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FIELD OF THE INVENTION
The present invention relates to bonding and more particularly to the preparation of two surfaces for bonding with a bonding agent.
BACKGROUND OF THE INVENTION
There are numerous methods that have been used for joining together two or more surfaces. The more common methods include welding, joining, or bonding. Two surfaces may be welded together by melting or dissolving them together. Two surfaces may be joined together using a suitable piece of strong material that can be pushed or compressed in some manner. Included in this category are bolts, screws, nails, and rivets. Two surfaces may be bonded together using a bonding agent that forms an adhesive bond to both surfaces. Pressure sensitive adhesives commonly employed for use in labels are a prime example of this type of bonding. Two surfaces may also be mechanically bonded together with a bonding agent that hardens to a strong rigid material. A good example of this bonding is the use of glue to bring two surfaces of wood together.
In the case of welding two surfaces together, if carried out properly with the right materials, very strong bonds result which can be as strong or even stronger than the two substrates themselves. The welding of two metal surfaces is accomplished by employing a small but intense area of heat at the site where the two pieces are to be joined. The heat is so intense that the metal of both pieces melts and flows together. Quite often additional metal is added to the weld during the process. A welding rod of a suitable material (usually the same material as the substrate) is placed in the heated area so that it melts and flows into the weld to build it up. Most metals require very high temperatures and as such only certain conditions are suitable for welding. These include electrical discharge for arc, tig, mig, and spot welding and high temperature gas mixtures such as acetylene-oxygen for gas welding.
Unfortunately, welding cannot always be used to bond two metal surfaces together. In many instances the substrates may not be made of a material that can be welded. In addition, even if the substrate is made of a suitable material it may not be of suitable dimensions for welding. It may be too thin making welding without bum through difficult or even impossible. One surface may be on a thicker substrate than the other resulting in uneven heating or even thermal distortion.
The welding together of two plastic surfaces requires that the plastic is capable of either melting by the application of heat, or dissolving into a solvent. In the case of joining plastic surfaces together by heat, the plastic must have a suitable melting point that allows the material to flow together. Many plastics will soften but not easily melt. In such instances it is often practice to use an alternative method to weld the two pieces together without the need to apply heat. Some plastics are soluble in common solvents. For example polystyrene is substantially soluble in toluene. If a drop of toluene is placed onto a piece of polystyrene and a second piece of polystyrene placed on top, the toluene will dissolve some polystyrene from both surfaces. This layer of polystyrene solution will mix into both surfaces. When the toluene evaporates, the pieces will be firmly joined. Sometimes it is practice to dissolve some of the plastic into the solvent prior to application between the two surfaces to be joined. The familiar plastic model kits sold in hobby shops use this system. The individual model pieces are made from polystyrene, and the glue is a solution of polystyrene dissolved in toluene. This system works well because when the two pieces are bonded together with this glue, the final joint that results is the same material as the substrate (polystyrene). In this respect a true weld has been achieved.
While effective for joining certain types of plastic materials together, welding by heat and/or solvent will not work for the stronger more advanced plastics used in composites. The reason for this is that a weld derives strength by forming a continuous bond of substantially the same material from one substrate to the other. In other words, The two pieces that are welded together literally become one. It is as if the resultant piece was initially made as a single piece. In order for this to take place, the substrate material must become fluid and flow to become at least part of the joint. Advanced polymers commonly employed in composites contain a substantial amount of crosslinking.
The crosslinking keeps the polymer rigid and strong. Crosslinking also prevents the polymer from being welded by heat or solvent. Heavily crosslinked polymers will not melt. If heated they will burn or degrade without melting. Heavily crosslinked polymers will not truly dissolve in solvents. They may swell or even become weak enough to pull apart, however they will not dissolve to form a free flowing liquid.
The joining of two pieces together using a third piece that interconnects both pieces to be joined is a very common practice. A good example of this method of joining is the common nail. A nail is a relatively long and narrow piece of metal having a sharpened end and a blunt end. When joining two pieces together using nails, one piece is placed on top of the other. The sharp end of the nail is positioned into the top piece and directed toward the bottom piece. A hammer is then used to strike the blunt end causing the nail to be driven into both pieces. The result is that the nail holds both the top piece and the bottom piece together. While common for joining two wooden boards together, nails are relatively easily pulled out. Furthermore if nails are to be used for joining two pieces of material together the material must yield to the nail without breaking or shattering. Thus while effective for joining two pieces of wood, nails are not always best suited for joining hard or brittle materials together.
Other examples of this type of fastening include rivets, bolts, and screws. Rivets are fasteners having a wide end and a narrow end that is expandable. Using rivets requires a hole to be drilled through both substrates. The holes are aligned and the rivet pressed into this hole until the wide end rests firmly against the top piece. When the rivet has been pressed all of the way in, the narrow end is expanded so that it cannot work its way out. Rivets are commonly used to join thin sheets of metal together.
Bolts and screws are threaded fasteners that can either be threaded directly into a substrate or alternatively can have a threaded nut screwed onto the free end to tighten the substrates together. In either case, these fasteners join two pieces together by virtue of the fastener itself providing an independent connection between the two pieces.
The bonding of two substrates together with a bonding agent relies on both the strength of the bonding agent as well as adhesion of the bonding agent to both joining surfaces. Adhesive bonding between a bonding agent and a surface relies on molecular attraction and compatibility between the bonding agent and the substrate. If the surface to be bonded and the bonding agent can form true chemical bonds which cross the interface between them, then a strong bond can form based on molecular attraction alone. The nature of this attraction can be that of covalent bonds that result from surface reactions between the bonding substrate and bonding agent, or alternatively, Ionic bonds may form between oppositely charged atoms or groups of atoms. Weaker attractive forces may also play a significant role in adhesion such as hydrogen bonding, polar forces or even the weak attractions that result from the electron clouds in the atoms of one molecule being weakly electrostatically attracted to the positively charged nuclei in the atoms of other molecules.
This type of bonding, while being exceedingly strong, is not easily achieved. In addition, substantial improvements can be obtained by increasing the available surface area. This is usually done by increasing the surface roughness of the substrate. With adhesive bonding the surface of the substrate in the bonding area must be absolutely clean and free from foreign contamination. Furthermore contamination must be removed on a molecular level. In practice this is exceedingly difficult to achieve. Because of this, the use of surface adhesion alone for bonding is very difficult to achieve and in practice many bonding agents rely on at least some mechanical interlocking between the bonding agent and the intended bonding surface of the substrate.
In practice, adhesive bonding by itself is rarely if ever encountered. There is usually some surface roughness which results in some mechanical interlocking of the bonding agent to the substrate. Both factors combined determine if a bonding agent will adequately fasten together two substrates. In other words adhesive bonding usually relies at least partly on mechanical bonding.
Mechanical bonding resulting from the interlocking between a bonding agent and a substrate surface naturally occurs to some extent owing to the fact that most surfaces are inherently rough. This is especially true if the surface roughness was increased for the purposes of promoting adhesion. Surface roughness enhances bonding between a bonding agent and the substrate surface by increasing the available surface area for bonding and by providing sites where mechanical interlocking of the bonding agent with the substrate can occur.
Many bonding agents such as polymers used in the composite industry tend to shrink when cured. This shrinkage can be in excess of one percent. Such shrinkage may result in the delamination or separation of the bonding agent from the substrate or cause the formation of stress that can result in delamination at a later time. In either case, the shrinkage of common curable polymer based bonding agents such as epoxy resins when cured represents substantial bonding issues.
Fillers are often mixed with bonding resins prior to curing. One particularly common filler is fumed silica. This material is a form of silicon dioxide which is very small in particle size. Because there is less resin, (some of the volume is now occupied by the inert filler) overall shrinkage is reduced. Other fillers include hollow polymeric microballons such as 410 Microlight available from West System. West system is a registered trademark of Gougen Brothers, Inc., P.O. Box 908, Bay City, Mich. 48707. Flocked cotton fiber, microscopic glass bubbles, and glass fibers cut to relatively short lengths of less than about one inch.
One particularly interesting example of the use of fillers to reduce shrinkage is outlined in U.S. Pat. No. 4,108,813. Intermeshing spherical quartz sand particles are used to reduce the shrinkage of flooring cement along with the addition of smaller spherical plastic beads to improve flow characteristics. The result is a low viscosity mixture that hardens into a dense cement floor structure with very little shrinkage.
In addition to reducing the shrinkage of curable bonding agents, many fillers increase bulk strength and often improve overall adhesion. Unfortunately, the use of fillers with curable bonding agents does not always guarantee that a strong and permanent bond will result.
The best way to assure that a strong and permanent bond will form between a bonding agent and substrate is by way of mechanical anchorage. Even in the absence of adhesive forces mechanical anchorage by a bonding agent to a surface by physical interlocking assures a good bond. In the case of the rivet, in order to separate the two pieces, the rivet must be broken. Although there are no adhesive forces between the rivet and the substrates, mechanical interlocking provides a strong bond. In a similar manner when a bonding agent is attached to a substrate by mechanical interlocking anchorage either the bonding agent or the substrate must be broken in order to achieve separation.
Ideally it is best practice to provide a strong bond between a substrate and bonding agent that has mechanical interlocking as well as good surface adhesion. A good example of this type of bonding is the use of wood glue. Wood glue is a water based polar polymer emulsion that is compatible with the surface of wood. Often these polymer emulsions contain polyvinyl alcohol as an additive or as part of the polymers that make up the glue itself. Polyvinyl acetate is also employed with many wood glues which of course is polar by virtue of the ester group of acetic acid. Hydrogen bonding and polar forces result in good adhesion of the glue to the wood. In addition to wood having a high polarity it also has a relatively high porosity. The wood glue is actually absorbed into the wood to form a mechanical interlocking bond.
When two or more pieces of wood are glued together in this manner the resulting bond is often stronger than the wood itself.
In order to provide a mechanical interlocking bond between a bonding agent and a substrate it is common practice to roughen the surface or even drill small holes. While this practice often produces strong bonding by improving mechanical anchorage, it has one major drawback. Sharp edges resulting from scratching or drilling holes in the substrate become points of stress which can later initiate cracking or even breakage of the bonding agent/or agents. Because of this, numerous methods have been employed to enhance mechanical anchorage of a bonding agent to a bonding surface while minimizing points of stress.
U.S. Pat. No. 4,202,055 outlines the use of ceramic particulate of a material having a diameter of between 0.5 mm and 1.0 mm incorporated in a polymer for the purposes of anchoring a highly stressed endoprostheses. With time after implantation, the ceramic material dissolves away and is replaced by bone tissue. Bioactivating bonding residues aid in bone growth. The result is bone growth in spherical nodules embedded into a polymer.
The spherical shape of the resulting bone nodules significantly reduces the chances of stress fracture formation over time and under the conditions of abuse. Although advantageous in many respects, in the case of brittle bones, the point where the spherical nodule meets the main surface of the bone is a possible failure point.
Another related bonding method involves the attachment of particulate material to a substrate prior to bonding. U.S. Pat. No. 4,927,361 uses this technique to provide dental attachments that will form a good bond to a tooth surface. The particulate coating may take the form of discrete particles, or alternatively may form one or more layers. The result is that mechanical interlocking occurs between the substrate and the adhesive material that bonds the substrate to the tooth.
U.S. Pat. No. 4,854,496 discloses a method of producing a porous metal-coated substrate by diffusion bonding of metal powder particles. Pressure is used to push the particles into the substrate allowing for bonding to occur at reduced temperatures. The diffusion process itself is carried out in a non-reactive atmosphere below the temperatures normally required for sintering. The result is a sintered porous surface which is suitable for bonding to a second substrate and which provides good mechanical interlocking with a suitable bonding agent.
Also worthy of mention is the use of discrete microspheres continuous with a surface substrate. Experiments in this area have been carried out in the area of dentistry. Allan H. Elder, the author of this patent, has prepared bonding surfaces suitable for bonding Maryland bridges. Although these results were successful, improved interlocking characteristics may be obtained by employing multiple layers of these spherical shaped particles.
The above prior art references disclose several methods for achieving bonding between two surfaces. Of particular interest is the use of substantially spherically shaped particles on a substrate surface to improve bonding. The result is a bonding surface having interlocking characteristics with virtually no tendency to produce points of stress.
While these methods provide bonding substrates for various purposes, further improvements in bonding may be realized by employing the teachings of this invention. For example, no mention is made of a truly continuous piece of substrate material possessing interlocking characteristics prior to bonding. The advantages of such a substrate are that it will have material properties that are uniform throughout and therefore posses few if any areas of discontinuity. Such a substrate would be desirable owing to the fact that areas of discontinuity represent possible sources of failure. Such areas or zones of discontinuity include interfacial zones, intercrystalline phase boundary zones, and possible surface contamination at the interface. Employing multiple layers of bonding particles increases the number of these zones in these substantially discontinuous structures. The result is an increase in the likelihood of stress cracks, detachment, or even breakage.
It is therefore an object of this invention to provide a bonding surface having a continuous phase with the substrate.
It is a further object of this invention to provide a bonding surface having good interlocking properties.
It is a further object of this invention to provide a bonding surface having virtually no points of stress.
It is still another object of this invention to provide a bonding surface which may be easily prepared using low cost materials and equipment.
SUMMARY OF THE INVENTION
This invention therefore proposes the preparation of one or more bonding surfaces consisting of multiple layers of substantially spherically shaped nodules protruding from a continuous substrate. These protruding nodules are part of the substrate itself and are formed during the manufacturing process. The resulting substrates have unusually good bonding properties to a wide range of materials and exhibit virtually no tendency to initiate breakage or failure.
Various methods may be employed to prepare such substrates including the lost wax process. The lost wax process has been employed for years in the metal casting industry and is a preferred method for preparing many of the bonding substrates outlined of this invention.
The bonding substrate may be made from any number of materials including pre-formed composite components, metal parts and pieces, or even ceramic materials such as porcelain.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an enlarged view of a bonding surface of prior art employing spherical particles that have been diffusion bonded under pressure to a substrate.
FIG. 2 shows an enlarged view of a bonding surface employing spherical particles having a continuous phase with the substrate.
FIG. 3 shows a bonding surface of this invention employing multiple layers of spherical particles that were formed as part of the substrate.
FIG. 4 shows a part which is used to make a lost wax mold for casting the final bonding substrate of this invention.
FIG. 5 shows two parts that have been bonded together using the teachings of this invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a bonding surface 2 prepared in accordance of the prior art practice of sintering, namely, the use of pressure to push particles of similar or the same material into a surface at elevated temperatures. Spherical particles 4 and 5 are shown embedded into surface portion 6 of substrate 7 . Also shown are outermost surface portions 9 and 11 of spherical particles 4 and 5 . The resulting bond that forms between surface portion 6 of substrate 7 and outermost surface portions 9 and 11 of spherical particles 4 and 5 represents a zone of discontinuity in the direction, size and type of crystals of material. In particular, a phase boundary 10 exists at the point of contact. Phase boundary 10 is susceptible to breakage. Individual crystals 8 of spherical particles 4 and 5 are oriented in different directions than individual crystals 12 of substrate surface portion 6 .
FIG. 2 shows a bonding surface 14 prepared in accordance with the continuous phase and material aspects of this invention. Spherical particles 16 and 18 are continuously attached to substrate 20 at attachment points 22 and 24 . Individual crystals 26 and 28 are also shown. As an be seen from the diagram, particle 16 has crystals 26 which are continuous in phase, structure, and direction with substrate 20 . As such, attachment point 22 is highly resistant to breakage and thus forms a very strong bond between substrate 20 and particle 16 . It can also be seen that particle 16 itself is very strong due to the fact that the direction of crystallinity remains the same throughout with no intercrystalline phase boundaries present.
Particle 18 is not as strong as particle 16 , however there is substantial continuity in the direction of crystallinity at attachment point 24 . Because of this continuity, attachment point 24 is also quite strong and resistant to breakage.
FIG. 3 shows a bonding surface having multiple layers of spherical particles with uniform material properties throughout. Bonding surface 26 is shown having a substrate portion 28 and spherical particles 30 . Spherical particles 30 are numerous and form first layer 32 . Additional spherical particles 34 are also shown. Spherical particles 34 form a second layer 36 on top of first layer 32 . This multiple layer aspect of this invention provides a substantially porous surface with good interlocking properties to liquid bonding agents. Such liquid bonding agents are materials which are applied to the surface as liquids, penetrate into the voids between particles and harden to form a solid mass. The result is a strong interlocking bond having virtually no unwanted points of stress. There are numerous methods that may be employed to form this type of structure; however, the lost wax process is one of the easiest methods to describe and use.
The lost wax process starts out by making a wax blank part that is identical in dimensions to the desired finished part. This wax part is then placed into a ceramic material that is resistant to heat and somewhat porous. The wax part is then used to make a mold by pouring the ceramic material over the wax blank and letting the ceramic material harden. Once hard, the ceramic mold with the wax blank is heated to burn out the wax leaving a void space in the shape of the desired part. The mold is then used to make the part out of the desired material. Once finished, the mold may be broken and the part removed. This process is well known art and is sometimes referred to as investment casting. It is a standard method used to make numerous parts in industry. It is well suited for casting final parts in metal. The part that is used to make the mold does not have to be wax. There are several other materials such as nylon or polyethylene that can be used as well.
FIG. 4 shows a wax and nylon part 42 that can be used to make a lost wax type of mold for casting the final bonding surface of this invention. Wax substrate 38 is shown having multiple layers of nylon beads 40 attached. Pressure sensitive adhesive 41 is also shown which is used to temporarily hold nylon beads 40 to wax substrate 38 and to each other. Wax and nylon part 42 having multiple layers of nylon beads 40 may be easily prepared. Wax substrate 38 is first coated with a thin layer of a pressure sensitive adhesive 41 . Suitable pressure sensitive adhesives have low surface energies and may be based on rubber. Numerous companies manufacture these adhesives including Avery Dennison Corporation of Pasadena, Calif. Small nylon beads 40 are then sprinkled onto this tacky surface to form a single layer. A thin second layer of pressure sensitive adhesive 41 is then applied to the top surface of attached nylon beads 40 . A second layer of nylon beads 40 is then applied to form the second layer. Numerous layers may be applied in this manner, however the best number of layers will depend on the particle size of the spherical beads and other parameters.
FIG. 5 shows two pieces of material bonded together using the teachings of this invention. Complete construction 44 is shown in cross section. Metal substrate 46 is shown having a first layer 48 of spherical shaped particles 50 firmly attached. Spherical particles 50 are made of the same material as metal substrate 46 and are continuous in phase with the substrate. Also shown is a second layer 52 of spherical particles 50 .
Second layer 52 of spherical particles is continuous in material and phase with first layer Because of this, there is virtually no tendency for spherical particles 50 to separate from either each other or from metal substrate 46 . The strength advantages of the continuous material and continuous phase nature of these constructions are substantial. The reasons for this are well known in the art of material science. Many materials have points of weakness when the direction of crystallinity changes. This zone of changing crystallinity is often referred to as a crystalline phase boundary. A phase boundary may result from a change in material, a change in crystalline structure, or even a change in the direction in crystal growth. Materials possessing these phase boundaries are susceptible to breakage at the boundary. Bonding agent 54 is shown interlocked into the voids between spherical particles. Although the phase of bonding agent 54 is clearly different from that of metal spherical particles 50 , the bonding mechanism of bonding agent 54 relies on mechanical interlocking.
Second substrate 56 is also shown. Second substrate 56 may be of the same material as substrate 46 , or alternatively may be of a different material. Spherical particles 58 are shown attached to substrate 56 . Spherical particles 58 are composed of the same material as substrate 56 . Spherical particles 58 are also continuous in phase with substrate 56 .
Those skilled in the art will understand that the preceding exemplary embodiments of the present invention provide a foundation for numerous alternatives and modifications. These other modifications are also within the scope of the limiting technology of the present invention. Accordingly, the present invention is not limited to that precisely shown and described herein but only to that outlined in the appended claims.
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A system and method of bonding is disclosed which is suitable for providing a strong interlocking adhesive bond between two surfaces. At least one bonding surface is provided with multiple layers of spherical shaped protrusions. The multilayer spherical bonding surface is formed from the substrate and therefore is continuous. Many methods may be employed to form this surface, including the lost wax casting process. Such bonding surfaces provide good interlocking properties for bonding agents such as epoxy resins and ceramics. In addition, the uniform curvature of the spherical particles themselves reduces points of stress thereby substantially reducing or even eliminating the formation of stress fractures.
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This is a continuation of Ser. No. 09/009,657, now U.S. Pat. No. 6,022,329, filed Jan. 20, 1998, which is a continuation of Ser. No. 08/559,133, now U.S. Pat. No. 5,718,668, issued Feb. 17, 1998 filed Nov. 17, 1995 which is a continuation of Ser. No. 08/049,144, filed Apr. 19, 1993, now U.S. Pat. No. 5,470,305.
FIELD OF THE INVENTION
This invention relates to a surgical irrigation with a built in pulsing pump.
BACKGROUND OF THE INVENTION
Grulke et al U.S. Pat. No. 5,046,486, assigned to the Assignee of the present invention, discloses a surgical pulsed irrigation handpiece which produces a pulsed irrigation liquid output capable of loosening and floating debris at a surgical site for subsequent removal (as by suction). This prior pulsed irrigation handpiece has been on the market for several years and has proved generally effective for its intended use and hence has been popular in the surgical community.
However, in a continuing effort to improve on existing devices of this general kind, the present invention has been developed. As compared to the above-mentioned prior device, a pulsed irrigation handpiece embodying the present invention is producible at lower cost, produces sharper liquid pulse transients (particularly the pulse “off” transient), requires no connection to any operating room power source (e.g. compressed air) or to an external pump, and instead is self-contained, requires only external connection to a irrigation liquid source (e.g. conventional irrigation liquid bag), provides better suction (when suction is required), is more compact, and is conveniently shaped to be held either as a pistol or a wand (by the handle or barrel).
Other objects, purposes and advantages of the invention will be apparent to those acquainted with apparatus as general kind upon reading the following description and inspecting the accompanying drawings.
SUMMARY OF THE INVENTION
A pulsed irrigation handpiece comprises pulsed irrigation liquid outlet means for applying liquid pulses to a surgical site, pump means reciprocatingly drivable for pumping pulses of irrigation liquid through said outlet means, powered drive means for reciprocatingly driving said pump means and housing means containing said pump means and drive means.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial view of a handpiece embodying the invention.
FIG. 2 is a laterally exploded pictorial view of the FIG. 1 handpiece.
FIG. 3 is an enlarged elevational view of the FIG. 1 handpiece with the leftward housing part removed.
FIG. 4 is a view similar to FIG. 3 but with the suction hose removed, the left drive unit shell part removed and the drive unit exposed in central cross-section, such that FIG. 4 approximates a central cross-sectional view of the FIG. 1 handpiece.
FIG. 4A is an enlarged fragment of FIG. 4 detailing the rearward portion of the handle.
FIG. 4B is an enlarged fragmentary pictorial view, taken from the front, of the electrical contact support posts seen in FIG. 4 A.
FIG. 4C is an enlarged fragmentary exploded pictorial view of the electrical contacts, associated with the FIG. 4B posts and associated electrical conductors from the battery supply.
FIG. 5 is an enlarged, exploded, pictorial view of the drive unit of FIG. 2 .
FIG. 6 is a sectional view substantially taken on the line 6 — 6 of FIG. 5, and provides a top view of the bottom drive unit shell part of FIG. 5 (the rightward one of FIG. 2) with the drive components removed to show the interior configuration of that shell part.
FIG. 7 is a sectional view substantially taken on the line 7 — 7 of FIG. 5, and provides a view similar to FIG. 6 but showing the interior configuration of the other drive unit shell part (the upper one in FIG. 5 and leftward one in FIG. 2 ).
FIG. 8 is an enlarged central cross-sectional view of a tip unit usable with the handpiece of FIG. 2 and showing same installed in a pump unit shown in central cross-section substantially as in FIG. 4 .
FIG. 8A is a reduced size, fragmentary, side elevational view of the apparatus of FIG. 8 .
FIG. 8B is a pictorial view of the apparatus of FIG. 8 A.
FIG. 9 is an end elevational view of the drive unit, taken from the right end in FIGS. 2 and 3.
FIG. 10 is a sectional view substantially taken on the line 10 — 10 of FIG. 5 and showing the drive unit with one shell part (the left one in FIG. 2 and top one in FIG. 5) removed to show the motor and transmission.
FIG. 11 is an elevational view of the drive train substantially taken on the line 11 — 11 of FIG. 10 .
FIG. 12 is a central cross-sectional view substantially taken on the line 12 — 12 of FIG. 10 .
FIG. 13 is a fragmentary cross-sectional view substantially taken on the line 13 — 13 of FIG. 10 .
FIG. 14 is a cross-sectional view substantially taken on the line 14 — 14 of FIG. 10 .
FIG. 15 is a sectional view substantially taken on the line 15 — 15 of FIG. 10 .
FIG. 16 is an exploded pictorial view of the pump unit of FIG. 2 in an enlarged scale.
FIG. 17 is a front end elevational view of the pump unit of FIG. 16 taken substantially from the left side of FIGS. 2-4 and 16 .
FIG. 18 is a central cross-sectional view of the pump unit of FIG. 17 taken substantially on the line 18 — 18 of FIG. 17 .
FIG. 18A is a fragment of FIG. 18 showing the pump unit at the beginning of an intake stroke.
FIG. 18B is a fragment of FIG. 18 showing the pump nearing the end of an output pulse.
FIG. 18C is a fragmentary enlargement of FIG. 18 showing the valve member.
FIG. 19 is a fragmentary cross-sectional view showing the connection of the pump unit to the liquid supply hose.
FIG. 20 is a pictorial view of the electric power supply unit connected to the FIG. 2 handpiece.
FIG. 21 is a left end view of the FIG. 20 electric power supply unit.
FIG. 22 is an exploded pictorial view of the electric power supply unit of FIG. 20 .
FIG. 22A is an electrical schematic of the FIG. 2 handpiece and FIG. 20 electric power supply unit.
FIG. 23 is a central cross-sectional view taken substantially on the line 23 — 23 of FIG. 22 .
FIG. 23A is an enlarged fragmentary pictorial view of the support structure for battery contacts at the forward (left in FIG. 23) end of the electric power supply casing.
FIG. 23B is an enlarged pictorial view similar to FIG. 23A but showing the support structure for battery contacts at the rearward (rightward in FIG. 23) end of the power supply casing.
FIG. 24 is a sectional view substantially taken on the line 24 — 24 of FIG. 22 and showing the electric power supply unit with its top cover removed.
FIG. 25 is a sectional view substantially taken on the line 25 — 25 of FIG. 22 and showing the underside of the cover of the power supply casing.
FIGS. 26, 27 and 28 are enlarged pictorial views of battery contacts of FIG. 22 .
FIG. 29 is an enlarged fragmentary pictorial view of an embodiment of the liquid supply and electric wiring harness of the apparatus of FIGS. 2 and 20 but showing a modification in the attachment of the electrical and liquid handling components.
In the following detailed discussion the terms “up”, “down”, “right” and “left”, and variations thereon, refer to structural elements in their positions in specified drawing FIGURERS.
DETAILED DESCRIPTION
A pulsed irrigation handpiece 10 (FIGS. 1 and 2) embodying the invention comprises a hand-held housing 11 having a handle 12 and a barrel 13 which extends forward from the upper end of the handle 12 at about a 130° to 150° (here about 145°) angle thereto.
The housing 11 is hollow and, for convenience in assembling the handpiece 10 , is constructed as laterally opposed concave left and right housing parts 14 and 15 (FIG. 2 ). The housing parts 14 and 15 are preferably molded rigid plastic elements held together rigidly by any convenient means, here comprising undercut snap fit tabs 16 protruding from the top and bottom edges of the right housing part 15 to snap over an interior edge flange (not shown) on the top and bottom edge of the left housing part 14 . If desired, precise registry together of the two housing parts can be assisted by laterally projecting pins 20 distributed along the edges of one housing part (here the left housing part 14 ) piloted in holes 21 (FIG. 4) in the opposed edges of the other housing part (here 15 ). Upon completion of assembly of the handpiece 10 , the two housing parts 14 and 15 may be adhesively bonded together. The handpiece is intended to be a disposable item and therefore access to the interior of the housing for purposes of repair is not needed.
Drive Unit
The drive unit 25 (FIGS. 2-15) is self contained in its own shell 26 (FIG. 2 ). For convenience in assembly, the shell 26 comprises two opposed concave shell parts 30 and 31 respectively disposed to the left and right in FIG. 2 . The shell parts 30 and 31 are preferably of rigid molded plastics material. When the drive unit 25 has been assembled, as in FIGS. 2 and 9, the shell parts 30 and 31 are held fixedly together by any convenient means, here by resilient snap connection of generally U-shaped clips 32 , molded in spaced relation along the perimeter edge of the shell part 31 which overlap the perimeter edge of the shell part 30 and snap over tabs 33 protruding therefrom, as seen in FIGS. 5-7. Precise location of the shell parts 30 and 31 with respect to each other is assisted by locator pins 34 fixedly protruding from the shell part 31 and holes 35 in the opposed portions of the shell part 30 .
A conventional DC energizable electric motor 36 (FIGS. 4 and 5) is snugly housed in the space between the left and right (FIG. 2) shell parts 30 and 31 at the rear (left in FIGS. 5-7, 10 and 12 ) thereof. The motor 36 is snugly axially located between the rear end wall 40 and a transverse internal bulkhead 41 of the shell 26 (FIGS. 5-7, 10 and 12 ). The rear end wall 40 and bulkhead 41 have opposed parts in the left and right shell parts 30 and 31 , as seen in FIGS. 6 and 7.
Rear and front bosses 42 and 43 respectively extend rearward and forward from the cylindrical casing 44 of the motor 36 , as seen in FIGS. 10 and 12 ), and are supported in corresponding coaxial recesses 45 and 46 in the rear end wall 40 and bulkhead 41 respectively, so as to support the motor casing 44 with respect to the shell 26 . A flat 47 on the rear boss 42 (FIG. 9) co-acts with a corresponding flat in the surrounding recess 45 to prevent rotation of the motor casing 44 with respect to the shell parts 30 and 31 , such that the motor 36 is antirotationally fixed within the shell 26 .
The drive unit 25 further includes a transmission 50 (FIG. 5) coaxial with and forward of the motor 36 . The transmission includes a reciprocating link member 51 and is driven from the forward extending, rotating output shaft 52 of the motor 36 . The shaft 52 extends coaxially forward through the front boss 43 (FIG. 12) of the motor 36 .
The transmission 50 (FIGS. 5 and 12) includes a pinion gear 53 fixed on the motor shaft 52 for rotation thereby, and a face gear 54 which, as seen in FIG. 12, underlies the pinion gear 53 . The face gear 54 has a relatively large diameter central disk 56 carrying upward facing teeth 55 engaging corresponding teeth on the pinion gear 53 for rotation thereby. The face gear 54 includes a secondary pinion gear 57 fixed coaxially beneath the disk 56 , and of substantially lesser diameter, which in turn drives a relatively large diameter output gear 60 .
It will be understood that the pinion gear 53 , face gear 54 , secondary pinion 57 and output gear 60 are all provided with a full circumferential (360°) set of teeth, so that continuous rotation of the motor shaft 52 results in continuous rotation of the output gear 60 .
For convenience in drawing, some or all the gear teeth are not shown in various of the drawings, the toothed meshing connection of the gears therein thus being only schematically shown. See for example FIGS. 4, 10 , 12 , 13 and 14 .
An output shaft 61 is fixed to and coaxially upstanding from the output gear 60 (FIG. 12) and fixedly rotatably drives an eccentric member 62 (FIGS. 5, 10 and 12 ) spaced above the output gear 60 . In this embodiment, the output shaft is of rectangular cross-section to maximize its torque transmitting capability.
The eccentric member 62 comprises a radially extending disk 63 (FIG. 5) coaxial with the output shaft 61 and fixedly surmounted by an eccentric circular cylinder 64 eccentrically rotatable with the output shaft 61 .
The link member 51 is generally T-shaped, as seen in FIG. 13, having a plate-like body 70 overlying the disk 63 of the eccentric member 62 and lying at right angles to the output shaft 61 , and further having a plate-like fork 71 fixed at the rightward (FIGS. 5, 10 , 12 and 13 ) end of the plate-like body 70 and extending in a plane substantially parallel to the output shaft 61 . The plane of the plate-like fork 71 is perpendicular to the intended direction of reciprocating movement of the link member 51 . The body 70 , at its end portion remote from the fork 71 , has an oblong through opening 72 snugly radially receiving the rotating eccentric cylinder 64 of the eccentric member 62 , as seen in FIG. 10 . More particularly, the length direction of the oblong opening 72 extends parallel to the plane of the fork 71 and is of sufficient length to accommodate 360° rotation of the eccentric cylinder 64 without movement of the body 70 parallel to the plane of the fork 71 . On the other hand, the width of the oblong opening 72 , namely in a direction perpendicular to the plane of the fork 71 , corresponds substantially to the diameter of the eccentric cylinder 64 , providing a sliding clearance between the body 70 and eccentric cylinder 64 , so that rotation of the eccentric cylinder 64 will result in reciprocation of the link member 51 in a direction perpendicular to the plane of the fork 71 .
The plate-like body 70 includes a thickened rim 73 (FIG. 5) around the oblong opening 72 and may thus be said to form a yoke for coaction with the eccentric cylinder 64 . The side edges of the body 70 are preferably also thickened to form parallel longitudinal guide rails 74 (FIG. 10 ).
The above discussed moving elements of the transmission 50 are located and movably supported within the shell 26 as follows. The face gear 54 has coaxial downward and upward (FIGS. 5-7, 10 and 12 ) extending stub shafts 75 and 76 respectively rotatably supported in coaxial bearing bosses 80 and 81 respectively fixed on the opposing faces of the shell parts 31 and 30 (FIGS. 6, 7 and 12 ). Similarly, the output gear 60 and the eccentric member 62 have respective downward and upward extending stub shafts 82 and 83 coaxial with the output shaft 61 and rotatably supported in respective cylindrical bearing bosses 84 and 85 in the respective shells 31 and 30 (FIGS. 5-7 and 12 ). The link member 51 is slidably guided for reciprocation in a notch 90 (FIGS. 5 and 7) in the peripheral wall 91 of the left (upper in FIG. 5) shell part 30 . The notch 90 has parallel opposed guide faces 92 (FIG. 7) spaced apart to snugly slidably guide therebetween the opposite guide rails 74 of the link member 51 , and thus spaced at substantially at the maximum width of the link member. The thickness of the link member is guided for reciprocation between the peripheral edge 93 of the right (lower in FIG. 5) shell 31 and the width wall 94 (FIGS. 5 and 7) of the other shell part 30 .
The central length axis LA (FIG. 10) of the link member intersects the central length axis MA of the motor shaft 52 at the axis SA of the output shaft 61 and stub shaft 83 (FIGS. 10 and 12 ), at an angle equal to the angle between the central length axis of the handle 12 and barrel 13 of the housing 11 . Moreover, the length axes of the handle and barrel also intersect at the axis SA of the output shaft 61 when the drive unit is installed in the handpiece housing 11 as hereafter discussed. In effect then, the link member longitudinal axis LA and motor shaft axis MA define the length axis of the barrel 13 and handle 12 , respectively, when the drive unit 25 is installed in the handpiece housing 11 .
The drive unit 25 is located within the handle 12 , as follows. As seen in FIGS. 3 and 4, transverse ribs 95 are molded into the interior surface of the handle 12 at opposing locations in the left and right housing parts 14 and 15 (FIGS. 2 - 4 ). For drawing convenience, only the ribs in the right housing part 15 are shown, the ribs in the left housing part 14 being compatible. The ribs 95 locate the drive unit 25 in the rightward/leftward direction in FIG. 2 . Further, the drive unit shell bosses 84 and 85 (FIG. 5) protrude sideways from the drive unit shell and are pivotally received in corresponding hollow cylindrical bosses, one of which is shown at 96 in FIG. 2, and which extend toward each other from the interior of the left and right housing parts 14 and 15 . The hollow cylindrical boss 96 of the left housing part 14 is not shown but is opposed to and compatible with the housing part 96 shown in the right housing part 15 of FIG. 2 . The drive unit 25 is thus, except for the lateral positioning defined by the ribs 95 , pivotally located within the handpiece housing 11 and is thus capable of some pivotal floating in the housing to achieve proper alignment of the longitudinal movement axis LA (FIG. 7) of the link member 51 with respect to the barrel 13 and a pump unit 100 (FIGS. 2-4 and 16 - 18 ) located in the barrel 13 as hereafter discussed.
Pump Unit
Turning now to the pump unit 100 , attention is directed to FIGS. 2-4 and 16 - 18 . The pump unit 100 includes a bellows 101 including an axially expandable and contractible flexible bellows wall 114 (FIG. 18) and a forwardly extending, rigid, annular flange wall 102 . Such flange wall 102 is loosely telescoped over a rigid rearwardly extending annular flange 103 of a rigid, forwardly extending coaxial bellows housing 104 .
The bellows 101 and bellows housing 104 are preferably of molded plastics material. A resilient O-ring 105 (FIGS. 16 and 19) is snugly radially disposed between the radially opposed, axially extending annular flanges 102 and 103 , to create a fluid seal therebetween and hence between the bellows 101 and bellows housing 104 , to prevent fluid leakage therebetween. The bellows 101 and bellows housing 104 have respective axially spaced radially extending steps 106 and 107 joined to the respective annular flanges 102 and 103 and axially spaced apart at a distance substantially greater than the diameter of the O-ring 105 , as seen in FIG. 19 . The axial extending flanges 102 and 103 and radially extending steps 105 and 106 define an annular chamber 110 in which the O-ring 105 is axially loosely, and radially snugly and sealingly, disposed. Note that the radially opposed surfaces of the axially extending annular flanges 102 and 103 are cylindrical, such that neither has an annular groove in which the O-ring seats. Thus, the O-ring is free to roll on the radially opposed cylindrical surfaces of the axially extending flanges 102 and 103 and the O-ring 105 does not significantly interfere with axial separation of the bellows 101 and bellows housing 104 from each other.
Instead, such axial separation is prevented, as hereinafter further discussed, by a forwardly-rearwardly (leftwardly-rightwardly in FIG. 2) spaced pair of ribs 111 (FIG. 2) extending radially inward from the interior wall of the right housing part 15 and a corresponding, laterally opposed pair of mirror imaged ribs (not shown) extending laterally inward from the interior wall of the left housing part 14 . Such ribs 111 are also schematically indicated in FIG. 18 .
The rear (right in FIG. 19) end of the bellows housing axial flange 103 abuts the radially extending step 106 of the bellows 101 and the forward (leftward in FIG. 19) end of the bellows axial flange 102 axially abuts a radial flange 112 which extends radially outward from and forwardly from the bellows housing step 107 . The forward end of the bellows axial flange 102 thus radially overlaps the bellows housing step 107 in snug but axially slidable relation thereto. A small forwardly extending annular rib 113 protrudes forwardly from the bellows radial step 106 toward the O-ring 105 to prevent rearward escape of the O-ring 105 from the space between the axially extending flanges 102 and 103 , in the event of slight axial shifting of the bellows 101 and bellows housing 104 away from each other.
The above mentioned radially inward extending ribs 111 of the handpiece housing 11 snugly axially oppose and sandwich therebetween the bellows radial step 106 and bellows housing radial flange 112 to positively prevent axial separation of the bellows 101 from the bellows housing 104 , when the pump unit 100 is installed in the housing 11 .
The above-mentioned bellows wall 114 extends rearward from the inner periphery of the radially extending annular step 106 of the bellows 101 (FIG. 18) and consists of an axially collapsible and extensible, flexible, wave cross-section, peripheral wall 114 . The bellows wall 114 surrounds an axially expansible and contractible pumping chamber 115 . At the rear end of the bellows 101 , a radially extending drive end wall 116 closes the rear end of the bellows wall 114 and pumping chamber 115 . A stub 120 , having a radially enlarged head 121 , is fixed to and extends coaxially rearwardly from the drive end wall 116 .
To axially reciprocatingly drive (repetitively axially contract and expand) the bellows 101 , the above discussed link member 51 (FIG. 5) of the drive unit 25 has its fork 71 provided with a central, radially opening, generally U-shaped slot 122 (FIGS. 11 - 13 ). The slot 122 divides the fork 71 into a pair of tines 123 (FIG. 11 ). The slot 122 opens leftwardly in FIG. 2, namely away from the rightward housing part 15 and toward the leftward housing part 14 . Thus, with the drive unit 25 located in the right housing part 12 as seen in FIG. 3, the pump unit 100 can be inserted into the rightward housing part 15 , with the stub 120 (FIG. 18) inserted in the slot 122 of the fork 71 (FIG. 11) so as to trap the tines 123 axially between the drive end wall 116 and head 121 of the bellows 101 , as generally indicated in FIGS. 3 and 4. To prevent the bellows stub 120 from accidentally radially escaping out the open end of the slot 122 in the fork 71 , the central portion 124 (FIG. 11) of the slot 122 is undercut by inward tapering of an intermediate portion 125 of the slot 122 as seen in FIG. 11 . The tapered portion 125 of the slot 122 (FIG. 11) defines a snap fit detente for resiliently trapping the bellows stub 120 in the drive unit slot 122 . Thus, to install the bellows stub 120 in the slot 122 , the bellows stub 120 must be resiliently forced through the tapered portion 125 of the slot 122 and upon passing the latter, the stub resiliently snaps into the central portion 124 of the slot. The inner ends of the tapered portion 125 of the slot resiliently maintain the stub radially inboard thereof, in the central portion 124 of the slot 122 .
The stub 120 and hence the bellows 101 , and indeed the entire pump unit 100 , is thus freely rotatable about its length axis with respect to the fork 71 , so that the circumferential orientation of the drive unit 25 and the pump unit 100 is determined by the location thereof in the housing. The drive unit 25 and pump unit 100 are thus, to an extent, free to circumferentially float with respect to each other, about the connection of the stub 120 and fork 71 , without interfering with the circumferential location of the drive unit 25 and pump unit 100 in the housing 11 . Further, the edges of the slot 122 , in particular of the central portion 124 thereof, are rounded in cross-section, as is the stub 120 , to permit a modest amount of angular adjustment between the length axes MA and LA of the drive unit 25 and pump unit 100 and to allow the drive unit 25 and pump unit 100 to easily settle into their proper operating positions in the housing 11 .
A cylindrical plug 126 is coaxially fixed to the interior side (left side in FIG. 18) of the bellows drive end wall 116 by a coaxial, rearward extending, undercut pin 127 snap fitted in a forwardly (leftwardly in FIG. 18) opening recess in the stub 120 . The plug 126 has a diametral slot 130 opening forward from its front end and which faces forward toward a resilient valve member 131 (FIGS. 16 and 18) to maintain liquid communication between the central and radially outer portions of the pumping chamber 115 .
The bellows 101 is thus a single element which carries out four different functions, namely sealing at the forward end, changing the pump chamber size in the middle thereof, the rearend acts as a piston and as a drive point. In addition, the front annular flange 102 helps locate the pump unit with respect to the housing barrel.
The pump unit 100 further includes a valve member 131 , which is a one piece member of suitable resilient material and which by itself constitutes the entire moveable inlet and outlet valve system for the pump unit 100 . More particularly, the valve member 131 comprises a short tubular central portion 132 (FIG. 18) which coaxially connects a forward (leftward in FIG. 18) tapering, duck bill type, outlet valve 133 and a rearwardly and radially outwardly extending umbrella type, inlet valve 134 . The umbrella valve 134 is annular and has a central opening 135 which communicates coaxially from the pumping chamber 115 in the bellows 101 forwardly through the tubular central portion 132 and outlet duck bill valve 133 of the valve member 131 .
The bellows housing 104 comprises a rear (right in FIGS. 18 and 18C) facing recess having a perimeter defined by the annular flange 103 of the bellows housing 104 and a rear facing radial wall 136 which defines the front end of the pumping chamber 115 . The umbrella valve 134 lies coaxially in the resulting recess 103 , 136 . The forward facing perimeter 137 of the umbrella valve 134 , in its closed condition shown in FIGS. 18 and 18C, presses forward against the radial wall 136 to seal thereagainst. The valve member 131 is held against the right (rearward) movement away from the bellows housing wall 136 by axial interference between a rightward facing, radially outward extending, annular step 140 (FIG. 18C) at the rear (right) end of the duck bill valve 133 , and a radially inward extending, leftward facing, annular flange 141 of the bellows housing 104 . The radially inward directed, annular flange 141 is axially interposed between, and forms a port 142 between, the rear facing recess 103 , 136 and a coaxial, forwardly extending, cylindrical, irrigation liquid outlet conduit 143 (FIGS. 18 and 18 C). The tubular central portion 132 of the valve member 131 extends snugly axially through the port 142 .
To install the valve member 131 in the bellows housing 104 , the tapered outlet duck bill valve 133 is pushed forward through the port 142 , the bellows valve step 140 snaps forwardly (leftwardly in FIG. 18C) past the bellows housing flange 141 , and the sealing perimeter 137 of the umbrella valve 134 is thereby pulled forwardly resiliently against the rearward facing bellows housing wall 136 , leaving the valve member 131 with its duck bill valve 133 and umbrella valve 134 both in their closed condition shown in FIGS. 18 and 18C.
The bellows housing 104 further includes an annular liquid jacket 144 (FIGS. 18 and 18C) surrounding the rear portion of the liquid outlet conduit 143 and defining radially therebetween an annular liquid inlet chamber 145 (FIGS. 18, 18 C and 19 ). The inlet chamber 145 communicates between a radial inlet port 146 (FIGS. 16 and 19 ), which opens radially outward through the side of the bellows housing 104 , and an annular space 147 (FIG. 18 C). The annular space 147 is bounded by the forward face 150 and tubular central portion 132 and sealing perimeter 137 of the umbrella valve 134 and the radial face 136 of the recess 103 , 136 of the bellows housing 104 .
Thus, a rightward pullback of the bellows head 121 axially expands the bellows, from its FIG. 18A position towards its FIG. 18 position. This reduces the pressure within the bellows. This in turn keeps the duck bill valve 133 closed and pulls the sealing perimeter 137 of the umbrella valve 134 rightwardly away from the bellows housing recess radial wall 136 and draws liquid from the port 146 through the annular inlet chamber 145 , around the perimeter 137 of the open umbrella valve and into the interior of bellows.
On the other hand, a leftward push forward of the bellows head 121 axially compresses the bellows from its FIG. 18 position toward its FIG. 18B position and raises the pressure in the bellows, to close the umbrella valve 134 and open the duck bill valve 133 and force a pulse of liquid out of the bellows forwardly through the duck bill valve 133 and liquid outlet conduit 143 .
