[0158] Compound 101 was synthesized according to Example 1 using methyl benzoate as the methoxy arylcarbonyl.
EXAMPLE 10
Cloning of p38 Kinase in Insect Cells
[0159] Two splice variants of human p38 kinase, CSBP1 and CSBP2, have been identified. Specific oligonucleotide primers were used to amplify the coding region of CSBP2 cDNA using a HeLa cell library (Stratagene) as a template. The polymerase chain reaction product was cloned into the pET-15b vector (Novagen). The baculovirus transfer vector, pVL-(His) 6 -p38 was constructed by subcloning a XbaI-BamHI fragment of pET15b-(His) 6 -p38 into the complementary sites in plasmid pVL1392 (Pharmingen).
[0160] The plasmid pVL-(His) 6 -p38 directed the synthesis of a recombinant protein consisting of a 23-residue peptide (MGSSHHHHHHSSGLVPRGSHMLE, where LVPRGS represents a thrombin cleavage site) fused in frame to the N-terminus of p38, as confirmed by DNA sequencing and by N-terminal sequencing of the expressed protein. Monolayer culture of Spodoptera frugiperda (Sf9) insect cells (ATCC) was maintained in TNM-FH medium (Gibco BRL) supplemented with 10% fetal bovine serum in a T-flask at 27° C. Sf9 cells in log phase were co-transfected with linear viral DNA of Autographa califonica nuclear polyhedrosis virus (Pharmingen) and transfer vector pVL(His)6-p38 using Lipofectin (Invitrogen). The individual recombinant baculovirus clones were purified by plaque assay using 1% low melting agarose.
EXAMPLE 11
Expression and Purification of Recombinant p38 Kinase
[0161] [0161] Trichoplusia ni (Tn-368) High-Five™ cells (Invitrogen) were grown in suspension in Excel-405 protein free medium (JRH Bioscience) in a shaker flask at 27° C. Cells at a density of 1.5×10 6 cells/ml were infected with the recombinant baculovirus described above at a multiplicity of infection of 5. The expression level of recombinant p38 was monitored by immunoblotting using a rabbit anti-p38 antibody (Santa Cruz Biotechnology). The cell mass was harvested 72 hours after infection when the expression level of p38 reached its maximum.
[0162] Frozen cell paste from cells expressing the (His) 6 -tagged p38 was thawed in 5 volumes of Buffer A (50 mM NaH 2 PO 4 pH 8.0, 200 mM NaCl, 2 mM β-Mercaptoethanol, 10% Glycerol and 0.2 mM PMSF). After mechanical disruption of the cells in a microfluidizer, the lysate was centrifuged at 30,000× g for 30 minutes. The supernatant was incubated batchwise for 3-5 hours at 4° C. with Talon™ (Clontech) metal affinity resin at a ratio of 1 ml of resin per 2-4 mgs of expected p38. The resin was settled by centrifugation at 500× g for 5 minutes and gently washed batchwise with Buffer A. The resin was slurried and poured into a column (approx. 2.6×5.0 cm) and washed with Buffer A+5 mM imidazole.
[0163] The (His) 6 -p38 was eluted with Buffer A+100 mM imidazole and subsequently dialyzed overnight at 4° C. against 2 liters of Buffer B, (50 mM HEPES, pH 7.5, 25 mM β-glycerophosphate, 5% glycerol, 2 mM DTT). The His 6 tag was removed by addition of at 1.5 units thrombin (Calbiochem) per mg of p38 and incubation at 20° C. for 2-3 hours. The thrombin was quenched by addition of 0.2 mM PMSF and then the entire sample was loaded onto a 2 ml benzamidine agarose (American International Chemical) column.
[0164] The flow through fraction was directly loaded onto a 2.6×5.0 cm Q-Sepharose (Pharmacia) column previously equilibrated in Buffer B+0.2 mM PMSF. The p38 was eluted with a 20 column volume linear gradient to 0.6M NaCl in Buffer B. The eluted protein peak was pooled and dialyzed overnight at 4° C. vs. Buffer C (50 mM HEPES pH 7.5, 5t glycerol, 50 mM NaCl, 2 mM DTT, 0.2 mM PMSF).
[0165] The dialyzed protein was concentrated in a Centriprep (Amicon) to 3-4 ml and applied to a 2.6×100 cm Sephacryl S-100HR (Pharmacia) column. The protein was eluted at a flow rate of 35 ml/hr. The main peak was pooled, adjusted to 20 mM DTT, concentrated to 10-80 mgs/ml and frozen in aliquots at −70° C. or used immediately.
EXAMPLE 12
Activation of p38
[0166] p38 was activated by combining 0.5 mg/ml p38 with 0.005 mg/ml DD-double mutant MKK6 in Buffer B+10 mM MgCl 2 , 2 mM ATP, 0.2 mM Na 2 VO 4 for 30 minutes at 20° C. The activation mixture was then loaded onto a 1.0×10 cm MonoQ column (Pharmacia) and eluted with a linear 20 column volume gradient to 1.0 M NaCl in Buffer B. The activated p38 eluted after the ADP and ATP. The activated p38 peak was pooled and dialyzed against buffer B+0.2 mM Na 2 VO 4 to remove the NaCl. The dialyzed protein was adjusted to 1.1M potassium phosphate by addition of a 4.0M stock solution and loaded onto a 1.0×10 cm HIC (Rainin Hydropore) column previously equilibrated in Buffer D (10% glycerol, 20 mM β-glycerophosphate, 2.0 mM DTT)+1.1MK 2 HPO 4 . The protein was eluted with a 20 column volume linear gradient to Buffer D+50 mM K 2 HPO 4 . The double phosphorylated p38 eluted as the main peak and was pooled for dialysis against Buffer B+0.2 mM Na 2 VO 4 . The activated p38 was stored at −70° C.
EXAMPLE 13
p38 Inhibition Assays
[0167] A. Inhibition of Phosphorylation of EGF Receptor Peptide
[0168] This assay was carried out in the presence of 10 mM MgCl 2 , 25 mM β-glycerophosphate, 10% glycerol and 100 mM HEPES buffer at pH 7.6. For a typical IC 50 determination, a stock solution was prepared containing all of the above components and activated p38 (5 nM). The stock solution was aliquotted into vials. A fixed volume of DMSO or inhibitor in DMSO (final concentration of DMSO in reaction was 5%) was introduced to each vial, mixed and incubated for 15 minutes at room temperature. EGF receptor peptide, KRELVEPLTPSGEAPNQALLR, a phosphoryl acceptor in p38-catalyzed kinase reaction (1), was added to each vial to a final concentration of 200 μM. The kinase reaction was initiated with ATP (100 μM) and the vials were incubated at 30° C. After 30 minutes, the reactions were quenched with equal volume of 10% trifluoroacetic acid (TFA).
[0169] The phosphorylated peptide was quantified by HPLC analysis. Separation of phosphorylated peptide from the unphosphorylated peptide was achieved on a reverse phase column (Deltapak, 5 μm, C 1-8 100D, Part no. 011795) with a binary gradient of water and acteonitrile, each containing 0.1% TFA. IC 50 (concentration of inhibitor yielding 50% inhibition) was determined by plotting the percent (%) activity remaining against inhibitor concentration.
[0170] B. Inhibition of ATPase Activity
[0171] This assay is carried out in the presence of 10 mM MgCl 2 , 25 mM β-glycerophosphate, 10% glycerol and 100 mM HEPES buffer at pH 7.6. For a typical Ki determination, the Km for ATP in the ATPase activity of activated p38 reaction is determined in the absence of inhibitor and in the presence of two concentrations of inhibitor. A stock solution is prepared containing all of the above components and activated p38 (60 nM). The stock solution is aliquotted into vials. A fixed volume of DMSO or inhibitor in DMSO (final concentration of DMSO in reaction was 2.5%) is introduced to each vial, mixed and incubated for 15 minutes at room temperature. The reaction is initiated by adding various concentrations of ATP and then incubated at 30° C. After 30 minutes, the reactions are quenched with 50 μl of EDTA (0.1 M, final concentration), pH 8.0. The product of p38 ATPase activity, ADP, is quantified by HPLC analysis.
[0172] Separation of ADP from ATP is achieved on a reversed phase column (Supelcosil, LC-18, 3 μm, part no. 5-8985) using a binary solvent gradient of following composition: Solvent A-0.1 M phosphate buffer containing 8 mM tetrabutylammonium hydrogen sulfate (Sigma Chemical Co., catalogue no. T-7158), Solvent B-Solvent A with 30% methanol.
[0173] Ki is determined from the rate data as a function of inhibitor and ATP concentrations.
[0174] p38 inhibitors of this invention will inhibit the ATPase activity of p38.
[0175] The p38 inhibitory activity of certain compounds of this invention are shown in Table 7. For p38 kinase IC 50 values, “+++” represents≦1 μM, “++” represents between 1.0 and 10 μM, and “+” represents≧10 μM. For p38 kinase K i values, “+++” represents≦1 μM, “++” represents between 1.0 and 10 μM, and “+” represents≧10 μM.
TABLE 7 Cpd. p38 IC 50 p38 K i No. (μM) (μM) 101 +++ ND 102 +++ ND 103 ++ ND 104 +++ ND 105 +++ ND 106 +++ ND 107 +++ ND 108 +++ ND 109 + ND 110 +++ ND 111 ++ ND 112 +++ ND 113 +++ ND 114 +++ ND 115 +++ ND 116 +++ ND 117 +++ ND 118 ++ ND 119 +++ ND 120 ++ ND 201 +++ ND 301 ++ ND 401 + ND 402 + ND 501 + ND 502 + ND 503 +++ ND 601 ++ ND 602 ++ ND 603 ++ ND 604 +++ ND 605 +++ ND 606 + ND 607 +++ ND 608 ++ ND 609 ++ ND 610 +++ ND 611 +++ ND 612 + ND 613 +++ ND 614 +++ ND 615 + ND 616 + ND 617 ++ ND 618 ++ ND 619 +++ ND 620 +++ ND 621 ++ ND 622 +++ ND 623 +++ ND 624 +++ ND 625 ND ++ 626 ND ++ 627 ND ++ 628 ND ++ 629 ND ++ 630 ND ++ 631 ND ++ 632 ND ++ 633 ND ++ 634 ND ++ 635 ND ++
[0176] C. Inhibition of IL-1, TNF, IL-6 and IL-8 Production in LPS-Stimulated PBMCs
[0177] Inhibitors were serially diluted in DMSO from a 20 mM stock. At least 6 serial dilutions were prepared. Then 4× inhibitor stocks were prepared by adding 4 μl of an inhibitor dilution to 1 ml of RPMI1640 medium/10% fetal bovine serum. The 4× inhibitor stocks contained inhibitor at concentrations of 80 μM, 32 μM, 12.8 μM, 5.12 μM, 2.048 μM, 0.819 μM, 0.328 μM, 0.131 μM, 0.052 μM, 0.021 μM etc. The 4× inhibitor stocks were pre-warmed at 37° C. until use.
[0178] Fresh human blood buffy cells were separated from other cells in a Vacutainer CPT from Becton & Dickinson (containing 4 ml blood and enough DPBS without Mg 2+ /Ca 2+ to fill the tube) by centrifugation at 1500× g for 15 min. Peripheral blood mononuclear cells (PBMCs), located on top of the gradient in the Vacutainer, were removed and washed twice with RPMI1640 medium/10% fetal bovine serum. PBMCs were collected by centrifugation at 500× g for 10 min. The total cell number was determined using a Neubauer Cell Chamber and the cells were adjusted to a concentration of 4.8×10 6 cells/ml in cell culture medium (RPMI1640 supplemented with 10% fetal bovine serum).
[0179] Alternatively, whole blood containing an anti-coagulant was used directly in the assay.
[0180] 100 μl of cell suspension or whole blood were placed in each well of a 96-well cell culture plate. Then 50 μl of the 4× inhibitor stock was added to the cells. Finally, 50 μl of a lipopolysaccharide (LPS) working stock solution (16 ng/ml in cell culture medium) was added to give a final concentration of 4 ng/ml LPS in the assay. The total assay volume of the vehicle control was also adjusted to 200 μl by adding 50 μl cell culture medium. The PBMC cells or whole blood were then incubated overnight (for 12-15 hours) at 37° C./5% CO 2 in a humidified atmosphere.
[0181] The next day the cells were mixed on a shaker for 3-5 minutes before centrifugation at 500× g for 5 minutes. Cell culture supernatants were harvested and analyzed by ELISA for levels of IL-1□ (R & D Systems, Quantikine kits, #DBL50), TNF-□ (BioSource, #KHC3012), IL-6 (Endogen, #EH2-IL6) and IL-8 (Endogen, #EH2-IL8) according to the instructions of the manufacturer. The ELISA data were used to generate dose-response curves from which IC 50 values were derived.
[0182] The p38 inhibitors of this invention will also inhibit phosphorylation of EGF receptor peptide, and will inhibit the production of IL-1, TNF and IL-6, as well as IL-8, in LPS-stimulated PBMCs or in whole blood.
[0183] D. Inhibition of IL-6 and IL-8 Production in IL-1-Stimulated PBMCs
[0184] This assay is carried out on PBMCs exactly the same as above except that 50 μl of an IL-1b working stock solution (2 ng/ml in cell culture medium) is added to the assay instead of the (LPS) working stock solution.
[0185] Cell culture supernatants are harvested as described above and analyzed by ELISA for levels of IL-6 (Endogen, #EH2-IL6) and IL-8 (Endogen, #EH2-IL8) according to the instructions of the manufacturer. The ELISA data are used to generate dose-response curves from which IC 50 values were derived.
[0186] E. Inhibition of LPS-Induced Prostaglandin Endoperoxide Synthase-2 (PGHS-2, or COX-2) Induction in PBMCs
[0187] Human peripheral mononuclear cells (PBMCs) are isolated from fresh human blood buffy coats by centrifugation in a Vacutainer CPT (Becton & Dickinson). 15×10 6 cells are seeded in a 6-well tissue culture dish containing RPMI 1640 supplemented with 10% fetal bovine serum, 50 U/ml penicillin, 50 μg/ml streptomycin, and 2 mM L-glutamine. Compounds are added at 0.2, 2.0 and 20 μM final concentrations in DMSO. LPS is then added at a final concentration of 4 ng/ml to induce enzyme expression. The final culture volume is 10 ml/well.
[0188] After overnight incubation at 37° C., 5% CO 2 , the cells are harvested by scraping and subsequent centrifugation, the supernatant is removed, and the cells are washed twice in ice-cold DPBS (Dulbecco's phosphate buffered saline, BioWhittaker). The cells are lysed on ice for 10 min in 50 μl cold lysis buffer (20 mM Tris-HCl, pH 7.2, 150 mM NaCl, 1% Triton-X-100, 1% deoxycholic acid, 0.1% SDS, 1 mM EDTA, 2% aprotinin (Sigma), 10 μg/ml pepstatin, 10 μg/ml leupeptin, 2 mM PMSF, 1 mM benzamidine, 1 mM DTT) containing 1 μl Benzonase (DNAse from Merck). The protein concentration of each sample is determined using the BCA assay (Pierce) and bovine serum albumin as a standard. Then the protein concentration of each sample is adjusted to 1 mg/ml with cold lysis buffer. To 100 μl lysate an equal volume of 2× SDS PAGE loading buffer is added and the sample is boiled for 5 min. Proteins (30 μg/lane) are size-fractionated on 4-20% SDS PAGE gradient gels (Novex) and subsequently transferred onto nitrocellulose membrane by electrophoretic means for 2 hours at 100 mA in Towbin transfer buffer (25 mM Tris, 192 mM glycine) containing 20% methanol. After transfer, the membrane is pretreated for 1 hour at room temperature with blocking buffer (5% non-fat dry milk in DPBS supplemented with 0.1% Tween-20) and washed 3 times in DPBS/0.1% Tween-20. The membrane is incubated overnight at 4° C. with a 1: 250 dilution of monoclonal anti-COX-2 antibody (Transduction Laboratories) in blocking buffer. After 3 washes in DPBS/0.1% Tween-20, the membrane is incubated with a 1:1000 dilution of horseradish peroxidase-conjugated sheep antiserum to mouse Ig (Amersham) in blocking buffer for 1 h at room temperature. Then the membrane is washed again 3 times in DPBS/0.1% Tween-20. An ECL detection system (SuperSignal™ CL-HRP Substrate System, Pierce) is used to determine the levels of expression of COX-2.
[0189] While we have hereinbefore presented a number of embodiments of this invention, it is apparent that our basic construction can be altered to provide other embodiments which utilize the methods of this invention
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The present invention relates to inhibitors of p38, a mammalian protein kinase involved cell proliferation, cell death and response to extracellular stimuli. The invention also relates to methods for producing these inhibitors. The invention also provides pharmaceutical compositions comprising the inhibitors of the invention and methods of utilizing those compositions in the treatment and prevention of various disorders.
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This is a Divisional application of Ser. No. 07/945,909 filed Sep. 17, 1992.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resist composition and a process for forming a resist pattern.
More particularly, the present invention relates to a resist composition containing a certain copolymer and a photo acid generator and also relates to the process for forming the resist pattern having a high sensitivity and a good dry etch resistance.
2. Description of the Related Art
Due to the necessity of treating a large amount of information at a high speed on an integrated semiconductor device, which plays a main role in an information treating device, large-scale integrated circuits (LSI) and very large-scale integrated circuits (VLSI) have been developed and are now in practice.
This integration is carried out by the miniaturization of unit elements such as wiring patterns and electrodes. At present, the use of submicron minimum line spacing in the wiring pattern is common.
When forming a fine resist pattern, ultraviolet lights were employed as an exposure light source at the beginning of the photolithography. Due to limitations in the use of wavelength, an exposure process using deep ultraviolet lights are carried out.
Here, the exposure light source that radiates deep ultraviolet lights as mentioned can be a high pressure mercury lamp or an excimer laser.
However, there is the problem that the power of the high pressure mercury lamp is low, in the wavelength region of the deep ultraviolet light.
Therefore, the use of a large power excimer laser (for instance, when KrF is used, the wavelength is 248 nm) has been considered as the exposure light source.
However, even if the excimer laser is employed, the prior resist composition cannot be used, because said resist absorbs too much deep ultraviolet light, so that the said resist results in sloped wall profiles and poor resolution.
Therefore, practical use of such a resist composition having a high resolution and capable of being applied to the above wavelength light is desired.
In the conventional resist composition, many kinds of resists containing an aromatic ring (such as a benzene ring) so as to obtain good dry etch resistance, for instance, a phenol novolak resin, have been developed as a base polymer.
However, the resist containing an aromatic ring absorbs far too much deep ultraviolet light, so that a fine pattern corresponding to miniaturization in the patterning process using deep ultraviolet lights as an exposure light source cannot be obtained.
On the other hand, as a KrF excimer resist, the resist including an acrylate polymer such as poly t-butylmetacrylate as a base polymer has been studied but, it was found that said polymer did not display good dry etch resistance because of the lack of the aromatic ring.
Therefore, practical use of such a resist composition having good dry etch resistance and good transparency, in which the polymer lacks an aromatic ring is strongly desired.
The necessary requirements for the resist that can be adopted for use in the region of an deep ultraviolet light are as follows:
1) Minimal absorption in the region of deep ultraviolet lights and having a high resolution;
2) High sensitivity; and
3) Superiority in dry etch resistance.
However, a resist fully satisfying the above requirements has not yet been developed.
Therefore, there is a need to develop a resist that satisfies the above requirements and to apply said resist.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide a new chemically amplified resist composition that is effective in forming a fine pattern in the process of the production of the semiconductor.
It is another object of the present invention to provide a process of forming a resist pattern using the above resist composition.
Namely, the first mentioned object can be attained by the present chemically amplified resist composition that comprises:
100 parts by weight of a copolymer consisting of a 2-norbornene-2-substituent unit and an acrylic acid ester unit of the formula I; ##STR2## wherein, X is a cyano or chloro group, R is tert-butyl, dimethylbenzyl, or tetrahydropyranyl, m is an integer of 9 to 2390, and n is an integer of 21 to 5180, and 1 to parts by weight of a photo acid generator.
The second mentioned object can be attained by the present process for forming a resist pattern that comprises the steps of:
coating a substrate to be fabricated with a resist composition comprising 100 parts by weight of a copolymer consisting of a 2-norbornene-2-substituent unit and an acrylic acid ester unit of the formula I; ##STR3## wherein, X is a cyano or chloro group, R is tert-butyl, dimethylbenzyl, or tetrahydropyranyl, m is an integer of 9 to 2380, and n is an integer of 21 to 5180, and 1 to 20 parts by weight of a photo acid generator,
drying the resist composition to form a resist coating,
exposing the resist coating selectively to a predetermined pattern of radiation to form a latent image in the resist layer corresponding to the radiation pattern, and
baking the resist coating, followed by developing the pattern-wise exposed resist coating with a developer to form a resist pattern.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The above-mentioned problems can be solved by the present resist composition and a process for forming a resist pattern.
The present inventors carried out experiments with the hope of finding a new polymer having superior dry etch resistance properties and a greater sensitivity than that of the conventional resist.
As a result of the experiments, the present inventors discovered the new copolymer consisting of a 2-norbornene-2-substituent unit and acrylic acid ester unit, as a base polymer for the chemically amplified resist.
Namely, the present inventors selected the monomer unit, 2-norbornene-2-substituent, as a material providing good dry etch resistance. The above unit is an aliphatic hydrocarbon and works as resistant groups in dry etching in the same way as aromatic rings, and also does not absorb light at deep ultraviolet wavelengths because of the lack of aromatic rings.
Therefore, the present inventors selected a copolymer consisting of a 2-norbornene-2-substituent unit having no capacity for absorbing deep ultraviolet light and an acrylic acid ester unit having no capacity for absorbing deep ultraviolet light as a base polymer to satisfy the requirements of the above 1) and 3). Furthermore, the present inventors added the photo acid generator (in short PAG) to the above-mentioned copolymer to form a chemically amplified resist that provides high sensitivity and fulfills the above-mentioned three requirements 1) and 3).
The chemically amplified resist was proposed by IBM (U.S. Pat. No. 4,491,628). This type of resist attempts to realize high-sensitivity and high resolution by employing the PAG, which generates Strong Broensted acids by means of exposure.
Namely, the PAG is added to the polymer to obtain a chemically amplified resist. The characteristics of this resist are such that the Broensted acid generated from the PAG by light-exposure acts on the polymer as a catalyst by means of post-baking (heating) carried out after said exposure, and causes the successive elimination reaction of the protecting group as well as a change in polarization.
Therefore, this type of the resist can provide a positive-working pattern in fine resolution by developing same in an alkaline solution.
Next, the reaction proceeds as shown in the following formula II, when the present resist is exposed to ultraviolet lights: ##STR4##
As shown above, the esters moiety in the acrylate unit in the exposure areas changes to carboxylic acids that can be dissolved in an alkaline solution.
As mentioned above, the present invention can utilize the change of polarity of the polymer to effect patterning, so that a non-swelling pattern can be obtained. Furthermore, the present base polymer consists of the copolymer of an acrylate monomer unit and an alicyclic monomer unit, so that the present resist is highly transparent and can provide a finely-figured pattern. And also, the above-mentioned reaction (2) is a type of amplification in which proton regenerates, so that the resist is highly sensitive.
In the present composition, the following compounds can be employed as the PAG:
a diaryl indonium salt such as ##STR5## and ##STR6## and an aryl sulfonium salt, for example, triaryl sulfonium salts such as ##STR7## and ##STR8## sulfonic acid derivatives, for example, sulfonic acid esters such as ##STR9## and halogen-containing compounds such as ##STR10##
The PAG can be used in a ratio of 1 to 20 parts by weight based on 100 parts by weight of the polymer in the present composition. When less than 1 part by weight of the PAG is used in the composition, the expected reaction does not proceed, while, when more than 20 parts by weight of the PAG is used, the transparency and resolution of the resist is poor.
The process of the present invention is valuable for the formation of either a positive-working resist pattern or a negative-working resist pattern. When a negative-working pattern is expected to be obtained, a nonpolar organic solvent is usually used as a developer, and when a positive-working pattern is expected to be obtained, a polar organic solvent or an alkaline aqueous solution such as tetramethyl ammonium hydroxide (TMAH) and 2-hydroxyethyl trimethyl ammonium hydroxide (choline) is usually used as a developer. Moreover, the resist material to be used in the present invention can have a sensitivity to light from various light sources, and in the instant specification, the word "light" or "radiation" is used in a broad sense, and a variety of light sources ranging from high-energy radiation light such as electron beams and ion beams to X-rays and deep ultraviolet light can be used.
In the present invention, the preferred light source is an excimer laser.
Also, in the present invention, a drying process is effected at room temperature or under baking conditions to vaporize the solvent in the resist composition coating.
Also, in the present invention, a baking process is preferably carried out at a temperature of about 60° C. to about 120° C. to accelerate the reaction of the present copolymer with a photo acid generator expressed by the above-mentioned formula II.
If the temperature in the post exposure baking process is less than about 60° C., the sensitivity of the obtained resist pattern is low. On the other hand, if the temperature is over about 120° C., the above reaction of the formula II proceeds too fast.
The invention will be more clearly understood with reference to the following examples. It is to be expressly understood, however, that the examples are for the purpose of illustration only and are not intended as a definition of the limits of the invention.
EXAMPLES
Synthetic Example 1 (Synthesis of copolymer of 2-norbornene-2-carbonitrile and methacrylic acid tetrahydropyranyl ester)
5.0 g (41.6 m mol) of 2-norbornene-2-carbonitrile, 4.72 g (27.7 m mole) of methacrylic acid tetrahydropyranyl ester and 13.9 ml of tetrahydrofuran (fully dried) (in short THF) were charged into 100 ml of the three-necked flask equipped with a magnetic stirring bar coated with a fluorine polymer (Teflon, which is a registered mark), followed by stirring at -17° C. for ten minutes under a nitrogen atmosphere.
To this solution, 311 mg (2.8 m mol, 4 mol %) of potassium tert-butoxide was dissolved and 4 ml of dry THF was slowly added dropwise by means of a syringe.
Next, the solution which was prepared by dissolving 740 mg (2.8 m mol) of 18-crown-6 and 2 ml of THF was slowly added dropwise to the above solution by means of a syringe while maintaining the temperature of the reaction system, and then stirring for 1.5 hours.
Next, the reaction system was allowed to stand at room temperature, followed by stirring for 4 hours and the reaction was stopped by adding 10 ml of THF (commercial grade).
1.5 l of methanol was added to the reaction solution to form precipitates, then the thus obtained precipitates were filtered off through a glass filter (3G), then dried under 0.1 mm Hg at 40° C. for 6 hours to form white powder.
The obtained powder was dissolved in 30 ml of THF, followed by repreciptating the solution using 1.5 1 of methanol.
Next, the obtained white precipitates were filtered off through a glass filter (3G), then dried under 0.1 mm Hg at 40° C. for 16 hours to form white powder.
The obtained copolymer yielded 3.35 g (34.5%), the average molecular weight of the copolymer is 32000, the degree of dispersion is 1.73 and the rate of copolymerization of norbornene to methacrylate is 36 to 64.
Incidentally, the starting monomer of 2-norbornene-2-carbonitrile can be obtained by the following steps: ##STR11##
Synthetic Example 2 (Synthesis of copolymer of 2-norbornene-2-carbonitrile and methacrylic acid t-butyl ester)
7.5 g (62.4 m mol) of 2-norbornene-2-carbonitrile, 5.91 g (41.6 m mole) of methacrylic acid t-butyl ester and 20.8 ml of tetrahydrofuran (fully dried) (in short THF) were charged into 100 ml of the three-necked flask equipped with a magnetic stirrer coated with a fluorine polymer (Teflon, which is a registered mark), followed by stirring at -17° C. for ten minutes under a nitrogen atmosphere.
To this solution, 467 mg (4.2 m mol, 4 mol %) of potassium tert-butoxide was dissolved and 5 ml of dry THF were slowly added dropwise by means of a syringe while maintaining the temperature of the reaction system.
Next, the system was stirred at -17° C. for 0.5 hours, and the reaction was stopped by adding 50 ml of THF (commercial grade).
2.0 l of methanol was added to the reaction solution to form precipitates, then the obtained precipitates were filtered off through a glass filter (3G), and dried under 0.1 mm Hg at 60° C. for 6 hours to form yellow powder.
The obtained powder was dissolved in 100 ml of THF, followed by reprecipitation of the solution by using 2.0 l of methanol.
Next, the obtained white precipitates were filtered off through a glass filter (3G), then dried under 0.1 mm Hg at 60° C. for 16 hours to form white powder.
The obtained copolymer yielded 7.82 g (58.3%), the average molecular weight of the copolymer is 17000, the degree of dispersion is 1.57 and the rate of copolymerization of norbornene to methacrylate is 59 to 41.
Example 1
10% by weight of benzoin tosylate used as PAG was added to the copolymer of 2-norbornene-2-carbonitrile and methacrylic acid tetrahydropyranyl ester (copolymerization ratio, 36:64) prepared by the procedure described in Synthetic Example 1, and was dissolved in a cyclohexane solution to prepare 20% by weight of a solution as a resist composition.
The obtained resist composition was spin-coated on a Si-wafer, then heated for 20 minutes at a temperature of 100° C. to dry the resist and obtain a resist coating having a thickness of 1 μm.
This coating was exposed to a predetermined pattern of radiation to form a latent image by using a KrF excimer laser, then baked at 100° C. for 60 seconds and developed in an aqueous solution of 2.38% tetramethyl ammonium hydroxide (TMAH) for one minute to obtain a positive resist pattern.
The transmittance of the resist coating at 248 nm of the wavelength was 66%/μm, and the sensitivity therefor was 1.0 mJ/cm 2 . And also, 0.4 μm lines-and-spaces were resolved.
Next, the resist coating was set in the dry-etching apparatus, and etched using of CF 4 /O 2 (Flow rate: 0.95/0.05) as an etching gas, 0.3 torr, and 300 W. The etching rate of the resist in Example 1 was found to be 970 Å/min, which is superior to that of the NPR-820 resist (supplied by Nagase Sangyo Co., Ltd.) which has an etching rate of 980 Å/min. Therefore, it is found that the present resist composition has better dry etch resistance than those of the conventional Novolak resist.
Example 2
10% by weight of triphenylsulphonium hexafluoroantimonate used as PAG was added to the copolymer of 2-norbornene-2-carbonitrile and methacrylic acid t-butyl ester (copolymerization ratio, 59:41) prepared by the procedure described in Synthetic Example 2, followed by dissolving same in a cyclohexane solution to prepare 16% by weight of a solution as a resist composition.
The obtained resist composition was spin-coated on a Si-wafer, then heated at 100° C. for 20 minutes to dry the resist and obtain a resist coating having a thickness of 1 μm.
This coating was exposed to a predetermined pattern of radiation so as to form a latent image by using a KrF excimer laser, then post-exposure baked at 100° C. for 60 seconds and developed in an aqueous solution of 2.38% tetramethyl ammonium hydroxide (TMAH) for one minute to obtain a positive resist pattern.
The transmission of the resist coating at 248 nm of the wavelength was 62%/μm, and the sensitivity therefor was 10 mJ/cm 2 . And also, 0.4 μm lines-and-spaces were resolved.
Next, the resist coating was set in the dry-etching apparatus, and etched using CF 4 /O 2 (Flow rate: 0.95/0.05) as an etching gas, 0.3 torr and 300 W. The etching rate for the resist in Example 1 was found to be 892 Å/min, which is superior to that of the NPR-820 resist (supplied by Nagase Sangyo Co., Ltd.) which has an etching rate of 980 Å/min. Therefore, it is found that the present resist composition has better dry etch resistance than those of the conventional Novolak resist.
Example 3
10% by weight of p-toluene suphonic acid phenyl ester used as PAG was added to the copolymer of 2-norbornene-2-carbonitrile and methacrylic acid t-butyl ester (copolymerization ratio, 59:41) prepared by the procedure described in Synthetic Example 2, followed by dissolving same in a cyclohexane solution to prepare 16% by weight of a solution as a resist composition.
The obtained resist composition was spin-coated on a Si-wafer, then heated for 20 minutes at a temperature of 100° C. to dry the resist and obtain a resist coating having a thickness of 1 μm.
This coating was exposed to a predetermined pattern of radiation to form a latent image by using a KrF excimer laser, then heated for 60 seconds at a temperature of 100° C. and developed in an aqueous solution of 2.38% tetramethyl ammonium hydroxide (TMAH) for one minute to obtain a positive resist pattern.
The transmission of the resist coating at 248 nm of the wavelength was 67%/μm, and the sensitivity therefor was 10 mJ/cm 2 . 0.4 μm in a lines-and-spaces were resolved.
Next, the resist coating was set in the dry-etching apparatus, and etched using of CF 4 /O 2 (Flow rate: 0.95/0.05) as an etching gas., 0.3 torr, and 300 W. The etching rate for the resist in Example 1 was found to be 892 Å/min, which is superior to that of the NPR-820 resist (supplied by Nagase Sangyo Co., Ltd.) which has an etching rate of 980 Å/min. Therefore, it is found that the present resist composition has better dry etch resistance than those of the conventional Novolak resist.
The above descriptions are the result of an excimer laser being employed as an exposure light source, however, other exposure lights sources such as X-rays and electron beams could be employed in the present process and a finely-resolved pattern could be obtained.
As the present composition is constructed as described in the specification, the present resist composition can provide good dry etch resistance, highly sensitive, and highly resolved resist coating. Hence, the present composition ensures the formation of a finely resolved pattern.
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A resist composition and a process for forming a resist pattern using a resist composition are disclosed. The present composition includes 100 parts by weight of a copolymer of a 2-norbornene-2-substituent unit and an acrylic acid ester unit of the formula I; ##STR1## wherein, X is a cyano or chloro group, R is tert-butyl, dimethylbenzyl, or tetrahydropyranyl, m is an integer of 9 to 2390, and n is an integer of 21 to 5180, and 1 to 20 parts by weight of a photo acid generator. A finely-resolved resist pattern with high sensitivity and good dry etch resistance is obtained by the present composition and present process for forming the resist pattern.
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FIELD OF THE INVENTION
[0001] The present invention pertains to a medical device used to extract foreign objects from a patient. More specifically, the invention relates to an endoscopic device used to retrieve, crush, and remove gallstones and the like. The device is designed to traverse through narrow passages within the body and to open within those passages to retrieve the foreign object.
BACKGROUND OF THE INVENTION
[0002] The removal of foreign bodies from patients often requires the use of endoscopic devices. In particular, gastroenterologists commonly use grasping or crushing devices to extract stones from a patient's biliary duct. Additionally, snares are often used when removing stents or other foreign objects.
[0003] Grasping and crushing devices generally take the form of wire baskets that deploy to capture the stone to be extracted. These wire baskets may be used for lithotripsy if the stone is too large to be removed intact. Lithotripsy involves crushing the stone into fragments to facilitate removal from the duct. Effective performance of such devices requires the baskets to have enough flexibility to be inserted into the common bile duct. However, the baskets also must have a certain degree of rigidity to dilate the duct to facilitate stone capture. Often, the baskets are deployed using a retaining cannula. In this case, the cannula retains the basket in a retracted configuration during insertion into the bile duct. Once within the grasping region of a stone, the basket extends from the cannula and opens to capture the stone. In such a case, the basket must have enough stiffness to open the duct when removed from the cannula, without being so stiff that it is permanently deformed due to retention within the cannula.
[0004] Aside from deformation associated with dilating the duct or retention within the cannula, a common failure of conventional baskets occurs during lithotripsy when the baskets are subject to forces often in excess of 50 pounds. Under such force, the basket can become severely deformed, rendering it unsuitable for repeated use. Such repeated use is desirable because of the frequent occurrence of the need to remove more than one stone or other object at a time from the patient. Therefore, design of these devices includes focus on the durability of the basket in repeated use settings.
[0005] To repeatedly crush and retrieve foreign objects, a basket must be flexible enough to traverse tortuous anatomy, yet stiff enough to open within a duct, and strong enough to crush stones. A single wire construction may meet any one of these criteria, but typically cannot meet all three requirements for repeated dilation and lithotripsy. It has been proposed, therefore, to construct a retrieval basket of a stranded cable, such as stainless steel cable. Purely stainless steel cable (the core and strands) may work well for the extraction of a single stone, but is subject to the deformation problems discussed previously when used for repeated dilatation or lithotripsy.
[0006] Other baskets are formed from cable which includes a superelastic, sometimes referred to as shape memory, core wrapped with strands of stainless steel to surround the core. Nitinol is often used as the superelastic core in these devices. Nitinol is a specially heat-treated Titanium-Nickel (Ti-Ni) alloy, preferably approximately 55%/45% Nickel to Titanium (Ni-Ti). These baskets require heat treatment for the core to retain its shape. Such a configuration allows for some improvement in performance when the baskets are used repeatedly and for lithotripsy because the superelastic core better retains its shape.
[0007] However, superelastic materials of this type experience phase transformations when subject to a certain level of stress loading. Lithotripsy often reaches these stress levels. Upon a phase transformation, the core of the cable stretches, rendering the device incapable of transferring force to the stone to complete the crushing process. Furthermore, the superelastic alloy has a greater reversible elongation than do the surrounding stainless steel strands. This results in a difference in deformation between the core and the surrounding strands leading to a permanent deformation of the cable. Such deformation results in an alteration of the basket shape, making it less desirable to use for its intended purpose.
[0008] Moreover, manufacturing both the cable core and strands from superelastic alloy wires results in a cable that unwinds due to the highly elastic nature of the material. Thus, a retrieval basket of such cable also will not retain its desired shape without heat treating.
SUMMARY OF THE INVENTION
[0009] The advantages and purpose of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purpose of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
[0010] To attain the advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention includes a medical retrieval device for retrieving foreign objects from within a patient's body. The retrieval device includes a retrieval assembly containing a cable preformed into a configuration for capturing and removing the foreign object. The retrieval cable includes wire made of a precursor alloy to a superelastic material. According to a particularly preferred embodiment of the invention, the cable includes a core wire and surrounding wire strands, each made of the precursor alloy.
[0011] The invention further includes a method of manufacturing the medical retrieval device including the steps of constructing a cable including a wire made of a precursor alloy to a superelastic material and forming a retrieval assembly by preforming the cable into a configuration adapted to capture and remove the foreign objects.
[0012] The precursor alloy according to the present invention exhibits a stress-strain curve having a linear relationship extending through a yield point with no phase transformation point. After the yield point, the stress-strain curve does not exhibit a substantially constant stress plateau as strain increases. Rather, the precursor alloy exhibits plastic deformation properties.
[0013] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the preferred embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,
[0015] [0015]FIG. 1 a is a stress-strain curve for a superelastic alloy;
[0016] [0016]FIG. 1 b is a stress-strain curve for a precursor alloy;
[0017] [0017]FIG. 2 a is a cross-sectional view of one embodiment of a stranding configuration according to the present invention, wherein a core of precursor alloy is surrounded by strands of stainless steel wires;
[0018] [0018]FIG. 2 b is a cross-sectional view of another embodiment of a stranding configuration according to the present invention, wherein a core of precursor alloy is surrounded by strands of precursor alloy wire; and
[0019] [0019]FIG. 3 is a wire basket retrieval device according to an embodiment of the present invention and in a deployed position for retrieving an object.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] The various aspects of this invention generally pertain to a device, and a method for manufacturing such a device, for retrieving foreign objects in a body from locations requiring traversal of narrow passages. In use, such a device must be able to collapse into a relatively narrow space for traversal purposes and to expand in that space for retrieval purposes. The device also must have strength characteristics so that the device can crush objects to facilitate capturing and removal. Additionally, the device must reconfigure to it original shape when expanded and retain its ability to reconfigure to the original shape for repeated deployments without losing strength and without suffering permanent deformation.
[0021] To accomplish these objectives and to overcome the problems associated with existing devices of this kind, a retrieval device of the present invention incorporates a precursor alloy into the stranded cable used for making the device. When subject to heat treatment, a precursor alloy results in the formation of a superelastic alloy. Prior to heat treatment, such a precursor alloy exhibits high elongation and a linear stress-strain relationship with a yield point. Because of these properties, the use of a precursor alloy in the manufacture of the device according to the present invention achieves greater strength, longer life, and ease in manufacture, as will be explained.
[0022] Unlike a superelastic alloy, a precursor alloy used in a medical retrieval device of the present invention exhibits a linear stress-strain relationship with a plastic yield point. For comparison purposes, schematics of the stress-strain curves for a superelastic alloy and a precursor alloy are shown in FIGS. 1 a and 1 b , respectively. As shown in FIG. 1 a , as a superelastic alloy undergoes increased stress, strain increases to phase transformation point X. At X, the superelastic alloy transforms from an austenitic phase to a martensitic phase. Thereafter, stress remains substantially constant as strain increases, forming a substantially constant stress plateau P. Upon releasing the stress on the superelastic alloy, the reversibly deformable nature of the material allows it to return to its original length following curve Y in the Figure. The cycle shown often occurs repeatedly with no appreciable change in dimension or plastic deformation of the wire. Therefore, the superelastic alloy withstands a relatively large strain prior to the phase transformation point, and additional strain during the phase transformation, without plastic deformation. Furthermore, the phase transformation and reversible deformation of the superelastic alloy occurs at relatively low stress levels. During the superelastic alloy phase transformation, applied stress is absorbed by the alloy to facilitate the phase transformation, and is not available to be transferred to another object, such as a stone.
[0023] A precursor alloy material exhibits the stress-strain characteristics shown in FIG. 1 b . Up to the plastic yield point Z, strain increases in a reversible manner as stress increases. That is, the precursor alloy returns to its normal configuration upon release of stresses prior to reaching plastic yield point Z. Moreover, the precursor alloy does not pass through a substantially constant stress plateau as does the superelastic alloy. At stresses above yield point Z, the precursor alloy becomes plastically and irreversibly deformed, unlike the superelastic alloy. As shown in FIGS. 1 a and 1 b , yield point Z of the precursor alloy generally occurs at higher stress levels than does phase transformation point X of the superelastic material. This enables the device of the present invention to transfer greater stress to stones during lithotripsy, as well as facilitating dilation of ducts. Accordingly, the inventive devices facilitate retrieval and removal, while maintaining shape and strength over repeated uses.
[0024] In addition to requiring heat treatment of the precursor alloy to produce the superelastic material, a conventional retrieval device also requires heat treatment during the formation of the basket so that the superelastic wires maintain their shape. In contrast, a result of the plastic yield point associated with a precursor alloy, the basket of the present device forms easily by mechanically bending the precursor alloy wire beyond its yield point and into shape. Sophisticated heat treatments are thus unnecessary in the manufacture of the inventive device.
[0025] Moreover, because of the superelastic nature of the heat-treated alloys used in conventional devices, a stranded cable made entirely of a superelastic material is ineffective due to phase transformation deformation and unwinding problems, as mentioned above. However, precursor alloys are highly elastic but also can be plastically deformed. Thus, in a preferred embodiment of the present invention, a cable for a retrieval device is made entirely of a precursor alloy core and precursor alloy strands. It is contemplated that the strands and the core can be made of identical precursor alloy or different precursor alloys. If different precursor alloys are used, it is preferred to select wire dimensions and types such that the wires exhibit similar deformations when subjected to a given load. In either case, the cable will experience neither unwinding nor excessive deformation as would a cable that includes superelastic strands. Furthermore, using a consistent material configuration for both the strands and the core would eliminate problems associated with elongation of the core relative to the surrounding strands leading to permanent damage to the basket. Finally, a cable made entirely of wires of the same precursor alloy material facilitates the manufacturing process.
[0026] Reference will now be made in detail to the present exemplary embodiments of the invention, examples of which are illustrated in FIGS. 2 and 3 . Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
[0027] In accordance with embodiments of the present invention, an endoscopic retrieval device 5 is formed from a stranded cable having the basic configuration shown in either FIG. 2 a or FIG. 2 b . FIG. 2 a shows a cross-section of cable of a first embodiment of the device 5 . A cable 1 includes a core monofilament wire 2 made of precursor alloy. Surrounding core wire 2 are strands 3 of stainless steel wire. Due to the presence of the precursor alloy core wire 2 , device 5 suffers from less deformation problems than does a conventional device of this type that includes a superelastic core. This is because, as previously discussed, precursor alloys exhibit less elongation than do superelastic materials and therefore differences in the elongation between surrounding strands 3 and core wire 2 will be minimized.
[0028] [0028]FIG. 2 b shows a more preferred embodiment of a stranded cable for use in the endoscopic retrieval device 5 . In this embodiment, a cable 1 ′ includes a core wire 2 ′ made of a precursor alloy, as in FIG. 2 a . However, surrounding strands 3 ′ in this embodiment also are formed of precursor alloy, either of identical or different precursor alloy material as core wire 2 ′. As discussed previously, this embodiment is preferred because the cables made entirely of precursor alloy wires (core and strands) will not unwind and are capable of transferring greater stress to objects without deforming. Additionally, cables made of entirely of the same precursor alloy alleviate deformation problems associated with different rates of elongation between the core and strands. When selecting wires of different precursor alloys, it is preferable to impart consistent mechanical properties to the cable. A person having ordinary skill in the art would realize that such consistency can be achieved by varying such factors as, for example, the nature of the alloys of the surrounding strands and core wire, relative dimensions of the core wire and the surrounding strands, the winding pattern of the strands around the core wire, and the post processing of the cable.
[0029] [0029]FIGS. 2 a and 2 b show six surrounding wire strands 3 and 3 ′, respectively. Preferably, there are at least five surrounding wire strands 3 or 3 ′. However, it is contemplated that the number of surrounding strands can be varied in accordance with the particular use for the device or the desired characteristics of the cable.
[0030] In both FIGS. 2 a and 2 b , the precursor alloy is in a martensitic phase at room temperature to body temperature. The precursor alloy can be a precursor Nitinol or other material exhibiting like properties and known to those having ordinary skill in the art. Such other precursor alloys that may be used include, for example, Silver-Cadmium, Gold-Cadmium, Gold-Copper-Zinc, Copper-Zinc, Copper-Zinc-Aluminum, Copper-Zinc-Tin, Copper-Zinc-Xenon, Iron-Beryllium, Iron-Platinum, Indium-Thallium, Iron-Manganese, Nickel-Titanium-Vanadium, Iron-Nickel-Titanium-Cobalt, and Copper-Tin.
[0031] In one preferred form of the invention, the overall diameter of the cable is approximately 0.017 inches. The materials used for the precursor alloy, the number of strands forming the cable, and the overall diameter of the cable can be modified according to the particular use or desired characteristics of the device. The selection of these parameters would be obvious to one having ordinary skill in the art.
[0032] [0032]FIG. 3 shows the overall construction of endoscopic retrieval device 5 . Typically, four cables 1 or 1 ′ form basket 6 . However, any number of cables can be used and would be obvious to one having ordinary skill in the art depending on the use or desired characteristics of the basket. A bullet-shaped nosepiece 7 can be attached to a distal end of device 5 to improve guidance of device 5 during use, as well as to secure cables 1 or 1 ′ to each other. A coupling tube 8 , attached to a proximal end of basket 6 , also facilitates manipulation of device 5 during the retrieval process. Coupling tube 8 also could take the form of a cannula, in which case basket 6 would retract into the cannula prior to retrieval.
[0033] Laser welding represents one preferred mode of attachment of bullet-shaped nosepiece 7 and coupling tube 8 to basket 6 . However, other suitable attachment methods known to those skilled in the art are within the scope of the present invention. Device 5 is used to traverse narrow passages to retrieve, crush, and remove foreign objects within the body. Device 5 can be deployed from a cannula or traverse independently through the body, collapsing and deploying as necessary. Device 5 also may be used repeatedly to retrieve, crush, and remove foreign objects.
[0034] The manufacture of device 5 first involves forming cables 1 , 1 ′. To form these cables, a precursor alloy wire is supplied as the core wire and surrounding strands of wire are placed approximately evenly-spaced around the perimeter of the core wire. Surrounding strands wrap around the core in an essentially helical fashion along its length. The strands can be wrapped clockwise, counterclockwise, or any combination thereof, depending on the desired properties of the cable. A preferred embodiment has strands wrapping clockwise around the core wire, similar to threads of a right-hand screw. The cable can then be rotary swaged, which helps to straighten it and increase its column strength. As discussed with reference to FIGS. 2 a and 2 b , the surrounding strands can be made of stainless steel, or other like, suitable material, or most preferably precursor alloy.
[0035] Several cables, preferably approximately four cables 1 or 1 ′, are then bent past the yield point of either the precursor alloy or stainless steel to form basket 6 . After forming basket 6 , cables 1 or 1 ′ are joined together at one end, through welding or other suitable joining method known to those skilled in the art. Laser welding cables 1 or 1 ′ to coupling tube 8 or, if desired, to the retractable portion of a retaining cannula, represents another method to connect and secure the cables to each other. As discussed with reference to FIG. 3, a nosepiece can be laser welded, or otherwise attached in any suitable manner, to the end of basket 6 to guide device 5 through the body. It is important that during welding or other connecting operations involving heat, that temperature is controlled to prevent heat treating the cable such that the precursor alloys are converted to superelastic materials.