Irrigation liquid is drawn to the inlet port 146 of the bellows housing 104 through an elbow 151 (FIG. 19 ). The outlet end 152 of the elbow and the inlet port 146 are cylindrical, with the elbow outlet end 152 being a snug axially sliding fit in the inlet port 146 . An axially elongate, annular groove 153 in the outer periphery of the elbow outlet 152 houses a seal ring, here an O-ring, 154 which bears sealing and rollingly on the radially opposed and surrounding surface of the inlet port 146 to prevent liquid leakage out of the elbow 151 at its interface with the inlet port 146 . The elbow 151 is not mechanically interlocked with the inlet port 146 but can slide in and out with respect thereto. The elbow 151 is held in place with its outlet end 152 sealingly within the port 146 by bearing of a portion 155 (FIG. 4) of the handpiece housing barrel 13 against the outboard surface 156 of the elbow 151 , with the pump unit installed in the handpiece housing 11 . The elbow 151 here fixedly carries a pair of parallel fins 157 (FIGS. 16, 17 and 19 ). The fins 157 extend radially from the rear inlet end portion of the elbow 151 and axially sandwich therebetween the flanges 106 and 112 of the bellows 101 and bellows housing 104 , at least to help the housing ribs 111 (FIG. 18) fins 157 prevent axial separation of the bellows and bellows housing. The housing ribs 111 and fins 157 are more or less evenly circumferentially located around the bellows 101 and bellows housing 104 .
An elongate flexible irrigation liquid supply hose 160 (FIGS. 2, 4 , 16 , 17 , 19 , 22 , 23 , 25 and 29 ) has a forward end 161 which telescopes sealing and fixedly over the rear end 162 of the elbow 151 as seen in FIGS. 19 and 29. Although an annular barb is shown at 162 (for example in FIG. 19) a barbless, cylindrical end 162 is satisfactory. In the assembled handpiece, the irrigation liquid hose 160 extends rearward from the elbow 151 (FIG. 4) in the barrel 13 of the housing and angles downwardly and rearwardly along the bottom of the handpiece handle 12 to exit rearwardly and downwardly through a hole 163 (FIG. 2) in the bottom end wall 164 of the handpiece housing 11 . A clamp plate 165 (FIGS. 2 , 3 and 4 ) of bent cross-section has a perimeter groove 166 for receiving the edges of the hole 163 in the housing bottom end wall 164 , such that the clamp plate 165 is trapped in and partly closes the hole 163 in the bottom end 164 of the housing handle 12 when the housing is fully assembled. A notch 167 (FIG. 2) in the rightward end of the clamp plate 165 permits exit therethrough of irrigation liquid supply hose 160 from the handpiece housing 11 and snugly and frictionally grips such hose, without crushing or collapsing it, so that such hose 160 cannot easily be pulled out of the housing 11 or off the elbow 151 .
The irrigation liquid hose 160 has fixed on the outside thereof, as by extruding or molding integrally therewith, a smaller diameter rib 170 (FIGS. 2, 16 and 17 ). A plurality (here three) of insulated electrical conductors (wires) 171 have intermediate portions contained within and extending the length of the rib 170 . Forward end portions of the insulated wires 171 emerge from the forward end of the rib 170 and carry conventional electrically conductive connectors 175 . The forward end of the rib 170 extends through the notch 167 (FIG. 2) and ends just inside the bottom portion of the handle 12 of the housing 11 , as seen in FIG. 4 . The forward ends of the conductors 171 , carrying the connectors 175 , extend into the lower portion of the handpiece handle 12 for purposes appearing hereinafter.
The insulated electrical conductors 171 extend along the length of the central portion of the liquid supply hose 160 and have rear ends provided with respective electrically conductive connectors 176 (FIGS. 22 and 29 ), such that electric current can flow from a given rear connector 176 through its corresponding insulated electrical conductor 171 and to its corresponding front electrically conductive connector 175 in a conventional manner. Short rear portions of the conductors 171 are loose and moveable with respect to the liquid supply hose 160 as seen in FIGS. 22 and 29.
The electrical connectors 175 and 176 are conventional crimp type connectors.
Instead of being molded in or otherwise constrained within the generally circular cross section rib 170 in FIG. 2, the elongate central portion of the insulated electrical conductors 171 may be fixed side by side, in a flat array, to the outside of the liquid hose 160 , as shown in FIGS. 22 and 29, and such can be accomplished by adhesive bonding or by any other convenient means.
The hose 160 , 170 thus serves the dual use of conveying both irrigation liquid and electric operating power.
The length of the central portion of the liquid hose 160 , to which the insulated conductors 170 are fixed, preferably extends several feet (for example 8 to 10 feet) from the handpiece 10 . The rear end 177 (FIGS. 22 and 23) of the liquid hose is here provided with a fitting 180 of hollow tubular construction open to axial liquid flow therethrough. The fitting 180 comprises a forward end portion 181 (FIG. 23) fixed sealingly telescoped in the rear end 177 of the liquid hose 160 , a square central flange 182 (FIG. 22) and a rear end portion (or “spike”) 183 having a sharpened tip 184 . The tip 184 is capable of conventional insertion into a conventional source S (FIG. 22) of irrigation liquid, for example a conventional supply bag, for conveying irrigation liquid therefrom forward into the hose 160 . The square flange 182 prevents rotation of the fitting 180 in the casing 191 , which helps when removing the spike 183 from the liquid supply bag. In the embodiment shown, the rear end portion 183 is covered by a protective cap 185 prior to use so that the sharpened tip 184 will not accidentally be dulled.
Thus, the length of the liquid supply hose 160 allows the irrigation liquid source S to be located at a distance from the handpiece and thus out of the way of the surgical personnel at the operating table where the handpiece 10 is to be used.
Electrical Power Supply Unit
To provide operating electrical power to the motor 36 , a compact, self contained electrical power supply unit 190 (FIGS. 20-25) is fixed on the rear end portion 177 of the liquid hose 160 , and is thus located remotely from the handpiece 10 , adjacent to the source S of irrigation liquid.
The power supply unit 190 comprises a casing 191 preferably of rigid molded plastics material. The casing 191 here comprises a relatively deep, substantially rectangular pan 192 (FIG. 2) whose top (as oriented in FIGS. 22 and 23) is fixedly closed by a cover 193 . The pan 192 has front and rear end walls 194 and 195 (FIGS. 23, 23 A and 24 ) having fixed upward opening slots 200 each defined by a laterally spaced, opposed pair of U-shaped flanges 201 (FIGS. 23 A and 23 B). The slots 200 are undercut in that each has a mouth 202 laterally narrower than the remainder of the slot 200 and communicating between the remainder of the slot 200 and the interior cavity of the pan 192 . The undercut slots 200 are of constant cross-sectional size and shape vertically (i.e. into and out of the page in FIG. 24 and up and down in FIG. 23 ).
For convenient reference in the drawings, the reference numerals 200 and 201 are suffixed, so that the undercut slots and U-shaped flanges on the front pan wall 194 are indicated by the reference characters 200 F and 201 F and the undercut slots and U-shaped flanges on the rear pan wall 195 are indicated at 200 R and 201 R.
The U-shaped flanges 201 F defining the slots 200 F on the forward end wall 194 start substantially from the pan bottom wall 196 and extend a bit less than half way up the front end wall 194 .
On the other hand, the U-shaped flanges 201 R of the slots 200 R on the rearward end wall 195 of the pan are spaced above the bottom wall 196 of the pan upon respective block-like pillars 203 which define an up-facing bottom 204 for each of the U-shaped flanges 201 R on the rear pan wall 195 .
Rising from bottom wall 196 of the pan between the two central pillars 203 to a height below the bottoms 204 of the slots 200 R thereof, is a central block 205 from which forwardly extends, along the pan bottom wall 196 , a T-shaped flange 206 (FIG. 23B) of constant cross section vertically and defining a pair of vertically open and laterally oppositely opening grooves 207 disposed immediately forward from the two central pillars 203 on the rear pan wall 195 .
Two such undercut slots 200 F are spaced symmetrically side by side on the front pan wall 194 . Similarly, and at the same effective lateral spacing, two such slots 200 R are spaced laterally side by side on the pan rear wall 195 .
Springy, electrically conductive sheet metal battery contacts of three different kinds are indicated at 210 and 211 and 212 and FIGS. 26, 27 and 28 respectively.
A pair of such contacts 210 are provided and each comprises a generally rectangular foot 213 adapted to snugly slide down into a respective undercut slot 200 F at the pan front wall 194 . Each foot 213 is provided with resilient toes 214 angled out of the plane of the foot 213 and adapted to bite against the interior of the corresponding undercut slot 200 F to fix the corresponding battery contact 210 in place therein.
Similarly, each of a pair of battery contacts 212 (FIG. 28) has a resilient fork-shaped foot 215 adapted to fit snugly and slidingly down into the corresponding undercut groove 200 R at the rear wall 195 of the pan 192 and with springy toes 216 for fixedly gripping the interior of the corresponding undercut slot 200 R.
In a generally similar manner the single, low speed battery contact 211 (FIG. 27) has a resilient U-shaped foot 217 for sliding down over the T-shaped flange 206 (FIG. 23 B), with springy toes 218 bent out of the plane of the foot 217 for bitingly engaging the walls of the grooves 207 of the T-shaped flange 206 .
Each of the battery contacts 210 , 211 and 212 thus slides with its corresponding foot into the desired location with respect to the grooves 200 F, 200 R and 207 and locks fixedly therein. This is generally indicated in FIGS. 22-24. The battery contacts 210 , 211 and 212 have respective resilient fingers 221 , 222 and 223 (FIGS. 26, 27 and 28 respectively), two each for the battery contacts 210 and 211 and one each for the battery contacts 212 . Such fingers 221 , 222 and 223 protrude from the respective slots 200 F, 200 R and 207 into the interior of the pan 192 for electrically contacting batteries 230 (FIG. 22) to be housed in the pan 192 . Further, the battery contact 211 and each of the battery contacts 212 (FIGS. 27 and 28 respectively) have an upstanding terminal ( 224 and 225 respectively) of simple rectangular shape for releasable telescoped engagement within a respective one of the connectors 176 at the rear ends of the three insulated electrical conductors 171 (FIG. 22 ).
Turning now to the arrangement of the batteries 230 within the pan 192 , one embodiment according to the invention advantageously uses batteries of a kind widely available in retail stores, namely AA size alkaline batteries. In addition to their wide availability to the public, these batteries advantageously are inexpensive, have a long shelf life and provide full operating voltage until almost fully discharged. In the embodiment shown, eight such batteries 230 are provided and are individually indicated at B 1 , B 2 , B 3 , B 4 , B 5 , B 6 , B 7 and B 8 . As shown in FIGS. 22-24, ribs 231 extending circumferentially within the pan 192 cradle the batteries 230 fixedly but removably within the pan 192 . The polarity of the eight batteries is indicated by “plus” signs marked thereon. As seen in the drawings, the batteries 230 are arranged in four rows of two head-to-tail batteries each. Four of the batteries 230 lie in the bottom (FIGS. 22 and 23) of the pan in two rows of two each and the remaining four batteries 230 lie on top of those.
The ends of the battery rows bear variously on the above discussed battery contacts 210 , 211 and 212 as generally indicated for example in FIG. 22 and also in the schematic circuit drawing in FIG. 22 A. More particularly, the four batteries B 1 , B 2 , B 3 and B 4 defining a vertical plane nearest to the viewer in FIG. 23 are connected in series from the near connector 212 leftwardly through the top row of batteries, down through the near upstanding connector 210 and thence rightwardly through the bottom pair of batteries to the lower rear connector 211 . The remaining four batteries B 5 -B 8 are arranged in a vertical plane behind above-mentioned batteries B 1 -B 4 . More particularly, the batteries B 5 -B 8 connect in series from the far side of the lower rear connector 211 forwardly (leftwardly in FIG. 22) to the far connector 210 , upwardly therethrough, and then rearwardly back to the far upper connector 212 .
The cover 193 (FIGS. 23 and 25) has plural, laterally extending, depending ribs 232 (FIGS. 23 and 25) intended to seat upon the uppermost batteries B 1 , B 2 , B 7 and B 8 and fix the batteries B 1 -B 8 in the pan with the cover 193 fixed in its normal closed position atop the pan 192 . The cover is fixedly securable atop the pan by any convenient means, such as snap fit connectors, a portion of which are generally shown in 233 in FIG. 22, and generally like those discussed above with respect to the handpiece housing 11 , as at 16 , and as generally discussed with respect to the drive unit shell 26 , as at 32 , 33 .
The aforementioned rear end 177 of the hose 160 extends through the casing 191 along the horizontal parting plane between the pan 192 and cover 193 , and so lies close adjacent the topmost batteries B 1 , B 2 , B 7 and B 8 .
Hollow front and rear bosses 234 and 235 (FIGS. 23 and 25) extend forward and rearward respectively, from the casing 191 . At the parting plane between the pan 192 and cover 193 , the bosses 234 and 235 are notched (for example at 236 in FIG. 22) for extension therethrough of the rear end 177 of the liquid hose 160 . The rear hollow boss 235 is sized and shaped to receive radially therein the square flange 182 (FIG. 23) on the rear end of the liquid hose 160 , and thereby axially fix the rear end of the liquid supply hose 160 within the casing 191 and nonrotatably fix the fitting 180 to the battery casing 191 . The notch 236 in the front boss portion 234 on the cover 193 is indented by one or more small recesses 237 for receiving axially therethrough the rib 170 containing the insulated electrical conductors 171 , whose rear end connectors 176 are respectively fixed to the terminals 224 and 225 of the battery contacts 211 and 212 .
Trigger Unit
The handpiece 10 further includes a trigger unit 240 (FIGS. 2-4) for controlling actuation of the motor 36 . The trigger unit 240 comprises a generally L-shaped trigger member 241 (FIGS. 2, 4 and 4 A) comprising an elongate trigger lever 242 . The upper, forward (leftward in FIGS. 2 and 4) end of the trigger lever is pivoted by laterally extending integral pins 243 pivotally receivable in suitable holes in laterally opposed bosses 244 (one of which is shown in FIG. 2) in the opposing lower edges of the housing parts 14 and 15 , near the rear end of the barrel 13 . Snapping together of the two housing parts 14 and 15 thus captures the pivot pins 243 and pivotally mounts the trigger with respect to the handpiece housing 11 .
The trigger lever 242 includes a transverse ridge 245 (FIG. 4) near to but spaced rearwardly from the pivot pins 243 and facing the underside of the barrel 13 and adapted to bear on the underside thereof in the manner of a fulcrum. By far the major length 246 of the trigger lever 242 is to the rear (right in FIG. 4) of the fulcrum ridge 245 . This rearward trigger part 246 is relatively rigid in the portion thereof spaced at least somewhat to the rear of the fulcrum ridge 245 . Such rigidity is assisted by a forward facing longitudinal reinforcement rib 247 extending rearward along the front face of the trigger lever 242 from a point near the fulcrum ridge 245 . The front of the trigger lever 242 , to the rear of the fulcrum ridge 245 is, in the embodiment shown, provided with transversely extending ribs 248 to provide the user with a non-slip grip of the trigger lever 242 .
The trigger lever 242 is bendable near the fulcrum ridge 245 , both to the front and rear thereof, in a resilient manner. In this way, the resilience of the trigger lever tends to hold it in its forward, inactive position shown in FIG. 4, with the fulcrum ridge 245 bearing on the underside of the handpiece barrel 13 . On the other hand, when the user grips the handle 12 and squeezes the trigger lever 245 toward it, in the direction indicated by the arrow TA in FIG. 4, the trigger lever bends in the region of the fulcrum ridge 245 , tending to straighten from its relaxed convexly forwardly curved configuration of FIG. 4, so that the rear face of the trigger lever can be pulled into the dotted line position 242 P, substantially against the front face of the handle 12 . Upon release of the trigger by the user, the natural resilience of the trigger lever 242 unbends it back to its solid line forward position shown in FIG. 4 . Accordingly, the trigger naturally returns forward to its non-operative position without need for a separate return spring.
The trigger arm 251 fixedly carries a thumb 250 (FIG. 4A) intermediate it ends in the housing handle and which interferes with the housing wall adjacent the hole 252 , to prevent the resilient restoring force of the trigger lever 242 from pulling the trigger arm 251 leftwardly (FIG. 4A) out of the housing handle 12 .
A plank-like switch contact support arm 251 (FIGS. 2, 4 and 4 A) protrudes substantially at a right angle from the rear, or bottom, end of the trigger lever 242 and extends upwardly and rearwardly (in FIG. 4) into the lower portion of the handle 12 , loosely through a hole 252 (FIG. 4A) in the opposing bottom wall of the handle. A plate-like electrically conductive contact blade 253 fixedly extends through the thickness of the arm 251 , and has a front portion exposed towards said motor and a rear portion exposed toward the bottom end 164 of the handpiece handle.
A pair of rectangular posts 255 and 256 protrude fixedly into the interior of the handle 12 from the inside of the right housing part 15 , about midway between the drive unit 25 and the housing bottom end 164 (FIGS. 4 A and 4 B). Each post 255 and 256 includes a T-shaped flange 260 extending substantially forward toward the drive unit 25 . Each T-shaped flange 260 defines a pair of oppositely facing grooves 261 (FIG. 4 C).
Electrically conductive, spring-like metal contacts 262 and 263 (FIGS. 4A and 4C) each have a substantially U-shaped foot 264 for reception on the T-shaped flange 260 of the corresponding posts 255 and 256 . The contacts 262 and 263 further each have a substantially rectangular, projecting terminal 265 for telescopic fixing thereon, in electrically connected relation, a corresponding one of the front connectors 175 of the three insulated electrical conductors 171 . The electrical contacts 262 and 263 further have respective, generally L-shaped, plate-like, flexible contact leaves 266 and 267 (FIG. 4 C). The contact leaves 266 and 267 extend toward the drive unit 25 as seen in FIG. 4 A.
Protruding rearwardly from the motor 36 are a pair of electrically conductive contacts 270 and 271 (FIGS. 4 A and 9 ). The contact 271 is a conventional terminal (like those at 224 , 225 and 265 ) for receiving one of the front connectors 175 in fixed and electrically conductive relation thereon.
In contrast, the contact 270 is an elongate, springy rectangular piece, bent intermediate its ends in dog-leg fashion, and angling from the rear end of the motor 36 rearwardly and somewhat rightwardly (in FIG. 4A) to a free end portion spaced near the contact leaves 266 and 267 .
Gradual pressing of the trigger lever 242 toward the handle housing (rightwardly in FIGS. 4 and 4A) moves the arm 251 and hence the contact blade 253 progressively further into the handle 12 through a series of positions, three of which are indicated in broken lines at 253 A, 253 B and 253 C in FIG. 4 A.
The free (rightward in FIG. 4A) end of the arm 251 is beveled at 272 to help it ride over the contacts 266 and 267 as the trigger lever 242 is sequentially squeezed more and more toward the handle 12 . The arm 251 is progressively resiliently bent, like a leaf-spring, as its free end rides over the fixed contacts 266 and 267 , to firmly press its contact blade 253 against the latter.
Thus, as the trigger lever 242 is pressed toward the handle 12 , the beveled free end of the arm 251 rides over the contact leaf 266 past its dotted line position 253 A and toward its dotted line position 253 B. As the free arm end approaches position 253 B, the contact blade 253 slides into electrical contact with the contact leaf 266 and the motor contact 270 to establish electrical connection therebetween. The motor contact 270 resiliently bends to allow continued travel of the contact blade 253 and arm 251 further into the handle, as indicated in dotted line at 270 B, and to press firmly against the contact blade 253 . Given only a light pull on the trigger lever 242 , the arm 251 and contact blade 253 tend to stop in the position indicated in dotted lines at 253 B, by reason of the free end of the arm 251 colliding with the contact leaf 267 . In this “B” position, electric current is fed to the motor 36 only from half the battery collection, namely batteries B 1 , B 2 , B 3 and B 4 in FIG. 22 A. The motor 36 thus runs at only a preselected fraction of its full speed and the pump unit 100 outputs irrigation liquid pulses at a desired frequency and amplitude, which are less than the maximum available. The apparatus is thus operated in its low output mode. The colliding of the free end of the trigger arm 251 with the contact leaf 267 gives tactile feedback to the user, that the low output mode of the handpiece has been selected.
Further pulling in of the trigger lever 242 by the user causes the beveled free end of the arm 251 to bend rightwardly (FIG. 4A) the contact leaf 267 to a dotted line position indicated at 267 C, allowing the free end of the arm 251 to override the contact leaf 267 , such that the contact blade 253 moves into its “full-pull” dotted line position 253 C and further bends the motor contact 270 its dotted line position 270 C. In this final position, the contact blade 253 establishes electrical contact between the motor contact 270 and the contact leaf 267 , thereby applying the full series voltage of all eight of the batteries B 1 -B 8 to the motor 36 to operate the latter at its full speed and thereby drive the pump unit 100 at its full output, namely to provide irrigation liquid pulses out of the pump unit 100 at maximum pulse amplitude and frequency.
When the user releases the trigger lever 242 , the resiliently bent trigger lever 242 , due to its inherent resilience, springs back from its fully pulled-in position indicated in broken lines at 242 P, to its solid line rest position indicated at 242 (FIG. 4 A).
Suction Hose
A flexible suction hose 280 (FIGS. 2 and 3) is led along within the housing (within the lower part of the housing in FIG. 3) past the drive unit 25 and pump unit 100 . The above-mentioned clamp plate 165 includes a tubular structure molded thereinto and defined by a forward nipple 282 in the handle 12 and, in coaxial fluid communicating relation therewith, a rearward nipple 283 which extends rearwardly out of the bottom end 164 of the handpiece handle 12 . The rear end portion 281 of the suction hose 280 is sealingly and fixedly telescoped over the front nipple 282 . A conventional flexible hose, not shown, is conventionally and sealing telescopable over the rear nipple 283 for connecting same to a conventional suction source, as schematically indicated at SS in FIG. 3 .
The front end portion 284 of the suction nose 280 is sealingly telescoped over a rearward opening nipple 285 on a short suction conduit 286 (FIGS. 2, 3 , 16 , 17 and 18 ). The suction conduit 286 (FIG. 18) is fixed side by side, in piggyback fashion, on the periphery of the irrigation liquid conduit 143 and hence is a part of (preferably an integral plastic molded part of) the bellows housing 104 .
The clamp plate 165 serves several purposes. It provides a suction hose connection, bears on the irrigation liquid hose where it enters the handpiece housing, and helps align the rear (rightward in FIG. 4) end wall portions of the housing halves as they are assembled together, and in so doing, is itself fixed on the housing. In addition, the clamp plate 165 is of one piece, preferably a plastic molding, and is partially recessed into the handpiece so that it does not make the handpiece look any bigger.
Tip Unit
A tip unit 291 (FIGS. 8, 8 A and 8 B) is releasably fixable on the front end of the handpiece 10 and extends forward therefrom for applying irrigation liquid pulses and/or suction to a surgical site indicated schematically at SU in FIGS. 8 and 8B. The tip unit 291 (FIG. 8) comprises a coupling 292 , a front cover 293 fixed to the front of the coupling 292 , and an elongate hollow wand 294 extending forwardly from the coupling and front cover for aiming at a surgical site SU. The coupling 292 , cover 293 and wand 294 are preferably one piece molded plastic units. The wand 294 is preferably of clear plastics material.
The tip unit 291 , and more specifically the coupling 292 , is releasably fitted in fluid tight relation to the front of the bellows housing 104 of the pump unit 100 and is releasably latched within the open front end of the handpiece housing barrel 13 as hereinafter discussed.
More particularly, the coupling 292 (FIG. 8) comprises a shallow, forward opening cup 295 having a flat base wall 296 from which forwardly extends a shallow peripheral wall 297 , thereby defining a forward opening recess 300 . Coaxial irrigation liquid nipples 301 and 302 extend fixing rearwardly and forwardly, respectively, from the base wall 296 and together define a coaxial bore 303 therethrough and through the base wall 296 . The rear nipple 301 is snugly but slidably receivable rearwardly into the open front portion of the liquid outlet conduit 143 of the bellows housing 104 . An O-ring 304 seats in an annular groove outward facing on the rear nipple 301 and sealingly engages the interior of the liquid outlet conduit 143 to prevent irrigation liquid leakage therebetween.
The wand 294 includes a coaxial, relatively small diameter, irrigation liquid outlet tube 305 which at its rear end is telescoped fixedly and sealingly within the bore 303 of the front and rear nipples 301 and 302 for receiving a pulsed flow of irrigation liquid from the irrigation liquid outlet conduit 143 of the bellows housing 104 .
The coupling 292 further includes a suction nipple 306 fixedly extending rearward from the base wall 296 in spaced parallel relation with the irrigation liquid nipple 301 . The suction nipple 306 is snugly insertable rearwardly coaxially into the front opening suction conduit 286 of the bellows housing 104 . An O-ring 310 is axially sandwiched between the rear end of the suction nipple 306 and a front facing annular step 311 at the rear end of the suction conduit 286 to prevent leakage therebetween.
The coupling 292 further includes a leaf spring-like, generally U-shaped latch arm 312 which extends rearward from the peripheral portion of the base wall 296 , curves radially outwardly and forwardly, and extends forward past the front cover 293 , in radially outwardly spaced relation from the wand 294 . A wedge-shaped, transverse ridge 313 on the exterior base of the latch arm 312 is approximately centered between the front and rear ends of the latch arm. A circumferentially extending, radially inward protruding rib 314 (FIGS. 2, 3 and 8 ) on the interior face and at the open front end of the right housing part 15 (at the front end of the barrel 13 ) opposes the latch arm 312 , immediately ahead of the ridge 313 , with the tip unit 291 installed on the front end of the handpiece 10 as shown in FIG. 8 . The ridge 313 has a front facing step which abuts interferingly with the housing rib 314 to releasably block removal of the tip unit from its installed condition shown in FIG. 8 . To remove the tip unit from the front end of the handpiece, the user simply presses radially inward against the forward protruding end portion 315 of the springy latch arm 312 , sufficient to radially inward displace the ridge 313 out of interfering relation with the rib 314 and thereby unlatch the tip unit from the front end of the handpiece. This allows forward removing the tip unit 291 from the open front end of the handpiece barrel 13 and removing of the irrigation liquid and suction nipples 301 and 306 from the liquid outlet conduit 143 and suction conduit 286 of the bellows housing 104 .
The tip unit 291 , or any alternative tip unit having a substantially identical coupling and front cover, can be installed operatively on the front end of the handpiece 10 by inserting same into the open front end of the handpiece barrel 13 so that the nipples 301 and 306 enter the liquid and suction conduits 143 and 286 respectively, to their position shown in FIG. 8 . During this installation, the forward facing slope of the wedge cross-section transverse ridge 313 slides rearwardly past the housing rib 314 , bending the springy latch arm 312 radially inward as generally indicated by the arrow L in FIG. 8, so that the wedge cross-section ridge 313 can snap rearwardly past the rib 314 at the open front end of the housing barrel 13 . Thus, the tip unit 314 can be slid axially into the front end of the barrel 13 and upon reaching its innermost position latches itself against unintended removal. In its installed condition of FIG. 8, the tip unit is substantially rigidly fixed with respect to the front end of the bellows housing 104 and hence with respect to the handpiece barrel 13 .
The front cover 293 (FIG. 8) comprises a plate 320 which extends radially of the wand 294 and of the length axes of the barrel 13 and the pump unit 100 . The peripheral shape of the plate 320 conforms to the cross-sectional shape of the front end of the barrel 13 , so that the perimeter of the plate 320 is substantially flush with the outer periphery of the open front end of the barrel 13 , and so that the plate 320 effectively covers the open front end of the barrel 13 . The peripheral shape of the plate 320 and cross-sectional shape of the front end of the barrel 13 in one embodiment is generally D-shaped, with a generally flat underside and a convexly curved top and sides. The plate 320 is not intended to seal the open front end of the barrel 13 and so need not tightly abut same. Since the peripheral wall 297 of the cup 295 fits easily within the open front end of the barrel 13 , the plate 320 extends radially outwardly beyond the cup 295 , as seen in FIGS. 8, 8 A and 8 B.
The front cover 293 includes an annular flange 322 extending axially rearwardly therefrom, radially snugly into the cup 295 of the coupling 292 to bottom rearwardly and sealingly against a resilient gasket 321 which is disposed against the front face of the base wall 296 of the cup 295 . Respective holes in the gasket 321 loosely surround the front nipple 302 and leave fully open the communication between the interior of the suction nipple 306 and the interior of the cup 295 . The front cover 293 further includes a further annular flange 323 extending fixedly and forwardly from the plate 320 in coaxial alignment with the through hole 324 in the plate 320 .
The rearward annular flange 322 of the front cover 293 is fixedly secured within the cup 295 of the coupling 292 by any convenient means, for example by snap fit connectors on the opposing faces of such flange 322 and the peripheral wall 297 of the cup 295 . For example, the cup peripheral wall 297 may be provided with several circumferentially spaced rectangular holes 325 (FIGS. 8A and 8B) for snap fit reception therein of small radially outward extending protrusions schematically indicated at 326 on the outside of the rearward annular flange 322 .
The wand 294 further includes a relatively large diameter elongate suction tube 330 (FIGS. 8A and 8B) which loosely coaxially surrounds the irrigation liquid outlet tube 305 (FIG. 8) and extends substantially to the front end of the latter. The rear end portion 331 of the suction tube 330 is radially enlarged to provide a radially shallow, axially elongate flange protruding radially outward therefrom and which is axially trapped between the plate 320 and the gasket 321 backed by the base wall 296 . This serves to rigidly fix the suction tube 330 with respect to the coupling 292 and front cover 293 . A port 332 in the sidewall of the suction tube 330 near its rear end communicates with a loosely surrounding annular chamber 333 defined between the plate 320 and base wall 296 of the front cover 293 and coupling 292 respectively.
The front end of the irrigation liquid tube 305 is held coaxially fixed within the front end portion of the surrounding suction tube 330 by any convenient means, such as radial, circumferentially spaced, webs 334 (FIG. 8 ). Accordingly, with a tip unit 291 , of the general type above described, installed on the front end of the handpiece, as shown in FIG. 8, irrigation liquid pulses from the pump 100 pass forwardly within the liquid tube 305 and are projected from the front (left in FIG. 8) end thereof, as schematically indicated by the arrows PL. At the same time, liquid and particulate debris at the surgical site SU are drawn into the front (left in FIG. 8) end of the suction tube 330 , pass rearwardly along the length thereof, through the port 332 into the chamber 333 and rearwardly through the nipple 306 and suction nipple 285 .
With the exception of a few components such as the motor 44 , the various electrically conductive contacts, the elongate insulated conductors, the various seal rings (for example 105 , 154 , 304 and 310 , the gasket 321 , as well as the suction and irrigation liquid hoses, the remaining major components, while possibly manufacturable of a variety of materials, are economically manufacturable of available molded plastics materials. For example, the valve member 131 may be of rubber or a synthetic substitute or similar resilient plastic. Similarly, the bellows 101 is preferably molded of a suitable resilient plastic material capable of the bellows expansion and contraction movements shown in the drawings. The trigger unit 240 and the latch arm 312 , while of substantially rigid plastics material, are elastically bendable to the extent required to suit the present description. Similarly, components to be snap-fitted together are substantially rigid but have sufficient resilience to permit the required described snap fitting.
The present invention can be constructed at relatively low cost and is thus practically manufacturable as a disposable tool, both the handpiece 10 itself and the accompanying electric power supply unit 190 being disposable after use with a single surgery patient.
OPERATION
The apparatus is quickly and easily assembled. The drive unit 25 (FIG. 12) is assembled by, in effect, “dropping in” elements in proper sequence into the right (lower in FIG. 12) shell 31 and covering same with the other shell 30 . More particularly, output gear 60 , face gear 54 and motor 36 (with attached pinion gear 53 and electric contacts 270 and 271 ) are “dropped” into their respective locations in the upturned shell part 31 , in that sequence. The rectangular shaft 61 , topped by the eccentric member 62 , drops into the corresponding hole in the output gear 60 and the link member 51 drops onto the eccentric member. The other shell part 30 is then snap fitted over the filled shell part 31 , completing the drive unit 25 .
The pump unit 100 is assembled by coaxially telescoping together its elements shown in FIG. 18 and then plugging into the inlet port 146 (FIG. 19) the elbow 151 with the O-ring 154 and hose 160 assembled thereon.
The stub 120 (FIG. 18) of the drive unit 100 can then be snapped into the slot 122 of the drive unit fork 71 (FIG. 2) to connect the drive unit 25 operatively to the pump unit 100 . The suction hose 280 can then be connected to the pump unit nipple 285 and to the nipple 282 on the clamp plate 165 . Thereafter, the two assemblies above described can be laid into the rightward (FIG. 2) housing part 15 in the following order, namely liquid hose 160 (FIG. 4 ), drive unit 25 and pump unit 100 (FIG. 3) and, last, suction hose 280 and clamp plate 165 .
The trigger unit 240 is then placed, with its rightward (FIG. 2) pivot stub 243 located in the corresponding boss 244 in the rightward housing part 15 , and its arm 251 inserted through the hole 252 (FIG. 4A) into the interior of the handle portion of the rightward housing part 15 , as seen in FIGS. 4 and 4A. The trigger arm 251 is “covered” by the rear portion 281 of the suction hose 280 in FIG. 3 . The electrical contacts 262 and 263 are placed on their respective posts 255 and 256 in the rear portion of the rightward housing part 15 and the three forward electrical connectors 175 are secured respectively to the mentioned contacts 262 and 263 and the motor contact 271 (FIG. 4 A). Thereafter, the leftward (FIG. 2) housing part 14 can be snap fitted to the rightward housing part 15 to close same and enclose the above mentioned apparatus, shown in FIG. 3, therein.
In the thus assembled handpiece, the drive unit is fixedly located by engagement of its drive axis bosses 84 and 85 (FIG. 5) in corresponding bosses in the housing parts 14 and 15 (see for example at 96 in housing part 15 in FIG. 2 ). Location of the drive unit 25 is assisted by the ribs 95 within the housing parts 14 and 15 and by snug resilient engagement of the drive unit 25 by the hoses 160 and 280 which flank it.
The drive unit shell 26 is configured to maintain the proper tolerances between meshing gears and related parts. Location of all the drive unit parts in the drive unit shell 26 reduces the need to maintain close tolerances in the larger and less specialized handle housing 11 . Even the housing tolerances, for locating the pump unit 100 with respect to the drive unit 25 in the housing 11 , need not be close since the bellows 101 are flexible enough to bend or otherwise distort to absorb minor mis-alignment or angulation of the reciprocation axis of the link member 51 with respect to the length axis of the pump unit 100 . Indeed, the ribs 95 in the housing 11 permit pivoting of the drive unit 25 about the axis of the bosses 96 to allow the drive unit 25 and pump unit 100 to settle into their own working relative orientation. Accordingly, the precision in the handpiece housing 11 can be concentrated in aspects of fitting together of the two housing halves.
The electric power supply unit 190 (FIG. 22) is quickly and easily assembled. More particularly, the feet of the respective battery contacts 210 , 211 , 212 (FIGS. 26-28) are slid downward into their respective grooves (FIGS. 23A and 23B) in the pan 192 (FIG. 22) with their protruding toes resiliently gripping the sides of the grooves. The rear connectors 176 are connected to the battery contact fingers 224 and 225 in the order shown in FIG. 22 A. The batteries B 1 -B 8 are then slipped down into the pan in the orientation shown in FIG. 22 and into electrically conductive engagement with the battery contacts 210 , 211 and 212 indicated in FIG. 22 A. The rear portion of the liquid hose 160 is laid atop the batteries as indicated in FIG. 23, with the square flange 182 nonrotatable in the boss 235 , and the cover 193 is snap fitted atop the liquid hose 160 and battery filled pan 192 , as shown in FIG. 23, to complete assembly of the power supply unit. The cap 185 is pressed onto the sharpened tip 184 to protect it prior to use.
The result is a disposable pulsed irrigation handpiece unit which is entirely self-contained, including its own power supply, and which is ready for use upon having its sharpened tip 184 plugged into a conventional irrigation liquid supply bag or the like, and a conventional manner.
It should be noted that virtually the entire handpiece 10 and power supply unit 190 can be assembled without need for any adhesives, the parts going together with friction or snap fits or, in the case of the joinder of the bellows housing 104 to the bellows 100 and elbow 151 , by being held together by surrounding structure which in turn is snap fitted together. This greatly eases and speeds assembly. A minor exception is that the fitting 180 is here adhesively fixed to the hose 160 .
To use the handpiece assembly in surgery, the cap 185 (FIG. 23) is removed from the pointed tip 183 , which is then plugged into a standard output fitting on a conventional irrigation liquid supply bag. The power supply unit 190 , being fixed to the rear end of the irrigation liquid hose 160 , can be allowed to simply hang from the irrigation liquid supply bag (not shown but schematically indicated at S in FIG. 22 ). By providing a substantial length of irrigation liquid hose 160 (for example 10 feet), the liquid supply bag S and power supply unit 190 can be located well out of the way of the surgical team during use of the handpiece 10 at the surgical site. Even then, the power supply unit 190 is compact as compared to the adjacent conventional irrigational liquid supply bag (being very little larger than the eight conventional double AA batteries that it houses).
If suction will be desired at the surgical site, the handpiece nipple 283 (FIG. 3) can be connected by a conventional hose not shown to a conventional suction source SS (FIG. 3 ).
A variety of tip units 291 of differing characteristics (e.g. differing irrigation liquid spray patterns, etc.) may be made available for alternative mounting on the handpiece 10 . One example is shown in FIGS. 8, 8 A and 8 B.
In any event, the user selects a tip unit 291 having a wand 294 of desired configuration, and rearwardly inserts its coupling 292 into the front end of the handpiece 11 . More particularly, the nipples 301 and 306 of the tip unit are inserted coaxially rearwardly, in sealed relation (see FIG. 8) in the conduits 143 and 286 respectively of the bellows housing 104 . The resilient latch arm 312 enters the barrel 13 of the handpiece housing 11 adjacent to the bellows housing 104 until the plate 320 of the front cover 293 abuts the front end of the handpiece housing barrel 13 . In the last part of this tip installation movement, the wedge shaped ridge 313 (FIG. 8) on the latch arm 312 snaps past the rib 314 of the housing barrel 13 to positively prevent forward removal of the tip unit from the handpiece.
To use the apparatus for irrigation of a surgical site, the user grips the handpiece, either by the handle 12 , in a pistol-like manner, or where the barrel 13 joins the handle 12 , in a wand like manner. In either position, the user has one or more fingers that can bear on and press inwardly the trigger lever 242 from its inoperative rest position shown in solid line in FIG. 4A forward and through its low speed and high speed positions indicated in broken lines at 253 B and 253 C in FIG. 4 A. In the first operative position 253 B, the blade 253 connects the low speed (here six-volt) contact 266 to the motor contact 270 . On the other hand, in the fully depressed condition of the trigger, indicated at 253 C, the blade 253 connects the high speed, 12 volt contact 267 with the motor contact 270 . Accordingly, the user can select between “off”, lower power pulsing and high power pulsing.
In one embodiment pump stroke was about ¼″. In one embodiment shown, the motor speed was about 15,000 rpm and the speed reduction afforded by the transmission was about 15-1, providing the eccentric with about 1,000 rpm speed.
Depending on the flow resistance of the particular tip unit attached to the handpiece, the liquid pulse frequency may change. In one example, a handpiece according to the invention produced about 1200 pulses per minute, dispensing about 1600 ml per minute of irrigation liquid in about 1.3 ml liquid pulses. The positive drive of the pump unit by the drive unit and the location of the pump unit, near the front end of the barrel 13 and in direct engagement with the tip unit, provides liquid pulses at the output of the tip unit which have sharp rise and fall slopes. Thus, the relationship of liquid pulse amplitude to time approximates a square wave form, more so than for example, the aforementioned device of U.S. Pat. No. 5,046,486. Further, the force applied to the pulses by the present apparatus is higher (somewhat above one Newton) than in that prior art device, at the full power position of the trigger.
In one embodiment according to the invention, a tab 316 (FIGS. 1 and 8B) extends forward from the front plate 320 of the front cover 293 , on the opposite side of the wand 294 from the latch arm 312 . To release the latch arm 312 from the housing 11 , the user can thus simply simultaneously grip with opposite fingers and pinch toward each other the latch arm 312 and tab 316 . In other words the tab 316 provides base toward which to pinch, or pull, the latch arm 312 to release the tip unit 291 from the handpiece 11 .
In the present invention, the liquid and suction nipples of the tip unit connect directly to the pump unit 100 , and do not contact any part of the handpiece housing 11 . Accordingly, neither the pump unit 100 nor tip unit 291 need fit with close tolerances the handpiece housing 11 . The connection of the tip unit to the handpiece housing is merely to latch the tip unit against loss from the handpiece housing and to casually cover the open front end of the handpiece housing. Accordingly, the liquid tight fit is between the nipples of the tip unit and conduits of the pump unit, not with the housing.
Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.
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A pulsed irrigation handpiece comprises a pulsed irrigation liquid outlet for applying liquid pulses to a surgical site, a pump unit reciprocatingly driveable for pumping pulses of irrigation liquid through the outlet, an electric powered drive unit for reciprocatingly driving the pump unit, and a housing containing the pump and drive units. A irrigation inlet hose leads from the pump unit out of the handpiece housing and is connectable to a remote irrigation liquid source. An irrigation inlet hose adjacent the remote end thereof and electric conductors extending along the irrigation inlet hose transfer electric power from the supply unit to the drive unit in the handpiece. Removable tips are alternatively removably attachable to the irrigation liquid outlet adjacent the front end of the handpiece.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional and continuation-in-part of Ser. No. 10/828,404, now U.S. Pat. No. 7,318,275, filed Apr. 19, 2004, and entitled “Method of Remanufacturing a Compressor” which is a divisional of Ser. No. 10/331,793, now U.S. Pat. No. 6,739,851, filed Dec. 30, 2002, and entitled “Coated End Wall and Method of Manufacture”, the disclosures of which are incorporated by reference in their entireties herein as if set forth at length.
BACKGROUND OF THE INVENTION
[0002] This invention relates to compressors, and more particularly to screw compressors.
[0003] Screw-type compressors are commonly used in refrigeration applications. In such a compressor, intermeshed male and female lobed rotors or screws are driven about their axes to pump the refrigerant from a low pressure inlet end to a high pressure outlet or discharge end. The rotors are typically supported by bearings on inlet and outlet sides of their lobed working portions.
[0004] The clearance between the discharge end faces of the rotors and the adjacent housing surface influences compressor efficiency. A tight or small clearance improves efficiency by reducing internal leakage. Maintaining a tight clearance may require precision machining and alignment of these surfaces. A tight clearance, however, risks metal-to-metal contact between the surfaces which may cause damage. Accordingly, for controlling leakage while maintaining metal-to-metal clearance, it is known to utilize a relatively soft coating on the housing surface to partially fill the metal-to-metal clearance. Should a rotor contact the coating, the coating will be conformed and/or abraded without substantial damage to metal components or performance. Various plastically conformable coatings are known, including, iron phosphate, magnesium phosphate, nickel polymer amalgams, nickel zinc alloys, aluminum silicon alloys with polyester, and aluminum silicon alloys with polymethylmethacrylate (PMMA). These may be applied by appropriate methods, including, for example, thermal spraying, physical vapor deposition (PVD), chemical vapor deposition (CVD), and aqueous deposition.
[0005] In an exemplary method of manufacture of such a compressor, the discharge end housing surface (e.g., of an outlet casing element of the housing assembly) is precision machined. The coating is then applied and the coating is machined to a desired final thickness. In this example, the precise thickness is required to provide precision in a subsequent end clearance setting process. In that process, the rotors are assembled and placed in a rotor housing portion of the housing assembly. The outlet casing is installed as are the bearings on the discharge end of the rotor shafts. Shims are inserted to cooperate with the thrust and radial bearings to constrain the longitudinal movement of the rotors relative to the outlet casing. The rotors are pulled against the outlet casing to zero a measurement tool. The rotors are then pushed away until restrained by their respective thrust bearings. The displacement is measured and this determines the clearance upon final assembly. If each measured clearance is within specified limits, the compressor may be further assembled. If not, for any rotor outside the limits, a different shim combination may be selected to bring the measured clearance more in line with the specified clearance and the process repeated.
BRIEF SUMMARY OF THE INVENTION
[0006] A compressor has a housing assembly and at least one rotor held by the housing assembly for rotation about a rotor axis. The rotor has a first face and a first housing element has a second face in facing spaced-apart relation to the first face of the rotor. The housing has a coating on the second face and a plurality of inserts protruding from the second face into the coating.
[0007] Advantageously, the housing is made of a first material and the inserts consist essentially of a material that is more malleable than the first material.
[0008] Another aspect of the invention involves a method of manufacture, remanufacture, or repair of a compressor. The compressor has a rotor with a working portion having a first end face. A housing assembly carries the rotor for rotation about a rotor axis. The housing assembly has a first housing element having a first surface facing the first end face. The method includes positioning one or more spacer elements from the first housing element. The one or more spacer elements are machined. A coating is applied over the first surface around the one or more spacer elements.
[0009] In various implementations, there may be a plurality of such spacer elements (e.g., between three and five). The machining may provide coplanarity of first end surfaces of the spacer elements. The coating may be plastically deformed to a thickness associated with a height of the spacer elements (e.g., above the housing first surface). The thickness may be between 40 and 250 μm. The plastic deformation may consist essentially of compressing (e.g., with the rotor or with a flat element). The positioning may comprise press fitting. Old spacer elements may be removed before inserting the spacer elements. The rotor may be a screw-type male rotor and the compressor may further include at least one screw-type female rotor and meshed with the male rotor.
[0010] Another aspect of the invention involves a method of manufacture, remanufacture, or repair wherein a coating is applied over a housing first surface around a number of spacers protruding from the housing. The coating is plastically deformed by compressing.
[0011] Another aspect of the invention involves a method of manufacture, remanufacture, or repair including one or more steps for providing at least one spacer element protruding from a housing first element. A coating is applied in one or steps over a first surface of the first housing element. The applied coating is precompressed in one or more steps.
[0012] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a partially schematic longitudinal sectional view of a compressor.
[0014] FIG. 2 is an enlarged view of a portion of the compressor of FIG. 1 .
[0015] FIG. 3 is an enlarged view of a portion of the compressor of FIG. 2 .
[0016] FIG. 4 is an end view of a female rotor working portion.
[0017] FIG. 5 is a longitudinal sectional view of an outlet casting.
[0018] FIG. 6 is a view of the casting of FIG. 5 after a recess machining.
[0019] FIG. 7 is a view of the casting of FIG. 6 after a coating.
[0020] FIG. 8 is a view of the casting of FIG. 7 after deformation of the coating.
[0021] FIG. 9 is an end view of the casting of FIG. 8 .
[0022] Like reference numbers and designations in the various drawings indicate like elements.
DETAILED DESCRIPTION
[0023] The invention relates to compressors and methods for manufacture, remanufacture and/or repair. Spacer elements are associated with the application of a coating to one or more select surfaces of the compressor to improve such manufacture, remanufacture and/or repair. FIG. 1 shows a compressor 20 having a housing assembly 22 containing a motor 24 driving three rotors 26 , 28 , and 30 having respective central longitudinal axes 500 , 502 , and 504 . In the exemplary embodiment, the rotor 26 is centrally positioned within the compressor and has a male lobed body or working portion 32 enmeshed with female lobed bodies or working portions 34 and 36 of the female rotors 28 and 30 . Each rotor includes shaft portions (e.g., stubs 40 , 41 ; 42 , 43 ; and 44 , 45 ( FIG. 2 ) unitarily formed with the associated working portion 32 ; 34 ; and 36 ) extending from first and second ends of the working portion. Each of these shaft stubs is mounted to the housing by one or more bearing assemblies for rotation about the associated rotor axis.
[0024] In the exemplary embodiment, the motor is an electric motor having a rotor 50 and a stator 52 . A distal portion 54 of the first shaft stub 40 of the male rotor 26 extends within the stator 52 and is secured thereto so as to permit the motor 24 to drive the male rotor 26 about the axis 500 . When so driven in an operative first direction about the axis 500 , the male rotor drives the female rotors in opposite directions about their axes 502 and 504 . The resulting enmeshed rotation of the rotor working portions tends to drive fluid from a first (inlet) end plenum 56 to a second (outlet/discharge) end plenum 58 while compressing such fluid. This flow defines downstream and upstream directions. The exemplary housing assembly 22 includes a rotor housing 60 having a transverse web 62 in which the rotor inlet end shaft stubs are mounted via appropriate bearings, seals and the like. The rotor housing 60 extends upstream from the web to substantially contain and surround the rotor working portions. The rotor housing 60 extends upstream to mate with a motor casing 64 which cooperates with the rotor housing to support and contain the motor 24 . At its downstream end, the rotor housing 60 mates with an outlet casing 70 . For each of the rotors, the outlet casing has a bearing compartment carrying a series of bearing assemblies (described below) for rotatably mounting the downstream (outlet/discharge end) shaft stub of such rotor. The outlet casing further includes an upstream-facing end surface 72 ( FIG. 2 ) in close facing proximity to the discharge end faces (surfaces) of the rotor working portions. A bearing cover plate 78 is centrally mounted to the outlet casing to cover the bearing compartments. A discharge housing 80 ( FIG. 1 ) is mounted surrounding the bearing cover plate. Exemplary rotor and housing materials are metals. Exemplary housing components are made of gray iron. Exemplary rotors are made of ductile iron and/or steel.
[0025] FIG. 2 shows further details of the mounting of the outlet end shaft stubs of the male and female rotors. Aligned in an inlet-to-outlet direction, the male rotor has a radial bearing 90 , a thrust bearing 92 , and a counterthrust bearing 94 . Along the shaft stub between the bearing 90 and the discharge end face 100 of the rotor working portion, a floating bushing seal 102 is carried by the outlet casing to engage the shaft and an axial seal 104 is carried by the outlet casing to engage the face 100 . The clearance between the surface 72 and the face 100 is determined by the cooperation of the bearings 90 , 92 , and 94 along with any spaces and/or shims. A rotor cap 112 , secured to the end of the shaft stub, bears against the outlet end rim of the inner race of the third bearing 94 to capture the sandwich of the three inner races. A bearing retainer 114 has an inlet end rim engaging a preload spring 116 which in turn engages the outer race of the third bearing 94 and an outlet end rim engaging the bearing cover plate 78 .
[0026] The outlet end shaft stub of each female rotor has, aligned in an inlet-to-outlet direction a radial bearing 120 , a thrust bearing 122 , and a counterthrust bearing 124 . A floating bushing seal 126 engages the shaft in a reduced diameter base portion of the bearing compartment. At its inlet end rim, the inner race of the bearing 120 contacts a shoulder of the shaft stub. A rotor cap 140 , secured to the end of the shaft stub, bears against the outlet end rim of the inner race of the bearing 124 to capture the sandwich of three inner races. A bearing retainer 142 has an inlet end rim engaging the outer race of the bearing 124 and an outlet end rim engaging a preload spring 143 which in turn engages the bearing cover plate.
[0027] FIG. 3 further shows, in exaggerated thickness, a coating 200 on the surface 72 and a plurality of pins 220 mounted in bores 222 in the outlet casing and protruding from the surface 72 to extend into the coating. In the illustrated exemplary embodiment, four of the pins lie along the common plane of the rotor axes, whereas others are similarly oriented but lie away from the plane. Of these four pins, each of the outboard pins is associated with one of the female rotors and is positioned with its inlet end face 224 in close facing proximity to an area swept by the portion of the outlet end surface 118 that lies along the female rotor lobes. Each of the inboard pins is similarly positioned relative to one of the female rotors but is also positioned in an area swept by the end surface 100 of the male rotor along its lobes as shown in further detail in FIG. 3 .
[0028] FIG. 3 further identifies a pin length L 1 , a pin diameter D 1 , a coating thickness T 1 , an overall metal-to-metal clearance T 2 , and a metal-to-coating clearance T 3 .
[0029] FIG. 4 shows an exemplary outlet end surface (face) 118 of a female rotor. The face includes portions 250 defined by the ends of the plurality of lobes and a central continuous annular portion 252 inboard of the lobe roots. In the illustrated embodiment, at the outlet end surface, the shaft stub has a diameter D 2 , the central portion 252 has a root diameter D 3 and the lobes have an outside diameter D 4 .
[0030] In an alternate pin arrangement each pin associated with the female rotor is positioned to fall entirely under the root diameter D 3 . This permits a minimal number of pins as it guarantees pins will be aligned with the end surface regardless of rotor orientation. Although as few as one pin may be used, three are advantageous for purposes of precise orientation during the clearance setting process. If the pins were entirely positioned to fall between the root diameter D 3 and outside diameter D 4 , then, if it is desired that contact be assured irrespective of orientation during the clearance setting procedure, either particularly broad pins would have to be used (e.g., pins with large D 1 or having sections like an annular segment) or a greater number of pins would have to be used.
[0031] In an exemplary method of manufacture, the pins are installed and their ends machined to provide the desired exposure (e.g., to T 1 ) in the same manufacturing station wherein the surface 72 is machined. The coating is then applied to a thickness of at least T 1 . A flat or other plate may then be pressed down atop the coating until stopped by engagement with the pin end face 224 . The compression advantageously plastically deforms the coating so that, when the plate and compressive forces are removed, the coating will retain a uniform thickness of T 1 coincident with or just slightly greater than the pin exposure. Alternatively, the rotor end faces could be used to plastically deform the coating by pulling the rotors into the coating until stopped by engagement with the pin end faces 224 . This method may be less advantageous as the interlobe area would leave portions of the coating uncompressed unless the rotors were rotated and the process repeated.
[0032] Exemplary material for the pins is brass. Other materials, such as aluminum, bronze, or engineering plastics may alternatively be used. As described below, the pin material is advantageously softer and more malleable or otherwise deformable than that of the rotor so that, upon any rotor-to-pin contact the rotor will remain essentially undamaged, potentially sacrificing the pins.
[0033] Advantageously the coating is of a conformable coating material as are known in the art (e.g., as described above) or may yet be developed. As applied, the coating may have an exemplary thickness between 30 and 500 μm. After initial compression, the exemplary thickness T 1 may well be between 20 and 300 μm. More preferably, such thickness may be between 40 and 250 μm. The exemplary metal-to-coating clearance T 2 may well be between 5 and 100 μm, more preferably such clearance T 2 may be between 10 and 20 μm, leaving a preferred metal-to-metal clearance T 3 between 50 and 270 μm. Exemplary coating processes are described above. Among alternate coating processes are application of pre-formed coating layers (e.g., a peel & stick product with pressure-sensitive adhesive).
[0034] FIGS. 5-9 show an example of an alternate implementation as a retrofit/modification of an existing compressor. Specifically, FIG. 5 shows an existing/baseline outlet casting 70 . For example, the casting 70 may be removed from a compressor in service. Alternatively, the casting may be new (even including in an intermediate stage of manufacture). The exemplary outlet casting 70 is shown with pre-formed bearing compartments, mounting bores, and porting. The casting 70 may be fixtured and a recess/trough 300 ( FIG. 6 ) machined (e.g., with an end mill or other tool) in the initial end surface 72 . The machining leaves the trough having a base surface portion 72 ′ recessed below the intact surface 72 by a depth D. In a subsequent stage, a coating 320 ( FIG. 7 ) is applied in the recess/trough 300 to an initial thickness T 4 , leaving the exposed surface 322 of the coating proud of the surface 72 . Prior to application of the coating 320 , various features may be masked (e.g., the bearing compartments, ports, and intact portion of the surface 72 surrounding the recess).
[0035] After coating application, the coating 320 may be compressed. FIG. 8 shows a flat plate 330 compressing the coating so that the surface 322 becomes flush with the intact surface 72 . A portion of the plate 330 laterally beyond the coating may register with the intact surface 72 to ensure precise deformed coating thickness. In alternative implementations, there may be slight undercompression or overcompression. For example, an undercompression may involve recessing a portion of the surface 332 of the plate 330 coextensive with the coating 320 . An overcompression may involve having that surface portion proud of the portion engaging the surface 72 . The compression may be to a final thickness T 5 which may be coincident with the depth D and similar to the thickness T 1 identified above.
[0036] FIG. 9 shows a lateral perimeter 340 of the recess/trough 300 . FIG. 9 also shows a perimeter 342 of a baseline coated area of the baseline casting 70 . Hatching shows coating extent rather than sectioning. Whereas much of the perimeter 342 falls along the rotor bores (boundary of rotor lobe sweep), the adjacent perimeter 340 falls slightly therebeyond.
[0037] One or more embodiments of the present 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, it might be applied to various compressors including open-drive compressors, single-rotor screw compressors, or other multi-rotor screw compressors. Accordingly, other embodiments are within the scope of the following claims.
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A compressor has a housing assembly and at least one rotor held by the housing assembly for rotation about a rotor axis. The rotor has a first face and a first housing element has a second face in facing spaced-apart relation to the first face of the rotor. One or more spacer elements are positioned from the first housing element. The spacer elements are machined. A coating is applied over the first surface around the one or more spacer elements.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a U.S. National Stage filing under 35 USC §371 of International Patent Application No. PCT/JP2013/070337 filed on Aug. 9, 2013. This application also claims priority under the Paris Convention to Japanese Application No. 2011-266732, filed on Dec. 6, 2011.
TECHNICAL FIELD
The present invention relates to a fluid-pressure apparatus having a pair of gears whose tooth surfaces mesh with each other.
BACKGROUND ART
As a fluid-pressure apparatus as mentioned above, a hydraulic pump which rotates a pair of gears by an appropriate drive motor and pressurizes an operation fluid by the rotational motions of the gears and discharges the pressurized operation fluid, and a hydraulic motor which rotates gears by introducing a previously pressurized operation fluid therein and uses rotational forces of rotating shafts of the gears as a power are conventionally known.
Such fluid-pressure apparatuses have a problem of operational noise generated by meshing of gears, a problem of noise generated by discontinuous change of the volume of the liquid confined between tooth surfaces of the meshing gears, and the like. In order to reduced such noise, conventionally a fluid-pressure apparatus using a pair of gears having a theoretical tooth profile which prevents the occurrence of a gap between tooth surfaces of the gears meshing with each other has been suggested (see the Unexamined Patent Application (Translation of PCT Application) Publication No. 2010-521610).
FIGS. 8 to 11 show the fluid-pressure apparatus disclosed in the Unexamined Patent Application (Translation of PCT Application) Publication No. 2010-521610, specifically, an oil hydraulic device. It is noted that, although the Unexamined Patent Application (Translation of PCT Application) Publication No. 2010-521610 does not disclose the whole configuration of the oil hydraulic device, FIGS. 8 and 9 shows also the whole configuration thereof.
As shown in FIGS. 8 and 9 , an oil hydraulic device 1 has a housing 2 having a hydraulic chamber 4 formed therein, a pair of helical gears 20 ′, 23 ′ (hereinafter, simply referred to as “gears”) inserted in the hydraulic chamber 4 in a state where their tooth portions mesh with each other, and bushes 30 , 32 as two support members which are inserted in the hydraulic chamber 4 in a state of being in contact with both end surfaces of the pair of gears 20 ′, 23 ′ to support the pair of gears 20 ′, 23 ′.
The housing 2 comprises a body 3 in which the hydraulic chamber 4 having a space with a substantially 8-shaped cross-section is formed from one end surface to the other end surface thereof, a first flange 8 screwed on the one end surface of the body 3 , and a second flange 11 similarly screwed on the other end surface of the body 3 , and the hydraulic chamber 4 is closed by the first flange 8 and the second flange 11 .
One of the pair of gears 20 ′, 23 ′ is a driving gear 20 ′ and the other is a driven gear 23 ′. The gears 20 ′, 23 ′ respectively have rotating shafts 21 , 24 which are respectively provided to extend in the axial directions of the gears 20 ′, 23 ′ from both end surfaces of the gears 20 ′, 23 ′, and the rotating shaft 21 of the gear 20 ′ has a tapered portion formed on one end portion thereof and a screw portion 22 is formed on the tip of the tapered portion. Further, the pair of gears 20 ′, 23 ′ are, as described above, contained in the hydraulic chamber 4 in a state of meshing with each other, and the outer surfaces of their tooth tips are in sliding contact with an inner peripheral surface 7 of the hydraulic chamber 4 .
The bushes 30 , 32 are metal bearings comprising a plate-shaped member having a substantially 8-shaped cross-section and respectively have two support holes 31 , 33 , and the rotating shafts 21 , 24 of the gears 20 ′, 23 ′ are inserted through the support holes 31 , 33 , and thereby the rotating shafts 21 , 24 are supported to be rotatable. Further, the bushes 30 , 32 are inserted in the hydraulic chamber 4 in a state where the rotating shafts 21 , 24 of the gears 20 ′, 23 ′ are inserted through the support holes 31 , 33 and end surfaces of the bushes 30 , 32 are in contact with the end surfaces of the gears 20 ′, 23 ′. It is noted that the other end surfaces of the bushes 30 , 32 are in contact with of end surfaces of the first flange 8 and the second flange 11 , respectively, and thereby movement of the gears 20 ′, 23 ′ and the bushes 30 , 32 in their axial directions is restricted.
Further, the first flange 8 has an insertion hole 9 formed through which the rotating shaft 21 having the screw portion 22 of the driving gear 20 ′ is inserted, and the driving gear 20 ′ is arranged in the hydraulic chamber 4 in a state where the rotating shaft 21 is inserted through the insertion hole 9 of the first flange 8 and extended to the outside. Further, an oil seal 10 is provided in the insertion hole 9 and the oil seal 10 provides sealing between the insertion hole 9 and the rotating shaft 21 . It is noted that O-rings 12 are respectively interposed between the end surfaces of the body 3 and the first and second flanges 8 , 11 , and the O-rings 12 provide sealing therebetween.
Further, the body 3 has an intake port (intake flow path) 5 , which leads to the hydraulic chamber 4 , bored in one side surface thereof and a discharge port (discharge flow path) 6 , which similarly leads to the hydraulic chamber 4 , bored in another side surface thereof located opposite said side surface with the hydraulic chamber 4 between them. Further, the intake port 5 and the discharge port 6 are provided so that their axes are positioned at the middle between the rotating shafts 21 , 24 of the pair of gears 20 ′, 23 ′.
The pair of gears 20 ′, 23 ′ has such a theoretical tooth profile that their tooth surfaces are continuously and linearly in contact with each other in the axial direction of the rotating shafts 21 , 24 and tooth tips of one of them are brought into contact with tooth bottoms of the other of them as shown in FIGS. 10 and 11 . Thus, due to the contact between the gears 20 ′ and 23 ′, the hydraulic chamber 4 is divided in two, a high-pressure side and a low-pressure side, with the contact portion 26 as a border. The bushes 30 , 32 being in contact with the end surfaces of the gears 20 ′, 23 ′ have a function of preventing leakage of the operation fluid from the high-pressure side to the low-pressure side by the contact between the gears 20 ′ and 23 ′, and therefore, in the oil hydraulic device 1 , the roundness or inclination of edges of the end surfaces of the tooth portions of the gears 20 ′, 23 ′ is set to be as small as possible.
The oil hydraulic device 1 having the above-described configuration can be used as an oil hydraulic pump or an oil hydraulic motor. For example, in a case where it is used as an oil hydraulic pump, appropriate piping which is connected to an appropriate tank for storing an operation fluid therein is connected to the intake port 5 of the housing 2 , and the rotating shaft 21 of the driving gear 20 ′ is driven by an appropriate drive motor, thereby rotating the driving gear 20 ′ in the direction indicated by the arrow R shown in FIG. 11 .
Thereby, the driven gear 23 ′ meshing with the driving gear 20 ′ is rotated in the direction indicated by the arrow R′, the operation fluid in a space 28 between the inner peripheral surface 7 of the hydraulic chamber 4 and the tooth portions of the gears 20 ′, 23 ′ is transferred to the discharge port 6 side by the rotation of the gears 20 ′, 23 ′, and the discharge port 6 side is brought into a high pressure and the intake port 5 side is brought into a low pressure, with the contact portion 26 between the pair of gears 20 ′, 23 ′ as a border.
When the intake port 5 side is brought into a negative pressure in the above-described manner, the operation fluid in the tank is inhaled into the low-pressure side of the hydraulic chamber 4 through the piping and the intake port 5 , and is transferred to the discharge port 6 side by the operation of the pair of gears 20 ′, 23 ′ and thereby pressurized to a high pressure, and the pressurized operation fluid is discharged through the discharge port 6 .
In the above-described manner, the oil hydraulic device 1 functions as an oil hydraulic pump.
Further, according to this oil hydraulic device 1 , since, as described above, the pair of gears 20 ′, 23 ′ have such a theoretical tooth profile that their tooth surfaces are continuously and linearly in contact with each other in the axial direction of the rotating shafts 21 , 24 and the tooth tips of one of them are brought into contact with the tooth bottoms of the other, the above-mentioned noise problems can be solved. Further, since the roundness or inclination of the edges of the end surfaces of the tooth portions is set to be as small as possible and thereby the sealability between the end surfaces of the gears and the end surfaces of the bushes is improved, thereby preventing leakage of the operation fluid from the high-pressure discharge port 6 side to the low-pressure intake port 5 side, high discharge volume (which is volume efficiency and also output efficiency) can be obtained.
SUMMARY OF THE DISCLOSURE
However, while the above-described conventional oil hydraulic device 1 has, as described above, a merit that the noise problems can be solved and high volume efficiency can be obtained, it has a problem that, since the roundness or inclination of the edges of the end surfaces of the tooth portions is set to be as small as possible for obtaining high volume efficiency, when the pair of gears 20 ′, 23 ′ mesh with each other, contact stress tends to concentrate at the edges and the edges are easily damaged due to the contact stress. Particularly, intermediate parts between the teeth tips and the tooth bottoms are regions having a function of transmitting power from the driving gear 20 ′ to the driven gear 23 ′, and because a larger stress acts thereon than on the tooth tips and the tooth bottoms, the intermediate parts are easily damaged. Further, in a case where the pair of gears 20 ′, 23 ′ are helical gears like the oil hydraulic device 1 , as shown in FIG. 10 , the edges have portions where the angle is acute (acute angle portions) 27 a ′ and portions where the angle is obtuse (obtuse angle portions) 27 b ′, and, of these portions, particularly the acute angle portions 27 a ′ are easily damaged. FIG. 12 shows a state where edge portions are damaged as described above. It is noted that the damaged portions are indicated by the reference C.
Further, if, for example, an edge portion is broken as described above, a problem that a broken piece caused by the breaking bites the pair of gears 20 ′, 23 ′ meshing with each other and the tooth surfaces thereof at the biting portion is damaged, that is, the damaged region is expanded is caused, and, in turn, a large abnormal noise occurs or the oil hydraulic device 1 can be brought into a disabled state. Furthermore, it is conceivable that the broken piece caused by the breaking is transferred from the oil hydraulic device 1 to an oil hydraulic equipment connected thereto and the oil hydraulic equipment is damaged by the broken piece.
Further, in a case where an edge portion is broken, the sealability between the edges and the bushes 30 , 32 is reduced, and therefore a problem that the discharge amount of the operation fluid is reduced, that is, volume efficiency is lowered, is caused. This problem is explained with reference to FIGS. 13 to 15 . It is noted that FIGS. 13 and 15 are sectional views showing a state where the bush 30 ( 32 ) is in contact with the end surfaces of the gears 20 ′, 23 ′, and FIG. 13 shows a case where the edges are not broken and FIG. 15 shows a case where an edge portion is broken. Further, FIG. 14 is a sectional view showing a portion where the gear 20 ′ ( 23 ′) is in contact with the bush 30 ( 32 ) and the inner peripheral surface 7 of the body 3 , and shows a case where the edge is not broken.
As shown in FIGS. 13 and 14 , in the case where the edges are not broken, since the roundness or inclination of the edges is set to be as small as possible, a gap 40 between the edges of the gears 20 ′, 23 ′ and the bush 30 ( 32 ) and a gap 41 between the edge portion of the gear 20 ′ ( 23 ′), the body 3 and the bush 30 ( 32 ) is very small, and further viscous resistance acts between the edges of the gears 20 ′, 23 ′, the bush 30 ( 32 ) and the body 3 . Therefore, leakage of the operation fluid through the gaps 40 , 41 between the high-pressure side and the low-pressure side hardly occurs.
On the other hand, if, for example, an edge portion of the gear 20 ′ is broken as shown in FIG. 15 , a gap 40 ′ between the edges of the gears 20 ′, 23 ′ and the bush 30 ( 32 ) is large, and, as for the operation fluid in the vicinity of the edges and the bush 30 , viscous resistance acts between the operation fluid and the edges and between the operation fluid and the bush 30 , whereas, as for the operation fluid away from the edge portions and the bush 30 , such viscous resistance does not act. Therefore, movement of the operation fluid through the gap 40 ′ easily occurs and leakage of the operation fluid from the high-pressure side to the low-pressure side occurs.
Thus, the above-described conventional oil hydraulic device 1 has a structural problem that a rated discharge amount cannot be maintained for a long time, and a problem that the device lacks reliability.
The present invention has been achieved in view of the above-described circumstances and an object thereof is to provide a conventional fluid-pressure apparatus which is quiet and has high output efficiency, the apparatus being capable of maintaining the quietness and the output efficiency for a long time, and having higher reliability than before.
Solution to Problem
The present invention, for solving the above-described problems, relates to a fluid-pressure apparatus comprising:
a pair of gears which each have a tooth portion formed at an outer peripheral portion thereof and the tooth portions of which mesh with each other;
a housing which has a hydraulic chamber in which the pair of gears are contained in a state of meshing with each other, the hydraulic chamber having an arc-shaped inner peripheral surface with which outer surfaces of tooth tips of the pair of gears are in sliding contact;
support members which are inserted in the hydraulic chamber of the housing in a state of being respectively in contact with both end surfaces of the gears and support rotating shafts respectively provided to extend outward from both end surfaces of the gears;
the housing having an intake flow path and a discharge flow path which respectively open in one side inner surface and another side inner surface of the hydraulic chamber with the pair of gears between them; and
the pair of gears having such a theoretical tooth profile that their tooth surfaces are continuously and linearly in contact with each other in an axial direction of the rotating shafts and the tooth tips of one of the gears are brought into contact with tooth bottoms of the other of the gears, wherein
on edges of the end surfaces of the tooth portions of the gears, at least intermediate parts between the tooth tips and the tooth bottoms are chamfered and the intermediate parts have a roundness or inclination larger than those of the tooth tips and the tooth bottoms.
According to the present invention, on the edges of the end surfaces of the tooth portions of the pair of gears, at least the intermediate parts between the tooth tips and tooth bottoms are chamfered and the roundness or inclination of the intermediate parts is larger than those of the tooth tips and the tooth bottoms.
Thus, by chamfering at least the intermediate parts between the tooth tips and the tooth bottoms, the edge strength of the intermediate parts can be increased, thereby preventing the intermediate parts from being damaged due to contact stress generated when the pair of gears mesh with each other. Although a larger stress acts on the intermediate parts, particularly a power transmitting region, than on other portions, increasing the strength thereof by chamfering makes it possible to improve the durability thereof. On the other hand, because the tooth tips and the tooth bottoms are not a power transmitting region and the stress acting thereon is not so large, even if the roundness or inclination of their edge portions is made small, there is not a fear that they are damaged.
Further, in the present invention, by making the roundness or inclination of the tooth tips and the tooth bottoms smaller than that of the intermediate parts, the sealability between the end surfaces of the gears and the support members is maintained.
That is, although, if the entire edges of the tooth portions are uniformly chamfered to prevent the occurrence of damage of the edges, leakage from the high-pressure side to the low-pressure side occurs similarly to the above-described case where an edge portion is broken, such leakage can be prevented by making at least the tooth tips and the tooth bottoms have such a roundness or slop that the leakage does not occur.
As described above, the roundness or inclination of the edges of the tooth potions causes mutually contradictory phenomena that, when it is small, although the sealablity is improved, the strength is reduced and the edges are easily damaged, and that, on the other hand, when it is large, although the strength is increased and the edges are hardly damaged, the sealability is reduced and leakage easily occurs.
The inventor of the present application, as a result of eager studies, found out that it is possible to achieve both the sealabily and the strength by making the tooth tips and the tooth bottoms have a very small roundness or inclination which does not cause the leakage and making the intermediate parts have a roundness or slop which does not cause the damage.
Further, according to the present invention, it is possible to provide a lubricating effect between the end surfaces of the gears and the support members by chamfering the intermediate parts.
As described above, according to the fluid-pressure apparatus of the present invention, the original performance of being quiet and having high output efficiency can be maintained for a long time and higher reliability than before can be obtained.
Further, in the present invention, it is particularly preferable that edge portions corresponding to the power transmitting region (hereinafter, referred to as “power-transmitting-region portions”) are chamfered. As described above, since particularly large stress acts on the power-transmitting-region portions, chamfering the portions can prevent damage thereof.
It is noted that the “power-transmitting-region portion” means a theoretical curve portion which is represented by theoretical curves used in general gears, such as an involute curve and a trochoid curve, specifically a theoretical curve portion which is arranged in the vicinity of a pitch point of the gears and cannot be expressed by one perfect circle (single R). The power-transmitting-region portion is generally positioned in a range of 0.1 h to 0.9 h from the tooth bottom, where h is the tooth depth of the gears. Further, in the present invention, it is particularly preferable that the intermediate part is positioned in a range of 0.26 h to 0.81 h from the tooth bottom.
Further, in the present invention, the pair of gears may be helical gears, and in this case, the chamfering may be performed on only the intermediate parts on a side where the angle between the end surface of the gear and the tooth surface is acute.
The strength of the acute-angle edge portions is lower than that of the obtuse-angle edge portions, and, although there is no fear of damage to the obtuse-angle edge portions, risk of damage to the acute-angle edge portions is high. Therefore, by chamfering the acute-angle edge portions, risk of damage can be reduced for the entire edges. Further, by suppressing the part to be chamfered to minimum, the sealability between the edges and the support members can be maintained more appropriately.
Further, in the present invention, it is preferable that the width of chamfering performed on the intermediate parts is between 0.05 and 0.8 mm, and it is more preferable that it is between 0.1 and 0.2 mm. It is noted that the “depth of chamfering” here means, in a case where the chamfering is round, the chord length dimension of the arc portion, and means, in a case where the chamfering is a inclination, the width of the inclination.
Advantageous Effects of Invention
As described in detail above, according to the fluid-pressure apparatus of the present invention, since, on the edges of the end surfaces of the tooth portions of the gears, at least the intermediate parts between the tooth tips and the tooth bottoms are chamfered and the roundness or inclination of the intermediate parts is made larger than those of the tooth tips and the tooth bottoms, it is possible to prevent the edges from being damaged due to contact force generated when the pair of gears mesh with each other, and it is possible to prevent leakage of the operation fluid through between the gears and the support members. Thereby, the original performance of being quiet and having high output efficiency can be maintained for a long time and higher reliability than before can be obtained.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view showing a state where edge portions of an end surface of a gear is chamfered;
FIG. 2 is a schematic diagram for explaining a method of determining a width of chamfering of an edge portion of an end surface of a gear;
FIG. 3 is a table indicating results of a performance degradation experiment of an oil hydraulic device;
FIG. 4 is a sectional view of a contact portion between a pair of gears and a bush, for explaining an effect of the present invention;
FIG. 5 is a sectional view of a contact portion between a gear, a bush and a body, for explaining the effect of the present invention;
FIG. 6 is a sectional view of a contact portion between the pair of gears and the bush, for explaining the effect of the present invention;
FIG. 7 is a sectional view of a contact portion between the pair of gears and the bush, for explaining the effect of the present invention;
FIG. 8 is a sectional view showing a configuration a conventional oil hydraulic device;
FIG. 9 is a sectional view taken along A-A in FIG. 8 ;
FIG. 10 is a perspective view showing a state where buses are in contact with end surfaces of a pair of gears meshing with each other;
FIG. 11 is a plane view showing a state where helical gears mesh with each other;
FIG. 12 is a perspective view showing a state where edge portions of an end surface and a tooth surface of a gear are broken;
FIG. 13 is a sectional view of a contact portion between a pair of gears and a bush in the conventional oil hydraulic device;
FIG. 14 is a sectional view of a contact portion between a gear, a bush and a body in the conventional oil hydraulic device; and
FIG. 15 is a sectional view of a contact portion between a pair of gears and a bush, for explaining a problem in the conventional oil hydraulic device.
DETAILED DESCRIPTION
Hereinafter, in connection with a fluid-pressure apparatus according to a specific embodiment of the present invention, as an example, an oil hydraulic device using a hydraulic oil as operation fluid will be described with reference to FIGS. 1 to 7 . It is noted that the oil hydraulic device according to this embodiment has, instead of the pair of helical gears 20 ′, 23 ′ of the conventional oil hydraulic device 1 shown in FIGS. 8 to 11 , a similar pair of helical gears 20 , 23 edges of end surfaces of which are chamfered, and, other than that, the configuration thereof is the same as that of the conventional oil hydraulic device 1 . Therefore, detailed explanation of the same components as those of the conventional oil hydraulic device 1 is omitted.
In the pair of helical gears 20 , 23 of the oil hydraulic device according to the present embodiment, on the edges of the end surfaces of the gears 20 , 23 , only edge portions where the angle between the end surface and the tooth surface is acute (an acute angle portion 27 a shown in FIG. 2 , corresponding to the acute angle portion 27 a ′ shown in FIG. 10 ) are chamfered, and the width of chamfering is varied from the tooth tip to the tooth bottom and the width of chamfering of the intermediate part is larger than those of the tooth tip and the tooth bottom (see FIG. 1 ). This is specifically explained with reference to FIG. 2 . It is noted that a chamfered portion is indicated by the reference M.
FIG. 2 is a schematic diagram for explaining a method of determining the width of chamfering of an edge portion of an end surface of the gears 20 , 23 . It is noted that h in FIG. 2 indicates the tooth depth of the tooth portion. In a case where: the portion from the tooth bottom to h 1 is defined as a tooth bottom part; the portion from h 1 to h 2 is defined as an intermediate part; the portion from h 2 to the tooth tip is defined as a tooth tip part; and a predetermined maximum depth of chamfering is set, the tooth bottom part is chamfered so that the width of chamfering is gradually increased from 0 to the maximum width of chamfering starting from the tooth bottom to h 1 , the intermediate part is chamfered so that the width of chamfering of the entire part is the maximum width of chamfering, and the tooth tip part is chamfered so that the width of chamfering is gradually decreased from the maximum width of chamfering to 0 starting from h 2 to the tooth tip.
Here, it is preferable that the values of h 1 and h 2 are set so that the power-transmitting-region portion is included between h 1 and h 2 , and h 1 is from 0.1 h to 0.5 h (positioned at 10 to 50% of the tooth depth from the tooth bottom) and h 2 is from 0.5 h to 0.9 h (portioned at 50 to 90% of the tooth depth from the tooth bottom). In other words, it is preferable that the intermediate part is set within a range of 0.1 h to 0.9 h, and as a more preferable example, an example in which h 1 =0.26 h and h 2 =0.81 h can be given.
It is noted that, although, in the foregoing, the widths of chamfering of the tooth tip part and the tooth bottom part are 0, in actual machining, it is very difficult to set the width of chamfering to 0. Therefore, it is allowed to make the tooth tip part and the tooth bottom part have such a width of chamfering that an acceptable degree of leakage from the high-pressure side to the low-pressure side occurs.
Further, the width of chamfering of the intermediate part does not have to be uniform and may be gradually changed. In brief, it is important to make the intermediate part have such a width of chamfering that the intermediate part can obtain a predetermined strength. In this sense, it is preferable that the width of chamfering of the intermediate part is from 0.05 to 0.8 mm, and it is more preferable that it is from 0.1 to 0.2 mm.
In the oil hydraulic device of the present embodiment having the above-described configuration, since the width of chamfering of the intermediate parts of the acute angle portions 27 which are easily damaged when the gears 20 , 23 mesh with each other is set to be larger than those of the tooth tips and the tooth bottoms of the edges, the strength of the intermediate parts are increased and the durability thereof is improved. Therefore, when using this oil hydraulic device as an oil hydraulic pump or an oil hydraulic motor, even if contact stress concentrates at the intermediate parts due to meshing of the pair of gears, the intermediate parts are prevented from being damaged or broken, and it is possible to remarkably improve the durability thereof as compared with the conventional oil hydraulic device.
On the other hand, since the widths of chamfering of the tooth tip part and the tooth bottom part are set to 0 or such a width of chamfering that leakage from the high-pressure side to the low-pressure side is within an acceptable range, similarly to the conventional oil hydraulic device 1 , it is possible to secure high sealability between the end surfaces of the gears 20 , 23 and the end surfaces of the bushes 30 , 32 , and it is possible to secure high output efficiency.
That is, if the entire edges of the gears 20 , 23 are chamfered, as shown in FIGS. 4 and 6 , large gaps 50 , 52 are generated between the gears 20 , 23 and the bush 30 ( 32 ) at a portion where a tooth tip part and a tooth bottom part of the gears 20 , 23 mesh with each other and a portion where the intermediate parts of the gears 20 , 23 mesh with each other, respectively, and the operation fluid leaks through the gaps 50 , 52 . Further, similarly, as shown in FIG. 5 , a large gap 51 is generated between the gear 20 ( 23 ), the body 3 and the bush 30 ( 32 ), and the operation fluid leaks through the gap 51 . Therefore, in this case, while the strength of the edges can be increased, leakage of the operation fluid occurs on the entire edges and therefore there is a problem that high sealability cannot be secured.
It is noted that FIG. 4 is a sectional view of a portion where a tooth tip part and a tooth bottom part of the gears 20 , 23 mesh with each other and FIG. 6 is a sectional view of a portion where the intermediate parts of the gears 20 , 23 mesh with each other. Further, FIG. 5 is a sectional view of a portion where the gear 20 ( 23 ) is in contact with the body 3 and the bush 30 ( 32 ).
To the contrary, in the oil hydraulic device according to the present embodiment, as described above, the widths of chamfering of the tooth tip part and the tooth bottom part on which high stress does not act are set to 0 or set to such a width of chamfering that leakage from the high-pressure side to the low-pressure side is within an acceptable range. Therefore, as seen from FIGS. 13 and 14 , at the tooth tip parts and the tooth bottom parts, a gap between the gears 20 , 23 and the bush 30 ( 32 ) and a gap between the gear 20 ( 23 ), the body 3 and the bush 30 ( 32 ) are very small, and, even if the leakage occurs, it can be suppressed within an acceptable range.
Further, since predetermined chamfering is performed on only the intermediate parts of the acute angle portions 27 a which are easily broken when the gears 20 , 23 mesh with each other, as shown in FIG. 7 , although a gap 53 generated between the gears 20 , 23 and the bush 30 ( 32 ) is larger as compared with a case where chamfering is not performed thereon, it is smaller than the gap 52 shown in FIG. 6 . Therefore, the amount of leakage is reduced for that. It is noted that FIG. 7 is a sectional view of a portion where the intermediate parts mesh with each other in a case where chamfering is performed on only the intermediate parts of the acute angle portions 27 .
Thus, according to the oil hydraulic device of the present embodiment, for the above-described reasons, an effect that the durability is high and high output efficiency can be maintained for a long time as compared with the conventional oil hydraulic device 1 is achieved.
EXAMPLE
In this connection, the inventor of the present application performed a performance comparison experiment using an oil hydraulic pump corresponding to the conventional oil hydraulic device 1 using helical gears the edges of the tooth portions of which are not chamfered (Comparative Example 1), an oil hydraulic pump using helical gears the entire edges of the tooth portions of which are chamfered (Comparative Example 2) and an oil hydraulic pump using helical gears only the acute-angle edge portions of the tooth portions of which are chamfered so that the width of chamfering of the intermediate part between tooth tip part and the tooth bottom part is larger than those of the tooth tip part and the tooth bottom part (Example). The results thereof are described below. It is noted that FIG. 3 is a table which indicates the results obtained when the above-mentioned oil hydraulic pumps were driven and the discharge flow rates thereof were measured at a predetermined time interval.
As shown in FIG. 3 , the oil hydraulic pumps of the Example, the Comparative Example 1 and the Comparative Example 2 have the same theoretical discharge flow rate. In the Example, the initial discharge flow rate measured was 107.4 L/min (94% of the theoretical value), and, the discharge flow rate measured after 200 hours had elapsed was almost the same, that is, 107 L/min. On the other hand, in the Comparative Example 1, although the initial discharge flow rate measured was 109 L/min (95.4% of the theoretical value), thereafter, the discharge flow rate was reduced as time elapsed, and, after 200 hours had elapsed, the discharge flow rate was 103 L/min (90.1% of the theoretical value) and the discharge flow rate has been reduced by 2.8% as compared with the initial discharge flow rate. Further, in the Comparative Example 2, although the initial discharge flow rate was 95.5 L/min (83.6% of the theoretical value), which was low as compared with the Example and the Comparative Example 1, the discharge flow rate thereof was not reduced with elapse of time like the Example and the discharge flow rate after 200 hours had elapsed was 94.5 L/min (82.7% of the theoretical value).
As described above, in the oil hydraulic pump of the Example, the initial discharge flow rate is 94% of the theoretical value, and therefore it has a high discharge flow rate (that is, high volume efficiency) equivalent to that of the conventional oil hydraulic device 1 (the Comparative Example 1). This means that volume efficiency is not affected even when the intermediate parts are chamfered.
On the other hand, in the Comparative Example 2 in which the entire edges were chamfered, the obtained initial discharge flow rate was only 83.6% of the theoretical value. This indicates that, when the tooth tip parts and the tooth bottom parts of the edge portions are chamfered, the leakage becomes extremely large and the volume efficiency thereof is remarkably lowered.
Further, in the Example and the Comparative Example 2, the discharge flow rate was not changed so much even after the operation time has elapsed. This indicates that, since chamfering the edges of the tooth portions increases the strength of the edges and therefore the edges are hardly damaged, the seability between the end surfaces of the gears and the end surfaces of the bushes is preferably maintained even after the operation time has elapsed.
On the other hand, in the Comparative Example 1 in which the edges were not chamfered, the discharge flow rate was reduced as time elapsed, and, after 200 hours have elapsed, the discharge flow rate has been reduced by 2.8% as compared with the initial discharge flow rate. In a case where the edges are not chamfered, the edges are easily broken, and, in view of the foregoing, it is seen that the edges are broken with elapse of time, and thereby the sealability between the end surfaces of the gears and the end surfaces of the bushes is reduced and the leakage is increased.
Thus, according to the oil hydraulic pump of the Example, it is possible to obtain high volume efficiency and maintain it for a long time.
As described in detail above, in the oil hydraulic pump of the present embodiment, since only the acute-angle edge portions of the end surfaces of the tooth portions of the pair of helical gears are chamfered so that the intermediate parts thereof have a larger width of chamfering than those of the tooth tip parts and the tooth bottom parts, it is possible to increase the strength of the intermediate parts and prevent the intermediate parts from being broken. Further, such chamfering makes it possible to secure high volume efficiency equivalent to that of the conventional oil hydraulic device 1 and maintain the high volume efficiency for a long time, thereby improving the durability as compared with the conventional oil hydraulic device 1 and obtaining high reliability.
It is noted that, although, as described above, except for the fact that the edges of the end surfaces of the pair of helical gears 20 , 23 are chamfered, the oil hydraulic device according to the present embodiment has the same configuration as that of the conventional oil hydraulic device 1 shown in FIGS. 8 to 11 , a specific mode in which the present invention can be realized is not limited thereto.
For example, although, in the above embodiment, the fluid-pressure apparatus according to the present invention was embodied as an oil hydraulic pump as an example, it is not limited thereto and may be an oil hydraulic motor, for example. Further, the operation fluid is not limited to the hydraulic oil, and coolant may be used as operation fluid, for example. In this case, the fluid-pressure apparatus according to the present invention is embodied as a coolant pump.
Further, the oil hydraulic device of the above embodiment has the configuration in which a pair of helical gears are used, the configuration thereof is not limited thereto and the oil hydraulic device may have a configuration in which a pair of spur gears are used. In this case, one or both of the edges of the end surfaces of the tooth portions can be chamfered.
Further, although the oil hydraulic device of the above embodiment has the configuration in which the buses 30 , 32 are directly in contact with the gears 20 , 23 , it may have a configuration in which plate-shaped sliding members (for example, side plates) are respectively interposed between the bushes 30 , 32 and the gears 20 , 23 . Furthermore, each of the bushes 30 , 32 may be divided in two and both sides of the rotating shafts 21 , 24 may be individually supported by the four bushes.
Further, a configuration may be employed in which a key groove is formed in the tapered portion of the rotating shaft 21 and a key is inserted in the key groove, and an appropriate rotary body is coupled to the tapered portion of the rotating shaft 21 by the key groove and the key.
Further, although, in the above embodiment, the intake port 5 and the discharge port 6 are bored as through holes in the body, the intake hole 5 and the discharge hole 6 may be anything as long as they lead to the hydraulic chamber 4 . Therefore, the intake port 5 and the discharge port 6 may be formed in the body, the first flange 8 and/or the second flange 11 to form flow paths (an intake flow path and a discharge flow path) one ends of which lead to the hydraulic chamber 4 though an opening formed in the body 3 and the other ends of which lead to the outside through an opening formed in the first flange 8 and/or the second flange 11 .
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A pair of meshed gears is disposed in a hydraulic chamber of a housing. Bushes in the chamber contact both end surfaces of the gears. Edge surfaces of the gears are chamfered at intermediate parts between tooth tips and tooth bottoms, and the inclination of the intermediate parts is larger than those of the tooth tips and bottom, thereby protecting the edges from damage due to contact force as the gears mesh and preventing leakage between the gears and the support members. Accordingly, the gears may be operated quietly, at high output efficiency, and increased reliability for an extended period.
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BACKGROUND OF THE INVENTION
This invention relates to new mitomycin derivatives and processes for production thereof.
As described in the Merck Index (Ninth Edition), the mitomycins are a complex of compounds having anti-tumor, antibiotic activity. Exemplary of the known mitomycins are those having the following structure and derivatives thereof.
______________________________________ ##STR2## X 9 10 R.sub.A R.sub.B______________________________________Mitomycin A OCH.sub.3 CH.sub.3 HMitomycin B OCH.sub.3 H CH.sub.3Mitomycin C NH.sub.2 CH.sub.3 HMitomycin D NH.sub.2 H CH.sub.3Mitomycin E NH.sub.2 CH.sub.3 CH.sub.3Porfiromycin NH.sub.2 CH.sub.3 CH.sub.3______________________________________
While the known mitomycins exhibit good activity, new antibacterial compounds are always in demand. To this end, the present inventors have found new mitomycin derivatives which have a double bond between the 9 and 10 positions and which have antibacterial activity.
SUMMARY OF THE INVENTION
In accordance with the present invention, mitomycin derivatives are produced having the general formula (I): ##STR3## wherein X is an alkoxy group or an amino group, and Y is hydrogen or an alkyl group.
The invention also pertains to various semi-synthetic and fermentative processes for producing the compounds of the foregoing formula.
The compounds of the present invention have broad antibacterial activity and are, therefore, useful to clean and sterilizing laboratory glassware and surgical instruments, and may also be used in combination with soaps, detergents and wash solutions for sanitary purposes. The compound may also be useful as medicaments or intermediates in the preparation of other mitomycin derivatives having similar activity.
DESCRIPTION OF THE INVENTION
Compounds of the present invention are represented by the general formula (I): ##STR4## wherein X is an alkoxy group including a lower alkoxy group, such as methoxy, ethoxy, i-propoxy, n-butoxy, t-butoxy, and the like or is an amino group; Y is hydrogen or an alkyl group including a lower alkyl group, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl or the like.
Exemplary of these compounds are:
(1) 10-decarbamoyloxy-9-dehydro-mitomycin B (hereinafter referred to as Compound I);
(2) 9a-O-methyl-10-decarbamoyloxy-9-dehydro-mitomycin B (hereinafter referred to as Compound II);
(3) 7-amino-10-decarbamoyloxy-9-dehydro-7-demethoxy-mitomycin B (hereinafter referred to as Compound III); and
(4) 7-amino-9a-O-methyl-10-decarbamoyloxy-9-dehydro-7-demethoxy-mitomycin B (hereinafter referred to as Compound IV).
Compounds I to IV correspond to the compounds of the above general formula wherein X and Y are the following groups and atoms.
______________________________________ X Y______________________________________Compound I OCH.sub.3 HCompound II OCH.sub.3 CH.sub.3Compound III NH.sub.2 HCompound IV NH.sub.2 CH.sub.3______________________________________
Minimum inhibitory concentrations (m.c.g/ml) of these compounds against various bacteria are shown in Table 1.
TABLE 1______________________________________Test BacteriaCompound (a) (b) (c) (d)______________________________________I 0.782 0.098 >50 12.5II 6.25 0.391 >50 12.5III 3.125 0.098 25 3.125IV 50 0.196 >50 12.5V <0.025 <0.025 3.125 0.196VI 3.125 0.782 25 3.125V Mitomycin BVI 7-amino-7-demethoxy-mitomycin B(a) Staphylococcus aureus ATCC 6538P(b) Bacillus subtilis No. 10707(c) Shigella sonnei ATCC 9290(d) Klebsiella pneumoniae ATCC 10031______________________________________
The compounds of the present invention may be produced by the following methods.
(A) A mitomycin derivative wherein Y is hydrogen in the general formula (I): namely a compound represented by the general formula: ##STR5## wherein X has the same meaning as defined above, is obtained by eliminating carbamic acid from a mitomycin represented by the general formula: ##STR6## wherein X has the same meaning as defined above, in the presence of a base, and in a solvent inert to the reaction. The starting material is a known compound such as mitomycin B.
Suitable solvents for the reaction include tetrahydrofuran, dioxane, n-hexane, benzene, N,N-dimethylformamide, ethyl acetate, acetone, chloroform, and the like. Suitable bases for the reaction include sodium carbonate, sodium hydroxide, sodium hydride, triethylamine, potassium-t-butoxide, 1,5-diazabicyclo[5.4.0]undecene-5, and the like.
Typically, 1 to 30 times, preferably 1 to 10 times per mole of the base is used to the starting mitomycin. The reaction is generally carried out at -80° to 70° C., preferably at -30° to 50° C. The reaction time varies according to reaction temperature and the base used, but is usually 3 hours to 3 days.
After completion of the reaction, the desired compound is isolated and purified from the reaction solution by a conventional purification method such as that described in Examples 1 and 2.
(B) A compound wherein X in the general formula (I) is an amino group, namely a compound represented by the general formula ##STR7## wherein Y has the same meaning as defined above, is obtained by reacting a compound represented by the general formula ##STR8## wherein R 1 is an alkyl group and Y has the same meaning as defined above with ammonia in an inert solvent.
The starting compound is a compound wherein X in the general formula (I) is an alkoxy group and is obtained by methods (A), (C) or (D). Suitable inert solvents for the reaction include ethanol, methanol, water, and the like.