[0036] The stranded cable configuration used in the retrieval device according to the present invention provides the durability necessary to perform lithotripsy and dilation and be repeatedly employed for retrieval processes. Incorporating precursor alloy wire into the cable as opposed to a superelastic material such as Nitinol enables the device to be manufactured without heat treatment processes. Additionally, because precursor alloys do not exhibit the extreme elongation characteristic of superelastic materials, problems of permanent deformation are alleviated when surrounding stainless steel wire strands are used to form the cable. Using precursor alloys also allows for the manufacture of a cable comprised entirely of precursor alloy wire, including the surrounding strands and the core. Whether identical precursor alloy is used for both, or the precursor alloy used for the strands differs from that used for the core, the device will be capable of transferring greater stress to objects without deformation and will not unwind. Additionally, using the same precursor alloy for both the strands and the core facilitates overall manufacture of the device and provides a device of consistent characteristics that will not deform due to disparate elongation properties within the cables.
[0037] Although the use of a basket type retrieval device has been discussed and shown in the Figures, it is contemplated that the device can be of the snare type. A snare made of the precursor alloys discussed above would retain its shape better than conventional stainless steel snare devices. Furthermore, although most of the above discussion pertains to using the inventive device to remove gallstones, it should be appreciated that the devices can be used for removing a variety of other foreign objects having various locations within the body.
[0038] It will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein that various modifications and variations can be made in the endoscopic retrieval device formed of precursor alloy cable of the present invention. Therefore, the invention in its broader aspects is not limited to the specific details and illustrative examples shown and described in the specification. It is intended that departures may be made from such details without departing from the true spirit or scope of the general inventive concept as defined by the following claims and their equivalents.
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A medical retrieval device for retrieving foreign objects from a patient and the method of constructing the device are disclosed. The device incorporates a wire cable composed of a precursor alloy to a superelastic material to improve durability of the device. Because precursor alloys exhibit a linear stress-strain relationship and a yield point associated with a relatively high stress level, the device transfers greater stresses before experiencing deformation. Thus, greater crushing forces can be achieved using a device of this type. These crushing forces may be needed when the foreign object is too large to remove intact. This property also facilitates the device in dilating ducts to retrieve foreign objects. Using the precursor alloy additionally eliminates the need for heat treatment of the cables used in constructing the device. A retrieval device made of precursor alloy cable also is less susceptible to permanent deformation and unwinding during use.
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BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to the field of computer user interface technology. More specifically, the present invention is related to a system and method for the recognition of reading, skimming, and scanning from eye-gaze patterns.
The following definitions may assist in the understanding of the terminology used through the specification:
heterogeneous content—objects (like icons, windows, menus, etc.) encountered in electronic displays (e.g., monitors). reading—a method of systematically and methodically examining and grasping the meaning of textual content. skimming—a method of rapidly moving the eyes over textual content with the purpose of getting only the main ideas and a general overview of the content. scanning—a method of rapidly covering a great breadth of the display in order to locate specific heterogeneous content. tokenization—the process of classifying a range of phenomena (i.e. eye movements) into discrete categories. quantization—integration (usually averaging) of a sequential group of measurements where the measurements in each group do not overlap. The measurements may be over time or space. database—any stored collection of information located on the local computer, a local area network (LAN) or and wide area network (WAN) including the world wide web (WWW) (note: any use of this term refers to the use of the term as defined in this way.)
2. Discussion of Prior Art
Computers are a widely used resource in today's society. In most systems, a user manipulates a keyboard or a mouse to communicate with a computer. Modern systems include a graphical user interface (GUI) which communicates with the user by displaying various heterogenous content. In the context of this patent application, heterogeneous content includes objects normally encountered on computer monitors. For example, as illustrated in FIG. 1 , heterogeneous content 100 includes (but is not restricted to) any of, or a combination of: text 102 , images 104 , hyperlinks 106 , windows 108 , icons 110 , or menus 112 . When users view a computer monitor with hetergeneous content displayed on its screen, they utilize an input device, such as a mouse or a keyboard, to manipulate one (or a combination of) heterogenous content items based on their interests. FIG. 2 illustrates a prior art system which comprises monitor 200 , computer CPU unit 202 , mouse 204 , and keyboard 206 . Users view on the computer monitor 200 various hetergeneous content items (like A, B, and C) and, based on their interest, they interact with one or more or a combination of heterogenous content items via mouse 204 or keyboard 206 . This step is very “user driven” since the system does not have a means for dynamically tracking user interests (whether they are interested in A, B, or C) regarding the displayed heterogenous content and hence the computer wants for the user to respond via input device before proceeding with any action.
Thus, there is a need for a system that can dynamically and accurately determine what heterogenous content a user is interested in and the relative level of interest. One way of determining this relative interest level is by detecting what area of the display the user holds eye movement to a minimum ( e.g., maintains a gaze). Yet another related way involves determining user interests by detecting (from eye-movement patterns or eye-gaze patterns) which part of the heterogenous display screen was read by the user.
Detecting when a user is reading rather than merely scanning or skimming from eye-gaze patterns is a difficult problem, as low-level eye movements are almost completely automatic (i.e., involuntary). Thus, low-level eye movements do-not follow the assumed pattern of right->right->right during reading but instead follow much more complex patterns.
FIG. 3 illustrates some of the common eye movements observed during, reading. Common eye movement behaviors observed in reading 300 include forward saccades (or jumps) 302 of various length (eye-movements to the right), micro-saccades (small movements in various directions) 304 , fixations of various duration 306 , regressions (eye-movements to the left) 308 , jitters (shaky movements) 310 , and nystagmus (a rapid, involuntary, oscillatory motion of the eyeball) 312 . As illustrated by FIG. 4 , these behaviors in turn depend on several factors 400 , some of which include (but are not restricted to): text difficulty 402 , word length 404 , word frequency 406 , font size 408 , font color 410 , distortion 412 , user distance to display 414 , and individual differences 416 . Individual differences that affect eye-movements further include, but are not limited to, reading speed 418 , intelligence 420 , age 422 , and language skills 424 . For example, as the text becomes more difficult to comprehend, fixation duration increases (as described by Just & Carpenter in their paper entitled, A theory of reading: From are fixations to comprehension , Psychological Review, 1980) and the number of regressions increases (as described by Rayner & Frazier in their paper entitled, Parsing temporarily ambigeous complements . Quarterly Journal of Experimental Psychology, 1987.) Given the complexity of eye-gaze patterns and the detailed information about the text and the individual required to predict these patterns, there have been no attempts to build a system to recognize until now.
Recent work in intelligent user interfaces has focused on making computers similar to an assistant or butler in supposing that the computer should be attentive to what the user is doing and should keep track of user interests and needs. Because the Microsoft Windows® operating system and other windows-based operating systems are ubiquitous and visually intensive, researchers have identified eye-gaze as a valuable way to determine user interest when interacting with most computer terminals. An effort to capitalize on eye-gaze as a measure of user interest was made in U.S. Pat. No. 5,886,683, which describes a method and apparatus for providing relevant information based on eye-gaze. In this case, interest in some display object (icon, image, or block of text) was determined based on a fixation threshold. Simply put, if the user looks at an object on the screen long enough, the system infers that the user is interested in that object. This same rule also applies to blocks of text. But, there is a need to determine different levels of user interest based on the type of user behavior, such as reading (high interest), skimming (medium), or scanning (low interest) as well as capturing the exact words on the screen that are involved.
Other researchers have been concerned more specifically with making sense out of complex, low level eye movement data. As noted, the eye is constantly moving. Even when one seems to be looking steadily at some object, the eye still makes micro-saccades (small movements), jitters (shaky movements), and nystagmus (compensatory movements to head motion). To provide eye movement data that is closer to what users experience, researchers have attempted to break down or filter complex raw eye movement data into a set of tokens. Work on fixation recognition that has formed the core of this research area was originally proposed by Jacobs in his paper entitled, Eye movement - based human - computer interaction techniques: Toward non - command interfaces , Advances in Human-Computer Interaction, 1990; and later in his paper entitled, What you look at is what you get: Eye movement - based interaction techniques , Proceedings ACM CHI'90 Human Factors in Computer Systems, 1990. The term “fixation” refers to an area of relatively stable gaze that lasts between 30 and 800 milliseconds. Although people are not aware of micro-saccades, they do report areas of fixation. Thus, fixation recognition is an attempt to determine where a user intended to look. Jacob's fixation recognition algorithm works by taking a 100 millisecond set of data (6 data points for this implementation) and if the points are all within 0.5 degrees of visual angle, then a fixation is said to be detected and located at the average point. The fixation continues as long as the gaze points stay within 1.0 degree of this average fixation point.
Obviously, the goal of Jacob's method is far different from that of the present invention's goal of recognizing reading. Let us assume that his method for fixation recognition is used by a simple algorithm for reading detection. For instance, suppose a series of say three fixations to the right, fixation->fixation->fixation, signal that reading is detected. Several problems occur when using this method for reading detection: (a) loss of information, (b) regressions, (c) eye movement on the Y axis, (d) resets to beginning of next line, (e) revisits to previous sentences.
Whatever the precise merits, features and advantages of the above cited references, none of them achieve or fulfills the purposes of the present invention.
SUMMARY OF THE INVENTION
The present invention is an implemented system and a general method for recognizing from eye-gaze patterns when the user is reading, skimming, or scanning on a display filled with heterogeneous content. Heterogeneous content includes objects normally encountered on computer monitors, such as text, images, hyperlinks, windows, icons, and menus. In one embodiment, the system uses information about what text the user is reading or skimming to infer user interest and uses this information to adapt to the user's needs. The adaptation process includes recording the text of interest in a user model and using the text to find related information from local machine databases, local area network databases, or wide area network databases such as the World Wide Web.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates examples of various heterogeneous content.
FIG. 2 illustrates prior art system showing a general computer setup.
FIG. 3 illustrates common eye movements observed in reading.
FIG. 4 illustrates some of the factors affecting eye movements.
FIG. 5 illustrates a method for recognizing, from eye-gaze patterns, when a user is reading, skimming, or scanning on a display filled with heterogenous content.
FIG. 6 illustrates the flowchart describing the functionality of the method in FIG. 5 .
FIG. 7 illustrates a system for recognizing, from eye-gaze patterns, when a user is reading, skimming, or scanning on a display filled with heterogenous content.
FIG. 8 illustrates the benefits of recognizing and tracking user reading and skimming.
FIG. 9 illustrates a method for utilizing user interest information to adapt to a user's needs.
FIG. 10 illustrates the adaptation process of the method in FIG. 9 .
FIG. 11 illustrates the various databases that can be used in conjunction with the adaptation process described in FIG. 10 .
FIG. 12 illustrates the system for utilizing user interest information to adapt to a user's needs.
FIG. 13 illustrates a method of paying for Internet advertisements.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
While this invention is illustrated and described in a preferred embodiment, the invention may be produced in many different configurations, forms and materials. There is depicted in the drawings, and will herein be described in detail, a preferred embodiment of the invention, with the understanding that the present disclosure is to be considered as a exemplification of the principles of the invention and the associated functional specifications of the materials for its construction and is not intended to limit the invention to the embodiment illustrated. Those skilled in the art will envision many other possible variations within the scope of the present invention.
FIG. 5 illustrates a method 500 for recognizing, from eye-gaze patterns, when a user is reading, skimming, or scanning on a display filled with heterogeneous content. The method comprises three mechanisms: (1) coarse or quantized representation of eye-movements 502 , (2) pooled evidence based detection 504 , and (3) mode switching 506 . This is further elucidated, as in FIG. 6 , via a flowchart 600 describing the functionality of the above described method. First, the eye-movements in both x and y positions are quantized (and averaged) 602 over 100 ms intervals. This process removes some of the inaccuracy of prior art eye-tracking hardware and reduces the influence of micro-saccades. Second, evidence of reading is accumulated 604 until it crosses a threshold value 605 . The system may increment a reading-evidence variable by 1, for instance, when the eye moves to the right and de-incrementing by 1, for instance, when the eye moves to the left. If the evidence reaches a threshold 608 of, say, 3, then “reading”is detected 610 and the mode switched 612 from scanning to reading. If the threshold is not reached 606 , then the system continues to collect evidence of reading.
Pooled evidence acts to reduce the influence of eye movements back to previously read words (regressions or revisits) and movements above and below the current line of text. Mode switching allows the present invention to essentially interpret the same eye movements differently, based on changes in context. For example, large eye movements to the left and slightly up mean, within a scanning context, that the user is continuing to scan, but within a reading context this movement is more likely to mean that the user is re-reading text and will continue the reading process. Depending on the difficulty of the text, users may often revisit text they have already read several sentences back to clarify ambiguities in the sentence they are currently reading. If this movement were only allowed to have one meaning, say that the user is scanning, then the tracking of reading would end prematurely on every revisit. If this movement were to only mean that the user is reading, then this would increase the number of false alarms or times the system detected reading when the user was not reading. Mode switching allows the present invention to account for this behavior in different contexts and as a result produce more robust reading detection and continuous, reliable read tracking.
FIG. 7 illustrates a system 700 for recognizing, from eye-gaze patterns, when a user is reading, skimming, or scanning on a display filled with heterogenous content. The system comprises: eye-movement-quantizer 702 which quantizes the eye-movement in both the x and y directions, reading-evidence-accumulator 704 which accumulates evidence of reading, and a threshold-rule-comparator 706 which compares the reading evidence against a threshold. If the reading evidence is above the threshold, reading-detector 708 detects reading and mode switcher 710 switches the mode from scanning to reading.
FIG. 8 illustrates the benefits of recognizing and tracking user reading and skimming 800 . Some of these benefits are discussed below:
A. One advantage is accurate feedback about the user's informational interests and needs 802 . It is possible, for example, to infer that a user read the text of a web page just because a program detected the page being loaded in the browser and that the page remained in the browser for, say, 10 minutes. But, the user might have loaded the web page and then, seeing it is of no interest, switched to another application. The present invention provides a direct, fine-grained, and application-independent method to determine what text the user has read and therefore providing a better basis on which to infer what concepts are of interest to the user. B. Another benefit is that more accurate feedback results in more accurate models of the user 804 . Thus, the present invention provides relevant and personal assistance for a variety of tasks commonly performed with PC's, such as searching for information on the Web, writing manuscripts, composing e-mail, or looking for a certain type of news (e.g., articles about baseball). For example, if a user model shows that user always reads articles on Astronomy, the system could direct news gathering agents to get articles that a user might be interested in, and to organize (prioritize) information that has already-been gathered. C. A more specific benefit is fine-grained information about a user's interest in Internet advertising 806 . Instead of merely measuring the amount of time the user looked at the advertisement (gaze-duration), the system records the text that the user read. Additionally, the present invention determines if the user carefully read the-text or just skimmed it. Thus, in addition to mere banner click points, the system, as a business method, awards a user different levels of gaze points or different cash amounts based on this fine-grained information (e.g. non-reading gaze=10 cents, skimming gaze=20 cents, and reading gaze=40 cents). Payment rates are determined by level of user interaction with advertisements. D. Another specific advantage is that by using gaze movements data, computer help systems are given more context information and therefore provide more accurate help 808 . Current context-sensitive help systems such as WinHelp from Microsoft Windows® require the user to press the “?” button and then select the problem topic. By analyzing reading data, however, the present invention may determine, for example, which text was re-read, perhaps suggesting confusion, and may determine which words were fixated on, perhaps because of a lack of familiarity. The system uses this data to decide what help topics to suggest and in what order. Additionally, the help text could be customized to avoid terms that the user is not familiar with. E. Finally, knowledge of whether the user is reading, skimming, or scanning is useful for creating adaptive peripheral displays 81 . When the user is reading, the display should be as “quiet” or as non-distracting as possible by reducing motion and eliminating auditory feedback. However, when the user is scanning, the display can be more assertive with its suggestions; for instance, becoming larger, flashing new information in red, or by giving audio effects for stock market action (e.g., a cheering and clapping sound when a stock hits a new high).
In one embodiment of the invention, as illustrated in FIG. 9 , the method 900 involves, first, recording the eye-gaze patterns of an user viewing heterogeneous content 902 . Second, determining (as described above) from the patterns whether the user is reading, skimming or scanning 904 . Last, the system uses information about what text the user is reading or skimming to infer user interest and uses this interest information to adapt to the user's needs via an adaptation process 906 . FIG. 10 further illustrates the adaptation process 1000 . First, the text that the user is interested in is recorded 1002 . Next, the system utilizes the recorded text to find relevant information from a database 1004 . Lastly, the retrieved relevant information is utilized to allow the system to adapt to the user's needs 1006 . FIG. 11 further illustrates that the database 1100 of step 1004 is one of the following: local machine database 1102 , local area network (LAN) database 1104 , wide area network (WAN) database 1106 such as the world wide web.
FIG. 12 illustrates a system 1200 to implement the above mentioned method. It comprises a gaze-pattern-recorder 1202 which records the gaze-pattern of a user, and a gaze-pattern-identifier 1204 which identifies whether a user is reading, skimming, or scanning. The system further includes a read-text-recorder 1206 which records the text that was read by the user. Lastly, the system includes an adapter 1210 , to adapt to user needs. In one embodiment, an information-retriever 1208 retrieves relevant information (related to read text) from a database and the system utilizes this information to adapt to user needs.
In another embodiment, as described by FIG. 13 , the present invention is used in a method 1300 of paying for Internet advertisements. First, the method determines the user activity 1302 by determining whether a user is reading, skimming, or scanning. Next, the method records the user's interests 1304 , for example, the system records text or words that the user is interested in. Furthermore, the method computes payments 1306 based on user activity and viewer interests and lastly, a payment is scheduled to the user 1308 .
As stated above, payments for ad interaction could be computed based on the
a) level of viewer interaction with the ad, (i.e. read, skimmed, or scanned), b) amount or proportion of text/content that the viewer interacts with (more content equals more payment), and c) the value of the text that the viewer interacts with.
Here, text value could be based on general guidelines like the company name and slogan are more important than other text. Alternatively text value could be defined by the advertiser so that, for example, words that convey key concepts are more important than the company name. Payments could also be calculated based on the three factors given above combined with viewer demographics and databases with additional historical information about viewer's behavior and attitudes. Viewer demographics such as age, gender, race, SES, education, religion, etc., can be obtained voluntarily from the viewer or by viewer identification combined with advertiser or third party databases.
Ad interaction or interest could also be a basis for determining ad effectiveness. Ad effectiveness is how well the advertisement conveys the message that the creators intended and whether or not the advertisement ultimately contributes to revenue. By knowing which text in the ad the viewer read or skimmed, the amount of text read, and the values of the text read, the effectiveness of the ad can be determined. For example, if 60% of people who looked at the ad read the words that convey the central concept of the ad, one may conclude that the ad is fairly effective. However, if 90% of people who looked at the ad did not read far enough down the text to get to the main point, then one may conclude that the ad is ineffective. This could be due to the fact that there is too much text or that the topmost text does not capture and hold the viewer's attention. Demographics information from advertiser or third party databases could also be used to determine if the ads are reaching the target audience.
Payments for ad interaction can be made to the viewer of the ad and/or to the advertiser and/or even to the creator of the ad. As pointed out above, some business models are based on paying or providing a service for viewers that have advertisements on their display. By providing payments or compensation based on ad interest, advertisers could ensure that viewers are actually receiving the message that the advertisers are trig to convey. Also by paying or compensating advertisers based on ad interest, advertisers can get credit for effectively placing ads so that the ad gets attention. On Web sites, advertisers can get credit for ads that attract attention but may not necessarily lead to click-throughs. Such may be the case if the Web user is searching for information and does not have time to go to the advertiser's site but quickly reads the ad for future reference. The ad agency can also be paid or otherwise compensated for how much interest the ad generates as an incentive or as part of a compensation package. Compensation for ad interest or interaction for any of the above parties is not limited to monetary transactions but could include goods, services (free Internet Service Provider; see NetZero.com), reward points (see MyPoints.com), promotional items, contest entries, gift certificates, bonds, stock, stock options.
The above mentioned user interest information and ad effectiveness could be transmitted to and stored in the advertiser's database so that statistics on ad viewing could be compiled and processed. Additional statistics could be calculated and published indicating which ad hosts do the best job of displaying ads and which ad agencies create ads that get attention or are effective.
An implementation of the present invention that was made fully functional on Jul. 18, 1999, is now described in more detail as the preferred embodiment. The system tracks the text a user is reading on a computer screen (in any application or window) and sends that text to interest tracking software called Suitor (as described by Maglio et al. in their paper entitled, SUITOR: An Attentive Information System , The International Conference on Intelligent User Interfaces, 1999), which then acts on this text by (a) obtaining web pages that are related to keywords in the text and (b) adding the text to a user model. The method used by this system to detect reading rather than scanning includes three processes, (a) quantizing the eye movement data, (b) pooling eye movement evidence and applying a threshold, and (c) mode switching. The term scanning is used here to include both exploratory and searching eye movements. Exploratory eye movements are meant to inspect the objects on the screen whereas searching eye movements are meant to find a specific object or class of objects on the screen.
A preferred embodiment of the present invention includes a system which first quantizes raw data sent from the eye tracking hardware by averaging every 3 data points. This raw data is provided by the eye tracker at a rate of 30 points (X and Y positions) per second, but after averaging is reduced to 10 data points per second or one data point every 100 milliseconds. The system is initially in scanning mode, which requires a set of events to occur to switch into reading mode. The events that are tracked include the specific eye movements shown in Table 1. For example, if the eye moves a short distance left then the event is a “regression saccade” but if the eye moves a long distance left then the event is a “scan jump”.
The quantized, tokenized stream of eye-movement data is then pooled to determine whether the user is reading. The pooled evidence for reading is calculated by taking the accumulated value of the pooled data and adding the points associated with the current event for both the X and Y axes. Thus, if a “read forward” event occurs for the X axis and a “skim jump” occurs for the Y axis then (10+−5)=5 points would be added to the pool. Note that it is possible to have no event occur for the X and/or Y axis if the eye does not move. Every non-event is given 0 points. For this implementation, the pooled evidence that a user is reading must cross a threshold of 30 points to switch into reading mode.
By using pooled evidence, the system does not have to look for a specific pattern of events but allows for a wide range of patterns to signal reading. Thus, reading recognition is tolerant to noise, maintains a high hit rate and low false alarm rate. For example, the events “read forward”, “skim forward”, “skim jump”, “read forward”, and “read forward” (10+5+−5+10+10=30 points) are sufficient to trigger reading detection. However, these five events may be ordered in different ways—there are exactly 20 possible permutations. Rather than looking for each of these 20 possible sets of events, pooled evidence allows the system to accumulate mounting evidence despite noise. Thus, increasing noise only delays reading detection but does not block it altogether. Ideally, the quickest reading could be detected is if the highly unlikely pattern, read forward->read forward->read forward, occurs. Because the system samples in 100 millisecond increments, 3×100=300 milliseconds or about one-third of a second is the fastest possible reading detection time.
Once the threshold is passed, reading is detected and mode changes from “scanning” to “reading” mode. In reading mode, the rules for changing back to scanning mode are different. The system records every word read in reading mode until a “scan jump” event is detected. A single “scan jump” event will send the-system back into scanning mode. This method of mode switching allows for fairly quick changes in modes while still maintaining reliable read tracking. Reliable read tracking is important because readers will often show a wide range of behaviors while reading, including long pauses on ambiguous words, large regressions to text that may help to disambiguate the current sentence, and moderate forward jumps in anticipation of upcoming text.
Alternative embodiments include:
A. Skimming detection. The method for detecting skimming includes recording, in reading mode only, the distance of each eye-movement. If the distance is less than some threshold, then the words that the eye moved across are classified as read; but if the distance is greater than some threshold, then the words are classified as skimmed. In other words, if the eye moves quickly over some words then those words were skimmed. B. Adaptive parameters. The method will include parameters that adapt to individual reading speeds and abilities by adjusting parameters that are used to determine the actual vales of the distances: short, medium, and long in Table 1. If, for example, the system determines that the user is a slow and careful reader, then all the distances (for the X axis) should be decreased to optimize performance. If, on the other hand, the system determines that the user's reading ability is poor, then mote regressions will occur and the mode switching threshold should be decreased (to be more sensitive).
TABLE 1
Tokenization of Eye Movements and Evidence for Reading
Distance, direction, axis
Token
Points (Evidence for Reading)
short right X:
read forward
10
medium right X:
skim forward
5
long right X:
scan jump
resets the evidence counter
short left (back) X:
regression
−10
saccade
medium left X:
skim jump
−5
long left X:
scan jump
resets the evidence counter
short up Y
skim jump
−5
medium up Y
scan jump
resets the evidence counter
long up Y
scan jump
resets the evidence counter
short down Y
anticipatory
0
saccade
medium down Y
skim jump
−5
long down
scan jump
resets the evidence counter
long, medium left X
reset jump
5
and short, down Y
Note: Positive point values indicate evidence supporting reading and negative numbers indicate evidence against reading.
C. Context information. The method will also include context information to constrain reading detection and improve accuracy and reliability. Useful context includes, (a) the location of text on the screen, (b) the size of the font, (c) the content of the text on the screen, (d) whether the user is scrolling, navigating, or pointing, and (e) the distance of the user from the screen. Mode switching between reading and scanning is improved by determining the size of the text on the retina of the eye, because this determines the size of eye movements in reading. In other words, the larger the text, the bigger the eye movements in reading. Determining the size of text on the retina requires knowing the size of the font and the distance of the user from the screen. For example, fine text is usually read more slowly. Finally, detecting the use of an input device may help to determine whether they are reading. For example, it is unlikely that the user is reading when navigating, pointing or scrolling (considering the jumpy scrolling behavior of a typical mouse).
The above enhancements for reading recognition systems and described functional elements may be implemented in various computing environments. For example, the present invention is implemented on a conventional IBM PC or equivalent, multi-nodal system (e.g. LAN) or networking system (e.g. Internet, WWW). All programming and data related thereto are stored in computer memory, static or dynamic, and may be retrieved by the user in any of: conventional computer storage, display (i.e., CRT) and/or hardcopy (i.e., printed) formats.
Conclusion
A system and method has been shown in the above embodiments for the effective implementation of recognizing from eye-gaze patterns when the user is reading, skimming, or scanning on a heterogenous content display. While various preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention, as defined in the appended claims. For example, the present invention should not be limited by software/program, computing environment, and specific computing hardware. In addition, specific chosen heterogeneous content objects or electronic source medium should not limit the scope of the invention.
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Accurately recognizing from eye-gaze patterns when a user is reading, skimming, or scanning on a display filled with heterogeneous content, and then supplying information tailored to meet individual needs. Heterogeneous content includes objects normally encountered on computer monitors, such as text, images, hyperlinks, windows, icons, and menus. Three distinct mechanisms are used: (1) coarse or quantized representation of eye-movements, (2) accumulation of pooled numerical evidence based detection, and (3) mode switching. Analysis of text the user is reading or skimming may infer user interest and adapt to the user's needs.
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TECHNICAL FIELD
The present invention relates to a heat cycle system including a heat engine that extracts power through a turbine and also relates to a heat cycle system comprising a combination of such a heat engine and a refrigerator. More particularly, the present invention relates to a technique for improving the thermal efficiency of a heat cycle system by combining together a heat engine and a refrigerator and transferring (heat crossing) the waste heat of turbine outlet steam to a working fluid at the turbine inlet side.
BACKGROUND ART
There have heretofore been many inventions using waste heat to improve the efficiency of a heat cycle system including a steam turbine. For example, JP-A-54-27640(Japanese Patent Public Disclosure) discloses an electric power generation system that recovers thermal energy of a high-temperature exhaust gas. The electric power generation system has a waste heat boiler installed at the upstream side of a high-temperature exhaust gas flow path and a fluid preheater at the downstream side thereof. Steam generated in the waste heat boiler is used to drive a steam turbine. A low-boiling point special fluid is preheated by the fluid preheater and further heated to evaporate by a fluid evaporator that utilizes the exhaust of the steam turbine. The evaporated special fluid drives a special fluid turbine. The output of the steam turbine and the output of the special fluid turbine are combined together to drive an electric generator to generate electric power. After being discharged from the special fluid turbine, the low-boiling point special fluid is condensed to liquid in a heat exchanger. The condensed liquid is pressurized by a pump and preheated by the heat exchanger before being recirculated to the fluid preheater.
Assuming that while a working substance is performing one cycle, i.e. undergoing successive changes and then returning to the previous state, it receives a quantity of heat Q h from a high heat source at a temperature T h and loses a quantity of heat Q b from a low heat source at a temperature T b to do work L (assumed to be a value expressed in terms of heat quantity) to the outside, the following relationship holds:
Q h =Q b +L (Eq. 1)
In heat engines, the work L is given to the outside. In refrigerators or heat pumps, the work L is given to a working fluid from the outside. In the case of heat engines, it is desirable that the quantity of heat Q h received from the high heat source should be minimum, and the work L given to the outside should be maximum. Accordingly, the following equation is referred to as thermal efficiency:
η= L/Q h (Eq. 2)
From the above equation, L may be rewritten as follows:
η=( Q h −Q b )/ Q h (Eq. 3)
The thermal efficiency η of a heat engine that performs a reversible Carnot cycle may be expressed by using thermodynamic temperatures T h ° K and T b ° K as follows:
η=( T h −T b )/ T h =1−( T b /T h ) (Eq. 4)
In general, an apparatus that transfers heat from a low-temperature object to a high-temperature object is called a “refrigerator”. The refrigerator is an apparatus that is generally used for the purpose of cooling objects. Meanwhile, an apparatus that transfers heat from a low-temperature object to a high-temperature object to heat the latter is referred to as a “heat pump”. The name “heat pump” may be regarded as an alias for the refrigerator when the usage is changed. The heat pump is used, for example, for a heating operation of an air conditioner for heating and cooling. The relationship between the quantity of heat Q b absorbed from a low-temperature object, the quantity of heat Q h given to a high-temperature object, and the work L (value expressed in terms of heat quantity) done from the outside to operate the heat pump is expressed as follows:
Q h =Q b +L (Eq. 5)
It can be said that, for the same work done, the larger the quantity of heat Q h given, the higher the cost efficiency of the heat pump. Accordingly, the following equation is referred to as the coefficient of performance of the heat pump:
ε= Q h /L (Eq. 6)
From the above Eq. 5, L is:
L=Q h −Q b (Eq. 7)
Hence, the performance coefficient ε is expressed as follows:
ε= Q h /( Q h −Q b ) (Eq. 8)
Assuming that the absolute temperature of the low heat source is T b ° 0 K and the absolute temperature of the high heat source is T h ° K, a heat pump that performs a reversible Carnot cycle exhibits the largest coefficient of performance among heat pumps operating between the two heat sources. The performance coefficient ε of the heat pump is:
ε= T b /( T h −T b ) (Eq. 9)
The reversible Carnot cycle consists of two isothermal changes and two adiabatic changes and exhibits the maximum thermal efficiency among all cycles operating between the same high and low heat sources.
FIG. 1 is an arrangement plan showing constituent elements of a conventional refrigerator J. Refrigerant gas Fg raised in pressure by a compressor C gives heat Q h to a fluid Z 1 in a heat exchanger (condenser) 7 , thereby being condensed. Thereafter, the refrigerant is expanded through an expansion valve V. Consequently, the refrigerant lowers in temperature and, at the same time, absorbs heat Q b from a fluid Z 2 in a heat exchanger 8 to cool the fluid Z 2 . Thereafter, the refrigerant is returned to the compressor C and then recirculated. Let us discuss the thermal calculation of a refrigerator arranged as shown in FIG. 1 and adapted to use ammonia as a refrigerant. For the sake of simplicity, let us assume that there is no mechanical loss. The temperature of the refrigerant is 110° C. (T 3 ) at the outlet of the compressor C, 38° C. (T 2 ) at the outlet of the condenser 7 , and −10° C. (T 1 ) at the outlet of the evaporator V. Therefore, the performance coefficient (theoretically maximum performance coefficient) ε of the refrigerator on the reversible Carnot cycle is:
ɛ
=
T
1
/
(
T
2
-
T
1
)
=
[
273.15
+
(
-
10
)
]
/
[
38
-
(
-
10
)
]
≈
5.4
(
Eq
.
10
)
In the refrigerator shown in FIG. 1 , if the input L (work) of the compressor C is assumed to be 1, because the performance coefficient of the refrigerator is +1, the performance coefficient ε h of the heat pump is:
ε h =5.4+1=6.4 (Eq. 11)
FIG. 2 is an arrangement plan showing basic constituent elements of a heat engine A including a steam turbine, i.e. a heat cycle system including a Rankine cycle. High-temperature and high-pressure steam Fg generated in a boiler B is supplied to a turbine S to rotate it, thereby generating power (work) W. The steam is cooled to form condensate Ee in a condenser Y 1 communicating with the exhaust opening of the turbine. The condensate Ee is raised in pressure by a pump P and then supplied to the boiler B. In the heat cycle system shown in FIG. 2 , when waste heat Q 2 from the condenser Y 1 is not utilized at all, work W (value expressed in terms of heat quantity) generated from the turbine S has no loss and is given by:
W=Q 1 −Q 2 (Eq. 12)
The thermal efficiency η s of the turbine S is:
η s =( Q 1 −Q 2 )/ Q 1 (Eq. 13)
In Eq. 13, Q 1 is the quantity of heat retained by the working fluid at the turbine inlet side, and Q 2 is the quantity of heat output from the working fluid at the turbine outlet side, which is equal to the quantity of waste heat discharged from the condenser Y 1 .
The thermal efficiency η 0 of the heat cycle system shown in FIG. 2 , i.e. the ratio η 0 of work W generated from the turbine S to the quantity of heat (retained heat quantity) Q 1 input to the working fluid in the heat cycle system, is given by:
η 0 =W/Q 1 (Eq. 14)
If W in Eq. 14 is replaced by W=Q 1 −Q 2 of Eq. 12, we have:
η 0 =( Q 1 −Q 2 )/ Q 1 (Eq. 16)
This is the same as the above-mentioned η s . Therefore, the following relationship holds:
η 0 =η s (Eq. 17)
In the heat cycle system of FIG. 2 , if a part or whole Q 3 of the waste heat Q 2 from the condenser Y 1 is transferred to the condensate at the boiler inlet by a feedwater preheater Y 2 , i.e.
0≦Q 3 ≦Q 2 (Eq. 18)
and, at the same time, the quantity of heat input to the boiler is reduced by the same amount as the quantity of heat transferred from the condenser Y 1 , then the boiler input heat quantity is Q 1 −Q 3 . The quantity of heat retained by steam Fg at the inlet of the turbine S is given by:
Boiler input heat quantity ( Q 1 −Q 3 )+(heat quantity Q 3 transferred by Y 2 )= Q 1 (Eq. 19)
The quantity of heat retained by steam Fg at the outlet of the turbine S can be regarded as being Q 2 . Therefore, power W (value expressed in terms of heat quantity) generated from the turbine S is:
W=Q 1 −Q 2 (Eq. 20)
Hence, the thermal efficiency η s of the turbine S is:
η s =( Q 1 −Q 2 )/ Q 1 (Eq. 21)
Thus, the thermal efficiency η s of the turbine S is the same as in the case where the waste heat Q 2 from the condenser Y 1 is not utilized.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a heat cycle system wherein the waste heat of steam turbine outlet steam is transferred (heat crossing) to a working fluid at the steam turbine inlet side, thereby allowing the thermal efficiency of the heat cycle system to increase even when the thermal efficiency of the turbine itself is small. It is also an object of the present invention to increase the thermal efficiency of a heat cycle system including a steam turbine and also a heat cycle system comprising a combination of a steam turbine and a refrigerator. More specifically, an object of the present invention is to increase the thermal efficiency of a heat cycle system by transferring (heat crossing) the waste heat of steam turbine outlet steam to a working fluid at the steam turbine inlet side. Another object of the present invention is to increase the thermal efficiency of a heat cycle system by transferring waste heat or heat in nature to a working fluid by using a heat pump. Still another object of the present invention is to minimize the quantity of externally dissipated heat from a condenser of a refrigerator and to extract a controlled heat quantity as power without effecting heat crossing.
A further object of the present invention is to convert low-temperature waste heat having low utility, e.g. low-temperature waste heat in a Rankine cycle, into a high-temperature thermal output by using a refrigerator. A still further object of the present invention is to provide a heat cycle system wherein the refrigeration output of a refrigerator is used as a low heat source of a condenser (cooler) installed at the turbine outlet in a Rankine cycle, and the refrigerator is operated as a heat pump, thereby allowing heat emitted from the condenser to be raised in temperature and supplied as a thermal output to the outside. A part of the thermal output supplied to the outside is usable as a heat source for heating in the Rankine cycle. In the present invention, the heat crossing ratio Q 3 /Q 1 is increased by using a refrigerating cycle, so that η=1 . . . (Eq. 27) is realized in η=η s /(1−Q 3 /Q 1 ) . . . (Eq. 32), or η is made as close to 1 as possible. In the present invention, the refrigerating cycle has a turbine installed upstream of a condenser in a conventional refrigerating cycle in which a refrigerant is compressed by a compressor. The condenser is equivalent to a condenser in a stream turbine cycle. Other objects of the present invention will be made apparent in the following description of the invention.
In the heat cycle system of FIG. 2 , if a part or whole Q 3 of the waste heat Q 2 from the condenser Y 1 is transferred to the condensate at the boiler inlet by the feedwater preheater Y 2 and, at the same time, the boiler input heat quantity is reduced by the same amount as the heat quantity Q 3 transferred from the condenser Y 1 , i.e. (Q 1 −Q 3 ), the thermal efficiency η of the heat cycle system shown in FIG. 2 , that is, the ratio of the work W generated from the turbine S, i.e. W=Q 1 −Q 2 . . . (Eq. 22), to the input heat quantity of the heat cycle system, i.e. (Q 1 −Q 3 ), is expressed as follows:
η= W /( Q 1 −Q 3 )=( Q 1 −Q 2 )/( Q 1 −Q 3 ) (Eq. 23)
In the heat cycle system of FIG. 2 , if the waste heat Q 2 from the condenser Y 1 is not utilized at all, i.e. Q 3 =0, the above Eq. 23 becomes as follows:
η=( Q 1 −Q 2 )/ Q 1 (Eq. 24)
In the case of 0≦Q 3 ≦Q 2 . . . (Eq. 18), we have:
η=( Q 1 −Q 2 )/( Q 1 −Q 3 ) (Eq. 25)
In the case of Eq. 25, the denominator is smaller than that in Eq. 24 by −Q 3 , and hence the value of η becomes correspondingly larger than in Eq. 24.
If the whole Q 2 of waste heat from the condenser is transferred to the condensate at the upstream or downstream side of the pump P, we have:
Q 2 =Q 3 (Eq. 26)
Hence, the thermal efficiency η of the heat cycle system is:
η=1 (Eq. 27)
In the heat cycle system of FIG. 2 , the thermal efficiency η thereof in the case of 0≦Q 3 ≦Q 2 . . . (Eq. 18) is, as stated above, given by:
η=( Q 1 −Q 2 )/( Q 1 −Q 3 ) (Eq. 28)
If the denominator and numerator of Eq. 28 are each divided by Q 1 , we have:
η=[( Q 1 −Q 2 )/ Q 1 ]/[( Q 1 −Q 3 )/ Q 1 ] (Eq. 29)
Eq. 29 may be modified as follows:
η=[( Q 1 −Q 2 )/ Q 1 ]/[1−( Q 3 /Q 1 )] (Eq. 30)
If η s =(Q 1 −Q 2 )/Q 1 . . . (Eq. 21) is inserted into Eq. 30, we have:
η=η s /(1 −Q 3 /Q 1 ) (Eq. 32)
In the present invention, even heat having low utility value, such as waste heat, is taken into the heat cycle system by using a heat pump, and a power output is taken out by a turbine in the heat cycle system. The heat cycle system according to the present invention uses heat crossing to extract power from the turbine at high efficiency. When the whole of waste heat Q 2 from the condenser Y 1 is utilized, the thermal efficiency η of the heat cycle system is η=1 according to Eq. 27.
As will be understood from the above Eq. 32, the thermal efficiency η of the heat cycle system is determined by the thermal efficiency η s of the turbine S and the heat quantity Q 3 transferred from the waste heat of the condenser Y 1 to the condensate at the upstream or downstream side of the pump P. As Q 3 increases to approach Q 1 , the denominator of Eq. 30, i.e. (1−Q 3 /Q 1 ), decreases. Consequently, η increases. It is difficult to increase the heat crossing ratio Q 3 /Q 1 in heat cycles other than the refrigerating cycle. The reason for this is that it is impossible to increase the temperature difference between a high heat source and a low heat source for heat transfer (heat crossing). Further, Eq. 27 cannot be realized in heat cycles other than the refrigerating cycle.
A heat cycle system according to a first feature of the present invention includes a compressor, a turbine, heat exchangers, and a pump. In the heat cycle system, a working gas (refrigerant gas) compressed in the compressor (C) drives the turbine (S) to deliver work (W 1 ). Thereafter, the working gas is cooled by passing through the heat dissipating side of the first heat exchanger ( 7 ) and then raised in pressure by the pump (P) to form high-pressure working liquid. The high-pressure working liquid drives a reaction water turbine (K) to deliver work (W 2 ). At the same time, the working liquid is expanded, and a part of it evaporates. The remaining liquid passes through the heat absorbing side of the first heat exchanger ( 7 ) and through the second heat exchanger ( 8 ), thereby being heated to evaporate. Thereafter, the working gas is introduced into the compressor (C) in a somewhat overheated state ( FIG. 3 ).
Preferably, the work (W 2 ) delivered from the reaction water turbine (K) and power (L 2 ) consumed by the pump (P) approximately cancel each other. In addition, a compressor driving motor (M 1 ), a turbogenerator (G 1 ), a pump driving motor (M 2 ), and a water turbine-driven generator (G 2 ) are electrically connected to each other ( FIGS. 3 and 5 ). The second heat exchanger ( 8 ) may be a condenser that transfers the waste heat of turbine exhaust steam in a Rankine cycle to the working gas ( FIG. 6 ). The second heat exchanger ( 8 ) may be a heat exchanger that transfers waste heat from a fuel cell to the working gas ( FIG. 14 ).
In the heat cycle system according to the first feature of the present invention, the reaction water turbine (K) may be simply an expansion valve (V) ( FIG. 4 ). In this case, the high-pressure working liquid raised in pressure by the pump (P) is expanded through the expansion valve (V). Consequently, a part of the working liquid evaporates to form working gas. The remaining liquid passes through the first heat exchanger ( 7 ) and through the second heat exchanger ( 8 ), thereby being heated to evaporate. Thereafter, the working gas is introduced into the compressor (C) in a somewhat overheated state ( FIG. 4 ). The heat cycles of the systems shown in FIGS. 3 and 4 are basic cycles in the present invention. The heat cycle shown in FIG. 4 is a simplified version of the heat cycle shown in FIG. 3 .
In the heat cycle system according to the first feature of the present invention, the thermal efficiency η of the heat cycle system is:
η
=
(
Q
1
-
Q
2
)
/
(
Q
1
-
Q
3
)
(
Eq
.
28
)
=
η
s
/
(
1
-
Q
3
/
Q
1
)
Q
3
=
(
1
to
0.1
)
Q
2
(
Eq
.
32
)
where:
η s is the thermal efficiency of the turbine; Q 1 is the quantity of input heat transmitted to the working fluid at the turbine inlet side; Q 2 is the quantity of heat output from the working fluid at the turbine outlet side; and Q 3 is the quantity of heat transferred (heat crossing) from the working fluid at the turbine outlet side to the working fluid at the turbine inlet side.
As Q 3 increases, the denominator of Eq. 28 or 32 decreases, and the thermal efficiency η of the heat cycle system increases.
A heat cycle system according to a second feature of the present invention includes a compressor, a turbine, heat exchangers, and a pump. In the heat cycle system, a working gas (refrigerant gas) compressed in the compressor (C) drives the turbine (S) to deliver work (W 1 ). Thereafter, the working gas is cooled by passing through the heat dissipating side of the first heat exchanger ( 7 ) and then raised in pressure by the pump (P) to form high-pressure working liquid (refrigerant liquid). The high-pressure working liquid drives a reaction water turbine (K) to deliver work (W 2 ). At the same time, the working liquid is expanded and evaporated through an evaporator (R) to form working gas. The working gas is introduced into the compressor (C) ( FIG. 7 ).
A heat cycle system according to a third feature of the present invention includes a boiler, a turbine, a heat exchanger, and a pump. In the heat cycle system, steam generated in the boiler (B) drives the turbine (S 2 ) to deliver work (W 3 ). Thereafter, the steam is cooled by passing through the heat dissipating side of the condenser (Y 1 ) and then raised in pressure by the pump (P 2 ) to form high-pressure working liquid. The high-pressure working liquid is heated by passing through the heat receiving side of the condenser (Y 1 ) before being returned to the boiler (B). Preferably, the steam that is cooled by passing through the heat dissipating side of the condenser (Y 1 ) is further cooled by an external cooling fluid (U) before being sucked into the pump (P 2 ). By doing so, a thermal output (Q 4 ) can be supplied to the outside ( FIG. 8 ). In this heat cycle system also, the following equation holds:
η=η s /(1 −Q 3 /Q 1 ) (Eq. 32)
A heat cycle system according to a fourth feature of the present invention comprises a combination of a heat engine including a boiler, a turbine, a condenser, and a pump, and a refrigerator including a compressor, a heat exchanger, and an expansion valve. In the heat cycle system, steam (Eg) generated in the boiler (B) drives the turbine (S 2 ). Thereafter, the steam is cooled in the condenser (Y 1 ) and raised in pressure by the pump (P 2 ) to form high-pressure condensate, which is then recirculated to the boiler (B). Refrigerant gas (Fg) compressed in the compressor (C) is cooled and liquefied at the heat dissipating side of the heat exchanger ( 7 ) to form refrigerant liquid (Fe). The refrigerant liquid (Fe) is expanded through the expansion valve (V) to form refrigerant gas (Fg) and then introduced into the condenser (Y 1 ), where the refrigerant gas (Fg) cools the steam (Eg) exhausted from the turbine. At the same time, the refrigerant gas (Fg) itself is heated and then returned to the compressor (C). Preferably, the high-pressure condensate is heated by passing through the heat receiving side of the heat exchanger ( 7 ) before being recirculated to the boiler (B). The heat receiving side of the heat exchanger ( 7 ) supplies a thermal output (U 2 ) to the outside ( FIG. 9 ).
According to a fifth feature of the present invention, the refrigerator in the heat cycle system comprising a combination of the heat engine and the refrigerator includes a turbine (S), a pump (P 1 ), and a reaction water turbine (K). Refrigerant gas compressed in the compressor (C) drives the turbine (S) to deliver work (W 1 ). Thereafter, the refrigerant gas is cooled by passing through the heat dissipating side of the heat exchanger ( 7 ) and then raised in pressured by the pump (P 1 ) to form high-pressure refrigerant liquid. The high-pressure refrigerant liquid drives the reaction water turbine (K) to deliver work (W 2 ). At the same time, the refrigerant liquid is expanded and evaporated to form refrigerant gas. The refrigerant gas is heated by passing through the heat absorbing side of the heat exchanger ( 7 ) and through the condenser (Y 1 ). Thereafter, the refrigerant gas is introduced into the compressor (C). The high-pressure condensate is heated in the condenser (Y 1 ) before being recirculated to the boiler (B) ( FIG. 10 ).
A heat cycle system according to a sixth feature of the present invention comprises a combination of a heat engine and a refrigerator including a compressor, a turbine, heat exchangers, a pump, and an expansion valve. In the heat cycle system, refrigerant gas (Fg) compressed in the compressor (C) drives the turbine (S) to deliver work (W 1 ). Thereafter, the refrigerant gas is cooled at the heat dissipating side of the heat exchanger ( 7 ) and then raised in pressure by the pump (P 1 ) to form high-pressure refrigerant liquid (Fe). The high-pressure refrigerant liquid drives the reaction water turbine (K) to deliver work (W 2 ). At the same time, the refrigerant liquid is expanded and evaporated to form refrigerant gas (Fg). The refrigerant gas is introduced into the heat exchanger ( 8 ), where it is heated by waste heat from the heat engine (D), and then returned to the compressor (C). Preferably, the compressor (C) is driven by either the output (W 3 ) from the heat engine (D) or a fuel cell ( FIGS. 12 and 13 ).
The heat cycle system ( FIGS. 6 and 9 ) according to the present invention that comprises a combination of a Rankine cycle and a refrigerator having a turbine does not require water for cooling that is indispensable when the Rankine cycle is operated singly, not in combination with a refrigerator. Capability of installing the Rankine cycle without the need of cooling water allows conditions of location for thermal electric power plants to be eased extremely and increases the possibility of siting thermal electric power plants in places that produce fuel or biomass fuel. In the case of electric power plants that use coal as fuel, in particular, the possibility of improving economic effect can be increased by generating electricity near a coal producing region and transmitting it to a place where electric power is consumed.
The present invention is capable of recovering power from the heat of condensation in a refrigerator and of minimizing the release of heat to the outside of the system, as shown in the heat cycle system of FIG. 3 . Therefore, the present invention has the advantageous effect of easing the “heat island” phenomenon, which has been deteriorating the environment of large cities in recent years.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an arrangement plan showing constituent elements of a conventional refrigerator.
FIG. 2 is an arrangement plan showing basic constituent elements of a conventional heat engine including a turbine, i.e. a heat cycle system that performs a Rankine cycle.