Typically, 1 to 10 3 times, preferably 1 to 10 2 times per mole of ammonia is used to the starting mitomycin. The reaction is generally carried out at -30° to 50° C., preferably at 0° to 30° C. and is generally completed in 1 to 48 hours.
After the completion of the reaction, the desired compound is isolated and purified from the reaction solution by a conventional purification method such as that described in Example 4.
(C) A compound wherein Y in the general formula (I) is an alkyl group, namely a compound represented by the general formula ##STR9## wherein X has the same meaning as defined above and R 2 is an alkyl group, is obtained by alkylating a compound represented by the general formula ##STR10## wherein X has the same meaning as defined above with an alkylating agent in the presence of a base and in an inert solvent.
The starting compound is a compound wherein Y is hydrogen in the general formula (I). As an alkylating agent, ethyl iodide, dimethyl sulfate, or the like may be used. Suitable bases and inert solvents are those mentioned in method (A) above.
The base and alkylating agent are typically employed in an amount of 1 to 50 times preferably 1 to 10 times per mole of the starting mitomycin. The reaction is generally carried out at -30° to 50° C., usually at room temperature and is completed in a few seconds to 24 hours. Isolation and purification of the desired compound from the reaction mixture is carried out by the same method as in method (A) above.
(D) The compounds of the invention as represented by the general formula (I) may also obtained by culturing a microorganism belonging to the genus Streptomyces which is capable of producing such compounds in a nutrient medium, accumulating one or more of the compounds in the culture liquor and recovering the same therefrom. Any microorganism may be used so long as it belongs to the genus Streptomyces and is capable of producing a compound represented by the general formula (I). Preferably, a microorganism which belongs to the species Streptomyces caespitosus and has the ability to produce one or more of the compounds is employed such as Streptomyces caespitosus ATCC 27422. The microorganisms useful in carrying out the present invention can be mutated by artificial means such as ultraviolet irradiation, X-ray irradiation and use of various mutation inducing chemicals in known manner to enhance the production of metabolic products. Accordingly the present invention contemplates use of such mutants insofar as they have the ability to produce one or more of the desired compounds.
As the nutrient medium, any medium may be used so long as it contains an assimilable carbon source, nitrogen source, inorganic materials and other nutrients required by the particular strain. As a carbon source, glucose, fructose, blackstrap molasses, and the like may be used. As a nitrogen source, ammonia, ammonium phosphate, ammonium sulfate, ammonium acetate, urea, peptone, corn steep liquor, yeast extract, meat extract, dry yeast, etc. may be used. As inorganic materials, potassium hydrogen phosphate, sodium chloride, calcium carbonate, and the like are appropriate.
Culturing is carried out with shaking or by a submerged stirring culturing method. The culturing temperature is usually at 25° to 35° C. The pH of the fermentation medium is preferably maintained at about 6 to 8 but it is usually unnecessary to control this factor. Usually after 4 to 5 days culturing substantial antibacterial activity is detected in the culture liquor at which time culturing may be discontinued.
After the completion of culturing, recovery of the desired compound from the culture liquor may be carried out by those methods usually used for purification of an antibiotic, such as is described in Examples 5 to 7.
Certain specific embodiments of the invention are illustrated by the following representative examples.
EXAMPLE 1
Preparation of 10-decarbamoyloxy-9-dehydro-mitomycin B (Compound I) ##STR11##
In this example, 100 mg of mitomycin B is dissolved in 5 ml of dioxane. To this solution, 100 mg of potassium t-butoxide is added and the mixture is stirred at room temperature for 2 days. The reaction mixture is then neutralized with an excess amount of dry ice and subjected to filtration. The filtrate is concentrated under reduced pressure and the residue is then subjected to silica gel column chromatography using a mixed solvent of acetone and chloroform (1:4) (volume ratio as is the same hereinafter) as a developer. Fractions of eluate which have a high Rf value and are blue are combined and concentrated under reduced pressure. The residue is crystallized from acetone and petroleum ether to obtain 14 mg of the desired compound (yield 17.0%) as purplish black needle-like crystals having the following physical properties.
(1) The compound exhibits molecular peak of M + =288.1086 (calculated molecular weight is 288.1110 as C 15 H 16 N 2 O 4 ) by high resolution mass spectrometry.
(2) The compound exhibits a purplish blue single spot of Rf value of 0.70 by silica gel thin layer chromatography (Art 5719 made by Merck & Co.) using a mixed solvent of acetone and chloroform (1:1) as the developer (Mitomycin B exhibits Rf value of 0.30 in the same condition).
(3) IR spectrum (KBr tablet) as is shown in FIG. 1.
(4) Chemical shift of proton by 60 MHz NMR using tetramethylsilane as internal standard and chloroform-D as a measuring solvent is shown by δ(ppm): 6.32(s, 1H), 5.53(s, 1H), 3.00-4.20(1H), 2.27(2H), 2.18(s, 3H), 3.98(d, 1H), 3.45(d, 1H), 1.75(s, 3H), 4.05(s, 3H).
EXAMPLE 2
Preparation of 7-amino-10-decarbamoyloxy-9-dehydro-7-demethoxy-mitomycin B (Compound III) ##STR12##
In this example, 1 g of 7-amino-7-demethoxy-mitomycin B and 3 g of silica gel (#7729 made by German Merck Co.) are added to 50 ml of tetrahydrofuran. To this mixture, 480 mg of sodium hydride (containing 50% of oil) is added with stirring and the mixture is stirred at room temperature for 2 days. Then, an excess amount of ethyl acetate saturated with water is added to decompose unreacted sodium hydride. An excess amount of dry ice is added to the mixture to neutralize the same. Then the mixture is subjected to filtration. The filtrate is concentrated under reduced pressure and the residue is subjected to silica gel column chromatography using a mixed solvent of acetone and chloroform (1:4) as a developer. Fractions of eluate which are eluted before unreacted starting material and are dark purplish green are combined and concentrated under reduced pressure to obtain 350 mg (yield 42.8%) of the desired compound as dark green needle-like crystals having the following physical properties.
(1) The compound exhibits molecular peak of M + =273.1118 (calculated molecular weight is 273.1113 as C 14 H 15 N 3 O 3 ) by high resolution mass spectrometry.
(2) The compound exhibits a yellowish green single spot of Rf value of 0.42 by the same silica gel thin layer chromatography as described in Example 1 (7-amino-7-demethoxy-mitomycin B exhibits Rf value of 0.10 in the same condition).
(3) IR spectrum (KBr tablet) as is shown in FIG. 2.
(4) Chemical shift of proton by 60 MHz NMR using tetramethylsilane as internal standard and a mixed solvent of chloroform-D and dimethyl sulfoxide-D 6 as a measuring solvent is shown by δ(ppm): 5.90(s, 1H), 5.32(s, 1H), 6.33(s, 1H), 2.23(2H), 2.17(s, 3H), 4.22(d, 1H), 3.43(d, 1H), 1.70(s, 3H), 6.47(s, 2H).
EXAMPLE 3
Preparation of 9a-O-methyl-10-decarbamoyloxy-9-dehydro-mitomycin B (Compound II) ##STR13##
In this example, 20 mg of 10-decarbamoyloxy-9-dehydro-mitomycin B is added to a mixed solvent of 0.3 ml dimethylformamide and 1 ml benzene. To this mixture, 20 mg of sodium hydride (containing 50% of oil) is added with stirring. Then 0.035 ml of dimethyl sulfate is added to the mixture and the mixture is stirred for 2 minutes. Ethyl acetate saturated with water is added to the mixture to decompose unreacted sodium hydride. The mixture is then filtered and 10 ml ethyl acetate is added to the filtrate. The mixture is washed 5 times each with 2 ml of water. The organic layer is then dried with anhydrous sodium sulfate and concentrated under reduced pressure. The residue is subjected to silica gel column chromatography using a mixed solvent of acetone and chloroform (1:9) whereby 8.7 mg (yield 41.5%) of the desired compound is obtained as purplish blue needle-like crystals having the following physical properties.
(1) The compound exhibits molecular peak of M + =302.1280 (calculated molecular weight is 302.1266 as C 16 H 18 N 2 O 4 ).
(2) The compound exhibits a purplish blue single spot of Rf value of 0.80 by the same silica gel thin layer chromatography as described in Example 1 (10-decarbamoyloxy-9-dehydro-mitomycin B exhibits Rf value of 0.70 in the same condition).
(3) IR spectrum (KBr tablet) as shown in FIG. 3.
(4) Chemical shift of proton by 60 MHz NMR using tetramethylsilane as internal standard and chloroform-D as a measuring solvent is shown by δ(ppm): 6.32(s, 1H), 5.50(s, 1H), 3.07(s, 3H), 2.25(2H), 2.22(s, 3H), 4.08(d, 1H), 3.41(dd, 1H), 1.85(s, 3H), 4.08(s, 3H).
EXAMPLE 4
Preparation of 7-amino-9a-O-methyl-10-decarbamoyloxy-9-dehydro-7-demethoxy-mitomycin B (Compound IV) ##STR14##
In this example, 10 mg of 9a-O-methyl-10-decarbamoyloxy-9-dehydro-mitomycin B is added to 5 ml of methanol saturated with ammonia. The mixture is stirred at room temperature for 18 hours, and then concentrated to dryness under reduced pressure. The residue is crystallized from acetone and petroleum ether to obtain 6.2 mg of the desired compound (yield 65.2%) as green needle-like crystals.
(1) The compound exhibits molecular peak of M + =287.1252 (calculated molecular weight is 287.1269 as C 15 H 17 N 3 O 3 ).
(2) The compound exhibits a deep green single spot of Rf value of 0.63 by the same silica gel thin layer chromatography as described in Example 1 (9a-O-methyl-10-decarbamoyloxy-9-dehydro-9a-dehydroxy-mitomycin B exhibits Rf value of 0.80 in the same condition).
(3) IR spectrum (KBr tablet) as is shown in FIG. 4.
(4) Chemical shift of proton by 100 MHz NMR using tetramethylsilane as internal standard and methanol-D 4 as a measuring solvent is shown by δ(ppm): 6.08(d, 1H), 5.34(d, 1H), 3.06(s, 3H), 2.43(2H), 2.21(s, 3H), 4.26(d, 1H), 3.43(dd, 1H), 1.77(s, 3H), 4.81(exchange with CD 3 OD).
EXAMPLE 5
Preparation of 7-amino-9a-O-methyl-10-decarbamoyloxy-9-dehydro-7-demethoxy-mitomycin B (Compound IV) by fermentation.
In this example, Streptomyces caespitosus ATCC 27422 is used as a seed strain. One loopful of the strain is inoculated in 50 ml of a first seed medium in a 250 ml Erlenmeyer flask. Culturing is carried out at 28° C. for 2 days. The first culture is then transferred to a 2 l-Erlenmeyer flask with baffles containing 500 ml of a second seed medium. Culturing is carried out at 28° C. for 2 days. Then 1.5 l of the second culture (3 flasks) is transferred to a 200 l-culturing tank containing 100 l of a third seed medium. Culturing is carried out at 28° C. for 2 days with aeration and stirring (revolution: 250 r.p.m., aeration: 60 l/min.).
The first, second and third seed media comprise 15 g/l glucose, 5 g/l soluble starch, 10 g/l dry yeast, 5 g/l NaCl, 3 g/l CACO 3 , pH 7.0 (before sterilization at 120° C. for 20 minutes).
Then, 100 l of the third culture is transferred to 2 Kl-fermentation tank containing 1 Kl of a fermentation medium comprising 15 g/l sucrose, 20 g/l soluble starch, 40 g/l soybean cake, 5 g/l NaCl, 200 mg/l CoCl 2 .6H 2 O, 5 ml/l normal paraffin pH 7.2 (before sterilization at 120° C. for 20 minutes).
Culturing is carried out at 28° C. for 5 days with aeration and stirring (revolution: 80 r.p.m., aeration: 400 l/min.).
After culturing, 20 Kg of sodium tetraborate (Na 2 B 4 O 7 .10H 2 O) is dissolved in the culture liquor and 100 Kg of Radiolite #600 (trade mark of a filtrate aid, made by Showa Kagaku Kogyo Co., Ltd., Japan), is added. The microbial cells are filtered off and the filtrate is passed through a column packed with 50 l of Diaion HP-20 (trade mark for an ion exchange resin, made by Mitsubishi Kasei Kogyo Co., Ltd., Japan). The resin is washed with 250 l of deionization water and elution is carried out with 250 l of 50% aqueous methanol and subsequently with 150 l of methanol. Then 200 l of the eluate containing the desired compound is concentrated under reduced pressure to about 26 l. About 8 Kg of sodium chloride is dissolved in the concentrate, and the concentrate is extracted 5 times each with 17 l of chloroform and the chloroform layers are combined and concentrated to 1 l. To the concentrated solution, anhydrous sodium sulfate is added to dehydrate the solution. The solution is then passed through a column packed with 7 l of silica gel. Elution is carried out with a mixed solvent of chloroform and methanol (100:1-5). Fractions of the eluate containing the desired compound are combined, concentrated and subjected to silica gel column chromatography using the same solvent system as above. Fractions containing the desired compound are concentrated and subjected to silica gel column chromatography using a mixed solvent of ethyl acetate and acetone (100:1); and this chromatography is then repeated. The thus obtained fractions containing the desired product are concentrated and subjected to alumina column chromatography using a mixed solvent of chloroform and acetone (98:2). The eluate is concentrated to dryness and the residue is crystallized from acetone and petroleum ether to obtain 1.9 mg of the desired compound as green needle-like crystals having the following physical properties,
(1) Melting point about 270° C.; (browning at about 220° C.).
(2) Mass spectrum: Calculated as C 15 H 17 N 3 O 3 287.1269. Found 287.1252.
(3) PMR spectrum (in CD 3 OD): 1.77(s, 3H), 2.21(s, 3H), 2.44(bs, 2H), 3.06(s, 3H), 3.42(dd, 1H), 4.26(d, 1H), 5.34(d, 1H), 6.07(d, 1H).
(4) Electronic absorption spectrum (in MeOH): 222 nm (log ε 4.02), 289(4.03), 373(4.25), 602(2.37).
(5) IR spectrum (KBr tablet): coincides with FIG. 4.
(6) Rf value by TLC (thin layer chromatography):
TABLE 2______________________________________TLC by silica gel (art 5714made by Merck & Co.) Developer Chloroform: Ethyl acetate: Chloroform: Methanol Acetone AcetoneAntibiotic (9:1) (6:4) (6:4)______________________________________Mitomycin A 0.40 0.46 0.14Mitomycin B 0.31 0.48 0.19Mitomycin C 0.21 0.24 0.05Mitomycin D 0.14 0.24 0.05Mitomycin E 0.30 0.33 0.11Porfiromycin 0.36 0.48 0.16Compound IV 0.74 0.77 0.60Compound I 0.70 0.79 0.67Compound II 0.93 0.82 0.77______________________________________
TABLE 3______________________________________TLC by alumina (art 5731,made by Merck & Co.) Developer Chloroform: Ethyl acetate: Chloroform: Methanol Acetone AcetoneAntibiotic (9:1) (6:4) (6:4)______________________________________Mitomycin A 0.56 0.21 0.08Mitomycin B 0.40 0.14 0.04Mitomycin C 0.28 0.09 0.02Mitomycin D 0.12 0.05 0.01Mitomycin E 0.46 0.21 0.07Porfiromycin 0.47 0.29 0.08Compound IV 0.75 0.76 0.67Compound I 0.72 0.73 0.58Compound II 0.83 0.84 0.84______________________________________
______________________________________(7) Elementary analysis (as C.sub.15 H.sub.17 N.sub.3 O.sub.3): H C N______________________________________Found (%) 5.95 62.73 14.34Calculated (%) 5.96 62.70 14.63______________________________________
(8) Specific rotation: Measurement was impossible as the compound is deep green.
(9) Distinction of basic, acidic or neutral property: Neutral.
(10) Solubility: Soluble in methanol, ethanol, acetone, ethyl acetate and chloroform, very slightly soluble in benzene, ethyl ether and water, insoluble in n-hexane.
From the foregoing physical properties, the compound is identified as 7-amino-9a-O-methyl-10-decarbamoyloxy-9-dehydro-7-demethoxy-mitomycin B.
EXAMPLE 6
Production of 10-decarbamoyloxy-9-dehydro-mitomycin B (Compound I) by fermentation
In this example, the same seed media (first, second and third media) and fermentation medium as described in Example 5 are used.
One loopful of Streptomyces caespitosus ATCC 27422 is inoculated in 50 ml of the seed medium in a 250 ml-Erlenmeyer flask and culturing is carried out at 28° C. for 2 days. Second and third seed culturing are carried out in the same manner as described in Example 5. Then all of the third seed culture is transferred in a 2 Kl-fermentation tank containing 1 Kl of a fermentation medium and main fermentation is carried out in the same manner as described in Example 5.
After the completion of fermentation, a concentrated extract with chloroform is obtained in a same manner as described in Example 5. The extract is dehydrated with anhydrous sodium sulfate and passed through a column packed with alumina. Elution is carried out with chloroform. Fractions containing the desired compound are combined and concentrated, and the concentrate is allowed to stand overnight in a refrigerator. A deposited precipitate is then filtered off and the filtrate is concentrated under reduced pressure. A small amount of chloroform is added to the residue and insoluble materials are filtered off. The filtrate is then subjected to silica gel column chromatography using a mixed solvent of chloroform and acetone (10:0-3). Fractions containing the desired compound are combined and concentrated. The concentrate is again subjected to the same silica gel column chromatography as above. Fractions containing the desired compound are combined and concentrated. The concentrate is crystallized from acetone to obtain 5.6 mg of purplish black needle like crystals having the following physical properties.
(1) Melting point: about 125° C.
(2) Mass spectrum: Calculated as C 15 H 16 N 2 O 4 288.1110. Found 288.1135.
(3) PMR spectrum (in CD 3 OD): 1.84(s, 3H), 2.21(s, 3H), 2.44(bs, 2H), 3.46(dd, 1H), 4.02(s, 3H), 4.03(d, 1H), 5.48(d, 1H), 6.09(d, 1H).
(4) Electronic adsorption spectrum (in MeOH): 226 nm (log ε 4.08), 291(4.03), 324 sh (3.93), 578(3.04).
(5) IR spectrum (KBr tablet): coincides with FIG. 1.
(6) Rf value by TLC is exhibited in Tables 2 and 3.
______________________________________(7) Elementary analysis (as C.sub.15 H.sub.16 N.sub.2 O.sub.4): H C N______________________________________Found (%) 5.64 62.34 9.37Calculated (%) 5.59 62.49 9.72______________________________________
(8) Specific rotation: Measurement was impossible as the compound is purplish black.
(9) Distinction of acidic, basic or neutral property: Neutral.
(10) Solubility: Soluble in methanol, ethanol, acetone, ethyl acetate and chloroform, very slightly soluble in benzene, ethyl ether and water, insoluble in n-hexane.
From the foregoing properties, the compound is identified as 10-decarbamoyloxy-9-dehydro-mitomycin B (Compound I).
EXAMPLE 7
Production of 9a-O-methyl-10-decarbamoyloxy-9-dehydro-mitomycin B (Compound II) by fermentation
In this example, the same seed media (first, second and third seed media) and fermentation medium as described in Example 5 are used. Culturing is also carried out in the same manner as described in Example 5.
After the completion of culturing, a concentrated extract with chloroform is obtained in the same manner as described in Example 5. Anhydrous sodium sulfate is then added to the extract for dehydration. The resultant extract is passed through a column packed with alumina and elution is carried out with chloroform. Fractions containing the desired compound are combined and concentrated. The concentrate is allowed to stand overnight in a refrigerator. A deposited precipitate is filtered off and the filtrate is concentrated under reduced pressure. A small amount of chloroform is then added to the residue and insoluble materials are filtered off. The filtrate is subjected to silica gel column chromatography using a mixed solvent of chloroform and acetone (4:1 to 3:2). Fractions containing the desired compound are combined and concentrated. The concentrate is again subjected to silica gel column chromatography using a mixed solvent of chloroform and acetone (49:1 to 9:1). Fractions containing the desired compound are combined and concentrated. The concentrate is then subjected to alumina column chromatography using a mixed solvent of benzene and ethyl acetate (95:5) as a developer. The filtrate is concentrated to dryness and the residue is crystallized from n-hexane to obtain 2.8 mg of purplish blue needle-like crystals having the following physical properties.
(1) Melting point: 92° to 93° C.
(2) Mass spectrum: Calculated as C 16 H 18 N 2 O 4 302.1266. Found 302.1279.
(3) PMR spectrum (in CD 3 OD): 1.85(s, 3H), 2.21(s, 3H), 2.46(bs, 2H), 3.05(s, 3H), 3.38(dd, 1H), 4.02(s, 3H), 4.07(d, 1H), 5.44(d, 1H), 6.21(d, 1H).
(4) Electronic absorption spectrum (in MeOH): 220 nm (log ε 4.15), 289(4.05), 320(4.00), 569(3.08).
(5) IR spectrum (KBr tablet): coincides with FIG. 3.
(6) Rf values in thin layer chromatography are shown in Tables 2 and 3.
______________________________________(7) Elementary analysis (as C.sub.16 H.sub.18 N.sub.2 O.sub.4): H C N______________________________________Found (%) 5.99 63.29 8.88Calculated (%) 6.00 63.56 9.27______________________________________
(8) Specific rotation: Measurement was impossible as the compound is purplish blue.
(9) Distinction of acidic, base or neutral properties: neutral.
(10) Solubility: Soluble in methanol, ethanol, acetone, ethyl acetate, chloroform, benzene, ethyl ether and n-hexane, very slightly soluble in water.
From the foregoing, the compound is identified as 9a-O-methyl-10-decarbamoyloxy-9-dehydro-mitomycin B (Compound II).
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New mitomycin derivatives having antibacterial activity are produced by semi-synthetic processes and also by a fermentative method. ##STR1##
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FIELD OF THE INVENTION
[0001] The present invention relates to phosphorus-containing compounds and preparation methods thereof, and more particularly, to a phosphorus-containing compound which can directly react to form phosphorus-containing epoxy resin or serve as a hardener for an epoxy resin composition.
BACKGROUND OF THE INVENTION
[0002] Due to good resistance to solvents, excellent mechanical strength, electrically insulating properties and size stability, epoxy resin has been widely applied to coating materials, electrically insulating materials, printed circuit laminated boards and electronic packaging materials, construction and building materials, adhesives, and navigation technology. However, epoxy resin has primary defects of poor thermal resistance and burning easily, which may set significant restriction on the uses of epoxy resin. Therefore, with development of electronic technology, it is desired to improve flame retardant properties and thermal resistance of epoxy resin in compliance with increase in the requirements for these properties.
[0003] There have been a plurality of techniques available for improving the flame retardant properties of epoxy resin, the most common one of which is to introduce a flame retardant into an epoxy resin compound or a hardener thereof. Generally, a halogen-containing flame retardant is used. Although halogens are effective for retarding flames, they would produce erosive and toxic hydrogen halide gases. According to relevant legal rules and in concern of environmental protection, the halogen-containing flame retardant is getting prohibited in use. Therefore, it is critical to develop a novel flame retardant.
[0004] It has been reported that a phosphorus-containing flame retardant has significant advantages of low toxicity, good processing properties, low usage amount, and good compatibility with resin, making the phosphorus-containing flame retardant gradually accepted in wide applications. During a burning process of the phosphorus-containing flame retardant, on the one hand, polymeric materials are urged to undergo a dehydration reaction by which hydrogen of carbohydrate reacts with oxygen of air to form water so as to reduce an ambient temperature and thereby provide a flame retardant effect. On the other hand, phosphoric acid is decomposed under a high temperature, making polymeric compounds carbonized to form a flame retardant coke layer; moreover, phosphoric acid would be further dehydrated and esterized under the high temperature to form glass-like melted polymeric phosphoric acid that covers surfaces of burning substances and serves as a protective layer for preventing oxygen from entering into non-burning internal portions of polymers and for impeding release of volatile decomposed substances, thereby inhibiting proliferation of flames and achieving the flame retardant effect.
[0005] Currently used phosphorus-containing substances can be divided into reactive phosphorus-containing compounds with function groups, and generally non-reactive phosphorus-containing compounds. The non-reactive phosphorus-containing compounds have relatively poor thermal resistance and are not suitably applied to epoxy resin compositions required to be highly thermal resistant. The reactive phosphorus-containing compounds bonded to other molecules can thus have relatively higher thermal stability and thereby become a mainstream of usage.
[0006] Among available reactive phosphorus-containing compounds, the most commonly used is a linear phosphorus-containing compound; however, due to an —O—P—O— bond on a main chain thereof, this linear phosphorus-containing compound has poorer thermal resistance than a normal halogen-containing or halogen-free epoxy resin composition. In another aspect, phosphorus-containing flame retardant resin compositions, no matter having linear phosphorus-containing compounds or non-reactive phosphorus-containing compounds, are worse in processing properties than bromine-containing epoxy resin compositions in practical applications. Therefore, it is deemed hard to enhance both the flame retardant properties and thermal resistance of the resin compositions.
[0007] In accordance with the foregoing problems, it is here to provide a novel phosphorus-containing compound and a preparation method thereof. This phosphorus-containing compound has a different side chain structure from a conventional linear phosphorus-containing compound, which not only can react to form phosphorus-containing epoxy resin by means of various addition or epoxidation reactions but also can directly act as a hardener in an epoxy resin composition. This would effectively improve flame retardant properties and thermal resistance of the resin composition, thereby particularly suitable for epoxy resin compositions required to be highly thermal resistant.
SUMMARY OF THE INVENTION
[0008] An objective of the present invention is to provide a phosphorus-containing compound represented by formula (I) with symbols thereof being defined hereinafter. This compound can be used to form flame retardant phosphorus-containing resin, and also can serve as a hardener for a flame retardant epoxy resin composition.
[0009] Another objective of the invention is to provide a method for preparing the phosphorus-containing compound, which performs an addition reaction for an organic cyclic phosphorus compound with an aryl aldehyde compound and performs a condensation reaction for an organic acid as a catalyst with an aryl compound having active hydrogen so as to form the phosphorus-containing compound according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] The present invention provides a phosphorus-containing compound represented by formula (I):
[0011] wherein R 1 is selected from the group consisting of —OH, —COOH, —NH 2 , —CHO, —SH, —SO 3 H, —CONH 2 , —NHCOOR 4 , and anhydride, and R 4 is hydrogen or alkyl; Ar 1 and Ar 2 are independently selected from:
[0012] wherein R 2 is selected from the group consisting of hydrogen, alkyl group, alkoxyl group, nitro group, halogen, and aryl group; R 3 is a chemical bond or an alkylene group; R 5 is selected from the group consisting of a chemical bond, —CR 2 R 4 —, —O—, —CO—, —S—, —SO—, and —SO 2 —; R 1 and R 4 are defined as above; a and b are independently an integer from 0 to 6, and a+b≦6; c and d are independently an integer from 0 to 4, and c+d≦4; and z is an integer from 1 to 20.
[0013] The alkyl group represented by R 2 and R 4 is a linear, branched or cyclic alkyl group, including: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, 2-pentyl, 3-pentyl, 2-methyl-1-butyl, isopentyl, s-pentyl, 3-methyl-2-butyl, neopentyl, hexyl, 4-methyl-2-pentyl, cyclopentyl, cyclohexyl, and the like. The alkylene group represented by R 3 includes: methylene, ethylene, propylene, butylene, pentylene, and hexylene, and the like. The alkoxyl group represent by R 2 includes: methoxyl, ethoxyl, propoxyl, isopropoxyl, butoxyl, isobutoxyl, s-butoxyl, t-butoxyl, pentoxyl, isopentoxyl, neopentoxyl, hexoxyl, cyclohexoxyl, and the like. The aryl group represent by R 2 includes: phenyl, methyl phenyl, dimethyl phenyl, benzyl, naphthyl, and the like.
[0014] The phosphorus-containing compound represented by formula (I) is prepared by performing an addition reaction for a reactive organic cyclic phosphorus compound having a single function group with an aryl aldehyde compound to form a phosphorus-containing compound having an alcohol group, and then performing a condensation reaction for the phosphorus-containing compound having an alcohol group with an aryl compound at least having a substituent of —OH, —COOH, —NH 2 , —CHO, —SH, —SO 3 H, —CONH 2 , —NHCOOR 4 , or anhydride in the use of an organic acid as a catalyst.
[0015] An example of the reactive organic cyclic phosphorus compound have a single function group is 9,10-dihydro-9-oxo-10-phosphorous phenanthrenyl-10-oxide represented by formula (II):
[0016] The aryl aldehyde compound for preparation of the phosphorus-containing compound according to the invention at least has a substituent selected from the group consisting of —OH, —COOH, —NH 2 , —CHO, —SH, —SO 3 H, —CONH 2 , —NHCOOR 4 , and anhydride, and includes a substituted or unsubstituted benzaldehyde compound or naphthaldehyde compound. The benzaldehyde compound may be the one represented by formula (III):
[0017] wherein R 1 , R 2 and R 3 are defined as above; m is an integer from 1 to 5; and n is an integer from 0 to 4, and m+n≦5.
[0018] Examples of the benzaldehyde compound include, but not limited to, hydroxyl benzaldehyde, hydroxyl methyl benzaldehyde, hydroxyl ethyl benzaldehyde, hydroxyl isopropyl benzaldehyde, carboxyl benzaldehyde, carboxyl methyl benzaldehyde, carboxyl ethyl benzaldehyde, carboxyl isopropyl benzaldehyde, amino benzaldehyde, amino methyl benzaldehyde, amino ethyl benzaldehyde, amino isopropyl benzaldehyde, phenyl dialdehyde, hydroxyl phenyl dialdehyde, carboxyl phenyl dialdehyde, and amino phenyl dialdehyde that are substituted or unsubstituted by alkyl, alkoxyl, nitro, halogen, or aryl; and phenyl thiophenol, hydroxyl phenyl thiophenol, carboxyl phenyl thiophenol, amino phenyl thiophenol, benzyl thiophenol, hydroxyl benzyl thiophenol, carboxyl benzyl thiophenol, amino benzyl thiophenol, phenyl sulfonic acid, hydroxyl phenyl sulfonic acid, carboxyl phenyl sulfonic acid, amino phenyl sulfonic acid, benzamide, hydroxyl benzamide, carboxyl benzamide, amino benzamide, phenyl amino methyl formate, phenyl amino ethyl fornate, phenyl amino isopropyl formate, benzyl amino methyl formate, benzyl amino ethyl formate, phenyl dimethyl anhydride, benzenediol, phenyl dicarboxylic acid, phenyl disulfonic acid, and phenyl diamide each of which has at least one aldehyde group on a benzene ring thereof; and the like.
[0019] Examples of the naphthaldehyde compound for preparation of the phosphorus-containing compound according to the invention include, but not limited to, naphthaldehyde, hydroxyl naphthaldehyde, hydroxyl methyl naphthaldehyde, hydroxyl ethyl naphthaldehyde, hydroxyl isopropyl naphthaldehyde, carboxyl naphthaldehyde, carboxyl methyl naphthaldehyde, carboxyl ethyl naphthaldehyde, carboxyl isopropyl naphthaldehyde, amino naphthaldehyde, amino methyl naphthaldehyde, amino ethyl naphthaldehyde, amino isopropyl naphthaldehyde, naphthyl dialdehyde, hydroxyl naphthyl dialdehyde, carboxyl naphthyl dialdehyde, and amino naphthyl dialdehyde that are substituted or unsubstituted by alkyl, alkoxyl, nitro, halogen, or aryl; and naphthyl thiophenol, hydroxyl naphthyl thiophenol, carboxyl naphthyl thiophenol, amino naphthyl thiophenol, naphthyl methyl thiophenol, hydroxyl naphthyl methyl thiophenol, carboxyl naphthyl methyl thiophenol, amino naphthyl methyl thiophenol, naphthyl sulfonic acid, hydroxyl naphthyl sulfonic acid, carboxyl naphthyl sulfonic acid, amino naphthyl sulfonic acid, naphthamide, hydroxyl naphthamide, carboxyl naphthamide, amino naphthamide, naphthyl amino methyl formate, naphthyl amino ethyl formate, naphthyl amino isopropyl formate, naphthyl methyl amino methyl formate, naphthyl methyl amino ethyl formate, naphthyl dimethyl anhydride, naphthyl diphenol, naphthyl dicarboxylic acid, naphthyl disulfonic acid, and naphthyl diamide each of which has at least an aldehyde group on a naphthyl ring thereof; and the like.
[0020] Besides the above benzaldehyde compounds and naphthaldehyde compounds, other aryl aldehyde compounds with each benzene ring at least having an aldehyde group are also suitable for preparing the phosphorus-containing compound according to the invention. Examples of these aryl aldehyde compounds include, but not limited to, diphenyl compounds, dephenyl alkyl compounds, dephenyl ether compounds, dephenyl methyl ketone compounds, dephenyl thioether compounds, dephenyl sulfoxide compounds, and dephenyl sulfone compounds each of which has at least an aldehyde group on a benzene ring thereof, and the like.
[0021] The aryl compound for the condensation reaction with the above phosphorus-containing compound having an alcohol group is represented by the following formula (IV) or (V):
[0022] wherein R 1 , R 2 and R 3 are defined as above; m is an integer from 1 to 5; n is an integer from 0 to 4, and m+n≦5; p is an integer from 1 to 7; and q is an integer from 0 to 6, and p+q≦7.
[0023] Besides the aryl compound represented by formula (IV) or (V), the condensation reaction can be performed for the above phosphorus-containing compound having an alcohol group with a diphenyl compound, dephenyl alkyl compound, dephenyl ether compound, dephenyl methyl ketone compound, dephenyl thioether compound, dephenyl sulfoxide compound, and dephenyl sulfone compound each of which has at least a substituent of —OH, —COOH, —NH 2 , —CHO, —SH, —SO 3 H, —CONH 2 , —NHCOOR 4 , or anhydride.
[0024] Aryl compounds subject to a condensation reaction with phosphorus-containing compounds having alcohol groups preferably have hydroxyl groups, carboxyl groups, or amine groups. Examples thereof include, but not limited to, phenol, phenyl methanol, phenyl ethanol, benzoic acid, phenyl acetic acid, phthalatic acid, hydroxyl benzoic acid, aniline, benzyl amine, amino phenol, amino phenyl sulfonic acid, amino phenol sulfonic acid, hydroxyl methyl aniline, hydroxyl ethyl aniline, amino benzoic acid, naphthol, 2,6-dihydroxy naphthalene, naphthyl formic acid, naphthyl diformic acid, naphthyl amine, naphthyl diamine, amino naphthol, amino naphthyl sulfonic acid, amino naphthyl phenol sulfonic acid, hydroxyl methyl naphthyl amine, hydroxyl ethyl naphthyl amine, and amino naphthyl formic acid.
[0025] Beside the above aryl compounds, the phosphorus-containing compound according to the invention can be prepared through the use of the following aryl compounds including: 4-hydroxyl diphenyl, 4,4′-dihydroxyl diphenyl, 4-carboxyl diphenyl, 4,4′-dicarboxyl diphenyl, 2,2-bi(4-hydroxyl phenyl)propane, 2-(3-hydroxyl phenyl)-2-(4′-hydroxyl phenyl)propane, bi(4-hydroxyl phenyl)methane, 2,2-bi(4-carboxyl phenyl)propane, 2-(3-carboxyl phenyl)-2-(4′-carboxyl phenyl)propane, bi(4-carboxyl phenyl)methane, 4-hydroxyl phenyl ether, bi(2-hydroxyl benzene)ether, bi(3-hydroxyl benzene)ether, bi(4-hydroxyl benzene)ether, 4-carboxyl phenyl ether, bi(2-carboxyl benzene)ether, bi(3-carboxyl benzene)ether, bi(4-carboxyl benzene)ether, 4-hydrozyl dibenzyl ketone, bi(2-hydroxyl benzene)methyl ketone, bi(3-hydroxyl benzene)methyl ketone, bi(4-hydroxyl benzene)methyl ketone, 4-carboxyl dibenzyl ketone, bi(2-carboxyl benzene)methyl ketone, bi(3-carboxyl benzene)methyl ketone, bi(4-carboxyl benzene)methyl ketone, 2-hydroxyl-4-methyl dibenzyl ketone, 2-hydroxyl-4-methoxydibenzyl ketone, 2,2′-dihydroxyl-4,4′-dimethyl dibenzyl ketone, 4-carboxyl-2-methyl dibenzyl ketone, 4-amino dibenzyl ketone, 4-hydroxyl diphenyl thioether, bi(2-hydroxyl benzene)thioether, bi(3-hydroxyl benzene)thioether, bi(4-hydroxyl benzene)thioether, 4-carboxyl diphenyl thioether, bi(2-carboxyl benzene)thioether, bi(3-carboxyl benzene)thioether, bi(4-carboxyl benzene)thioether, 2-hydroxyl-4-methyldiphenyl thioether, 2-hydroxyl-4-methoxydiphenyl thioether, 2,2′-duhydroxyl, 4,4′-dimethyl diphenyl thioether, 4carboxyl-2-methyl diphenyl thioether, 4-amino diphenyl thioether, bi(2-hydroyl benzene)sulfoxide, bi(3-hydroxyl benzene)sulfoxide, bi(4-hydroxyl benzene)sulfoxide, bi(2-carboxyl benzene)sulfoxide, bi(3-carboxyl benzene)sulfoxide, bi(4-carboxyl benzene)sulfoxide, bi(2,3-dihydroxyl benzene)sulfoxide, bi(5-chloro-2,3-dihydroxyl benzene)sulfoxide, bi(2,4-dihydroxyl benzene)sulfoxide, bi(2,4-dihydroxyl-6-methyl benzene)sulfoxide, bi(5-chloro-2,4-dihydroxyl benzene)sulfoxide, bi(2,5-dihydroxyl benzene)sulfoxide, bi(3,4-dihydroxyl benzene)sulfoxide, bi(3,5-dihydroxyl benzene)sulfoxide, bi(2,3,4-trihydroxyl benzene)sulfoxide, bi(2,3,4-trihydroxyl-6-methyl benzene)sulfoxide, bi(5-chloro-2,3,4-trihydroxyl benzene)sulfoxide, bi(2,4,6-trihydroxyl benzene)sulfoxide, bi(5-chloro-2,4,6-trihydroxyl benzene)sulfoxide, bi(2-hydroxyl benzene)sulfone, bi(3-hydroxyl benzene)sulfone, bi(4-hydroxyl benzene)sulfone, bi(2-carboxyl benzene)sulfone, bi(3-carboxyl benzene)sulfone, bi(4-carboxyl benzene)sulfone, bi(2,4-dihydroxyl benzene)sulfone, bi(3,4-dihydroxyl benzene)sulfone, bi(3,5-dihydroxyl benzene)sulfone, bi(3,6-dihydroxyl benzene)sulfone, and bi(3,5-dimethyl-4-hydroxyl benzene)sulfone; and the like.
[0026] The organic acid as a catalyst for preparation of the phosphorus-containing compound according to the invention may be substituted or unsubstituted carboxylic acid or sulfonic acid. Examples thereof include, but not limited to, formic acid, acetic acid, propionic acid, butyric acid, 2-methyl propionic acid, pentanoic acid, 3-methyl butyric acid, 2-methyl butyric acid, hexanoic acid, heptylic acid, octanoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, hydroxyacetic acid, lactic acid, tartaric acid, citric acid, malic acid, ethylene diamine tetraacetic acid, salicylic acid cyclohexyl carboxylic acid, 1,4-cyclohexyl dicarboxylic acid, benzoic acid, phthalatic acid, phenyl tricarboxylic acid, trifluoro methyl sulfonic acid, ethyl sulfonic acid, propyl sulfonic acid, phenyl sulfonic acid, phenyl disulfonic acid, naphthyl disulfonic acid, and p-toluene sulfonic acid.
[0027] The phosphorus-containing compound according to the invention can be prepared as follows. An addition reaction is performed for an organic cyclic phosphorus compound represented by the above formula (II) with an aryl aldehyde compound to form a phosphorus-containing compound having an alcohol group. With respect to 1 mol of the organic cyclic phosphorus compound represented by formula (II), an amount of the aryl aldehyde compound used is 0.7 to 1.3 mol, preferably 0.8 to 1.2 mol, and more preferably 0.9 to 1.1 mol. There is no particular limitation to reaction conditions for the addition reaction. A reaction temperature is preferably 80° C. to 160° C., and the reaction time is preferably longer than 0.5 hour. It should be understood that the reaction conditions may be modulated according to practical requirements. After the phosphorus-containing compound having an alcohol group is obtained, an organic acid is used as a catalyst, and a condensation reaction is performed for the obtained phosphorus-containing compound having an alcohol group with an aryl compound at least having a substituent of —OH, —COOH, —NH 2 , —CHO, —SH, —SO 3 H, —CONH 2 , —NHCOOR 4 , or anhydride, to thereby obtain the phosphorus-containing compound represented by formula (I) according to the invention. With respect to 1 mol of the phosphorus-containing compound having an alcohol group obtained from the addition reaction, an amount of the aryl compound used for the condensation reaction is greater than 0.8 mol, preferably greater than 1 mol, and more preferably more than 3.5 to 7 mol. An amount of the organic acid or catalyst is not particularly limited, but preferably 0.01 to 5 wt % of the total weight of the reactants. There is no particular limitation to reaction conditions for the condensation reaction. A reaction temperature is preferably above 90° C., and the reaction time is preferably longer than 2 hours. It should be understood that the reaction conditions may be modulated according to practical requirements.
[0028] The present invention also provides a method for preparing the phosphorus-containing compound represented by formula (I), including the steps of: (1) performing an addition reaction for an aryl aldehyde compound with an organic cyclic phosphorus compound represented by formula (II) to form a phosphorus-containing compound having an alcohol group, wherein an amount of the aryl aldehyde compound used is 0.7 to 1.3 mol with respect to 1 mol of the organic cyclic phosphorus compound represented by formula (II); and (2) performing a condensation reaction for the phosphorus-containing compound having an alcohol group obtained from the addition reaction with an aryl compound at least having a substituent of —OH, —COOH, —NH 2 , —CHO, —SH, —SO 3 H, —CONH 2 , —NHCOOR 4 , or anhydride, wherein an amount of the aryl compound used for the condensation reaction is greater than 0.8 mol with respect to 1 mol of the obtained phosphorus-containing compound having an alcohol group.
[0029] The invention can be more fully understood by reading the following Examples which should not set any restriction to the scope embraced by this invention.
EXAMPLES
Example 1
[0030] 216 g of 9,10-dihydro-9-oxo-10-phosphorous phenanthrenyl-10-oxide and 216 g of toluene are placed in a glass reactor and heated and stirred to dissolve. When the temperature reaches 110° C., 112 g of 4-hydroxybenzaldehyde is added and reacts for more than 3 hours. After the temperature cools to room temperature, the reactants are filtered and dried to obtain an organic cyclic phosphorus compound, (9,10-dihydro-9oxo-10-phosphorous phenanthrenyl-10-oxide-10-yl)-(4-hydroxyphenyl)methanol (hereinafter abbreviated as HCAB) with a melting point of 212° C.
[0031] 338 g of the organic cyclic phosphorus compound (HCAB) and 338 g of toluene are placed in a glass reactor and heated and stirred to dissolve. When the temperature reaches 110° C., 94 g of phenol and 1.6 g of p-toluene sulfonic acid are added and react for more than 3 hours. After the temperature cools to room temperature, the reactants are filtered and dried to obtain the phosphorus-containing compound according to the invention, (9,10-dihydro-9-oxo-10-phosphorous phenanthrenyl-10-oxide-10-yl)-bi(4-hydroxyphenyl)methane (hereinafter abbreviated as HPP) with a melting point of 291° C. Element composition of the phosphorus-containing compound (HPP) is analyzed below:
C % H % P % Measured value 72.7% 4.6% 7.4% Calculated value 72.46% 4.59% 7.49%
Example 2
[0032] 216 g of 9,10-dihydro-9-oxo-10-phosphorous phenanthrenyl-10-oxide and 216 g of toluene are placed in a glass reactor and heated and stirred to dissolve. When the temperature reaches 110° C., 112 g of 4-hydroxybenzaldehyde is added and reacts for more than 3 hours. After the temperature cools to room temperature, the reactants are filtered and dried to obtain an organic cyclic phosphorus compound, (9,10-dihydro-9oxo-10-phosphorous phenanthrenyl-10-oxide-10-yl)-(4-hydroxyphenyl)methanol (hereinafter abbreviated as HCAB) with a melting point of 212° C.
[0033] 338 g of the organic cyclic phosphorus compound (HCAB) and 338 g of toluene are placed in a glass reactor and heated and stirred to dissolve. When the temperature reaches 110° C., 94 g of phenol and 3.4 g of oxalic acid are added and react for more than 3 hours. After the temperature cools to room temperature, the reactants are filtered and dried to obtain the phosphorus-containing compound according to the invention, (9,10-dihydro-9-oxo-10-phosphorous phenanthrenyl-10-oxide-10-yl)-bi(4-hydroxyphenyl)methane (hereinafter abbreviated as HPP) with a melting point of 291° C. Element composition of the phosphorus-containing compound (HPP) is analyzed below:
C % H % P % Measured value 72.7% 4.6% 7.4% Calculated value 72.46% 4.59% 7.49%
Example 3
[0034] 216 g of 9,10-dihydro-9-oxo-10-phosphorous phenanthrenyl-10-oxide and 216 g of toluene are placed in a glass reactor and heated and stirred to dissolve. When the temperature reaches 110° C., 112 g of 4-hydroxybenzaldehyde is added and reacts for more than 3 hours. After the temperature cools to room temperature, the reactants are filtered and dried to obtain an organic cyclic phosphorus compound, (9,10-dihydro-9oxo-10-phosphorous phenanthrenyl-10-oxide-10-yl)-(4-hydroxyphenyl)methanol (hereinafter abbreviated as HCAB) with a melting point of 212° C. 338 g of the organic cyclic phosphorus compound (HCAB) and 338 g of toluene are placed in a glass reactor and heated and stirred to dissolve. When the temperature reaches 110° C., 108 g of o-cresol and 1.6 g of p-toluene sulfonic acid are added and react for more than 3 hours. After the temperature cools to room temperature, the reactants are filtered and dried to obtain the phosphorus-containing compound according to the invention, (9,10-dihydro-9-oxo-10-phosphorous phenanthrenyl-10oxide-10-yl)-bi(4-hydroxy-2-methylphenyl)methane (hereinafter abbreviated as HPC) with a melting point of 245° C.
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A phosphorus-containing compound represented by formula (I) and a preparation method thereof are provided. An addition reaction is performed for an organic cyclic phosphorus compound with an aryl aldehyde compound, and then a condensation reaction is performed with an aryl compound having active hydrogen in the use of an organic acid as a catalyst to obtain the proposed phosphorus-containing compound. This phosphorus-containing compound can be used as a hardener for resin, and improves flame retardant properties and thermal resistance for a flame retardant epoxy resin composition, thereby suitably applied to resin compositions used for manufacturing printed circuit boards and laminated circuit boards in electronic or electric products.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chipset, and more particularly, to a method for supporting a monitor to display with a chipset and related computer system.