FIG. 3 is an arrangement plan of a heat cycle system according to a first embodiment of the present invention.
FIG. 4 is an explanatory view showing an example of temperature and pressure in a heat cycle system according to a modification of the first embodiment of the present invention.
FIG. 5 is an explanatory view showing an example of heat quantity in the heat cycle system according to the first embodiment of the present invention.
FIG. 6 is an arrangement plan of a heat cycle system according to a second embodiment of the present invention.
FIG. 7 is an arrangement plan of a heat cycle system according to a third embodiment of the present invention.
FIG. 8 is an arrangement plan of a heat cycle system according to a fourth embodiment of the present invention.
FIG. 9 is an arrangement plan of a heat cycle system according to a fifth embodiment of the present invention.
FIG. 10 is an arrangement plan of a heat cycle system according to a sixth embodiment of the present invention.
FIG. 11 is an arrangement plan of a heat cycle system according to a modification of the sixth embodiment of the present invention.
FIG. 12 is an arrangement plan of a heat cycle system according to a seventh embodiment of the present invention.
FIG. 13 is an arrangement plan of a heat cycle system according to an eighth embodiment of the present invention.
FIG. 14 is an arrangement plan of a heat cycle system according to a ninth embodiment of the present invention.
EXPLANATION OF REFERENCE SYMBOLS
A, D: heat engine; B: boiler; C: compressor; ε: performance coefficient; η: thermal efficiency of heat cycle system; η s : thermal efficiency of turbine as used singly; Eg: steam; Ee: water (feedwater or condensate); Fg: refrigerant gas; Fe: refrigerant liquid; G 1 , G 2 : electric generator; J: refrigerator; K: water turbine; L 1 , L 2 : work (input); N: fuel cell; M 1 , M 2 : motor; P: pump; Q 1 , Q 2 , Q 3 , Q 4 : heat quantity; S, S 2 : turbine; V: expansion valve; W 1 , W 2 , W 3 : work (output); 7 , 8 : heat exchanger; Y 1 : condenser; Y 2 : feedwater preheater.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 is an arrangement plan of a heat cycle system according to a first embodiment of the present invention. The heat cycle system has an arrangement in which a turbine S and so forth are inserted into a refrigerator including a compressor C and a condenser. A working fluid (refrigerant gas) compressed in the compressor C drives the turbine S to deliver work W 1 . Thereafter, the working fluid is cooled and liquefied in a heat exchanger 7 (at the heat dissipating side thereof). A pump P connected to the outlet of the heat exchanger 7 sucks in the working liquid and lowers the back pressure of the turbine S, thereby increasing the turbine output W 1 and raising the pressure of the working liquid. The working liquid raised in pressure drives a reaction water turbine K to deliver work W 2 . At the same time, the working liquid is expanded through a nozzle of the reaction water turbine K that operates as an expansion valve. Thus, the working liquid evaporates to form working gas (refrigerant gas). The working gas is heated in the heat exchanger 7 (at the heat absorbing side thereof) and further heated in a heat exchanger 8 before being introduced into the compressor C.
In the heat cycle system of FIG. 3 , the heat exchanger 7 releases heat from the exhaust of the turbine S to heat the working gas at the outlet of the reaction water turbine K. In the heat exchanger 7 , the exhaust from the turbine S is cooled and condensed to liquid. The heat exchanger 7 in FIG. 3 increases the temperature difference between the working fluid at the inlet of the turbine S and the working fluid at the outlet thereof by cooling the exhaust from the turbine S, thereby increasing the turbine output. Waste heat Q 1 from the turbine exhaust is transferred (heat crossing) to the working fluid at the downstream side of the reaction water turbine K. The pressure of the working fluid is raised by the pump P because the working fluid pressure is excessively lowered by increasing the cooling capacity of the heat exchanger 7 . The working liquid raised in pressure is supplied to the reaction water turbine K where the potential energy of the working fluid is recovered. It is herein assumed that the potential energy is small relative to the whole, and the work consumed by the pump P and the output of the reaction water turbine K cancel each other.
In the heat cycle system of FIG. 3 , Q 3 is the quantity of transferred heat in the heat exchanger 7 , and Q 4 is the quantity of heat absorbed from the outside in the heat exchanger 8 . The output of the heat cycle system (the output of the turbine S) is given by:
(L 1 +Q 4 ) (Eq. 33)
The heat quantity Q 3 is the quantity of heat transferred from the working fluid at the outlet side of the turbine S to the working fluid at the inlet side of the compressor C to effect heat crossing.
FIG. 4 is an explanatory view showing a heat cycle system according to a modification of the first embodiment of the present invention in which an expansion valve V is used in place of the reaction water turbine K. FIG. 4 also shows an example of temperature and pressure in the heat cycle system. The exhaust from a turbine S is cooled to 0° C. (T 4 ) by refrigerant vapor at −10° C. (T 2 ) in a condenser (heat exchanger) 7 . Thereafter, the pressure of the refrigerant is raised from 4.39 kgf/cm 2 abs to 15.04 kgf/cm 2 abs by a pump p and thus liquefied. T 4 is the temperature of the refrigerant at the outlet of the condenser 7 in FIG. 4 . The refrigerant raised in pressure by the pump P is expanded and evaporated through the expansion valve V, and receives heat of Q 1 in the heat exchanger 7 to reach a temperature of −10° C. (T 2 ). The turbine inlet temperature is 110° C. (T 3 ), and the condenser refrigerant temperature is 0° C. (T 4 ). Therefore, the turbine efficiency η s on the Carnot cycle is:
η
s
=
(
T
3
-
T
4
)
/
T
3
=
(
110
-
0
)
/
(
273.15
+
110
)
≈
0.28
(
Eq
.
34
)
FIG. 5 is an explanatory view showing an example of heat quantity in the heat cycle system according to the first embodiment of the present invention. FIG. 5 illustrates the turbine output W 1 when the input L 1 of the compressor C is thrown into the system in the amount of one unit (L 1 =1), together with the heat crossing quantity Q 3 at the outlet of the heat exchanger 7 , and the heat quantity Q 4 taken into the heat exchanger 8 from the outside. The performance coefficient ε h of the heat pump is the refrigerator performance coefficient plus 1, i.e.
ε h =5.4+1=6.4 (Eq. 35)
The output W 1 of the turbine S is given by:
W 1 =ε h ×η s =6.4×0.28≈1.7 (Eq. 36)
The heat crossing quantity Q 3 at the outlet of the heat exchanger 7 is:
Q 3 =6.4−1.7=4.7 (Eq. 37)
The heat quantity Q 4 absorbed from the outside in the heat exchanger 8 is:
Q 4 =refrigerator performance coefficient− Q 3 (Eq. 38)
Therefore, the heat quantity Q 4 is:
Q 4 =5.4−4.7=0.7 (Eq. 39)
FIG. 6 is an arrangement plan of a heat cycle system according to a second embodiment of the present invention. The heat cycle system shown in FIG. 6 is similar in arrangement to the heat cycle system according to the first embodiment ( FIG. 3 ) of the present invention except that the heat cycle system according to the second embodiment uses waste heat in a Rankine cycle A, i.e. waste heat from a condenser Y 1 of a steam turbine S 2 , as a heat source for the system. In the heat cycle system shown in FIG. 6 , the quantity of heat given to steam from a boiler B is 10,000 kW, and the output W 3 of the turbine S 2 is 3,000 kW (thermal efficiency: 0.3). Waste heat (condenser waste heat) from the turbine S 2 is 7,000 kW. The quantity of heat transferred from the steam Eg to the refrigerant Fg in the condenser Y 1 is 7,000 kW.
The quantity of heat coming into and out of each element of the system shown in FIG. 6 is obtained by a proportional calculation in which the quantity of heat absorbed from the outside in the condenser Y 1 in the heat cycle system of FIG. 5 , i.e. 0.7, is assumed to be 7,000 kW, that is, one unit in FIG. 5 is assumed to be 10,000 kW. The input L of the compressor C is L=10,000 kW, and the work W 1 of the turbine S is W 1 =17,000 kW. The heat crossing quantity Q 3 in the heat exchanger 7 is Q 3 =47,000 kW. The power L 2 consumed by the pump P 1 is 45 kW, and the power W 2 generated by the reaction water turbine K is 45 kW. The power of 45 kW is small relative to the input of 10,000 kW and therefore omissible without a problem.
FIG. 7 is an arrangement plan of a heat cycle system according to a third embodiment of the present invention. The heat cycle system shown in FIG. 7 is similar in arrangement to the heat cycle system according to the first embodiment ( FIG. 3 ) of the present invention except that the heat cycle system according to the third embodiment has a structure in which the heat absorbing side of the heat exchanger (condenser) 7 is an external thermal output (external cooling source) Z 1 , and there is no heat crossing between the exhaust of the turbine S and the intake of the compressor C. The heat cycle system of FIG. 7 has a turbine S installed at the upstream side of the condenser 7 of the refrigerator to obtain an output (power or work) W 1 . In the heat cycle system of FIG. 7 , the thermal efficiency η s of the turbine S on the Carnot cycle is:
η s =(110−38)/273.15+110≈0.18 (Eq. 40)
The refrigerator performance coefficient ε on the reversible Carnot cycle is:
ε=[273.15+(−10)]/[38−(−10)]≈5.4 (Eq. 41)
The output (power or work) W 1 of the turbine S is:
W 1 =(ε+1)×η s ≈1.1 (Eq. 42)
Assuming that the ratio of the pumping power L 2 of the pump P to the power L 1 of the compressor is 0.4%, the pumping power L 2 of the pump P is:
L 2 =0.004 (Eq. 43)
The work W 1 obtained from the turbine S is:
W 1 ≈1.1 (Eq. 44)
Because the work W 1 obtained from the turbine S is much larger than the pumping power L 2 of the pump P, the advantage of extracting power from the turbine S is great in comparison to the system configuration in which heat is merely dissipated from the heat exchanger 7 .
FIG. 8 is an arrangement plan of a heat cycle system according to a fourth embodiment of the present invention. The heat cycle system shown in FIG. 8 has a heat engine A including a boiler B, a turbine S 2 , and a condenser Y 1 . In the condenser Y 1 , waste heat is transferred to feedwater at the boiler inlet. That is, heat crossing is effected in the heat cycle system. The heat cycle system of FIG. 8 further has an arrangement for supplying a thermal output U from the condenser Y 1 to the outside.
FIG. 9 is an arrangement plan of a heat cycle system according to a fifth embodiment of the present invention. The heat cycle system shown in FIG. 9 has a heat pump (refrigerator J) combined with the heat engine A to effect increased heat crossing in the heat engine A. In the heat cycle system of FIG. 9 , steam Eg generated in the boiler B drives the turbine S 2 . Thereafter, the steam Eg is cooled in the condenser Y 1 and raised in pressure by a pump P 2 to form condensate Ee. The condensate Ee is heated to a temperature, for example, of 80° C. in the heat exchanger 7 (at the heat receiving side thereof) of the refrigerator J before being recirculated to the boiler B. Refrigerant vapor Fg compressed in the compressor C is cooled and liquefied in the heat exchanger 7 (at the heat dissipating side thereof) to form refrigerant liquid Fe. At the same time, the refrigerant generates a thermal output (hot water supply) U 2 at 80° C., for example, and heats the condensate Ee in the heat engine A to 80° C. The refrigerant liquid Fe is expanded through an expansion valve V to form refrigerant vapor Fg at 4° C., for example, which is then introduced into the heat exchanger Y 1 to cool the steam Eg. Accordingly, increased heat crossing is effected between the exhaust steam Eg and the condensate Ee in the heat engine.
In the heat cycle system of FIG. 9 , one example of an operation of the heat engine carried out in a state where the heat pump J is at rest (i.e. heat exchange is effected directly between the exhaust steam Eg and the condensate Ee in the heat engine) is as follows. The steam temperature (turbine inlet) is 400° C., and the condensate temperature (turbine outlet) is 60° C. The thermal efficiency η on the Carnot cycle is:
η=(400−60)/(400+273.15)≈0.505 (Eq. 45)
On the other hand, when the heat pump J is operated as shown in FIG. 9 with the steam temperature set at 400° C., the condensate temperature (turbine outlet) is 10° C. The thermal efficiency η on the Carnot cycle is:
η≈0.579 (Eq. 46)
This shows that operating the heat pump in the heat cycle system of FIG. 9 causes the temperature difference to increase from 340° C. to 390° C. and allows the thermal efficiency of the turbine main unit to increase by:
0.579−0.505=0.074 (Eq. 47)
Next, let us discuss the heat crossing in the heat cycle system of FIG. 9 . When the heat pump J is at rest and no heat crossing is available, the condensate temperature (turbine outlet) and the feedwater temperature (boiler inlet) are both 10° C. In order to transform the condensate and the feedwater into steam at 400° C., 90 units of quantity of heat are required to heat the feedwater from 10° C. to 100° C., and 539 units of quantity of heat is required to transform the condensate at 100° C. into steam at 100° C. Further, 150 units of quantity of heat is required to heat the steam from 100° C. to 400° C. on the assumption that the specific heat of steam is 0.5. Accordingly, a total of 779 units of quantity of heat is required.
In a case where the heat pump is operated to effect heat crossing, the condensate temperature (turbine outlet) is 10° C., and the feedwater temperature at the boiler inlet is 70° C. Therefore, as compared to the boiler inlet feedwater temperature when no heat crossing is effected, i.e. 10° C., it is possible to save a quantity of heat which would otherwise be required to raise the feedwater temperature by 60° C., i.e. 60 units of quantity of heat. This is expressed as follows:
60/779=0.077 (Eq. 48)
Therefore, the reduction in the input heat quantity by heat crossing improves the thermal efficiency of the heat cycle system as follows.
From the above Eq. 32,
η=η s /(1 −Q 3 /Q 1 ) (Eq. 32), i.e.
η/η s =1/(1 −Q 3 /Q 1 ) (Eq. 49)
the thermal efficiency of the heat cycle system shown in FIG. 9 is:
1÷(1−0.077)=1.08 (Eq. 50)
Thus, the thermal efficiency improves by approximately 8%.
Next, let us discuss the increase of heat drop due to heat crossing in the heat cycle system of FIG. 9 . The thermal efficiency η s of the turbine when the heat pump is at rest and no heat crossing is available is:
η s =(400−10)/(400+273.15)=0.579 (Eq. 51)
Multiplying the thermal efficiency η s , i.e. 0.579, by the above-described increase rate of the thermal efficiency finds that the thermal efficiency of the heat cycle system is 0.625.
In the basic cycle ( FIG. 3 ) used in the present invention, the thermal efficiency can be improved by effecting heat crossing in the Rankine cycle even if the power consumed by the pump and the work generated from the reaction water turbine cancel each other or the power balance is somewhat positive. The improvement in the thermal efficiency can be attained without the need to increase the boiler capacity. For example, the steam temperature of 400° C., the condensate temperature (turbine outlet) of 60° C. and the boiler inlet feedwater temperature of 60° C. in the conventional system change to a steam temperature of 400° C., a condensate temperature (turbine outlet) of 10° C. and a boiler inlet feedwater temperature of 70° C., as stated above. Thus, the boiler inlet feedwater temperature only changes by 10° C. Accordingly, it is unnecessary to increase the boiler capacity.
FIG. 10 is an arrangement plan of a heat cycle system according to a sixth embodiment of the present invention. The heat cycle system shown in FIG. 10 comprises a combination of a heat engine A that per se performs heat crossing, and a heat pump (refrigerator J) including a turbine, wherein the turbine exhaust in the heat engine A is cooled by the refrigeration output of the refrigerator J. In the heat engine A of the heat cycle system shown in FIG. 10 , steam Eg generated from a boiler B drives a turbine S 2 . Thereafter, the steam Eg is cooled in a condenser Y 1 and raised in pressure by a pump P 2 to form condensate Ee. The condensate Ee is heated by the turbine exhaust steam in the condenser Y 1 before being recirculated to the boiler B. In the refrigerator J of the heat cycle system shown in FIG. 10 , refrigerant gas Fg raised in pressure by a compressor C drives a turbine S. Thereafter, the refrigerant gas Fg is cooled in a heat exchanger 7 (at the heat dissipating side thereof) and compressed and thus raised in pressure by a pump P 1 to form refrigerant liquid Fe.
The high-pressure refrigerant liquid Fe discharged from the pump P 1 drives a reaction water turbine K to deliver work W 2 . At the same time, the refrigerant liquid Fe is expanded and evaporated through a nozzle of the reaction water turbine K, which operates as an expansion valve, to form refrigerant gas Fg. The refrigerant gas Fg is heated in the heat exchanger 7 (at the heat absorbing side thereof) and further heated in the condenser Y 1 before being introduced into the compressor C. FIG. 11 is an arrangement plan of a heat cycle system according to a modification of the sixth embodiment of the present invention. In the heat cycle system shown in FIG. 11 , the turbine S 2 is mechanically connected to the compressor C so as to drive it, thereby eliminating the need of a motor for driving the compressor C. The rest of the arrangement of the heat cycle system is the same as that of the heat cycle system shown in FIG. 10 . Therefore, a repeated description thereof is omitted.
FIG. 12 is an arrangement plan of a heat cycle system according to a seventh embodiment of the present invention. The heat cycle system shown in FIG. 12 comprises a combination of a heat engine D using an Otto cycle, a Diesel cycle, a Sabathe cycle, or a Stirling cycle, and a refrigerator (heat pump) including a turbine. In the heat cycle system of FIG. 12 , an electric generator G 1 connected to the turbine, a compressor motor M, and an electric generator G 3 driven by the heat engine are electrically connected to each other. In the heat cycle system of FIG. 12 , refrigerant gas raised in pressured by a compressor C drives a turbine S. Thereafter, the refrigerant gas is cooled in a heat exchanger 7 (at the heat dissipating side thereof) and compressed and thus raised in pressure by a pump P 1 to form refrigerant liquid Fe.
The high-pressure refrigerant liquid Fe discharged from the pump P drives a reaction water turbine K to deliver work W 2 . At the same time, the refrigerant liquid Fe is expanded and evaporated through a nozzle of the reaction water turbine K, which operates as an expansion valve, to form refrigerant gas Fg. The refrigerant gas is heated in the heat exchanger 7 (at the heat absorbing side thereof) and further heated in a heat exchanger 8 by waste heat (cooling heat and exhaust gas heat) from the heat engine before being sucked into the compressor C. The waste heat from the heat engine is transferred to the refrigerant gas Fg in the heat exchanger 8 . The reaction water turbine K may be simply an expansion valve.
FIG. 13 is an arrangement plan of a heat cycle system according to an eighth embodiment of the present invention. The heat cycle system shown in FIG. 13 comprises a combination of a heat engine D using an Otto cycle, a Diesel cycle, a Sabathe cycle, or a Stirling cycle, and a refrigerator (heat pump) including a turbine, as in the case of the heat cycle system of FIG. 12 . In the heat cycle system of FIG. 13 , the compressor C is driven by the output of the heat engine. The arrangement of the rest of the heat cycle system is the same as that of the heat cycle system shown in FIG. 12 . In FIGS. 12 and 13 , the heat engine D uses any of an Otto cycle, a Diesel cycle, a Sabathe cycle, and a Stirling cycle.
FIG. 14 is an arrangement plan of a heat cycle system according to a ninth embodiment of the present invention. The heat cycle system shown in FIG. 14 comprises a combination of a fuel cell N and a refrigerator (heat pump) including a turbine. In the heat cycle system of FIG. 14 , refrigerant gas Fg raised in pressure by a compressor C drives a turbine S. Thereafter, the refrigerant gas Fg is cooled in a heat exchanger 7 (at the heat dissipating side thereof) and compressed and thus raised in pressure by a pump P to form refrigerant liquid Fe. The high-pressure refrigerant liquid Fe discharged from the pump P is expanded and evaporated through an expansion valve V to form refrigerant gas Fg. The refrigerant gas is heated in the heat exchanger 7 (at the heat absorbing side thereof) and further heated in a heat exchanger 8 by waste heat from the fuel cell N before being sucked into the compressor C. The waste heat from the fuel cell is transferred to the refrigerant gas Fg in the heat exchanger 8 . In the heat cycle system of FIG. 14 , an electric generator G connected to the turbine S, a compressor motor M, and the output of the fuel cell are electrically connected to each other.
|
A high-efficient heat cycle device formed by combining a heat engine with a refrigerating machine, wherein steam generated in a boiler is cooled by a condenser after driving turbine, built up by a pump, and circulated into the boiler in the form of high-pressure condensate. Refrigerant gas compressed by a compressor is passed through the radiating side of a heat exchanger for cooling after driving the turbine to output a work, and built up by a pump to form high-pressure refrigerant liquid. The high-pressure refrigerant liquid drives a reaction water-turbine to output a work and is expanded and vaporized to form refrigerant gas. The refrigerant gas is led into the compressor after being passed through the heat absorbing side of the heat exchanger and the condenser for heating.
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TECHNICAL FIELD
[0001] The present disclosure generally relates to hair care products, and more particularly to a hair volumizer and method of use.
BACKGROUND OF THE INVENTION
[0002] There have been many approaches to adding volume hair, such as hair spray and hair products, hair clips, clip-in hair extensions, and teasing brushes. Each of these existing approaches has problems. For example, hair spray and hair products leave hair stiff and chemically damaged. Hair clips remain visible when used, and are also difficult to properly place. Clip-in hair extensions have other problems: they are difficult to place and must exactly match the color of the existing natural hair, they are relatively expensive, and they have to be treated like existing hair by washing and styling them. Teasing brushes break and irreversibly damage hair. As a result, although there are existing methods and devices on the market that add volume to hair, they fail to provide an easy and effective way to maintain volume, while achieving a natural look, and without causing damage to existing hair.
SUMMARY OF THE INVENTION
[0003] A hair volumizer and method of use that provides an easy way to lift and add volume to existing hair, in a way that natural, and without breaking or chemically damaging the existing hair. In particular, the disclosed hair volumizer can be employed without assistance from others and results in hair having more and longer lasting volume without the need for hair sprays and products, hair extensions, teasing brushes or other materials or devices that can damage the existing hair or leave it looking and feeling unnatural.
[0004] Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0005] Aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, instead the emphasis is placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and in which:
[0006] FIGS. 1A-1C show before and after views of the consumer using the hair volumizer in accordance with an exemplary embodiment of the present disclosure;
[0007] FIGS. 2A and 2B are perspective views of the hair volumizer showing a plurality of clips in accordance with an exemplary embodiment of the present disclosure;
[0008] FIG. 3 is a side view of the hair volumizer showing tapered ends and clips in an open position, as well as the location of a flexible core;
[0009] FIG. 4 is a cross-section view of the hair volumizer;
[0010] FIGS. 5A and 5B are perspective views of the hair volumizer showing a plurality of clips in accordance with another exemplary embodiment of the present disclosure;
[0011] FIG. 6 is a side view of this exemplary embodiment of a hair volumizer, showing clips in an open position;
[0012] FIGS. 7A and 7B are perspective views of another exemplary embodiment of the hair volumizer in accordance with a shorter exemplary embodiment of the present disclosure;
[0013] FIG. 8 is a side view of the shorter embodiment of the hair volumizer, showing the clip in an open position; and
[0014] FIG. 9 is a diagram showing this shorter exemplary embodiment of a hair volumizer being placed in a different position on the user's head.
DETAILED DESCRIPTION OF THE INVENTION
[0015] In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals. The drawing figures might not be to scale and certain components can be shown in generalized or schematic form and identified by commercial designations in the interest of clarity and conciseness.
[0016] FIGS. 1A-1C show before and after views of a model using a hair volumizer 102 in accordance with an exemplary embodiment of the present disclosure. In FIG. 1 , the model's hair is shown in a natural, unaltered style. To use hair volumizer 102 , a lock of the hair is lifted and the hair volumizer 102 is clipped into place underneath the lifted lock of hair, as shown in FIG. 1B . The ends 108 of hair volumizer 102 are tapered and colored so as to blend in with the user's hair. The lifted lock of hair is then allowed to fall naturally over hair volumizer 102 , resulting in an increase in the hair volume as shown in FIG. 1C .
[0017] The use of hair volumizer 102 as described above results in a number of advantages over existing devices and techniques for increasing hair volume. One advantage is that hair volumizer 102 can be easily placed into position by the user, with little or no assistance from others. In addition, hair volumizer 102 also bends and shapes to fit the contours of the user's head. Thus, unlike most hair products on the market, the use of hair volumizer 102 does not require assistance by a hair-care professional.
[0018] Another advantage of the present disclosure is that hair volumizer 102 adds volume to the user's natural existing hair without the need for hair-stiffening compounds, such as hairspray or chemical products that can chemically damage the existing hair. Hair extensions are hard to match the consumer's natural existing hair color and texture. With hair volumizer 102 , the user's hair will thus look and feel completely natural, without taking too much time or the use of chemical products to apply.
[0019] Yet another advantage of the present disclosure is that hair volumizer 102 can be easily manipulated to conform to the user's head. As discussed in greater detail below, hair volumizer 102 includes a flexible core and foam polymer body that can be adapted to fit the contour of the user's head at the exact location where hair volumizer is installed. Unlike other clips or hair extensions, which are typically rigid and which may be difficult to place for that reason, hair volumizer 102 can bend easily, which facilitates both the placement of hair volumizer 102 and the appearance of hair volumizer 102 in use.
[0020] A further advantage of the present disclosure is that the use of hair volumizer 102 can reduce the need to repeatedly tease the user's natural hair. Teasing is a hair care technique that can be used to increase hair volume, but hair will typically fall back into place after being teased, requiring additional teasing. Such teasing can damage hair, and is therefore repeated teasing is not desirable. Hair volumizer 102 creates an effect similar to teasing without the accompanying hair damage and lasts until the user removes hair volumizer 102 .
[0021] FIGS. 2A and 2B are perspective views of hair volumizer 102 showing a plurality of clips 106 in accordance with an exemplary embodiment of the present disclosure. As shown in FIGS. 2A and 2B , the ends 108 of hair volumizer 102 are tapered at a suitable angle, so as to be less apparent, whereas the middle section of hair volumizer 102 is thicker, to provide additional gradual volume. The body of hair volumizer 102 is formed from a suitable foam material, such as a polymer foam, a natural foam material such as wool or cotton, or other suitable materials. In one exemplary embodiment, the outer surface of hair volumizer 102 can be wrapped in natural hair, such as from the person using hair volumizer 102 , so as to provide an exact match with the color of the user's hair, or using hair from other natural or artificial sources. The outer surface of hair volumizer 102 can also be treated to receive hair coloring dye, so as to allow a user to match the color of the outer surface of hair volumizer 102 to the user's hair when the user's hair is dyed.
[0022] Flexible core 104 of hair volumizer 102 can be formed from wire, flexible metal strips, or other suitable materials that can be easily adapted to follow the contours of the user's head, but which are sufficiently rigid not to change shape while being worn. Clips 106 are shown in an open position in FIG. 2A and in a closed position in FIG. 2B , and can be attached to flexible core 104 or separate from flexible core 104 . The use of a plurality of clips 106 and a flexible core 104 facilitates the use of hair volumizer 102 , which allows the user to attach hair volumizer 102 in a series of steps, so as to allow the user to change their position relative to a mirror to better see how each section of hair volumizer is being attached and to relocate individual sec needed. When closed, clips 106 securely hold each section of hair volumizer 102 in position to the user's existing hair without damaging the natural hair.
[0023] Referring now to FIG. 1B , it can be seen that the configuration of hair volumizer 102 when worn follows the contours of the user's head, and that hair volumizer 102 does not need to remain straight, as shown in FIGS. 2A and 2B . As such, hair volumizer 102 can be adapted both circumferentially and laterally, to provide volume in a desired location and also to allow the user's hair to be easily styled as desired. Thus, the user can easily adjust their hair style by adjusting and relocating hair volumizer 102 , as opposed to hair spray, which does not allow hair to be readily adjusted after it has been applied.
[0024] FIG. 3 is a side view of hair volumizer 102 showing tapered ends 108 and clips 106 in an open position, as well as the location of flexible core 104 (not explicitly shown). FIG. 4 is a cross-section view of hair volumizer 102 along cut line shown in FIG. 3 , which shows flexible core 104 contained within the foam material body of hair volumizer 102 , and clip 106 in an open position.
[0025] FIGS. 5A and 5B are perspective views of hair volumizer 102 showing a plurality of clips 106 in accordance with another exemplary embodiment of the present disclosure. As shown in FIGS. 5A and 5B , hair volumizer 102 can include a suitable number of clips to provide additional functionality for the placement and use of hair volumizer 102 . For example, clips 106 can be used to secure sections of the user's hair in position, in addition to providing volume by virtue of the foam material body of hair volumizer 102 . FIG. 6 is a side view of this exemplary embodiment of hair volumizer 102 , showing clips 106 in an open position.
[0026] FIGS. 7A and 7B are perspective views at another exemplary embodiment of hair volumizer 102 in accordance with an exemplary embodiment of the present disclosure. As shown in FIGS. 7A and 7B , hair volumizer 102 can be used in a shorter section, even properly operating with a single clip 106 or two or more clips, depending on the length of the embodiment of the hair volumizer. FIG. 7A displays the single clip embodiment, which is shown in an open configuration and in a closed configuration in FIG. 7B . FIG. 8 is a side view of the single clip embodiment of hair volumizer 102 , showing clip 106 in an open position.
[0027] FIG. 9 is a diagram showing this shorter exemplary Embodiment of hair volumizer 102 being placed in a different position on the user's head. As shown in FIG. 9 , the shorter embodiment can be used in smaller sections, which provides additional stylizing flexibility. Various suitable lengths of hair volumizer 102 can be provided to aid in a plethora of hairstyles.
[0028] Hair volumizer 102 can also be combined with hair extensions, where suitable, such as to provide additional volume in conjunction with the fullness that hair extensions offer. Although the hair extensions would still need to be matched to the hair color of the user's natural existing hair, the use of hair extensions in conjunction with hair volumizer 102 can increase the ease of placement of the hair extensions and give extra volume to the hair extensions which normally fall flat due to weight
[0029] It should be emphasized that the above-described embodiments are merely examples of possible implementations. Many variations and modifications may be made to the above-described embodiments without departing from the principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.
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An apparatus for hair care comprising an elongate foam body having tapered ends. A flexible core embedded within the foam body. Clips attached to the foam body, clips having an open position and a closed position. Wherein the foam body is configured to be placed underneath a user's existing natural hair and to be covered by the user's existing natural hair when secured in position by the plurality of clips. Wherein the flexible core is configured to be adapted to a contour of the user's head.
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CROSS-REFERENCE
[0001] This application is a section 371 of PCT/EP05/014 154, filed 31 Dec. 2005, published 24 Aug. 2006 as WO-2006-087031-A.
FIELD OF THE INVENTION
[0002] The invention relates to a heat exchanger for cooling a cooling medium, in particular in an electrical/electronic device.
BACKGROUND
[0003] In a closed cooling system filled with a coolant, temperature changes as well as permeation, for example through tube walls, result in a change in the volume of the coolant. Some compensation or equalization for this coolant volume change, that ensures that no, or only small, pressure changes occur in the system, must be found.
[0004] Such changes in volume can be buffered by means of a so-called equalizing vessel. This causes additional costs, however, and also increases the risk of cooling medium leaking out.
[0005] An important problem in the context of heat exchangers for electronic devices is that their exact operating orientation is not known, a priori. This is true not least for transportation to the customer, since such cooling systems are already filled with cooling medium at the manufacturer's premises, and the orientation they will assume during transport cannot be predicted. The same is true for utilization in vehicles of all kinds (aircraft, ships, land vehicles, vehicles in a weightless state). Operating reliability must therefore be guaranteed in all conceivable operating orientations. If liquid were to mix with gas in the cooling circuit, reliable operation of a circulating pump would then no longer be guaranteed, with the result that cooling performance might rapidly decrease. This would then very quickly cause the electronic component being cooled either to switch itself off, or to be destroyed by the increase in temperature.
SUMMARY OF THE INVENTION
[0006] It is therefore an object of the invention to make available a novel heat exchanger.
[0007] According to the invention, this object is achieved by forming a two-part equalizing vessel, incorporating a flexible membrane which dynamically adapts to changes in coolant volume, as part of a heat exchanger, one part being implemented as part of the inflow and one part being implemented as part of the outflow of the heat exchanger.
[0008] A compact and economical arrangement is thereby achieved. The risk that cooling medium may leak out and cause damage to the electronics is reduced. The at least one flexible membrane or diaphragm also causes the internal volume of the cooling circuit to be adapted automatically to the variable volume of the cooling medium that is present in the cooling circuit, so that the creation of gas bubbles in the cooling medium is prevented, regardless of the operating orientation of the heat exchanger. This makes possible reliable cooling even after the heat exchanger has temporarily assumed an unusual operating orientation, e.g. during transport.
[0009] A particularly preferred embodiment of such a heat exchanger is to join a heat exchanger to an equalizing vessel in a single module, incorporating a coolant filter at an interface therebetween. It prevents, at very low cost, problems and damage due to contaminants in the cooling medium.
[0010] The preferred refinement, according to which the filter is a plastic part directly attached to a housing of the equalizing vessel, yields a compact, robust, and cost-saving design.
BRIEF FIGURE DESCRIPTION
[0011] Further details and advantageous refinements of the invention are evident from the exemplifying embodiments, in no way to be understood as limitations of the invention, that are described below and depicted in the drawings.
[0012] FIG. 1 is a schematic depiction showing, by way of example, a heat exchanger according to the invention and its arrangement in a cooling circuit;
[0013] FIG. 2 is an enlarged depiction of detail II of FIG. 1 ;
[0014] FIG. 3 is an enlarged depiction of detail III of FIG. 1 ;
[0015] FIG. 4 is an enlarged depiction of detail IV of FIG. 1 ;
[0016] FIG. 5 is a three-dimensional depiction, shown partially in section, of an exemplifying embodiment according to the invention;
[0017] FIG. 6 is a depiction analogous to FIG. 5 , viewed in the direction of arrow VI of FIG. 5 ;
[0018] FIG. 7 is a three-dimensional depiction of the membrane used in the heat exchanger according to FIGS. 1 to 6 and of the spring element joined to it; and
[0019] FIG. 8 shows a second exemplifying embodiment of the invention;
[0020] FIG. 9 is an overview of a second exemplifying embodiment of the invention;
[0021] FIG. 10 is a section viewed along line X-X of FIG. 11 ;
[0022] FIG. 11 is a top view looking in the direction of arrow XI of FIG. 10 ;
[0023] FIG. 12 is an enlarged depiction of detail XII of FIG. 10 ;
[0024] FIG. 13 is a three-dimensional depiction of a heat exchanger 130 ′ that is equipped with an integrated large-area filter;
[0025] FIG. 14 is an enlarged depiction of detail XIV of FIG. 13 ;
[0026] FIG. 15 is a section through the upper part of heat exchanger 120 ′ depicted in FIG. 13 ;
[0027] FIG. 16 is a section analogous to FIG. 15 ; in this variant, filter 170 is arranged and mounted differently than in FIG. 15 ; and
[0028] FIG. 17 is a sectioned detail depiction of the filter and the seal from FIG. 16 .
DETAILED DESCRIPTION
[0029] FIG. 1 schematically shows a heat exchanger 20 . The latter has, in known fashion, flat cooling tubes 22 through which a cooling medium 24 flows during operation, and which are joined in thermally conductive fashion to cooling plates 26 arranged in a zigzag shape.
[0030] The spaces between the flat tubes 22 are closed off at the top in liquid-tight fashion by closure panels 28 , thus creating an upper tank 30 that is subdivided by a vertical partition 32 into an inflow-side chamber 34 and an outflow-side chamber 36 .
[0031] The spaces between tubes 22 are likewise closed off at the bottom in liquid-tight fashion by closure panels 38 , so that a lower tank 40 is formed there.
[0032] Upper tank 30 is joined in liquid-tight fashion to heat exchanger 20 by means of a crimped join 44 . It has an upper wall 46 ( FIG. 3 ) that is implemented here integrally with partition 32 . Apertures are located in said wall, namely an aperture 48 above outflow-side space 36 and an aperture 50 above inflow-side space 34 .
[0033] These apertures 48 , 50 are hermetically closed off in liquid-tight fashion on their upper sides by a flexible membrane 54 on which rests a flat spring arrangement 56 made of non-corroding spring steel. This spring arrangement 56 is joined to membrane 54 , for example, by vulcanization. For this purpose, spring arrangement 56 can also be vulcanized into membrane 54 in order to protect it particularly well from corrosion.
[0034] Diaphragm 54 and spring arrangement 56 are retained in fluid-tight fashion at their outer rim by the rim 58 of a cover 60 . They are likewise retained at the center by a strut 61 of cover 60 (cf. FIG. 3 ). Air or an inert gas, e.g. nitrogen, is present in space 62 between cover 60 and membrane 54 .
[0035] Upper tank 30 has an inflow 64 , and through the latter cooling medium (hereinafter “coolant” for short) 24 flows in the direction of an arrow 66 to inflow-side chamber 34 . From there, it flows downward through passages or tubes 22 located there to lower tank 40 , and from the latter through the left-hand (in FIG. 1 ) tubes 22 upward to outflow-side chamber 36 , i.e. the flow follows a switchback or two-direction-flow path. The flow direction can, of course, be the reverse in some cases.
[0036] From there the cooling medium flows through an outflow 68 , in the direction of an arrow 70 , to a heat sink 74 that is joined in thermally conductive fashion to an electronic component 76 that is arranged on a circuit board 78 and is supplied with current through the latter.
[0037] The cooling medium is heated in heat sink 74 , and the heated cooling medium is delivered back to inflow 66 by means of a circulating pump 82 driven by an electric motor 80 .
[0038] Heat exchanger 20 is cooled by air by means of a fan 84 , this being indicated only very schematically.
[0039] FIGS. 5 to 7 show the construction of spring arrangement 56 . The latter is formed by the fact that a left-hand spiral-shaped aperture 90 and a right-hand spiral aperture 92 are incorporated into a thin sheet of spring steel, thereby creating at the left a larger spiral spring 94 that is associated with larger chamber 36 , and at the right a smaller spiral spring 96 that is associated with smaller chamber 34 .
[0040] Chambers 34 , 36 are filled with cooling medium 24 up to membrane 54 . When said medium expands, membrane 54 bulges upward above apertures 48 , 50 ; springs 94 , 96 prevent membrane 54 from protruding and being damaged at individual locations.
[0041] When cooling medium 24 contracts, membrane 54 bulges downward through apertures 48 , 50 ; here again, springs 94 , 96 ensure uniform deflection.
[0042] A reliably functioning equalizing vessel 30 is thereby obtained with little complexity.
[0043] In FIG. 7 the deflections described are depicted symbolically by arrows 100 , 102 (upward) and 104 , 106 (downward).
[0044] FIG. 8 shows an equalizing vessel 110 that has only a single connector 112 through which coolant flows in or out during operation. Vessel 110 has at the bottom a cup 114 at whose upper end is provided an outwardly projecting flange 116 in which an annular groove 118 is located. Engaging into the latter is a sealing bead 120 belonging to an elastic membrane 121 , which bead is pressed sealingly into annular groove 118 by a cover 122 . The mounting of cover 122 on cup 114 is not depicted because it is known.
[0045] Elastic membrane 121 is pressed downward at its center, in the manner shown, by a plunger 126 acted upon by a spring 124 . Plunger 126 projects at the top through an opening 128 in cover 122 and is equipped there with a scale 130 for pressure indication. This plunger 126 facilitates venting, e.g. after a repair. Here as well, the space beneath membrane 121 is filled completely with coolant, i.e. with no air bubbles.
[0046] FIGS. 9 to 12 show a second, preferred exemplifying embodiment of the invention. Parts identical or functioning identically to those in FIGS. 1 to 8 are usually labeled with the same reference characters as therein, and are not described again.
[0047] FIG. 9 is an overview image analogous to FIG. 1 . The heated cooling fluid from heat absorber 74 is delivered via a conduit 66 to inflow 64 of heat exchanger 120 , where it is cooled. From outflow 68 , it flows via a conduit 70 to a unit 140 . The latter contains a circulating pump for the cooling fluid (analogous to pump 82 of FIG. 1 ) and a fan (analogous to fan 84 of FIG. 1 ) to generate cooling air for heat exchanger 120 . In contrast to FIG. 1 , the fan and the circulating pump are driven by the same electric motor (cf. e.g. the Assignee's WO2004/031588A1, ANGELIS et al., whose U.S. phase is U.S. Ser. No. 10/527,471, published as US-2006-032 625-A.
[0048] Cooling channels 22 , cooling plates 26 , etc. are configured in the same way as in the first exemplifying embodiment according to FIGS. 1 to 8 .
[0049] As shown particularly well by FIG. 12 , heat exchanger tank 130 is manufactured from a thermoplastic by injection molding.
[0050] This tank 130 has an inwardly projecting flange 48 , and in a second injection-molding step a flexible membrane 154 made of TPE (thermoplastic elastomer) is molded, as a soft component, onto the upper side of this flange 48 . This method is also referred to as two-component injection molding. The seam is labeled 155 .
[0051] Thermoplastic silicone elastomers that are made up of a two-phase block copolymer (polydimethylsiloxane/urea copolymer) are preferably suitable for membrane 154 . A TPE-A (polyether block amide) can also be used if applicable.
[0052] Because the strength of the join between the thermoplastic material of tank 130 and the molded-on TPE of membrane 154 is not very high in the region of joining seam 156 , cover 60 is used as additional security; this has a downwardly projecting portion 158 ′ that rests with pressure on the welded-on rim of membrane 154 in region 156 , i.e. along the entire periphery of membrane 154 .
[0053] For this purpose, outer rim 158 of cover 60 is joined to upper rim 160 of tank 130 , e.g. by laser welding, adhesive bonding, bolting, or by way of a latching join. FIG. 12 shows a join by means of a notch 166 and a projecting rim 168 , which are joined by laser welding. Laser welding results, in space 162 between cover 60 and membrane 154 , in an enclosed air cushion that braces membrane 154 toward the top and thereby relieves mechanical stress.
[0054] If too much oxygen diffuses into the cooling system through the plastic walls, it oxidizes the corrosion inhibitors contained in the coolant and gas bubbles may form; this can result in malfunctions in the cooling system and in some cases even a failure of the cooling system. If too much coolant diffuses outward through the plastic walls, at some time during the required service life (often approx. 60,000 hours) there will be too little coolant remaining in the system for it to continue functioning, and a failure then likewise occurs.
[0055] These requirements, in addition to the temperature and strength demands, limit the suitable materials.
[0056] Appropriate basic materials (hard components) for tank 130 are: polyphenylene oxide (PPO), glass-fiber reinforced; optionally also polypropylene (PP), likewise glass-fiber reinforced. Particularly suitable on the basis of present knowledge, in view of the requirement of very low permeability for water, glycol, or another coolant outward from the cooling circuit on the one hand, and for oxygen from outside into the coolant on the other hand, is polyphenylene sulfide (PPS), glass-fiber reinforced; or PA-HTN, a temperature-stabilized polyamide, likewise glass-fiber reinforced.
[0057] PA is very well suited for laser welding, PPS somewhat less so. PA is therefore preferred when suitable, including for price reasons.
[0058] What is achieved by means of the invention is that heat exchanger 120 can simultaneously also work as an equalizing vessel to allow the equalization of changes in the volume of cooling liquid; such changes are inevitable during extended operation, and can also occur as a result of temperature fluctuations.
[0059] FIG. 13 shows a heat exchanger 120 ′ having an integrated filter 170 . According to FIG. 14 , this filter 170 has filter openings 172 that, for example, can be larger on inflow side 36 (on the right in FIG. 13 ) than on outflow side 34 , in order to achieve firstly coarse filtration and then fine filtration. The portion of filter 170 that performs the coarse filtration could also be referred to as a sieve.
[0060] Filter 170 can be made of metal or plastic, and according to FIG. 15 is mounted on the lower side of vessel 130 ′, e.g. using the two-component injection molding method.
[0061] FIG. 16 shows an alternative in which filter 170 is joined to seal 44 a to form one module. This can be achieved, for example, by vulcanization. Alternatively, and particularly economically, it is possible e.g. to injection-embed filter 170 in TPE using the injection molding method. In both cases, assembly is simplified, and a very robust heat exchanger is obtained.
[0062] In the region of inflow 36 , filter 170 filters cooling medium that flows via inlet 64 into vessel 130 ′ and from there downward into flat tubes 22 of heat exchanger 20 . Coarse dirt is thereby held back on the right side of filter 170 .
[0063] The cooling medium then flows through the left half of flat tubes 22 from bottom to top, being filtered by the left half of filter 170 so that coolant, which has been filtered twice, flows through outflow 68 to pump 140 ( FIG. 9 ).
[0064] This is important because pump 140 is very sensitive to contaminants in the coolant, and therefore must be particularly well protected, since contaminants could cause pump 140 to seize.
[0065] From pump 140 , the coolant flows (according to FIG. 9 ) to heat absorber 74 and from there back to inlet 64 .
[0066] The result of the large filter area, in the context of this innovative arrangement, is that the pressure drop at filter 170 becomes very low.
[0067] When a heat absorber that has been machined in chip-removing fashion is used, the machining chips that are created cannot be completely removed without reducing the efficiency of heat absorber 74 .
[0068] In heat exchanger 20 as well, residual chips and dirt particles cannot be avoided during the manufacturing process, but at best can be reduced by soldering it under vacuum and then thoroughly rinsing and cleaning it.
[0069] The entry of dirt into the coolant circuit, during filling with coolant and subsequent testing, likewise cannot be entirely avoided.
[0070] The consequence is that chips and dirt might clog the small-scale structures in the heat absorber and thereby reduce efficiency. The danger also always exists that dirt particles may get into a narrow gap in pump 140 and thus cause blockage of the pump.
[0071] Such problems are eliminated by the invention. It is particularly advantageous that the invention yields a large filter area, and an additional filter housing can thus be eliminated. In the liquid circuit, chips and dirt particles that become detached in the heat absorber and heat exchanger are reliably held back on the outflow side at filter 170 before they flow into pump 140 . The large filter area, relative to the amount of dirt that occurs, prevents clogging of the filter and an excessive pressure drop in the cooling medium in the circuit.
[0072] The invention therefore eliminates the need to provide a separate filter housing along with hose connections, thus reducing costs. In addition, no space is required for a separate filter housing and the requisite hose connections, enabling a compact design. Lastly, with the filter arranged as depicted (i.e. in the heat exchanger tank), chips that become detached from heat absorber 74 and heat exchanger 20 cannot get into pump 140 , since the latter is arranged in the flow direction after heat exchanger 20 and before heat absorber 74 . At no other location in the overall system, moreover, could the filter area be made so large without substantial additional cost. Clogging of the small-scale structures of heat absorber 74 is therefore prevented or greatly reduced in simple fashion, as is blockage of circulating pump 140 .
[0073] An equalization vessel that is separate from the heat exchanger could of course also be manufactured using the same principle, for example if the volume of the heat exchanger is limited for space reasons. In other ways as well, many variants and modifications are possible within the scope of the present invention.
[0074] FIG. 17 is a sectioned detail depiction of filter 170 and seal 44 a of FIG. 16 . Upon installation of filter 170 into heat exchanger 20 , seal 44 a is preferably deformed in order to produce a good seal (cf. FIG. 16 ).
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A heat exchanger serves to cool a cooling medium, which in turn is intended to cool an electronic component ( 76 ). The heat exchanger has an inflow ( 64 ) for delivery of hot coolant, and an outflow ( 68 ) for discharge of coolant cooled in the heat exchanger. An equalizing vessel ( 30 ) is joined to the heat exchanger to form one module. The vessel serves to equalize changes in coolant volume. The equalizing vessel ( 30 ) is closed off by a flexible membrane ( 54 ) which follows such changes in volume. The equalizing vessel ( 30 ) is implemented as a component of the coolant circuit. One part of the equalizing vessel is implemented as a component of the inflow ( 64 ) and another part as a component of the outflow ( 68 ), which parts are in liquid communication with one another via a switchback path through passages ( 22 ) within the heat exchanger ( 20 ) that is implemented in double-flow fashion.
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This application claims the benefit of U.S. Provisional Application No. 60/073,240, filed Jan. 30, 1998, and is a continuation application of U.S. application Ser. No. 09/238,248, filed Jan. 27, 1999, now U.S. Pat. No. 6,196,134, the entire disclosure of which is incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to railcar trucks and more particularly to a lightweight railcar truck bolster.
2. Description of the Related Art
Railcar trucks are the wheeled vehicles that ride on the tracks and support the railcar body. Two trucks are normally used beneath each car body. Each truck includes wheel sets which includes two wheels spaced transversely from each other and joined by a transversely extending axle. Journal bearings are pressed onto each of the axle. Transversely spaced side frames are supported on the wheel sets. The side frames are longitudinally elongated and define longitudinally spaced, downwardly opening pedestal jaws. Bearing adapters are mounted in the jaws and the adapters rotatably receive the wheel set journal bearings. The wheel sets and side frames are mounted together by the bearing adapters.