2. Description of the Prior Art
Please refer to FIG. 1 , which is a functional block diagram of a computer system 40 having a K 8 CPU 42 produced by AMD according to the prior art. The computer system 40 further includes a chipset composed of a north bridge 44 and a south bridge 46 , a system memory 18 couples to the CPU 42 directly, a monitor 22 coupled to the north bridge 44 for displaying graphics data, and some peripheral devices, such as a keyboard 24 and a hard disk 26 , coupled to the south bridge 46 .
When the CPU 42 processes high speed data logic operations, the CPU 42 is operated in high operating state, such as a power saving state C 0 . However, when the CPU 42 doesn't process high speed data logic operations, the CPU 42 is operated in power saving states, such C 1 , C 2 or C 3 , to reduce power consumption.
When operating in the power saving state C 0 , the CPU 42 is at full speed and capable of receiving and executing instructions.
When operating in the power saving state C 1 , the CPU 42 stops receiving instructions to save power consumption.
When operating in the power saving state C 2 , the CPU 42 further stops outputting clocks.
When operating in the power saving state C 3 , the CPU 42 is unable to support a snoop operation.
When the CPU 42 doesn't operate at full speed, the CPU 42 is switched from the power saving state CO to the power saving state C 3 . When switching CPU Power states, the operating system sends an STPCLK signal through the south bridge 46 to the CPU 42 . After the CPU 42 is ready to be switched, the south bridge 46 sends an asserted LDTSTOP# (‘#’ means low voltage enabled) signal to the north bridge 44 and CPU 42 . Then the CPU 42 enters the power saving state C 3 , and the north bridge 44 disconnects to the CPU 42 . As a result, the snoop operation cannot be performed between the north bridge 44 and the CPU 42 .
When the south bridge 46 receives a bus master signal or an interrupt, power states of the CPU 42 has to be switched from a deeper power saving state (for example C 3 ) to a shallower power saving state (for example C 2 to C 0 ). Thus the south bridge 46 sends de-asserted LDTSTOP# signal to the north bridge 44 and CPU 42 for entering the CPU 42 into a shallower power saving state and reconnecting the north bridge 44 and the CPU 42 . Therefore, the bus master signal and the interrupt can function normally.
Since the monitor 22 has to display graphics data continuously and the data must be access form the system memory 18 through the CPU 42 . When the south bridge 46 sends the asserted LDTSTOP# signal to disconnect the north bridge 44 and the CPU 42 , whether the graphics data stored in a buffer of the north bridge 44 is sufficient is not controllable. Therefore, if the graphics data stored in the buffer is not sufficient, the CPU 42 has to be switched to operate in a shallower power saving state, and then more graphics data can be acquired from the system memory 18 . If the time it takes for the CPU 42 to be switched to operate from the power saving state C 3 to the power state C 0 is long, and the CPU 42 cannot acquire enough graphics data in time, the monitor 22 encounters a display interruption problem.
Taking the example of switching power state from a deeper power saving state to the power saving state C 0 , when the north bridge 44 determines that the graphics data stored in the buffer is not sufficient for the monitor 22 to display, the north bridge 44 sends an AGP BUSY signal to the south bridge 46 . Then, the south bridge 46 sends the de-asserted LDTSTOP# to the north bridge 44 and the CPU 42 for switching the CPU 42 to a shallower power saving state and reconnecting the north bridge 44 and the CPU 42 , and then performing graphics data access from the system memory 18 .
However the time consumption of the above mention steps, from sending signals to completing confirmation, is longer than that the time for the buffer in the north bridge 44 to output graphics data. This problem is more serious especially in a graphic integrated chipset due to the complicated inner circuit without having enough space for data storage.
SUMMARY OF THE INVENTION
The invention provides a chipset for overcoming the above-mentioned problems.
If the north bridge have insufficient graphics data in the buffer, the chipset can still access graphics data stored in the system memory without switching the power saving state of the CPU.
The chipset includes a south bridge, a north bridge coupled to the south bridge, a CPU and a monitor of a computer system. The CPU has at least a deep power saving state and at least a shallow power saving state. The computer system further includes a system memory. The north bridge has a state machine coupled to the CPU, and a graphics data buffer coupled to the state machine and the monitor, wherein when the CPU is in the deep power saving state and the state machine detects that graphics data transferred from the graphics data buffer to the monitor is insufficient, the state machine sends an NB control signal to the CPU to access inner data stored in the system memory.
A computer system includes: a system memory for storing an inner data; a CPU couples to the system memory, wherein the CPU having at least a shallow power saving state and a deep power saving state; a monitor; and a chipset couples to the CPU and the monitor. When the CPU is in the deep power saving state, if the graphics data stored in chipset is insufficient, the chipset sends an NB control signal to the CPU to access inner data stored in the system memory.
A method supports a monitor of a computer system with a chipset. The computer system has a CPU and a system memory coupled to the CPU, the CPU having at least a shallow power saving state and a deep power saving state. The method includes: sending an NB control signal to the CPU when the CPU is in the deep power saving state and graphics data transferred to the monitor is insufficient, and the CPU switching to access inner data stored in the system memory to provide the graphics data.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a functional block diagram of a computer system having a K 8 CPU produced by AMD according to the prior art.
FIG. 2 is a functional block diagram of a computer system having a K 8 CPU of the preferred embodiment according to the present invention.
FIG. 3 is a waveform diagram of inner control signals for switching a shallow power saving state into a deep power saving state of the prior art and the present invention.
FIG. 4 is a circuit diagram of a state machine of the computer system shown in FIG. 2 .
FIG. 5 is a truth table of signals shown in FIG. 4 .
DETAILED DESCRIPTION
Please refer to FIG. 2 , which is a functional block diagram of a computer system 70 having a K 8 CPU 62 produced by AMD of the preferred embodiment according to the present invention.
The computer system 70 further includes a chipset having a south bridge 76 and a north bridge 74 , a system memory 68 coupled to the CPU 62 directly, and a monitor 64 couples to the north bridge 74 for displaying graphics data. The north bridge 74 has a state machine 78 and a graphics data (GFX) buffer 80 .
Since only the north bridge 74 knows whether or not the monitor 64 has sufficient graphics data to display, the present invention provides a state machine 78 within the north bridge 74 to monitor the graphics data stored in the GFX buffer 80 . By using an NB control signal (which will be called LDTSTOP_NB# hereafter) sent from the state machine 78 to the CPU 62 , the CPU 62 can only enable an embedded memory controller without enabling the logic operation Therefore the north bridge 74 can still access the graphics data stored in the system memory 68 directly even if the CPU 62 still stays in the original power saving state.
FIG. 3 is a timing diagram of switching the power state from a shallower power saving state to a deeper power saving state of the prior art and the present invention.
When the south bridge 76 receives an asserted signal from the CPU 62 , the CPU 62 is switched from C 0 to C 3 . Then an LDTSTOP_SB# signal, similar to the asserted LDTSTOP# signal, is transmitted to the north bridge 74 , as shown in region 98 shown in FIG. 3 . After receiving the LDTSTOP_SB#, the north bridge 74 checks a data display status of the monitor 64 , and then sends an asserted LDTSTOP_NB# signal to the CPU 62 to disconnect the north bridge 74 and the CPU 62 only when data (which will be acquired by an internal GFX during 100 shown in FIG. 3 ) stored in the GFX buffer 80 is still sufficient for the monitor 64 to display. Since the north bridge 74 transfers data to the GFX buffer 80 by down counting method, the problem resulting from a system slowly switching power saving states and having insufficient data to display will not occur.
Moreover, if the CPU 62 is operated in a deeper power saving state (ex. C 3 ), if the graphics data stored in the GFX buffer 80 is not enough for the monitor 64 to display, the state machine 78 in the north bridge 74 sends a de-asserted LDTSTOP_NB# signal, which is a non-snoop signal and is shown in FIG. 3 in region 104 , to control the memory controller of the CPU 62 to switch to the function of accessing the system memory 68 without changing the LDTSTOP_SB# asserted state. Therefore, the power saving state of the CPU 62 doesn't change, and the data stored in the system memory 68 can be accessed to provide for the GFX buffer 80 during region 104 shown in FIG. 3 . Comparing to a region 96 of the LDTSTOP# signal shown in FIG. 3 which shows that the prior art cannot access the system memory 68 without generating a de-asserted LDTSTOP# and switching the CPU 62 to the shallower power saving state C 0 . Therefore the present invention is faster and saves more power.
Please refer to FIG. 4 , which is a circuit diagram of the state machine 78 .
The state machine 78 includes a first multiplexer 82 , a second multiplexer 84 , and a D-type flip-flop 86 . The first multiplexer 82 transfers either the LDTSTOP_SB# or a state signal GFX from the GFX buffer 80 to the second multiplexer 84 according to the state signal GFX.
For example, if the state of the state signal GFX is “ 0 ” (representing that the data stored in the GFX buffer 80 are enough for the monitor 64 to display), the first multiplexer 82 selects the LDTSTOP_SB# outputting to the second multiplexer 84 . On the contrary, if the data stored in the GFX buffer 80 are not sufficient (the state signal GFX is “1”), the first multiplexer 82 selects the state signal GFX (labeled as “1” in FIG. 4 ) outputting to the second multiplexer 84 for enabling the LDTSTOP_NB(t)# signal, which is outputted from the D-type flip-flop 86 , to be “1” as shown in FIG. 3 as region 100 . When the data stored in the GFX buffer 80 is sufficient, the state of the state signal GFX is “0”, and the first multiplexer 82 outputs the LDTSTOP_SB# signal for enabling the LDTSTOP_NB(t)# signal to be “0”, as shown in FIG. 3 as region 102 .
The second multiplexer 84 is controlled by a down counter (not shown in FIG. 3 , the down counter can be integrated into the state machine 78 ) of the north bridge 74 . When the down counter is not yet counting to zero, an assert/de-assert signal is used to control an input end, which has an output equals to “0”, for outputting an NB−1 control signal. The NB−1 control signal is generated according to feedback of LDTSTOP_NB(t)# from an output end Q of the D-type flip-flop 86 and is inputted to the input end D of the D-type flip-flop 86 via the second multiplexer 84 . Thus, if the down counter is not yet counting to zero, state of LDTSTOP_NB(t)# will keep at the state of the previous LDTSTOP_NB(t)# (called an LDTSTOP NB(t−1)# hereafter), thus the switching is performed after a predetermined period of time.
As shown in FIG. 3 , the interval between 102 and 104 is not less than a predetermined period (for example one microsecond). During the predetermined period, the north bridge 74 will not change LDTSTOP_NB#, which is transferred to the CPU 62 . On the contrary, when the down counter is counting to zero, the second multiplexer 84 using an assert/de-assert signal to control the input end, which has the output equals to “1”, for outputting LDTSTOP_SB# from an output end O 1 of the first multiplexer 82 or the state signal GFX of the GFX buffer 80 to the input end D of the D-type flip-flop 86 .
The operation of the state machine 78 for generating the LDTSTOP_NB(t) is described as follows.
Please refer to FIG. 5 , which is a truth table of the state signal GFX, the assert/de-assert signal, LDTSTOP_SB#, LDTSTOP_NB(t−1)# and LDTSTOP_NB(t)#. When the down counter is not yet counting to zero (the assert/de-assert is “0”), the duration of the LDTSTOP_NB(t)# is less than one microsecond (or less than a programmable shortest period). The computer system 70 does not allow LDTSTOP_NB(t)#, from the north bridge 74 to the CPU 62 , to switch, so the state of LDTSTOP_NB(t)# is keeps to the state of LDTSTOP_NB(t−1)# (as L 1 -L 4 and L 9 -L 12 in the table show).
When the down counter is counting to zero (the assert/de-assert shown in FIG. 5 is “1”), if the state signal GFX is equal to “0” (the first multiplexer 82 shown in FIG. 4 transfers LDTSTOP_SB# to the second multiplexer 84 ), the north bridge 74 generates succeeding LDTSTOP_NB(t)# according to LDTSTOP_SB#, as L 5 -L 8 in the table shows, without taking into consideration the state of LDTSTOP_NB(t−1).
When the down counter is counting to zero, and the state of state signal GFX is equal to “1” (the first multiplexer 82 outputs the state signal GFX, which state is equal to “1”, to the second multiplexer 84 ), the following generating LDTSTOP_NB(t) of the north bridge 74 is generated to ensure the north bridge 74 still can accessing the system memory 68 . So that, the internal GFX can access data ready to be displayed on the monitor 64 from the system memory 68 through the CPU 62 and the north bridge 74 . In FIG. 5 , this is shown as LDTSTOP_NB(t) values equal to “1” in L 12 -L 16 .
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
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A circuit, designed for supporting a computer system having a CPU, a monitor, and a system memory electrically connected to the CPU, includes a south bridge, and a north bridge electrically connected to the south bridge, the CPU, and the monitor. The north bridge includes a state machine and a graphics data buffer. When detecting that graphics data transferred by the graphics data buffer to the monitor is insufficient, the state machine sends a north bridge signal to the CPU to access inner data of the system memory.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to carrying devices and, more particularly, carts for carrying heavy loads.
2. Related Art
The construction of carts is well-known in the art. Specifically, cart constructions which utilize a rigid, immovable body mounted on wheels is typical of the art. For example, the Gander Mountain catalog, Fall 1994, which is hereby incorporated by reference in its entirety, discloses a Warren and Sweat Horse cart model with a single carrying deck and a rigid, immobile body.
However, a need arose in the art to provide carts which could be safely used and use a minimum of storage space. Accordingly, various types of carts were devised in which the rigid, immobile body was divided into several independent sections. The independent sections were removably connected to minimize storage space. For example, the Gander Mountain Fall 1994 catalog, which is hereby incorporated by reference in its entirety, discloses a Warren and Sweat Mule Big Game Carrier Cart and a Warren and Sweat Pony Cart, both of which utilize a single carrying deck and a rigid body. However, both of these carts are collapsible in the sense that they are comprised of independent sections which are removably connected to one another. In other words, the independent sections are separated to reduce storage space.
However, the fact that the independent cart sections of the prior art are completely removable is inconvenient because a relatively high degree of care and physical coordination is required to ensure that the sections are attached. Thus, assembling the cart sections is a multiple step procedure even for those carts which only have a single deck, and thus there is a need in the art to provide a cart whose body may be assembled in a single procedure.
While the carts of the prior art are constructed from removable sections, the prior art has constructed the sections such that the cart may be placed in the bed of a pickup truck or the rear-most section of a sport utility vehicle. However, none of the carts in the prior art have been designed to fit behind the driver's seat of a standard cab (non-extended cab) version of a full-sized or even small-sized pickup trucks. Accordingly, there is a need in the art to provide a cart having an upper and a lower deck whose body may be assembled in a single procedure and whose body can collapse to fit behind the driver's seat of a standard cab version of any size pickup truck.
SUMMARY OF THE INVENTION
It is in view of the above problems that the present invention was developed. The invention is a cart assembly having an upper and a lower deck whose body may be assembled in a single procedure using only one hand and whose body including the wheels can collapse to fit behind the driver's seat of a standard cab version of any size pickup truck. Specifically, a plurality of spacing members rotatably connected between the upper deck and lower deck rotate to alternately collapse and expand the cart. The cart is held in a fixed position by a brace member disposed diagonally between the upper deck and lower deck in the expanded position of the cart, and which is disposed in parallel to the upper deck and lower deck when the cart assumes its collapsed position. The brace member fixes the relative positions of the upper deck and the lower deck as the brace member has a length (and thus radius of curvature) unequal to the length (and thus radius of curvature) of the spacing member.
In its collapsed state, the cart may assume the dimensions of 421/2×7×271/2 inches, including the provision of a hitch for towing and a t-bar for manual pushing.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings:
FIG. 1 illustrates an exploded view of the cart of the present invention;
FIG. 2 illustrates the cart of the present invention in kit form;
FIG. 3 illustrates a cross-sectional view of the lower portion of the cart of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the accompanying drawings in which like reference numbers indicate like elements, FIG. 1 illustrates an exploded view of the cart, shown generally at 10, of the present invention. Cart 10 comprises upper deck shown generally at 12, lower deck shown generally at 14, first, second, third, and fourth upright members 16-22, respectively, spacing upright member 24, wheels 26-28, hitch shown generally at 30, and T-bar shown generally at 32.
First, second, third, and fourth upright members 16-22, respectively, are made from 3/4 inch square tube which may be 81/2 inches long with a square or straight cut and have 1/4 inch holes drilled through at each end approximately 5/16 of an inch from each of the ends. Preferably, where square tube is used, steel square tube is preferred, although other square tube materials may be used such as aluminum or fiberglass. Spacing upright member (or brace) 24 is made from 1 inch square tube and may be 121/2 inches long having 1/4 inch holes drilled through each end approximately 5/16 of an inch from each of the ends. Although spacing upright member 24 may be of variable size, it cannot be the same length as first, second, third, and fourth upright members 16-22. Preferably, spacing upright member 24 is longer than any of upright members 16-22 to ensure that the relative rotation radii of the respective members are not the same or similar.
Upper deck 12 comprises a four "panel" grid which is rigid and immobile. Upper deck 12 further comprises five inverted U-shaped connectors 36-44 adapted to receive a pin 46-54. The upper deck 12 is 42 inches long and 18 inches wide in overall dimensions. The "panel" nearest the front, shown generally at 56, and nearest the rear, shown generally at 58, of cart 10 may be 81/4 inches wide between the panel separating numbers. The last two remaining interior "panels" may be 11 inches wide. Upper deck 12 is constructed from 3/4 inch square steel tube. In constructing upper deck 12, the 42 inch square tube lengths are cut with 45° angles at the ends. Similarly, the 18 inch width square tube lengths are cut with 45° angles at the ends. The three upper deck interior members 60-64 may be each 161/2 inches long with straight or square cuts at each end. The square tube members comprising the upper deck are joined in a rigid immobile relationship by welding.
U-shaped connectors 36-44 have a square U-shape and are constructed from 1/16 inch plate steel, with a 1 inch outer dimension on each side of the U-shape. A 1/2 inch hole is drilled near the end of each of the legs of each of the U-shaped connectors 36-44 namely, each hole is centered 7/16 of an inch from the end of each leg. The holes in each U-shaped connector 36-44 function to receive first, second, third, and fourth pins 46-52. First, second, third, fourth, and fifth pins 46-54 may take various forms such as bolts (with nuts), cotter pins, tapered pins, grooved pins, straight pins, spring pins, spiral pins, roll pins, slip pins, or the like.
Accordingly, upper deck 12 is pivotally and releasably connected to first, second, third, and fourth upright members 16-22, respectively, and spacing upright member 24 via first, second, third, fourth, and fifth U-shaped connectors 36-44, respectively, and first, second, third, fourth, and fifth pins 46-54, respectively, simultaneously disposed through both of the holes in U-shaped connectors, as well as the holes in each of the upright members 16-24.
Similarly, lower deck 14 comprises a four "panel" grid and may assume overall dimensions of 27 inches by 24 inches. The width of the two interior "panel" members of lower deck 14 is substantially congruent with the width of upper deck 12. In addition, the length of the two interior "panel" members of lower deck 14 is substantially congruent with the length of the two interior "panel" members of upper deck 12. Exterior "panel" members of lower deck 14 extend 5 inches from interior "panel" members. Accordingly, lower deck 14 is wider than upper deck 12 for stability. Lower deck 14 may be assembled using 3/4 inch square tube, two 27 inch lengths, each having a 45° cut on each end, two 24 inch lengths, each having a 45° on each end, one 161/2 inch length with straight or square cuts on each end for separating the two interior "panel" members of lower deck 14, two 221/2 lengths with straight or square cuts on each end. The two 27 inch lengths form front member 80 and rear member 82. The two 24 inch lengths form side members 84 and 86. The two 221/2 inch members form interior side members 88 and 90.
Along the same axis as middle member 92 are first, second, third, and fourth wheel mounts 94-100. The wheel mounts 94-100, respectively, are made from 1/8 inch thick plate steel of 2 inches by 2 inches in which a portion is cut out to receive wheels 26 and 28. The shape of the cutout may take various forms. For example, the cutout may be straight and rounded only at the end as shown in FIG. 1. Alternatively, the cutout may assume an "L" path for receiving wheels 26 and 28 equipped with a quick-release fastening mechanism. First, second, third, and fourth wheel mounts 94-100, respectively, are welded 1 each to side members 84 and 86, and interior side members 88 and 90, in parallel. Thus, first, second, third, and fourth wheel mounts 94-100 may easily receive wheels 26 and 28 without regard for the wheel fastener (i.e., quick release or nut and threaded axle) utilized.
Also disposed on lower deck 14 are sixth, seventh, eighth, ninth, and tenth U-shaped connectors 104-112, respectively. As in the upper deck, the U-shaped connectors 104-112 are provided with holes for receiving sixth, seventh, eighth, ninth, and tenth pins. Accordingly, first, second, third, and fourth upright members 16-22 and spacing upright member 24 are pivotally and releasably connected to lower deck 14 via sixth, seventh, eighth, ninth, and tenth pins 114-122 disposed through the holes in U-shaped connectors 114-112 and the holes in upright members 16-24. Accordingly, as shown in FIG. 2, when fifth pin 54 is released from spacing upright member (or brace) 24, spacing upright member 24 rotates downwardly toward lower deck 14. Concurrently, upper deck 12 rotates forwardly and downwardly until it comes into longitudinal contact with first, second, third, and fourth upright members 16-22, and spacing upright member 24. After strapping each wheel with first and second straps 66 and 68, the entire cart achieves a collapsed dimension less than or equal to 421/2 inches by 271/2 inches by 7 inches. These dimensions permit the collapsed cart to be conveniently placed behind the driver's seat of a non-extended cab pickup truck, either full-sized or small-sized pickup truck. Therefore, the present invention avoids the necessity of using cargo space in the rear of a truck for storing the cart.
As shown in FIG. 1, a first steel mesh portion 126 and second mesh portion 128 may be disposed in lower deck 14 as a front portion and rear portion, respectively.
Tongue brace 132 is connected to lower deck 14 and helps support first and second steel mesh portions 126 and 128. Tongue brace 132 is connected to lower deck 14 by welding in various locations. Tongue brace 32 has a front end 134 and a rear end 136 and may be made from 11/4 inch square tube, 32 inches long square cut at both ends, and provided with a 3/8 inch hole 138 centered 21/2 inches from front end 134.
Tongue (or hitch) member 144 has a front end 146 and a rear end 148, and is constructed from 1 inch square tube 32 inches long. At front end 146 of tongue member 144, tongue element 150 is fixed by welding to tongue member 144. Tongue element 150 may be formed from 1/4 inch thick steel plate bent into U-shaped with each leg of the U having 3/4 hole drilled therethrough centered approximately 1 inch from the ends. Tongue member 144 may have a 1/4 inch rear hole 152 drilled approximately 101/2 inches from rear end 148 and a 1/4 inch front hole 154 drilled approximately 241/2 inches from rear end 148. Tongue member 144 is disposed inside tongue brace 132 as tongue member 144 is made from 1 inch square tube and tongue brace 132 is made from 11/4 inch square tube.
T-bar 32 comprises T-bar member 158 welded to T-handle 160. T-bar member 158 has a front end 162 and a rear end 164, and may be constructed from 3/4 inch square tube 38 inches long. A 3/8 inch hole 166 is drilled through T-bar member 158 at front end 162 approximately 71/2 inches from the end. T-handle 160 may be made from 3/4 inch square tube 261/4 inches long and welded at its midpoint to rear end 164 of T-bar member 158. For ease of use, T-handle 160 may be covered with a cellular cushion 168 such as foam. In its storage position, front end 162 of T-bar member 158 is inserted into rear end 148 of tongue member 144, as T-bar member 158 is of 3/4 inch square tube and tongue member 144 is of 1 inch square tube. Hole 166 of T-bar member 158, hole 154 of tongue member 144, and hole 138 of tongue brace 132 may be aligned for passage of eleventh pin 172 therethrough. Accordingly, tongue member 144 and T-bar 32 remain fixed relative to cart 10 while in its collapsed state shown in FIG. 2.
The concentric nature of tongue brace 132 encompassing tongue member 144 which itself encompasses T-bar member 158 is illustrated in FIG. 3. In use, hitch 30 may be extended longitudinally forwardly, by sliding hitch 30 within tongue brace 132 such that rear hole 152 is fixed via eleventh pin 172 in alignment with hole 138 of tongue brace 132. In this manner, hitch 30 may be attached to a towing vehicle (not shown) for towing cart 10.
In certain situations, towing is not practical or available. In these situations, T-bar 32 is used to physically push or pull the cart. However, the location of T-bar 32 in use is different from the location of T-bar 32 in storage. As may be recalled from above, in its storage position, front end 162 of T-bar member 158 is inserted into rear end 148 of tongue member 144. To prepare T-bar 32 for use, T-bar 32 is completely withdrawn by pulling it free from rear end 148 of tongue member 144. Then, front end 162 of T-bar member 158 is inserted into spacing upright member (or brace) 24. Because spacing upright member 24 is made from 1 inch square tube and T-bar member 158 of T-bar 32 is made from 3/4 inch square tube, T-bar 32 slides easily into spacing upright (brace) member 24. When hole 166 of T-bar member 158 of T-bar 32 is aligned with the hole in spacing upright (brace) member 24, fifth pin 54 is inserted through both holes and fixes T-bar 32 in place relative to cart 10. The upward angle assumed by spacing upright (brace) member 24 is therefore also assumed by T-bar 32 and permits the height of T-handle 160 to assume a comfortable position, without the necessity of stooping or reaching by a user.
In use, to render cart 10 operable from its collapsed state, a user will grasp upper deck 12 and simply pull upper deck 12 upwardly and away from lower deck 14. As upper deck 12 moves upwardly, first, second, third, and fourth upright members 16-22 pivot clockwise about sixth, seventh, eighth, and ninth U-shaped connectors 104-110 which are attached to lower deck 14, and pivot counterclockwise about first, second, third, and fourth U-shaped connectors 36-44 which are attached to upper deck 12. Upon having first, second, third, and fourth upright members 16-22 reach a vertical position, the user releases upper deck 12 and then grasps and rotates spacing upright member (brace) 24 about tenth U-shaped connector 112 until the exposed hole in spacing upright member 24 is aligned with the hole in fifth U-shaped connector 44. Then, the user releases spacing upright member 24 and inserts fifth pin 54 through both the hole in spacing upright member 24 and the hole in fifth U-shaped connector 44. Because spacing upright member 24 is longer than upright members 16-22, the radius of curvature of spacing upright member 24 is longer than that of upright members 16-22. Accordingly, upper deck 12 is prevented from rotating in any direction when fifth pin 54 fixes the free end of spacing upright member 24 to upper deck 12, as the incompatible radius of curvature of the spacing upright member 24 as compared to the other upright members 16-22 make it impossible for simultaneous rotation of all members 16-24. Thus, cart 10 may assume the dimensions of 421/2×7×271/2 inches when said upper deck has rotated towards the lower deck 14 to assume the smallest possible dimension.
It should be noted that when T-bar 32 is in use, the assembly procedure is somewhat modified. Specifically, The user releases spacing upright (brace) member 24, inserts T-bar 32 into spacing upright (brace) member 24 until the respective holes are aligned, additionally aligns the hole in fifth U-shaped connector 44, and finally inserts fifth pin 54 through three holes simultaneously, namely, the hole in spacing upright (brace) member 24, the hole 166 in T-bar member 158 of T-bar 32, and the hole in fifth U-shaped connector 44.
It should also be noted that if first, second, third, fourth, sixth, seventh, eighth, ninth, and tenth pins 46-52 and 114-122 respectively are of the nut and bolt type and are relatively tight, the upper deck 12 and the spacing upright member 24 will not move when released by the user. Accordingly, it should be pointed out that the body of cart 10 may be erected with only one hand.
Therefore, by way of example, the cart 10 of the present invention is ideally suited for activities such as deer hunting because of the ease of storage and assembly. In addition, hitch 30 allows cart 10 to be loaded with hunting equipment and towed by an all terrain vehicle. As with some hunting areas, all terrain vehicles are barred past certain points, and thus cart 10 may be unhitched from the all terrain vehicle and pushed to the deer stand. Moreover, if the hunter is successful, cart 10 may be employed to haul a deer out of the woods. For similar reasons, cart 10 of the present invention is useful in other hunting venues such as duck hunting.
In another use, cart 10 may be equipped with a stretcher-like attachment placed on top of upper deck 12 and used to transport patients to and from an ambulance or other emergency medical vehicle.
In view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained.
The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.
As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. For example, the lengths of the various segments of the body of cart 10 may be freely varied, as such lengths were provided for example only and not in a limiting sense. In addition, the cutouts of wheel mounts 92-100 were described as having certain geometries which could also be varied. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.
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The invention is a cart assembly having an upper and a lower deck whose body may be assembled in a single procedure using only one hand and whose body including the wheels can collapse to fit behind the driver's seat of a standard cab version of any size pickup truck. Specifically, a plurality of spacing members rotatably connected between the upper deck and lower deck rotate to alternately collapse and expand the cart. The cart is held in a fixed position by a brace member disposed diagonally between the upper deck and lower deck in the expanded position of the cart, and which is disposed in parallel to the upper deck and lower deck when the cart assumes its collapsed position. The brace member fixes the relative positions of the upper deck and the lower deck as the brace member has a length (and thus radius of curvature) unequal to the length (and thus radius of curvature) of the spacing member.
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RELATED APPLICATION
This application is a continuation-in-part of application Ser. No. 07/280,125, filed Dec. 5, 1988, now U.S. Pat. No. 4,949,423, issued Aug. 21, 1990.
FIELD OF THE INVENTION
This invention relates to automatic car wash equipment and, in particular, to a system for drying rinse water from a vehicle from forced air. More particularly, the invention relates to sensing the proximity of a vehicle and for adjusting the position of a forced air nozzle.
BACKGROUND OF THE INVENTION
It is known to strip rinse water from a vehicle in a car wash. See, for example, U.S. Pat. Nos. 2,448,834 and 4,161,801. In these two patents, the nozzle through which the forced air is delivered is in contact with the vehicle surface. While this method takes advantage of the fact that the air velocity and pressure are greatest in the immediate vicinity of the nozzle, the method is subject to high maintenance costs due to wear and tear on the nozzle.
In U.S. Pat. Nos. 4,587,688 and 4,622,714, the nozzle is maintained close to, but not in contact with, the vehicle surface. In U.S. Pat. No. 4,587,688, a sonar-type of proximity detector generates signals which are sent to a control system which adjusts the position of the nozzle and maintains it in relatively close proximity to the vehicle surface. A sonar-type of proximity detector system of this type is, however, limited to angles of incidence up to about 15°, beyond which the reflected signal is not detected.
SUMMARY OF THE INVENTION
A proximity detection system which, in one preferred form, employs an ultrasonic imaging transmitter/receiver (sensor), which is fixedly mounted to the support frame of the car wash equipment. This transceiver is angled to detect the contours of an oncoming vehicle, while at the same time avoiding detection of a blower-arm assembly. The transceiver of this preferred embodiment can also be adjusted to reduce the sensitivity of its signal receiving components.
The position of the blower-arm assembly is adjusted in accordance with the imaging of the oncoming vehicle to maintain an optimum distance from the surface of the vehicle without contacting the surface of the vehicle. Adjustment and positioning of the blower-arm is accomplished by comparing the output signal from the sensor to an output signal from a linear potentiometer attached to the drive piston of the blower-arm assembly. The output signal of the linear potentiometer is directly related to the position of the nozzle end of the blower arm assembly with respect to the vehicle.
An additional, fail-safe, mechanism in the form of wheel switches may also be mounted to the blower head of the blower-arm assembly to ensure that the blower head will rise should any inadvertent contact with the vehicle surface occur. An antenna detector can also be mounted to the blower arm assembly to avoid contact with an antenna that escapes detection by the sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of the blower-arm assembly, mounting frame and sonar transceiver embodying the present invention.
FIG. 2 is a diagrammatic illustration of automatic car wash equipment embodying the present invention.
FIG. 3 is an expanded view of the sonar transceiver and mounting apparatus of the present invention.
FIG. 4 is a logical block diagram of the operation of the automatic car wash apparatus embodying the present invention.
FIG. 5 is a schematic block diagram of the inputs and control box of the present invention.
FIG. 6 is an exploded view of the wheel switch.
FIG. 7 is a partial side view of the wheel switch.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is shown control system 10 for maintaining a blower nozzle of a blower arm assembly in close proximity to the surface of a vehicle. There is also provided a mechanism to override the imaging-based control of the blower's movement, should contact be made between the blower and the vehicle.
Control system 10 includes a blower arm assembly system 12 attached to a support frame 24 in a manner which allows blower head 14 and its attached blower nozzle 54 to move toward and away from an oncoming vehicle. In the present embodiment, blower head 14 and blower nozzle 54 are a one-piece weldment and blower arm assembly system 12 is mounted overhead of an oncoming vehicle. It is possible to mount a system such as blower arm assembly system 12 sideways, so that nozzle 54 would force air against the sides of an oncoming vehicle.
Blower system 12 includes blower head -4, with its attached blower nozzle 54, linkage arms 16 and 17 for positioning blower head 14 via a linkage 19 attached to a piston arm 21. Piston arm 21 extends from piston cylinder 20 and may be activated by either compressed air or hydraulic fluid or a combination thereof (i.e. air over oil). As piston 21 extends, member 19 mounted for pivotal movement about pivot 19a and connected to blower-head 14 through arm 17, moves blower-head 14 upward. Arm 17 is connected to blower-head 14 for pivotal movement about pivot 17b. Arm 17 is fixed to member 19. A second arm 16 is connected to blower-head 14 for pivotal movement about pivot 16b with the opposite end of arm 16 mounted for pivotal movement about pivot 16a.
The distance between pivots 16a and 17a is greater than the distance between pivots 16b and 17b. The length of arm 16 is equal to the linear distance between pivot 17b and pivot 19a. This relationship of the pivots results in the orientation of the blower-head 16 changing as the blower-head moves between its upper-most and lower-most positions. As an example, the arrangement shown in FIG. 2 can vary the nozzle orientation from between 15° to 20° from the vertical from the blower-head in the lower-most position and 5° to 71/2° from the vertical with the nozzle in its upper-most position. In this way the nozzle orientation is adjusted for different top portions of the vehicle being dried. When the nozzle is over the hood, it is lower than when it is over the roof. It should be noted that the above configuration may be used with dimensions that include a true parallelogram.
Attached to the outside of piston 20 is linear potentiometer 22. One side of linear potentiometer 22 includes attachment rod 23 affixed to piston arm 21. The other side of potentiometer 22 is fixed to the cylinder of cylinder 20. As piston arm 21 extends linearly outward from piston 20, a signal is output which varies in accordance with the position of piston arm 21. This signal is directly proportional to the extension of piston arm 21 from piston 20, and corresponds to the position of nozzle 54. This output signal from linear potentiometer 22 provides information to be compared with the output signal from sensor 30.
There is also shown a sensor 30 attached to support frame 24 at area 26. (Sensor 30 and the mounting of sensor 30 to support frame 24 is shown in detail in FIG. 3).
Sensor 30 outputs an ultrasonic signal which reflects off of an oncoming vehicle. This reflected signal bounces back and is received by the receiving part of sensor 30. Sensor 30 sends the received signal to sensor control 29 (FIG. 5). Sensor control 29 outputs a second signal (i.e. a voltage signal) which relates to the distance of the oncoming vehicle to sensor 30. This output signal from sensor 30 is then compared to the output signal from linear potentiometer 22, and a resultant control signal is then applied to solenoid control 78. Solenoid control 78 then signals solenoid 74 to pressurize or depressurize piston cylinder 20 to properly position nozzle 54 in close proximity to the surface of oncoming vehicle 5.
Wheel switches 44a and 44b (wheel switches 44a and b are shown in greater detail in FIGS. 6 and 7) are mounted on the front and rear portions of blower head 14 to serve as a fail-safe mechanism. Wheel switches 44 are attached to blower head 14 by mounting arms 46. Wheel switches 44 serve as fail-safe mechanisms so that if a portion of an automobile escaped detection by sensor 30, or if sensor 30 was not functioning properly, contact with the oncoming vehicle by blower nozzle 54 can be avoided.
Wheel switches 44a and 44b are positioned so that imminent contact with nozzle 54 would first result in contact with either wheel switch 44a or 44b, depending on whether the contact point is in front of or behind nozzle 54 (relative to the direction of travel of car 5). When this contact occurs, an override signal is transmitted to solenoid 74 and solenoid control 78, causing piston arm 21 to further extend from piston 20, thus raising blower head 14 to a position where contact (with car 5) is no longer made. In the present embodiment, nozzle 54 can move approximately 90 inches above the floor upon a signal from the wheel switches 44, antenna switch 60 or sensor control 29. In comparison, if nozzle 54 is fully descended, in the present embodiment, it is approximately 42 inches above the floor.
Wheel switches 44a and 44b operate to override or bypass the signal from sensor 30 through a relay control system in controller 75 of FIG. 5. Thus, the wheel switches control relays which are either ON or OFF. When OFF, the signal from sensor 30 is controlling. When ON, the signal from sensor 30 is bypassed and a signal to solenoid 74 and solenoid control 78 causes pressurization of piston cylinder 20 and the actuation of piston arm 21, which raises blower head 14 and its attached blower nozzle 54.
There is shown in FIG. 2 a diagrammatic illustration of blower assembly 12 mounted on frame 24 with a vehicle 5 approaching blower assembly 12. Nozzle 54 of blower assembly 12 is positioned to trace the contours of the upper surface of vehicle 5, such as the hood, windshield, roof, rear window and trunk.
An additional feature, which may be present, in control system 10 is an antenna detection component. This antenna detection component is shown in FIG. 2 as nylon cord 60 and spring switches 61 and 62. An alternate antenna detector 80 (see FIG. 8) having a plastic flap 55 with a conductive contact material 57 may also be used. A conductive tape could serve this purpose. Nylon cord 60 is attached in the front (portion facing the approaching vehicle) of blower nozzle 54. Nylon cord 60 is attached to nozzle 54 by spring switches 61 and 62. The antenna detectors of the present invention are positioned on the side of blower nozzle 54 which corresponds to the typical placement of antennas on automobiles. Those skilled in the art will understand that the antenna detectors can be placed at any point on nozzle 54, or across the active length of nozzle 54.
When spring switches 61 or 62 are engaged by either a compression or extension, contact is made with a switch element (not shown) which, in turn, switches a relay in Elast Controller 75 to an "ON" state (similar to the operation of relays for wheel switches 44a and 44b), causing blower nozzle 54 to be raised away from the antenna which triggered the signal. This signal activates a relay control system in Elast Controller 75 and overrides the ultrasonic imaging currently taking place.
When an override signal from either the wheel switches or the antenna detector occurs and blower head 14 and nozzle 54 are raised to a position where contact (with oncoming car 5) is no longer made, a delay timer (located in solenoid control 78, FIG. 5) is also activated for reengaging the ultrasonic imaging and repositioning blower nozzle 54. In the present embodiment, a delay timer can be set for between 0 and 5 seconds with a one-second delay currently being used. The delay mechanism allows for the blower to be repositioned through ultrasonic imaging by sensor 30 after the blower head and nozzle are raised for a sufficient time to let the surface causing the contact pass under the blower head. When the delay cycle is over, the relays (located in solenoid control 78, FIG. 5) for either the wheel switches or the antenna detector are reset.
There is shown in FIG. 3 sensor mount 26, which contains the mounting means and the ultrasonic imaging sensor 30, Migatronics Model #RPS-200-72-500 in the present embodiment). Sensor 30 is an ultrasonic imaging transducer containing components for the transmission of an ultrasonic signal and also the reception of a signal reflected off of an object within its imaging window. The sensor of the present embodiment receives signals which fall within an imaging window of 36° (shown as angle B in FIG. 3).
Scaling of the sensor (reducing the sensitivity) can adjust the imaging window to avoid detection of blower nozzle 54 working in the sensing window, while still detecting the car. For the sensor of the present embodiment, avoidance of blower nozzle 54 occurs when the imaging window is reduced from 36° to approximately 20°. This 20° imaging window effectively avoids detection of the blower assembly 12 when sensor 30 is angled at 15° (angle A, FIG. 3) because the angle of incidence from sensor 30 to nozzle 54 allows most of the signal to miss the receiver (of sensor 30). The remaining signal from nozzle 54 to sensor 30 is of insufficient amplitude to be validated by sensor 30. Unvalidated signals are suppressed and do not affect the output signal of sensor 30.
Two factors have been found to substantially affect the placement and adjustment of sensor 30 for the proper imaging of the oncoming vehicle. The first factor involves avoidance of detection of blower assembly 12. The second factor involves complete imaging of the oncoming vehicle including its angled windshield.
For the present embodiment, it has been found that a combination of angling the sensor to face the oncoming vehicle and reducing the imaging window of sensor 30 addresses both factors and provides for the proper imaging of the oncoming vehicle.
In a horizontal position, sensor 30 may be positioned parallel to the horizontal (i.e. angle A is 0°). In this position, it has been found that reducing the imaging window of sensor 30 to approximately 20° effectively avoids detection of the blower assembly 12, as shown in FIG. 1. The imaging window of sensor 30 is reduced by applying a protective film or sheet in the path of the line of sight between sensor 30 and nozzle 54. Film 31 reduces the sensitivity of sensor 30 (acting as a waveguide), substantially eliminating signals from the blower assembly. The sensitivity of sensor 30 can also be reduced or controlled by other means, such as a potentiometer. As is well known in the art, a potentiometer could control the receiving or transmitting components of sensor 30 and thus reduce its sensitivity. In the present embodiment, the protective film 31 has been found to be both easy to use and highly effective.
Still considering Angle A at 0° and reducing the imaging window of sensor 30, however, introduces the second factor--effective imaging of the slanted automobile windshield 5a, FIG. 2. The reduced angle of the imaging window directs the signal at an angle towards the windshield of an oncoming vehicle in such a manner that it is reflected away from sensor 30. By reflecting the signal away from sensor 30, sensor 30 does not detect the windshield. By failing to detect the windshield, sensor 30 cannot output a signal to control the blower assembly, preventing proper control of the blower assembly.
In order to effectively image the windshield, sensor 30 is angled so that the ultrasonic signal sent towards the windshield will bounce back towards sensor 30. In the present embodiment, sensor 30 is angled so that angle A is approximately 15°. Angling sensor 30 at approximately 15° yields effective and complete imaging of the oncoming automobile while at the same time avoiding detection of the blower arm assembly. Effective imaging (to sense both windshield and the hood) by sensor 30 can be accomplished when sensor 30 is angled at approximately one half of the inside angle (the angle made up of the interior windshield and the horizontal) of the automobile windshield. Angling sensor 30 at 15° is a practical compromise to compensate for different angles encountered on the hood, windshield, top and rear deck.
Sensor 30 is mounted to support frame 24 by mounting brackets 38 and 32. Mounting bracket 38 can be welded to support frame 24, and mounting bracket 32 is attached by various mounting means. In FIG. 3, nuts and bolts 40 are shown to attach mounting bracket 32 to support frame 24. Sensor 30 is attached to mounting bracket 32 by bolt 33, washer 34 and nut 35. The output and power lines for sensor 30 are contained within conduit 36. Conduit 36 leads the output line of sensor 30 to the control box of the present invention.
There is shown in FIG. 4 a block diagram of the operation of the present invention. A vehicle enters the car wash blower region as shown in block 64. The vehicle is imaged by the imaging mechanism of sensor 30, as shown in block 66. The sensor output from sensor 30 is compared with the output of linear potentiometer 22, as shown in block 68. After this comparison of signals is made, the blower assembly is raised or lowered to position blower nozzle 54 in close proximity to the surface of the oncoming vehicle. Blocks 72 and 74 show the override function of the present invention. Decision block 72 determines whether the wheel switch is ON, as indicated by the state of a relay in Elast controller 75 of FIG. 5. This relay is normally OFF until an override signal is sent from the wheel switches or an antenna detector. Should this override signal be sent, the relay is switched to the ON position and overrides the imaging signals of the vehicle. This causes the blower arm to rise to a position where contact (with car 5) is no longer made, as shown in block 74. The blower will remain in the non-contact position as long as the timing delay is set. The delay is set for one second in the present embodiment.
Decision block 72 determines whether the antenna detector is ON. The relay works similar to that of the wheel switch in that it is OFF until a signal from the antenna detector trips the relay to the ON position. At this point, the ultrasonic imaging signal is overridden, and the blower arm would raise, as shown in block 74.
There is shown in FIG. 5 a schematic block diagram for the control and operation of the present invention. Ultrasonic sensor 30 outputs a signal to sensor control 29 which outputs a signal to comparator 31. Comparator 31 compares the signal from sensor control 29 and the signal from potentiometer 22. Potentiometer 22 outputs a signal relative to the extension of piston 21. Comparator 31 then outputs a signal to solenoid control 78 which controls solenoid 74. Solenoid 74 in turn, controls blower head 14 and blower nozzle 54 through cylinder 26.
Solenoid 74 outputs a signal to activate cylinder 20 which in turn moves piston arm 21 (not shown) to position blower 14 and by implication blower nozzle 54. The extension of piston 21 corresponds to the position of the blower-nozzle 54 relative to the vehicle.
Solenoid control 78 can receive an over-ride signal from Elast (Extremely Low Amperage Switch Terminator, Cratar Model #106) controller 75. Elast controller 75 contains a relay activated by wheel switches 44a and 44b and antenna switch 60. Additional relay circuitry and finer circuitry is contained in solenoid control 78, as is understood by those skilled in the art. Activation of Elast controller from either wheel switch 44a and 44b or antenna switch 60 generates and over-ride signal, which is set to solenoid control 78 and over-rides the signal from Comparator 31. The effect of the over-ride signal is to raise blower nozzle 54 away from on-coming vehicle 5. The raised nozzle is on a timed basis. The timer is located in solenoid control 78 and when the timing cycle is complete, blower nozzle 54 is once again positioned according to the comparison of the output signal from ultrasonic sensor 30 and the output from potentiometer 22.
There is shown in FIG. 6 an expanded view of wheel switch 44 (shown in FIG. 1 as 44a and 44b). Wheel switch 44 is comprised of wheel 42 mounted to support mounts 46. Wheel 42 can be made of any number of substances such as rubber or plastic or compounds thereof. Wheel 42 is attached to support mounts 46 by rod 47, non-conducting bushing 45 and non-conducting shim 49. Rod 47 may be made of a conducting substance such as aluminum while bushing 45 should be made of a non-conducting material such as nylon. Wheel switch 44 is activated when a portion of an oncoming vehicle makes contact with wheel 42. Wheel 42 pushes nut 48 (or pipe 48a) into contact with spring contact 50. Spring contact 50 is mounted to support means 46 by non-conducting spring mount 52 and screw 51. A wire connected to spring contact 50 at screw 51 transfers the electrical contact signal to the control means in order to raise blower nozzle 54 away from oncoming vehicle 5. The signal is generated by the contact between nut 48 (or pipe 48a) and spring contact 50 by grounding spring contact with support frame 46.
There is shown in FIG. 7, support means 46, containing non-conducting spring support 52, spring contact 50, screws 51, keeper 90 and wire 91.
Keeper 90 is made of stainless steel in the present embodiment, but other conductive materials could be used. Keeper 90 prevents spring contact 50 from deforming, as well as providing contact to wire 91. Wire 91, in turn, is connected to Elast controller 75 (FIG. 5). Spring contact 50 is also made of stainless steel in the present embodiment.