Transversely extending between each side frame is a truck bolster. The truck bolster includes a center bowl and two opposed, elongated bolster arms that extend transversely outward from beneath the center bowl. The arms and the bolster overall, are formed of a top plate, also known as a compression member, a bottom plate, also known as a tension member, and two upright structural or side walls. The bolster arms extend outward a length such that in service, the bolster arms extend through bolster arm openings in the side frames. The truck bolster is mounted on helical springs which are also mounted in the bolster arm openings and supported on the side frames. The helical springs support the weight of the railcar and payload and cushion the shock caused by uneven railroad track.
The Association of American Railroads (“A.A.R.”) sets forth structural requirements for truck bolsters. These requirements include the truck bolster being strong enough to support the weight of the railcar and its payload and also exhibit fatigue resistant capabilities for extended service of the bolster. Because the railcar truck bolsters must exhibit high strength, truck bolsters are conventionally made of cast steel and contribute a significant part of the total weight of the railway car. In the rail line shipping industry, weight limits are placed on shippers of goods for preserving the safety and conditions of the track. Consequently, the quantity of goods that may be placed in or on a railcar is affected by the weight of the railcar body, the trucks and other railcar components. Thus, a reduction in the weight of the railcars, including the truck bolster, will result in an increase in the total capacity of goods shipped by a rail line owner. Therefore, it is highly desirable to reduce the weight of the truck bolster while at the same time maintaining the strength and fatigue resistance capabilities of the bolster.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to reduce the weight of a railway car by reducing the overall weight of the truck bolster. It is another object of the invention to reduce the weight of the truck bolster without a decrease in strength or fatigue resistance.
Briefly, the present invention involves removing metal from the compression and tension members of the truck bolster and locating a pair of vertical ribs on opposing sides of the bolster center bowl. The vertical ribs extend from the tension member to the compression member. The compression member has a wall thickness that is thinner than conventional bolsters near the center bowl and gradually increases in thickness from the center bowl to the ends of the bolster arms. Likewise, the tension member has a wall thickness that is thinner near the center of the bolster and which gradually increases in thickness toward the ends of the bolster arms. Both the tension and compression members are continuous without lightener holes. To compensate for the loss of material and resulting strength in the compression and tension members, the transversely extending vertical ribs are added on opposing sides of the center bowl to provide the required structural strength to the bolster. Significantly, the disclosed bolster is lighter than conventional truck bolsters, thereby creating an increase in the total capacity of goods that can be shipped by rail line owners. Specifically, the weight of the disclosed bolster has been reduced by over 230 pounds, translating into a weight reduction of over 46,000 pounds for a typical 100-car train. This significant weight reduction, in turn, translates into a significant increase in goods which may be shipped by rail line owners.
In addition, the disclosed light weight truck bolster is cast from a one-piece bolster core which offers several manufacturing advantages. Traditionally, three to five core pieces were used which led to problems during the pouring process, such as, core shifting. Core shifting, in turn, led to dimensional inconsistencies and greater wall thicknesses which, consequently, led to an increase in the weight of the bolster. These problems are eliminated with a one-piece core. Also with a one-piece core, the bolster wall thickness can be reduced without the possibility of multi-core shifting which, in the past, has created walls that were too thin. Moreover, in addition to the increased manufacturing efficiency with a one-piece core, chaplets which typically were used to support multi-cores are no longer needed to support the cores. Instead, the mold supports the one-piece core. Without the use of chaplets, associated problems, such as, the creation of stress concentrations and removal of chaplet scars in finishing are eliminated. Moreover, significant savings in the costs associated with finishing the bolsters are realized.
The full range of objects, aspects and advantages of the invention are only appreciated by a full reading of this specification and a full understanding of the invention. Therefore, to complete this specification, a detailed description of the invention and the preferred embodiments follow, after a brief description of the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiments of the invention will be described in relation to the accompanying drawings. In the drawings, the following figures have the following general nature:
FIG. 1 is a side elevation view of the truck bolster of the present invention.
FIG. 2 is a half-top plan view and a half-bottom plan view of the invention of FIG. 1 .
FIG. 3 is a cross-section view of the invention of FIG. 2 taken along lines 3 — 3 .
In the accompanying drawings, like reference numbers are used throughout the various figures for identical structures.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-3, there is depicted a preferred embodiment of a light weight truck bolster that meets the A.A.R. structural qualifications for truck bolsters while weighing significantly less than traditional truck bolsters. The preferred truck bolster 10 comprises a center bowl 12 , two opposed, elongated bolster arms 14 and 16 that extend transversely outward from beneath the center bowl. The arms and the bolster overall, are formed of a compression member 18 , a tension member 20 , and two upright structural or side walls 22 . The compression and tension members, and side walls form and define a bolster cavity 23 . To facilitate manufacture, reduce weight and enable mounting brakes and side bearings, lightener holes 24 are located within the side walls 22 on each bolster arm 14 and 16 . The bolster also has a center bore 40 for receiving a king pin to connect the truck to the railcar body. Bolt holes 42 are located near the ends of the bolster arms for mounting side bearings to the bolsters.
In a preferred embodiment of the tension and compression members, the wall thickness of each has been reduced. Specifically, metal has been removed in the tension member 20 below the center bowl 12 and generally along the entire compression member. As shown in FIG. 1, the preferred thickness of the tension member wall 44 has been reduced to approximately {fraction (15/16)} of an inch. This preferred thickness is constant below the center bowl region and gradually increases from the center bowl region toward the end of the bolster arms 14 and 16 with the maximum thickness being over the turn 26 of the spring seat, a location of high stress concentration. At this turn, the thickness increases to a preferable 1½ inches. The preferred thickness of the tension member then gradually decreases toward the end of the bolster arms 14 and 16 to approximately 1{fraction (1/16)} inches.
Metal has also been removed in the compression member 18 in the area below the center bowl 12 . The preferred thickness of the compression member wall 46 immediately below the center bowl has been reduced to approximately 1¼ inches. The preferred thickness has been further reduced in the bolster arms to approximately ¾ of an inch. The preferred thickness remains constant along the bolster arms with a gradual increase in thickness toward the turn 26 of the spring seat. At this turn, the thickness increases to a preferable 1{fraction (3/16)} inches. Again, the preferred thickness of the compression wall 46 gradually decreases toward the end of the bolster arms 14 and 16 to approximately ⅞ of an inch. Variations to the above preferred thicknesses of the tension and compression members are contemplated and considered within the scope of the present invention.
Also in a preferred embodiment of the tension and compression members, lightener holes previously in the tension and compression members have been removed. With the removal of the lightener holes, previous metal flow problems, such as the creation of vertices and stress concentrations, are eliminated. The king pin hole and side bearing bolt holes on the compression member are retained.
In traditional bolsters, two longitudinal ribs were needed and were located within each bolster arm above and below the lightener holes in the tension and compression members, respectively, and running uninterrupted the entire length of the bolster arm. Also with traditional bolsters, transverse ribs were located below the center bowl extending upward approximately 5 inches from the inside of the tension member. A preferred bolster 10 has only one longitudinal rib 48 in each bolster arm end and a transverse rib 30 on each side of the center bowl 12 that extends the full height of the side walls 22 , from the tension member 20 to the compression member 18 . The transverse ribs 30 located on each side of the center bowl are connected by a pair of longitudinal rib connecting walls 31 . As shown in FIG. 3, the rib walls 31 increase in thickness from the tension member 20 to the compression member 18 . Structural cross ribs 33 transverse the rib walls 31 and are located between the transverse ribs 30 and provide structural support for the rib walls 31 .
The longitudinal rib 48 extends from the tension member 20 to the compression member 18 and the free edge defines a curvature 56 . The curvature 56 allows the rib 48 to form into the tension and compression member eliminating the sharp transition between the rib 48 and the members 18 and 20 . The gradual transition of the rib 48 into the compression and tension members reduces the potential stress concentrations that would typically occur at sharp transitions between adjoining cast members.
At the junction 32 where the transverse rib 30 forms with the tension member 20 , the rib wall thickness is reduced and small radii 34 are formed between the rib wall and the tension member 20 to prevent shrink in the casting at that junction. The transverse rib 30 has opposite faces 50 and 52 . The face 50 throughout the entire height of the wall, is generally perpendicular to the plane of the compression member. The face 52 throughout the entire height of the wall is angled from the tension member to the compression member. This angled face of the rib wall results in the transverse rib 30 having an increase in wall thickness from the junction 32 to the point at which the rib 30 joins with the compression member 18 .
The preferred bolster 10 with the longitudinal ribs 48 located near the bolster arm ends and the transversely extending ribs 30 located near the center bowl creates bolster arms that define an empty hollow space 54 , that is, without metal support ribs or gussets in the bolster arms. The empty hollow space 54 is formed by the compression and tension members, the side walls, and the transverse and longitudinal ribs. With the exception of the aforementioned improvements to the truck bolster, the remainder of the bolster is conventional.
Significantly, with the preferred bolster 10 , a one-piece bolster core is used to manufacture the bolster casting. Traditionally, three to five core pieces were used which led to problems during the pouring process, such as, core shifting, which, in turn, led to casting flaws, offsets and dimensional inconsistencies. Stress concentrations develop at these casting flaws and offsets and are typically a primary reason for metal fatigue. With a one-piece core, the bolster is significantly easier to manufacture, resulting in an increase in production efficiency, and the problems associated with core shifting and resulting stress concentrations are eliminated. In addition, with the one-piece core, no chaplets are needed to support the core. Instead, the mold supports the core eliminating problems such as stress concentrations around the chaplet and chaplet scars or fusion of the chaplets to the casting. In addition, finishing of the chaplet scars is no longer required.
The preferred embodiments of the invention are now described as to enable a person of ordinary skill in the art to make and use the same. Variations of the preferred embodiment are possible without being outside the scope of the present invention. Therefore, to particularly point out and distinctly claim the subject matter regarded as the invention, the following claims conclude the specification.
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There is disclosed a light weight truck bolster for railway car trucks. Metal has been removed in the compression and tension members of the bolster near the center bowl. One longitudinal rib is located in each end of the bolster arms and a pair of transversely extending vertical ribs are located on opposing sides of the center bowl and extend from the tension member to the compression member. The disclosed light weight truck bolster satisfies the Association of American Railroads (“A.A.R.”) design qualifications for truck bolsters while weighing significantly less than traditional truck bolsters.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-173649, filed on Jun. 14, 2002, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a semiconductor device, and more particularly, it relates to a semiconductor device which has a lateral type or vertical type field effect transistor structure, and is suitably applied as a device for high-speed switching or a device for power control.
[0003] As the supply voltage for CPUs decreased, the power supply with the synchronous rectification system using a field effect transistor is being greater used.
[0004] [0004]FIG. 19 is a schematic diagram showing the cross-sectional structure of MOSFET (Metal-oxide-Semiconductor Field Effect Transistor) used for such a power supply. Hereafter, a n channel type will be explained. It is also possible to acquire the similar structure about p channel type by reversing p type and n type for each semiconductor part.
[0005] This MOSFET has the so-called “vertical type” structure, where n type semiconductor region 104 is provided on n + type substrate 102 , and p type base regions 106 are selectively formed on the surface of the n type semiconductor region 104 . Moreover, n + type source region 108 is selectively formed on the surface of the p type base region 106 , and a gate oxide film 110 and a gate electrode 112 are formed on the p type base region 106 and n− type semiconductor region 104 between the n + type source region 108 and the neighboring n + source region 108 .
[0006] The source electrode 114 is connected to n + type source region 108 , and the drain electrode 116 is connected to the back side of n + type substrate 102 . By applying a bias voltage to the gate electrode 112 , a channel can be formed on the surface of p + type base region 106 , and a current can be passed between the source and the drain.
[0007] However, in the semiconductor device illustrated in FIG. 19, since the facing area between the gate and the drain is large, and since the gate and the drain have countered through gate oxide 110 , the feedback capacitance between the gate and the drain is large. This feedback capacitance is one of the parameters which impede high-speed operation of the semiconductor device and increase switching loss. Therefore, it is desirable to reduce the feedback capacitance between the gate and the drain.
[0008] On the other hand, narrowing the interval between p type base regions 106 and 106 may also be considered so that the facing area between a gate and a drain may be reduced. However, in this case, since the current path between drain and source is constricted, the JFET resistance RJ corresponding to resistance of this current path becomes high, and electrical connection loss increases.
[0009] As mentioned above, in the conventional MOSFET, there was a relation of a trade-off between ON resistance and the feedback capacitance, and there was a problem that there was a limit in reducing high-speed operation, electrical connection loss, and switching loss.
SUMMARY OF THE INVENTION
[0010] According to an embodiment of the invention, there is provided a semiconductor device comprising: a semiconductor layer of a first conductivity type; a pair of base regions of a second conductivity type selectively provided on a surface of the semiconductor layer; source regions of a first conductivity type, each of the source regions being selectively provided on a surface of each of the base regions; an electrical field reducing region of a second conductivity type selectively provided on the surface of the semiconductor layer between the pair of the base regions; a gate insulating film provided on the surface of the base regions; a pair of gate electrodes provided on the gate insulating film, each of the gate electrodes being provided on the surface of the base regions between the source region and the electrical field reducing region; and a source electrode connected to the source regions, the electrical field reducing region being isolated from both of the gate electrode and the source electrode.
[0011] According to other embodiment of the invention, there is provided a semiconductor device comprising: a semiconductor layer of a first conductivity type; a plurality of base regions of a second conductivity type provided on a surface of the semiconductor layer in a matrix fashion; a plurality of source regions of a first conductivity type, each of the source regions being selectively provided on a surface of each of the base regions; a plurality of electrical field reducing regions of a second conductivity type, each of the electrical field reducing regions being selectively provided on the surface of the semiconductor layer between the base regions; a gate insulating film provided on the surface of the base regions; a gate electrode provided on the gate insulating film, the gate electrode having a lattice pattern in order to selectively cover the surface of the base regions between each of the source regions and each of the electrical field reducing regions; and a source electrode connected to the source regions.
[0012] According to other embodiment of the invention, there is provided a semiconductor device comprising: a semiconductor layer of a first conductivity type; a pair of base regions of a second conductivity type provided on a surface of semiconductor layer; a pair of source regions of a first conductivity type, each of the source regions being selectively provided on a surface of each of the base regions; an electrical field reducing region of a second conductivity type selectively provided on the surface of the semiconductor layer between the base regions; semiconductor regions of a first conductivity type between the electrical field reducing region and each of the base regions, the semiconductor regions having an impurity concentration higher than the semiconductor layer; a gate insulating film provided on the surface of the base regions; a pair of gate electrodes provided on the gate insulating film, each of the gate electrodes being provided to selectively cover the surface of each of the base regions between each of the source regions and the electrical field reducing region; and a source electrode connected to the source regions, the electrical field reducing region being connected to the source electrode and being isolated from the gate electrode.
[0013] According to other embodiment of the invention, there is provided a semiconductor device comprising: a semiconductor layer of a first conductivity type; a pair of base regions of a second conductivity type provided selectively on a surface of the semiconductor layer; a pair of source regions of a first conductivity type, each of the source regions being provided selectively on a surface of each of the base regions; a metal layer in contact with the surface of the semiconductor layer between the base regions; a gate insulating film provided on the surface of the base regions; a gate electrode provided on the gate insulating film to selectively cover the surface of the base regions between each of the source regions and the metal layer; and a source electrode connected to the source regions, the metal layer forming a Schottky junction with the semiconductor layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention will be understood more fully from the detailed description given herebelow and from the accompanying drawings of the embodiments of the invention. However, the drawings are not intended to imply limitation of the invention to a specific embodiment, but are for explanation and understanding only.
[0015] In the drawings:
[0016] [0016]FIG. 1A is a sectional view of the semiconductor device showing the fundamental concept of the first embodiment of the invention;
[0017] [0017]FIG. 1B is a sectional view of the semiconductor device showing another example of the fundamental concept of the first embodiment of the invention;
[0018] [0018]FIG. 2A is a schematic diagram which illustrates the superficial arrangement relation of each part in the surface of the semiconductor layer, and this X-X′ line section corresponds to FIG. 1A;
[0019] [0019]FIG. 2B is a schematic diagram which illustrates the superficial arrangement relation of each part in the surface of the semiconductor layer, and this X-X′ line section corresponds to FIG. 1B;
[0020] [0020]FIG. 3 is a sectional view of the semiconductor device for explaining the fundamental concept of a second embodiment of the invention;
[0021] [0021]FIG. 4 is a sectional view showing the first example of the semiconductor device of the invention;
[0022] [0022]FIG. 5 is a sectional view showing the second example of the semiconductor device of the invention;
[0023] [0023]FIG. 6 is a sectional view showing the third example of the semiconductor device of the invention;
[0024] [0024]FIG. 7 is a sectional view showing the fourth example of the semiconductor device of the invention;
[0025] [0025]FIG. 8A is a schematic diagram showing the plane structure of the fifth example of the semiconductor device of the invention;
[0026] [0026]FIG. 8B is a schematic diagram showing the plane structure of a modification of the fifth example of the semiconductor device of the invention;
[0027] [0027]FIG. 8C is a schematic diagram showing the plane structure of another modification of the fifth example of the semiconductor device of the invention;
[0028] [0028]FIG. 9A is the X-X′ line sectional view of FIG. 8A;
[0029] [0029]FIG. 9B is the X-X′ line sectional view of FIG. 8B;
[0030] [0030]FIG. 9C is the X-X′ line sectional view of FIG. 8C;
[0031] [0031]FIG. 10 is a schematic diagram showing the plane structure of the sixth example of the semiconductor device of the invention;
[0032] [0032]FIG. 11 is a schematic diagram showing the plane structure of the seventh example of the semiconductor device of the invention;
[0033] [0033]FIG. 12 is a schematic diagram which illustrates the cross-sectional structure of the eighth example of the semiconductor device of the invention;
[0034] [0034]FIG. 13 is a schematic diagram which illustrates the cross-sectional structure of the ninth example of the semiconductor device of the invention;
[0035] [0035]FIG. 14 is a schematic diagram showing the plane structure of the tenth example of the semiconductor device of the invention;
[0036] [0036]FIG. 15 is the X-X′ line sectional view of FIG. 14;
[0037] [0037]FIG. 16 is the Y-Y′ line sectional view of FIG. 14;
[0038] [0038]FIG. 17 shows the parasitic NPN transistor TRp which consists of the p type base region 6 , the n + type source region 8 , and the n type epitaxial layer 4 exists in the conventional MOSFET;
[0039] [0039]FIG. 18 shows the inductance L made into load; and
[0040] [0040]FIG. 19 is a schematic diagram showing the cross-sectional structure of MOSFET (Metal-oxide-Semiconductor Field Effect Transistor) used for such a power supply.
DETAILED DESCRIPTION
[0041] Referring to drawings, some embodiments of the present invention will now be described in detail.
[0042] [0042]FIG. 1A is a sectional view of the semiconductor device showing the fundamental concept of the first embodiment of the invention.
[0043] [0043]FIG. 2A is a schematic diagram which illustrates the superficial arrangement relation of each part in the surface of that semiconductor layer, and this X-X′ line section corresponds to FIG. 1A.
[0044] In the semiconductor device of this embodiment, a n type epitaxial layer 4 is formed on a n + type semiconductor substrate 2 . On the n type epitaxial layer 4 , p type base regions 6 are formed selectively. A n + type source region 8 and a p + type region 9 are formed in this p type base region 6 . Between adjoining p type base regions 6 , the p + type electric field relaxation region 20 is formed at some distance from the p type base region 6 . And in the both sides of the electric field relaxation region 20 , the gate electrodes 12 are formed through the gate oxide film 10 , which reaches the n + type source region 8 .
[0045] As for the impurity concentration of each part, the n + type semiconductor substrate 2 is set to 1×10 19 −1×10 20 cm −3 , and the n type epitaxial layer 4 is set to about 1×10 16 cm −3 in order obtain the breakdown voltage of about 30 volts between the source and the drain, and n type epitacial layer 4 is set to about 3×10 15 cm −3 in order to obtain the breakdown voltage of about 100 volts.
[0046] The impurity concentration of the p type base region 6 can be set to 1×10 16 −5×10 17 cm −3 , and the impurity concentrations of the n + type source region 8 and the p + type region 9 can be set to 1×10 19 −1×10 20 cm −3 . Furthermore, it is desirable to set the impurity concentration of the p + type electric field relaxation region 20 to more than 1×10 17 cm −3 , as will be explained in detail later.
[0047] The circumference of the gate electrode 12 is covered with an insulating layer 13 , and the source electrode 14 is connected to the source region 8 . Moreover, the drain electrode 16 is connected to the back side of the n + type substrate 2 .
[0048] In this embodiment, the p + type electric field relaxation region 20 is not connected with any of the source, drain and the gate electrode, and thus the region 20 is in the state of the so-called “floating”.
[0049] According to the structure explained above, by providing the p + type electric field relaxation region 20 , the facing area between the gate and the drain can be made smaller than the conventional structure shown in FIG. 19. If, in the structure illustrated in FIG. 19, the gate electrode 12 is simply divided and provided in two parts, in the portion of the gap between these divided parts of the gate electrode, the effect or depletion to the JFET region (n type epitaxial layer 4 ) from the gate will decrease. Therefore, the JFET region cannot be depleted, and thus, a problem that the breakdown voltage between the source and the drain falls arises.
[0050] In contrast to this, instead of making the JFET region depleted by applying a bias voltage from the gate electrode 12 , the p + type electric field relaxation region 20 is provided according to the embodiment, and depletion to the JFET region from the electric field relaxation region 20 can be promoted by the function of the p-n junction. By employing such a structure, the breakdown voltage between the source and the drain can be increased, and the capacitance between the gate and the drain can be reduced.
[0051] Furthermore, by making the electric field relaxation region 20 into the state of “floating”, the effect that ON resistance can be lowered is acquired, as will be explained below.
[0052] That is, if the junction depth of the electric field relaxation region 20 is deep, current concentrates between the electric field relaxation region 20 and the p type base regions 6 , and non-negligible resistance may arise in these regions. If the electric field relaxation region 20 and the source electrode 14 are made into the same potential, the regions between the electric field relaxation region 20 and the p type base regions 6 can easily be depleted. If voltage is applied to the drain electrode 16 in the state of ON, the cross-section area of the current path in the regions between the electric field relaxation region 20 and the p type base regions 6 will be decreased by the depletion layers extending from the electric field relaxation region 20 and the p type base regions 6 respectively. Therefore, the ON resistance increases.
[0053] In contrast to this, when the electric field relaxation region 20 is made into “floating” state, the potential of the electric field relaxation region 20 is determined by the overlap capacitance (oxide film capacitance) between the gate electrode and the electric field relaxation region 20 , and by the junction capacitance between the electric field relaxation region 20 and the JFET region.
[0054] Compared with the case where the source electrode 14 and the electric field relaxation region 20 are made into the same potential, the potential of the electric field relaxation region 20 is dragged by the potential of the gate electrode in an ON state, and becomes higher compared with the potential of the source electrode 14 , and depletion from the electric field relaxation region 20 becomes weaker. Therefore, reduction of the cross-section area of the current path in the regions between the electric field relaxation region 20 and the p type base regions 6 can be suppressed, and the effect that ON resistance becomes smaller is acquired.
[0055] In this structure, the junction depth of the electric field relaxation region 20 may preferably be shallower compared with the junction depth of the p type base regions 6 . It is because influence of the resistance in the regions between the electric field relaxation region 20 and the p type base regions 6 can be made smaller if this junction depth becomes shallow enough. In order to prevent the increase of ON resistance, the junction depth of the electric field relaxation region 20 is preferably below smaller than half of the junction depth of the p type base regions 6 . For example, when the junction depth of the p type base regions 6 is made into about one micrometer, as for the junction depth of the electric field relaxation region 20 , it is desirable to make it 0.5 micrometers or less.
[0056] Moreover, as for the electric field relaxation region 20 , it is desirable to set the impurity concentration thereof so that it may not be depleted completely at the time of operation of the device. In order to prevent the complete depletion, it is desirable to make the net dose amount of the electric field relaxation region 20 more than 4×10 12 cm −2 , and to make the impurity concentration thereof more than 1×10 17 cm −3 .
[0057] [0057]FIG. 1B is a sectional view of the semiconductor device showing another example of the fundamental concept of the first embodiment of the invention.
[0058] And FIG. 2B is a schematic diagram which illustrates the superficial arrangement relation of each part in the surface of the semiconductor layer, and this X-X′ line section corresponds to FIG. 1B.
[0059] As shown in these figures, the gate electrode 12 may be formed in one body covering the electric field relaxation region 12 . By forming the gate electrode 12 in such a broader stripe form, the wiring resistance of the gate electrode can be advantageously reduced.
[0060] [0060]FIG. 3 is a sectional view of the semiconductor device for explaining the fundamental concept of a second embodiment of the invention. The same symbols are given to the same elements as what were mentioned above about FIGS. 1A through 2B about this figure, and detailed explanation will be omitted.
[0061] Also in this embodiment, the p + type electric field relaxation region 20 is provided. By employing such a structure, the breakdown voltage between the source and the drain can be increased, and the capacitance between the gate and the drain can be reduced. In this embodiment, further, the electric field relaxation region 20 is connected to the source electrode 14 or the p type base region 6 via the connection path 24 in order to make the electric field relaxation region 20 at the same potential. By employing such a structure, depletion to the JFET region from the electric field relaxation region 20 can be promoted.
[0062] As the result, impurity concentration of a JFET region can be made higher, and when the junction depth of the electric field relaxation region 20 is shallow enough, ON resistance can be lowered. That is, depletion of the JFET region is promoted by providing the connection path 24 and by controlling the potential of the electric field relaxation region 20 . Since the depletion is promoted, impurity concentration of the JFET region can be made higher. With regard to the connection path 24 of this embodiment, various kinds of characteristic structures can be mentioned, as will be explained in full detail later.
[0063] Although the semiconductor region which has p type impurities is illustrated as the electric field relaxation region 20 in FIG. 1A through FIG. 3, the invention is not limited to this. For example, the invention also includes the structure where a Schottky junction formed between a metal and a semiconductor is employed, as will be explained with reference to FIG. 6 later. That is, it is also possible to reduce the capacitance between the gate and the drain similarly by providing a metal layer on the n type epitaxial layer 4 in order to form a Schottky junction, and by extending a depletion region from this junction to the JFET region.
[0064] In the above, the fundamental structures of the semiconductor device of the invention have been explained, referring to FIG. 1A through FIG. 3. Hereafter, some examples of the semiconductor device of these first and the second embodiment will be explained in detail. About the drawings of these examples, the same symbols are given to the same elements as what were mentioned above, and detailed explanation will be omitted.
[0065] Moreover, each example explained below shall contain both features of above-mentioned first and second embodiment, unless reference is especially made. That is, the electric field relaxation region 20 may be in a state of “floating”, or it may be at the same potential with the source region 14 , etc. by providing the connection path 24 appropriately.
[0066] [0066]FIG. 4 is a sectional view showing the first example of the semiconductor device of the invention. In this example, a n type diffusion region 26 is provided so that the p + type electric field relaxation region 20 maybe surrounded thereby. The n type diffusion region 26 has impurity concentration higher than the n type epitaxial layer 4 . Since depletion is promoted near the p + type electric field relaxation region 20 , then type diffusion region 26 where impurity concentration is high can be depleted. Therefore, resistance of the JFET region can be lowered by controlling the increase in the capacitance between the gate and the drain by providing the n type diffusion region 26 with high impurity concentration.
[0067] Moreover, in this example, after forming the gate electrode 12 , the n type diffusion region 26 and the electric field relaxation region 20 can be formed in a self-aligning fashion. That is, the p + type electric field relaxation region 20 and the n type diffusion region 26 with high impurity concentration can be formed by using the gate electrode 12 as a mask and by introducing the n type impurities deeply while introducing the p type impurities shallowly by the methods such as ion implantation.
[0068] [0068]FIG. 5 is a sectional view showing the second example of the semiconductor device of the invention. In this example, a polycrystalline silicon layer 26 containing p type impurities is provided on the semiconductor layer. And p type impurities have diffused near the surface of the n type epitaxial layer 4 from the polycrystalline silicon layer 28 in order to form the p + type electric field relaxation region 20 .
[0069] Like the first embodiment, the polycrystalline silicon layer 2 a may be in a floating state, or may have the same potential as the source electrode 14 like the second embodiment.
[0070] [0070]FIG. 6 is a sectional view showing the third example of the semiconductor device of the invention. In this example, a metal layer 30 is provided on the semiconductor layer. And the depletion region formed by the Schottky junction of the metal and the semiconductor is provided so that it may extend to the JFET region. That is, the effect of depletion by the Schottky junction is used instead of providing the p + type electric field relaxation region 20 . By employing such a structure, the capacitance between the gate and the drain can be reduced.
[0071] And also in this example, like the first embodiment, the metal layer 30 may be in a floating state, or may have the same potential as the source electrode 14 like the second embodiment.
[0072] [0072]FIG. 7 is a sectional view showing the fourth example of the semiconductor device of the invention. This example is similar to the first example mentioned above, and the n type diffusion layer 32 is provided under the p + type electric field relaxation region 20 . The n type diffusion layer 32 has impurity concentration higher than the n type epitaxial layer 4 , and can reduce resistance of the JFET region. And since the depletion is promoted near the electric field relaxation region 20 also in this example, even if the n type diffusion layer 32 is provided, depletion of the JFET region can be achieved to some extent.
[0073] [0073]FIG. 8A is a schematic diagram showing the plane structure of the fifth example of the semiconductor device of the invention. That is, this figure expresses the superficial arrangement relation of each element seen from the surface side of the semiconductor layer.
[0074] And, FIG. 9A is the X-X′ line sectional view of FIG. 8A.
[0075] Under the environment of high-speed operation, the gate resistance also exerts a big influence besides the capacitance between the gate and the drain. The gate resistance can be reduced by transforming the pattern of the shape of a simple stripe which was illustrated in FIGS. 2A and 2B, into the shape as shown in FIG. 8A.
[0076] That is, in the case of this example, the p + type electric field relaxation region 20 is provided in the shape of some islands, as illustrated in FIG. 8A. And the gate electrode 12 has a shape of a “ladder”, where a pair of vertical stripes are connected by the horizontal bars in corresponding to the pattern of the electric field relaxation region 20 . Thus, by appropriately connecting a pair of vertical stripes to form the ladder structure, the wiring resistance of the gate electrode 12 can be reduced and the gate resistance can be lowered.
[0077] Furthermore, in the case of this example, the p + type electric field relaxation region 20 is not made into floating, but connected by providing the terminal area 6 P from the p type base region 6 and made into the same potential. Thus, depletion can be promoted by making the electric field relaxation region 20 into the same potential as the p type base region 6 .
[0078] In addition, in this example, the electric field relaxation region 20 may be short circuited with the source electrode 14 , however it is necessary to provide the electrically conductive material as the connection path 24 in somewhere in that case. Then, the process margin of the connection path 24 and the gate electrode 12 must be kept, and there may be a demerit that the element area may increase. In contrast to this, according to the structure of this example, the potential of the electric field relaxation region 20 is controlled, and depletion can be promoted without increasing element area.
[0079] In addition, as an example of transformation of this example, the structure where the electric field relaxation region 20 is in a floating state without being connected with the p type base region 6 is also included by the range of the invention.
[0080] [0080]FIG. 8B is a schematic diagram showing the plane structure of a modification of the fifth example of the semiconductor device of the invention.
[0081] And FIG. 9B is the X-X′ line sectional view of FIG. 8B.
[0082] In this modification, the gate electrode 12 is formed in one body like the example shown in FIGS. 1B and 2B. The electric field relaxation region 20 is formed in a single stripe pattern and is covered by the gate electrode 12 . By forming the gate electrode 12 in such a broad single stripe form, the wiring resistance of the gate electrode 12 can be advantageously reduced.
[0083] [0083]FIG. 8C is a schematic diagram showing the plane structure of another modification of the fifth example of the semiconductor device of the invention.
[0084] And FIG. 9C is the X-X′ line sectional view of FIG. 8C.
[0085] In this modification, the gate electrode 12 is also formed in one body like the first modification shown in FIGS. 8B and 9B. Further, the electric field relaxation region 20 is formed in a single stripe pattern and has terminal areas 20 is extending to the base regions 6 . That is, instead of providing the terminal areas 6 P as shown in FIGS. 8B and 9B, the terminal areas 20 P are provided in order to connect the electric field relaxation region 20 to the base regions 6 . Thus, the electric field relaxation region 20 can be successfully kept at the same potential as the p type base regions 6 .
[0086] [0086]FIG. 10 is a schematic diagram showing the plane structure of the sixth example of the semiconductor device of the invention. That is, this figure also expresses the superficial arrangement relation of each element in the surface of the semiconductor layer.
[0087] Channel density must be made high in order to reduce channel resistance of FET. The channel density can be increased by forming the base region 6 in the shape of a matrix and arranging the gate electrode 12 in the shape of a lattice corresponding to this, as illustrated in FIG. 10.
[0088] And also in this example, the electric field relaxation regions 20 are provided between the gate electrodes 12 so that the capacitance between gate and drain may be reduced.
[0089] [0089]FIG. 11 is a schematic diagram showing the plane structure of the seventh example of the semiconductor device of the invention. That is, this figure also expresses the superficial arrangement relation of each element in the surface of the semiconductor layer.
[0090] Also in this example, channel density can be increased by arranging the gate electrode 12 in the shape of a lattice. However, in such a lattice-like layout, the electric field may concentrate at the region (region near the center of the figure) surrounded by the portion of the angles of the four n + type source regions 8 . This is because the interval of the p type base -region 6 and the p type base region 6 becomes wide, as seen in the direction of the diagonal.
[0091] Then, in order to reduce the electric field, the p type base region 6 C is formed in the center surrounded by the four source regions 8 . By employing such a structure, points on which the electric field concentrates can be removed and the breakdown voltage between the source and the drain can be improved.
[0092] [0092]FIG. 12 is a schematic diagram which illustrates the cross-sectional structure of the eighth example of the semiconductor device of the invention. That is, this example has a structure of so-called “lateral type” FET, where n + type region 34 is provided on the surface of the n type epitaxial layer 4 and the drain electrode 16 is connected to the surface side. In the case of this structure, as indicated by the arrow D, many components of drain current flow through the n type epitaxial layer 4 .
[0093] Also in such lateral type structures, the same effects as what were mentioned above with reference to FIG. 1A through FIG. 11 can be acquired. Since there are many drain current components which flow through the n type epitaxial layer 4 having a low impurity concentration in the case of this example, although a current is lowered, it is advantageous at the point that the element size can make smaller.
[0094] [0094]FIG. 13 is a schematic diagram which illustrates the cross-sectional structure of the ninth example of the semiconductor device of the invention. That is, this example is also the so-called “lateral type” FET, where the n + type region 36 which penetrates the n type epitaxial layer 4 and reaches the n + layer 2 is provided, and the drain electrode 16 is connected to the surface side. In the case of this structure, the drain current flows to n + type region 36 through the n + type layer 2 .
[0095] Also in such width type structure, the same effects as what were mentioned above with reference to FIG. 1A through FIG. 11 can be acquired. Moreover, in the case of this example, it is advantageous at the point that the drain current can be increased.
[0096] [0096]FIG. 14 is a schematic diagram showing the plane structure of the tenth example of the semiconductor device of the invention. That is, this figure expresses the superficial arrangement relation of each element in the surface or the semiconductor layer.
[0097] [0097]FIG. 15 is its X-X′ line sectional view.
[0098] Furthermore, FIG. 16 is its Y-Y′ line sectional view. FIG. 16 expresses the cross-sectional structure of the region shown in FIG. 14, and the region of the left-hand side which adjoined the region, as will be mentioned later.
[0099] According to the example shown in FIG. 14 through FIG. 16, the amount of avalanche breakdown voltage can be improved. Hereafter, this point will be explained, referring to FIGS. 17 and 18.
[0100] As expressed in FIG. 17, the parasitic NPN transistor TRp which consists of the p type base region 6 , the n + type source region 8 , and the n type epitaxial layer 4 exists in the conventional MOSFET. Here, if MOSFET is changed into an OFF state from an ON state by making the inductance L into load as expressed in FIG. 18, the back electromotive force of the inductance L will be applied between the drain and the source.
[0101] Then, depending on the voltage level, an avalanche breakdown of the diode between the drain and the source may occur. Pairs of an electron and a hole is generated by the avalanche breakdown, and the electrons flow to the drain electrode 16 but the holes flow to the source electrode 14 through the p type base region 6 .
[0102] Then the base and the emitter of the parasitic NPN transistor TRp are biased in a forward direction because current flows to the resistance component R of the p type base region 6 , and the parasitic transistor will be in an ON state.
[0103] When the parasitic NPN transistor TRp turns on only in a part of the element, current concentrates in that part and finally a physical destruction will occur.
[0104] In contrast to this, the avalanche breakdown is made to cause under the p + type electric field relaxation region 20 in this example.
[0105] That is, as expressed in FIGS. 14 and 15, in this example, the p + type electric field relaxation region 20 is substantially formed in the shape of a stripe, and the p type base region 6 is connected to it in the terminal area 6 P. Moreover, in the course from the terminal area 6 P to the source electrode contact SC, the n + type source region 8 is removed.
[0106] With such structure, the hole current flows into the source electrode 14 through the p type base region 6 from the p + type electric field relaxation region 20 , as shown with the arrow. If there is provided the n + source region 8 , the parasitic NPN transistor TRp will be formed. However, the n + type source region 8 is not formed in the region where the electric field relaxation region 20 and the p type base region 6 are connected in this example.
[0107] As the result, on the course of the hole current, a simple diode is only formed and the parasitic NPN transistor is not formed. Therefore, the problem that the parasitic NPN turns on and current concentrates can be avoided. That is, the amount of avalanche breakdown of FET is improved.
[0108] Here, it is desirable to reduce the resistance of the terminal area 6 P which connect the p + type electric field relaxation region 20 and the p type base region 6 so that the hole current become easy to flow. Moreover, it is desirable to make width of the terminal area 6 P wide.
[0109] However, if such modifications are employed, the ON resistance of the semiconductor device goes up, since the JFET region will become narrowed.
[0110] Therefore, in order to suppress the increase of the ON resistance, as expressed to FIG. 14, only some parts of the device instead of the whole device are made into the structure where the amount of avalanche breakdown becomes high, and other parts of the device are made into the usual structure. Then, it is possible to reconcile the amount avalanche breakdown and ON resistance.
[0111] The structure expressed in FIG. 16 is a sectional view showing one of the concrete measures which can lower the breakdown voltages in only a part of the semiconductor device. That is, in this figure, when FETs on both sides are compared, the length L2 of the electric field relaxation region 20 on the right is made longer than the length L1 of the electric field relaxation region 20 on the left.
[0112] Thus, if the electric field relaxation region 20 is made longer, the JFET region becomes harder to be depleted and the breakdown voltage between the source and the drain of the FET can be lowered.
[0113] Therefore, it becomes possible to lower the breakdown voltage of only a part by providing appropriately a part where the length of the electric field relaxation region is made longer in the semiconductor device.
[0114] Heretofore, the embodiments of the present invention have been explained, referring to the examples. However, the present invention is not limited to these specific examples
[0115] For example, the same effect can be acquired also about the structure where the conduction type of each part of the semiconductor which constitutes FET is reversed.
[0116] While the present invention has been disclosed in terms of the embodiment in order to facilitate better understanding thereof, it should be appreciated that the invention can be embodied in various ways without departing from the principle of the invention. Therefore, the invention should be understood to include all possible embodiments and modification to the shown embodiments which can be embodied without departing from the principle of the invention as set forth in the appended claims.
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A semiconductor device comprises: a semiconductor layer of a first conductivity type; a pair of base regions of a second conductivity type selectively provided on a surface of the semiconductor layer; and source regions of a first conductivity type, each of the source regions being selectively provided on a surface of each of the base regions. The semiconductor device further comprises an electrical field reducing region of a second conductivity type selectively provided on the surface of the semiconductor layer between the pair of the base regions; a gate insulating film provided on the surface of the base regions; a pair of gate electrodes provided on the gate insulating film, each of the gate electrodes being provided on the surface of the base regions between the source region and the electrical field reducing region; and a source electrode connected to the source regions. The electrical field reducing region is isolated from both of the gate electrode and the source electrode.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of application Ser. No. 08/567,224 filed Dec. 4 , 1995 .
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to plasma processing. More particularly, the invention is for plasma processing of devices using an inductive discharge. This invention is illustrated in an example with regard to plasma etching or stripping used in the manufacture of semiconductor devices. The invention also is illustrated with regard to chemical vapor deposition (CVD) of semiconductor devices. But it will be recognized that the invention has a wider range of applicability. Merely by way of example, the invention also can be applied in other plasma etching applications, and deposition of materials such as silicon, silicon dioxide, silicon nitride, polysilicon, among others.
[0003] Plasma processing techniques can occur in a variety of semiconductor manufacturing processes. Examples of plasma processing techniques occur in chemical dry etching (CDE), ion-assisted etching (IAE), and plasma enhanced chemical vapor deposition (PECVD), including remote plasma deposition (RPCVD) and ion-assisted plasma enhanced chemical vapor deposition (IAPECVD). These plasma processing techniques often rely upon radio frequency power (rf) supplied to an inductive coil for providing power to gas phase species in forming a plasma.
[0004] Plasmas can be used to form neutral species (i.e., uncharged) for purposes of removing or forming films in the manufacture of integrated circuit devices. For instance, chemical dry etching generally depends on gas-surface reactions involving these neutral species without substantial ion bombardment.
[0005] Ion assisted etching processes, however, rely upon ion bombardment to the substrate surface in defining selected films. Ion bombardment can accelerate gas-surface reaction processes and by doing so can produce highly directional (anisotropic) profiles. But these ion assisted etching processes commonly have a lower selectivity relative to conventional CDE processes. Hence, CDE is often chosen when high selectivity is desired, directionality is not essential and ion bombardment to substrates are to be avoided.
[0006] In other manufacturing processes, ion bombardment to substrate surfaces is often undesirable. This ion bombardment, however, is known to have harmful effects on properties of material layers in devices and excessive ion bombardment flux and energy can lead to intermixing of materials in adjacent device layers, breaking down oxide and “wear out,” injecting of contaminative material formed in the processing environment into substrate material layers, harmful changes in substrate morphology (e.g. amophotization), etc.
[0007] One commonly used chemical dry etching technique is conventional photoresist stripping, often termed ashing or stripping. Conventional resist stripping relies upon a reaction between a neutral gas phase species and a surface material layer, typically for removal. This reaction generally forms volatile products with the surface material layer for its removal. The neutral gas phase species is formed by a plasma discharge. This plasma discharge can be sustained by a coil (e.g., helical coil, etc.) operating at a selected frequency in a conventional photoresist stripper. An example of the conventional photoresist stripper is a quarter-wave helical resonator stripper, which is described by U.S. Pat. No. 4,368,092 in the name of Steinberg et al.
[0008] Referring to the above, an objective in chemical dry etching is to reduce or even eliminate ion bombardment (or ion flux) to surfaces being processed to maintain the desired etching selectivity. In practice, however, it is often difficult to achieve using conventional techniques. These conventional techniques generally attempt to control ion flux by suppressing the amount of charged species in the plasma source reaching the process chamber. A variety of techniques for suppressing these charged species have been proposed.
[0009] These techniques often rely upon shields, baffles, large separation distances between the plasma source and the chamber, or the like, placed between the plasma source and the process chamber. The conventional techniques generally attempt to directly suppress charge density downstream of the plasma source by interfering with convective and diffusive transport of charged species. They tend to promote recombination of charged species by either increasing the surface area (e.g., baffles, etc.) relative to volume, or increasing flow time, which relates to increasing the distance between the plasma source and the process chamber.
[0010] These baffles, however, cause loss of desirable neutral etchant species as well. The baffles, shields, and alike, also are often cumbersome. Baffles, shields, or the large separation distances also cause undesirable recombinative loss of active species and sometimes cause radio frequency power loss and other problems. These baffles and shields also are a potential source of particulate contamination, which is often damaging to integrated circuits.
[0011] Baffles, shields, spatial separation, and alike, when used alone also are often insufficient to substantially prevent unwanted parasitic plasma currents. These plasma currents are generated between the wafer and the plasma source, or between the plasma source and walls of the chamber. It is commonly known that when initial charged species levels are present in an electrical field, the charged species are accelerated and dissociative collisions with neutral particles can multiply the concentration of charge to higher levels. If sufficient “seed” levels of charge and rf potentials are present, the parasitic plasma in the vicinity of the process wafer can reach harmful charge density levels. In some cases, these charge densities may be similar to or even greater than plasma density within the source plasma region, thereby causing even more ion flux to the substrate.
[0012] Charge densities also create a voltage difference between the plasma source and processing chamber or substrate support, which can have an additional deleterious effect. This voltage difference enhances electric fields that can accelerate extraction of charge from the plasma source. Hence, their presence often induces increased levels of charge to be irregularly transported from the plasma source to process substrates, thereby causing non-uniform ion assisted etching.
[0013] Conventional ion assisted plasma etching, however, often requires control and maintenance of ion flux intensity and uniformity within selected process limits and within selected process energy ranges. Control and maintenance of ion flux intensity and uniformity are often difficult to achieve using conventional techniques. For instance, capacitive coupling between high voltage selections of the coil and the plasma discharge often cause relatively high and uncontrollable plasma potentials relative to ground. It is generally understood that a voltage difference between the plasma and ground can cause damaging high energy ion bombardment of articles being processed by the plasma, as illustrated by U.S. Pat. No. 5,234,529 in the name of Johnson. It is further often understood that the rf component of the plasma potential varies in time since it is derived from a coupling to time varying rf excitation. Hence, the energy of charged particles from plasma in conventional inductive sources is spread over a relatively wide range of energies, which undesirably tends to introduce uncontrolled variations in the processing of articles by the plasma.
[0014] The voltage difference between the region just outside of a plasma source and the processing chamber can be modified by introducing internal conductive shields or electrode elements into the processing apparatus downstream of the source. When the plasma potential is elevated with respect to these shield electrodes, however, there is a tendency to generate an undesirable capacitive discharge between the shield and plasma source. These electrode elements are often a source of contamination and the likelihood for contamination is even greater when there is capacitive discharge (ion bombardment from capacitive discharge is a potential source of sputtered material). Contamination is damaging to the manufacture of integrated circuit devices.
[0015] Another limitation is that shields, baffles or electrode elements generally require small holes therein as structural elements. These small holes are designed to allow gas to flow therethrough. The small holes, however, tend to introduce unwanted pressure drops and neutral species recombination. If the holes are made larger, the plasma from the source tends to survive transport through the holes and unwanted downstream charge flux will often result. In addition, undesirable discharges to these holes in conductive shields can, at times, produce an even more undesirable hollow cathode effect.
[0016] In conventional helical resonator designs, conductive external shields are interposed between the inductive power applicator (e.g., coil, etc.) and walls of the vacuum vessel containing the plasma. A variety of limitations with these external capacitive shielded plasma designs (e.g., helical resonator, inductive discharge, etc.) have been observed. In particular, the capacitively shielded design often produces plasmas that are difficult to tune and even ignite. Alternatively, the use of unshielded plasma sources (e.g., conventional quarter-wave resonator, conventional half-wave resonator, etc.) attain a substantial plasma potential from capacitive coupling to the coil, and hence are prone to create uncontrolled parasitic plasma currents to grounded surfaces. Accordingly, the use of either the shielded or the unshielded sources using conventional quarter and half-wave rf configurations produce undesirable results.
[0017] In many conventional plasma sources a means of cooling is required to maintain the plasma source and substrates being treated below a maximum temperature limit. Power dissipation in the structure causes heating and thereby increases the difficulty and expense of implementing effective cooling means. Inductive currents may also be coupled from the excitation coil into internal or capacitive shields and these currents are an additional source of undesirable power loss and heating. Conventional capacitive shielding in helical resonator discharges utilized a shield which was substantially split along the long axis of the resonator to lessen eddy current loss. However, such a shield substantially perturbs the resonator characteristics owing to unwanted capacitive coupling and current which flows from the coil to the shield. Since there are no general design equations, nor are properties currently known for resonators which are “loaded” with a shield along the axis, sources using this design must be sized and made to work by trial and error.
[0018] In inductive discharges, it is highly desirable to be able to substantially control the plasma potential relative to ground potential, independent of input power, pressure, gas composition and other variables. In many cases, it is desired to have the plasma potential be substantially at ground potential (or at least offset from ground potential by an amount insignificantly different from the floating potential or intrinsic DC plasma potential). For example, when a plasma source is utilized to generate neutral species to be transported downstream of the source for use in ashing resist on a semiconductor device substrate (a wafer or flat panel electronic display), the concentration and potential of charged plasma species in the reaction zone are desirably reduced to avoid charging damage from electron or ionic current from the plasma to the device. When there is a substantial potential difference between plasma in the source and grounded surfaces beyond the source, there is a tendency for unwanted parasitic plasma discharges to form outside of the source region.
[0019] Another undesirable effect of potential difference is the acceleration of ions toward grounded surfaces and subsequent impact of the energetic ions with surfaces. High energy ion bombardment may cause lattice damage to the device substrate being processed and may cause the chamber wall or other chamber materials to sputter and contaminate device wafers. In other plasma processing procedures, however, some ion bombardment may be necessary or desirable, as is the case particularly for anisotropic ion-induced plasma etching procedures (for a discussion of ion-enhanced plasma etching mechanisms See Flamm (Ch. 2, pp.94-183 in Plasma Etching, An Introduction, D. M. Manos and D. L. Flamm, eds., Academic Press, 1989)). Consequently, uncontrolled potential differences, such as that caused by “stray” capacitive coupling from the coil of an inductive plasma source to the plasma, are undesirable.
[0020] Referring to the above limitations, conventional plasma sources also have disadvantages when used in conventional plasma enhanced CVD techniques. These techniques commonly form a reaction of a gas composition in a plasma discharge. One conventional plasma enhanced technique relies upon ions aiding in rearranging and stabilizing the film, provided the bombardment from the plasma is not sufficiently energetic to damage the underlying substrate or the growing film. Conventional resonators and other types of inductive discharges often produce parasitic plasma currents from capacitive coupling, which often detrimentally influence film quality, e.g., an inferior film, etc. These parasitic plasma currents are often uncontrollable, and highly undesirable. These plasma sources also have disadvantages in other plasma processing techniques such as ion-assisted etching, and others. Of course, the particular disadvantage will often depend upon the application.
[0021] To clarify certain concepts used in this application, it will be convenient to introduce these definitions.
[0022] Ground (or ground potential): These terms are defined as a reference potential which is generally taken as the potential of a highly conductive shield or other highly conductive surface which surrounds the plasma source. To be a true ground shield in the sense of this definition, the RF conductance at the operating frequency is often substantially high so that potential differences generated by current within the shield are of negligible magnitude compared to potentials intentionally applied to the various structures and elements of the plasma source or substrate support assembly. However, some realizations of plasma sources do not incorporate a shield or surface with adequate electrical susceptance to meet this definition. In implementations where there is a surrounding conductive surface that is somewhat similar to a ground shield or ground plane, the ground potential is taken to be the fictitious potential which the imperfect grounded surface would have equilibrated to if it had zero high frequency impedance. In designs where there is no physical surface which is adequately configured or which does not have insufficient susceptance to act as a “ground” according to the above definition, ground potential is the potential of a fictitious surface which is equi-potential with the shield or “ground” conductor of an unbalanced transmission line connection to the plasma source at its RF feed point. In designs where the plasma source is connected to an RF generator with a balanced transmission line RF feed, “ground” potential is the average of the driven feed line potentials at the point where the feed lines are coupled to the plasma source.
[0023] Inductively Coupled Power: This term is defined as power transferred to the plasma substantially by means of a time-varying magnetic flux which is induced within the volume containing the plasma source. A time-varying magnetic flux induces an electromotive force in accord with Maxwell's equations. This electromotive force induces motion by electrons and other charged particles in the plasma and thereby imparts energy to these particles.
[0024] RF inductive power source and bias power supply: In most conventional inductive plasma source reactors, power is supplied to an inductive coupling element (the inductive coupling element is often a multi-turn coil which abuts a dielectric wall containing a gas where the plasma is ignited at low pressure) by an rf power generator. The chuck or workpiece support is often isolated from ground by a capacitance and powered by a second rf power generator which is termed a bias power supply. Rf power delivered to the chuck may cause the chuck to develop a negative DC bias voltage relative to plasma potential (for a discussion of bias, See Flamm (Ch. 1,pp.28-35, in Plasma Etching, An Introduction, D. M. Manos and D. L. Flamm, eds., Academic Press, 1989)). A bias power source is often selected to operate at the same frequency as the inductive power source, however it can also operate at a distinct frequency since the bias frequency can be adjusted to control ion bombardment energy, flux and other etching properties such as uniformity.
[0025] Vector sum voltage or current: Those skilled in the art will recognize that alternating currents and voltages are often represented as complex numbers which are sometimes termed phasors (for a explanation of phasors see Ch. 10 in Electric Circuits, 2nd Ed., by J. W. Nilsson, Addison Wesley, 1986 ISBN 0-201-12695-8. Complex voltages and currents are explained in Chapt. 8 of Electricity and Magnetism by E. M. Purcell, Berkeley Physics Course-Volume 2, McGraw-Hill, 1985, ISBN 0-07-004908-4). The vector sum of two currents I 1 and I 2 or voltages V 1 and V 2 is understood to be defined as the sum of these quantities expressed as complex numbers (phasors) which contain both magnitude and phase information. At any particular time t, actual physical current is given by the real part of this complex sum.
[0026] Inverse voltage or current: Those skilled in the art will recognize that two electrical quantities are said to be the inverse of each other when they have the same magnitude, but opposite sign. Hence if a voltage V 1 is given by V o e jωt its inverse is equal to −V o e jωt (or equivalently V o e jωt±π) . Correspondingly the vector sum of any current summed with its inverse is zero.
[0027] Inverse phase or antiphase: Two electrical quantities are defined to have an inverse phase relationship when the phase difference between them is 180° (π) or equivalently, (2n±1)π, where n is an integer number. It will be understood that two voltages or currents are in an inverse relationship when they have the same absolute magnitude and a phase difference of (2n±1)π. However the sum of a first current added to a second current characterized as having an inverse phase relation to the first (or equivalently “antiphase”) may not be zero, since the sum of these currents will balance to zero (the currents “compensate”) only when both have the same magnitude.
[0028] Conventional Helical Resonator: Conventional helical resonator can be defined as plasma applicators. These plasma applicators have been designed and operated in multiple configurations, which were described in, for example, U.S. Pat. No. 4,918,031 in the names of Flamm et al., U.S. Pat. No. 4,368,092 in the name of Steinberg et al., U.S. Pat. No. 5,304,282 in the name of Flamm, U.S. Pat. No. 5,234,529 in the name of Johnson, U.S. Pat. No. 5,431,968 in the name of Miller, and others. In these configurations, one end of the helical resonator applicator coil has been grounded to its outer shield. In one conventional configuration, a quarter wavelength helical resonator section is employed with one end of the applicator coil grounded and the other end floating (i.e., open circuited). A trimming capacitance is sometimes connected between the grounded outer shield and the coil to “fine tune” the quarter wave structure to a desired resonant frequency that is below the native resonant frequency without added capacitance. In another conventional configuration, a half-wavelength helical resonator section was employed in which both ends of the coil were grounded. The function of grounding the one or both ends of the coil was believed to be not essential, but advantageous to “stabilize the plasma operating characteristics” and “reduce the possibility of coupling stray current to nearby objects.” See U.S. Pat. No. 4,918,031.
[0029] Conventional resonators have also been constructed in other geometrical configurations. For instance, the design of helical resonators with a shield of square cross section is described in Zverev et al., IRE Transactions on Component Parts, pp. 99-110, Sept. 1961. Johnson (U.S. Pat. No. 5,234,529) teaches that one end of the cylindrical spiral coil in a conventional helical resonator may be deformed into a planar spiral above the top surface of the plasma reactor tube. U.S. Pat. No. 5,241,245 in the names of Barnes et al. teach the use of conventional helical resonators in which the spiral cylindrical coil is entirely deformed into a planar spiral arrangement with no helical coil component along the sidewalls of the plasma source (this geometry has often been referred to as a “transformer coupled plasma,” termed a TCP).
[0030] From the above it is seen that an improved technique, including a method and apparatus, for plasma processing is often desired.
SUMMARY OF THE INVENTION
[0031] The present invention provides a technique, including a method and apparatus, for fabricating a product using a plasma discharge. The present technique relies upon the control of the instantaneous plasma AC potential to selectively control a variety of plasma characteristics. These characteristics include the amount of reactive neutral species, the amount of charged species, time and spatially averaged plasma potentials, the spatial extent and distribution of plasma density, the distribution of electrical current, and others. This technique can be used in applications including chemical dry etching, ion-enhanced etching, plasma immersion ion implantation, chemical vapor deposition and material growth, and others.
[0032] In one aspect of the invention, a device is made using a process for fabricating a product. These products include a varieties of devices (e.g., semiconductor, flat panel displays, micro-machined structures, etc.) and materials, e.g., diamonds, raw materials, plastics, etc. The process includes steps of subjecting a substrate to a composition of entities. At least one of the entities emanates from a species generated by a gaseous discharge which is powered by high frequency fields coupled from an inductive coupling structure, in which the vector sum of phase and inverse-phase capacitively coupled currents between the inductive coupling structure and the gaseous plasma discharge can be selectively produced or substantially balanced. The capacitively coupled currents are driven by the AC voltage differences between the potential along the inductive coupling structure and the plasma potential. This process provides for a technique that is substantially free from stray or parasitic capacitive coupling from the plasma source to chamber bodies (e.g., substrate, walls, etc.) at or near ground potential.
[0033] In another aspect of the invention, another method for fabricating a product is provided. The process includes steps of subjecting a substrate to a composition of entities. At least one of the entities emanates from a species generated by a gaseous discharge which is powered by high frequency fields coupled from an inductive coupling structure, in which the vector sum of phase and inverse-phase capacitive coupled current from the inductive coupling structure is selectively maintained. In one embodiment of this method, a process provides for a technique that can selectively control the amount of capacitive coupling to chamber bodies at or near ground potential. In a second embodiment, the process provides for a technique that can selectively control the potential difference between the plasma and a product being processed. It will be evident to those skilled in the art that there is a relationship between the plasma potential and current. Therefore selective control of the potential difference may advantageously be used to control the amount of charge flowing to a product being processed. Merely by way of example, one such product might be a device wafer which can be damaged by excessive charge or ion bombardment energy.
[0034] In another aspect of the invention, a further method for fabricating a product is provided. The process includes steps of subjecting a substrate to a composition of entities. At least one of the entities emanates from a species generated by a gaseous discharge which is powered by high frequency fields coupled from an inductive coupling structure, in which the vector sum of phase and inverse-phase capacitive coupled current from the inductive coupling structure is selectively maintained. In one aspect of this method, a process provides for a technique that can selectively control the amount of capacitive coupling to chamber bodies at or near ground potential. In a second aspect, a process provides for a technique that can selectively control the potential difference between the plasma and a product being processed. It will be evident to those skilled in the art that there is a direct relationship between current flow to the product and the difference between plasma potential and the product potential. Therefore selective control of the potential difference may advantageously be used to control the amount of charge flowing to a product being processed. Merely by way of example, one such product might be a device wafer which can be damaged by excessive charge or ion bombardment energy.
[0035] An additional aspect of the invention, provides a further process for fabricating a product. This process includes the steps of subjecting a substrate to a composition of entities wherein at least one of the entities emanates from a species generated by a gaseous discharge. The gaseous discharge is powered by high frequency fields coupled from a coupling structure, in which the vector sum of phase and inverse-phase capacitive coupled currents from the inductive coupling structure are selectively maintained. A further step of selectively applying a voltage between the at least one of the entities in the plasma source and a substrate is provided. Yet a further step provides for sensing the current flow to a substrate and using selectively maintained voltage differences between the substrate and at least one of the entities in the plasma source to control the current flow.
[0036] Another aspect of the invention provides another process for fabricating a product. The process comprises steps of subjecting a substrate to a composition of entities and using the resulting substrate for completion of the product. At least one of the entities emanates from a species generated by a gaseous discharge provided by a plasma applicator, e.g., a helical resonator, inductive coil, transmission line, etc. This plasma applicator has an integral current flow to the plasma driven by capacitive coupling of a plasma column to elements with a selected potential greater than a surrounding shield potential substantially equal to capacitive coupling of the plasma column to substantially equal elements with a potential below shield potential.
[0037] In a further aspect, the invention provides an apparatus for fabricating a product. The apparatus has an enclosure comprising an outer surface and an inner surface. The enclosure houses a gaseous discharge. The apparatus also includes a plasma applicator (e.g., helical coil, inductive coil, transmission line, etc.) disposed adjacent to the outer surface. A high frequency power source operably coupled to the plasma applicator is included. The high frequency power source provides power to excite the gaseous discharge to provide at least one entity from a high frequency field in which the vector sum of phase and inverse-phase capacitive currents coupled from the inductive coupling structure is selectively maintained.
[0038] In another aspect, the present invention provides an improved plasma discharge apparatus. This plasma discharge apparatus includes a plasma source, a plasma applicator (e.g., inductive coil, transmission line, etc.), and other elements. This plasma applicator provides a de-coupled plasma source. A wave adjustment circuit (e.g., RLC circuit, coil, transmission line, etc.) is operably coupled to the plasma applicator structure. The wave adjustment circuit can selectively adjust phase and inverse-phase potentials between the plasma and applicator elements, produced by at least one rf power supply. The rf power supply (or supplies) are operably coupled to the wave adjustment circuit.
[0039] The present invention achieves these benefits in the context of known process technology. However, a further understanding of the nature and advantages of the present invention may be realized by reference to the latter portions of the specification and attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] [0040]FIG. 1 is a simplified diagram of a plasma etching apparatus according to the present invention;
[0041] FIGS. 2 A- 2 E are simplified configurations using wave adjustment circuits according to the present invention;
[0042] [0042]FIG. 3 is a simplified diagram of a chemical vapor deposition apparatus according to the present invention;
[0043] [0043]FIG. 4 is a simplified diagram of a stripper according to the present invention;
[0044] FIGS. 5 A- 5 C are more detailed simplified diagrams of a helical resonator according to the present invention;
[0045] [0045]FIG. 6 is a conventional quarter-wave helical resonator plasma etching apparatus with stray plasma which results from the coupling in the conventional design;
[0046] [0046]FIG. 7 is a simplified diagram of the rf voltage distribution along the coil of the FIG. 6 apparatus;
[0047] [0047]FIG. 8 is a simplified top-view diagram of an apparatus suitable for CDE or resist ashing apparatus according to the present examples; and
[0048] [0048]FIG. 9 is a simplified side-view diagram of a chamber suitable for CDE or resist ashing chamber according to the present examples.
DETAILED DESCRIPTION OF THE INVENTION
[0049] [0049]FIG. 1 is a simplified diagram of a plasma etch apparatus 10 according to the present invention. This etch apparatus is provided with an inductive applicator, e.g., inductive coil. This etch apparatus depicted, however, is merely an illustration, and should not limit the scope of the claims as defined herein. One of ordinary skilled in the art may implement the present invention with other treatment chambers and the like.
[0050] The etch apparatus includes a chamber 12 , a feed source 14 , an exhaust 16 , a pedestal 18 , an inductive applicator 20 , a radio frequency (rf) power source 22 to the inductive applicator 20 , wave adjustment circuits 24 , 29 (WACs), a radio frequency power source 35 to the pedestal 18 , a controller 36 , and other elements. Optionally, the etch apparatus includes a gas distributor 17 .
[0051] The chamber 12 can be any suitable chamber capable of housing a product 28 , such as a wafer to be etched, and for providing a plasma discharge therein. The chamber can be a domed chamber for providing a uniform plasma distribution over the product 28 to be etched, but the chamber also can be configured in other shapes or geometries, e.g., flat ceiling, truncated pyramid, cylindrical, rectangular, etc. Depending upon the application, the chamber is selected to produce a uniform entity density over the pedestal 18 , providing a high density of entities (i.e., etchant species) for etching uniformity.
[0052] The present chamber includes a dome 25 having an interior surface 26 made of quartz or other suitable materials. The exterior surface of the chamber is typically a dielectric material such as a ceramic or the like. Chamber 12 also includes a process kit with a focus ring 32 , a cover (not shown), and other elements. Preferably, the plasma discharge is derived from the inductively coupled plasma source that is a de-coupled plasma source (DPS) or a helical resonator, although other sources can be employed.
[0053] The de-coupled source originates from rf power derived from the inductive applicator 20 . Inductively coupled power is derived from the power source 22 . The rf signal frequencies ranging from 800 KHz to 80 MHz can be provided to the inductive applicator 20 . Preferably, the rf signal frequencies range from 5 MHz to 60 MHz. The inductive applicator (e.g., coil, antenna, transmission line, etc.) overlying the chamber ceiling can be made using a variety of shapes and ranges of shapes. For example, the inductive applicator can be a single integral conductive film, a transmission line, or multiple coil windings. The shape of the inductive applicator and its location relative to the chamber are selected to provide a plasma overlying the pedestal to improve etch uniformity.
[0054] The plasma discharge (or plasma source) is derived from the inductive applicator 20 operating at selected phase 23 and inverse-phase 27 potentials (i.e., voltages) that substantially cancel each other. The controller 36 is operably coupled to the wave adjustment circuits 24 , 29 . In one embodiment, wave adjustment circuits 24 , 29 provide an inductive applicator operating at full-wave multiples 21 . This embodiment of full-wave multiple operation provides for balanced capacitive coupling to of the plasma to phase 23 and inverse-phase voltages 27 along the inductive applicator (or coil adjacent to the plasma). This full-wave multiple operation reduces or substantially eliminates the amount of capacitively coupled power from the plasma source to chamber bodies (e.g., pedestal, walls, wafer, etc.) at or close to ground potential. Alternatively, the wave adjustment circuits 24 , 29 provide an inductive applicator that is effectively made shorter or longer than a full-wave length multiple by a selected amount, thereby operating with coupling to selected phase and inverse-phase voltages which do not comprise full-wave multiples. Alternatively, more than two, one or even no wave adjustment circuits can be provided in other embodiments. But in all of these above embodiments, the coupling to phase and inverse-phase potentials substantially cancel each other, thereby providing substantially no capacitively coupled power from the plasma source to the chamber bodies.
[0055] In alternative embodiments, the wave adjustment circuit can be configured to provide selected phase and inverse-phase voltages coupled from the inductive applicator to the plasma that do not cancel. This provides a controlled potential between the plasma and the chamber bodies, e.g., the substrate, grounded surfaces, walls, etc. In one embodiment, the wave adjustment circuits can be used to selectively reduce current (i.e., capacitively coupled current) to the plasma. This can occur when certain high potential difference regions of the inductive applicator to the plasma are positioned (or kept) away from the plasma region (or inductor-containing-the-plasma region) by making them go into the wafer adjustment circuit assemblies, which are typically configured outside of the plasma region. In this embodiment, capacitive current is reduced and a selected degree of symmetry between the phase and inverse-phase of the coupled voltages is maintained, thereby providing a selected potential or even substantially ground potential. In other embodiments, the wave adjustment circuits can be used to selectively increase current (i.e., capacitively coupled current) to the plasma.
[0056] As shown, the wave adjustment circuits are attached (e.g., connected, coupled, etc.) to ends of the inductive applicator. Alternatively, each of these wave adjustment circuits can be attached at an intermediate position away from the inductive application ends. Accordingly, upper and lower tap positions for respective wave adjustment circuits can be adjustable. But both the inductive applicator portions below and above each tap position are active. That is, they both can interact with the plasma discharge.
[0057] A sensing apparatus can be used to sense plasma voltage and use automatic tuning of the wave adjustment circuits and any rf matching circuit between the rf generator and the plasma treatment chamber. This sensing apparatus can maintain the average AC potential at zero or a selected value relative to ground or any other reference value. This wave adjustment circuit provides for a selected potential difference between the plasma source and chamber bodies. These chamber bodies may be at a ground potential or a potential supplied by another bias supply, e.g., See FIG. 1 reference numeral 35 . Examples of wave adjustment circuits are described by way of the Figs. below.
[0058] For instance, FIGS. 2A to 2 E are simplified configurations using the wave adjustment circuits according to the present invention. These simplified configurations should not limit the scope of the claims herein. In an embodiment, these wave adjustment circuits employ substantially equal circuit elements (e.g., inductors, capacitors, transmission line sections, and others) such that the electrical length of the wave adjustment circuits in series with the inductive applicator coupling power to the plasma is substantially an integral multiple of one wavelength. In other embodiments, the circuit elements provide for inductive applicators at other wavelength multiples, e.g., one-sixteenth-wave, one-eighth-wave, quarter-wave, half-wave, three-quarter wave, etc. In these embodiments (e.g., full-wave multiple, half-wave, quarter-wave, etc.), the phase and inverse-phase relationship between the potentials coupled to the plasma substantially cancel each other. In further embodiments, the wave adjustment circuits employ circuit elements that provide plasma applicators with phase and inverse-phase potential relationships that do not cancel each other out using a variety of wave length portions.
[0059] [0059]FIG. 2A is a simplified illustration of an embodiment 50 using wave adjustment circuits according to the present invention. This embodiment 50 includes a discharge tube 52 , an inductive applicator 55 , an exterior shield 54 , an upper wave adjustment circuit 57 , a lower wave adjustment circuit 59 , an rf power supply 61 , and other elements. The upper wave adjustment circuit 57 is a helical coil transmission line portion 69 , outside of the plasma source region 60 . Lower wave adjustment circuit 59 also is a helical coil transmission line portion 67 outside of the plasma source region 60 . The power supply 61 is attached 65 to this lower helical coil portion 67 , and is grounded 63 . Each of the wave adjustment circuits also are shielded 66 , 68 .
[0060] In this embodiment, the wave adjustment circuits are adjusted to provide substantially zero AC voltage at one point on the inductive coil (refer to point 00 in FIG. 2A). This embodiment also provides substantially equal phase 70 and inverse-phase 71 voltage distributions in directions about this point (refer to 00 -A and 00 -C in FIG. 2A) and provides substantially equal capacitance coupling to the plasma from physical inductor elements ( 00 -C) and ( 00 -A), carrying the phase and inverse-phase potentials. Voltage distributions 00 -A and 00 -C are combined with C-D and A-B (shown by the phantom lines) would substantially comprise a full-wave voltage distribution in this embodiment where the desired configuration is a selected phase/inverse-phase portion of a full-wave inductor (or helical resonator) surrounding the plasma source discharge tube.
[0061] In this embodiment, it is desirable to reduce or minimize capacitive coupling current from the inductive element to the plasma discharge in the plasma source. Since the capacitive current increases monotonically with the magnitude of the difference of peak phase and inverse-phase voltages, which occur at points A and C in FIG. 2A, this coupling can be lessened by reducing this voltage difference. In FIG. 2A, for example, it is achieved by way of two wave adjustment circuits 57 , 59 . Coil 55 (or discharge source) is a helical resonator and the wave adjustment circuits 57 , 59 are helical resonators.
[0062] The discharge source helical resonator 53 can be constructed using conventional design formulae. Generally, this helical resonator includes an electrical length which is a selected phase portion “x” (A to 00 to C) of a full-wave helical resonator. The helical resonator wave adjustment circuits are each selected to comprise a portion (2n-x) of full-wave helical resonators. Physical parameters for the wave adjustment helical resonators can be selected to realize practical physical dimensions and appropriate Q, Z 0 , etc. values. In particular, some or even all of the transmission line parameters (Q, Z 0 , etc.) of the wave adjustment circuit sections may be selected to be substantially the same as the transmission line parameters of the inductive applicator. The portion of the inductive plasma applicator helical resonator, on the other hand, is designed and sized to provide selected uniformity values over substrate dimensions within an economical equipment size and reduced Q.
[0063] The wave adjustment circuit provides for external rf power coupling, which can be used to control and match power to the plasma source, as compared to conventional techniques used in helical resonators and the like. In particular, conventional techniques often match to, couple power to, or match to the impedance of the power supply to the helical resonator by varying a tap position along the coil above the grounded position, or selecting a fixed tap position relative to a grounded coil end and matching to the impedance at this position using a conventional matching network, e.g., LC networks network, etc. Varying this tap position along the coil within a plasma source is often cumbersome and generally imposes difficult mechanical design problems. Using the fixed tap and external matching network also is cumbersome and can cause unanticipated changes in the discharge Q, and therefore influences its operating mode and stability. In the present embodiments, the wave adjustment circuits can be positioned outside of the plasma source (or constrained in space containing the inductive coil, e.g., See FIG. 2A. Accordingly, the mechanical design (e.g., means for varying tap position, change in the effective rf power coupling point by electrical means, etc.) of the tap position are simplified relative to those conventional techniques.
[0064] In the present embodiment, rf power is fed into the lower wave adjustment circuit 59 . Alternatively, rf power can be fed into the upper wave adjustment circuit (not shown). The rf power also can be coupled directly into the inductive plasma coupling applicator (e.g., coil, etc.) in the wave adjustment circuit design, as illustrated by FIG. 2B. Alternatively, other application will use a single wave adjustment circuit, as illustrated by FIG. 2C. Power can be coupled into this wave adjustment circuit or by conventional techniques such as a tap in the coil phase. In some embodiments, this tap in the coil phase is positioned above the grounded end. An external impedance matching network may then be operably coupled to the power for satisfactory power transfer efficiency from, for example, a conventional coaxial cable to impedances (current to voltage rations) existing between the wave adjustment circuit terminated end of the applicator.
[0065] A further embodiment using multiple inductive plasma applicators also is provided, as shown in FIG. 2D. This embodiment includes multiple plasma applicators (PA 1 , PA 2 . . . Pan). These plasma applicators respectively provide selected combinations of inductively coupled power and capacitively coupled power from respective voltage potentials (V 1 , V 2 . . . Vn). Each of these plasma applicators derives power from its power source (PS 1 , PS 2 . . . PSn) either directly through an appropriate matching or coupling network or by coupling to a wave adjustment circuit as described. Alternatively, a single power supply using power splitters and impedance matching networks can be coupled to each (or more than two) of the plasma applicators. Alternatively, more than one power supply can be used where at least one power supply is shared among more than one plasma applicator. Each power source is coupled to its respective wave adjustment circuits (WAC 1 , WAC 2 . . . WACn).
[0066] Generally, each plasma applicator has an upper wave adjustment circuit (e.g., WAC 1 a, WAC 2 a . . . WAC na) and a lower wave adjustment circuit (e.g., WAC 1 b, WAC 2 b . . . WACnb). The combination of upper and lower wave adjustment circuits are used to adjust the plasma source potential for each plasma source zone. Alternatively, a single wave adjustment circuit can be used for each plasma applicator. Each wave adjustment circuit can provide substantially the same impedance characteristics, or substantially distinct impedance characteristics. Of course, the particular configuration used will depend upon the application.
[0067] For instance, multiple plasma applicators can be used to employ distinct excitation frequencies for selected zones in a variety of applications. These applications include film deposition using plasma enhanced chemical deposition, etching by way of ion enhanced etching or chemical dry etching and others. Plasma cleaning also can be performed by way of the multiple plasma applicators. Specifically, at least one of the plasma applicators will define a cleaning plasma used for cleaning purposes. In one embodiment, this cleaning plasma can have an oxygen containing species. This cleaning plasma is defined by using an oxygen discharge, which is sustained by microwave power to a cavity or resonant microwave chamber abutting or surrounding a conventional dielectric vessel. Of course, a variety of other processes also can be performed by way of this multiple plasma applicator embodiment.
[0068] This present application using multiple plasma applicators can provide a multi-zone (or multi-chamber) plasma source without the use of conventional mechanical separation means (e.g., baffles, separate process chambers, etc.). Alternatively, the degree of interaction between adjacent zones or chambers can be relaxed owing to the use of voltage potential control via wave adjustment circuits. This plasma source provides for multiple plasma source chambers, each with its own control via its own plasma applicator. Accordingly, each plasma applicator provides a physical zone region (i.e., plasma source) with selected plasma characteristics (e.g., capacitively coupled current, inductively coupled current, etc.). These zones can be used alone or can be combined with other zones. Of course, the particular configuration will depend upon the application.
[0069] In the present embodiments, the wave adjustment circuit can be made from any suitable combination of element(s) such as various types of transmission lines, circuits, etc. These transmission lines include conventional solid or air dielectric coaxial cable, or ordinary, repeating inductor/capacitor discrete approximations to transmission lines, and others. These types of transmission lines are coaxial transmission lines, balanced parallel transmission lines, so called slow wave transmission lines with a spiral inner conductor (e.g., selected portions of a helical resonator, etc.), and others. Individual lumped, fixed, or adjustable combinations of resistors, capacitors, and inductors (e.g., matching networks, etc.) also can be used in place of transmission line sections for the wave adjustment circuit. These general types of wave adjustment circuits are frequency dependent, and can be termed frequency dependent wave adjustment circuits (or FDWACs).
[0070] Frequency independent elements also can be used as the wave adjustment circuits. These wave adjustment circuits can be termed frequency independent WACs (or FIWACs). Frequency independent wave adjustment circuits include degenerate cases such as short-circuit connections to ground or an infinite impedance (i.e., open circuit), and others. Frequency independent wave adjustment circuits can be used alone, or in combination with the frequency dependent wave adjustment circuits. Alternatively, the frequency dependent wave adjustment circuits can be used alone or in combination with other wave adjustment circuits. Other variations, alternative constructions, and modifications also may be possible depending upon the application.
[0071] With regard to operation of the wave adjustment circuits, various embodiments can be used, as illustrated by FIG. 2E. The wave adjustment circuits are used to select a wave length portion to be applied in the plasma applicator. In some embodiments, the average rf plasma potential is maintained close to ground potential by providing substantially equal phase 90 , 81 and inverse-phase 91 , 82 capacitively coupled portions of the inductive applicator. This can occur in multi-wave embodiments 92 , full-wave embodiments 93 , half-wave multiple embodiments, quarter-wave multiple embodiments, or any other embodiments 94 .
[0072] In alternative embodiments, it is desirable to maintain an elevated source plasma voltage relative to ground potential to induce a controlled ion plasma flux (or ion bombardment) to the product substrate (or any other chamber bodies). These embodiments are provided by selecting distinct electrical lengths for each of the wave adjustment circuit sections such that the capacitive coupled current from a phase section of the inductive plasma applicator is in excess of capacitive coupled current from its inverse-phase portion. In these embodiments, the wave adjustment circuit provides a deliberate imbalance between coupling to phase and inverse-phase voltages. In some embodiments 97 , this occurs by shifting the zero voltage nodes along the process chamber axially, thereby achieving a bias relative to the plasma discharge. As shown, the phase 95 is imbalanced relative to its inverse-phase 96 . In other embodiments 99 , one phase portion 84 is imbalanced by way of a different period relative to its complementary phase portion 85 . Other embodiments are provided where the source plasma voltage is lower relative to ground potential. In the embodiments were imbalance is desirable, the potential difference between the phase and inverse-phase potential portions is reduced (or minimized) when the amount of sputtering (e.g., wall sputtering, etc.) is reduced. The amount of sputtering, however, can be increased (or maximized) by increasing the potential difference between the phase and inverse-phase potential portions. Sputtering is desirable in, for example, sputtering a quartz target, cleaning applications, and others. Of course, the type of operation used will depend upon the application..
[0073] Current maxima on an inductive applicator with distributed capacitance (e.g., helical resonator transmission line, etc.) occur at voltage minima. In particular, conventional quarter-wave helical resonator current is substantially at a relative maximum at its grounded end of the coil, and to a lesser extend in the nearby coil elements. Therefore, partial inductive coupling of power, if it occurs, will tend to be at this grounded end. In conventional half-wave helical resonators, inductive coupling tends to occur at each of the two grounded ends.
[0074] In the present invention, substantially equal coupling to voltage elements and inverse-voltage elements along half-wave and other fractional wave inductive applicator structure sections support substantially more inductive coupling at a selected rf voltage node, e.g., FIG. 2A reference numeral 00 . This effect is caused by high current flow in the inductor applicator zones (or sections) both directly above and below the node (corresponding to inductor elements in the phase and inverse-phase sections at and immediately adjacent to the rf voltage zero point). It should be noted that conventional quarter and half-wave inductively coupled inductive applicators have inductive coupling which abruptly declines below the grounded coil locations because the coil terminates and voltage extrema are present at these locations. This generally produces conventional quarter and half-wave helical resonators that tend to operate in a capacitive mode, or with a substantial fraction of power which is capacitively coupled to the plasma, unless the plasma is shielded from coil voltages, as noted above.
[0075] In a specific embodiment, the power system includes selected circuit elements for effective operation. The power system includes an rf power source. This rf power source can be any suitable rf generator capable of providing a selected or continuously variable frequency in a range from about 800 kHz to about 80 MHz. Many generators are useful. Preferably, generators capable of operating into short and open-circuit loads without damage are used for industrial applications. One example of a suitable generator is a fixed frequency rf generator 28.12 MHz-3 kW CX-3000 power supply made by Comdel, Inc. of Beverly, Mass. A suitable variable frequency power supply arrangement capable of the 3 kW output over an 800 kHz to 50 MHz range can be made by driving an IFI Model TCCX3500 High Power Wide Band Amplifier with a Hewlett Packard HP116A, 0-50 Mhz Pulse/Function Generator. Other generators including those capable of higher or lower power also can be used depending upon the application.
[0076] Power from the generator can be transmitted to the plasma source by conventional coaxial cable transmission line. An example of this transmission line is RG8/U and other higher temperature rated cable (e.g., RG1151U, etc.) with a coaxial TEFLON™ dielectric. In some embodiments, power is fed to conventional end-grounded half-wave helical resonators by positioning a movable tap on the helical coil and connecting a power source between the tap and the ground. In other embodiments, matching networks can be introduced between the coaxial cable power feed and the, helical coil tap for flexibility. The matching network will depend on the selected wave configuration and wave adjustment circuits. In a balanced half-wave helical resonator embodiment, for example, the ends of the resonator coil can be terminated with wave adjustment circuits which substantially have zero susceptance. In particular, the wave adjustment circuit is designed as an open circuit by making no electrical connections to the ends of the coil, or establishing an electrical equivalence thereof. Alternatively, the ends of the coil are isolated by high series impedance chokes, thereby maintaining DC coupling to a fixed reference potential. These types of wave adjustment circuits are frequency independent and are “degenerate” cases. In these embodiments, the rf power is provided such that the phase and inverse-phase current flows above and below the electrical midpoint (i.e., zero voltage node, etc.) of the coil. This provides for substantially balanced phase and inverse-phase current flow from the power source stabilizing desired operation in coil voltages above the midpoint of the coil, and also provides substantially equal phase and inverse-phase voltages.
[0077] The embodiments described above also can be applied to other plasma processing applications, e.g., PECVD, plasma immersion ion implantation (PIII), stripping, sputtering, etc. For instance, FIG. 3 is a simplified CVD apparatus 100 according to the present invention. The present CVD apparatus includes a chamber 112 , a feed source 114 , an exhaust 116 , a pedestal 118 , a power source 122 , a ground 124 , a helical resonator 126 , and other elements. The helical resonator 126 has a coil 132 , an outer shield 133 , and other elements. The chamber can be any suitable chamber capable of housing a product 119 such as a wafer for deposition, and for providing a plasma discharge therein. Preferably, the chamber is a right circular cylinder chamber for providing an uniform plasma species distribution over the product. But the chamber can also be configured in the form of rectangular right cylinder, a truncated cone, and the like. The chamber and fixtures are constructed from aluminum and quartz, and other suitable materials. The plasma discharge is derived from a plasma source which is preferably a helical resonator discharge or other inductive discharge using a wave adjustment circuit or other techniques to selectively adjust phase/inverse-phase potentials. The present CVD apparatus provides for deposition of a dielectric material, e.g., silicon dioxide or the like.
[0078] The product 119 having an upper surface 130 is placed into the present CVD apparatus for deposition, e.g., plasma enhanced chemical vapor deposition (PECVD), and others. Examples of deposition materials include a dielectric material such as a silicon dioxide (SiO 2 ), a phosphosilicate glass (PSG), a borophosphosilicate glass (BPSG), a silicon nitride (Si 3 N 4 ), among others.
[0079] In one embodiment, the deposition occurs by introducing a mixture comprising organic silane, oxygen, and an inert gas such as helium or argon according to the present invention. The organic silane can be any suitable organic silicate material such TEOS, HMDS, OMCTS, and the like. Deposition is also conformal in selected instances. As for the oxygen, it includes a flow rate of about 1 liter/per minute and less. A relative flow rate between the organic silane such as TEOS and oxygen ranges from about 1:40 to about 2:1, and is preferably less than about 1:2 in certain applications. A deposition temperature of the organic silane-oxygen layer ranges from about 300 to about 500° C., and can also be at other temperatures. Pressures in the range of 1 to 7 Torr are generally used. Of course, other concentrations, temperatures, materials, and flow rates can be used depending upon the particular application.
[0080] This chamber also includes a wave adjustment circuit 127 . The wave adjustment circuit 127 is used to provide a helical coil operating with capacitive coupling to selected phase and inverse-phase voltages. This portion 127 of the wave adjustment circuit coil also is shielded 140 to prevent rf from interfering with the plasma discharge or external elements, e.g., equipment, power, etc. The coil shield 140 is made of a conductive material such as copper, aluminum, or the like. In one embodiment, an operating frequency is selected and the wave adjustment circuit is adjusted to short circuit the upper end of the helical applicator coil to ground 124 . This provides a helical coil operating at approximately a full-wave multiple and has substantially equal phase and inverse-phase sections. This full-wave multiple operation provides for balanced capacitance of phase 151 and antiphase 153 voltages along the coil 132 adjacent to the plasma source. Full-wave multiple operation reduces or even substantially eliminates the amount of capacitively coupled power from the plasma source to chamber bodies (e.g., pedestal, walls, wafer, etc.) at or close to ground potential.
[0081] In the present embodiment, the wave adjustment circuit 127 is a variable coil portion 128 of a spiral transmission line, which is selectively placed outside the outer shield 133 . Accordingly, when the wave adjustment circuit is adjusted to become a short circuit, the plasma source “sees” only a selected full-wave multiple comprising substantially equal phase 151 and anti-phase 153 of the entire instantaneous AC voltages 134 , 135 . In this embodiment, stress of the deposited oxide film is often tensile, which can be undesirable.
[0082] Alternatively, the wave adjustment circuit 127 provides a helical resonator operating at selected phase and anti-phase voltages that are not full-wave multiples. This wave adjustment circuit provides for a selected amount of capacitive coupling from the plasma source to the chamber bodies. Stress of the deposited oxide film in this embodiment can be made to be zero or slightly compressive. In some embodiments, the oxide films can be deposed with an rf plasma potential of several hundred volts between the plasma source and the substrate to decrease the tendency of the oxide film to absorb moisture. This can occur by adjusting the wave adjustment circuit to add in a small section of transmission line outside of the source and correspondingly shortening the applicator coil (by moving the lower point at which the applicator coil is short-circuited and thereby decreasing the inductance of the applicator coil and electrical length of the helical resonator 126 (e.g., spiral transmission line, etc.)). Of course, the selected amount of capacitive coupling will depend upon the application.
[0083] [0083]FIG. 4 is a simplified diagram of a resist stripper according to the present invention. The present stripping apparatus includes similar elements as the previous described CVD apparatus. The present stripping apparatus includes a chamber 112 , a feed source 114 , an exhaust 116 , a pedestal 118 , an rf power source 122 , a ground 124 , a helical resonator 126 , and other elements. The helical resonator 126 includes a coil 132 , an outer shield 133 , a wave adjustment circuit 400 , and other elements. The chamber can be any suitable chamber capable of housing a product 119 such as a photoresist coated wafer for stripping, and for providing a plasma discharge therein. The plasma discharge is derived from a plasma source, which is preferably a helical resonator discharge or other inductive discharge using a wave adjustment circuit or other techniques to selectively adjust phase/anti-phase potentials. The present stripping apparatus provides for stripping or ashing photoresist, e.g., implant hardened, etc. Further examples of such a stripping apparatus are described in the experiments section below.
[0084] In this embodiment, the wave adjustment circuits rely upon open circuits (i.e., zero susceptance). Power transfer can be effected with a balanced feed such as an inductively-coupled push-pull arrangement with means such as coupled inductors. Techniques for constructing these coupled inductors are described in, for example, “The ARRL Antenna Book,” R. D. Straw, Editor, The American Radio Relay League, Newington, Conn. (1994) and “The Radio Handbook,” W. I. Orr, Editor, Engineering Ltd, Ind. (1962), which are both hereby incorporated by reference for all purposes. In one embodiment, a ferrite or powdered iron core “balun” (balanced-unbalanced) toroidal transformer (i.e., broadband transmission transformer, broadband transformer, etc.) 401 can be used to provide balanced matching from a conventional unbalanced coaxial transmission line. Techniques for constructing toroidal baluns are described in, for example, “Transmission Line Transformers,” J. Sevick, 2nd Edition, American Radio Relay League, Newington, Conn. (1990). The toroidal transformer is coupled between the rf power source 122 and the coil 132 . The midpoint 406 between the phase 405 and anti-phase voltage on the coil is effectively rf grounded, hence it may be convenient to directly ground this midpoint of the inductive application in some embodiments for stability. This permits alternate operation in which power may be coupled into the inductive applicator (e.g., coil, etc.) with a conventional unbalanced feed line tapped on one side of the center. Push-pull balanced coupling ignites the plasma more easily than conventional unbalanced coil tap matching and generally is easier to adjust in selected applications.
[0085] Referring to the helical resonator embodiments operating at substantially equal phase and anti-phase potentials, FIG. 5A is a simplified diagram 200 of an equivalent circuit diagram of some of them. The diagram is merely an illustration and should not limit the scope of the claims herein. The equivalent circuit diagram includes a plurality of rf power supplies (V 1 , V 2 , V 3 . . . V n ) 203 , representing for example, a single rf power source. These power supplies are connected in parallel to each other. One end of the power supply is operably coupled to a ground connection 201 . The other end of the power supplies can be represented as being connected to a respective capacitor (C 1 , C 2 , C 3 . . . C n ). Each of these capacitors are connected in parallel to each other. During this mode of operation, no significant voltage difference exists between any of the common side of the capacitors, as they are all connected to each other in parallel.
[0086] [0086]FIG. 5B is a simplified diagram of instantaneous AC voltage and current along a helical resonator coil of FIG. 5A where each end of the inductive applicator is short circuited. The diagram is merely an illustration and should not limit the scope of the claims herein. This diagram includes the discharge tube 213 and an inductive plasma discharge (or plasma source) 501 therein. As shown, the plasma discharge includes an intensified “donut-shaped” glow region 501 that occupies a limited range (R) of the discharge tube 213 . The plasma discharge has an average voltage potential (Vave) of magnitude that is substantially within a few zero volts (i.e., the ground potential). As can be seen, the plasma discharge 501 has capacitively coupling elements to V H and V G . But the average voltage potential of this plasma discharge is substantially zero. This operation provides for balanced capacitance of phase 503 and anti-phase 505 voltages along the coil adjacent to the plasma, thereby substantially preventing capacitively coupling from the plasma source to chamber bodies. As also shown, a current maxima 507 exists at Vave, which corresponds to an inflection point between the phase 503 and the anti-phase 505 .
[0087] In an alternative operating mode, dim rings of plasma caused by inductively coupled plasma current are visible near top and bottom extremes of the inductive application, as illustrated by FIG. 5C. This operating mode is generally for a full-wave 517 inductive coupling coil with a voltage distribution 518 and current distribution 519 operated at a very high power, e.g., maximum power input to the inductive applicator is often limited by thermal considerations and breakdown. A full wave helical resonator applicator 523 and rf feed 524 are shown in phantom along the outside of a dielectric tube 532 enclosing the plasma. The rings 513 , 515 of current in the plasma discharge are simulated by maximum coil current areas corresponding to voltage minima at the center of the coil as well as the top and bottom shorted ends of the coil. Under high power conditions, these subordinate current rings are detectable and some excitation is often visible in the intermediate regions. This excitation is partially caused by capacitively driven currents within the discharge coupled to the voltage maximum and voltage minimum positions along the inductive applicator.
[0088] Alternatively, subordinate inductive plasma current rings at the top and bottom ends 513 of the resonator do not appear with limited input power. The coil current and inductive flux fall beyond the ends of the inductive applicator so that a single inductive ring 515 in the center portion is more stable, provided that the conductivity of the plasma is large enough to support a single current ring at a specified input power.
[0089] In alternative applications using high power operation, no secondary plasma current rings may be desirable. These applications often have substantially minimum internal capacitive coupling. In these applications, the inductive applicator (e.g., coil) abutting the vacuum vessel may be shortened from a full wave to an appropriate length such that only the central current maxima exists on the coil abutting the plasma source and the potential difference between maximum and minimum voltage on the applicator is substantially reduced. The present application is achieved by stabilizing the desired waveform along the applicator by appropriate impedance wave adjustment circuits.
[0090] Referring to the above embodiments, the present invention provides for processing with an inductively coupled plasma in which the plasma potential from coupling to a phase portion of the inductive applicator is substantially not offset by capacitive coupling to complementary anti-phase voltages on selective portions of the inductive coupling element. Conventional inductive sources (e.g., conventional helical resonators, etc.), however, have hitherto been operated in quarter-wave or half-wave modes. These modes substantially provide only phase capacitive coupling to the plasma, which raises the plasma potential toward the coil in the absence of substantial anti-phase compensation. Conventional inductive sources that are longer than a half-wave have been generally considered cumbersome and impractical for plasma reactors. In particular, these inductive sources are large in size, and have voltage nodes along the helical coil, which have been believed to create a non-uniform plasma. In order to operate a substantially inductive plasma in a helical resonator, conventional inductive sources relied upon shielding the plasma tube from electrical fields originating on the coil. Shielding occurred, for example, by inserting a longitudinally split shield between the coil and plasma tube.
[0091] The present invention provides for a substantially pure inductively coupled power source. A benefit of this inductively coupled power as a primary means to sustain plasma excitation is that electric field lines produced by inductive coupling are purely rotational (e.g. they close on themselves). Hence they do not create or support a scalar potential field (e.g. a voltage difference) within the plasma volume. Thus, in an ideal case, inductively coupled power can be transferred into a plasma without no direct relationship between the plasma potential and the voltages on coupling elements (e.g. the voltage on the coil in a helical resonator) or voltages on rf matching networks, if such are used. Furthermore, when transferring power to the plasma by purely inductive means, power transfer does not require any significant potential difference to be maintained between elements of the plasma and ground potential (e.g. the potential difference between the plasma and ground can be fixed by factors which are substantially independent of inductive excitation power). Although in theory, inductive power transfer does not require raising the AC or DC potential of the plasma with respect to ground, in practice there has been substantial potential shifts and harmful alteration in the plasma potential found in unshielded current art inductive sources.
[0092] As previously noted, and further emphasized herein, the most effective conventional method employed to avoid plasma potential shift in conventional commercially available inductive sources is to shield the plasma from the electrical fields on the inductive coupling element (commonly a multi-turn coil) by inserting a grounded conductive member between the inductive driving element and the plasma discharge tube. Shielding is, however, cumbersome and inconvenient and has serious disadvantages in practice. Shields couple to inductive applicator elements and can cause wide excursions in the natural resonance frequency, which are not predicted by conventional analytical design formulae. This often results in laborious trail and error and iterative mechanical designs to achieve a desired resonance. Another disadvantage of shielding is that shields often make it difficult to achieve initial ignition of the plasma since shields generally exclude capacitive electric fields in the plasma discharge tube. In particular, ignition (known as plasma breakdown) of inductive breakdown generally begins with a capacitive electric field discharge, which is stable at lower currents and powers See, for example, J. Amorim, H. S. Maciel and J. P. Sudana, J. Vac. Sci. Technol. B9, pp. 362-365, 1991). Accordingly, shields tend to block capacitive electric fields, which induce plasma ignition.
[0093] Insertion of the shield close to high voltage RF point in a network (such as the voltage maximum points in a helical resonator or the high potential driven side of a TCP coil) also causes large displacement currents to flow through the capacitance between the shield and coil. This high potential difference is also a potential cause of damaging rf breakdown across the air gap, hence the gap may require protection by inconvenient solid or liquid dielectric insulation. The displacement current flow causes power loss and requires that higher power RF generating equipment be used to compensate for the power loss. Coupling loss in the plasma source structure is also undesirable from the standpoint of thermal control. These limitations are overcome by the present invention using the wave adjustment circuits, an inductive applicator of selected phase length, and other elements.
EXAMPLES
[0094] To prove the principle and demonstrate the operation of the present invention, a helical resonator plasma source can be used in a photoresist stripper for ashing with a pure O 2 plasma. A substantially similar configuration is useful for chemical dry etching (CDE), as exemplified by the selective removal of silicon nitride over silicon oxide layers with a plasma sustained in feed gas mixtures containing suitable mixtures of CF 4 /O 2 /N 2 . Conventional helical resonators can also be evaluated. These are merely examples, and should not limit the scope of the claims herein. One of ordinary skill in the art would easily recognize other examples, uses, variations, and modifications of the inventions defined by the claims.
[0095] I. Conventional Photoresist Stripper
[0096] In this example, a conventional quarter-wave helical resonator resist stripper 600 can be constructed with a quarter-wave helical resonator source 602 upstream of a processing chamber 604 , shown in FIG. 6. This quarter-wave helical resonator 602 included a coil 608 and other elements.
[0097] Coil 608 consisted of 5.15 turns of 0.4 inch diameter copper tubing wound with a pitch of 0.5 turns per inch with a mean radius of 6.4 inches and centered radially and vertically inside an outer copper shield 610 . Coil 608 is operably coupled to a power source 612 and operated at about 13 MHz radio frequency. A 17 inch long, 9.25 inch diameter quartz tube 606 is centered inside of the copper coil 608 . The shield 610 is 16 inches inside diameter, approximately 0.08 inches thick and 18 inches long. This shield 610 also can be connected to a ground (V G ) connection on the aluminum process chamber body (except when making the current measurements described below).
[0098] The process chamber 604 can be for a conventional resist stripper. This resist stripper included a wafer support 616 (or pedestal) and other elements. Process chamber 604 is operably coupled at an outer location 620 to ground via shield 610 . Wafer support 616 has a wafer 618 disposed thereon.