In a further embodiment of the invention it will be understood that sensor 30 may be mechanically coupled to blower-head 14 as described in Ser. No. 07/280,125, filed Dec. 5, 1988 and assigned to the same assignee as this application. Thus, in this further embodiment the distance between pivots 16a and 17a is greater than the distance between pivots 17b and 17b.
There is shown in FIG. 8 a more detailed view of flap antenna detector 80. Antenna detector 80 is an alternate antenna detector design. Antenna detector 80 has conductive contact strip 57 attached to flap 55. Flap 55 is secured to nozzle 54 by bolt 84 and rivnut 86. Sponge strip 82 "resets" flap 55 after deflection into nozzle 54 by the antenna of oncoming vehicle 5. Contact between contact strip 57 and nozzle 54 send a signal along a wire (not shown) to Elast controller 75 (FIG. 5).
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There is provided automatic car wash equipment for positioning a forced air dryer including a blower towards vehicles being washed. The blower produces high velocity air and contains a nozzle for directing the high velocity air towards the vehicles. The blower and a positioning motor are mounted to a support frame, under which an on-coming vehicle passes. The blower is positioned according to the output signal from an ultrasonic imaging sensor mounted to the support frame. The relative position of the blower is measured by a linear potentiometer mounted to the piston which positions the blower. Additional detection devices are provided for over-riding the ultrasonic signal should contact be eminent between the blower and various parts of an on-coming vehicle.
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RELATED APPLICATIONS
This application is a continuation of Ser. No. 07/440,423 filed Jan. 30, 1990, now abandoned; which is a continuation of Ser. No. 06/782,016 filed Sep. 30, 1985, now abandoned; which is a Continuation-in-Part of Ser. No. 06/262,542 filed May, 11, 1981, now U.S. Pat. No. 4,677,345; which is a Division of Ser. No. 06/178,107 filed Aug. 14, 1980.
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to ballasts for gas discharge lamps, particularly of a kind wherein the light output can be controllably maintained at any desired level.
2. Prior Art and General Background
It is well known that significant improvements in overall cost-effectivity can result from appropriately controlling the level of light output from lighting fixtures used for general lighting of offices and the like.
Fluorescent lamp ballasting systems adapted to permit control of light output level on a systems basis presently do exist--as for instance in accordance with U.S. Pat. No. 4,207,498 to Spira et al. However, there are significant complexities associated with practical applications of such light level control systems; and, in spite of the very significant improvements potentially available in cost-effectivity, such light control systems have not gained wide acceptance.
Much of the value available from a light control system may be attained by control of each individual lighting fixture. That way, for instance, light output from each fixture could be kept constant irrespective of any variations in the magnitude of the power line voltage and/or regardless of changes in luminous efficacy of the fluorescent lamp(s) used in the fixture.
SUMMARY OF THE INVENTION
OBJECTS OF THE INVENTION
One object of the present invention is that of providing an improved method of controlling the light output level of a gas discharge lamp.
A second object is that of providing a means whereby the light output level of a lighting fixture may be effectively and automatically controlled.
A third object is that of providing a cost-effective way of controllably regulating the output of an inverter-type ballast in such manner as to maintain a substantially constant light output irrespective of any variations in the magnitude of the power line voltage and/or regardless of any changes in the luminous efficacy of the gas discharge lamp.
These as well as other objects, features and advantages of the present invention will become apparent from the following description and claims.
BRIEF DESCRIPTION
In its preferred embodiment, the present invention constitutes a power-line-operated inverter-type ballast that powers one or more fluorescent lamps in a lighting fixture. The ballast comprises self-oscillating inverter wherein the frequency of oscillation can be influenced by receipt of a control signal at a pair of control terminals connected in circuit with the inverter's positive feedback circuit. The ballast also comprises optical sensor means so positioned and constituted as to sense the light level within the lighting fixture and to provide a control signal commensurate with that light level. This control signal is then applied to the control terminals in such manner as to regulate the inverter frequency as a function of the light level, thereby correspondingly to regulate the magnitude of the current fed to the fluorescent lamps. By providing a threshold means in combination with high gain in the control loop, the fixture light level may be accurately maintained at any desired value substantially regardless of any changes in magnitude of power line voltage and/or in lamp efficacies.
The inverter's positive feedback is attained by way of saturable current transformer means, and control of inverter frequency is attained by providing more or less heat to the saturable magnetic material of the current transformer means, thereby correspondingly to decrease or increase the saturation limits of this magnetic material; which, in turn, correspondingly increases or decreases the frequency of inverter oscillation.
The inverter provides its high frequency output to an L-C series-combination and the fluorescent lamp is connected in parallel circuit with the capacitor of this L-C combination.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 diagrammatically illustrates a power-line-operated self-oscillating inverter-type ballast with saturable transformer means in its positive feedback path and with electrical input means for affecting control of the inversion frequency.
FIG. 2 illustrates the effect of temperature on the saturation characteristics of the magnetic material used in the saturable transformer means.
FIG. 3 illustrates the preferred embodiment of the present invention, showing the inverter-type ballast of FIG. 1 combined with optical sensor means and control feedback means operable to keep constant the light output from a fluorescent lamp.
FIG. 4 shows the ballast of FIG. 3 as it is used in an ordinary fluorescent lighting fixture.
DESCRIPTION OF THE PREFERRED EMBODIMENT
DESCRIPTION OF THE DRAWINGS
In FIG. 1, a source S of 120 Volt/60 Hz voltage is applied to a full-wave bridge rectifier BR, the unidirectional voltage output of which is applied directly between a B+ bus and a B- bus, with the positive voltage being connected to the B+ bus.
Between the B+ bus and the B- bus are connected a series-combination of two transistors Q1 and Q2 as well as a series-combination of two energy-storing capacitors C1 and C2.
The secondary winding CTls of positive feedback current transformer CT1 is connected directly between the base and the emitter of transistor Q1; and the secondary winding CT2s of positive feedback current transformer CT2 is connected directly between the base and the emitter of transistor Q2.
The collector of transistor Q1 is connected directly with the B+ bus; the emitter of transistor Q2 is connected directly with the B- bus; and the emitter of transistor Q1 is connected directly with the collector of transistor Q2, thereby forming junction QJ.
One terminal of capacitor C1 is connected directly with the B+ bus, while the other terminal of capacitor C1 is connected with a junction CJ. One terminal of capacitor C2 is connected directly with the B- bus, while the other terminal of capacitor C2 is connected directly with junction CJ.
An inductor L and a capacitor C are connected in series with one another and with the primary windings CT1p and CT2p of transformers CT1 and CT2.
The series-connected primary windings CT1p and CT2p are connected directly between junction QJ and a point X. Inductor L is connected with one of its terminals to point X and with the other of its terminals to one of the terminals of capacitor C. The other terminal of capacitor C is connected directly with junction CJ.
A fluorescent lamp FL is connected, by way of lamp sockets S1 and S2, in parallel circuit across capacitor C.
Respectively, the two current transformers CT1 and CT2 are thermally connected with heating resistors R1 and R2; which two resistors are parallel-connected across control input terminals CIT.
Values and designations of the various parts of the circuit of FIG. 1 are listed as follows:
Output of Source S: 120 Volt/60 Hz;
Bridge rectifier BR: a bridge of four 1N4004's;
Capacitors C1 & C2: 100 uF/100 Volt Electrolytics;
Transistors Q1 & Q2: Motorola MJE13002's;
Capacitor C: 15 nF/1000 Volt(High-Q);
Inductor L: 130 turns of three twisted strands of #30 wire on a 3019P-L00-3C8 Ferroxcube Ferrite Pot Core with a 120 mil air gap;
Transformers CT1 & CT2: Wound on Ferroxcube Toroids 213T050 of 3E2A Ferrite Material with three turns of #26 wire for the primary windings and ten turns of #30 wire for the secondary windings;
Fluorescent Lamp FL: Sylvania Octron F032/31K;
Resistors R1 & R2: 0.2 kOhm/1 Watt Wirewound's.
The frequency of inverter oscillation associated with the component values identified above--with no power supplied to resistors R1 and R2--is approximately 33 kHz.
FIG. 2 shows the relationship between temperature and saturation flux density of the Ferroxcube 3E2A ferrite material used in feedback current transformers CT1 and CT2.
FIG. 3 shows the inverter-type ballast circuit of FIG. 1 arranged such as to provide for automatic control of light output from the fluorescent lamp.
A transformer T is connected with its primary winding across capacitor C; its secondary winding is connected with the AC input terminals of a full-wave rectifier FWR. The positive and negative terminals of the DC output of this rectifier are respectively marked T+ and T-.
A transistor Qa is connected with its collector to the T+ terminal by way of the CIT terminals; and it is connected with its emitter to the T- terminal.
A light sensor LS is connected between the T+ terminal and the cathode of a first Zener diode Z1. The anode of Zener diode Z1 is connected with the base of transistor Qa. An adjustable resistor Ra is connected between the cathode of the Zener diode and the T- terminal.
A second Zener diode Z2 is connected with its cathode to the collector of transistor Qa; and a warning means WM is connected between the anode of Z2 and the T- terminal.
FIG. 4 schematically illustrates the use of a ballast B, as made in accordance with the preferred embodiment of FIG. 2, in a lighting fixture LF, which is shown in quasi-cross-section.
The light sensor LS, which is shown as being placed just above the fluorescent lamp FL, is plug-in connected with the ballast B by way of a light-weight connect cord CC. The adjustable resistor Ra is indicated as being accessible from the side of the ballast; and warning means WM is indicated as being mounted on the side of the lighting fixture and plugged into the ballast in manner similar to that of the light sensor.
DESCRIPTION OF OPERATION
The operation of the circuit of FIG. 1 may be explained as follows.
In FIG. 1, the source S represents an ordinary electric utility power line, the voltage from which is applied directly to the bridge rectifier identified as BR. This bridge rectifier is of conventional construction and provides for the rectified line voltage to be applied to the inverter circuit by way of the B+ bus and the B- bus.
The two energy-storing capacitors C1 and C2 are connected directly across the output of the bridge rectifier BR and serve too filter the rectified line voltage, thereby providing for the voltage between the B+ bus and the B- bus to be substantially constant. Junction CJ between the two capacitors serves to provide a power supply center tap.
The inverter circuit of FIG. 1, which represents a so-called half-bridge inverter, operates in a manner that is analogous with circuits previously described in published literature, as for instance in U.S. Pat. No. 4,184,128 to Nilssen entitled High Efficiency Push-Pull Inverters.
The inverter circuit is shown without any means for initiating inverter oscillation. However, once B+ power is applied, oscillation can be initiated simply by momentarily connecting a 50 nF capacitor between the B+ bus and the base of transistor Q2.
Or, as is used in many other inverter circuits, an automatic triggering arrangement consisting of a resistor, capacitor, and a Diac may be used.
At a temperature of 25 Degrees Centigrade, the output of the half-bridge inverter is a substantially squarewave 33 kHz AC voltage. This squarewave voltage is provided between point X and junction CJ. Across this squarewave voltage output is connected a resonant or near-resonant L-C series circuit--with the fluorescent lamp being connected in parallel with the tank-capacitor thereof.
The resonant or near-resonant action of the L-C series circuit provides for appropriate lamp starting and operating voltages, as well as for proper lamp current limiting; which is to say that it provides for appropriate lamp ballasting.
(Resonant or near-resonant ballasting has been described in previous publications, as for instance in U.S. Pat. No. 3,710,177 entitled Fluorescent Lamp Circuit Driven initially at Lower Voltage and Higher Frequency.)
The inverter frequency may be controlled by controlling the temperature of the magnetic cores of the feedback current transformers, as can best be understood by recognizing that--in the inverter circuit of FIG. 1--the ON-time of a given transistor is a direct function of the saturation flux density of the magnetic core in the saturable feedback transformer associated with that, transistor. Thus, other things being equal and in view of the relationship illustrated by FIG. 2, the inversion frequency is a substantially proportional function of the temperature of the ferrite cores used in CT1 and CT2.
However, it should also be understood that the transistor ON-time is a substantially inverse proportional function of the magnitude of the voltage presented to the secondary windings of the saturable feedback current transformers by the base-emitter junctions of the two transistors. That is, other things being equal, the inversion frequency is substantially proportional function of the magnitude of this junction voltage; which is to say, since the magnitude of this junction voltage decreases in approximate proportion to temperature, that the inversion frequency decreases with increasing temperature on the transistors.
When combining the two effects outlined above, and by matching the effects on the inversion frequency due to the temperature effects of ferrite material with those of the counter-working temperature effects of the transistors' base-emitter junction, it is possible substantially to cancel any change in inversion frequency that otherwise might result from temperature changes occurring in a normally operating inverter circuit.
However, aside from any normally occurring changes in the inversion frequency, it is possible in a cost-effective and practical manner to cause substantial additional changes in the inversion frequency. Such changes can controllably be accomplished by way of providing a controllable flow of additional heat to the ferrite cores of the saturable feedback transformers; which is exactly what is accomplished by the two resistors identified as R1 and R2; which two resistors are coupled to the ferrite cores in close thermal relationship.
A given flow of power to the two resistors causes a corresponding proportional temperature rise of the ferrite material. Thus, the inversion frequency will increase from its base value in approximate proportion to the power input to the resistors.
In the circuit of FIG. 1, the purpose of frequency control is that of effecting control of the power output, which is accomplished by way placing a frequency dependent or reactive element in circuit with the load. That way, as the frequency is varied, the flow of power to the load is varied in some corresponding manner.
For extra effective control, this reactive element can be a tuned circuit--as indeed is used in the arrangement of FIG. 1--in which case the degree of power flow control for a given degree of frequency control is enhanced by the frequency selective characteristics of the tuned circuit.
In the particular case of FIG. 1, with no power being provided to resistors R1 and R2, the power supplied to the fluorescent lamp load is approximately 30 Watt. With a power flow of about 1 Watt provided to resistors R1 and R2, the power supplied to the fluorescent lamp load is only about 4 Watt.
Thus, by controlling the amount of power being provided to control input terminals CIT, the light output of fluorescent Lamp FL may be controlled over a wide range.
However, it should be realized that by controlling the light output of fluorescent lamp FL by way of controlling the temperature of the ferrite material in the feedback current transformers, as herein described, the response time can not be instantaneous.
While such delayed response may be annoying in conventional light dimming applications, it is of little significance in several important applications.
In particular, with reference to FIG. 3, the relatively long response time does not constitute a significant detriment in connection with controlling the light output against such effects as: i) changes in the magnitude of the voltage applied to the inverter from source S, ii) variations in the efficacy of the fluorescent lamp, whether these variations be due to lamp manufacturing differences or lamp aging, iii) variations in the ambient temperature to which the fluorescent lamp is subjected, and iv) variations in the ambient temperature to which the ballast itself is subjected.
More particularly, the ballast circuit of FIG. 3 illustrates how the circuit of FIG. 1 is used to provide for automatic control of the light output of the fluorescent lamp.
The light output level is sensed by light sensor LS, which is of such nature that its effective resistance decreases as the light flux received by it increases. Consequently, the voltage developing across adjustable resistor Ra increases with decreasing light output. Depending upon the chosen setting of Ra, with increasing light output, there comes a point at which the magnitude of the voltage across Ra gets to be so high as to cause current to flow through Zener diode Z2 and into the base of transistor Qa; which then causes power to be provided to resistors R1 and R2. In turn, the power provided to these resistors will cause heating of the ferrite cores of feedback transformers CT1 and CT2, thereby reducing the amount of power supplied by the ballast to the fluorescent lamp.
As an overall result, the light output from the lamp will be kept substantially constant at a level determined principally by the threshold provided in the control feedback loop; which threshold is determined by the sum of the voltage drop across the Z1 Zener diode and that of the base-emitter junction of transistor Qa.
Thus, with adequate gain in the total feedback loop (which principally consists of elements LS, Ra, Z1, Qa, R1, R2, CT1, CT2 and the Thermal Coupling Means), the light output will be maintained at a substantially constant level characterized by the point at which the magnitude of the voltage across Ra reaches this threshold--that is, reaches a threshold high enough to cause current to flow through the Z1 Zener diode and into the base of transistor Qa.
If the light output level were to fall below this threshold, current would cease flowing through transistor Qa, and power flow to the ferrite cores will be choked off; thereby causing the cores to cool down and, as a result, more power to be provided to the lamp.
Whenever the light output is inadequate to cause the magnitude of the voltage across Ra to reach the threshold, base current ceases to be provided to Qa, and the magnitude of the voltage across Qa will reach its maximum level; which maximum level is principally determined by the magnitude of the voltage between the T- and the T+ terminals. In turn, this magnitude is determined by the voltage developing across the fluorescent lamp in combination with the voltage transformation ratio of transformer T.
The parameters of Zener diode Z2 and warning means WM are so chosen that power will be provided to warning means WM whenever the magnitude of the voltage across Qa reaches its maximum level; which means that a warning will be provided whenever the light output from fluorescent lamp FL fails to reach a certain level.
Although different types of devices may be used as warning means WM, it is herein anticipated that the warning means be simple liquid crystal device parallel-loaded with a leakage resistor.
Or, the warning means could simply be a light-emitting diode, in which case the Zener diode may be substituted with a resistor.
FIG. 4 shows a fluorescent lighting fixture wherein a ballast B, made in accordance with the ballast circuit of FIG. 3, is positioned and connected with the fixture's fluorescent lamp(s) in a substantially ordinary manner.
A calibrated means for adjusting the magnitude of resistor Ra is accessible from the outside of the ballast.
Light sensor LS and warning means WM are each provided as an entity at one end of a light weight electrical cord; which cord has a plug at its other end. This plug is adapted to be plugged into a receptacle in the ballast itself, thereby to be properly connected in circuit with the feedback loop.
The complete feedback loop is electrically isolated from the power line and the main ballast circuit; which therefore readily permits both LS and WM, as well as their receptacles, cords and plugs, to be made and installed in accordance with the specifications for Class-2 or Class-3 electrical circuits, as defined by the National Electrical Code.
Like LS and WM, Ra could just as well have been provided as a plug-in entity at the end of a light weight cord; and, like Ra, both LS and WM could just as well have been provided as rigidly integral parts of the ballast itself.
Light sensor LS is positioned in such a way as to be exposed to the ambient light within the fixture; warning means WM is placed in a location whereby it is readily visible from some suitable place external of the fixture; and ballast B is placed in such manner as to provide for Ra to be reasonably accessible for adjustment.
The main purpose of warning means WM is that of providing a visually discernible signal to the effect that it is time to change the lamp(s) in the fixture.
The main purpose of adjustable resistor Ra is that of permitting adjustment of the level of light to be provided from the fixture.
Additional Comments
a) When a fluorescent lamp is initially provided with power, its light output will be substantially lower than it will be once the lamp has warmed up to proper operating temperature. Under most normal circumstances, the ballast of FIG. 3 provides compensation for this effect, in that the lamp will automatically be provided with substantially more power as long as the light output is not up to the desired level--even if the reason relates to the fact that the lamp has not reached proper operating temperature yet.
During this initial warm-up period, the warning means may indicate a need to replace the lamp. However, the warning signal should be disregarded, or at least interpreted with special care, during this initial lamp warm-up period.
b) In order for the feedback control loop to be considered as a Class-2 electrical circuit, it is convenient to limit the magnitude of the DC voltage provided between terminals T- and T+ to about 30 Volt. Also, the magnitude of the maximum current available therefrom should be limited to 8 Amp.
c) To provide for even more accuracy in the control feedback function, the magnitude of the voltage provided between the Band the B+ terminals could be regulated with a separate Zener diode. However, for most applications, the degree of voltage regulation provided by the fluorescent lamp should be adequate.
d) It is believed that the present invention and its several attendant advantages and features will be understood from the preceeding description. However, without departing from the spirit of the invention, changes may be made in its form and in the construction and interrelationships of its component parts, the form herein presented merely representing the presently preferred embodiment.
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A power-line-operated inverter-type ballast powers one or more fluorescent lamps in a lighting fixture. The ballast comprises self-oscillating inverter means wherein the frequency of oscillation can be influenced by receipt of a control signal at a pair of control terminals connected in circuit with the inverter's positive feedback circuit. The ballast also comprises optical sensor means so positioned and constituted as to sense the light level within the lighting fixture and to provide a control signal commensurate with that light level. This control signal is then applied to the control terminals in such manner as to regulate the inverter frequency as a function of the light level, thereby correspondingly to regulate the magnitude of the current fed to the fluorescent lamps. By providing a threshold means in combination with high gain in the control loop, the fixture light level may be accurately maintained at any desired value substantially regardless of any changes in magnitude of power line voltage and/or in lamp efficacies. The inverter's positive feedback is attained by way of saturable current transformer means, and control of inverter frequency is attained by providing more or less heat to the saturable magnetic material of the current transformer means, thereby correspondingly to decrease or increase the saturation limits of this magnetic material; which, in turn, correspondingly increases or decreases the frequency of inverter oscillation.
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BACKGROUND OF THE INVENTION
This a continuation of application Ser. No. 549,031, which in turn is a continuation-in-part of applicants' copending application Ser. No. 298,822, filed Oct. 19, 1972 both abandoned.
1. Field of the Invention
This invention relates to a method of increasing the sulfur oxide absorption rate as well as the available percentage of lime used as absorbent and also preventing the formation of a scale, in a process for removing sulfur oxide from waste flue gases, using lime as absorbent.
2. Description of the Prior Art
For the removal of sulfur oxide from combustion gases which is the major element for air pollution, a process using as absorbent a suspension of lime which is easy to procure and inexpensive, is quite advantageous. However, in order to operate this process economically, it is necessary to increase the reaction ratio between the lime in the liquid absorbent and the sulfur oxide, i.e., the available percentage of the lime, concurrently with increasing the sulfur oxide absorption rate. Theoretically speaking, the amount of lime necessary for the absorption of sulfur oxide is stoichiometrically equivalent to the amount of sulfur oxide contained in a waste flue gas to be treated, but in practice a considerably large amount of lime in excess of the stoichiometrical equivalent mentioned above is required for obtaining a high absorption rate of sulfur oxide by washing the waste flue gas containing the sulfur oxide at a low concentration, by reason of the contact efficiency in a gas-liquid-solid contacting apparatus used and the solid elution rate. Accordingly, the liquid discharged from the absorbing apparatus contains a considerable amount of unreacted lime. This not only is disadvantageous economically but also, where it is desired to recover gypsum from the used liquid absorbent, necessitates the additional step of converting the unreacted lime into a sulfate or sulfite by either neutralizing it with sulfuric acid or reacting it with sulfue oxide gas of high concentration, before it is delivered to a gypsum recovery step. In the process of this invention, the absorption step is divided into two stages and each of the two stages is operated in such a manner that a circulating liquid absorbent may be maintained at a prescribed lime concentration, whereby the above-described disadvantages of the conventional process are obviated and the formation of a scale in the absorbing device is avoided, which has been a problem in the conventional process.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a wet waste flue gas sulfurizing process using lime as absorbent, wherein a sulfur oxide-containing waste flue gas is washed with a liquid absorbent containing calcium hydroxide or calcium carbonate for the purpose of removing the sulfur oxide from said waste flue gas, characterized in that an absorbing device is divided into two stages, i.e. a former stage absorbing device and a latter stage absorbing device, arranged in tandem with respect to the waste flue gas flow and the liquid absorbent is circulated in the former stage absorbing device at a lime available percentage of more than 69% and in the latter stage absorbing device at a lime available percentage of 85-95%.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1, 4 and 5 are schematic diagrams respectively showing modes of practice of the process according to this invention; and
FIGS. 2 and 3 are diagrams graphically illustrating the effects of the process of this invention respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A mode of practice of the process of this invention will be practically described hereunder with reference to FIG. 1.
A sulfur oxide-containing waste flue gas (1) at a temperature of about 140° C. is introduced into a gas cooling tower 1, in which it is contacted by water which is supplied by a pump 5 and sprayed from a nozzle, and thereby is humidized and cooled to about 55° C. The flue gas thus humidized and cooled is fed into a former stage absorbing device 2 along a line 2. Part of the water circulating in the gas cooling tower 1 is discharged from the absorbing system to the outside to purge dusts collected from the gas, as indicated at 8, and fresh water is supplied into the tower to make up the amounts of the purged water and evaporating water, as indicated at 6. The gas introduced into the former stage absorbing device 2 is washed therein with a lime-containing absorbing liquid supplied through a pump 7, whereby the sulfur oxide contained in the gas is partially removed therefrom. Thereafter, the gas is led into a latter stage absorbing device 3. In the latter stage absorbing device 8, as in the former stage absorbing device 2, the gas is washed with the lime-containing absorbing liquid, whereby the remaining part of the sulfur oxide contained in said gas is absorbed by said absorbing liquid and removed therefrom. The gas leaving the latter stage absorbing device, which is substantially free of sulfur oxide, is passed through a mist separator 4 as indicated at 4 to have a mist separated therefrom and the resultant clean gas is delivered to a chimney as indicated at 5. Each of the former and latter absorbing devices is provided therein with means, such as a filler, which is generally used industrially, to achieve effective contact between the gas and absorbing liquid, and also has a demister provided therein as required to separate the mist from the gas.
Now, the flow of the absorbing liquid will be described First of all, a finely divided lime material 9, such as powdered quick lime, slaked lime or limestone, and water 10 are supplied into an absorbent preparation tank 11 and mixed therein with stirring to form a slurry. The slurry thus formed is supplied into an absorbing liquid circulation tank 9 of the latter stage absorbing device through a pump 10 as indicated at 11, and then the absorbing liquid is supplied into the latter stage absorbing device 3 thorough a pump 8 as indicated at 12. The absorbing liquid, after reaction with the sulfur oxide contained in the gas within the latter stage absorbing device, is returned to the absorbing liquid circulation tank 9 and again recycled into the latter stage absorbing device 3 through the pump 8. During this period, the major part of the lime in the absorbing liquid is converted into calcium sulfite by the reaction with sulfur oxide. Part of the absorbing liquid is withdrawn from this circulation system and fed into an absorbing liquid circulation tank 6 of the former stage absorbing device as indicated at 13. The absorbing liquid supplied into the absorbing liquid circulation tank 6 is circulated through a pump 7, the former stage absorbing device 2 and the absorbing liquid circulation tank 6, as in case of the latter stage absorbing device, and during this period, the unreacted lime contained in the absorbing liquid supplied from the circulation system of the latter stage absorbing device is converted into calcium sulfite. The calcium sulfite in the absorbing liquid circulating in the former and latter stage absorbing device is partially oxidized into calcium sulfate, depending upon the sulfur oxide concentration and oxygen concentration in the waste flue gas being treated and the pH value of the absorbing liquid. In the manner described, the unreacted lime is subtantially removed from the absorbing liquid and the absorbing liquid substantially free of unreacted lime is withdrawn from the circulation system and delivered to a gypsum recovery step as indicated at 15. In the gypsum recovery step, gypsum is recovered from the used absorbing liquid through the usual steps of pH adjustment, oxidation and filtration.
A waste flue gas from the combustion of heavy oil was treated by the same system as described above, using a packed tower having plates assembled therein in the shape of a lattice, for each of the former and latter stage absorbing devices. Table 1 shows the values actually measured in the treatment of the waste flue gas.
Table 1______________________________________Amount of gas (m.sup.3 /h) 2,000 2,000Amount of slurry circulating in absorbing device 10 14(m.sup.3 /h)Concentration of slurry (wt%) 6 6 Waste flue Inlet SO.sub.2 (ppm) 2,095 1,110Former gas Outlet SO.sub.2 (ppm) 1,704 1,028______________________________________stage pH 3.9 4.0absorbing Absorbing CaCO.sub.3 (mol/l) 0.001> 0.001>device liquid CaSO.sub.3 . 1/2H.sub.2 O (mol/l) 0.143 0.143 CaSO.sub.4 . 2H.sub.2 O (mol/l) 0.354 0.354______________________________________ Waste flue Inlet SO.sub.2 (ppm) 1,704 1,023Latter gas Outlet SO.sub.2 (ppm) 216 38______________________________________stage pH 7 7absorbing Absorbing CaCO.sub.3 (mol/l) 0.035 0.032device liquid CaSO.sub.3 . 1/2H.sub.2 O (mol/l) 0.24 0.199 CaSO.sub.4. 2H.sub.2 O (mol/l) 0.25 0.279______________________________________Sum- SO.sub.2 absorption rate (%) 90.8 96.7mary Lime available percentage (%) 100 100______________________________________
As shown, the lime available percentage was 100% and the sulfur oxide absorption rate was higher than 90%, and the formation or deposition of a scale within the absorbing devices was not observed at all.
The characteristic features of the process of this invention will be described in greater detail hereunder: The first feature lies in overcoming the trouble caused by the attachment of the scale formed in the treatment of a sulfur oxide-containing gas with a lime slurry by an entirely novel method. In the past, it has generally been believed that the formation of a scale is attributable to the fact that an absorbing liquid is excessively saturated with gypsum as a result of a calcium sulfite in the absorbing liquid being oxidized with oxygen contained in the gas and converted into calcium sulfate, and said calcium sulfate precipitates to form the scale. Therefore, an attempt has been made to lower the degree of excessive saturation of the absorbing liquid with gypsum, as a countermeasure to the scale problem, and it is a conventionally known method to add seeds of gypsum to the circulating absorbing liquid. It is also known, as means for increasing the effect of the gypsum seeds added, to retain the gypsum seeds for a certain period of time in the absorbing liquid after said seeds have been added. What is important to note here is that the present inventors have found through experiments that there are two types of scale, namely a relatively hard scale consisting of gypsum as mentioned above and a relatively soft scale consisting of a mixture of calcium carbonate, calcium sulfite and gypsum. The formation of the former hard scale can be suppressed as by the addition of gypsum seeds described above, but the precipitation of the latter scale is unavoidable and only encouraging the flow of circulating absorbing liquid is insufficient to eliminate the scale. In the past, an absorbing device has become inoperable after a few days of operation due to the soft scale deposited on the inner surface thereof, and therefore, it has been necessary, when the absorbing device became inoperable, to open the device, remove the deposited scale and further wash the inner surface of the device with a liquid chemical. The present inventors have found the following fact concerning the removal of such soft scale. Namely, the present inventors have found that, by operating the absorbing device while maintaining the pH value of an absorbing liquid, circulating in said absorbing device, not higher than 7.0 but not lower than 6.5, the absorbing device can continuously be operated without allowing precipitation or attachment of the scale and with a sulfur oxide removing rate substantially the same as when the pH value is near 1111.This is because, when the pH value of the absorbing liquid becomes small, so that said absorbing liquid is reduced in viscosity and hence in adhesiveness. It should be noted, however, that the pH of the absorbing liquid must be maintained within the range specified above as excessively low pH will result in reduction of the sulfur oxide absorption rate.
Another feature of the invention lies in that the available percentage of the lime used is increased to near 100% and the pH value of the absorbing liquid is lowered to a level at which gypsum can be advantageously recovered. Namely, in the conventional process a consideration has generally been given only to increasing the sulfur oxide removing rate and, for waste flue gases maintaining sulfur oxide at relatively low concentrations, which are regarded as a source of air pollution, it has been believed difficult to increase the available percentage of lime used for the removal of sulfur oxide and to lower the pH value of the absorbing liquid to a desired level. Therefore, in the conventional process there has been employed a method in which sulfurous acid gas of high concentration is introduced into a desulfurization system from the outside to be absorbed by the absorbing liquid, so as to eliminate the unreacted lime and adjust the pH value of said absorbing liquid to the desired level.
In the process of this invention, as described above with reference to FIG. 1, the absorbing device is divided into the former stage absorbing device 2 and latter stage absorbing device 3, and a waste flue gas to be treated is passed successively in said first and second stage absorbing devices 2 and 3, while an absorbing liquid containing a lime slurry is circulated first in the latter stage absorbing device 3 and then in the former stage absorbing device 2, and furthermore the lime available percentage of the absorbing liquid is regulated so that it is between 85-95% in said latter stage absorbing device and more than 96% in said former stage absorbing device so that absorption of sulfur oxide may be mainly carried out in the latter stage absorbing device and reaction of the unreacted lime in the former stage absorbing device. Thus, it has become possible to maintain concurrently both a high sulfur oxide absorption rate and a high lime available percentage. As may be understood from FIG. 3, substantially no unreacted lime remains in the absorbing liquid when the process is carried out while maintaining the pH value of the absorbing liquid in the former stage absorbing device within the range of 3.5-4.0 . Excessive lowering of the pH value is undesirable because of the increasing corrosive action of the absorbing liquid.
Another advantage of dividing the absorbing device into two stages is that, in achieving both a high sulfur oxide absorption rate and a high lime available percentage concurrently, the height of the towery absorbing devices can be drastically reduced as compared with the case of using a single absorbing device. For instance, in treating a combustion gas containing sulfur oxide at a concentration of 1,000 ppm, using the lattice type packed tower and with a liquid-to-gas ratio of 7 l/m 3 and a gas flow rate of 3 m/sec., the effective height of the scrubber necessary to obtain 90% of sulfur oxide absorption rate and 96% of lime available percentage is 17.3 m when said scrubber consists of a single absorbing tower, and is only 11 m in total when said scrubber is divided into two stage absorbing towers.
In short, it is only essential in the present invention to divide the absorbing step into two stages operated successively with respect to the flow of gas and to maintain the lime available percentage of the circulating absorbing liquid within the range of more than 96% in the former stage and at a percentage of 85-95% in the latter stage. Therefore, the process of this invention may be operated, besides the type of apparatus described hereinbefore, by an apparatus as shown in FIG. 4 in which only one absorbing device is used and the interior of said absorbing device is divided into two sections for first and second stages of absorption, or by an apparatus as shown in FIG. 5, depending upon the sulfur oxide concentration in a waste flue gas to be treated, in which the inlet gas for a first stage absorbing device is diverged into two flows and one of them is introduced directly into a latter stage absorbing device and the other one of them into said latter stage absorbing device via the former stage absorbing device.
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A wet waste flue gas desulfurizing process using lime as absorbent, wherein a sulfur oxide-containing waste flue gas is washed with a liquid absorbent containing calcium hydroxide or calcium carbonate for the purpose of removing the sulfur oxide from said waste flue gas, characterized in that an absorbing device is divided into two stages, i.e. a former stage absorbing device and a latter stage absorbing device, arranged in tandem with respect to the flow of said waste flue gas, and the liquid absorbent is circulated in the former stage absorbing device at a lime available percentage of more than 96% and in the latter stage absorbing device at a lime available percentage of 85 - 95%.
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FIELD OF THE INVENTION
[0001] The present invention pertains to the art of cup holders. More specifically, it pertains to a cup holder that can be fastened onto an extendible luggage handle and is flexible so as to maintain the cup being held in upright orientation to prevent spilling.
BACKGROUND INFORMATION
[0002] Devices for holding beverage cups have become popular in recent decades and can be found mounted in cars, on golf carts, and on furniture. Many cup holder designs have been implemented.
[0003] As an example, a self-leveling cup holder has been proposed, which has a rigid structure for receiving a beverage container and which clamps to a golf cart handle. The cup holder uses a mechanical swivel structure to maintain the beverage in a nominally level state when the golf cart handle is moved. For further details, refer to U.S. Pat. No. 3,269,683 to Shinaver.
[0004] A self-leveling cup holder that fastens to a rolling luggage case would be useful. Although a cup holder like that disclosed by Shinaver may be well adapted to use on a golf cart, it is ill suited to use on a rolling luggage where it would need to be readily removable from the handle (since the handles on rolling luggage tend to be retractable), yet provide secure support when installed. A cup holder than can be easily attached and removed from the handle of a piece of wheeled luggage has been proposed. Although one embodiment discloses a pivot means, it does not appear to be self-leveling. For further details, refer to U.S. Pat. No. 6,390,431 to Ott.
[0005] A cup holder has been proposed that is self-leveling via a mechanical pivot and can be affixed to wheeled luggage. For further details, refer to U.S. Patent Application Publication No. 2006/0037825 by Dayton et al. The various embodiments of the Dayton et al. cup holder are either integrated into the collapsible handle or into the frame of the luggage. Such integration would require substantial structural accommodations (drilling of holes, assembly concurrent with manufacture of the luggage, etc.) and does not appear to be suitable for retrofitting to existing luggage without substantial effort.
[0006] In the context of modern travel and business, what is needed is a self-leveling cup holder that can be removably affixed to a piece of wheeled luggage in a way that both the fixing and the removal can be accomplished quickly and easily and can be easily stored when not in use. This will avoid any need for substantial modification of existing luggage designs and will avoid the hassle and time expense of installation and removal that are non trivial.
SUMMARY OF THE INVENTION
[0007] The present invention provides a way to support a beverage container that avoids the problems described above. The present invention may be comprised as a self-leveling cup holder that can be removably affixed to a piece of wheeled luggage in a way that both the fixing and the removal can be accomplished quickly and easily.
[0008] According to embodiments of the present invention a cup holder is provided. One part of the cup holder is a truncated hollow cone sized to hold a typical beverage cup. Another part of the cup holder is a handle sleeve sized to fit over and resiliently hug the top of an extended handle of the sort typically found on rolling luggage. When in use, the cup holder is mounted onto the top of the extended handle of a piece of rolling luggage and holds a cup of liquid while the luggage is being pulled around. The cup holder is constructed from a stretchy fabric so that the handle sleeve resiliently grips the top of the luggage handle. The flexibility of the fabric material provides the flexibility for the truncated hollow cone portion that supports the cup is free to move relative to the luggage handle so that a self-leveling action is provided without need of a mechanical hinge.
[0009] One aspect of the present invention is the combination of a flexible structure that fits over and resiliently hugs the top of an extended luggage handle.
[0010] Another aspect of the present invention is structure that supports a cup and is free to rotate relative to a supporting member so as to effect a self-leveling action without need of a mechanical pivot structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates a perspective view of a cup holder according to a first embodiment of the present invention being used in combination with wheeled luggage.
[0012] FIG. 2 illustrates a detail view of the cup holder according to the first embodiment, showing relationship of the cup holder to an extendible handle.
[0013] FIG. 3 illustrates a perspective view of a cup holder according to the first embodiment.
[0014] FIG. 4 illustrates a front elevation view of a cup holder according to the first embodiment.
[0015] FIG. 5 illustrates a side elevation view of a cup holder according to the first embodiment.
[0016] FIG. 6 illustrates a plan view of a cup holder according to the first embodiment.
[0017] FIG. 7 illustrates a perspective view of a cup holder according to a second embodiment of the present invention being used in combination with wheeled luggage.
[0018] FIG. 8 illustrates a detail view of the cup holder according to the second embodiment, showing relationship of the cup holder to an extendible handle.
[0019] FIG. 9 illustrates a perspective view of a cup holder according to the second embodiment.
[0020] FIG. 10 illustrates a front elevation view of a cup holder according to the second embodiment.
[0021] FIG. 11 illustrates a side elevation view of a cup holder according to the second embodiment.
[0022] FIG. 12 illustrates a plan view of a cup holder according to the second embodiment.
[0023] FIG. 13 illustrates a perspective view of a cup holder according to a third embodiment of the present invention being used in combination with wheeled luggage.
[0024] FIG. 14 illustrates a detail view of the cup holder according to the third embodiment, showing relationship of the cup holder to an extendible handle.
[0025] FIG. 15 illustrates a perspective view of a cup holder according to the third embodiment.
[0026] FIG. 16 illustrates a front elevation view of a cup holder according to the third embodiment.
[0027] FIG. 17 illustrates a side elevation view of a cup holder according to the third embodiment.
[0028] FIG. 18 illustrates a plan view of a cup holder according to the third embodiment.
[0029] FIG. 19 illustrates a side elevation view of a cup holder with an optional feature of the first embodiment.
[0030] FIG. 20 illustrates a side elevation view of a cup holder with another optional feature of the first embodiment.
DETAILED DESCRIPTION
[0031] The present invention provides a way to carry a beverage cup supported on the collapsible handle of a wheeled piece of luggage. This serves as a convenience for travelers and business people who may wish to carry around a drink while at the same time keep their hands free to do other tasks. Cup holders embodied according to the present invention are formed of flexible materials that permit them to be flattened and stowed inside a coat pocket or an exterior luggage pocket. The fabric-backed polymer foam sheeting (usually formed from polychloroprene) commonly referred to as “neoprene” has been successfully implemented as a suitable material for making the cup holders. Neoprene has the extra advantage of providing an added degree of insulation to help maintain hot or cold temperature of the beverage being carried. Another advantage of using neoprene to form the cup holder is that it may provide a positive grip when in contact with a luggage handle. Neoprene, as intended by this disclosure, includes (without limitation) chloroprene rubber (known in the art as CR and commonly used for manufacture of wet suits), styrene butadiene rubber (known in the art as SBR and commonly used for accessories), and chloroprene/styrene-butadiene blend (known in the art as CS) that is typically 30% CR and 70% SBR.
[0032] The cup holders may also be advantageously formed of leather, polymer (e.g., butyl rubber), or any of various textiles such as canvas (e.g., cotton or acrylic), spandex (e.g., Lycra®), nylon (e.g., Cordura®), and microfiber. Various types of paper, including card stock, are considered to be appropriate for embodying the cup holders. Generally, suitable materials include any fabric or flexible material, natural or man-made, that can be sewn, glued, bonded, hemmed, selvedged, piped, cut, imprinted, embroidered, welded (chemically, thermally, or ultrasonically), beaded, melded, bordered, or stamped.
[0033] A first embodiment of the present invention is illustrated in FIG. 1 , which shows a piece of rolling luggage 10 with its handle 12 extended. A cup holder 100 according to the first embodiment of the invention is shown engaged atop the extended handle 12 , with the self-leveling aspect being portrayed by the relative angle of the upright cup holder 100 with respect to the tilted handle 12 .
[0034] The relationship of the cup holder 100 to the top end of the extended handle 12 is illustrated in FIG. 2 , with the handle being shown in phantom. A cup support 110 maintains a nominally upright orientation at a relative angle with respect to the tilted handle 12 . The cup support 110 has freedom of rotational movement with respect to a handle sleeve 140 , which surrounds and resiliently grips onto the upper end of the tilted handle 12 .
[0035] A pair of opposed sleeve channels 142 wrap around and grip parallel sides of the extended handle 12 . The freedom of rotational movement of the cup support 110 relative to the handle sleeve 140 is afforded by twisting of the webbing 144 that extends between opposed sides of the support 110 and the lower ends of the sleeve channels 142 . A top channel 146 covers the portion of the hand grip portion of the handle 12 and extends between the two sleeve channels 142 , and may be open at the ends to accommodate different sized handles.
[0036] As can be seen in FIG. 3 , the webbing 144 , the sleeve channels 142 , and the top channel 146 are formed together as a continuous structure that is connected to opposed sides of the top of the cup support 110 . The opposed sleeve channels 142 are also joined together at their bottom ends by a strap 150 which urges the sleeve channels 142 toward one another when the handle sleeve 140 is slipped over an extended luggage handle 12 . The webbing 144 attaches to the cup support 110 at seams 118 on opposed sides of the cup support 110 . The strap 150 may be alternately embodied to be split with Velcro elements to make it adjustable to adjust for different widths of handles 12 .
[0037] An oblong aperture 148 is formed centered at the midpoint of the top channel 146 , at the deepest part of the channel. The aperture 148 is sized to accommodate a lock release push button that is located in the middle of the top of the handle of many (but not all) wheeled luggage cases.
[0038] The cup support 110 is shaped as a hollow truncated cone, with the bottom end 112 being slightly narrower than the top end 114 . A bottom support strap 116 extends across the bottom of the cup support 110 and is permanently affixed at opposed sides of the cup support 110 . The bottom support strap 116 is an optional feature that is useful to prevent small beverage containers from becoming stuck in the cup support 110 with the top of the beverage container not extending above the top end 114 of the cup support 110 , or from passing entirely through an open bottom end 112 . Alternatively, the cup support 110 may be embodied having a solid bottom rather than a strap, or as a solid bottom with a hole. As shown in FIG. 3 , the strap 116 is shown as bowing downward from the bottom of the cup support 110 , however, this is not meant as a limitation and the strap 116 may alternatively be fastened so as to bow upward from the bottom edge of the cup support 110 .
[0039] Although cup support 110 has been illustrated as being solid all the way around, it may be alternately embodied having perforations. According to one alternate embodiment, elongated perforations are formed in the cup support 110 to enable it to roll up easily so the handle 12 can be stowed with the cup holder remaining attached to the handle 12 .
[0040] Referring to FIG. 4 , a front plan view of the cup holder 100 shows a hand hold opening 160 that is formed by the space between the opposed sleeve channels 142 and between the top channel 146 and the cup support 110 and strap 150 . The hand hold opening 160 is sized to accommodate an adult hand fitting therethrough.
[0041] Referring to FIG. 5 , gather seams 152 (refer also to FIG. 4 ) are formed in a lower portion of each of the opposed sleeve channels 142 to narrow the overall width of the bottom end of the handle sleeve 140 . The use of the gather seams 152 to narrow the handle sleeve 140 serves to enhance the resilient griping of the handle sleeve onto an extended luggage handle 12 , while leaving the remaining, upper portion of the handle sleeve 140 to grip the handle 12 more loosely to keep the cup holder 100 from being too inconvenient during application and removal due to excessive sliding friction forces.
[0042] The rearward offset of the handle sleeve 140 with respect to the cup support 110 is illustrated by the plan view of FIG. 6 .
[0043] As an optional feature of the first embodiment, the ends of the top channel 146 may be open to allow for oversized handles.
[0044] Referring to FIG. 19 , another optional feature of the first embodiment is a pocket 170 on the handle sleeve 140 , on the back side in the illustrated example, which is sized to hold a boarding pass or a paperback book.
[0045] Referring to FIG. 20 , yet another optional feature of the first embodiment is an elastic pen holder sleeve 180 fixed to a side of the handle sleeve 140 . The pen holder sleeve is sized to resiliently grip the shaft of a pen. As an example, a piece of elastic fabric is seamed down two sides to form the resilient pen holder sleeve 180 .
[0046] A further optional feature of the first embodiment is a hook and loop fastener, one element of which is affixed to the handle sleeve 140 , for attaching accessories such as a cell phone holder or a baby bottle holder.
[0047] A second embodiment of the present invention is illustrated in FIG. 7 . A piece of rolling luggage 10 is shown with its handle 12 extended and having a cup holder 700 according to the second embodiment of the invention engaged atop the extended handle 12 , with the self-leveling aspect being portrayed by the relative angle of the upright cup holder 700 with respect to the tilted handle 12 .
[0048] The relationship of the cup holder 700 to the top end of the extended handle 12 is illustrated in FIG. 8 , with the handle being shown in phantom. A cup support 710 maintains a nominally upright orientation at a relative angle with respect to the tilted handle 12 . The cup support 710 has freedom of rotational movement with respect to a handle wrap 740 , which surrounds and resiliently grips onto the upper end 14 of the tilted handle 12 .
[0049] A pair of opposed support straps 742 extend from opposed ends of the handle wrap 740 wrapped around the extended handle's upper end 14 , to opposed sides of the upper end of the cup support 710 . Swing arresting straps 752 , extend outwardly from opposed sides of the cup support 710 and have sufficient length to loop around a member of the handle 12 and fasten the free end to the side of the cup support 710 , or to themselves, with a hook loop fastener (refer to FIG. 11 ). The freedom of rotational movement of the cup support 710 relative to the handle wrap 740 is afforded by twisting of the support straps 742 at the lower ends 746 and twisting of the swing arresting straps 752 . This makes the effective pivot axis of the cup holder 700 be adjacent the top edge of the cup support 710 .