[0099] The wafer 618 is a 6-inch (250 mm)<100> type wafer with approximately 1.25 microns of spin-coated positive photoresist. This wafer can be ashed on the grounded 10 inch diameter wafer support 616 . This support can be resistivity heated and the temperature of the substrate support can be sensed with a thermocouple.
[0100] After the helical resonator plasma is ignited, visible plasma filled the quartz plasma tube under all of the conditions used for processing. In addition, a strong plasma glow can always be visible above the wafer in the downstream processing chamber which was indicative of secondary plasma discharge to the substrate support. This secondary plasma discharge cab also be accompanied by current flow from the resonator shield to the chamber of approximately 5-10 Amperes rms (and sometimes even more) which could be measured by elevating the shield on insulating blocks and monitoring the current flow through a 2 inch long 1.5 inch wide strip of copper braid which is passed through a Pearson Current probe used to monitor the current.
[0101] [0101]FIG. 7 is a simplified diagram 700 of the rf voltage distribution along the coil for the quarter-wave helical resonator of FIG. 6. This diagram includes the quartz tube 606 and a plasma discharge (or source) 701 therein. As shown, the plasma discharge includes a glow region that 701 occupies a large range (R) of the quartz tube 606 . The plasma discharge has an average voltage (V save ) between the ground potential (V G ) and the high voltage potential (V H ). As can be seen, the plasma discharge 701 has current flow through capacitively coupling elements to V H and V G and elements of elevated potential on the coil due to its average voltage potential V ave . In fact, as previously noted, the current flow from the resonator shield to the chamber is at least 5-10 Amperes rms. In high power applications, intense sparking is observed in the chamber from the capacitively coupled plasma source.
[0102] II. New Photoresist Stripper
[0103] A resist stripper apparatus in a cluster tool arrangement using a helical resonator according to the present inventions is shown in FIG. 8 with a side view diagram of one of the two chambers, 901 , shown in FIG. 9. One of ordinary skill in the art, however, will recognize that other implementations, modifications, and variations may be used. Accordingly, the experiments performed herein are not intended to limit the scope of the claims below.
[0104] The photoresist stripper apparatus is configured with multiple process chambers in a cluster tool arrangement, as illustrated by simplified top-view diagram FIG. 8 and simplified side-view diagram of one chamber 901 in FIG. 9. Two process chambers, e.g., chamber 1 901 and chamber 2 903 , are used. Chamber 1 901 is used for stripping to upper layer of implant hardened resist (crust or skin). Chamber 2 903 is used for stripping the remaining underlayer of photoresist. Alternatively, both of these chambers can be used for stripping implant hardened resist crust and stripping remaining photoresist in parallel using sequential process operations. Of course, the particular use and recipe depends upon the application. These chambers can also be made of aluminum with inserts, which are resistant to chemical attack.
[0105] The apparatus uses a microcontroller based controller to oversee process operations. This microprocessor based controller can be accessed through a control panel 921 . A suitable controller can be made using a 486 or Pentium processor in a conventional PCI bus-based personal computer. Operator access to the control recipes and process parameters can be made using a conventional LCD touch panel display.
[0106] An automatic wafer handling system 910 is also provided. The automatic wafer handling system uses standard cassettes 912 for transferring photoresist-coated wafers to and from the process chambers 901 , 903 . The automatic wafer handling system includes a robot 917 , cassette chamber 1 905 , cassette chamber 2 907 , cassette stage 1 909 , cassette stage 2 911 , and other elements. The wafer handling system 910 uses a conventional interlock system for providing the cassettes 912 from the cleanroom into the process chambers 901 , 903 . A main shuttle chamber 913 houses the robot 917 in the cluster tool arrangement. The controller oversees the automatic wafer handling system operations.
[0107] Cooling plates 915 and 910 are optionally included in the main chamber 913 housing the robot 917 . The cooling plates 915 and 910 are of conventional design, and are capable of cooling the wafer after being stripped, which often occurs at elevated temperatures. Alternatively, the cooling plates can be used to thermally adjust the wafer temperature either before, after, or even between selected process operations.
[0108] The process chambers 901 , 903 are disposed downstream from respective plasma sources 923 , 925 . Each helical resonator includes a coil 927 disposed around a quartz tube 929 . A suitable coil consists of 11.5 turns of 0.4 inch copper tubing wound with a pitch of 0.9 turns per inch with a mean radius of 9.4 inches and centered radially and vertically inside an outer copper shield 931 . The coil is operably coupled to a power source by coaxial cable 941 which is connected to a suitable matching tap point 951 on the helical coil. A 17 inch long, 9.25 inch diameter quartz tube is centered inside of the copper coil. The shield is 16 inches inside diameter, approximately 0.1 inches thick and 18 inches long. The shield is operably coupled to upper and lower portions of the coil 971 .
[0109] Although the helical resonator delivers rf power to the discharge with very high efficiency, the plasma source and applicator structures are often strongly heated by the energy released from within the plasma discharge chamber. Hence it is desirable to control the temperature of the plasma source and rf applicator structure. This is conveniently done by means of a liquid heat transfer agent (e.g. deionized water or a suitable heat exchange fluid) which is maintained at a constant temperature and circulated through the tubular helical coil by way of fluid connections 987 and 988 . Additional means for cooling the shield 931 (not shown in FIG. 9) are provided for use in certain high power applications. It will be obvious to those skilled in the art that heat transfer utilizing a gaseous coolant (e.g. air or nitrogen) or external conductive or convective heat transfer means can also be used in many applications.
[0110] Processes in this equipment may be used for stripping photoresist from wafers, e.g., See FIG. 9 reference numeral 933 , or selected CDE operations such as the selective removal of silicon nitride films which have been deposited over silicon oxide. Particular processes may involve a multi-step stripping operation to remove implanted photoresist from semiconductor wafers. For example, Photoresist 1.5 microns in thickness on device wafers may be implanted. This implant operation causes the formation of an implant hardened stratum over the top of an underlying layer of normal photoresist.
[0111] A clean implant resist stripping process can be conveniently be performed by stripping the top implant hardened resist layer by ion-assisted ashing using an “un-balanced” coupling relationship in a half-wave helical resonator. A suitable half-wave helical resonator is configured in one of the process chambers. The half wave helical resonator plasma chamber can be conveniently operated at a frequency of about 13.56 MHz corresponding to a full-wave multiple. In this chamber, the pedestal can conveniently be maintained at a low wafer temperature in the range of 50C-80C to reduce the possibility of “popping.” Popping occurs when the pressure of low molecular weight monomer, oligimer or solvent in the underlying photoresist bursts the relatively impermeable implant hardened surface layer of the resist.
[0112] After the uppermost hardened layer of the resist is removed, the wafer is transferred into a chamber operating in a suitable balanced configuration such as a full-wave multiple. Plasma confinement afforded by use of the present invention avoids damaging current flow and ion bombardment to the substrate when it as exposed as the resist is “cleared” just before and after “endpoint.” The full wave helical resonator plasma chamber can be conveniently operated at a frequency of about 27.12 MHz corresponding to a full-wave multiple. The pedestal of this chamber is generally maintained at a selected temperature in the range of 150 to 220C. It is advantageous to operate at as high a temperature as is permissible because the ashing chemical reaction rate increases with temperature and therefore the machine productivity (throughput) will be greater. However the maximum usable temperature is often limited by the vulnerability of device layers to harmful thermal effects. For example, some silicon antireflection coatings require that temperature be limited to below about 170-180C. Another limitation on temperature is related to uniformity. Temperature uniformity in some heater configurations deteriorates with increasing temperature owing to a shift from dominantly conductive and convective heat transfer to an energy balance in which radiative heat transfer processes have a greater role. In general, there are proportionately greater amounts of heating and cooling by radiation at higher temperatures, since radiative energy transfer depends on the temperatures of surfaces which “view” each other raised to the fourth power, whereas conductive and convective heat transfer often depend linearally on localized temperature differences. It is desirable that etching and ashing processes be highly uniform in order that the overetch period during which all or portions of device layers are exposed to reactive plasma species can be minimized. Plasma induced damage, if it occurs, is known to take place after some or all parts of device layers are exposed. (A discussion of damage and temperature effects in resist stripping is given in “Dry Plasma Resist Stripping” by D. L. Flamm in Solid State Technology, pps. 37-39, August 1992 (Part I),pps. 43 - 48 , September 1992 (Part II) and pps. 43-48, October 1992 (Part III)). A balanced structure which provides for substantially equal capacitive coupling to applicator elements with rf voltages inverse to each other, in particular a balanced full wave structure such as that described in this example provides for balanced phase and inverse-phase coupled currents, thereby reducing the amount of capacitively coupled plasma, which can be detrimental to the underlying substrate. In this step, overashing is performed to substantially remove all photoresist material from the wafer. No damage occurs to the underlying substrate during this overashing step.
[0113] Once the photoresist has been stripped, the wafer is cooled. In particular, the wafer is removed from the full-wave multiple process chamber, and placed on the cooling station. This cooling station reduces the temperature of the wafer (which was heated). This wafer is then reloaded back into its wafer cassette. Once all wafers have been processed in the cassette, the cassette comprising the stripped wafers is removed from the cluster tool apparatus. Characteristics of this half-wave helical resonator were described in detail above.
[0114] Useful processing conditions for ashing 6-inch wafers with normal (not ion-implanted) photoresist are pressures in the range of 0.1 to 10 Torr using a gas flow in the range of 0.1 to 10 standard liters per min. and input power to the plasma of approximately 1.5 to 2.5kW (For this purpose power is defined to be the net power transferred to the helical resonator structure, e.g. forward-reflected power in the transmission feed line, since the helical resonator is extremely efficient e.g. more than 90% of transferred power is absorbed by the plasma). Under these conditions an ashing rate above 3kÅ/min are readily achieved when ashing a lower temperature (e.g. c.a. 60C) and rates of 1 μ/min and higher can be achieved when the temperature is elevated (in the range of 170-210C). When feed the feed gas flow profile is sufficiently uniform (A wide residence time distribution of gas flow in the plasma source is undesirable. In the example the residence time is made more homogeneous by the imposition of a baffle plate 975 below the feed gas inlet 976 . Ashing uniformity in a chamber geometry exemplified by FIG. 9 is mainly determined by temperature uniformity across the wafer. When the resist asher is equipped with a suitably designed wafer heating means such as a multizone resistive heater 981 with multiple electrical connections 983 - 986 as shown in FIG. 9, an average etching uniformity better than 5% is readily achieved.
[0115] A visual inspection of wafers stripped in this type of apparatus can show extremely good results. That is, the wafers are stripped at a sufficient rate for production operation and no substantial damage occurs to the wafers. This provides for effective wafer turn-around-time and substantially no damage caused by the plasma. In addition, current measured from the shield to the chamber by elevating the shield on insulating blocks is substantially less than current(s) measured in a conventional (unbalanced) helical resonator stripping apparatus.
[0116] While the invention has been described with reference to specific embodiments, various alternatives, modifications, and equivalents may be used. In fact, the invention also can be applied to almost any type of plasma discharge apparatus. This discharge apparatus can include an apparatus for plasma immersion ion implantation or growing diamonds, TCPs, and others. This discharge apparatus can be used for the manufacture of flat panel displays, disks, integrated circuits, diamonds, semiconductor materials, bearings, raw materials, and the like. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.
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A process for fabricating a product 28, 119. The process comprises the steps of subjecting a substrate to a composition of entities, at least one of the entities emanating from a species generated by a gaseous discharge excited by a high frequency field in which the vector sum of currents to phase and inverse-phase capacitive coupled voltages from the inductive coupling structure can be selectively maintained.
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The present invention relates to a disk brake for a motor vehicle, comprising: two brake elements which can move with respect to each other, one of which is a caliper straddling a brake disk and the other of which is a carrier fixed to the vehicle; clamping means comprising a tip of the caliper, the tip consisting of a flat shaping of the caliper formed facing a first face of the disk, and a cylinder connected to the caliper and closed by a piston turned toward a second face of the disk; guide means allowing the caliper to slide with respect to the carrier under the effect of urging from the clamping means; and first and second friction pads turned respectively toward the first and second faces of the disk, clamped between the piston and the tip of the caliper and moved in an axial direction of the piston by urging from the clamping means until they are applied against the disk; each of the two pads exhibiting two substantially flat faces, the first of which is partially covered with a friction material, and two lateral lugs; the first and second lugs of the first pad interacting with first and second respective supports of the carrier; and the first pad carrying, on its second face, an elongate spring, with two main branches, which points in a tangential direction of the disk and is intended to hold the first pad on the tip of the caliper and elastically clamps the tip of the caliper between the respective free ends of its two branches and the second face of the first pad.
BACKGROUND OF THE INVENTION
Devices which comply with this definition, which encompasses a number of disk brakes, are well known in the prior art, as shown, for example, in the documents U.S. Pat. No. 4,082,166 and EP-A-0 112 255.
One of the problems posed in disk brakes, particularly those which use pads of the type identified previously, lies in the difficulty of giving the pad, particularly the so-called "outboard" pad which is distant from the piston, a predetermined and reproducible position.
This difficulty is particularly troublesome if the pad is attached to the carrier and/or assumed to bear continuously against it, poor positioning of the pad with respect to the caliper then giving rise upon braking to a transient condition which is both noisy and ineffective.
The invention falls within this context and its object is to provide a braking device which, although it is of simple structure, ensures that the outboard pad has a predetermined and reproducible position with respect to the carrier.
SUMMARY OF THE INVENTION
To this end, the brake of the invention, which in other respects complies with the preamble hereinabove, is essentially characterized in that the ends of the two main branches of the spring point toward the tip of the caliper and bear elastically against respective bearing surfaces of the tip of the caliper, in that the bearing surfaces are inclined both with respect to the axial direction of the piston and with respect to the first face of the disk, and in that the bearing surfaces exhibit opposite slopes with respect to the axial direction of the piston, so as partially to convert the elastic bearing of the free ends of the branches of the spring on the bearing surfaces into a torque urging the first pad to rotate about an axis parallel to the axial direction of the piston.
For example, the bearing surfaces may be formed by the edges of two respective V-shaped grooves cut in the tip of the caliper, and the free ends of the branches of the spring are preferably cut into a point with a rounded end.
The features of the invention are particularly useful in a brake in which the first lateral lug of the first pad at least, and the first support of the carrier, exhibit partially complementary profiles which fasten the first pad with respect to the carrier and in which the second lateral lug of the first pad at least, and the second support of the carrier, exhibit respective regions in contact with each other and ensuring that the first pad bears continuously against the carrier.
According to one possible embodiment of the invention, the lateral lugs of the first pad may be rounded.
Irrespective of the embodiment, it may be advantageous further to provide for the spring to include an additional branch bearing against the tip of the caliper in order to urge the first pad in translation.
Further features and advantages of the invention will emerge clearly from the description thereof given hereafter by way of non-limiting indication with reference to the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a disk brake in accordance with the invention;
FIG. 2 is a front view of the disk brake of FIG. 1, viewed in the direction identified by the arrows 2--2 of FIG. 1;
FIG. 3 is a view similar to that of FIG. 2, distinguishable therefrom merely in that it illustrates, in a less complete and more diagrammatic fashion, another embodiment of a disk brake in accordance with the invention;
FIG. 4 is a part section view in the direction of the arrows 4--4 of FIG. 3, and enlarged;
FIG. 5 is an enlarged view of the spring illustrated in FIG. 3; and
FIG. 6 is a part section view in the direction of the arrows 6--6 of FIG. 3, and enlarged.
DETAILED DESCRIPTION OF THE INVENTION
As shown especially in FIGS. 1 and 2, the invention relates in general to a disk brake, such a brake conventionally comprising: two brake elements which can move with respect to each other, one of which is a caliper 1 straddling a brake disk D and the other of which is a carrier 2 fixed to the vehicle; clamping means comprising a tip of a caliper 10, the tip consisting of a flat shaping of the caliper formed facing a first face Di of the disk D, and a cylinder 3 connected to the caliper 1 and closed by a piston 31 turned toward a second face D2 of the disk D; guide means, such as guide pins 11, 12, connected to the caliper and sliding in bores 21, 22 of the carrier, to allow the caliper 1 to slide with respect to the carrier 2 under the effect of urging from the clamping means; and first and second friction pads 41 and 42.
These first and second friction pads 41 and 42 are turned respectively toward the first and second faces D1 and D2 of the disk D (FIG. 1), are clamped between the piston 31 and the tip 10 of the caliper 1 and are capable of being moved in the axial direction A of the piston 31 by an increasing pressure in the cylinder 3, by virtue of which the piston 31 on the one hand and the tip 10 of the caliper 1 on the other hand apply them against the disk D.
Each pad such as 41 or 42 includes two substantially flat faces such as 411, 412 and 421, 422, the first 411, 421 of which is partially covered, in a central region, with a friction material F (FIG. 1).
Each pad further includes, on either side of this central region, two lateral lugs such as 41a and 41b, the lugs of the first pad at least interacting with the respective supports 23a, 23b of the carrier 2.
Furthermore, on its second face 412, the first pad 41 carries an elongate spring 5, with two main branches 51 and 52, which is oriented in a tangential direction of the disk D, is intended to hold the first pad 41 on the tip 10 of the caliper, and elastically clamps the tip 10 of the caliper between the respective free ends 510, 520 of its two branches and the second face 412 of this first pad.
It is important, for the invention, for the spring 5 to be secured to the second face 412 of the first pad 41 in a way which prevents any relative rotation of this spring and of this pad, and for example by means of two spaced-apart anchoring points 53, 54.
According to the invention, the ends 510, 520 of the two main branches 51, 52 of the spring 5 point toward the tip 10 of the caliper (FIGS. 4 and 6) and bear elastically against respective bearing surfaces 130, 140 of the tip 10 of the caliper.
Moreover, these bearing surfaces 130, 140 are inclined both with respect to the axial direction A of the piston and with respect to the first face D1 of the disk, and exhibit opposite slopes with respect to the axial direction A of the piston, so as partially to convert the elastic bearing of the free ends 510, 520 of the branches 51, 52 of the spring 5 on the bearing surfaces 130, 140 into a torque C--C urging the first pad 41 to rotate about an axis X parallel to the axial direction A of the piston and, in this case, coincident with the axis of the piston in FIGS. 2 and 3.
As FIGS. 4 and 6 show, the bearing surfaces 130, 140 may be formed adequately by the edges of two respective V-shaped grooves 13 and 14 cut in the tip 10 of the caliper.
Furthermore, the free ends 510, 520 of the main branches 51, 52 of the spring 5 are preferably cut into a point with a rounded end in order to be able to slide better over the bearing surfaces 130, 140.
The invention is particularly advantageous in the case, illustrated in FIGS. 2 and 3, in which the first lateral lug 41a of the first pad 41 at least, and the first support 23a of the carrier 2, exhibit partially complementary profiles which fasten the first pad 41 with respect to the carrier 2, and in which the second lateral lug 41b of the first pad 41 at least, and the second support 23b of the carrier 2, exhibit respective regions in contact with each other and ensuring that the first pad bears continuously against he carrier.
In point of fact, in such a configuration, in which the disk D is assumed to have a favoured direction of rotation indicated by the arrow R, the torque C--C which urges the first pad 41 to rotate about the axis X has the effect of reinforcing the holding of each of the two ends of this pad by the carrier.
By way of indication, and as shown in FIG. 3, the lateral lugs 41a, 41b of the first pad at least may be rounded.
Irrespective of the shape of these lugs, it may further be advantageous, as illustrated in FIGS. 2, 3 and 5, for the spring 5 to include an additional branch 55 bearing against the tip 10 of the caliper, in order to urge the first pad 41 in translation and reinforce its contacts with the carrier.
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A disk brake for a motor vehicle having a caliper (1), a carrier (2) which fixed to the vehicle and a pad (41) located between a tip (10) on the caliper (1) and a disk (D). The pad (41) being fitted with a spring (5) which holds the pad against the tip (10) of the caliper (1). The spring (5) bears elastically on inclined surfaces of the tip (10) of the caliper (1) and is subjected to a torque (C--C) which urges the spring (5) to rotate about an axis (X) and to continually urge the spring (5) against the carrier (2).
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to co-pending application Ser. No. 61/990,032 filed on Sep. 10, 2012, the contents of which are fully incorporated herein.
FIELD
[0002] The improvements generally relate to the field of oil production equipment, and more particularly relates to the operation of handling and cutting continuous rods used in oil well pumps.
BACKGROUND
[0003] During recent years, continuous rods have become more and more popular compared to traditional sucker rods to activate the pumps located at the bottom of oil wells. Typical sucker rods consisted of a long string of 20 to 30 foot steel rods (e.g. ˜200) which were assembled to one another at the well site and used to connect the pump in the well to the pump jack (horse head) located at ground level. Continuous rods consist of a single rod of the same length and can offer significantly increased durability, in addition to being usable both for progressive cavity pumping and reciprocating cavity pumping. Several forms of equipment have been developed in recent years to address the issues pertaining to handling such rods, and these include 20 feet diameter spools which are used to coil the continuous rod for transport. On site, the continuous rod is uncoiled from the spool until the desired length is reached, at which time the rod is cut. Cutting the rod typically requires over 100 000 PSI of shear stress while maintaining a firm grasp on the rod which can be spring loaded with an impressive amount of energy. Although the existing equipment was satisfactory to a certain degree, there remained room for improvement, particularly for the steps of handling and cutting such rods.
SUMMARY
[0004] In accordance with one aspect, there is provided a reversible continuous rod cutting system comprising: a base; a rod path; a shear cutting unit mounted to the base and having a cutting jaw operable to cut across the rod path; and two pinch roller units mounted to the base, each on a respective side of the cutting jaw, each having at least one corresponding pair of rollers, the rollers of each pair being aligned with the rod path, on opposite sides of the rod path, each pair of rollers being operable to move a first one of the rollers relative a second one of the rollers into and out from engagement with the rod path, and each pair of rollers being selectively operable into cooperating opposed rotation in both directions, independently of said relative movement operability, for moving a rod engaged therebetween in a corresponding direction along the rod path and stopping and holding the rod for subsequent cutting by the shear cutting unit.
[0005] In accordance with another aspect, there is provided a method of cutting a continuous rod using a system having a base, a rod path, a shear cutting unit mounted to the base and having a cutting jaw operable to cut across the rod path and two pinch roller units mounted to the base, each on a respective side of the cutting jaw, each having at least one corresponding pair of rollers, the rollers of each pair being aligned with the rod path, on opposite sides of the rod path, said method comprising: positioning the continuous rod in the rod path; moving a first one of the rollers of at least one of the pairs relative a second one of the rollers of the corresponding pair into engagement with the continuous rod; rotating the first and second engaged rollers into cooperating opposed rotation, thereby moving the continuous rod along the rod path; stopping the cooperating opposed rotation of the first and second engaged rollers when a selected portion of the continuous rod is aligned with the cutting jaw; and cutting the continuous rod using the shear cutting unit while the first and second rollers hold the selected portion of the continuous rod in alignment with the cutting jaw.
[0006] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.
DESCRIPTION OF THE FIGURES
[0007] In the figures,
[0008] FIG. 1 is an oblique view of an example of a continuous rod cutting system;
[0009] FIGS. 2 to 4 are left side, front, and rear elevation views thereof, respectively;
[0010] FIG. 5 is another oblique view, taken partially from below;
[0011] FIG. 6 is another oblique view thereof, in a deployed state;
[0012] FIG. 7 shows an example of a working configuration; and
[0013] FIG. 8 is a hydraulic schematic thereof.
DETAILED DESCRIPTION
[0014] FIG. 1 shows an example of a continuous rod cutting system 10 . The system 10 can generally be seen to include a base 12 onto which two pinch roller units 14 , 16 are mounted on corresponding sides of a shear cutting unit 18 . The pinch roller units 14 , 16 each include a corresponding pair of rollers 20 , 22 associated with a mechanism which makes them both operable to move toward and away from one another to selectively engage a continuous rod located therebetween. The rollers 28 , 30 of each pair and operable to rotate in cooperating opposite angular directions when engaged, to move the continuous rod in a selected one of two opposite directions. The illustrated example offers a high degree of versatility, and is reversible in the sense that it can receive a continuous rod from either side. Moreover, in this specific embodiment, the base is pivotally mounted on an extendible frame portion 15 in a manner to provide a high degree of versatility.
[0015] The path which the continuous rod follows as it is moved by the rollers will be referred to herein as the continuous rod path 24 , for later reference. The continuous rod path 24 crosses a cutting jaw 26 of the shear cutting unit 18 , where the continuous rod is cut at the desired length.
[0016] During operation, a continuous rod can be positioned in the continuous rod path 24 from either side and engaged by one or both pairs of rollers 20 , 22 , which are then rotatably operated to move a selected length of rod. When the selected portion of the continuous rod is aligned with the cutting jaw 26 , the pairs of rollers 20 , 22 can be stopped to hold the continuous rod into a fixed position relative the cutting jaw 26 for a period of time during which the shear cutting unit 18 is operated to cut the continuous rod at the selected portion, or desired length. The pairs of rollers 20 , 22 , each then holding a corresponding section of continuous rod material, can then independently be operated into cooperating rotation in either angular direction, or operated into relative movement to disengage a corresponding one, or both, of the continuous rod sections. This operation can be user-controlled via a control panel, remote control, smart phone application, or other appropriate interface for instance.
[0017] Each of these functions (i.e. pinch-release (2); forward-reverse cooperation rotation (2); cut-release; pivoting and extension-retraction, both of which will be detailed further below) can be hydraulically powered, for instance. An example of a system equipped with a hydraulic power unit is shown in FIG. 7 , the example hydraulic circuit of which is provided at FIG. 8 . Though the pictured prototype is made fully independent, equipped with a gas generator set, a hydraulic power pack and an electric bypass for interior use, it will be understood that alternate embodiments are possible, as will be understood by persons skilled in the art.
[0018] Turning to FIG. 2 , the details of the pinch roller units 14 , 16 will now be provided. In this particular example, both pinch roller units 14 , 16 are identical, and only one will therefore be described in detail. In this embodiment, the pinch roller units 14 , 16 each include a single pair of rollers 28 , 30 . Each roller 28 , 30 is received in a corresponding housing 32 , 34 in which it is hydraulically powered for rotation according to the schematic of FIG. 7 . The bottom housing 34 is fixed to the base 12 , whereas the upper housing 32 is pivotally mounted to the bottom housing 34 . A roller hydraulic cylinder 36 is positioned between the base 12 and a distal end 38 of the upper housing 32 , the distal end 38 being located opposite the upper roller 28 relative the pivot axis 40 . Henceforth, when the roller hydraulic cylinder 36 is activated, the upper roller 32 is moved correspondingly towards, or away from the lower roller 30 to respectively engage (pinch) or release the continuous rod. When the rollers 28 , 30 are in the engaged configuration, both their axes are oriented horizontally, perpendicular to the continuous rod path 24 which also extends horizontally. It will be understood that the above example is provided for illustrative purposes only, and that alternate embodiments can include roller housings which slide (e.g. vertically) relative to one another rather than pivot, and/or more than one pair of rollers on either side of the shear cutting unit, for example.
[0019] Turning now to FIGS. 1 and 6 , the details of the shear cutting unit 18 will now be provided. In this particular example, the cutting jaw 26 of the shear cutting unit 18 is located at the front, to receive the continuous rod path 24 , and the shear cutting unit 18 includes a first portion 42 which is made integral to the base 12 and a second portion 44 which is pivotally mounted relative the first portion, about a pivot axis 46 . The first portion 42 includes a first, fixed half 48 of the cutting jaw 26 and the second portion 44 includes a second, mobile half 50 of the cutting jaw 26 , and a lever arm 52 . A cutting hydraulic cylinder 54 fixed to the base 12 , is used to activate the cutting jaw 26 by moving the lever arm 52 . A guide 56 is also provided in this case, in the shape of a horizontally oriented “V”, to ease the task of positioning the continuous rod into the rod path 24 .
[0020] The mobile half 50 of the cutting jaw 26 is positioned at a first distance from the pivot axis 46 , whereas the lever arm 52 extends to a second distance from the pivot axis 46 . The second distance from the pivot axis 46 is significantly greater than the first distance from the pivot axis 46 , allowing to leverage force exerted onto the end of the lever arm 52 and concentrate it at the cutting jaw 26 . For the purpose of illustration, cutting a typical continuous rod can require between 130 000 and 140 000 PSI. Leveraging the force using a lever arm 52 such as illustrated can significantly reduce the costs and constraints related to the hydraulic cylinder used.
[0021] Comparing FIGS. 1 and 5 to FIGS. 3 and 4 , it will be understood how the base 12 can be pivoted relative to an extendible frame portion 15 . This pivoting feature is optional, but can be very useful in aligning the cutting rod path 24 tangentially with the large spools continuous rods are typically wrapped around. In this particular embodiment, the base 12 is made pivotal by interfacing it with the extendible frame portion via a pivoting plate 35 having an arc-shaped guide path 33 formed therein. One or more swivel hydraulic cylinders 37 can have one end mounted to the extendible frame portion 15 , and the other end mounted to the pivotal base 12 via a guide pin 39 which extends across, and is guided by, the arc-shaped guide path 33 . The pivoting mechanism shown in FIG. 5 is only an example and it will be understood that the exact pivoting mechanism used in alternate embodiments, if any, can be different than the one shown herein and described above.
[0022] Comparing FIG. 1 to FIG. 6 , the deployment of the continuous rod cutting system 10 will now be described. In this embodiment, the continuous rod cutting system 10 includes a deployment mechanism. The deployment mechanism includes a fixable frame portion 58 onto which the extendible frame portion 15 is slidably mounted by means of two lengthwisely spaced pairs of rollers 60 a, 60 b, 62 a, 62 b engaged with a corresponding rail 64 a, 64 b on each side of the continuous rod cutting system 10 . The front of the extendible frame portion 15 , which coincides with the continuous rod path 24 , can thus be slid a significant distance from the fixable frame portion 58 . Two foldable legs 66 a, 66 b are used to support the weight of the cantilevered portion during operation, and these are hinged to the front of the extendible frame portion 15 , on opposite sides, and can be folded under the extendible frame portion 15 when unused. A spacing 68 , such as best seen in FIGS. 3 and 4 , can be provided between the extendible frame portion 15 and the fixable frame portion 58 into which the folded legs 66 a, 66 b can be nested when the extendible frame portion 15 is retracted onto the fixable frame portion 58 . The sliding of the extendible frame portion 15 relative the fixable frame portion 58 can be powered via a roll out hydraulic cylinder 70 as illustrated.
[0023] It will be noted that the deployment mechanism described above is optional. It can be used to provide greater versatility and portability of the continuous rod cutting system 10 , such as by allowing its mounting to the box of a pick-up truck, for instance. Alternately, the deployment mechanism can be omitted and the base be mounted directly to a reel transport deck of a semi-truck, to name one alternate example. If the pivoting mechanism is omitted in an embodiment, the base 12 can be slidably mounted directly to the fixable frame portion 58 , for instance.
[0024] As can be seen from the above, the examples described above and illustrated are intended to be exemplary only. The scope is indicated by the appended claims.
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The continuous rod cutting system has a base; a rod path; a shear cutting unit mounted to the base and having a cutting jaw operable to cut across the rod path; and two pinch roller units mounted to the base, each on a respective side of the cutting jaw, each having at least one corresponding pair of rollers aligned with the rod path, on opposite sides of the rod path. The rollers being movable relative one another of the corresponding pair, into and out of engagement with the rod path, and each pair of rollers being selectively operable into cooperating opposed rotation in both directions, independently of said relative movement operability, for moving a rod engaged therebetween in a corresponding direction along the rod path and stopping and holding the rod for subsequent cutting by the shear cutting unit.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of DE 10 2013 210 237.2, filed on Jun. 3, 2013, which is hereby incorporated by reference in its entirety.
TECHNICAL FIELD
The embodiments relate to methods for operating a mobile magnetic resonance tomography system including magnets and/or coils generating a magnetic field and a shield surrounding the magnets and/or coils. The embodiments further relate to mobile magnetic resonance tomography systems.
BACKGROUND
Magnetic resonance tomography (MRT) enables sectional images (slices) of the human (or animal) body to be generated that permit an assessment of the organs and many pathological organ changes. MRT is based on very strong magnetic fields, generated in a magnetic resonance tomography (MRT) system, as well as on alternating magnetic fields in the radio frequency range by which specific atomic nuclei (mostly the hydrogen nuclei/protons) in the body are excited into resonance, thereby inducing an electrical signal in a receiver circuit.
MRT systems may be installed as stationary appliances. It is, however, also possible to install mobile MRT systems for example on trailers of heavy-duty motorized tractor vehicles, which may then be brought to the respective deployment location. Such mobile MRT systems require a stray magnetic field shield made of iron. Due to the constricted space conditions in trailers, the shield extends by reason of construction-related constraints two-dimensionally in the vertical walls over an area of approximately 30 m 2 and is closer to the magnets of the MRT system and less insulated from the outside world than in the case of stationary installations.
Since mobile MRT systems may be set up in the open, changing weather conditions lead to spatially and temporally widely varying amounts of heat being introduced into the iron shield. The change in temperature of the iron leads to a change in the susceptibility of the iron and consequently to a change in magnetization. This disrupts the homogeneity of the static magnetic field of the MRT system. Furthermore, the shielding iron expands as a result of its being heated, which likewise affects the homogeneity of the static magnetic field. Frequency shifts and image quality limitations during the MRT examination are the consequence.
Efforts have thus far been directed at attempting to realize a mounting of the iron shield that is largely decoupled mechanically and thermally from the trailer. Given a typical weight of several metric tons, this is problematic and only achievable with compromises. For this reason, additional heat insulation is normally provided in the external walls of the trailer to act as a thermal shield, e.g., in the form of panels made of synthetic organic foams having the lowest possible coefficient of heat transmission. In this case, however, consideration is given to the amount of space available. Therefore, the desired heat insulation is in contention with space requirements in the trailer as well as with the permissible external dimensions.
SUMMARY AND DESCRIPTION
The scope of the present invention is defined solely by the appended claims and is not affected to any degree by the statements within this summary. The present embodiments may obviate one or more of the drawbacks or limitations in the related art.
It is therefore the object of the embodiments to disclose a method for operating a mobile magnetic resonance tomography system as well as a mobile magnetic resonance tomography system that enable an optimal image quality during the examination at the same time as having a small space requirement.
With regard to the method, a temperature measurement is taken by a temperature measuring system at a plurality of points on the shield, where measured data of the temperature measuring system is sent to a compensation system, and where effects of temperature differences on the homogeneity of the magnetic field are compensated by the compensation system.
With regard to the magnetic resonance tomography system, the magnetic resonance tomography system includes a temperature measuring system having temperature measuring sensors arranged at a plurality of points on the shield, and a compensation system that is connected to the temperature measuring system on the measured data input side, where the compensation system is designed to compensate for effects of temperature differences on the homogeneity of the magnetic field.
The embodiments proceed here from the consideration that the greatest possible homogeneity of the static magnetic field in the MRT system may be provided in order to achieve an optimal image quality. In order not to restrict the free space available for the MRT system, (e.g., on the trailer of a heavy-duty tractor unit), it is not likely in this case to achieve a complete thermal and mechanical insulation of the magnetic shield from the outside world. Rather, certain temperature differences are inevitably given. In a first act to restore the homogeneity of the magnetic field disrupted by the temperature differences in the shield, a precise knowledge of the temperature distribution may therefore be acquired. For this purpose, a temperature measuring system is provided that includes a plurality, (e.g., a two-digit number), of temperature measuring sensors distributed at different points of the shield. The temperatures measured here are forwarded to a compensation system in which a temperature profile may now be generated that enables a targeted compensation of the temperature fluctuations and their effects on the homogeneity of the magnetic field.
In an advantageous embodiment of the method, the temperature differences are equalized by a plurality of heating and/or cooling elements of the compensation system. For this purpose, the compensation system advantageously includes a plurality of corresponding heating and/or cooling elements. The idea in this case is to correctively adjust the local temperature differences, the profile of which was determined in the compensation system, by corresponding heating and/or cooling elements such that a homogeneous temperature distribution is achieved over the entire shield. By this protocol, the susceptibility and expansion of the shield are balanced out and therefore inhomogeneities in the magnetic field are minimized.
In this case, the highest measured temperature is advantageously determined in the compensation system and the temperature is brought to the highest measured temperature at all points. The compensation system is advantageously designed accordingly therefor. Regulating the temperature to the highest temperature measured on the shield affords the advantage that no cooling is necessary and cooling elements may be dispensed with. Instead, comparatively lower-cost and technically easier-to-implement heating elements are used, such as, e.g., heating foils or planar heating elements.
In a second alternative or additional advantageous embodiment of the method, a number of auxiliary coils of the compensation system are energized with electric current based on the measured temperatures. For this purpose, the compensation system advantageously includes a corresponding number of auxiliary coils to which electric current may be applied by the compensation system. Instead of equalizing the temperature variations themselves, or in addition thereto, it is possible to restore the homogeneity of the magnetic field directly using corresponding auxiliary coils, which are also referred to as shim coils. Shim coils are often present already in MRT systems for the purpose of compensating, e.g., for stray fields or structural tolerances. However, the currents acting on the coils are not set in the compensation system based on a complicated measurement of the magnetic field itself, but in this case use is specifically made of the fact that the spatial distribution of the temperatures directly correlates with a spatial distribution of the inhomogeneities of the magnetic field. The currents are therefore set directly on the basis of the measured temperature distribution, which enables a quick and effective possibility of compensating for inhomogeneities.
In another advantageous embodiment of the method, a frequency of a frequency generator for a transmit coil of the magnetic resonance tomography system is varied based on the measured temperatures. For this purpose, the magnetic resonance tomography system advantageously includes a frequency generator for a transmit coil, which frequency generator is connected on the data input side to the compensation system. Although inhomogeneities of the magnetic field may be compensated by the aforementioned method, the measures carried out, such as changing the temperature in the shield or overlaying additional fields of shim coils, may result in a shift in the field strength of the (now homogeneous) magnetic field overall. The shift involves a change in the Larmor frequency of the nuclear spins of the object that is to be examined, which provides that other frequencies of the transmit coil are required for the nuclear spin excitation. If the measured temperature shifts are passed on directly to the frequency generator, the shift may be directly compensated for by an adjustment of the excitation frequencies.
While a measurement is performed, the magnetic resonance tomography system is advantageously operated according to the described method, e.g., the MRT system is advantageously designed to compensate for the effects of temperature differences on the homogeneity of the magnetic field during the performance of a measurement. In other words, the compensation based on corresponding temperature adjustment of the shield and/or adjustment of the currents to the shim coils is performed continuously during the measurement. This enables changes in temperature occurring during an examination, e.g., due to spontaneous changes in incident solar radiation as a result of clearing cloud cover or the like, to be continuously compensated, thus further optimizing the image quality.
A mobile magnetic resonance tomography system is advantageously operated by the described method.
A motorized vehicle or motorized vehicle trailer is advantageously equipped with a magnetic resonance tomography system.
The advantages achieved include that the image quality in mobile MRT systems is considerably improved as a result of the compensation of inhomogeneities of the magnetic field in an MRT system by temperature regulation or appropriate shimming. Influences affecting the magnetic field due to thermal expansion or changes in the susceptibility of the shield are neutralized. The system is comparatively inexpensive, since only temperature sensors, where appropriate planar heating elements and sensing electronics are required, while the remaining aspects of the system may be realized in software.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a section through a part of an embodiment of a mobile magnetic resonance tomography system in a trailer of a tractor-trailer unit with auxiliary coils actuated as a function of temperature.
FIG. 2 depicts a section through a part of an embodiment of a mobile magnetic resonance tomography system in a trailer of a tractor-trailer unit with heating elements actuated as a function of temperature.
DETAILED DESCRIPTION
FIG. 1 schematically depicts a cross-section through a part of a mobile magnetic resonance tomography system 1 . The mobile MRT system 1 is mounted on a trailer 2 of a motorized tractor vehicle. The essentially box-shaped cargo bay 4 and the wheels 6 are depicted in the sectional view of FIG. 1 . A cylinder-barrel-shaped magnet 8 and a patient support surface 10 arranged in the interior of the magnet 8 are depicted in FIG. 1 . Other parts such as transmit and receive coils and the evaluation unit are not shown.
The magnet 8 serves to generate a comparatively strong homogeneous magnetic field B 0 . In the magnetic field, previously degenerate energy levels of the atomic nuclei split up and exhibit an energy gap of ΔE=g B 0 (in natural units). The energy gap corresponds to a frequency, also referred to as the Larmor frequency. The principle of the MRT measurement is briefly explained below.
The actual measurement is carried out according to the principle of the so-called spin echo sequence. In this context, a “sequence” (also “pulse sequence”) refers to a combination of radio frequency pulses and magnetic gradient fields of specific frequency or strength that are switched on and off multiple times every second in a predetermined order. At the start stands a radio frequency pulse of the matching Larmor frequency, the so-called 90° excitation pulse. By the pulse, the magnetization is deflected through 90° at right angles to the external magnetic field and begins to gyrate around the original axis (precession).
The radio frequency signal resulting therein may be measured outside of the body. The radio frequency signal decreases exponentially because the proton spins fall out of “time” (“dephase”) and increasingly destructively overlay one another. The time after which 63% of the signal has decayed is called the relaxation time (spin-spin relaxation). This time is dependent on the chemical environment of the hydrogen and is different for each tissue type. Tumor tissue, for example, may have a longer time than normal muscle tissue. For this reason, a weighted measurement represents the tumor brighter than its environment.
In order to enable the measured signals to be assigned to the individual volume elements (voxels), a spatial encoding is generated by linearly location-dependent magnetic fields (gradient fields). In this case, use is made of the fact that for a specific particle the Larmor frequency is dependent on the magnetic flux density (the stronger the field component perpendicularly to the direction of the particle angular momentum, the higher the Larmor frequency). A gradient is applied during the excitation and provides that a single slice of the body possesses the matching Larmor frequency, e.g., only the spins of the slice are deflected (slice selection gradient). A second gradient at right angles to the first is switched on briefly after the excitation and causes a controlled dephasing of the spins in such a way that the precession of the spins has a different phase position (phase-encoding gradient) in each image row. A third gradient is switched during the measurement at right angles to the two others. The third gradient provides that the spins of each image column have a different precession velocity or, in other words, send a different Larmor frequency (readout gradient, frequency encoding gradient). All three gradients together therefore effect an encoding of the signal in three spatial planes.
The measurement method described makes clear that a precise knowledge of the locally present magnetic field strength is necessary for the spatial encoding. Since the additional gradient fields are relatively weak in comparison with the underlying magnetic field B 0 , this requires a greatest possible homogeneity of the magnetic field B 0 . For this purpose, planar shields 14 made of iron are initially arranged on the walls of the trailer 2 in the mobile MRT system 1 according to FIG. 1 in order to prevent the residual stray field of the magnet in the exterior space of the trailer 2 from exceeding a magnitude of approximately 0.5 millitesla (mT).
Compensating for non-shielded residual stray fields is achieved by the technique known as shimming. With this, auxiliary coils 12 (also referred to as shim coils), of which a single auxiliary coil 12 encircling the magnet 8 is depicted in the exemplary embodiment of FIG. 1 , are arranged at different locations in the region of the MRT system 1 . The auxiliary coil 12 may also be arranged elsewhere, for example, inside a gradient coil of the MRT system 1 .
The auxiliary coils 12 for the shimming are constructed such that their fields may be described in the sample by spherical harmonic functions, since interference fields whose cause lies spatially distant from the sample have in the latter likewise (approximately) the form of such low-order spherical harmonic functions. Applying electric current to the auxiliary coils 12 in a targeted manner results in correction fields being generated that overlay and homogenize the field of the magnet 8 .
In mobile MRT systems 1 , this, however, gives rise to the additional problem that differences in the heating-up and cooling-down of the shield 14 occur depending on meteorological conditions. Thermally insulating the shield 14 is possible to a limited extent, since the space available in the cargo bay 4 is constrained due to the permissible external dimensions of the trailer 2 under road traffic regulations. For this reason, the MRT system 1 according to FIG. 1 is designed for active compensation of the temperature differences.
For this purpose, the MRT system 1 according to FIG. 1 has a temperature measuring system 16 including a plurality of connected temperature sensors 18 . In this arrangement, the temperature sensors 18 are distributed along the shield 14 , with ten (merely by way of example) temperature sensors 18 being visible in FIG. 1 on account of the cross-section. In total, around fifty temperature sensors 18 are distributed, including on the floor and ceiling of the trailer 2 . This enables an accurate, three-dimensional temperature distribution to be determined.
The temperature distribution is determined and evaluated by a compensation system 20 . The compensation device 20 in turn controls the actuation of the auxiliary coils 12 with current. In this case, use is made of the fact that the local distribution of the temperature directly correlates with the inhomogeneity of the magnetic field corresponding thereto. Thus, for example, if a temperature gradient is present in a given spatial direction, then a field strength gradient will also be present in the same spatial direction.
Since the auxiliary coils 12 generate fields having a distribution according to spherical harmonic functions, the compensation device performs an eigenvalue analysis of the temperature distribution matrix in respect of the system of spherical harmonic functions representing the basis vectors. The determined eigenvalues are then used as a measure of the strength of the current that is to be supplied to the auxiliary coil 12 corresponding in each case to the associated spherical harmonic function. The inhomogeneities are compensated as a result.
In this case, the compensation may also be carried out continuously during a measurement. If the temperatures change during a measurement, e.g., due to strengthening sunshine, the shim of the magnet 8 may thus be constantly correctively adjusted.
The compensation system 20 is additionally connected to a frequency generator for the transmit coil of the MRT system 1 . Although the compensation system 20 may restore a homogeneity of the magnetic field B 0 of the magnet 8 , the compensation system 20 may nonetheless happen that the value of the field strength B 0 changes. The changes caused by the compensation system 20 in the shim currents to the auxiliary coils 12 and the measured temperature deviations are therefore used in order to determine the correction of the B 0 value and adjust the examination frequency, which corresponds to the changed Larmor frequency, accordingly. The adjustment may in this case be carried out in addition to a non-temperature-sensitive frequency adjustment.
FIG. 2 depicts an alternative embodiment, which is explained with reference to its differences from FIG. 1 . In this embodiment, the compensation system 20 does not control the shim currents to the auxiliary coils 12 . Instead, the compensation system 20 has a plurality of heating elements 22 that are embodied as planar heating elements or heating foils and allocated accordingly to the temperature sensors 18 .
In the exemplary embodiment according to FIG. 2 , the compensation system 20 determines the highest measured temperature over all of the temperature sensors 18 . The heating elements 22 are selectively actuated with current such that the temperature at all temperature sensors 18 is brought to the same value. In this case, therefore, the temperature distribution itself is homogenized. Analogously to the exemplary embodiment of FIG. 1 , the examination frequency is in this case likewise adjusted to the changed B0 value.
It is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent, and that such new combinations are to be understood as forming a part of the present specification.
While the present invention has been described above by reference to various embodiments, it may be understood that many changes and modifications may be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.
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A method for operating a mobile magnetic resonance tomography system having magnets and/or coils generating a magnetic field and a shield surrounding the magnets and/or coils is intended to enable an optimal image quality during the examination and at the same time have a small space requirement. For this purpose, a temperature is measured at a plurality of points on the shield by a temperature measuring system, where measured data of the temperature measuring system is sent to a compensation system, and where effects of temperature differences on the homogeneity of the magnetic field are compensated by the compensation system.
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This application is a continuation of U.S. Ser. No. 10/003,640, filed Nov. 2, 2001, now abandoned, which is a continuation in part of U.S. Ser. No. 09/698,527, filed Oct. 27, 2000, which issued as U.S. Pat. No. 6,462,169 on Oct. 8, 2002.
BACKGROUND OF THE INVENTION
Since the successful development of crystalline thermoplastic polyglycolide as an absorbable fiber-forming material, there has been a great deal of effort directed to the development of new linear fiber-forming polyesters with modulated mechanical properties and absorption profiles. Such modulation was made possible through the application of the concept of chain segmentation or block formation, where linear macromolecular chains comprise different chemical entities with a wide range of physicochemical properties, among which is the ability to crystallize or impart internal plasticization. Typical examples illustrating the use of this strategy are found in U.S. Pat. Nos. 5,554,170, 5,431,679, 5,403,347, 5,236,444, and 5,133,739, where difunctional initiators were used to produce linear crystallizable copolymeric chains having different microstructures.