[0050] As can be seen in FIG. 9 , the support straps 742 and the handle wrap 740 are formed together as a continuous structure that is connected to opposed sides of the top of the cup support 710 . An oblong aperture 748 is formed centered at the midpoint of the handle wrap 740 . The aperture 748 is sized to accommodate a lock release push button that is located in the middle of the top of the handle of many (but not all) wheeled luggage cases.
[0051] The cup support 710 is shaped as a hollow truncated cone, with the bottom end 712 being slightly narrower than the top end 714 . Although no bottom support strap structure is illustrated as is shown in the first embodiment (refer to FIGS. 2-6 ), such an optional structure may be usefully implemented with the second embodiment in a manner similar to that shown and described with respect to the first embodiment, or the cup support 710 may have a solid bottom, with or without a hole. The swing arresting straps 752 are shown as extending outwardly from opposed sides of the cup support 710 . The swing arresting straps 752 are not required for practice of the invention, but can enhance usefulness of the second embodiment by moderating the degree to which the cup support 710 swings back and forth.
[0052] Referring to FIG. 10 , a front plan view of the cup holder 700 shows a hand hold opening 760 that is formed by the space between the opposed support straps 742 and between the handle wrap 740 and the cup support 710 . The hand hold opening 760 is sized to accommodate an adult hand fitting therethrough.
[0053] Referring to FIG. 11 , a hook and loop fastener 754 for securing the handle wrap 740 is shown. Hook and loop faster elements 756 , 758 for the swing arresting straps 752 are illustrated (refer also to FIG. 12 ), with elements 756 on the ends of the straps 752 and elements 758 on the sides of the cup support 710 . The hook and loop fasteners provided by hook and loop elements 756 , 758 are used to secure the swing arresting straps 752 in place when looped around members of the extended luggage handle 12 . Generally, the fastening elements 754 , 756 , 758 are not limited to hook and loop type, and any type of soft or hard fastener may be used, including (but without limitation) snaps, buttons, zippers, or hooks.
[0054] As shown in FIGS. 11 and 12 , fastener elements 758 are shown as being located on the outer surface of the cup support 710 . However, this illustrated placement is not meant as a limitations, and fastener elements 758 may alternatively be placed on the strap 752 covering the area starting from the cup support 710 and ending at a point near the other hoot and loop fastener element 756 .
[0055] As mentioned above, use of the swing arresting straps 752 is not strictly necessary for practice of the invention and may be left to dangle from the side of the cup support 710 , or may be omitted entirely from articles manufactured (refer to the third embodiment, described below). The swing arresting straps 752 may be made long so as to permit substantial swing of the cup support 710 , or may be made shorter so as to restrain the cup support so that the entirety of its rotational freedom is at the lower ends 746 of the support straps 742 .
[0056] The alignment of the handle wrap 740 with respect to the cup support 710 is illustrated by the plan view of FIG. 12 .
[0057] A third embodiment of the present invention is illustrated in FIG. 13 . A piece of rolling luggage 10 is shown with its handle 12 extended and having a cup holder 800 according to the second embodiment of the invention engaged atop the extended handle 12 , with the self-leveling aspect being portrayed by the relative angle of the upright cup holder 800 with respect to the tilted handle 12 .
[0058] The relationship of the cup holder 800 to the top end of the extended handle 12 is illustrated in FIG. 14 , with the handle being shown in phantom. A cup support 810 maintains a nominally upright orientation at a relative angle with respect to the tilted handle 12 . The cup support 810 has freedom of rotational movement with respect to a handle wrap 840 , which surrounds and resiliently grips onto the upper end 14 of the tilted handle 12 .
[0059] A pair of opposed support straps 842 extend from opposed ends of the handle wrap 840 wrapped around the extended handle's upper end 14 , to opposed sides of the upper end of the cup support 810 . The freedom of rotational movement of the cup support 810 relative to the handle wrap 840 is afforded by twisting of the support straps 842 at the upper ends 844 and, to a lesser extent, the lower ends 846 . This makes the effective pivot axis of the cup holder 800 be adjacent the bottom end of the handle wrap 840 , a result primarily of the twisting of the upper ends 844 of the support straps 842 .
[0060] As can be seen in FIG. 15 , the support straps 842 and the handle wrap 840 are formed together as a continuous structure that is connected to opposed sides of the top of the cup support 810 . An oblong aperture 848 is formed centered at the midpoint of the handle wrap 840 . The aperture 848 is sized to accommodate a lock release push button that is located in the middle of the top of the handle of many (but not all) wheeled luggage cases.
[0061] The cup support 810 is shaped as a hollow truncated cone, with the bottom end 812 being slightly narrower than the top end 814 . Although no bottom support strap structure is illustrated as is shown in the first embodiment (refer to FIGS. 2-6 ), such an optional structure may be usefully implemented with the second embodiment in a manner similar to that shown and described with respect to the first embodiment, or the cup support 810 may have a solid bottom, with or without a hole.
[0062] Referring to FIG. 16 , a front plan view of the cup holder 800 shows a hand hold opening 860 that is formed by the space between the opposed support straps 842 and between the handle wrap 840 and the cup support 810 . The hand hold opening 860 is sized to accommodate an adult hand fitting therethrough.
[0063] Referring to FIG. 17 , a hook and loop fastener 854 for securing the handle wrap 840 is shown. Generally, the fastening element 854 is not limited to hook and loop type, and any type of soft or hard fastener may be used, including (but without limitation) snaps, buttons, zippers, or hooks.
[0064] The alignment of the handle wrap 840 with respect to the cup support 810 is illustrated by the plan view of FIG. 18 .
[0065] An important advantage of the present invention is that cup holders using this technology are easy to apply to a luggage handle and are also easy to remove. This is a very useful convenience.
[0066] The materials used permit natural rotation of the cup support when the luggage is tilted as when it is being moved. This keeps the beverage level as it is affected by the force of gravity. The use of fabric (or leather) flexibility to supplant a mechanical pivot structure has advantages. By eliminating any mechanical pivot from the cup holder, the reliability of the cup holder is improved because there are no moving parts to fail. Eliminating any mechanical pivot from the cup holder also improves the manufacturing cost of the cup holder by reducing inventory requirement of a relatively expensive part.
[0067] The all-fabric composition that is possible according to the present invention has the advantage of making the cup holder fully washable via machine laundry. The use of flexible materials to embody the cup holder make it easy to store (i.e., can be stuffed in a pocket when not in use) and lightweight. The lack of any sharp edges points makes the cup holder very safe. By using a stretchy fabric the cup holder can conform to fit a wide variety of sizes and shapes of luggage handles, and can conform to fit a wide variety of sizes and shapes of beverage containers.
[0068] The beverage container is protected to some degree from jarring since the flexible material of the cup holder absorbs shock, and the cup support is protected from direct force on either side by the telescoping risers of the luggage handle.
[0069] Various embodiments of self-leveling cup holders have been described. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the scope of the invention disclosed and that the examples and embodiments described herein are in all respects illustrative and not restrictive. Those skilled in the art of the present invention will recognize that other embodiments using the concepts described herein are also possible. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an,” or “the” is not to be construed as limiting the element to the singular.
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A cup holder is mountable onto the top of an extendable handle projecting from the top of a piece of wheeled luggage. The cup holder holds a cup of liquid while the luggage is being pulled around. The cup holder is constructed from a stretchy fabric with a handle sleeve that resiliently grips the top of the extended luggage handle. The flexibility of the fabric material provides the cup support, in the form of a truncated hollow cone, with a way of rotating freely with respect to the luggage handle so that a self-leveling action is provided without need of a mechanical hinge.
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This application claims the priority under 35 U.S.C. 119(e)(1) of U.S. provisional application No. 60/187,260, filed on Mar. 6, 2000.
FIELD OF THE INVENTION
The invention relates generally to wireless communications and, more particularly, to wireless communications that utilize retransmissions.
BACKGROUND OF THE INVENTION
Present telecommunication system technology includes a wide variety of wireless networking systems associated with both voice and data communications. An overview of several of these wireless networking systems is presented by Amitava Dutta-Roy, Communications Networks for Homes , IEEE Spectrum, pg. 26, December 1999. Therein, Dutta-Roy discusses several communication protocols in the 2.4 GHz band, including IEEE 802.11 direct-sequence spread spectrum (DSSS) and frequency-hopping (FHSS) protocols. A disadvantage of these protocols is the high overhead associated with their implementation. A less complex wireless protocol known as Shared Wireless Access Protocol (SWAP) also operates in the 2.4 GHz band. This protocol has been developed by the HomeRF Working Group and is supported by North American communications companies. The SWAP protocol uses frequency-hopping spread spectrum technology to produce a data rate of 1 Mb/sec. Another less complex protocol is named Bluetooth after a 10 th century Scandinavian king who united several Danish kingdoms. This protocol also operates in the 2.4 GHz band and advantageously offers short-range wireless communication between Bluetooth devices without the need for a central network.
The Bluetooth protocol provides a 1 Mb/sec data rate with low energy consumption for battery powered devices operating in the 2.4 GHz ISM (industrial, scientific, medical) band. The current Bluetooth protocol provides a 10-meter range and a maximum asymmetric data transfer rate of 723 kb/sec. The protocol supports a maximum of three voice channels for synchronous, CVSD-encoded transmission at 64 kb/sec. The Bluetooth protocol treats all radios as peer units except for a unique 48-bit address. At the start of any connection, the initiating unit is a temporary master. This temporary assignment, however, may change after initial communications are established. Each master may have active connections of up to seven slaves. Such a connection between a master and one or more slaves forms a “piconet.” Link management allows communication between piconets, thereby forming “scatternets.” Typical Bluetooth master devices include cordless phone base stations, local area network (LAN) access points, laptop computers, or bridges to other networks. Bluetooth slave devices may include cordless handsets, cell phones, headsets, personal digital assistants, digital cameras, or computer peripherals such as printers, scanners, fax machines and other devices.
The Bluetooth protocol uses time-division duplex (TDD) to support bi-directional communication. Frequency hopping permits operation in noisy environments and permits multiple piconets to exist in close proximity. The frequency hopping scheme permits up to 1600 hops per second over 79 1-MHZ channels or the entire 2.4 GHz ISM spectrum. Various error correcting schemes permit data packet protection by ⅓ and ⅔ rate forward error correction. Further, Bluetooth uses retransmission of packets for guaranteed reliability. These schemes help correct data errors, but at the expense of throughput.
The Bluetooth protocol is specified in detail in Specification of the Bluetooth System , Version 1.0A, Jul. 26, 1999, which is incorporated herein by reference.
For speech transmissions, the Bluetooth specification calls for 64 kilobits/second CVSD speech coding on an SCO (Synchronous Connection-Oriented) link. This means that a Bluetooth system can support up to three voice channels for up to three users. On the other hand, according to known techniques, the speech can be coded using a lower rate coder, and can then be treated as data for transmission on Bluetooth ACL (Asynchronous Connection-Less) links. In this fashion, more voice channels and users can be supported. Also, ACL links allow retransmission of packets, which can provide enhanced quality relative to SCO to links which do not allow retransmission of packets.
The present invention recognizes the desireability of further improving the quality of speech transmission on Bluetooth ACL links and other wireless communication links. To this end, the invention advantageously provides for increasing the utilization and effectiveness of retransmission communications by dynamically assigning desired communications to the respective retransmission slots.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 diagrammatically illustrates an exemplary timing arrangement of transmissions and retransmissions in conventional Bluetooth ACL links.
FIG. 2 diagrammatically illustrates an exemplary timing arrangement of transmissions and retransmissions over Bluetooth ACL links according to the present invention.
FIGS. 3–5 diagrammatically illustrate applications of the arrangement of FIG. 2 wherein the amount of retransmissions varies inversely with the number of users.
FIG. 6 diagrammatically illustrates an exemplary application of the arrangement of FIG. 2 wherein the communication direction of the retransmission slots is variable.
FIG. 7 illustrates a further exemplary application of the arrangement of FIG. 2 wherein the same communication is transmitted in two retransmission slots.
FIG. 8 diagrammatically illustrates a further exemplary application of the arrangement of FIG. 2 wherein a single retransmission slot is used for transmission of two separate communications.
FIG. 9 diagrammatically illustrates pertinent portions of exemplary embodiments of the master device illustrated in FIGS. 2–8 .
FIG. 10 illustrates exemplary operations which can be performed by the master device of FIG. 9 .
FIG. 11 diagrammatically illustrates pertinent portions of exemplary embodiments of the slave devices illustrated in FIGS. 2–8 .
FIG. 12 illustrates exemplary operations which can be performed by the slave device of FIG. 11 .
FIGS. 13 and 13A diagrammatically illustrate pertinent portions of further exemplary embodiments of the master device of FIG. 9 .
FIGS. 14 and 14A diagrammatically illustrate pertinent portions of further exemplary embodiments of the slave device of FIG. 11 .
FIG. 15 illustrates exemplary simulation results associated with the embodiments of FIGS. 13 and 14 .
DETAILED DESCRIPTION
FIG. 1 illustrates an exemplary transmission//retransmission timing arrangement associated with transmission of speech in the form of data packets transmitted over Bluetooth ACL links. In the example of FIG. 1 , M represents a Bluetooth master device and S 1 , S 2 and S 3 represent Bluetooth slave devices respectively associated with three users of a Bluetooth system. As illustrated in FIG. 1 , for each slave device there is reserved a master-to-slave transmission time slot, a corresponding slave-to-master transmission time slot, a master-to-slave retransmission time slot and a corresponding slave-to-master retransmission time slot. All of the available time slots in FIG. 1 are thus pre-assigned to the three users associated with slave devices S 1 , S 2 and S 3 .
According to exemplary embodiments of the present invention illustrated generally in FIG. 2 , a master-to-slave transmission time slot and a slave-to-master transmission time slot are pre-assigned for each slave device in a Bluetooth piconet but, advantageously, the retransmission time slots are not pre-assigned, but rather are dynamically assignable by the master device in order to increase the utilization and efficiency of the retransmissions. According to one exemplary embodiment, whose operation is illustrated in FIG. 3 , the first two retransmission time slots of FIG. 1 can be re-assigned as transmission slots, thereby permitting a fourth slave device S 4 to join the piconet. The four remaining retransmission slots in FIG. 3 can then be assigned by the master to those slaves which either require retransmission or need to retransmit. For a slave that needs to receive a retransmission, the master retransmits the packet to the slave, and for a slave that needs to retransmit, the master sends to the slave a packet including a negative acknowledgment (NAK). This is described in more detail below.
FIGS. 4 and 5 illustrate further exemplary applications of the dynamic retransmission time slot assignment illustrated in FIG. 2 . The example of FIG. 4 , taken together with the example of FIG. 3 illustrates a situation wherein, for example, the slave devices S 3 and S 4 of FIG. 3 leave the piconet. In this situation, the transmission slots provided for slaves S 3 and S 4 in FIG. 3 are instead now designated 1 =as retransmission slots, so retransmission begins directly after slave S 2 transmits to the master. Thus, according to the invention, as the size of the piconet decreases, the retransmission capabilities increase.
FIG. 5 , when taken in conjunction with FIG. 4 , illustrates an exemplary situation wherein a slave device S 3 joins the piconet. In this situation, the first two retransmission time slots of FIG. 4 are now designated as transmission time slots to use for transmissions to and from slave S 3 . Referencing FIGS. 3–5 , whenever a slave joins (or leaves) the piconet, the master device M can send to all active slaves a broadcast control packet in one of the retransmission slots (for example the first retransmission slot) including information indicative of when the last transmission slot (or the first retransmission slot) will occur.
FIG. 6 diagrammatically illustrates a further exemplary application of dynamic retransmission slot assignment according to the invention. In the example of FIG. 6 , the second retransmission slot is used to send from the master to slave S 2 a packet including a negative acknowledgment, which indicates that the packet sent from S 2 in the fourth transmission time slot of the transmission period was not correctly received by the master. Referring also to FIG. 1 , the second retransmission slot is conventionally reserved for transmissions from a slave device to the master device, in contrast to the example of FIG. 6 . The third retransmission slot of FIG. 6 is assigned for a retransmission of the aforementioned lost packet from slave S 2 to the master device, whereas the third retransmission slot is conventionally assigned to a transmission from the master device (see also FIG. 1 ). Similarly, the fourth retransmission slot of FIG. 6 is assigned to a transmission from the master to slave S 3 , whereas the fourth retransmission slot of FIG. 1 is conventionally assigned to a slave transmission. Because transmissions from the master device to the slave devices are permitted in retransmission time slots which are conventionally reserved for transmissions from the slave devices to the master device, the slave devices must listen during each retransmission time slot in order to receive their intended packets.
The example of FIG. 7 illustrates a situation where only one packet was lost during the transmission period, namely the packet transmitted by the master to slave S 1 during the first transmission time slot (the slave S 1 having responded with a NAK in the second transmission time slot). Thus, in this example, each of the two retransmission time slots can be assigned for retransmission of the lost packet from the master device to slave S 1 .
According to the Bluetooth specification, a slave device is not allowed to transmit in a given time slot unless the master device addressed that slave device in the previous time slot. However, the master-to-slave link (downlink) and the slave-to-master (uplink) are often not symmetrical. Indeed, it can be expected that sometimes, for example, a master-to-slave packet will arrive correctly, but the corresponding slave-to-master packet will be lost. However, because the slave device cannot transmit unless the master device has addressed it in the previous time slot, the slave device cannot, in conventional operation, retransmit the lost packet to the master device in a given time slot unless the master device sends a corresponding negative acknowledgment to that slave in the previous time slot.
According to the invention, when the master device retransmits a packet to a first slave device during a given retransmission slot, the master device can also advantageously use that retransmitted packet to request a second slave device to retransmit to the master device in the next time slot. So long as there are no more than fifteen slaves in the piconet, the master can use the four TYPE bits defined in the Bluetooth specification to identify which of the slave devices is requested to retransmit during the next time slot. One of the sixteen possible values of the four TYPE bits can be used by the master to signal that it (the master) will transmit in the next retransmission slot, and the other fifteen values can be used to designate which of up to fifteen slave devices is requested to retransmit in the next retransmission slot. The above-described use of a retransmission packet directed to a first slave device to request that a second slave device retransmit in the next slot is illustrated in the example of FIG. 8 .
In FIG. 8 , the master retransmits a packet to slave 1 (in response to a NAK received from slave S 1 in the second transmission slot), and that retransmitted packet includes a request (NAK) for slave 2 to retransmit in the next retransmission time slot. The Bluetooth TYPE bits are available to designate which device is to transmit in the next time slot, because a master-to-slave retransmission packet does not need the TYPE bits to identify its packet type to the receiving slave device. The TYPE bits are not necessary to identify the packet type as a retransmission, because the bit SEQN, as defined in the Bluetooth specification and included in all Bluetooth packets, can be used by a slave device, such as slave S 1 in FIG. 8 , to determine whether the received packet is a retransmission packet or a NAK, which are the only two possibilities for a master-to-slave packet during the retransmission period.
FIG. 9 diagrammatically illustrates pertinent portions of exemplary embodiments of a master device (e.g., a base unit of a cordless phone system) which can perform the operations illustrated in FIGS. 2–8 . The embodiment of FIG. 9 includes a packet processor 51 coupled for bidirectional communications with a communications application 52 and a wireless communications interface 53 . The packet processor 51 can receive communication information from the communications application 52 , and can use well known conventional techniques to assemble the information into appropriate packets for forwarding to the wireless communications interface 53 . The wireless communications interface 53 can use well known conventional techniques to transmit the assembled packets to one or more slave devices via an antenna 54 and a wireless communications link 55 , for example a Bluetooth radio link. Conversely, the wireless communications interface 53 can use conventional techniques to receive packets from one or more slave devices via the wireless communications link 55 and the antenna 54 . The received packets are then forwarded to the packet processor 51 , which can use conventional techniques to disassemble the packets and recover the communication information therefrom. The communication information can then be forwarded to the communications application 52 . The above-described cooperation between the packet processor 51 , the communications application 52 and the wireless communications interface 53 for permitting wireless communication of packets to and from slave devices is well known in the art.
According to the present invention, a retransmission controller 56 is coupled to the packet processor 51 for implementing dynamic retransmission slot assignment according to the invention. The retransmission controller 56 has an input 57 for receiving conventionally available information indicative of any change in the number of users, for example, any change in the number of slave devices currently active in the piconet. This information is conventionally maintained in the master device. In response to a change in the number of users, the retransmission controller 56 updates an internal pointer which points to the point in time where the transmission period ends and the retransmission period begins. Examples of the pointer are illustrated in FIGS. 4 and 5 above. Each time the retransmission controller updates the pointer in response to a change in the number of users, the retransmission controller at 58 outputs the pointer value to the packet processor 51 . From this pointer value, the packet processor 51 knows when the transmission period ends and the retransmission period begins.
The packet processor 51 can use conventional techniques to send and receive all packets during the transmission period, and can also use conventional techniques to produce any master-to-slave (MS) packets which, in view of the packets received (or not received) from the slave devices during the transmission period, need to be transmitted to the slave devices during the retransmission period. For example, during the transmission period in FIG. 6 , slave S 1 and slave S 3 have transmitted a NAK to the master, and the CRC (cyclic redundancy code) checksum value in the packet transmitted to the master by slave S 2 does not check correctly. Accordingly, the packet processor 51 would, in response to this transmission activity, conventionally prepare a retransmission packet for transmission from the master to slave S 1 , a NAK packet for transmission from the master to slave S 2 , and a retransmission packet for transmission from the master to slave S 3 . However, instead of transmitting these packets to the slave devices in conventional fashion, the packet processor 51 instead outputs these master-to-slave (MS) packets to an input 59 of the retransmission controller 56 . The retransmission controller 56 then assigns these master-to-slave packets to the available slots in the retransmission period as desired, and outputs at 60 a modified master-to-slave packet flow reflecting the retransmission time slot assignments, for example the master-to-slave packet flow illustrated in the retransmission period of FIG. 6 .
The retransmission controller uses a control signal 61 to control a selector 62 such that the modified master-to-slave packet flow at 60 is provided to the wireless communications interface 53 during the retransmission period. The control signal 61 controls selector 62 such that the output 60 of the retransmission controller 56 is coupled to the wireless interface 53 during the retransmission period. However, during the transmission period, the control signal 61 controls selector 62 such that the output 63 of the packet processor 51 is coupled to the wireless communications interface 53 for normal transmission of packets to the slave devices.
The master-to-slave packet flows illustrated in the retransmission periods of FIGS. 7 and 8 are further examples of the modified master-to-slave packet flow output at 60 by the retransmission controller 56 of FIG. 9 . Comparing the example of FIG. 6 with the example of FIG. 8 , the retransmission controller 56 can choose to utilize a conventional NAK packet for sending a NAK to slave S 2 as shown in FIG. 6 , or the retransmission controller 56 can choose to include the NAK for slave S 2 in its retransmission to slave S 1 , as illustrated in FIG. 8 . It should also be noted that the modified master-to-slave packet flow output at 60 by retransmission controller 56 can, when the number of users has changed, include a suitable broadcast packet directing each active slave in the piconet to update its record of the pointer illustrated in FIGS. 4 and 5 . For example, the pointer value can be sent to the slaves in a message within a Bluetooth broadcast packet.
FIG. 10 illustrates exemplary operations which can be performed by the master device of FIG. 9 . At 101 and 102 , the master device exchanges packets with the slave devices of the piconet during the transmission period. After the transmission period ends (known from the pointer value) at 102 , it is determined at 103 whether the number of active slave devices in the piconet has changed. If so, the pointer of FIGS. 4 and 5 is updated at 104 , and a retransmission slot is assigned at 105 to broadcast the pointer to the slaves of the piconet. After assigning a retransmission slot for broadcasting the pointer at 105 , or if the number of slaves has not changed at 103 , the available retransmission slots are assigned for the desired packets at 106 , for example the packets illustrated in the retransmission slots of FIGS. 6–8 . Thereafter at 107 , a packet is transmitted according to the slot assignment. If the packet transmitted at 107 includes a NAK at 108 , then the corresponding retransmission is received at 110 . Thereafter, or if the packet transmitted at 107 does not include a NAK at 108 , it is determined at 109 whether or not the retransmission period has ended. If not, the next master-to-slave packet is transmitted at 107 . On the other hand, if it is determined at 109 that the retransmission period has ended, for example, either by a time-out condition or by successful retransmission of all desired packets, then operations return to 101 for the exchange of packets with slave devices during the next transmission period. All master-to-slave packets can be considered to be successfully retransmitted when the master has received the expected ACK from the associated slave. All slave-to-master packets can be considered to be successfully retransmitted when the CRC code of the packet checks correctly at the master.
FIG. 11 diagrammatically illustrates pertinent portions of exemplary embodiments of the slave devices (e.g., mobile units in a cordless phone system) illustrated in FIGS. 2–8 . The slave device of FIG. 11 includes a packet processor 111 coupled for bidirectional communications with a communications application 112 and a wireless communications interface 113 . These components can cooperate in generally the same conventional fashion described above with respect to the packet processor 51 , communications application 52 and wireless communications interface 53 of FIG. 9 in order to permit bidirectional wireless packet communications between the slave device of FIG. 11 and the master device of FIG. 9 via antenna 114 and wireless communications link 115 , for example a Bluetooth radio link. According to the invention, a MAC (media access control) processor 116 is coupled to the packet processor to receive therefrom the slave address information and the TYPE bits included in the packets received by the packet processor 111 . The MAC processor 116 can determine from the address information whether or not the received packet is addressed to the slave device of FIG. 11 . If so, the MAC processor determines whether the received packet is a retransmission from the master device and whether it includes a NAK indication from the master device. If the packet is determined to be a retransmission packet, then at 117 the MAC processor signals the packet processor 111 to process the retransmission packet in conventional fashion. Furthermore, if the MAC processor determines that the received packet includes a NAK indication to the slave device of FIG. 11 , then at 118 the MAC processor 116 signals the packet processor 111 to retransmit the packet that was earlier transmitted to the master device during the transmission period.
If the address information indicates that the received packet is not addressed to the slave device of FIG. 11 , the MAC processor 116 nevertheless inspects the TYPE bits of the received packet. If these bits indicate that the master device has sent a NAK to the device of FIG. 11 in a packet addressed to another slave device, then at 118 the MAC processor 116 instructs the packet processor 111 to retransmit the packet that was earlier transmitted during the transmission period.
Note also that the MAC processor receives an enable signal from the packet processor 111 so that the MAC processor 116 can be enabled for operation only during the retransmission period. The enable signal output by the packet processor 111 is driven in response to the pointer information extracted by the packet processor 111 from the aforementioned broadcast packet transmitted by the master. Thus, when the packet processor 111 determines from its current pointer information that the transmission period has ended, the packet processor 111 drives the enable signal active to enable the MAC processor 116 for operation during the retransmission period. After the retransmission period expires, the enable signal is used to disable MAC processor 116 .
FIG. 12 illustrates exemplary operations which can be performed by the slave device of FIG. 11 . As illustrated at 121 and 122 , the slave device exchanges packets with the master device, and then awaits the end of the transmission period (known from the pointer value). After the transmission period has ended at 122 , the slave device receives a packet at 123 , and thereafter determines at 124 whether or not the packet is a broadcast packet regarding a new pointer value. If so, the pointer value is updated at 125 . If the received packet is not a broadcast packet regarding the new pointer value at 124 , then it is determined at 126 whether or not the received packet is addressed to the slave device. If so, the received packet can be processed conventionally at 129 . It is then determined at 128 whether or not the received packet includes a NAK indication. If so, a retransmission is performed at 130 .
If it is determined at 126 that the received packet does not address the slave device, it is thereafter determined at 128 (e.g., from the TYPE bits) whether or not the received packet nevertheless includes a NAK for the slave device. If so, a retransmission is performed at 130 . After retransmitting at 130 , or after determining that no NAK has been received at 128 , or after updating the pointer at 125 , it is determined at 131 whether or not the retransmission period has ended. If not, then the above-described operations at 123 – 130 are repeated until it is determined at 131 that the retransmission period has ended, whereupon the slave device exchanges packets with the master at 121 in the next transmission period.
FIG. 13 diagrammatically illustrates pertinent portions of a further exemplary embodiment of the master device of FIG. 9 . In the embodiment of FIG. 13 , the communications application 52 (see also FIG. 9 ) includes a conventional 32 kilobit/second ADPCM speech coder. This permits up to 4 users with 2 retransmissions. The wireless communications interface 53 of FIG. 13 (see also FIG. 9 ) includes a conventional switched antenna diversity section which controls wireless communications over the wireless communications link 55 via a plurality of antennas. The exemplary embodiment of FIG. 13 can otherwise be the same as FIG. 9 .
FIG. 13A illustrates an embodiment generally similar to FIG. 13 , but including a conventional GSM EFR speech coder.
FIG. 14 diagrammatically illustrates pertinent portions of a further exemplary embodiment of the slave device of FIG. 11 . In the embodiment of FIG. 14 , the communications application 112 (see also FIG. 11 ) includes a conventional 32 kilobits/second ADPCM speech coder. The wireless communications interface 113 of FIG. 14 (see also FIG. 11 ) includes a conventional switched antenna diversity section which controls wireless communications over the wireless communications link 115 via a plurality of antennas. The exemplary embodiment of FIG. 14 can otherwise be the same as FIG. 11 .
FIG. 14A illustrates an embodiment generally similar to FIG. 14 , but including a conventional GSM EFR speech coder.
FIG. 15 illustrates exemplary simulation results 151 associated with the embodiments of FIGS. 13 and 14 (32 kbps APDCM speech coding), as compared to the embodiments of FIGS. 13A and 14A (GSM EFR speech coding) with (152) and without (153) transmission diversity.
It will be evident to workers in the art that the above-described embodiments of FIGS. 2–14A can be readily implemented, for example, by suitable modifications in software, hardware, or a combination of software and hardware, in conventional wireless communication devices such as Bluetooth masters and slaves.
Although exemplary embodiments of the invention are described above in detail, this does not limit the scope of the invention, which can be practiced in a variety of embodiments.
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In wireless communication arrangements that utilize a transmission period of time followed by a retransmission period of time, the utilization and effectiveness of retransmission communications can be advantageously increased by dynamically assigning desired communications to respective retransmission time slots of the retransmission period.
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CROSS-REFERENCE TO PREVIOUS RELATED APPLICATION
[0001] This invention claims priority from U.S. Provisional Patent Application Ser. No. 60/609,415, filed on Sep. 13, 2004, the complete disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to chairs in general, and more particularly to recliner chairs and lift chairs, and more particularly still to a recliner or lift chair wherein the back frame is movable independent of the seat frame and footrest, and can be positioned in both a zero gravity and Trendelenburg position.
[0004] 2. Preliminary Discussion
[0005] Recliner chairs and lift chairs have been on the market for years, with the utility of recliners being primarily for use in living rooms and family rooms, while lift chairs are used by the handicapped, elderly, or disabled to assist them in moving from a reclined or sitting position to a standing position. While a substantial number of today's recliners are still manually operated, a growing number of recliners, and almost all lift chairs, utilize one or more actuators to move the footrest, back frame, and seat frame into various positions with respect to each other including reclining positions within a specified range, as well as to physically lift the chair while tipping it forward to aid the occupant to stand up. In one known chair type, independent movement of the footrest and backrest is accomplished through the use of separate actuators, while other chairs utilize a single interconnected actuator to cause the footrest and backrest to move together or simultaneously. In the past, in those recliner chairs in which the back frame is movable independent of the position of the seat frame or footrest, the back frame actuator has been connected between the back frame and either the chair frame or lift frame. Unfortunately, the range in which the back frame can be pivoted or moved without being impeded or obstructed by other parts or components of the chair, such as the chair frame, lift frame actuator, or seat frame, is rather limited, depending upon the particular lift or recline position the chair is in. In other words, despite the use of a separate chair back actuator, the position of the back frame is still limited.
[0006] In addition to the usual television watching and other relaxing positions, a few known chairs can also be moved or pivoted into certain special positions. One of these is the so-called Trendelenburg position, wherein the occupant's legs are situated so that they are higher in relation to the ground than the heart. This position is useful particularly for those having certain circulatory, kidney, or other ailments, since in such position gravity assists the flow of blood from the legs back to the heart. Another special position is the so-called “zero gravity” or 90/90 position. To achieve such position, the chair is moved so that the head and torso are at a slight upward angle, the legs up to the knee are bent at a similar opposite upward angle, and the knees are bent so that the lower area of the legs is angled similarly to the torso. The zero-gravity position approximates the position or posture that astronauts assume when sleeping in a weightless environment. The primary benefit of such position is reduced pressure on the spine, which often relieves back pain at least to some extent. Other benefits include reduced heart stress, relief of tension in the body, and improved circulation. So far as the inventors are aware, no prior art motor actuated lifts chairs or recliners can achieve both the Trendelenburg and zero-gravity positions as well as independent movement of the back frame relative to the seat frame and footrest.
[0007] It has now been discovered that by securing the actuator for moving the back frame independently of the lift frame and footrest between the back frame and the seat frame in such a manner that such actuator can move along with or relative to the seat, and by providing a unique linkage mechanism, when the actuator for moving the footrest is utilized, the seat frame can also be simultaneously moved to any position the recliner mechanism is capable of providing without interfering or coming into contact with the actuator for moving the back frame or any other parts of the chair. Thus, in one embodiment, as the footrest is moved upwardly, the back frame will move rearwardly at the same time until the footrest is in a substantially horizontal position. Then, if one tries to move the footrest beyond such substantially horizontal position, the footrest as well as the back frame will both move together in a generally upward direction. At the same time, the back frame can be moved independently of the footrest and seat frame using its own actuator. If such an arrangement is provided on a combination recliner and lift chair, the actuator for the footrest and seat frame will be moved to a closed position and then continue beyond such position until the frame of the chair is lifted upwardly and tilted forwardly by the lift assembly. By arranging the actuators in such a manner, the chair can provide multiple positioning of the occupants or user ranging from the Trendelenburg position to various recline and lift positions. Such arrangement also enables the footrest, back frame, and seat to move together if desired, while moving the footrest and seat together, with the seat moving rearwardly, allows the seat be articulated up at an angle which is comfortable and puts the occupant in a so-called “zero gravity” or back relief position, which provides complete support for the occupant and takes pressure off the spine. A size-adjustable stop is also used to alter slightly the final angle of the footrest in relation to the seat frame.
[0008] 3. Description of Related Art
[0009] The prior art evidences multiple chairs consisting of known and expected structural configurations designed to move between a reclined position, a sitting position, and a lift position wherein the occupant is enabled more easily to assume a standing or upright position, as well as a wide range of alternative designs that have been developed to fulfill countless specific objectives and requirements. The following patent documents are illustrative of the present state of this field.
[0010] U.S. pat. No. 3,016,264 issued to A. L. Hughes on Jan. 9, 1962, entitled “Motor-Operated Reclining Chair”, discloses a recliner wherein the backrest ( 22 ) is pivotally mounted to the side arms of the chair, and is movable by a drive mechanism ( 72 ). However, the drive mechanism is connected between the chair frame and a pair of arm members that comprise part of the main support structure of the chair, rather than between the chair and seat frames, and therefore suffers from the disadvantage of having a limited range of motion.
[0011] U.S. Pat. No. 3,743,348 issued to C. J. Sloan on Jul. 3, 1973, entitled “Reclining Chair and Mechanism Therefore”, discloses a recliner assembly wherein in one embodiment, illustrated in FIG. 8 , dual motors are provided, with motor 120 being used to pivot the back frame, while motor 126 is used to deploy the footrest. Back frame motor 120 , however, appears to be connected between the chair plate and back plate, so that while the position of the back is movable independently of the position of the legrest, it is not movable independently of the position of the seat frame in the same manner as the present invention, which as a result can achieve a wider range of reclining positions.
[0012] U.S. Pat. No. 4,007,960 issued to E. J. Gaffney et al. on Feb. 15, 1977, entitled “Reclining Elevator Chair”, discloses a lift-recliner chair in which while movable to a substantially fully reclined position, the back frame appears to be movable with respect to the seat only when the entire chair is being moved to a reclined position, rather than moved independently of the position of the seat frame and footrest.
[0013] U.S. Pat. No. 4,365,836 issued to W. R. Jackson et al. on Dec. 28, 1982, entitled “Motorized Reclining Chair”, discloses a recliner chair having a single motor or actuator. While the linkage system for such chair enables it to be moved to a conventional television viewing position and a resting position, there is no means for changing the position of the backrest independently of the position of the seat frame or footrest.
[0014] U.S. Pat. No. 4,386,803 issued to C. W. Gilderbloom on Jun. 7, 1983, entitled “Motorized Reclining Chair”, discloses a recliner wherein the chair back, seat, and leg rest are claimed to be independently adjustable, and in addition an adjustable head supporting means is provided. As shown in FIG. 1 , while such chair appears to be capable of attaining a wider than usual range of reclining positions the arrangement of the motors and linkage mechanism are unlike the simplified arrangement of the present invention.
[0015] U.S. Pat. No. 4,852,939 issued to B. J. Krauska on Aug. 1, 1989, entitled “Device for Converting a Recliner Chair to a Recliner-Lift Chair”, discloses a base that when connected to a conventional recliner turns it into a power actuated recliner and lift chair. The back frame, however, is not independently movable, and therefore the number of reclining positions that can be achieved with such chair are substantially limited.
[0016] U.S. Pat. No. 5,013,084 issued to T. J. May on May 7, 1991, entitled “Mechanism for High-Leg Reclining Apparatus”, discloses a dual legrest type recliner chair capable of attaining an upright, TV, and fully reclined position. The linkage of the chair back frame to the seat frame does not allow for independent movement of the chair back, however.
[0017] U.S. Pat. No. 5,165,753 issued to E. D. Henderson on Nov. 24, 1992, entitled “Elevator Chair Apparatus” discloses a lift chair wherein the sub-frame pivots on a base portion having a rearwardly inclined upper surface. In a lift position, the sub-frame pivots on the front edge of the inclined surface via an actuator. U.S. Pat. No. 5,520,439 issued to E. D. Blount on May 28, 1996 entitled “Fully Reclinable Elevator Lift Chair”, discloses a lift-recliner chair that is an improvement on the Henderson '753 chair in that it can also be moved to a fully reclined position, while the Henderson chair cannot. The actuator in Blount is connected between the base and a pivotable transverse bar on which the back is supported by brackets, so that when the motor ram is moved away from the motor, eventually the bar pivots to cause the back to recline. See also commonly owned continuation-in-part U.S. Pat. No. 5,806,920 entitled “Fully Reclinable Elevator Lift Chair with Ottoman” wherein an elevatable footrest is also provided. None of such arrangements appears to allow for completely independent adjustment of the back frame, however.
[0018] U.S. Pat. No. 5,265,935 issued to G. Geisler et al. on Nov. 30, 1993, entitled “Stand-Assist Recliner Chair”, discloses a lift-recliner wherein the actuator is secured between two separate crank arms under the chair seat. The linkage mechanism used, however, does not appear to provide the same maneuverability of the back section recliner as is possible with the present inventors' arrangement.
[0019] U.S. Pat. No. 5,312,153 issued to J. Lin on May 17, 1994, entitled “Recline Lift Wall Hugger Chair”, discloses an arrangement for enabling a chair to pivot forwardly, or away, from a wall when it is to be moved into a reclining position. In the embodiment shown in FIGS. 12-14 , the backrest is tiltable relative to the seat using a crank arm connection arrangement between the backrest and seat. However, the seat still must move forwardly for the back to move to a fully reclined position, and there is no means for independently pivoting the backrest with respect to the seat portion.
[0020] U.S. Pat. No. 5,354,116 issued to T. J. May et al. on Oct. 11, 1994, entitled “Reclining Chair with Articulating Linkage for Padded Intermediate Ottoman”, discloses a recliner having a linkage mechanism connecting the legrest, seat, and backrest. The linkage system does not provided for independent movement of the backrest, however.
[0021] U.S. Pat. No. 5,498,055 issued to P. R. Goldman on Mar. 12, 1996, entitled “Recliner: Apparatus and Method”, discloses a recliner wherein the user's feet are elevated above his or her heart in a fully reclined position. As shown in FIG. 2 , the entire chair can pivot about an axis ( 21 ) in relation to the chair frame ( 13 ), while the seat and back as well as the seat and footrest are also independently pivotable with respect to one another, so that numerous reclined positions are possible, one of which is to have the footrest raised upwardly so that the user's feet are above his or her heart. A means for automatically moving the footrest when the backrest is rotated is also provided. While the Goldman recliner therefore can be moved into a Trendelenburg position, this is accomplished in a completely unique manner unlike the present invention, and it is unclear whether a bed-like position can be reached.
[0022] U.S. Pat. No. 5,582,457 issued to K. J. Komorowski et al. on Dec. 10, 1996, entitled “Dual Leg Rest Assembly”, discloses a linkage assembly for a legrest wherein coordinated movement of first and second leg rest panels, i.e., a dual legrest, is provided. A separate linkage means for tilting the backrest is also shown, but the back frame is not movable via a power actuator means.
[0023] U.S. Pat. No 5,651,580 issued to L. P. LaPointe et al. on Jul. 29, 1997, entitled “Linear Actuation Drive Mechanism for Power-Assisted Chairs and Base Therefor”, discloses a lift-recliner chair that utilizes a single linear action drive mechanism to selectively actuate the reclining linkage assembly, footrest linkage assembly, and the lift and tilt assembly. Such chair, which is the subject of several related patents, does not appear to disclose a motor actuated system for independently adjusting the position of the backrest.
[0024] U.S. Pat. No. 6,000,758 issued to W. E. Schaffner et al. on Dec. 14, 1999, entitled “Reclining Lift Chair”, discloses a chair having a novel linkage mechanism system for lifting and reclining in which when a bell crank is pivoted in a clockwise direction by an actuator, the chair back is caused to recline, and in addition having an environmental control system. There does not appear to be a means for independently adjusting the position of the chair back with respect to the chair seat frame in any of the disclosed embodiments, however, so that the range of positions in which the chair can be reclined is limited in comparison to the present invention.
[0025] U.S. Pat. No. 6,022,076 issued to I. Samson on Feb. 8, 2000, entitled “Reclinable Seating”, discloses a recliner chair in which the center of gravity of the reclining unit remains in a horizontal plane as it moves between an upright and reclined position, thereby increasing the stability of such chair in these positions. While the Samson recliner appears to possibly be movable to a zero-gravity position, such chair does not disclose any of the unique features of the present invention.
[0026] U.S. Pat. No. 6,135,559 issued to J. R. Kowalski on Oct. 24, 2000, entitled “Seat Back Reclining Mechanism Adaptable to Chairs with Stationary or Movable Seats”, discloses a recliner that includes a linkage mechanism for pivoting the seat back independent of and without regard to the position of the seat. However, movement of the back is initiated by manual force against the chair back and against the force of a coil spring, rather than utilizing a power actuator to move the seat, and the number of reclined positions is limited in comparison to the present invention.
[0027] U.S. Pat. No. 6,142,558 issued to T. J. May on Nov. 7, 2000, entitled “Recliner with Primary and Secondary Ottomans”, discloses a “low leg” recliner chair having a unitary linkage arrangement for the chair legrest, seat, and back. The May chair is not motor actuated, however, and the backrest appears to pivot in unison with the seat, rather than completely independent of the seat movements as in the present invention.
[0028] U.S. Pat. No. 6,213,554 issued to Y. Marcoux et al. on Apr. 10, 2001, entitled “Lift Chair”, discloses a lift chair mechanism for a lift chair having a chair frame that can be reclined independently of the lift mechanism and base frame, as well as providing for a rocking motion. The chair back cannot be reclined independent of the seat frame, however.
[0029] U.S. Pat. No. 6,840,575 issued D. Hesse on Jan. 11, 2005, entitled “Seat-Recliner Fitting That Can be Adjusted by a Motor”, discloses a fitting for adjusting the inclination of a seat back and a footrest of a recliner using separate actuators. While such arrangement appears to enable the backrest to be moved independently of the position of the seat portion, the specification nevertheless indicates that the seat is moved forward at the same time the back is moved. In addition, the linkage mechanism on which the seat is pivoted is unlike that of the present lift-recliner chair, and the use of an adjustable size spacer for microadjustment of the angle of the footrest in a fully reclined position is also not disclosed.
[0030] German Gebrauchmuster Patent Application DE 9420149.8 filed by W. Hoormann et al. on Dec. 16, 1994, discloses according to in FIGS. 1 and 2 , a recliner having a pair of actuators or motors, one of which is connected to the backrest. However, such motor appears to 5 be connected on its other end to the chair frame rather than the seat, and therefore would not provide the same advantages available in the present disclosure.
[0031] U.K. Patent Application 2,030,854 published on Apr. 16, 1980, entitled “Reclining Chair”, discloses a recliner wherein the seat and back are pivotally connected to the base as well 20 as to each other. When the back pivots, the seat also must pivot, so that there does not appear to be a means for pivoting the seat independently of the back.
[0032] U.K. Patent Application No. 2,407,493 published on Apr. 5, 2005 entitled “Powered Lift Reclining Chair”, discloses a lift-recliner chair having an actuator for pivoting the back portion with respect to the seat portion, as well as the seat portion with respect to the base portion. The actuators are substantially enclosed within the base portion of the chair at all positions of the chair, which arrangement reduces the risk of entrapment and injury during movement of the chair (as shown in FIGS. 2 and 3 ). It is indicated that the actuator for moving the back portion is “fixed” relative to the seat portion. As shown in FIG. 2 , however, actuator ( 66 ) is mounted to base frame cross member ( 26 ) on one end and the actuator arm ( 67 ) is mounted to cross member ( 60 ), not the seat frame.
[0033] While the aforementioned prior art devices fulfill their respective, particular objectives and requirements, they do not disclose a lift or recliner chair having the particular capabilities and advantages of the present invention. The chair according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides a lift and recliner chair having an independently operating back and a movement rearwardly and upwardly of the seat to a substantially reclining position as the footrest is activated, that is capable of easily achieving a wider range of reclining positions, including both a Trendelenburg and zero-gravity position.
OBJECTS OF THE INVENTION
[0034] It is therefore a primary object of the invention to provide a combination lift chair and reclining chair in which the chair progresses from a sitting position to either a lift position on the one hand or a Trendelenburg position on the other hand.
[0035] It is a still further object of the invention to provide a combination lift chair and Trendelenburg chair.
[0036] It is a still further object of the invention to provide a combination reclining and lift chair in which the seat lifts in combination with the footrest to provide a raised position that can be varied with various positions of the back to provide multiple resting positions.
[0037] It is a still further object of the invention to provide a reclining chair with a larger variety of positions than have been previously available.
[0038] It is a still further object of the invention to provide a lift chair with a novel mechanical arrangement for providing a variety of positions for the occupant.
[0039] Is a still further object of the invention to provide a lift chair with a superior linkage system and arrangement providing a plurality of resting positions for the occupant as well as a position aiding the occupant to arise from the chair.
[0040] It is a still further object of the invention to provide a lift chair which is enabled to have an independently operating back in which the operating motor for the back is anchored to the seat rather than to the frame of the chair or to the lift assembly.