On the other hand, controlled branching in crystalline, homochain polymers, such as polyethylene, has been used as a strategy to broaden the distribution in crystallite size, lower the overall degree in crystallinity and increase compliance (L. Mandelkern, Crystallization of Polymers, McGraw-Hill Book Company, NY, 1964, p. 105–106). A similar but more difficult-to-implement approach to achieving such an effect on crystallinity as alluded to above has been used specifically in the production of linear segmented and block heterochain copolymers such as (1) non-absorbable polyether-esters of polybutylene terephthalate and polytetramethylene oxide [see S. W. Shalaby and H. E. Bair, Chapter 4 of Thermal Characterization of Polymeric Materials (E. A. Turi, Ed.) Academic Press, NY, 1981, p. 402; S. W. Shalaby et al., U.S. Pat. No. 4,543,952 (1985)]; (2) block/segmented absorbable copolymers of high melting crystallizable polyesters such as polyglycolide with amorphous polyether-ester such as poly-1,5-dioxepane-2-one (see A. Kafrawy et al., U.S. Pat. No. 4,470,416 (1984)); and (3) block/segmented absorbable copolyesters of crystallizable and non-crystallizable components as cited in U.S. Pat. Nos. 5,554,170, 5,431,679, 5,403,347, 5,236,444, and 5,133,739. However, the use of a combination of controlled branching (polyaxial chain geometry) and chain segmentation or block formation of the individual branches to produce absorbable polymers with tailored properties cannot be found in the prior art. This and recognized needs for absorbable polymers having unique combinations of crystallinity and high compliance that can be melt-processed into high strength fibers and films with relatively brief absorption profiles as compared to their homopolymeric crystalline analogs provided an incentive to explore a novel approach to the design of macromolecular chains to fulfill such needs. Meanwhile, initiation of ring-opening polymerization with organic compounds having three or four functional groups have been used as a means to produce crosslinked elastomeric absorbable systems as in the examples and claims of U.S. Pat. No. 5,644,002. Contrary to this prior art and in concert with the recognized needs for novel crystallizable, melt-processable materials, the present invention deals with the synthesis and use of polyaxial initiators with three or more functional groups to produce crystallizable materials with melting temperatures above 100° C., which can be melt-processed into highly compliant absorbable films and fibers.
SUMMARY OF THE INVENTION
In one aspect the present invention is directed to an absorbable, crystalline, monocentric, polyaxial copolymer which includes a central atom which is carbon or nitrogen and at least three axes originating and extending outwardly from the central atom, each axis including an amorphous, flexible component adjacent to and originating from the central atom, the amorphous component being formed of repeat units derived from at least one cyclic monomer, either a carbonate or a lactone, and a rigid, crystallizable component extending outwardly from the amorphous, flexible component, the crystallizable component being formed of repeat units derived from at least one lactone, wherein the copolymer comprises a melting temperature greater than 120° C., a heat of fusion greater than 10 J/g, and an endothermic transition at 40–100° C., wherein the endothermic transition can be controlled by subsequent heat treatment, such as orientation or annealing, of the copolymer. In one embodiment, a composite cover or mantle for a stent which includes a polymeric matrix reinforced with monofilament cross-spirals may be provided wherein the matrix, the monofilaments or both may be made of the copolymer of the present invention.
The flexible polyaxial initiator can be derived from p-dioxanone, 1,5-dioxepan-2-one, or one of the following mixtures of polymers: (1) trimethylene carbonate and 1,5-dioxepan-2-one with or without a small amount of glycolide; (2) trimethylene carbonate and a cyclic dimer of 1,5-dioxepan-2-one with or without a small amount of glycolide; (3) caprolactone and p-dioxanone with or without a small amount of glycolide; (4) trimethylene carbonate and caprolactone with or without a small amount of dl-lactide; (5) caprolactone and dl-lactide with or without a small amount of glycolide; and (6) trimethylene carbonate and dl-lactide with or without a small amount of glycolide. Further, the crystallizable segment can be derived from glycolide or l-lactide. Alternate precursors of the crystallizable segment can be a mixture that is predominantly glycolide or l-lactide with a minor component of one or more of the following monomers: p-dioxanone, 1,5-dioxepan-2-one, trimethylene carbonate, and caprolactone.
In another embodiment the present invention is directed to a device for sealing a puncture in a blood vessel, which includes a first flexible sealing member, which is positionable inside the blood vessel immediately adjacent to the puncture; an elongated member which is a composite and has an axial direction, a cross-sectional diameter, a proximal end and a distal end, wherein the first sealing member is attached to the distal end of the elongated member, the elongated member is capable of positioning the first sealing member within the blood vessel and immediately adjacent to the puncture, the elongated member further includes a distal locking portion comprising an enlarged cross-sectional diameter at the distal portion which extends outwardly from the punctured blood vessel when the first sealing member is positioned within the blood vessel and immediately adjacent to the puncture; and a second flexible sealing member threadable onto the elongated member by an opening defined therein, the second sealing member comprising locking means for locking onto the distal locking portion of the elongated member, such that the second sealing means is locked onto the elongated member on the outside of the blood vessel immediately adjacent to the puncture thereby sealing the puncture. Preferably, the locking means of the second sealing member comprises the opening defined therein having a diameter less than the enlarged cross-sectional diameter of the distal locking portion of the elongated member such that the second flexible sealing member is capable of stretching the opening defined therein for frictional engagement with the distal locking portion of the elongated member. Alternatively, the locking means of the second sealing member is a further flexible member threadable onto the elongated member having an opening defined therein which has a diameter less than the enlarged cross-sectional diameter of the distal locking portion of the elongated member, the further flexible member being capable of stretching the opening defined therein for frictional engagement with the distal locking portion of the elongate member, wherein the further flexible member is locked immediately adjacent to the second sealing member and opposite to the puncture of the blood vessel.
Preferably, either the first sealing member, the second sealing member or both is a formed from an absorbable polymer. Most preferably, at least one of the first sealing member and the second sealing member comprise an absorbable, crystalline, monocentric, polyaxial copolymer which includes a central atom selected from the group consisting of carbon and nitrogen; and at least three axes originating and extending outwardly from the central atom, each axis including: an amorphous, flexible component adjacent to and originating from the central atom, the amorphous component consisting of repeat units derived from at least one cyclic monomer selected from the group consisting essentially of carbonates and lactones; and a rigid, crystallizable component extending outwardly from the amorphous, flexible component, the crystallizable component consisting of repeat units derived from at least one lactone.
Preferably, the elongated member comprises a composite of a highly flexible sheath and a less flexible solid, monofilament core, the less flexible core within the sheath comprising the enlarged cross-sectional diameter of the distal locking portion of the elongated member composite. It is preferred that the sheath is a braided suture and the less flexible filament is threaded through the interior portion of the suture. It is also preferred that the ends of the filament are tapered. In one embodiment the less flexible filament is sufficiently flexible to compress and frictionally engage the opening defined within the second sealing member.
According to still another aspect of the present invention the subject copolymer is converted to different forms of absorbable stents, a tubular mantle (or cover) for stents, sutures, sealing devices or parts of multicomponent sealing devices for closing (or plugging) a wound or a needle hole in a wall of a blood vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other aspects of the present invention will be best appreciated with reference to the following detailed description of specific embodiments of the invention, given by way of example only, when read in conjunction with the accompanying drawing, wherein
FIG. 1 shows a sealing device for closing a wound in a wall of a vessel according to a first embodiment of a first specific application of the invention;
FIG. 2 shows a sectional view of a first sealing member;
FIG. 3 shows a sectional view of a second sealing member;
FIG. 4 shows a sealing device for closing a wound in a wall of a vessel according to a first embodiment of a first specific application of the invention;
FIG. 5 shows an elongated core;
FIG. 6 shows a sealing device for closing a wound in a wall of a vessel according to a second embodiment of a first specific application of the invention;
FIG. 7 shows a sealing device for closing a wound in a wall of a vessel according to a third embodiment of a first specific application of the invention;
FIG. 8 shows a sealing device for closing a wound in a wall of a vessel according to a fifth embodiment of a first specific application of the invention;
FIG. 9 shows a sealing device for closing a wound in a wall of a vessel according to a fifth embodiment of a first specific application of the invention;
FIG. 10 shows schematically a prior art stent applicable in the present invention;
FIG. 11 is a longitudinal view of a stent according to a preferred embodiment of the present invention;
FIG. 12 is a cross sectional view of the stent shown in FIG. 11 ; and
FIG. 13 is a longitudinal view of a stent according to another preferred embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
This invention deals with absorbable, polyaxial, monocentric, crystallizable, polymeric molecules with non-crystallizable, flexible components of the chain at the core and rigid, crystallizable segments at the chain terminals. More specifically, the present invention is directed to the design of amorphous polymeric polyaxial initiators with branches originating from one polyfunctional organic compound so as to extend along more than two coordinates and their copolymerization with cyclic monomers to produce compliant, crystalline film- and fiber-forming absorbable materials. The absorbable copolymeric materials of this invention comprise at least 30 percent, and preferably 65 percent, by weight, of a crystallizable component which is made primarily of glycolide-derived or l-lactide-derived sequences, and exhibit first and second order transitions below 222° C. and below 42° C., respectively, and undergo complete dissociation into water-soluble by-products in less than eighteen months and preferably less than twelve months, and more preferably less than six months, and much more preferably less than four months when incubated in a phosphate buffer at 37° C. and pH 7.4 or implanted in living tissues.
The amorphous polymeric, polyaxial initiators (PPIs) used in this invention to produce crystalline absorbable copolymeric materials can be made by reacting a cyclic monomer or a mixture of cyclic monomers such as trimethylene carbonate, caprolactone, and 1,5-dioxapane-2-one in the presence of an organometallic catalyst with one or more polyhydroxy, polyamino, or hydroxyamino compound having three or more reactive amines and/or hydroxyl groups. Typical examples of the latter compounds are glycerol and ethane-trimethylol, propane-trimethylol, pentaerythritol, triethanolamine, and N-2-aminoethyl-1,3-propanediamine.
The flexible polyaxial initiator can be derived from p-dioxanone, 1,5-dioxepan-2-one, or one of the following mixtures of polymers: (1) trimethylene carbonate and 1,5-dioxepan-2-one with or without a small amount of glycolide; (2) trimethylene carbonate and a cyclic dimer of 1,5-dioxepan-2-one with or without a small amount of glycolide; (3) caprolactone and p-dioxanone with or without a small amount of glycolide; (4) trimethylene carbonate and caprolactone with or without a small amount of dl-lactide; (5) caprolactone and dl-lactide (or meso-lactide) with or without a small amount of glycolide; and (6) trimethylene carbonate and dl-lactide (or meso-lactide) with or without a small amount of glycolide. Further, the crystallizable segment can be derived from glycolide or l-lactide. Alternate precursors of the crystallizable segment can be a mixture of predominantly glycolide or l-lactide with a minor component of one or more of the following monomers: p-dioxanone, 1,5-dioxepan-2-one, trimethylene carbonate, and caprolactone.
The crystalline copolymers of the present invention are so designed to (1) have the PPI devoid of any discernable level of crystallinity; (2) have the PPI component function as a flexible spacer of a terminally placed, rigid, crystallizable component derived primarily from glycolide so as to allow for facile molecular entanglement to create pseudo-crosslinks, which in turn, maximize the interfacing of the amorphous and crystalline fractions of the copolymer leading to high compliance without compromising tensile strength; (3) maximize the incorporation of the hydrolytically labile glycolate linkage in the copolymer without compromising the sought high compliance—this is achieved by directing the polyglycolide segments to grow on multiple active sites of the polymeric initiator and thus limiting the length of the crystallizable chain segments; (4) have a broad crystallization window featuring maximum nucleation sites and slow crystallite growth that in turn assists in securing a highly controlled post-processing and development of mechanical properties—this is achieved by allowing the crystallizable components to entangle effectively with non-crystallizable components leading to high affinity for nucleation, high pre-crystallization viscosity, slow chain motion, and low rate of crystallization; (5) force the polymer to form less perfect crystallites with broad size distribution and lower their melting temperature as compared to their homopolymeric crystalline analogs to aid melt-processing—this is achieved by limiting the length of the crystallizable segments of the copolymeric chain as discussed earlier; (6) allow for incorporating basic moieties in the PPI which can affect autocatalytic hydrolysis of the entire system which in turn accelerates the absorption rate; and (7) allow the polymer chain to associate so as to allow for endothermic thermal events to take place between 40 and 100° C. that can be associated with an increase in tensile toughness similar to that detected in PET relative to the so-called middle endothermic peak (MEP) (S. W. Shalaby, Chapter 3 of Thermal Characterization of Polymeric Materials, Academic press, NY, 1981, p. 330). The temperature at which these transitions take place is dependent on the degree of orientation of the polymers of this invention and the temperatures at which the polymers are annealed.
As an example, the crystalline copolymeric materials of the present invention may be prepared as follows, although as noted above, other monomers are also within the scope of the present invention. The amorphous polymeric polyaxial initiator is formed by a preliminary polymerization of a mixture of caprolactone and trimethylene carbonate in the presence of trimethylol-propane and a catalytic amount of stannous octoate, using standard ring-opening polymerization conditions which entail heating the stirred reactants in nitrogen atmosphere at a temperature exceeding 110° C. until substantial or complete conversion of the monomers is realized. This can be followed by adding a predetermined amount of glycolide. Following the dissolution of the glycolide in the reaction mixture, the temperature is raised above 150° C. but not to exceed 180° C. for more than 30 minutes to allow the glycolide to copolymerize with the polyaxial initiator without compromising the expected sequence distribution in PPI and the microtexture of the crystallizable terminal. When practically all the glycolide is allowed to react, the resulting copolymer is cooled to 25° C. After removing the polymer from the reaction kettle and grinding, trace amounts of unreacted monomer are removed by heating under reduced pressure. The ground polymer can then be extruded and pelletized prior to its conversion to fibers or films by conventional melt-processing methods. At the appropriate stage of polymerization and product purification, traditional analytical methods, such as gel-permeation chromatography (GPC), solution viscosity, differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), and infrared spectroscopy (IR) are used to monitor or determine (directly or indirectly) the extent of monomer conversion, molecular weight, thermal transitions (melting temperature, T m , and glass transition temperature, T g ), chain microstructure, and chemical entity, respectively.
Another aspect of this invention deals with end-grafting a PPI with caprolactone or l-lactide, and preferably in the presence of a minor amount of a second monomer, to produce absorbable crystalline polymers for use as bone sealants, barrier membranes, thin films, or sheets. The latter three can be made to have continuous cell microporous morphology.
Films made by compression molding of the copolymers described in the examples set forth below are evaluated for (1) tensile strength; (2) in vitro breaking strength retention and mass loss during incubation in a phosphate buffer at 37° C. and pH 7.4; (3) in vivo breaking strength retention using a rat model where strips of the films are implanted subcutaneously for 1 to 6 weeks and individual lengths are explanted periodically to determine percent of retained breaking strength; and (4) in vivo absorption (in terms of mass loss) using a rat model where a film strip, inserted in a sealed polyethylene terephthalate (PET) woven bag, is placed in the peritoneum for 6, 8, 10, 12 and 14 weeks. At the end of each period, the PET bag is removed and the residual mass of the strips is removed, rinsed with water, dried, and its weight is determined.
Specifically, an important aspect of this invention is the production of compliant absorbable films with modulated absorption and strength loss profiles to allow their use in a wide range of applications as vascular devices or components therefor. More specifically is the use of these devices in sealing punctured blood vessels.
In another aspect, this invention is directed to the use of the polymers described herein for the production of extruded or molded films for use in barrier systems to prevent post-surgical adhesion or compliant covers, sealants, or barriers for burns and ulcers as well as compromised/damaged tissue. The aforementioned articles may also contain one or more bioactive agent to augment or accelerate their functions. In another aspect, this invention is directed to melt-processed films for use to patch mechanically compromised blood vessels. In another aspect, this invention is directed to the use of the polymer described herein as a coating for intravascular devices such as catheters and stents. In another aspect, this invention is directed to the application of the polymers described herein in the production of extruded catheters for use as transient conduits and microcellular foams with continuous porous structure for use in tissue engineering and guiding the growth of blood vessels and nerve ends. Another aspect of this invention is directed to the use of the polymers described herein to produce injection molded articles for use as barriers, or plugs, to aid the function of certain biomedical devices used in soft and hard tissues and which can be employed in repairing, augmenting, substituting or redirecting/assisting the functions of several types of tissues including bone, cartilage, and lung as well as vascular tissues and components of the gastrointestinal and urinogenital systems. In another aspect, this invention is directed to the use of polymers described herein to produce compliant, melt-blown fabrics and monofilament sutures with modulated absorption and strength retention profiles.
In one aspect of this invention, the subject copolymers are converted to different forms of absorbable stents, such as those used (1) as an intraluminal device for sutureless gastrointestinal sutureless anastomosis; (2) in laparoscopic replacement of urinary tract segments; (3) as an intraluminal device for artery welding; (4) in the treatment of urethral lesions; (5) as a tracheal airway; (6) in the treatment of recurrent urethral strictures; (7) for vasectomy reversal; (8) in the treatment of tracheal stenoses in children; (9) for vasovasostomy; (10) for end-to-end ureterostomy; and (11) as biliary devices.
In another aspect of this invention, the subject copolymers are converted to a highly compliant, expandable tubular mantle, sleeve or cover that is placed tightly outside an expandable metallic or polymeric stent so that under concentric irreversible expansion at the desired site of a treated biological conduit, such as blood vessel or a urethra, both components will simultaneously expand and the mantle provides a barrier between the inner wall of the conduit and the outer wall of the stent. In another aspect of this invention, the subject copolymers are used as a stretchable matrix of a fiber-reinforced cover, sleeve, or mantle for a stent, wherein the fiber reinforcement is in the form of spirally coiled yarn (with and without crimping) woven, knitted, or braided construct. In another aspect of this invention, the stent mantle, or cover, is designed to serve a controlled release matrix of bioactive agents such as those used (1) for inhibiting neointima formation as exemplified by hirudin and the prostacyclic analogue, iloprost; (2) for inhibiting platelet aggregation and thrombosis; (3) for reducing intraluminal and particular intravascular inflammation as exemplified by dexamethasone and non-steroidal inflammatory drugs, such as naproxen; and (4) for suppressing the restenosis.
One aspect of this invention deals with the conversion of the subject copolymers into molded devices or components of devices used as a hemostatic puncture closure device after coronary angioplasty.
It is further within the scope of this invention to incorporate one or more medico-surgically useful substances into the copolymers and devices subject of this invention. Typical examples of these substances are those capable of (1) minimizing or preventing platelet adhesion to the surface of vascular grafts; (2) rendering anti-inflammatory functions; (3) blocking incidents leading to hyperplasia as in the case of synthetic vascular grafts; (4) aiding endothelialization of synthetic vascular grafts; (5) preventing smooth muscle cell migration to the lumen of synthetic vascular grafts; and (6) accelerating guided tissue ingrowth in fully or partially absorbable scaffolds used in vascular tissue engineering.
In order that those skilled in the art may be better able to practice the present invention, the following illustrations of the preparation of typical crystalline copolymers are provided.
EXAMPLE 1
Synthesis of 20/25 (Molar) Caprolactone/Trimethylene Carbonate Copolymer as a Triaxial Initiator and Reaction with 55 Relative Molar Parts of Glycolide
An initial charge consisted of 142.4 grams (1.249 moles) caprolactone, 159.4 grams (1.563 moles) trimethylene carbonate, 1.666 grams (1.24×10 −2 moles) trimethylol-propane, and 1.0 ml (2.03×10 −4 moles) of a 0.203M solution of stannous octoate catalyst in toluene after flame drying the reaction apparatus. The reaction apparatus was a 1 L stainless steel kettle with 3-neck glass lid equipped with an overhead mechanical stirring unit, vacuum adapter, and two 90° connectors for an argon inlet.
The apparatus and its contents were heated to 50° C. under vacuum with a high temperature oil bath. Upon complete melting of the contents after 30 minutes, the system was purged with argon, stirring initiated at 32 rpm, and the temperature set to 150° C. After 4 hours at 150° C., the viscosity of the polyaxial polymeric initiator (PPI) had increased and the temperature of the bath was reduced to 110° C. Upon reaching 110° C., 398.5 grams (3.435 moles) of glycolide were added to the system. When the glycolide had completely melted and mixed into the polyaxial polymeric initiator, the temperature was increased to 180° C. and stirring was stopped. The reaction was allowed to continue for 2 hours before cooling the system to 50° C. and maintaining the heat overnight. The polymer was isolated, ground, dried, extruded and redried as described below in Example 5.
The extrudate was characterized as follows: The inherent viscosity using hexafluoroisopropyl alcohol (HFIP) as a solvent was 0.97 dL/g. The melting temperature and heat of fusion, as determined by differential scanning calorimetry (using initial heating thermogram), were 215° C. and 40.8 J/g, respectively.
EXAMPLE 2
Synthesis of 25/30 (molar) Caprolactone/Trimethylene Carbonate Copolymer as a Triaxial Initiator and Reaction with 45 Relative Molar Parts of Glycolide
An initial charge consisted of 122.8 grams (1.077 moles) caprolactone, 131.9 grams (1.292 moles) trimethylene carbonate, 1.928 grams (1.44×10 −2 moles) trimethylol-propane, and 1.0 ml (8.62×10 −5 moles) of a 0.086M solution of stannous octoate catalyst in toluene after flame drying the reaction apparatus. The reaction apparatus was a 1 L stainless steel kettle with 3-neck glass lid equipped with an overhead mechanical stirring unit, vacuum adapter, and two 90° connectors for an argon inlet.
The apparatus and its contents were then heated to 65° C. under vacuum with a high temperature oil bath. After 30 minutes, with the contents completely melted, the system was purged with argon, stirring initiated at 34 rpm, and the temperature set to 140° C. After 3 hours at 140° C., the temperature was raised to 150° C. for 1 hour and then reduced back to 140° C. At this point, 225.0 grams (1.940 moles) of glycolide were added to the system while rapidly stirring. When the glycolide had completely melted and mixed into the polyaxial polymeric initiator, the temperature was increased to 180° C. and stirring was stopped. The reaction was allowed to continue for 2 hours before cooling the system to room temperature overnight. The polymer was isolated, ground, dried, extruded, and redried as described in Example 5.
Characterization of the extrudate was conducted as follows: The inherent viscosity using HFIP as a solvent was 0.93 dL/g. The melting temperature and heat of fusion, as measured by differential scanning calorimetry (DSC using initial heating thermogram), were 196° C. and 32.1 J/g, respectively.
EXAMPLE 3
Synthesis of 20/25/3 (molar) Caprolactone/Trimethylene Carbonate/Glycolide Copolymer as a Triaxial Initiator and Reaction with 52 Relative Molar Parts of Glycolide
An initial charge consisted of 101.6grams (0.891 moles) caprolactone, 113.5 grams (1.113 moles) trimethylene carbonate, 15.5 grams of glycolide (0.134 moles), 1.996 grams (1.49×10 −2 moles) trimethylol-propane, and 1.0 ml (1.28×10 −4 moles) of a 0.128M solution of stannous octoate catalyst in toluene after flame drying the reaction apparatus. The reaction apparatus was a 1 L stainless steel kettle with 3-neck glass lid equipped, an overhead mechanical stirring unit, vacuum adapter, and two 90° connectors for an argon inlet.
The apparatus and its contents were then heated to 85° C. under vacuum with a high temperature oil bath. After 30 minutes, with the contents completely melted, the system was purged with argon, stirring initiated at 34 rpm, and the temperature set to 140° C. After 4 hours at 140° C., 268.8 grams (2.317 moles) of glycolide were added to the system while rapidly stirring. When the glycolide had completely melted and mixed into the polyaxial polymeric initiator, the temperature was increased to 180° C. and stirring was stopped. The reaction was allowed to continue for 2 hours before cooling the system to room temperature overnight. The polymer was isolated, ground, dried, extruded and redried as in Example 5.
The extrudate was characterized as follows: The inherent viscosity using HFIP as a solvent was 0.89 dL/g. The melting temperature and heat of fusion, as measured by differential scanning calorimetry (DSC using initial heating thermogram), were 212° C. and 34 J/g, respectively.
EXAMPLE 4
Synthesis of 20/25/3 (Molar) Caprolactone/Trimethylene-Carbonate/Glycolide Copolymer as a Triaxial Initiator and Reaction with 52 Relative Molar Parts of Glycolide
Glycolide (18.6 g, 0.1603 mole), TMC (136.7 g, 1.340 mole), caprolactone (122.0 g, 1.070 mole), trimethylolpropane (2.403 g, 0.01791 mole) and stannous octoate catalyst (0.2M in toluene, 764 μL, 0.1528 mmol) were added under dry nitrogen conditions to a 1.0 liter stainless steel reaction kettle equipped with a glass top and a mechanical stirrer. The reactants were melted at 85° C. and the system was evacuated with vacuum. The system was purged with dry nitrogen and the melt was heated to 160° C. with stirring at 30 rpm. Samples of the prepolymer melt were taken periodically and analyzed for monomer content using GPC. Once the monomer content of the melt was found to be negligible, glycolide (322.5 g, 2.780 mole) was added with rapid stirring. The stir rate was lowered to 30 rpm after the contents were well mixed. The melt was heated to 180° C. Stirring was stopped upon solidification of the polymer. The polymer was heated for 2 hours at 180° C. after solidification. The resulting polymer was cooled to room temperature, quenched in liquid nitrogen, isolated, and dried under vacuum. The polymer was isolated, ground, redried, and extruded as described in Example 5. The extrudate was characterized by NMR and IR for identity and DSC (using initial heating thermogram) for thermal transition (T m =208° C., ΔH=28.0 J/g) and solution viscosity in hexafluoroisopropyl alcohol (η=0.92 dL/g).
EXAMPLE 5
Size Reduction and Extrusion of Polymers of Examples 1 through 4
The polymer was quenched with liquid nitrogen and mechanically ground. The ground polymer was dried under vacuum at 25° C. for two hours, at 40° C. for two hours, and at 80° C. for four hours. The polymer was melt extruded at 225° C. to 235° C. using a ½ inch extruder equipped with a 0.094 in die. The resulting filaments were water cooled. The average filament diameter was 2.4 mm. The filament was dried at 40° C. and 80° C. under vacuum for eight and four hours, respectively.
EXAMPLE 6
Compression-Molding of Polymers from Examples 3 and 4 to a Sealing Device for a Punctured Blood Vessel and Its Packaging
The compression molding process entailed exposing the polymer to an elevated temperature between two mold halves. When temperature of the mold halves exceeded the polymer melting temperature, pressure was applied to the mold and the material was allowed to flow into a predefined cavity of the mold. The mold was then cooled to room temperature before it was opened and the newly shaped polymer was removed.
The full molding cycle can be described as: (1) Drying—typical: temperature 80° C. during 2 hours; (2) Pre-heating, temperature increase—typical: pressure 5,000N, temperature from room temperature up to 200° C.; (3) Forming, constant temperature under high pressure—typical: pressure 50,000N, temperature 200° C.; (4) Cooling, temperature decrease under high pressure—typical: pressure 50,000N, temperature from 200° C. down to 50° C.; (5) Mold opening; (6) Annealing—typical: temperature 80° C. during 2 hours; and (7) Packaging—typically the device was removed from the mold and packaged under vacuum under a protective gas environment.
EXAMPLE 7
Synthesis of 13.3/17.7/2 (molar) Caprolactone/Trimethylene Carbonate/Glycolide Copolymer as a Triaxial Initiator and Reaction with Relative 67 Molar Parts of Glycolide
Glycolide (10.4 g, 0.090 mole), TMC (76.5 g, 0.750 mole), caprolactone (68.4 g, 0.600 mole), trimethylolpropane (1.995 g, 0.01487 mole) and stannous octoate catalyst (0.2M in toluene, 637 μL, 0.1274 mmole) were added under dry nitrogen conditions to a 1.0 liter stainless steel reaction kettle equipped with a glass top and a mechanical stirrer. The reactants were melted at 85° C. and the system was evacuated with vacuum. The system was purged with dry nitrogen and the melt was heated to 160° C. with stirring at 30 rpm. Samples of the prepolymer melt were taken periodically and analyzed for monomer content using GPC. Once the monomer content of the melt was found to be negligible, glycolide (344.5 g, 2.970 mole) was added with rapid stirring. The stir rate was lowered to 30 rpm after the contents were well mixed. The melt was heated to 180° C. Stirring was stopped upon solidification of the polymer. The polymer was heated for 2 hours at 180° C. after solidification. The resulting polymer was cooled to room temperature, quenched in liquid nitrogen, isolated, and dried under vacuum. The polymer was characterized by NMR and IR (for identity), DSC thermal transition (T m =215.7) and solution viscosity in hexafluoroisopropyl alcohol (η−0.95 dL/g).
EXAMPLE 8
Synthesis of 13.6/17.0/2.0 (molar) Caprolactone/Trimethylene Carbonate/Glycolide Copolymer as a Basic Triaxial Initiator and Reaction with Relative 67.4 Molar Parts of Glycolide and Trimethylene Carbonate
Glycolide (3.1 g, 0.0267 mole), TMC (23.0 g, 0.2255 mole), caprolactone (20.5 g, 0.1798 mole), triethanolamine (0.6775 g, 4.55 mmole) and stannous octoate catalyst (0.2M in toluene, 519 μL, 0.1038 mmole) were added under dry nitrogen conditions to a 0.5 Liter stainless steel reaction kettle equipped with a glass top and a mechanical stirrer. The reactants were melted at 85° C. and the system was evacuated with vacuum. The system was purged with dry nitrogen and the melt was heated to 160° C. with stirring at 30 rpm. Samples of the prepolymer melt were taken periodically and analyzed for monomer content using GPC. Once the monomer content of the melt was found to be negligible, glycolide (103.4 g, 0.8914 mole) was added with rapid stirring. The stir rate was lowered to 30 rpm after the contents were well mixed. The melt was heated to 180° C. Stirring was stopped upon solidification of the polymer. The polymer was heated for 2 hours at 180° C. after solidification. The resulting polymer was cooled to room temperature, quenched in liquid nitrogen, isolated, and dried under vacuum. The polymer was characterized for identity and composition (IR and NMR, respectively) and thermal transition by DSC (T m 220° C.) and molecular weight by solution viscometry (η=0.80 in hexafluoroisopropyl alcohol).
EXAMPLE 9
Synthesis of 13.6/17.0/2.0 (molar) Caprolactone/Trimethylene Carbonate/Glycolide Copolymer as a Basic Triaxial Initiator and Reaction with Relative 67.4 Molar Parts of Glycolide
The two-step polymerization was conducted as in Example 8 with the exception of using 0.6915 g triethanolamine and 693 μl of stannous octanoate solution. The final polymer was isolated and characterized as in Example 8 and it was shown to have a T m =221° C. and inherent viscosity (in HFIP)=0.82.
EXAMPLE 10
Synthesis of 13.3/17.7/2 (molar) Caprolactone/Trimethylene Carbonate/Glycolide Copolymer as a Tetra-axial Initiator and Reaction with Relative 67 Molar Parts of Glycolide
Glycolide (3.1 g, 0.0267 mole), TMC (23.0 g, 0.2255 mole), caprolactone (20.5 g, 0.1796 mole), pentaerythritol (0.600 g., 0.0044 mole) and stannous octoate catalyst (0.2 M in toluene, 193 μl, 0.0386 mmol) were placed under dry nitrogen conditions to a 0.5 L stainless steel reaction kettle equipped with a glass top and a mechanical stirrer. The polymerization charge was dried at 25° C. and 40° C. under reduced pressure for 60 and 30 minutes, respectively. The reactants were then melted at 85° C. and the system was purged with dry nitrogen. The melt was heated to 160° C. with stirring at 30 rpm. Samples of the prepolymer melt were taken periodically and analyzed for monomer content using GPC (gel permeation chromatography). Once the monomer content of the polymer melt was found to be negligible, glycolide (103.4 g., 0.8914 mole) was added with rapid stirring that is more than 40 rpm. The stirring rate was then lowered to 30 rpm after the contents were well mixed. The reactants were heated to 180° C. Stirring was stopped upon solidification of the polymer. The polymer was heated for 2 hours at 180° C. after solidification. The resulting polymer was cooled to room temperature, quenched in liquid nitrogen, isolated, and dried at 25° C. and then 40° C. under reduced pressure.
The final polymer was isolated and characterized as in Example 8 and it was shown to have a T m =219° C. and inherent viscosity (in HFIP)=0.98.
EXAMPLE 11
Size Reduction and Extrusion of Polymer from Examples 7 through 10
The polymer was quenched with liquid nitrogen and mechanically ground. The ground polymer was dried under vacuum at 25° C. for two hours, at 40° C. for two hours, and at 80° C. for four hours. The polymer was melt extruded at 235° C. to 245° C. using a ½ inch extruder equipped with a 0.094 in die. The resulting monofilament was quenched in an ice-water bath before winding. The monofilament was dried at 40° C. and under vacuum for four hours before orientation.
EXAMPLE 12
Orientation of Melt-Spun Monofilaments
Polymers of Examples 7 through 10 that had been extruded as described in Example 11 were oriented by two-stage drawing into monofilament sutures. Prior to drawing Example 7, monofilaments were pre-tensioned and annealed. The drawing was conducted at 90–100° C. in the first stage and 100–130° C. in the second stage. The overall draw ratio varied between 3.73× and 4.6×. A number of monofilaments were relaxed at 70° C. for 15 minutes to reduce their free shrinkage. Properties of the oriented monofilaments are summarized in Table I.
TABLE I
Drawing Conditions and Fiber Properties of Polymers from Examples 7 through 9
Origin of
Draw
Pre-Draw
Post-Draw
Free
Straight
Modu-
Elonga-
Extruded
Fiber
Draw
Temp.
Annealing
Relaxation
Shrinkage
Diameter
Strength
lus
tion
Polymer
Number
Ratio
(S1/S2)
(min/° C.)
(%)
(%)
(mil)
(Kpsi)
(Kpsi)
(%)
Example
7F-1
3.73×
95/130
35/65
—
4.4
13.4
75
444
22
7
7
7F-2
3.73×
95/130
35/65
2.3
1.8
15.1
53
182
36
7
7F-3
4.14×
95/120
30/65
—
4.2
10.2
66
434
19
7
7F-4
4.14×
95/120
30/65
3
1.5
11.0
61
257
31
8
8F-1
4.50×
100/120
—
—
3.1
10.2
71
195
26
9
9F-1
4.43×
100/130
—
—
2.1
10.6
72
230
27
10
10F-1
4.60×
95/120
—
—
2.4
12.6
57
158
25
EXAMPLE 13
Sterilization of Monofilament Sutures and Evaluation of Their In Vitro Breaking Strength Retention
Monofilament sutures Numbers 8F-1 and 9F-1 described in Table I were radiochemically sterilized in hermetically sealed foil packages that have been pre-purged with dry nitrogen gas, using 5 and 7.5 KGy of gamma radiation. The radiochemical sterilization process entails the use of 200–400 mg of Delrin (poly-formaldehyde) film as package inserts for the controlled release, radiolytically, of formaldehyde gas as described earlier by Correa et al., [Sixth World Biomaterials Congress, Trans Soc. Biomat., II, 992 (2000)]. The sterile monofilament sutures were incubated in a phosphate buffer at 37° C. and pH=7.4 to determine their breaking strength retention profile as absorbable sutures. Using the breaking strength data of non-sterile sutures (Table I), the breaking strength retention data of sterile sutures were calculated. A summary of these data is given in Table II. These data indicate all sutures retained measurable strength at two weeks in the buffer solution.
TABLE II
Tensile Properties and In Vitro Breaking Strength Retention
(BSR) of Radiochemically Sterilized Monofilament Sutures
Suture Number
9F-1
8F-1
Sterilization Dose (KGy)
5
7.5
5
7.5
Post-irradiation Tensile Properties
Tensile Strength (Kpsi)
66
68
67
65
Modulus (Kpsi)
266
254
269
263
Elongation (Kpsi)
30
35
31
30
BSR, % at
Week 1
70
57
82
72
Week 2
24
22
18
17
EXAMPLE 14
Synthesis of 21/30/4 (Molar) Caprolactone/Trimethylene Carbonate as a Triaxial Initiator and Reaction with 40/5 Relative Molar Parts of l-Lactide/Caprolactone
Glycolide (22.74 g, 0.2 mole), TMC (149.94 g, 1.47 mole), caprolactone (117.31 g, 1.03 mole), triethanolamine (1.34 g, 9 mmole), and stannous octoate (3.86×10 −4 mole as 0.2 M solution in toluene) were reacted in similar equipment and environment as those described in Example 7. The formation of the triaxial initiator was completed after heating at 180° C. for 160 minutes. The product was cooled to room temperature and a mixture of l-lactide (282.24 g., 1.96 mole) and caprolactone (27.93 g, 0.25 mole) were added under nitrogen atmosphere. The reactants were prepared for the second step of polymerization as described in Example 7. And the final polymer formation was completed after heating between 195–200° C. for 15 minutes until complete dissolution of triaxial initiator, and then heating for 23 hours at 140° C. The polymer was isolated, ground, dried, and heated under reduced pressure to remove residual monomer. The polymer was characterized by NMR and IR (for identity), DSC for thermal transition (T m =148° C., ΔH=19 J/g), and inherent viscometry (I.V.) in chloroform (for molecular weight, I.V.=1.14 dL/g).
EXAMPLE 15
Synthesis of 156/20 (Molar) Caprolactone/Trimethylene Carbonate Copolymer as Triaxial Initiator and Reaction with Relative 65 Molar Parts Glycolide
Using a similar scheme to that used in Example 7, the triaxial initiator was prepared using caprolactone (45.5 g, 0.399 mole), TMC (54.3 g, 0.532 mole), trimethylolpropane (0.713 g, 5.32 mmole) and stannous octoate (5.32×10 −5 mole as a 0.2 M solution in toluene) and a polymerization temperature and time of 160° C./5 hours. As in Example 7, glycolide (200.6 g, 1.729 mole) was allowed to end-graft onto the triaxial initiator in presence of D & C Violet #2 (0.15 g) at 180° C./5 hours. The polymer was isolated, purified, and characterized as in Example 7. It had an inherent viscosity in HFIP=0.66 dL/g, T m =225° C., ΔH=66 J/g.
EXAMPLE 16
Processing of Example 15 Copolymer into Monofilaments and Evaluation of Their Properties
Following a similar processing scheme to those used for the copolymer of Example 7 (as described in Examples 11 and 12), the respective monofilaments of Example 15 were produced and exhibited the following properties:
T m −214° C., ΔH=64 J/g
The DSC thermogram showed a minor endothermic transition at about 65° C.
Fiber Diameter=0.28 mm
Straight tensile strength=76 Kpsi
Modulus=335 Kpsi
Elongation=42%
The monofilaments were examined for breaking strength retention (BSR) after incubation in a phosphate buffer at 37° C. and pH=7.4. The percent BSR at one and two weeks was 72 and 24, respectively.
EXAMPLE 17
Synthesis of 15/20 (molar) Caprolactone/Trimethylene Carbonate Copolymer as Triaxial Initiator and Reaction with Relative 65 Molar Parts Glycolide
The triaxial initiator was prepared as in Example 15 with the exception of using (1) Triethanolamine as the monomeric initiator; (stannous octoate at ˜30% higher concentration; and (3) reaction time of 18 hours. End-grafting with glycolide was carried out as in Example 15. The purified polymer was shown to have inherent viscosity=0.94 dL/g, T m =220° C., and ΔH=81.1 J/g.
EXAMPLE 18
Processing of Example 17 Copolymer into Monofilaments and Evaluation of Their Properties
A monofilament suture was prepared from the copolymer of Example 17 and oriented following a similar scheme to that used in Example 16. The monofilaments exhibited the following properties:
T m −214° C., ΔH=53 J/g
A minor endothermic transition was observed in partially and fully oriented monofilament at about 60° C. and 90° C., respectively.
Fiber Diameter=0.29 mm
Straight tensile strength=78 Kpsi
Modulus=296 Kpsi
Elongation=58%
The monofilaments were examined for breaking strength retention at incubation in a phosphate buffer at 37° C. and pH=7.4. The percent BSR at one and two weeks was 78 and 51, respectively. In addition to the oriented monofilament described above, the copolymer of example 17 was extruded into microfilaments having a diameter of 60–120 μ. These were used without additional orientation in composite assembling as described in Example 19. These microfilaments displayed an elongation that exceeded 300%.
EXAMPLE 19
General Method for Assembling Composite Stent Mantle
The undrawn microfilaments from Example 18 were wrapped in two opposite directions on a Teflon rod having a diameter of 2–4 mm to provide a two-component, cross-spiral construct. Each constituent spiral was comprised of 1 to 10 turns/cm along the axis of the Teflon rod. While on the Teflon rod, the cross-spiral construct was coated with a solution (10–20% in dichloromethane, DCM) of the copolymer of Example 14. The coating process entails multiple steps of dipping and air-drying and was pursued until the desirable coating thickness is achieved (25–50μ). Complete removal of the solvent was achieved by replacing the composite on the Teflon rod under reduced pressure at 25° C. for 6–12 hours until a constant weight is realized. The composite tube (typically 2–5 cm long) was removed from the Teflon cylinder by gentle sliding. This was then cut to the desired length before sliding over a metallic stent.
As indicated above a number of different applications for the copolymer exist. Below two specific applications, namely a device for sealing punctured blood vessels and a stent, will be described more thoroughly.
FIG. 1 shows a sealing device for closing a wound in a wall of a vessel according to a first embodiment of the invention. The sealing device comprises three separate parts, namely a first sealing member 2 an elongated member 4 and a second sealing member 6 . The first sealing member 2 is attached to a distal end of the elongate member 4 . In this first embodiment of the sealing device, the first sealing member comprises two through openings 8 , 10 ( FIG. 2 ) through which a multifilament suture wire 12 is thread so as to make a pair of suture wires constituting the elongated member 4 .
The second sealing member 6 is provided with an opening 14 ( FIG. 3 ), which is adapted to the elongate member 4 , i.e. the opening 14 is greater than the thickness of the proximal portion of the elongate member 4 . With a structure like this the second sealing member 6 is threadable onto and along the elongate element 4 ( FIG. 1 ). The most distal portion of the elongate member 4 has a constant thickness that is slightly greater than the opening 14 of the second sealing member 6 and constitutes the distal lock portion 16 . This will allow for frictional engagement between inside of the opening 14 of the second sealing member 6 and the distal lock portion 16 of the elongate member 4 which makes the sealing device infinitely variable lockable along said distal lock portion 16 ( FIG. 4 ).
The multifilament suture wire 12 is preferably made of a resorbable material such as glycolic/lactide polymer The first sealing member 2 and second sealing member 6 are made of the flexible resorbable copolymer, preferably the present inventive copolymer.
The choice of using a suture wire for the elongated element 4 is very important for the security of the sealing device. It is within the scope of the present invention, but less preferred, to use the same material, e.g. a polymer, in the elongated member 4 as in the second sealing member 6 . Since polymer gives a very glossy surface, it is hard to get high power frictional engagement between the elongated member 4 and the sealing member 6 . Using a Suture wire 12 or braided suture for the elongate member 4 gives a safer sealing since the suture wire comprises a number of circulating fibres thus giving the wire a rough surface with a high frictional sealing power towards a glossy surface inside the opening 14 of the second sealing member 6 .
The suture wire also makes the sealing device safer in another way. The suture wire is made in one piece and has very high tensile strength. It constitutes a continuous wire from the inner seal through the outer seal and to a tampering grip of the insertion tool, being threaded in through the first opening 8 and out again through the second opening 10 and thus keeping the sealing device safe together. If a first sealing member and an elongated member are cast in one piece there is often problem with the casting process, giving the casted member air bubbles and inclusions and accordingly giving the sealing device poor structural strength. The challenge is to make the suture wire 12 thicker in the distal lock portion 16 .
In the first embodiment of the present invention, a hollow core of the suture wire sheath is filled with a less flexible filament core 18 ( FIG. 5 ), within the area of the distal lock portion 16 of the elongate member 4 , but also in the area which is to be threaded through the first sealing member 2 . (See again FIG. 1 ). The elongated core 18 is preferably made of an absorbable copolymer in accordance with the present invention. This gives the suture wire 12 a thickening in the distal lock portion 16 .
In a second embodiment of the present invention, shown in FIG. 6 , the suture wire 12 is left unfilled within the area ranging from the entry of the first opening 8 of the first sealing member 2 , through the first sealing member 2 , out on the on the other side and in again through the second opening 10 of the first sealing member 2 to the exit of said second opening 10 .
In a third embodiment of the present invention, shown in FIG. 7 , the thickening of the first suture, of the two sutures making a pair of sutures, extends beyond the distal lock portion 16 into the proximal portion of the elongated member 4 . This gives the suture wire 12 a more continuous increasing of the thickness which simplifies the threading of the second sealing member 6 from the proximal portion onto the distal lock portion 16 .
In a fourth embodiment of the present invention, instead of being filled, the suture 12 is thicker woven in the area of the distal lock portion.
In a fifth embodiment of the present invention, ( FIGS. 8 and 9 ) the second sealing member is divided into two parts, which first part 41 is a plate and is provided with an opening that is approximately the same or slightly grater than thickness of the distal lock portion 16 . This first part 41 is threadable onto and along the elongate member 4 ( FIG. 8 ), over the distal lock portion until it is in contact with the outside of the vessel wall. The first part plate 41 is preferably quite thin, which makes it flexible and easy to adapt to the vessel wall. The second part 42 is provided with an opening that is slightly smaller than the thickness of the distal lock portion 16 . This second part 42 is threadable onto and along the elongate member 4 ( FIG. 8 ), over the distal lock portion until it is in contact with the first part 41 . The second part 42 allows for frictional engagement between the inside of the opening of the second part 42 and the distal portion 16 ( FIG. 9 ). The second part 42 is preferably thicker than the first part 41 , which will give it a large surface inside its opening for said frictional engagement. On the other hand, the diameter of the second part 42 is preferably smaller than that of the first part 41 .
In a sixth embodiment, the elongated portion 4 is not a suture wire, but another material, e.g. a resorbable polymer. The distal lock portion 16 is coated by a hollow, stocking-like suture wire so that a decent frictional engagement can be achieved between said coated distal lock portion and the inside of the opening of the second sealing member.
As mentioned above, the subject copolymers may be converted to a highly compliant, expandable tubular mantle, sleeve or cover that is placed tightly outside an expandable metallic or polymeric stent so that under concentric irreversible expansion at the desired site of a treated biological conduit, such as blood vessel or a urethra, both components will simultaneously expand and the mantle provides a barrier between the inner wall of the conduit and the outer wall of the stent. In another aspect of this invention, the subject copolymers are used as a stretchable matrix of a fiber-reinforced cover, sleeve, or mantle for a stent, wherein the fiber reinforcement is in the form of spirally coiled yarn (with or without crimping) woven, knitted, or braided construct. FIG. 10 shows schematically a radially expandable prior art spirally coiled metal stent which is applicable in the present invention.
FIG. 11 is a longitudinal view of a stent where the metal stent 100 is completely covered by the subject copolymer 101 according to a preferred embodiment of the present invention.
FIG. 12 is a cross sectional view of the stent shown in FIG. 11 .
FIG. 13 is a longitudinal view of a stent where the outer surface is covered by the subject copolymer 101 according to another preferred embodiment of the present invention. The size of a stent depends naturally of the intended use, i.e. the dimensions of the vessel where it should be applied. Typical coronary stent dimensions may have a pre deployment outer diameter of 1.6 mm and an expanded outer diameter of 3.0 mm to 4.5 mm. The length is preferably 15 mm or 28 mm.
Although the present invention has been described in connection with the preferred embodiments, it is to be understood that modifications and variations may be utilized without departing from the principles and scope of the invention, as those skilled in the art will readily understand. Accordingly, such modifications may be practised within the scope of the following claims. Moreover, Applicants hereby disclose all subranges of all ranges disclosed herein. These subranges are also useful in carrying out the present invention.
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An absorbable crystalline, monocentric polyaxial copolymer comprising a central carbon or nitrogen atom and at least three axes, each of which includes an amorphous flexible component adjacent and originating from the central atom and a rigid, crystallizable component extending outwardly from the amorphous, flexible component is disclosed along with the use of such copolymer in medical devices which may contain a bioactive agent. The present invention also relates to a suture, stents, stent mantles and sealing devices made from the polyaxial copolymer.
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This Application claims benefit of Prov. No. 60/092,771 filed Jul. 14, 1998.
BACKGROUND OF THE INVENTION
This invention relates to sample analysis systems and more particularly to a novel read head for a luminometer employed in a sample analysis system, which read head permits easy installation and removal of an analytical line of the sample analysis system.
Automated sample analysis systems such as disclosed in U.S. Pat. Nos. 5,268,167 and 5,399,497 perform a variety of different tests on a test subject, such as a serum sample, in a relatively short period of time. The serum used in the disclosed sample analysis systems is divided into a series of sample segments that move through a transparent analytical line for analysis. Consecutive sample segments in the analytical line are segregated from each other by air spaces as described in U.S. Pat. No. 4,121,466.
One aspect of sample analysis includes providing respective sample segments with different reagents to produce reactions with analytes in the serum. These reactions are the basis for a battery of test information relating to the characteristics of the serum sample. During sample analysis the reaction between an analyte in a test sample segment and a reagent produces relatively low levels of light known as chemiluminescence.
A luminometer employs chemiluminescence to identify and quantify an analyte in a test sample segment. One type of luminometer as disclosed in U.S. Pat. No. 5,714,388 includes an apparatus for collecting and transmitting chemiluminescence. The disclosed collecting and transmitting apparatus includes a read head with a core that supports optic fibers at their free ends to form a central passageway of the core. A transparent analytical line, which houses moving test sample segments, extends through the central passageway of the core. When reacting segments in the analytical line move through the central passageway of the core, the chemiluminescence from such segments is transmitted through the transparent wall of the analytical line to the ends of the optic fibers in the core for detection and analysis at other portions of the luminometer.
Occasionally the analytical line, which can be several meters long, must be removed from the read head to permit repair or replacement of the read head or the analytical line. Line removal is typically accomplished by snaking the analytical line through the central passageway of the read head core, which can be a tedious, time consuming and expensive operation.
It is thus desirable to provide a read head for a luminometer which permits removal of an analytical line from the read head without the need to snake the analytical line through the read head. It is also desirable to provide a read head that can be easily opened and closed to permit quick and simple installation and removal of an analytical line.
OBJECTS AND SUMMARY OF THE INVENTION
Among the several objects of the invention may be noted the provision of a novel read head, a novel read head including a housing and a core that permits easy installation and removal of an analytical line, a novel read head with a through opening that can be split to facilitate removal of an analytical line, a novel read head including a housing in two sections, a novel read head with a core in two half sections that are respectively secured to two sections of a read head housing, a novel read head wherein two sections of a housing and two sections of a core are convergeable toward each other to a closed position to secure an analytical line and are divergeable away from each other to an open position to permit removal or installation of an analytical line, and a novel read head with an actuator to actuate simultaneous converging movement or diverging movement of two housing sections and two core sections to permit installation and removal of an analytical line from the read head.
Other objects and features of the invention will be in part apparent and in part pointed out hereinafter.
In accordance with the invention, a read head for a luminometer includes a housing that encloses a cylindrical core. The housing has a through opening that aligns with a central passageway of the cylindrical core.
The housing is composed of a pair of housing portions pivotally joined together at a pivot member to permit converging and diverging movement of the housing portions about the pivot member. The housing portions are thus divergeable away from each other a predetermined amount to a predetermined open position and convergeable from the open position to a closed limit position.
The through opening in the housing is sized to confine an elongated analytical line, preferably formed of a flexible transparent plastic material. Serum segments that are being tested in a sample analysis system move within the analytical line through the read head.
Sections of the through opening in the read head housing are located in each housing portion. Thus when the housing portions are diverged to the predetermined open position the through opening splits into two spaced through opening sections. The analytical line can then be installed (dropped in) or removed (lifted out) from the two spaced through opening sections in a direction perpendicular to the direction of a longitudinal axis of the through opening.
Each of the housing portions are in the form of a hollow shell. The cylindrical core is formed in two sections with one of the core sections being mounted within one of the housing shells and the other core section being mounted within the other housing shell. The core sections define the central passageway that aligns with the through opening of the housing. The core sections are in a closed limit position when the housing portions are in their closed limit position. The central passageway of the core and the through opening of the housing thus confine and secure an analytical line therein when the housing portions are in the closed limit position.
The core sections are also divergeable away from each other when the housing portions are diverged from each other. Each of the core sections includes a section of the central passageway such that divergence of the core sections splits the central passageway into two spaced passageway sections. When the housing portions and the core sections are in their diverged open position the analytical line can be installed in or removed from the two spaced passageway sections of the core and the two spaced through opening sections of the housing in a direction that is perpendicular to the direction of the longitudinal axis.
In a preferred embodiment of the invention the pivot member is also supported on a support member outside the housing such that the housing portions are convergeable and divergeable relative to the support member. Actuator means are provided on the support member and the housing for actuating simultaneous converging movement or diverging movement of the housing portions relative to the support member.
The actuating means includes a moving means engageable with the housing portions for simultaneously converging or diverging the housing portions, and an actuator member for actuating movement of the moving means. The moving means include a pair of motion transfer members, with one of the motion transfer members being fixed to one of the housing portions and the other motion transfer member being fixed to the other housing portion. The moving means further include a moving member that is movable in opposite directions with respect to the housing portions, such as upwardly and downwardly with respect to the housing portions. The moving member is engageable with the motion transfer members such that movement of the moving member causes simultaneous movement of each of the motion transfer members and corresponding converging or diverging movement of the housing portions in response to the direction of movement of the moving member.
In a preferred embodiment of the invention the motion transfer members include a pin projecting from each of the housing portions and the moving member includes a bar with a horizontal slot formed at each end of the bar to permit sliding engagement of the bar relative to the pins. Thus movement of the bar in opposite directions upwardly and downwardly against the pins causes converging or diverging movement of the housing portions in response to the direction of movement of the bar.
The actuator member in the preferred embodiment of the invention includes a captive screw having one end held captive relative to the housing portions while being threadably engaged in the moving member. Thus rotation of the captive screw in one direction causes vertical movement of the moving member in one direction and reverse rotation of the captive screw causes vertical movement of the moving member in the opposite direction.
The actuating means further include a stabilizing member that is immovable with respect to the housing portion and extends through the moving member such that the moving member is movable in a vertical direction relative to the stabilizing member. In a preferred embodiment of the invention the stabilizing member is in the form of a vertical pin or rod that guides and stabilizes the vertical movement of the moving member by the captive screw.
The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the claims.
DESCRIPTION OF THE DRAWINGS
In the accompanying drawings,
FIG. 1 is a simplified perspective view of a read head for a luminometer incorporating the present invention, the read head being shown with associated fiber optic ribbon conduits;
FIG. 2 is an enlarged perspective view of the read head in a closed position and with an analytical line installed therein;
FIG. 3 is a view similar to FIG. 2 with the read head in an open position permitting installation and or removal of the analytical line;
FIG. 4 is a top view thereof with the analytical line omitted;
FIG. 5 is a sectional view thereof taken on the line 5 — 5 of FIG. 4;
FIG. 6 is a sectional view thereof taken on the line 6 — 6 of FIG. 5;
FIG. 7 is a perspective view of housing portions of the read head with a cover plate of one housing portion shown in phantom outline;
FIG. 8 is a simplified perspective view of core sections of the read head including associated fiber optic ribbons that merge into respective conduit sections;
FIGS. 9 and 10 are front views of the respective housing portions shown in FIG. 7;
FIG. 11 is a simplified perspective view of the read head in a closed position with the cover plate of one housing portion omitted and the other housing portion being shown in phantom outline;
FIG. 12 is a sectional view of the read head core in a closed position to define the central passageway for the analytical line and including the fiber optic ribbons; and,
FIG. 13 is an enlarged fragmentary detail of the central portion of the read core in closed position with the analytical line shown in section in the central passageway.
Corresponding reference numbers indicate corresponding parts throughout the several views of the drawings.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, a read head incorporating one embodiment of the invention is generally indicated by the reference number 10 in FIG. 1 .
The read head 10 includes a light proof opaque housing 18 (FIG. 1) having a through opening 19 to confine an analytical line 20 (FIG. 2 ). The housing 18 also includes a hollow space 28 (FIG. 5) for accommodation of a generally cylindrical core 34 . The housing 18 is composed of housing portions 24 and 26 (FIGS. 2 and 3) of identical construction and preferably formed of blackened anodized aluminum. Each of the housing portions 24 and 26 include a one-piece molded chamber section 25 (FIG. 7) and a cover plate 44 (FIGS. 3 and 6 ). FIGS. 7, 9 and 10 indicate the housing portion reference numbers 24 and 26 associated with the respective chamber sections 25 , 25 .
The chamber sections 25 , 25 (FIG. 7) each include fastener openings 40 and 42 for core securement, fastener openings 46 and 48 for cover plate securement, fastener openings 47 and 49 for conduit securement, and a pin receiving opening 51 for pin attachment. Corresponding aligned openings as shown in FIG. 6 are provided in each cover plate 44 .
The core 34 has a central passageway 35 (FIGS. 5 and 6) that aligns with the housing through opening 19 . The core 34 is composed of two semi-cylindrical core sections 30 and 32 (FIGS. 5 and 8) that have threaded openings 31 and 33 . The core sections 30 and 32 are respectively installed in semi-circular depressions, 38 , 38 , (FIG. 7) formed in a wall 39 of each chamber section 25 . Fasteners 55 and 57 (FIGS. 3 and 6) pass through the openings 40 and 42 in each chamber section 25 , the corresponding aligned fastener openings in the cover plate 44 and the core openings 31 and 33 to secure the respective core sections 30 and 32 to the respective housing portions 24 and 26 .
The cover plate 44 is further secured to the each of the chamber sections 25 , 25 by fasteners 43 and 45 (FIG. 3) that engage the openings 46 and 48 (FIG. 7) in the chamber sections 25 , 25 . Corresponding fasteners 43 and 45 can also be provided in the openings 46 and 48 at the wall 39 of the chamber sections 25 , 25 .
The semi-cylindrical core sections 30 and 32 include angular segments 104 (FIGS. 11, 12 and 13 ) and fiber optic ribbons 106 sandwiched between adjacent angular segments 104 . The fiber optic ribbons 106 extend from the central passageway 35 and beyond the periphery of the core sections 30 , 32 to form fiber optic bundles that are housed in fiber optic ribbon conduits 12 and 14 . The fiber optic ribbon conduits 12 and 14 extend from opposite ends of the housing 18 to transfer light produced by sample reactions in the analytical line 20 (FIGS. 2, 3 and 13 ) to a light measuring device (not shown). U.S. Pat. No. 5,714,388 discloses the construction details of a cylindrical core, and the teachings of U.S. Pat. No. 5,714,388, incorporated by reference herein, are adaptable to the construction of the semi-cylindrical core sections 30 and 32 of the core 34 .
The core sections 30 and 32 are installed in the housing portions 24 and 26 , and the housing portions 24 and 26 are mounted on a pivot rod 50 (FIG. 6 ). The pivot rod 50 passes through pivot rod openings 53 , 53 (FIG. 6) formed in pivot hinge portions 52 (FIG. 7) on each chamber section 25 , 25 . There is no corresponding pivot rod opening in the cover plates 44 , 44 . Opposite end portions of the pivot rod 50 are supported in opposite wall portions 56 and 58 of a support means 59 that includes a support member or cradle member 60 . The cradle member 60 has a base portion 62 (FIG. 6) with a base flange 64 that extends from the base portion 62 .
Under this arrangement the housing portions 24 and 26 , with their respective core sections 30 and 32 , can diverge away from each other and converge toward each other about the pivot rod 50 relative to the cradle member 60 . The housing portions 24 and 26 can be locked in a closed position by a U-shaped closure plate 57 (FIGS. 2 and 3) that is slideably mounted on the housing portion 26 for movement over the housing portion 24 . A lock screw 65 threaded into an opening 61 of the housing portion 26 (FIG. 5) locks and releases the closure plate 57 . The threaded opening 61 in the housing portion 24 need not have a corresponding screw but is blocked or filled in any suitable known manner.
The housing portions 24 and 26 have confronting or parting surfaces 63 , 63 (FIGS. 3 and 7) at the chamber sections 25 , 25 and at a vertical parting or confronting edge of each cover plate 44 , as most clearly shown in FIG. 3 . The through opening 19 includes a through opening section 90 (FIGS. 3 and 7) at the confronting surface 63 of the housing portion 24 and a through opening section 88 at the confronting surface 63 of the housing portion 26 .
The core sections 30 and 32 have confronting or parting surfaces 67 , 67 (FIG. 8 ). The passageway 35 includes a passageway section 85 at the confronting surface 67 of the core section 30 , and a passageway section 86 at the confronting surface 67 of the core section 32 .
When the housing portions 24 and 26 are in the closed position (FIG. 2) the confronting surfaces 63 , 63 (FIGS. 9 and 10) of the housing portions abut against each other as most clearly shown in FIG. 5 to define a closed limit position. The confronting surfaces 67 , 67 (FIG. 8) of the core sections 30 and 32 also abut each other when the housing portions 24 and 26 are in the closed limit position. Thus the core sections 30 and 32 are also in a closed position that defines the unified cylindrical form of the core 34 when the housing portions 24 and 26 are in the closed limit position.
When the housing portions 24 and 26 are in the closed limit position and the core sections 30 and 32 are in the closed position the analytical line 20 is surrounded by the through opening 19 of the housing 18 and the central passageway 35 of the core 34 (FIG. 13 ).
The read head 10 further includes actuating means 100 on the cradle member 60 and the housing 18 . The actuating means 100 includes a balance bar or moving member 68 that is elongated in the horizontal direction as shown in FIGS. 2 and 3. The moving member 68 , includes a horizontal slot 69 at each opposite end formed to engage respective force transfer pins 70 and 72 . The force transfer pins 70 and 72 are fixed in an opening 51 , 51 of each housing portion 24 , 26 but project from only one side of the housing 18 as most clearly shown in FIG. 4 .
Thus the force transfer pins 70 and 72 respectively project from the cover plate 44 of the housing portion 24 and from the wall portion 39 of the housing portion 26 . Corresponding openings 51 , 51 in the other side of the housing 18 are filled in any suitable known manner.
The moving member 68 includes a vertical threaded opening 75 (FIG. 6) for reception of an actuator member or control rod 74 (FIG. 2) with a finger gripping portion 73 at an upper free end of the rod 74 and an opposite end portion 78 . The control rod 74 (FIG. 6) also has a threaded portion 76 in the threaded opening 75 of the moving member 68 , with the end portion 78 being held captive in a recess 80 of the base flange 64 .
The moving member 68 is provided with a stabilizing pin 82 alongside and parallel to the control rod 74 (FIG. 2 ). The stabilizing pin 82 has one end fixed to the base flange 64 and extends vertically through an opening 83 in the moving member 68 such that the moving member 68 is slideable in a vertical direction with respect to the stabilizing pin 82 .
Under this arrangement rotation of the control rod 74 at the finger gripping portion 73 can raise or lower the moving member 68 along a vertical path controlled by the control rod 74 and the stabilizing pin 82 .
The read head 10 is thus adjustable to permit drop-in installation or lift-out removal of the analytical line 20 . To permit adjustment of the read head 10 to an open position that permits installation or removal of the analytical line 20 the closure plate 57 (FIGS. 2 and 3) is first loosened by loosening the lock screw 65 . The closure plate 57 is then slid from the locked position of FIG. 2 to the unlocked position of FIG. 3 . The control rod 74 is turned in a direction that raises the moving member 68 . The rising moving member 68 exerts an upward force on the force transfer pins 70 and 72 , which function as motion transfer members, to cause the housing portions 24 and 26 to diverge about the pivot rod 50 relative to the cradle member 60 .
Divergence of the housing sections 24 and 26 splits the through opening 19 into the two semi-circular through opening sections 88 and 90 that become spaced from each other (FIGS. 2 and 3 ). Divergence of the housing portions 24 and 26 also diverges the core sections 30 and 32 thereby splitting the central passageway 35 into the two semi-cylindrical passageway sections 85 and 86 (FIG. 8) that become spaced from each other. The analytical line 20 can thus be easily dropped into or lifted away from the split sections 88 , 90 of the through opening 19 and the split sections 85 , 86 of the central passageway 35 (FIG. 6 ).
Lift-away removal or drop-in installation of the analytical line 20 is in a direction perpendicular to the direction of the longitudinal axis of the through opening 19 . The longitudinal axis of the through opening 19 extends in the same direction as the analytical line 20 when the analytical line 20 is confined in the housing 18 and the core 34 .
While the precise dimensions of the analytical line 20 , the through opening 19 of the housing 18 , and the central passageway 35 of the core 34 can vary depending upon the outside diameter of the analytical line 20 an example of suitable dimensions for these structures and structural features include an outside diameter of approximately 2.870 millimeters for the analytical line 20 , a diameter of approximately 3.0 millimeters for the through opening 19 of the housing 18 and a diameter of approximately 3.4 millimeters for the central passageway 35 of the core 34 .
Light proofjunction members such as 91 (FIGS. 2 and 3) are provided at the housing sections 24 and 26 where the conduits 12 and 14 exit from such housing sections. The junction members 91 , 91 include a tubular support 92 (FIG. 5) for the conduits 12 and 14 combined with a plate or baffle member 94 (FIG. 8) having threaded openings 93 and 95 . The threaded openings 93 and 95 align with the openings 47 and 49 in the chamber sections 25 , 25 and the corresponding aligned openings in each cover plate 44 . The junction members 91 , 91 are held in place by fasteners 96 and 97 (FIGS. 2 and 3) that pass through the openings 47 and 49 to engage the openings 93 and 95 of the baffle member.
Some advantages of the present invention evident from the foregoing description include a read head for a luminometer that can be easily opened and closed to permit drop-in installation and lift-away removal of an analytical line from the read head, a read head that can be easily opened and closed by simply turning or adjusting a single adjustment member, and a read head that permits simple installation of a core with associated fiber optic conduits. Further advantages are a read head housing that is simply constructed of two different parts, namely, the chamber section 25 and the cover plate 44 , which are assembled to form each of the housing portions 24 and 26 . A further advantage is that the read head can be easily assembled and disassembled, and easily opened and closed without the need for special skills or extensive training.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.
As various changes can be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
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The read head for luminometer includes a housing that encloses a cylindrical core. The housing has a through opening that aligns with a central passageway of the cylindrical core to define a confinement space. The housing and the cylindrical core are formed in two parts that diverge or converge with respect to each other under the influence of a manually controlled actuator member. When the housing parts and the core parts are in a closed convergent position an analytical line that extends through the housing and the core is maintained in a confined position within the confinement space of the housing and the core. Actuation of the housing parts and the core parts into a diverged open position opens the confinement space that accommodates the analytical line. The analytical line can thus be lifted away from the previous confinement space or reinstalled back into the open confinement space and then locked in place by an actuation of the housing parts into a closed converged position along with the core parts. Installation or removal of the analytical line from the read head is thus accomplished in a direction that is perpendicular to the direction of the longitudinal axis of the confinement space.
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This is a continuation of co-pending application Ser. No. 06/895,648 filed on Aug. 12, 1986, now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to the fields of textile manufacturing, processes for shaping or treating plastic articles, textile spinning, twisting, and twining and textiles, fluid treating apparatus.
With respect to the field of textile manufacturing, the present invention is related to the areas of: (a) thread finishing by diverse finishing operations; (b) thread finishing by texturing (e.g. crimping) in which there is a control means responsive to a sensed condition; (c) thread finishing utilizing diverse texturing operations; (d) thread finishing via fluid jet having orthogonally arranged flow paths; (e) thread finishing via fluid jet having opposed reasonance chambers; (f) thread finishing via fluid jet having opposed fluid passageways.
With respect to processes for shaping or treating plastic articles, the present invention is related to the areas of: (g) processes involving twining, plying or braiding or textile fabric formation; (h) processes involving the formation of continuous or indefinite length work; (i) shaping filaments by extrusions.
With respect to textile spinning, twisting and twining, the present invention is related to the areas of (j) the strand structure of multifilament yarns wherein the filaments are crimped or bulked; (k) jet interlacing or intermingling of filaments.
With respect to the field of textiles, fluid treating apparatus, the present invention is related to the area of gas, steam, or mist treatment with continuous textile feed and discharge.
2. Description of the Prior Art
Many prior art patents are related to the process of the present invention. The closest patent is believed to be U.S. Pat. No. 4,505,013. Other patents of interest include the following U.S. Pat. Nos. 4,355,592; 4,222,223; 3,010,270; 4,343,146; 3,953,962; 3,898,719; 3,874,045; 3,874,044; 3,811,263; 3,251,181. None of these prior art patents are believed to enable the process of the present invention. The present invention enables the continuous, high speed production of a highly and uniformly entangled multifilament carpet yarn. The prior art does not provide any means for achieving a degree and uniformity of entanglement at the process speeds of the present invention.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed towards a continuous, integrated, high speed process for making a multifilament carpet yarn having a very high degree of filament intermixture. The process comprises the steps of:
(a) forwarding an undrawn multifilament carpet yarn;
(b) drawing the yarn until the elongation of the filaments has been reduced to an acceptable level for end use in carpeting applications, the drawn yarn having a denier between 2000 and 4000, the drawn filaments each having a denier between 18 and 35;
(c) crimping the drawn filaments with a jet crimping means;
(d) over-feeding the yarn to an intermixing jet, the degree of over-feeding being between 1% and 10%;
(e) intermixing the drawn, textured yarn in the intermixing jet, the intermixing jet creating a degree of entanglement of the filaments whereby a standard deviation of less than 6.0 results upon conducting a Standard Yarn Streak Potential Test; and
(f) taking up the textured, interlaced yarn at a speed of at least 800 meters per minute.
The present invention is most particularly concerned with intermixing the filaments to a very high degree. "Intermixing", as used herein is to be contrasted with entangling, interlacing and texturing. Interlacing is used to slightly entangle filaments together, so that the interlaced multifilament yarn will undergo subsequent processing with reduced flaring and individual filament wrapping. Texturing is a term used to describe mechanical deformation of filaments in order to form a textured (i.e. "crimped") filament. Both texturing and interlacing can be performed in conjunction with high speed yarn processing by using fluid jets. However, neither texturing nor interlacing creates a high degree of filament entanglement. Entangling, on the other hand, is generally utilized to create a degree of filament entanglement which is equivalent in degree to the amount of filament entanglement created by the "intermixing" process of the present invention. However, entanglement processes of the prior art have been notoriously slow, because it has never (heretofore) been possible to achieve an exceedingly high degree of filament entanglement at yarn take-up speeds in excess of about 800 meters per minute. Thus, the term "intermixing", as used herein, is defined to include only processes which enable (1) a degree of entanglement which yields a standard deviation of less than 6.0 when measured by a Standard Yarn Streak Potential Test described below while (2) the take-up speed is greater than 800 meters per minute. It has been surprisingly found that such a process is possible, and to-date the only known way of carrying out such a process is to use both supersonic steam impact on the traveling yarn along with a particular fluid jet design which will efficiently and continuously entangle the filaments to a degree which renders a standard deviation of less than 6.0 upon conducting a Standard Yarn Streak Potential Test. The process provides an additional advantage of enabling a high speed method for producing a carpet yarn which has very good tip definition in comparison with prior art carpet yarns which were made at take-up speeds below 800 meters per minute.
It is an object of the present invention to provide a high speed, one-step process for intermixing the filaments of a bulked continuous filament carpet yarn.
It is a further object of the present invention to enable the high speed production of a multicolored carpet yarn having a low streak potential as measured by the Standard Yarn Streak Potential Test as defined herein.
It is a further object of the present invention to improve the degree of filament entanglement for processes having take-up speeds above 800 meters per minute.
It is a further object of the present invention to enable, at speeds greater than 800 meters per minute, the production of a bulked continuous filament yarn having a woolish look and texture.
It is a further object of the present invention to eliminate the need for commercial processes to have a plying step necessary in the production of low-streak bulked continuous filament carpet yarns.
It is a further object of the present invention to produce a bulked continuous filament carpet yarn having filaments which are entangled along their entire length rather than at nodal points.
It is a further object of the present invention to combine a plurality of yarns having different coloration potentials, while creating a product which is made both at high speed and with a low streak potential.
It is a further object of the present invention to utilize steam at supersonic speeds in order to achieve intermixing of the filaments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic of a process of the present invention.
FIG. 2 is a schematic of an alternative process of the present invention.
FIG. 3 is a schematic of yet another alternative process of the present invention.
FIG. 4A is a longitudinal cross-sectional view of a high speed jet entangling insert of the present invention.
FIG. 4B is an exploded perspective view of the jet intermixing insert and its housing and fluid supply.
FIG. 4C is a perspective cut-away view of the insert installed in the housing, together with a simulation of a yarn traveling through the intermixing insert.
FIG. 5 is another alternative process of the present invention
FIG. 6A illustrates an untrafficed carpet made without the advantages of the present invention, while FIG. 6B illustrates the carpet of FIG. 6A after trafficking.
FIG. 7A illustrates an untrafficked carpet made with the advantages of the present invention, while FIG. 7B illustrates the carpet of FIG. 7A after trafficking.
FIG. 8 depicts a carpet yarn process in which two primary yarns are co-spun.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates, in schematic form, the process of the present invention. An undrawn feed yarn (1) is taken off of a package (2), fed through a first guide (3) and makes about 3 wraps around a first godet (4). The first godet (4) is used to pretension the yarn. The yarn is then drawn between a second godet (5) and a third godet (6). The yarn makes 7 or 8 wraps around both the second godet (5) and the third godet (6). The yarn (1), now drawn, is then texturized in a texturizing tube (7). This texturizing tube is described in U.S. Pat. Nos. 3,908,248 and 3,714,686, which are hereby incorporated by reference. The now texturized yarn (1) then travels over a direction changing roll (8) and a tensioning device (9) after which the yarn contacts a fourth godet (10) and a fifth godet (12). The texturized yarn is over-fed from the fourth godet (10) to the fifth godet (12). Between these godets (10 and 12) is an intermixing jet (11). After exiting the fifth godet the yarn (1) passes over another direction changing roller (13) and onto the traverse roll (16) of a winder (14). A yarn package (18) is then built up upon a package tube (not shown), the package (18) being driven by a friction roll (15). A second package tube is to be rotated into contact with the friction roll (15) after a full package (18) is built up upon tube.
FIG. 3 illustrates a schematic of a preferred process of the present invention. In this process, eight (only four packages (2) are shown) primary, feed-yarns (1), held on packages (2), are each threaded through individual guides 3. All eight of these primary feed-yarns (1) are then passed through a second guide (19) and a preinterlacer (20), and are then fed to the pretensioning godet (4). The primary yarns (1) are then drawn between the second godet (5) and the third godet (6), and the drawn yarns (1) are then texturized in the texturizing tube. After passing over direction changing rolls 8 and 9, the yarns (1) pass around the fourth godet (10). An additional yarn (25) herein termed an "accent yarn" is merged into the drawn, texturized yarns (1) on the fourth godet (10). The accent yarn is preferably also solution dyed (i.e. pigmented). The accent yarn (25) is supplied from a package (26), the accent yarn passing through two guides (27 and 28) before going onto the fourth godet (10). Upon exiting the fourth godet (10), the yarns (1 and 25) are intermixed in the entangling jet (11). The yarns are over-fed to the intermixing jet (11) by having the surface speed of the fourth godet (10) higher than the surface speed of the fifth godet (12). The yarns (1 and 25) then pass over a direction changing guides (13) and onto winder 14, and are wound to form package 18, as described above.
FIGS. 4A, 4B, and 4C show detailed views of the intermixing jet (11) which is utilized to intermix the filaments in the process of the present invention. The intermixing jet (11) is comprised of an insert housing (29) having an insert (30) which is positioned therein. The flow of steam is partially confined by O-rings 31 and 32, these O-rings forcing the steam to travel through a slit (33) in the insert (30), i.e., the O-rings 31 and 32 preventing the steam from escaping between the housing (29) and the insert (30). The insert (30) is locked into place with a setscrew (34), and steam is supplied to the housing via an opening (not shown) to which is attached a threaded connector (35). The slit (33) in the insert (30) is approximately 1.4 millimeters wide, and preferably extends approximately 180 degrees around the circumference of the insert. As a result of the shape of the slit (33), the yarn traveling through the intermixing jet (11) cannot escape continuous impingement of supersonic steam which is entering the yarn-impact chamber 36 via slit 33. The shape of the slit (33) creates an inescapable flow of steam. It is believed that this inescapable flow is largely responsible for the "continuous intermixing" (to be distinguished from "nodal entanglement") produced by the present invention. Nodal entanglement creates spaced regions of high filament entanglement between which are regions virtually free of filament entanglement. The "continuous intermixing" form of entanglement produced by the process of the present invention contrasts with nodal entanglement in that the filaments are entangled along the entire length of the yarn, there being no regions without a fairly high degree of filament entanglement.
The process of the present invention is "continuous" in time. That is, the process carries out drawing, texturizing, and intermixing all at once. In contrast, commercial prior are processes have utilized a separate and expensive plying step in order to create a carpet yarn which had a low streak potential, as measured by the test described below.
The process of the present invention is "intergrated" in that the steps of drawing, texturizing, and intermixing are carried out in a single operation rather than as separate operations which require separate yarn winding steps. Prior art commercial processes which utilizing plying to create a low streak-potential product also require an additional winding step, which increases manual handling, energy consumption, and costs.
The process of the present invention is "high speed" in that the yarn must be taken up at a speed of at least 800 meters per minute. Prior art processes which have produced a jet-entangled yarn having a streak-potential as low as that of the present invention have operated at significantly lower speeds--i.e., below 800 meters per minute and generally between 100 and 500 meters per minute. This is because the prior art has not had the means to create a high degree of continuous filament intermixing at a high speed.
"Crimping " has been defined above as mechanical deformation of filaments in order to form a texturized filament. Although the crimping may be carried out in a variety of manners, it is most preferable that the process utilize the crimping tubes taught in U.S. Pat. Nos. 3,908,248 or 3,714,686.
The process illustrated in FIG. 1 can be carried out with an uncolored, dyeable feed yarn, with a dyed feed yarn, or with a precolored (pigmented) feed yarn. The high degree of intermixing (for a yarn of only a single color) provides the advantage of producing, at high speed, a yarn which will show delayed "ugly-out" when made into a cut pile carpet. "Ugly-out" is a term used to describe the loss of tip definition caused by heavy traffic on the carpet. Heavy traffic causes the filaments of each yarn to flair out, causing a "mushy" and "indistinct" look which is undesirable. It has been found that the intermixed yarn, when made by the process described herein, tolerated more traffic while exhibiting less ugly-out than carpets made from carpet yarns which had been entangled to a lesser degree.
The process of the present invention is advantageously carried out as shown in FIG. 2. The greatest assets of the present invention lie in its advantages for combining yarns which have significantly different coloration potentials. The high degree of entanglement of textured yarns produces a yarn which not only exhibits delayed ugly-out, but also has fewer streaks than prior art carpet yarns produced at similar speeds without a plying step. Streaking is always a problem with bulk continuous filament carpet yarn comprising filaments of substantially different coloration, and it has long been the practice to ply two yarns together in order to reduce the potential for streaking to result. The plying operation is an additional step and is time consuming and expensive. The process shown in FIG. 2 may utilize, for example, one white (undyed) polyamide primary feed yarn (1) which is acid dyeable, one black (pigmented) polyamide tonal primary feed yarn (21) and a fully drawn, untextured, red (pigmented) accent yarn (25). The combined yarns, once wound onto the package (18), will appear as a grey yarn (tonal yarn mixed evenly with the white feed yarns) along with a red accent yarn which stays bundled together (i.e. is not intermixed). In a carpet made from this yarn, if the white yarn was left undyed the carpet would appear to have a grey base and a red "berber" effect. The grey is created by the high degree of mixing of black and white filaments and the red "berber" effect is created by the lack of mixing of the red filaments with either the black or white filaments. The entangling jet (11) has been found to effectively intermix only the crimped filaments. The untextured filaments of the accent yarn (25) are not intermixed by the entangling device (11). Rather, these filaments remain relatively intact as a bundle. It has been theorized that it is the excessive length (i.e., potential slack) present in crimped yarns together with the fullness (i.e., low density) present in crimped yarns which allows the impact of a fluid stream to create a greater degree of filament entanglement than with uncrimped yarns.
The present invention is most useful in the manufacture of bulked continuous filament carpet yarns which, when drawn, have a denier between 2000 and 4000, the drawn filaments each having a denier between 18 and 35.
The present invention pertains to a process which intermixes drawn, textured filaments in the intermixing jet, the intermixing jet creating a degree of intermixing of the filaments whereby a standard deviation of less than 6.0 results upon conducting a Standard Yarn Streak Potential Test. The Standard Yarn Streak Potential Test is conducted as follows:
Two primary feed yarns are drawn, textured, intermixed, and wound onto a package. One of the feed-yarns is a 9100 denier (before drawing), 135 filament semi-dull bulked continuous filament white yarn. The other feed yarn is a 2625 denier (before drawing) 42 filament black bulked continuous filament feed-yarn. The resulting drawn (by a factor of 3.2×), textured, intermixed, wound product is used to make a 0.1 guage, level loop, 28 ounce/square yard carpet having a pile height of 3/16 inch. The carpet is tested by making colorimetric measurements with the Small Angle View attachment on a Macbeth 1500 colorimeter at between 65 and 100 different locations on the carpet. The Macbeth 1500 colorimeter analyzed an area of approximately 2 cm×1 cm, this area being oriented in the direction of tufting (i.e., along the length of the yarn). The values obtained were averaged to establish a standard reference point. Then another 35 to 50 additional measurements were made and compared against the standard reference point. The DL's were recorded, from which a standard deviation was calculated. The standard deviation is a quantitative measurement of the degree of color mixing obtained in the sample. It should be emphasized that the Standard Yarn Streak Potential Test requires that: (1) the yarns used are: (a) a drawn and textured 2600 denier/135 filament semi-dull white yarn, and (b) a 750 denier/42 filament black yarn; and (c) that the standard reference point and the 35 to 50 additional measurements are made on the same type of carpet as described above and that the measurements are taken in the same manner as described above.
The Standard Yarn Streak Potential Test can be carried out in order to determine whether any process which draws, texturizes, and intermixes via fluid jet will create a product having a standard deviation of less than 6.0. One must simply substitute the feed-yarns (described above) into the process, make the carpet according to the description above, and analyze the carpet as described above. It is most preferred that the degree of intermixing is high enough so that the resulting standard deviation is less than 5.0.
It has been determined that the intermixing jet utilized in the present invention should have a yarn-impact chamber (36, as shown in FIG. 4A) diameter between 3/64 inch in diameter and 3/16 inch in diameter. It has also been found that the length to diameter ratio within the yarn-impact chamber (36) is most preferably 2.4. It has been found that an L/D of 2.0 does not result in sufficient intermixing and that an L/D of 2.8 results in a product having too much "stiffness" (i.e., a harsh hand). The slot (33) is most preferably about 0.044 inch wide and most preferably extends 180 degrees around the yarn-impact chamber, creating an "inescapable" jet of fluid to impact the yarn in the yarn-impact chamber. It has been found that the supersonic flow of steam causes the creation of filament loops when the steam impacts the yarn traveling through the intermixing device. These loops create a "wool like" appearance in the resulting product.
The process of the present invention may additionally comprise the step of extruding the primary yarns immediately prior to forwarding the primary yarns to the second godet (5). This creates the advantageous economic effect of elimination of the winding step used to make the packages (2, 22 and 26) shown in FIG. 2. In addition, although the accent yarn is generally thought to provide a desired coloration effect, one could utilize an antistatic yarn in order to impact an antistatic characteristic to the resulting product. The antistatic yarn (or the accent yarn, for that matter) could be a multifilament or a monofilament, and could be predrawn and pretextured or merely predrawn and untextured.
EXAMPLE 1
The process was carried out as shown in FIG. 2. A 6700 denier, 58 filament, undrawn nylon-6 white feed yarn (1) was fed from a package (2) through two guides (3 and 19), following which the feed yarn (1) came into contact with a pretensioning godet (4). As used herein, the term "godet" is meant to include both the large driven roll along with the smaller "idler" roll. When the yarn is described as being "wrapped around the godet", it is, of course, meant that the yarn is wrapped around the driven roll and the idler roll as a pair, rather than being wrapped more than 1 full circumference around any single roll.
A 726 denier, 14 filament, undrawn (approximately 460% elongation to break), nylon-6, black "tonal" yarn (21) was taken from a second package (22), this yarn also passing through two guides (23 and 24) before merging into the white yarn (1) on the pretensioning godet (4). After making three wraps on the pretensioning godet, the combined feed and tonal yarns (1 and 21) made seven wraps around a second godet (5). The second godet (5) was maintained at a temperature of approximately 50° C. The surface speed of the second godet (5) was 372 meters per minute. The yarns (1 and 21) then made seven wraps around a third godet (6) having a surface speed of 1200 meters per minute and a temperature of 160° C. Of course, the yarns (1 and 21) were drawn approximately 3.2× between the godet (5) and the third godet (6). Upon contacting the third godet (6), an antistatic yarn (40), supplied from a yarn package (41) was merged into contact with the now drawn yarns (1 and 21). The antistatic yarn (40), the feed yarn (1), and the tonal yarn (21) were then texturized in a texturizing tube (42) similar to those described in U.S. Pat. No. 3,908,248 and U.S. Pat. No. 3,714,686. The texturizing tube was supplied with hot air (450° C.) at a pressure of 85 psi (source of hot air not shown). After texturing, the combined feed yarn (1), tonal yarn (21), and antistatic yarn (40) were passed partially around a direction changing roll (8) and then around a tensioning device (9), and finally around a fourth godet (10). The surface speed of the fourth godet was 905 meters per minute. A 220 denier, 14 filament, nylon-6, red "accent" yarn (25), supplied from a package (26), was then merged into contact with the already combined and texturized yarns 1, 21 and 40. After making 5 wraps around the fourth godet (10), the now combined yarns (1, 21, 40 and 25) were passed through an intermixing jet (11). The intermixing jet had a 180 degree slit which was 0.044 inch wide, this slit being supplied with saturated steam (177° C.) at 120 psig. The intermixing jet had a yarn-impact chamber which had a length of 0.3 inch and a diameter of 0.125 inch, and the intermixing jet was proportioned as shown in FIG. 3A. The impact of the steam on the traveling yarns created a high degree of filament entanglement between the feed yarn (1) and the tonal yarn (21) and also created filament loops which protruded from the highly entangled filaments at random intervals. The accent yarn was tied into the remaining filaments, but was not intimately mixed thereinto. The now intermixed yarns (43) then made 5 wraps around a fifth godet (12). The surface speed of the fifth godet (12) was 860 meters per minute. The intermixed yarns (43) then passed around a direction changing roll (13) and were then wound to form a package (18) on a Rieter winder, Model JT/A, (14), at a speed of 864 meters per minute. The fourth and fifth godet pairs (10 and 12) were not heated, i.e. they were kept at room temperature. The yarn tension at specific points (A-G, as shown in FIG. 1) in the process was as follows:
______________________________________Designated TensionPoint in Process (Total, in Grams)______________________________________(a) 6000(b) 80(c) 10(d) 40(e) 10(f) 100(g) 140______________________________________
The resulting product was a yarn having textured, very evenly mixed white and black filaments together with a bundle of untextured, unmixed red filaments. When made into a carpet, the yarn appeared, from a distance, to be heather grey with flecks (i.e. points) of red randomly dispersed to give a berber effect. The white feed-yarn (1) could then be dyed in any of a wide variety of colors, as desired.
EXAMPLE 2
The process was carried out as shown in FIG. 1. An 1800 denier, 99 filament, undrawn, nylon-6 white feed-yarn (1) was fed from a package (2) through a guide (3) and onto a pretensioning godet (4), where the yarn was wrapped around the godet three times. The undrawn yarn had a elongation to break of approximately 460%. The yarn (1) was then wrapped seven times around a second godet (5), this second godet (5) being maintained at a temperature of 50° C. The second godet pair had a surface speed of 372 meters per minute. The yarn was then drawn between the second godet (5) and a third godet (6), which the yarn was wrapped around a total of seven times. The third godet (6) had a surface speed of 1200 meters per minute and was maintained at a temperature of 160° C. Upon exiting the third godet (6), the now drawn yarn (1) entered a texturing tube as described in Example 1. The texturizing tube was supplied with hot air (450° C.) at a pressure of 85 psi. After texturizing, the now drawn and texturized feed yarn (1) was passed partially around a direction changing roll (8) and then around a tensioning device (9), and finally around a fourth godet (10). The fourth godet (10) was not heated (i.e. was at room temperature) and was maintained at a surface speed of 880 meters per minute. After making 5 wraps around the fourth godet (10), the yarn (1) next passed through an intermixing jet (11). The intermixing jet had a 180 degree slit which was 0.044 inch wide, this slit being supplied with saturated steam (177° C.) at 120 psig. The intermixing jet (11) had a yarn-impact chamber which had a length of 0.3 inch and a diameter of 0.125 inch, and the intermixing jet was proportioned as shown in FIG. 3A. The impact of the steam on the traveling multifilament yarn created a high degree of filament entanglement and also created filament loops which protruded from the highly entangled filaments at random intervals. The yarn (1) then made 5 wraps around a fifth godet (12). The surface speed of the fifth godet (12) was 860 meters per minute. The yarn (1) then passed around a direction changing roll (13) and was then wound to form a package (18) on a Rieter Winder, Model JT/A, (14), at a speed of 875 meters per minute. The fourth and fifth godet pairs (10 and 12) were not heated, but instead were kept at room temperature. The yarn tension at specific points (A-G, as shown in FIG. 3) in the process was as follows:
______________________________________Designated Point Tensionin Process (Total, in Grams)______________________________________(a) 3000(b) 80(c) 10(d) 40(e) 10(f) 100(g) 140______________________________________
EXAMPLE 3
The process was carried out according to the schematic illustrated in FIG. 3. Eight 1089 denier, 14 filament undrawn precolored nylon-6 feed yarns (1) were feed from eight packages (2). Only four of the eight packages are shown in FIG. 3. Four of the eight yarns were brown, two yarns were beige, one yarn was orange, and one yarn was white. Each of the yarns (1) was first threaded through an individual guide (3), following which all eight yarns (1) were together threaded through a group guide (19). The feed yarns (1) were then directed through a preinterlacer (20). The preinterlacer (20) was supplied with compressed air at approximately room temperature and at a pressure of 150 psig. The preinterlacer (20) had a circular yarn throughout passageway 0.1875 inch in diameter and 0.30 inch long. The preinterlacer had three jet orifices, each of which intersected the axis of the yarn throughput orifice at an angle of 90 degrees. The axes of the three jet orifices were in a single plane and were positioned equidistantly from one another so that there was no net directional effect on the yarns being preinterlaced. Each jet orifice had a diameter of 0.0625 inch. After passing through the preinterlacer (20), the feed yarns (1) came into contact with a first (pretensioning) godet (4). After making three wraps around the first godet (4), the combined feed yarns (1) made seven wraps around a second godet (5). The second godet had a surface speed of 372 meters per minute and was heated to a temperature of 50° C. From here, the yarns (1) made ten wraps around a third godet (6), the third godet (6) having a surface speed of 1200 meters per minute and a temperature of 160° C. The yarns (1) were drawn 3.23× between the second godet (5) and the third godet (6). The yarns (1) were texturized in a texturing tube (7) similar to those described in U.S. Pat. Nos. 3,908,248 and 3,714,686. The texturizing tube was supplied with hot air (450° C.) at a pressure of 85 psi. After texturizing, the feed yarns (1) were passed partially around a direction changing roll (8) and then around a tensioning device (9), and finally made 5 wraps around a fourth godet (10). An antistatic yarn (25), supplied from a package (26), was merged with the feed yarns (1) on the fourth godet (10). The fourth godet was unheated, and had a surface speed of 905 meters per minute. The combined yarns (1, and 25) then passed through an intermixing device (11) and then made 5 wraps around a fifth godet (12) which had a surface speed of 860 meters per minute and was also unheated. From here the combined yarns (1, and 25) passed over a direction changing roll (13) and finally were taken up on a Rieter Winder, Model JT/A, (14), at a speed of 868 meters per minute. A yarn package (18) was formed by the winder (14). The yarn tension at specific points (A-G, as shown in FIG. 3) in the process was as follows:
______________________________________Designated Point Tensionin Process (Total, in Grams)______________________________________A 5000B 80C 10D 40E 10F 100G 140______________________________________
In the process described above, the intermixing jet was substantially as shown in FIGS. 3A, 3B, and 3C. The jet (11) had an 180 degree slit which was 0.044 inch wide, this slit being supplied with saturated steam (at 177° C.) at 120 psig. The jet (11) had a yarn-impact chamber which had a length of 0.3 inch and a diameter of 0.125 inch, and the intermixing jet was proportioned as shown in FIG. 3A. The product exhibited a very high degree of entanglement of the filaments, and filament loops also protruded from the resulting product.
EXAMPLE 4
This example is intended to show how the Standard Yarn Streak Potential Test may be applied to a process in order to determine the standard deviation which the process is capable of producing. A process (carried out as shown in FIG. 5) was subjected to the Standard Yarn Streak Potential Test in order to determine whether the resulting standard deviation was less than 6.0.
Two primary feed yarns (1 and 21) were drawn, textured, intermixed, and wound onto a package. The first feed yarn (1) was a 9100 denier (before drawing), 135 filament semidull (0.3 percent TiO 2 ), continuous filament, white polycaprolactam yarn. The second feed yarn (21) was a 2625 denier (before drawing), 42 filament, black continuous filament polycaprolactam feed yarn. These yarns were drawn, textured, intermixed, and taken up under the conditions described in Example 2. Thus, Example 4 is, in effect, a description for subjecting the process of Example 2 to the Standard Yarn Streak Potential Test. The resulting product was used to make a 0.1 gauge, level loop, 28 ounce per square yard carpet having a pile height of 3/16 inch. The carpet was tested by making colorimetric measurements with the Small Angle View attachment on a Macbeth 1500 colorimeter. Measurements taken by the colorimeter represented the percent of light reflected upon subjecting a portion of the carpet to a given amount of light. Measurements were taken at 50 different locations on the carpet. The Macbeth 1500 colorimeter measured an area of approximately 2 centimeters by 1 centimeter, this area being oriented in the direction of tufting (i.e. along the length of the yarn). The values obtained were averaged in order to establish a standard reference point. After calculation of the standard reference point, another 75 measurements were made, each being compared with the standard reference point. The DL's were recorded (the DL's were based on the CIELAB color order system), and a standard deviation of 5.34 was calculated.
EXAMPLE 5
This example is intended to show how the Standard Yarn Streak Potential Test may be applied to a process similar to that discussed in Example 4. The process was carried out as shown in FIG. 5 and as described above in the process description related to FIG. 5. However, in place of the intermixing device (11), a conventional interlacer was utilized. The interlacer used was exactly the same as the prenterlacer (20) utilized in FIG. 3. However, in this Example, the interlacer (2)) of FIG. 3 was used in place of the intermixing device (11) of FIG. 5. The interlacer (20) was made and operated at the same specifications described in Example 3. Again, two primary feed yarns were drawn and textured exactly as in Example 4. The feed yarns were identical to those used in Example 4. The interlacer was supplied with compressed air at 150 psig. The resulting product was used to make a carpet of the same specifications as described in Example 4. Colorimetric measurements were taken exactly as described in Example 4. A standard deviation of 9.27 resulted.
A comparison of Examples 4 and 5 illustrates the need for the use of a device which is capable of intermixing the filaments rather than interlacing the filaments. A visual examination of the carpet produced in Example 4 revealed that the carpet produced via Example 4 exhibited a "solid heather" appearance. In contrast, a visual examination of the carpet produced via Example 5 revealed that the carpet produced via Example 5 exhibited a "random stria" appearance. It has been conceived that any carpet exhibiting a standard deviation of less than 6.0 (as measured by the test) will also exhibit a "solid hether" appearance, while any carpet exhibiting a standard deviation of greater than 9.0 (again, as measured by the test) will also exhibit a "random stria" appearance. The low streaking present in the solid heather carpets is considered to be highly desirable, and has been achieved in the past using both relatively low speed processes and plying processes.
FIGS. 6A and 6B illustrate the effect of traffic on a carpet made using prior art technology. The carpet is new in FIG. 6A, while FIG. 6B illustrates the same carpet after 133,000 "traffics". FIG. 7A and 7B illustrate a carpet which is identical to the carpet of FIGS. 6A and 6B, except that the carpet shown in FIGS. 7A and 7B utilized an intermixing step in the yarn production process. FIG. 7A represents this carpet when new and FIG. 7B represents this carpet after 133,000 "traffics". A comparison of FIG. 6B with FIG. 7B illustrates the dramatic difference in tip definition after heavy trafficking. Obviously, the carpet made with the intermixed yarn FIG. 7B) was far more durable in terms of tip definition (i.e. "ugly-out") than the carpet illustrated in FIG. 6B, which was made using a prior art interlaced yarn which had 10-12 nodes per meter.
FIG. 8 depicts a process in the manner of FIG. 5, except the carpet yarns are co-spun in a single process. Primary feed yarn 101 is spun from a conventional spinning device 102. A second feed yarn 103 of different characteristics is spun from spinning device 104. The two yarns are converged through eyelet guides 3 and 19 prior to being contacted by pretensioning godet 4. The combined yarns are then drawn between godets 5 and 6, textured in device 42, intermixed in jet 11 and wound into a package 15.
The carpets shown in FIGS. 6A and 6B are velvet plush (cut loop) carpets having a pile height of 3/8 inch, and 48 oz./square yard of face yarn. The yarns used in both carpets consisted of: (a) an 1800 denier nylon-6 bulked continuous filament space dyed yarn, which was plied with (b) two ends of 2000 denier, stock dyed, nylon-6 spun yarn. The spun yarns were each made from 8 inch burgundy colored staple. Each of the spun yarns had 31/2 twists per inch, and the plying process inserted 11/2 twists per inch into the final yarn. The space dyed yarn was dyed black and brown. In the carpet shown in FIG. 5A, the 1800 denier space dyed yarn was interlaced so that it contained 10-12 nodes per meter, while in the carpet shown in FIG. 7A, the 1800 denier space dyed yarn was intermixed so that it had virtually continuous filament entanglement.
FIGS. 5A, 5B, 7A and 7B illustrate the fact that the process of the present invention is capable of making a yarn at high speed which has improved tip definition over prior art carpets which are made at high speed with entanglement via interlacing. Improved tip definition is an improvement for any carpet, i.e. both solid and multicolored carpets. The reason for using multicolored yarns in FIGS. 5A and 7A was simply for purposes of making the improved tip definition more conspicuous.
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A continuous, high speed (greater than 800 meters per minute) process and apparatus enable the production of a multifilament carpet yarn having a degree of filament intermixture high enough so that a standard deviation of less than 6.0 results upon conducting a Standard Yarn Streak Potential Test, as described herein. The apparatus and process allow the production of a multicolored carpet yarn which exhibits a reduced tendency to streak and an increased retention of tip definition.
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