[0041] It is a still further object of the invention to provide a lift and reclining chair that can achieve both a Trendelenburg reclined position and a zero-gravity reclined position.
[0042] It is a still further object of the invention to provide a spacer means for adjusting slightly the angle of the footrest in a fully reclined position.
[0043] It is a still further object of the invention to provide a lift and reclining chair having a independently positionable back frame having a linkage mechanism that is strong and durable and stable enough to withstand repeated use over time.
[0044] Still other objects and advantages of the invention will become clear upon review of the following detailed description in conjunction with the appended drawings.
SUMMARY OF THE INVENTION
[0045] A novel mechanical arrangement for use with recliner chair or lift chair is provided involving two independently operating actuators or motors secured to the parts of the chair in a novel manner such as to allow a substantial reclining or sitting position in a central position, a Trendelenburg or legs elevated with respect to the heart elevation position on one side of a reclining or sitting position, and a lift position for allowing or aiding the occupant to stand up and leave the chair on the other side or position. By pivotably connecting the operating actuator for the back between the seat frame and back frame, such operating actuator will move as the seat frame is moved and stay in the same general relative position with respect to the seat frame at all times. In addition, a linkage arrangement for accomplishing such independent pivotable movement is also provided, as well as a means for slightly adjusting the angle of the footrest in a fully reclined position, whereby the chair occupant may also adjust the chair to a zero-gravity reclining position. Such mechanical arrangement can be used with any recliner and/or lift mechanism or arrangement and results in an overall more comfortable and versatile recliner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 is a front perspective view of the chair of the invention in a fully reclined position with most of the frame including one of the arm frames and the upholstery removed.
[0047] FIG. 2 is an isometric view of the lift frame or assembly of the chair in a retracted position.
[0048] FIG. 3 is an isometric view of the lift frame or assembly of the chair in an extended position.
[0049] FIG. 4 is an isometric view of the C-shaped bar for pivotably connecting the seat frame and the recliner motor or actuator assembly.
[0050] FIG. 5 is an isometric view of the recliner mechanism of the chair in a retracted position.
[0051] FIG. 6 is an isometric view of the recliner mechanism of the chair in an extended position.
[0052] FIG. 7 is an isometric view from the left front showing the seat frame and back frame portions of the chair of the invention with the seat back motor or actuator connected and with the back frame in an upright position.
[0053] FIG. 8 is an isometric view from the right rear showing the seat frame and back frame portions of the chair of the invention with the seat back motor or actuator connected and with the back frame in an upright position as shown in FIG. 7 .
[0054] FIG. 9 is an isometric view from the left front showing the seat frame and back frame portions of the chair of the invention with the seat back motor or actuator connected and with the back frame in an reclined position.
[0055] FIG. 10 is a side view showing the seat frame and back frame portions of the chair of the invention with the seat back motor or actuator connected and with the back frame in an reclined position.
[0056] FIG. 11 is an isometric view of the bar for pivotably connecting the chair back motor or actuator assembly to the seat frame.
[0057] FIG. 12 is an isometric view of the back frame attaching bar for pivotably connecting the seat back motor or actuator to the seat back.
[0058] FIG. 13 is a side view showing the chair frame portion of the invention with the seat frame having an alternative preferred attachment assembly, footrest, and back frame portions of the chair of the invention in a reclined position, the seat back motor or actuator and recliner motor or actuator connected, and the recliner mechanism connected.
[0059] FIG. 14 is a right side perspective view of the chair frame portion of the invention similar to FIG. 13 with the seat frame, footrest, and back frame portions of the chair of the invention in a reclined position, the seat back motor or actuator and recliner motor or actuator connected, and the recliner mechanism connected.
[0060] FIG. 15 is a left front perspective view of the chair of the invention in an upright or normal starting position showing the lift frame and recliner mechanism, with the chair arm frames and upholstery removed.
[0061] FIG. 16 is a rear perspective view of the chair of the invention in an upright or normal starting position showing the lift frame and recliner mechanism, with the chair arm frames and upholstery removed.
[0062] FIG. 17 is a side view of the chair of the invention in an upright or normal rest position showing the lift frame and recliner mechanism, with the arm frames and upholstery removed.
[0063] FIG. 18 is a right rear perspective view of the chair of the invention in a fully reclined position with the arm frames and the upholstery removed.
[0064] FIG. 19 is a side view of the chair of the invention in a fully reclined position with the arm frames and the upholstery removed.
[0065] FIG. 20 is a right rear perspective view of the chair of the invention with the seat and footrest in a reclined position, but with the back frame in an upright position, with the arm frames and upholstery removed.
[0066] FIG. 21 is a side view or elevation of the chair of the invention with the seat and footrest in a reclined position, but with the back frame in an upright position, with the arm frames and upholstery removed.
[0067] FIG. 22 . is a rear view of the chair of the invention having the arm frames and upholstery thereon with the lift mechanism in a raised position.
[0068] FIG. 23 is a left rear perspective view of the chair of the invention with the lift mechanism in a raised position.
[0069] FIG. 24 is a plan view of a hand operated button type electrical controller for operation of the chair of the invention.
[0070] FIG. 25 is a front perspective view of anther alternative embodiment of the chair of the invention.
[0071] FIG. 26 is a side view of the chair shown in FIG. 25 in a zero-gravity position.
[0072] FIG. 27 is a partial front view of the back frame linkage mechanism of the chair shown in FIG. 25 .
[0073] FIG. 28 is a partial rear view of the back frame linkage mechanism of the chair shown in FIGS. 25-27 .
[0074] FIG. 29 is a partial rear view similar to FIG. 28 with the chair back frame removed and showing the stop means for adjusting the angle of the footrest slightly.
[0075] FIG. 30 is a perspective view of the improved alternative back frame linkage mechanism of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0076] The following detailed description is of the best mode or modes of the invention presently contemplated. Such description is not intended to be understood in a limiting sense, but to be an example of the invention presented solely for illustration thereof, and by reference to which in connection with the following description and the accompanying drawings one skilled in the art may be advised of the advantages and construction of the invention.
[0077] FIGS. 1-12 and 15 - 24 illustrate a first embodiment of the present invention, FIGS. 13-14 illustrate a second embodiment wherein a preferred chair backframe pivot mechanism is disclosed, and FIGS. 25-28 illustrate another preferred embodiment of such chair backframe pivot mechanism. Referring first to FIG. 1 , there is shown a perspective view of chair 20 of the invention in a reclined position, with the right arm frame, from the point of view of a chair occupant, and all of the upholstery removed to illustrate the components of the invention underneath. Chair 20 is comprised of a lift frame or assembly 22 , shown in greater detail in FIGS. 2-3 , and chair assembly 23 which is attached to lift frame or assembly 22 . Chair assembly 23 generally includes seat frame 24 , back frame 26 , leg or footrest 27 , pair of arm frames 28 , only one which is shown in FIG. 1 , and linkage mechanisms 104 . It will be understood that arm frames 28 of chair assembly 23 , which arm frames are usually of a wooden construction and are overall conventional, and one possible embodiment of the wooden chair frame attached to lift frame 22 is shown in FIGS. 22 and 23 . As shown in FIGS. 2-3 , lift frame 22 includes base frame 32 , which is comprised of a rear crossbar 34 , spaced apart parallel bars 35 and 36 connected to and extending forwardly from rear crossbar 34 , and brace 37 spaced apart from rear crossbar 34 and connecting between bars 35 and 36 . Forward ends 38 and 39 of parallel bars 35 and 36 curve outwardly towards the perimeter of the chair, essentially matching the ends of crossbar 34 so that base frame 32 forms a stable base or floor support for chair assembly 23 when it is in a raised or lift position, a normal seated position, or when it is in any number of reclined positions. Foot members (not shown) adjustable or unadjustable and usually padded in some manner may also be attached to the underside of rear crossbar 34 and on the forward ends 38 and 39 of parallel bars 35 and 36 , or at any other desired location. Also connected to parallel bars 35 and 36 near rear crossbar 34 are large brackets 42 and 43 , respectively, each having apertures 44 , 45 , and 46 therein to facilitate pivotable attachment to the ends of U-shaped bar member 48 and straight bars 50 - 51 . The ends of U-shaped bar 48 are pivotably connected by pins or pintles 47 extending though apertures 44 in brackets 42 and 43 and corresponding aligned apertures in U-shaped bar 48 . Further, straight bar 50 is connected to bracket 42 by a pin or pintle extending through aperture 46 and matching apertures in bar 50 , while identical straight bar 51 is connected by a pin or pintle extending through aperture 46 in bracket 43 and matching apertures in bar 51 . If it is desired to change the angle of the lift position of the chair slightly, bars 50 and 51 could be secured in apertures 45 rather than apertures 46 . Identical short links 54 and 56 (not shown) pivotably connect the upper ends of bars 50 and 51 to U-shaped bar 48 via pins or pintles 57 and 58 extending through apertures in such bars 48 and 50 - 51 , respectively. Such double bar structure gives lift assembly 22 added strength and integrity so that it is sufficiently strong to support the maximum weight of the chair frame plus an occupant of the chair over an extended period of use.
[0078] Also pivotably connected to bars 48 and 50 - 51 on the side opposite links 54 and 56 via pins 57 and 58 , respectively, is chair frame support structure 60 . Chair frame support structure 60 is comprised of similar outwardly facing C-shaped bar sections 62 and 63 which are connected together by welding to third downwardly facing C-shaped section 64 situated at a right angle to sections 62 and 63 . In addition, square bar sections or braces 65 are secured by welding adjacent the connection points of bar sections 62 and 63 and C-shaped section 64 through which the apertures for receiving pins 57 are provided, and serve as strengthening members for support structure 60 . The ends of C-shaped bar sections 62 and 63 are secured to the underside of bottom pieces 110 of the arm frames 28 (shown in FIGS. 22 and 23 ) of the chair frame via screws or the like extending through apertures 66 and 67 in such bars sections. Rear crossbar 34 , bars 35 and 36 , brace 37 , C-shaped bar 48 , straight bars 50 and 51 , C-shaped sections 62 , 63 , and 64 of chair frame support structure 60 , and brace 65 are all preferably made of hollow rectangular steel bars that are welded together where appropriate. The pins or pintles, as well as brackets 42 and 43 , and brackets 72 and 80 (discussed below) are also preferably made of steel and welded to the steel bar structures as appropriate.
[0079] Connected spaced from the edges of rear crossbar 34 , and preferably between parallel bars 35 and 36 , is small bracket 72 , to which motor or actuator 74 is pivotably attached by a pin or pintle. Actuator 74 may be any type of actuator including but not limited to electric, gas, and hydraulic actuators. A preferred actuator is an electric motor that relatively rotates an internally threaded sleeve 76 and an externally threaded spindle 75 received therein to increase and decrease their combined overall length, and to thereby adjust the position of objects connected to the end of such threaded sleeve and spindle arrangement. Neither such internal nor exterior threads are visible, but will be understood to be conventional in the art. Suitable actuators are the Omegadrive™ linear actuators commercially available from OkinGmbH & Co. KG located in Gummersbach, Germany, model numbers OS2-SW-394-212 and OZ-SW-330-181. The outer end of externally threaded sleeve 75 is adapted to be pivotably secured to L-shaped bracket or bell crank 78 at a central position by pin or pintle 79 which is passed through matching apertures in the bracket and in the end of sleeve 75 . L-bracket 78 is in turn pivotably connected on its downwardly extending flange to small bracket 80 , which bracket is secured extending downwardly from C-bar section 64 of chair frame support structure 60 by pin or pintle 82 extending through aligned apertures in L-bracket 78 and small bracket 80 . Brackets 72 on crossbar 34 and 80 on chair frame support structure 60 are aligned so that the actuator mechanism extends between such brackets more or less in parallel with bars 50 and 51 .
[0080] Referring again to FIG. 1 , as well as FIG. 7-10 and 13 - 21 , seat frame 24 , back frame 26 , and footrest 27 , all preferably made of wood, are connected to lift frame assembly 22 as follows. Seat frame 24 is comprised of front member 90 , rear member 91 , and side members 92 and 93 , which members are stapled, nailed, or otherwise secured together such as by threaded fasteners or the like to form a rectangular frame or separate frames connected together. The underside of side members 92 and 93 is tapered toward front member 90 at 94 in the present embodiment to allow room for recliner linkage mechanisms 104 , shown detached from chair 20 in FIGS. 5 and 6 . Recliner mechanisms 104 pivotably connects the seat frame 24 , back frame 26 , and footrest 27 together, as described below, as well as to chair frame 28 , resulting in an interconnected whole mechanism. In addition, C-shaped bar 98 , shown attached to seat frame 24 in FIG. 1 and detailed in FIG. 4 , is pivotably connected extending between side members 92 and 93 of seat frame 24 approximately one-third of the way from front member 90 . Bracket 99 is connected by welding to C-shaped bar 98 (see FIG. 4 ) at a position aligned with L-shaped bracket 78 , with apertures 100 therein being aligned with apertures 101 in L-bracket 78 (see FIGS. 2 and 3 ), and pivotably connected thereto by a pin or pintle (not shown) such that expansion lengthening or shortening of actuator 74 is transmitted through bell crank to C shaped bar 98 and hence to the seat structure 24 .
[0081] The details of the recliner linkage mechanisms 104 will now be described with particular reference to FIGS. 5-6 , which illustrate the right side mechanism in a retracted and expanded position, respectively. It will be understood that the recliner mechanism shown in FIGS. 5-6 is designed to be placed on the left side of the chair, or the right side of chair 20 when viewed from the front, and further that the right side or the left side recliner mechanism when viewed from the front is comprised of identical operative parts arranged in mirror image. It will also be understood that the present invention may be used except where specifically indicated with other recliner mechanisms known in the prior art, and the invention is not meant to be limited to use with the described recliner mechanism.
[0082] FIG. 5 illustrates recliner mechanism 104 in a retracted position, while FIG. 6 illustrates recliner mechanism 104 in an expanded position. Before recliner mechanism 104 is attached to chair 20 , however, as shown in FIGS. 22 and 23 , arm frames 28 are operatively secured to lift assembly 22 . More particularly, each arm frame 28 has a bottom side 110 , a front post 112 (shown in FIG. 1 ), a rear post 114 , an arm rest 116 extending between said front and rear posts, and side section 118 which connects between bottom section 110 , front post 112 , and rear post 114 . Each arm frame 28 is secured to one of the C-shaped bar sections 62 and 63 which are part of the lift assembly 22 , so that when the lift assembly is activated, the arm frames along with the rest of chair assembly 23 are lifted upwardly and pivoted or tilted forwardly. More particularly, in the present embodiment, apertures 65 and 66 are provided in C-shaped bar sections 62 and 63 (see FIGS. 2-3 ) through which apertures 65 and 66 screws or other connectors are passed directly into the underside of each arm frame bottom section 110 . Recliner mechanisms 104 are then secured to the side sections 118 of arm frames 28 as described below.
[0083] Referring still to FIGS. 1, 22 and 23 , recliner mechanism 104 includes an elongated arm frame connector plate 120 that is secured preferably by bolts or screws to the inner surface 122 of side section 118 of arm frame 28 through several apertures 105 on the ends and middle section of plate 120 . A spacer block, not shown, may be provided between connector plate 120 and inner surface 122 of arm frame side section 118 to allow for use of slightly different sized frames. In addition, depending on the desired angle of the recliner mechanisms 104 with respect to seat frames 28 , recliner mechanism 104 may be attached to the seat frame 28 at a slight angle. Referring also now to FIGS. 5 and 6 , L-shaped link 130 is pivotably connected at 132 to arm frame connector plate 120 near the rearward end of such plate, and is pivotably connected to angled link 134 at 136 . The end of L-shaped link 130 remote from pivot 136 is facing downwardly in FIG. 5 and is pivotably connected to link 138 at 140 . Meanwhile, link 142 , a portion of which is visible in FIG. 6 behind link 140 , is pivotably and slidably connected to the lower end angled link 134 at 144 in slide 146 in link 134 , while link 142 is further pivotably connected on its other end to arm frame connector plate 120 at 148 (partially visible in FIG. 5 behind link 134 ). Link 138 is pivotably connected to another L-shaped link 150 at 152 , which L-shaped link 150 is also pivotably connected to arm frame connector plate 120 at 154 and pivotably connected to angled link 156 at 158 (visible in FIG. 6 ). Angled link 156 is further pivotably connected to one end of straight link 160 at 162 , and to one end of angled link 164 at 166 . The other end of straight link 160 is pivotably connected to link 182 at 188 , while the other end of angled link 164 is attached to the near end of footrest link 172 at 174 . The far end of footrest link 172 , as well as the far end of footrest link 176 , are both connected to leg 178 of footrest bracket 180 . The near end of footrest link 176 is connected to one end of link 182 at 184 , while link 182 is further pivotably connected to footrest link 172 at 186 , and, as indicated above, to straight link 160 at 188 . Finally, link 182 is also pivotably connected at its rear end to seat frame connector plate 190 at 192 , which plate 190 , as shown FIG. 1 as well as in several of the other Figures, is bolted to the side sections 92 and 93 of seat frame 28 through apertures 194 and 196 . Angled links 134 and 156 are also pivotably connected to seat frame connector plate 190 at 198 and 200 , respectively, while plate 190 is also linked at its upwardly angled rear section 211 directly to L-shaped back frame connector link or bracket 212 .
[0084] In an alternative and preferred link arrangement, shown in FIGS. 13 and 14 , the upwardly bent or angled section 211 of seat frame connector plate 190 is pivotably joined to short link 202 and L-shaped link 212 at 204 , while the opposite end of short link 202 is pivotably joined to 25 straight link 206 at 208 . Straight link 206 is then pivotably joined at its other end to the rearward end of L-shaped link 130 and therefore also to seat frame connector plate 120 at 132 (see FIG. 29 ) Such link arrangement has proven to result in a stronger and more stable connection between back frame 26 , and L-shaped plate 212 and link mechanism 104 . In a further preferred alternative link arrangement, illustrated in FIGS. 25-30 , short link 202 is again, as in the embodiment shown in FIGS. 13 and 14 , pivotably joined to the end of upwardly angled section 211 of seat frame connector plate 190 at 204 , while short link 202 is also again joined at its opposite end to link 206 at 208 . However, in such embodiment, link 204 does not also connect to L-shaped link 212 , but instead, as is best illustrated in FIGS. 27 and 28 , as well as in FIG. 30 , another short link 214 is positioned behind link 202 , which link 214 is pivotably connected to L-shaped link 212 at 215 , and in addition is secured to link 202 at 216 and 217 . In addition, as is visible in FIGS. 25, 27 , 29 , and 30 , a bar 220 is provided connecting between the lower ends of links 214 . The purpose of adding links 214 and bar 220 as described and shown is to add substantially to the overall strength of such linkage arrangement. As can be seen in the FIG. 29 , links 214 are each nonpivotably joined at two points 216 and 217 to links 202 , as well as to each other by bar 220 , and pivotably to links 212 which connect chair back 26 to such linkage system. As a result of such linkage arrangement, a rigid box-like structure or framework is essentially formed around chair back 26 , which structure substantially prevents any bending of any of the links that make up such mechanism from occurring, and therefore substantially increases the overall strength of the chair assembly 23 . In another alternative embodiment, the arrangement shown in FIGS. 13 and 14 may be augmented with the addition of links 214 as shown in FIGS. 25-30 without, however, being connected together by crossbar 220 . Such an intermediate strength mechanism may be suitable in chairs utilizing the linkage independently movable backrest arrangement of the invention wherein the additional strength provided by bar 220 is not required, such as in chairs having a lesser maximum weight limit or carrying capacity. Normally, however, it is believed that the additional strength provided by bar 220 will be most the most preferred structure. In addition, back frame 26 , as shown below, will also be connected to seat frame 24 by the actuator mechanism including second motor or actuator 238 .
[0085] The hollow rectangular bar 244 may have one forward side omitted such that it can fit over the lower section of the backrest directly strengthening such lower section and when connected through fastenings between the plates 246 and 248 with L brackets or fittings 212 forming together with cross bar 220 and essentially rigid rectangular boxed in structure very securely reinforcing the lower end of the backrest plus the rear of the seat frame without massive structural sections on these parts, thus attaining superior strength and operation at only a minor increase in cost or weight while still retaining complete rotational movement of the seat back about a common axis and at the same time keeping the bar 220 completely out of the way with respect to pivoting of the back.
[0086] As indicated above, arm frame connector plate 120 of recliner mechanism 104 is bolted to the inner side surface 122 of side section 118 of arm frame 28 , seat frame connector plate 190 is secured to seat frame 24 , and back frame connector link or bracket 212 is secured to back frame 26 via one of the alternative linkage arrangement just described, thereby joining the seat frame 24 , back frame 26 , and footrest 27 together and forming chair assembly 23 . The arrangement of the links of recliner mechanism 104 further allow the back frame 26 to pivot independent of the footrest 27 and seat frame 26 . In addition, as will now be described with particular reference to in FIGS. 7-12 , which are various perspective views of just the back and seat frame portions of chair 20 , which frame portions may be joined together by the basic linkage arrangement shown in FIGS. 7-10 , the alternative arrangement shown in FIGS. 13-14 , or the second alternative arrangement shown in FIGS. 25-30 , or the intermediate further alternative arrangement described above. In any case, attached generally in the vicinity of C-shaped bar 98 (see FIG. 4 ) extending between first and second side frame members 92 and 93 of seat frame 24 is seat frame motor or actuator attaching bar 230 , which bar is preferably comprised of a hollow rectangular steel bar. Bar 230 is shown in perspective view in FIG. 11 . Welded to the ends of bar 230 are plates 231 and 232 having apertures 234 for securing by bolts, screws, or the like bar 230 to seat frame side members 92 and 93 . In addition, attached extending downwardly from bar 230 , also preferably by welding, is connector 236 having ring-shaped aperture 237 to which seat back motor or actuator 238 is pivotably connected by a pin or the like (see FIGS. 7-10 ). Connector 236 is preferably situated slightly to one side of bar 230 so that motor or actuator 238 can lie or rest side-by-side with motor or actuator 74 described above, which motor is also slightly offset. Seat frame motor or actuator 238 is similar to footrest and lift motor or actuator 74 in that it also typically may be an electric motor that relatively rotates an internally threaded sleeve 240 and an externally threaded spindle 241 received therein to increase and decrease their combined overall length. The opposite end of internally threaded sleeve 240 is pivotably secured to back frame 26 via seat back motor attaching bar 242 . Bar 242 is shown in perspective view in FIG. 12 and is preferably comprised of hollow rectangular steel bar 244 having plates 246 and 248 welded to its ends, the plates further having cutout sections 250 so that they can be secured along the inner sides of side sections 252 and 254 of back frame 26 as shown in FIGS. 8 and 9 . Preferably, plate 246 is bolted or otherwise secured to side section 252 in combination with L-shaped back frame connector link 212 also on side section 252 , while plate 248 is similarly bolted to side section 254 in combination with L-shaped back frame connector link 212 also on side section 254 . Preferably attached by welding extending downwardly from bar 242 is short extension bar member 258 , having ring 260 secured to its lower end of bar 258 , so that the end of externally threaded spindle 241 may be pivotably secured to ring 260 via pin 262 . A controller 280 , shown in FIG. 24 and described in greater detail below, is then also operably connected both to lift frame and footrest motor or actuator 74 as well as seat frame motor or actuator 238 to control the overall movements of the chair frame.
[0087] FIGS. 15-21 illustrate chair 20 of the invention in a various different retracted or reclined positions. Such Figures do not include arm frames 28 ; however, the lift chair features of the invention are shown in FIGS. 22 and 23 , where chair assembly 23 is shown supported on C-shaped pieces 62 and 63 in a lifted and forwardly tilted position. FIGS. 15-17 are front, back and side views of chair 20 in a fully upright position. When back frame 26 is in such an upright position, internally threaded sleeve 240 of back actuator or motor 238 is extended from threaded spindle 241 . This is also evident in FIGS. 7 and 8 , which show just the seat and back frame portions of the chair assembly, while in FIG. 9 as well as in FIGS. 1, 18 and 19 , where back frame 26 is in a fully reclined position, internally threaded sleeve 240 in now rotated so externally threaded spindle 241 is screwed or threaded into it, so that it is effectively by retracting causing the back frame to recline. In addition, bar 258 is extending substantially directly downwardly from seat frame 26 when sleeve 240 rotates and spindle 241 is expanded out of it and pivots forwardly when the seat frame 26 is reclined (see FIG. 19 ). Actuator 238 may also pivot slightly on bracket 236 attached to bar 230 to which actuator 238 is pivotably connected as the spindle 241 is moved in and out of sleeve 240 to move back frame 26 . In addition, C-shaped bar sections 62 and 63 are supporting chair 20 or act to support the chair on the ground surface in addition to rear crossbar 34 and bars 38 and 39 . Recliner mechanism 104 is also in retracted position, with footrest 27 inclined substantially vertical in relation to the ground surface and footrest links 164 , 172 , 176 , and 182 , which are connected in a scissors-like or so-called pantograph arrangement, being pivoted so that they are substantially more vertical than horizontal. Link 134 is also pivoted downwardly from seat frame connector plate 190 , away from stop 135 . Finally, as best shown in FIG. 2 , threaded sleeve 75 is partially but not completely extended from spindle 76 when footrest 27 is completely retracted.
[0088] When controller 280 , shown in FIG. 24 , is used to activate motor 74 to move the chair from an upright position shown in FIGS. 15-17 to a reclined position such as shown in FIGS. 1, 18 , and 19 , spindle 75 is retracted in sleeve 76 , while L-shaped bracket 78 is pulled rearwardly along with spindle 75 by pivoting on pin 82 securing bracket 78 to bracket 80 on C-shaped section 64 of lift assembly 64 . L-shaped bracket 78 also pulls C-shaped bracket 98 , which in turn is connected to seat frame 24 and also puts tension on the seat frame to be pulled rearwardly. Seat frame 24 , which is pivotably mounted to arm frames 28 by recliner mechanism 104 , in turn is also pulled rearwardly, with links 134 , 156 , and 182 (as best shown in FIGS. 5 and 6 ) pivotably connected to seat connector plates 190 pivoting in a counterclockwise direction when viewed from arm frames 26 on pivot points 198 , 200 , and 192 , respectively. Pivoting of link 156 also causes 160 and 164 to pivot forwardly, which movement further causes scissors style pivoting links 172 , 176 , and 182 to pivot with respect to one another, forcing footrest 27 to be pushed upwardly and outwardly away from the front of chair 20 until the footrest is in a substantially horizontal position. Thus, when motor 74 is activated, seat frame 24 is pulled rearwardly and footrest 27 is pushed upwardly and outwardly. At the same time, back frame 26 and electrical motor 238 , which is pivotably attached to both seat frame 24 and back frame 26 , moves rearwardly along with seat frame 24 . Such feature is important to the operation of the invention as a whole, since if motor 238 was mounted stationary with respect to the lift frame or in some other manner, seat frame 24 could not move rearwardly without coming into contact with and damaging motor 238 or vice versa.
[0089] At approximately the same point at which footrest 27 reaches a substantially horizontal position, link 134 will have pivoted so that it is now prevented from further pivoting by stop 135 , see FIG. 16 . Thus, rather than seat frame 24 being pulled further rearwardly, the force continued to be applied by motor 238 now causes links 130 , 142 , and 150 , as well as 160 to pivot upwardly, and for pivot 144 connecting link 142 to slide 146 in link 134 to move rearwardly in such slide 146 . In particular, L-shaped links 130 and 150 are pivotably linked to opposite ends of link 138 , so that such links will pivot or rotate in unison. See in particular FIG. 19 . Such links will pivot upwardly until bar 130 has pivoted so that it is abutting stop 131 , shown in FIG. 16 , at which point further upward movement is prevented and spindle 75 is arranged so that it will be substantially completely retracted into sleeve 76 , and the chair will have reached a fully reclined position. At the same time, the front end of seat frame will be moving on C-bracket 98 , which pivots somewhat downwardly in response to further pulling on bracket 99 by such actuator 74 . Again, motor 74 will simply move upwardly along with seat frame 24 , so that motor 74 remains in substantially the same position relative to seat frame 24 at all times. Furthermore, back frame 26 can be moved to any pivoted position completely independently of the position of footrest 27 and seat frame 24 . This feature is illustrated by comparing FIGS. 18-19 , where back frame 26 is in a completely reclined position, with FIGS. 20 and 21 , where back frame 26 is in an upright position. In all of such FIGS., footrest 27 and seat frame 24 are in a fully reclined position, while back frame 26 has been pivoted into either an upright or reclined position by actuator 238 which is controlled by controller 280 . If desired, chair frame 23 could be moved to a lift position, wherein lift assembly 22 is extended as shown in FIG. 3 and chair frame 23 is lifted upwardly and tilted forwardly, while back frame 26 remains in a completely reclined position. In FIGS. 13 and 14 , a fully reclined or bed-like position is also shown, with the difference being in the arrangement back frame 26 with respect to the linkage mechanism 104 which is stronger than the linkage shown with respect to the first embodiment of the invention. Similarly, in FIGS. 25 and 27 - 28 , the chair with the back frame having a second alternative linkage system including stabilizing bar 220 is also in a fully reclined position. Such fully reclined position is essentially the Trendelenburg position, wherein the operator's legs are higher than his or her heart, which position is often desirable. However, the chair can also be moved to a reclining position, wherein the legs are not higher than the heart, either by not reclining the footrest mechanism all the way, or alternatively by pivoting the back frame upwardly, which will lift the occupant's torso upwardly. To return chair 20 to a non-reclined position, links 130 and 150 will pivot downwardly in a clockwise direction until they are prevented from further pivoting by stops 133 and 151 , respectively. During this period, seat frame 24 and footrest 27 will be moving generally in a downward direction. Bar 98 will also pivot upwardly or forwardly as the seat frame is lowered. Once links 130 and 150 hit stops 133 and 151 , respectively, the seat frame will move forwardly as the footrest 27 continues to be pulled inwardly towards chair 20 until it is again substantially vertical and seat frame 24 has returned to its original position.
[0090] The ability of the seat frame to pivot rearwardly with the footrest results in a significantly more maneuverable and comfortable recliner and/or lift chair design than is available in the prior art. In chairs where the seat frame does not move in relation to the footrest, the resulting orientation is often uncomfortable for most users and furthermore it cannot be augmented to meet the comfort or medical needs of individual users. For example, as shown in FIG. 19 , a person lying in chair 20 will be in the so-called Trendelenburg position, which is a position where such persons legs are higher than his or her heart. For persons who do not require or desire such a position, the back frame can be moved to a position such as shown in FIG. 20 . In addition, as is shown in FIG. 26 , the user may pivot the chair into a so-called “zero gravity” or back relief position, which provides complete support for the user and relieves pressure from the spine. Note in particular that in FIG. 26 , the footrest is not completely horizontal but is at a slight forward incline or angle. In another novel feature of the invention, the present inventors have conceived of a simple yet extremely effective means for adjusting the angle of the footrest based on the desires and needs of individual purchaser of chair 20 . Normally, when the chair is being moved to a reclining position, as explained above, the footrest 27 will move upwardly and the chair seat frame 24 will move rearwardly on linkage mechanism 104 until the footrest has reached approximately a horizontal position. However, as is best shown in FIG. 29 , stop 250 is positioned extending inwardly from the rear edge of seat frame connector plate 120 . As a result, just before footrest 27 reaches a horizontal position, link 206 will move rearwardly into contact with stop 250 , which will prevent the linkage mechanism from further rearward movement, and footrest 27 will be deployed at an angle that is slightly less than horizontal. It should be evident, therefore, that by replacing stop 250 with a similar stop having either a slightly greater or slightly reduced diameter, the angle at which footrest 27 ultimately comes to rest can be adjusted slightly. The use of stop 250 provides a simple and effective means for enabling the footrest to be slightly inclined, and so as a result chair 20 can also be adjusted so that it is in substantially a zero-gravity position, such as that shown in FIG. 26 , wherein all of the weight of the chair occupant has been relieved from the spine, and the body is essentially in a stress-free position. Depending upon the physical characteristics of an individual user of chair 20 , the zero-gravity position may be slightly different, and thus the ability to adjust the angle of the back frame 26 independent of the position of both the seat frame and footrest, plus the ability to slightly adjust the angle of the footrest accordingly by changing the diameter of stop 250 , a more user-friendly and easily adjustable lift and recliner comprising a substantial advance in the art has resulted.
[0091] The controller 280 provided to control or activate motors 74 and 238 , shown in FIG. 24 , may be of a conventional type, and preferably will have separate buttons for reclining the seat back 281 , moving the seat back to an upright position 282 , moving the chair to a reclining position with the footrest extended 283 , moving the footrest to a retracted position 284 , activating the lift assembly so that the chair frame is raised and tilted forwardly 285 , and for returning the lift assembly to a retracted position 286 . Wire 287 connects controller 280 to the actuators, although a wireless connection may also be used if preferred. A light means 288 may also be provided to indicate activation or multiple light means could be provided to indicate modes of operation.
[0092] While the present invention has been described at some length and with some particularity with respect to the several described embodiments, it is not intended that it should be limited to any such particulars or embodiments or any particular embodiment, but it is to be construed with references to the appended claims so as to provide the broadest possible interpretation of such claims in view of the prior art and, therefore, to effectively encompass the intended scope of the invention.
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A combination lift chair and reclining chair having additional seating and reclining positions is provided with two separate motors and linkages enabling the chair back to be independently placed in various positions and the seat separately movable with the footrest and elevated once the footrest has reached full deployment using the same motor.
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CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Belgium Application No. 2015/0181, filed Jul. 8, 2015, the contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to agricultural balers, and, more particularly, to agricultural square balers having a monitoring system for the knotting/triggering systems.
BACKGROUND OF THE INVENTION
[0003] Agricultural harvesting machines, such as balers, are used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. In the case of hay, a mower-conditioner is typically used to cut and condition the crop material for windrow drying in the sun. In the case of straw, an agricultural combine discharges non-grain crop material from the rear of the combine defining the straw (such as wheat or oat straw) which is to be picked up by the baler. The cut crop material is typically raked and dried, and a baler, such as a large square baler or round baler, straddles the windrows and travels along the windrows to pick up the crop material and form it into bales.
[0004] On a large square baler, a pickup unit at the front of the baler gathers the cut and windrowed crop material from the ground. The pickup unit includes a pickup roll, and optionally may include other components such as side shields, stub augers, wind guard, etc.
[0005] A packer unit is used to move the crop material from the pickup unit to a duct or pre-compression chamber. The packer unit forms a wad of crop within the pre-compression chamber, which is then transferred to a main bale chamber. (For purposes of discussion, the charge of crop material within the pre-compression chamber will be termed a “wad”, and the charge of crop material after being compressed within the main bale chamber will be termed a “flake”). Typically such a packer unit includes packer tines or forks to move the crop material from the pickup unit into the pre-compression chamber. Instead of a packer unit it is also known to use a rotor cutter unit, which chops the crop material into smaller pieces.
[0006] A stuffer unit transfers the wad of crop material in charges from the pre-compression chamber to the main bale chamber. Typically such a stuffer unit includes stuffer forks which are used to move the wad of crop material from the pre-compression chamber to the main bale chamber, in sequence with the reciprocating action of a plunger within the main bale chamber.
[0007] In the main bale chamber, the plunger compresses the wad of crop material into flakes to form a bale and, at the same time, gradually advances the bale toward the outlet of the bale chamber. The plunger reciprocates, back and forth, toward and away from the discharge end of the baler. The plunger may include a number of rollers, which extend laterally outward from the sides of the plunger. The rollers on each side of the plunger are received within a respective plunger slot formed in the sidewalls of the bale chamber, with the plunger slots guiding the plunger during the reciprocating movements.
[0008] When enough flakes have been added and the bale reaches a full (or other predetermined) size, a number of knotters and needles are actuated which wrap and tie twine, cord or the like around the bale while it is still in the main bale chamber. The twine is carried to the knotters by the needles that pivot through the bale chamber to the knotters. The twine is grasped, cut and tied, and the formed baled is ejected out the back of the baler as a new bale is formed.
[0009] In EP1066747 a baler is disclosed having a sensor and timer operations, including a trip arm related to a stuffer mechanism that activates the sensor. However, the sensor is not for a knotter mechanism.
[0010] In EP2011385 it is disclosed that a blast of air can be delivered at the tip of the needles to dislodge crop material as they arrive at the knotters having passed through the bale chamber.
[0011] In U.S. Pat. No. 465,235 there is disclosed a monitoring system for detecting the malfunctioning of a knotting mechanism of a baler. However the system does not monitor or control multiple features.
[0012] In EP2803259 a tractor and baler combination is shown where a control unit is able to control the drive connection between the tractor and baler when a critical operating state of the pickup or knotting mechanism of the baler is detected.
[0013] What is needed in the art is an agricultural baler that can effectively monitor multiple functions of the knotting system in an efficient manner.
SUMMARY OF THE INVENTION
[0014] In accordance with an aspect of the present invention, there is provided an agricultural baler with an efficient usage of a single sensor relative to knotter functioning.
[0015] In accordance with another aspect of the present invention, there is provided an agricultural baler including a main bale chamber, needles, knotters, a triggering system, a knotter lock, a blow-off mechanism, and a monitoring system. The needles are coupled to the main bale chamber, and thread twine around a formed bale. The knotters receive the twine from the needles and tie the twine. The triggering system activates the needles and the knotters. The knotter lock is a manual lock of the triggering system thereby preventing the needles and the knotters from being triggered. The blow-off mechanism directs a flow of air at the knotters and/or the needles when moved to the knotters. The monitoring system has a single sensor that provides signals indicating a normal operation of the knotters, an engagement of the knotter lock, and a time to trigger the blow-off mechanism for a predetermined amount of time.
[0016] An advantage of the agricultural baler is that it is able to monitor several functions using one sensor.
[0017] Another advantage is that the engagement of the knotter lock is detected to help prevent operation of the baler when the knotter lock is engaged. Then, a knotter locked operation message can be send to a display, warning the operator of a traction unit (e.g. a tractor) that the knotter lock is engaged. Alternatively or additionally, a sound can be heard or a light can be flashed in the operators cab to warn the operator. When the knotter lock is disengaged, normal working of the knotters and needles is possible, and operation of the baler and traction unit can now continue.
[0018] Yet another advantage is that the agricultural baler times the blowing off of the knotters and the needles at the appropriate time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
[0020] FIG. 1 is a perspective cutaway view showing internal workings of a large square baler comprising a monitoring system, in accordance with an exemplary embodiment of the present invention;
[0021] FIG. 2 is a side partial view of the baler of FIG. 1 illustrating an embodiment of a sensor used in cooperation with a triggering system, in accordance with an exemplary embodiment of the present invention;
[0022] FIG. 3 is another side view of the triggering system of FIG. 2 , when a bale knotting operation is being triggered, in accordance with an exemplary embodiment of the present invention;
[0023] FIG. 4 is yet another side view of the triggering system of FIGS. 2 and 3 with a knotter lock engaged, in accordance with an exemplary embodiment of the present invention; and
[0024] FIG. 5 is a block diagram illustrating connections and functions of the monitoring system using the sensor with the triggering system of FIGS. 2-4 in the baler of FIG. 1 , in accordance with an exemplary embodiment of the present invention.
[0025] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Referring now to the drawings, and more particularly to FIG. 1 , there is shown a perspective cutaway view showing the internal workings of a large square baler 10 , in accordance with an exemplary embodiment of the present invention. The baler 10 operates on a two stage feeding system. Crop material is lifted from windrows into the baler 10 using a pickup unit 12 . The pickup unit 12 includes a rotating pickup roll 14 with tines 16 which move the crop rearward toward a packer unit 18 . An optional pair of stub augers (one of which is shown, but not numbered) are positioned above the pickup roll 14 to move the crop material laterally inward. The packer unit 18 includes packer tines 20 which push the crop into a pre-compression chamber 22 to form a wad of crop material. The packer tines 20 intertwine the crop together and pack the crop within the pre-compression chamber 22 . The pre-compression chamber 22 and the packer tines 20 function as the first stage for crop compression. Once the pressure in the pre-compression chamber 22 reaches a predetermined sensed value, a stuffer unit 24 moves the wad of crop from the pre-compression chamber 22 to a main bale chamber 26 . The stuffer unit 24 includes stuffer forks 28 which thrust the wad of crop directly in front of a plunger 30 , which reciprocates within the main bale chamber 26 and compresses the wad of crop into a flake. The stuffer forks 28 return to their original stationary state after the wad of material has been moved into the main bale chamber 26 . The plunger 30 compresses the wads of crop into flakes to form a bale and, at the same time, gradually advances the bale toward an outlet 32 of the main bale chamber 26 . The main bale chamber 26 and the plunger 30 function as the second stage for crop compression. When enough flakes have been added and the bale reaches a full (or other predetermined) size, knotters 34 are actuated which wrap and tie twine around the bale while it is still in the main bale chamber 26 . Needles 36 bring the lower twine up to the knotters 34 and the tying process takes place. The twine is cut and the formed bale is ejected from a discharge chute 38 as a new bale is formed.
[0027] The plunger 30 is connected via a crank arm 40 with a gear box 42 . The gear box 42 is driven by a flywheel 44 , which in turn is connected via a drive shaft 46 with the power take-off (PTO) coupler 48 . The PTO coupler 48 is detachably connected with the PTO spline at the rear of the traction unit, such as a tractor (not shown). The PTO coupler 48 , the drive shaft 46 , and the flywheel 44 together define a portion of a driveline 50 , which provides rotative power to the gearbox 42 . The flywheel 44 has a sufficient mass to carry the plunger 30 through a compression stroke as power is applied to the drive shaft 46 by the traction unit (not shown).
[0028] Now, additionally referring to FIGS. 2-5 , there are shown side views of a triggering system 52 and a monitoring system 58 (shown schematically in FIG. 5 ) associated therewith and located on the agricultural baler 10 , in accordance with an exemplary embodiment of the present invention. The triggering system 52 is generally located on a top of the main bale chamber 26 along with a knotter lock 54 and a blow-off mechanism 56 (shown schematically in FIG. 5 ). The monitoring system 58 interacts with elements of the triggering system 52 and part of the monitoring system 58 may be located in a traction unit, such as a tractor (not shown) that is pulling and providing power to the agricultural baler 10 .
[0029] The triggering system 52 includes a star wheel 60 , a coupling wheel 62 , a pivoting gauge 64 , a trip lever 66 , and a spring 68 . The star wheel 60 engages the crop material along a top side of the bale as the bale is moved in the main bale chamber 26 . The star wheel 60 moves proportionally with the length of the bales causing the coupling wheel 62 to move the pivoting gauge 64 in an upward direction. When the pivoting gauge 64 is raised to a release point 70 (as seen in FIG. 3 ), the tension on the spring 68 causes the bottom portion of the trip lever 66 to be pulled to the right and the triggering event occurs for the bale tying sequence to begin. This is precluded from happening if the knotter lock 54 is engaged (as shown in FIG. 4 ), where a handle 72 is moved in a clockwise direction causing a locking portion 74 to engage part of the triggering system 52 . The knotter lock 54 is engaged for purposes of safety when maintenance is being done to the baler 10 to preclude the triggering of the operation of the needles 36 and the knotters 34 . If the knotter lock 54 is left engaged and the agricultural baler 10 is operated then no knotting operation takes place and the operator may have compressed a significant amount of crop material and wasted twine and time, and a need to then re-bale the crop material.
[0030] The monitoring system 58 includes a sensor 76 , a controller 78 , and a display 80 . The display 80 may be part of the traction unit and in an operator cab of the traction unit for conveying information to the operator. The controller 78 may be a standalone unit or its functions may be carried by another controller on the agricultural baler, or by way of dedicated circuits. The controller 78 executes software instructions to perform the functionality of the controller 78 described herein. Such software instructions are stored on a computer-readable tangible medium, either internal to the controller 78 or external thereto. The controller 78 loads such software instructions and executes them to perform the functionality described herein. The sensor 76 is a single sensor that carries out several functions because of its positioning and the data available to it as a result of its desirable positioning. The sensor 76 may be a proximity sensor, an optical sensor, a contact sensor, a magnetic sensor, or other type of sensor that can serve the purposes discussed herein. The sensor 76 provides a signal or signals to the controller 78 based on a sensed parameter or parameters. The controller 78 interprets the signal or signals received from the sensor 76 .
[0031] In FIG. 2 , the knotter lock 54 is in an unengaged position with locking portion 74 apart from the sensor 76 , and the trip lever 66 is also apart from the sensor 76 . This results in either a non-signal provided from the sensor 76 to the controller 78 or a signal indicating that there is nothing detected proximate to the sensor 76 , so that the controller 78 would interpret this signal as the knotter lock 54 being disengaged and no warning would be sent to the display 80 by the controller 78 . When the star wheel 60 is advanced and the pivoting gauge 64 is advanced, as shown in FIG. 3 , this causes the trip lever 66 to move proximate to the sensor 76 and the proximity of the trip lever 66 is detected and a signal is generated by the sensor 76 and transmitted to the controller 78 . Meanwhile the needles 36 move through the main bale chamber 26 and the twine is conveyed to the knotters 34 and the bale is tied. As this is happening the triggering system is reset with the trip lever 66 being pulled back allowing the pivoting gauge 64 to pivot downwardly until the top of the pivoting gauge 64 settles against the coupling wheel 62 . This movement of course causes the trip lever 66 to move away from the sensor 76 , back to a position as shown in FIG. 2 . Since the trip lever 66 is no longer proximate to the sensor 76 , the signal generated by the sensor 76 and provided to the controller 78 indicates to the controller 78 that a momentary presence, of less than one second to a few seconds in duration, has occurred and that the detection is of a normal operation of the baler 10 and more specifically of the knotter system composed of the knotters 34 , the needles 36 , and the triggering system 52 .
[0032] When the signal sent by the sensor 76 is representative of the movement/presence of the trip lever 66 , not only is a signal indicating a normal operation of the baler 10 sent to the display 80 by the controller 78 , but also a count that another bale has been completed can be sent. Yet further, when the triggering event occurs the controller 78 sends a signal to the blow-off mechanism 56 to cause air to flow on the knotters 34 and/or a distal end of the needles 36 as they become proximate to the knotters 34 having traveled through the main bale chamber 26 , and they may have become fouled with some crop matter, which needs to be removed. This airflow or blast of air helps to ensure a cleaning action and a resulting reliable handoff of the twine to the knotters 34 so that they can tie the knots and cut the twine of the completed bale.
[0033] When the knotter lock 54 is in the locked position, as shown in FIG. 4 , the sensor 76 provides a constant signal indicating the proximity of the knotter lock 54 to the controller 78 . The constant signal is interpreted by the controller 78 as the knotter lock 54 remaining in an engaged position and hence information to that effect is sent to the display 80 by the controller 78 . It is also contemplated that an alarm signal may be initiated by the controller 78 in the event that movement of the traction vehicle takes place while the indication of the engagement of the knotter lock 54 continues. The controller 78 may transmit the alarm signal to the display 80 for display thereon, or it may alternatively transmit the alarm signal to a speaker (as a sound alarm), to a lamp (as a (flashing) light alarm), or a combination of them in the operator cab to warn the operator that the knotter lock 54 is still in the engaged position and that forward driving of the traction vehicle should be stopped.
[0034] The triggering system 52 , specifically the controller 78 , detects the normal operation of the knotter 34 mechanism, and transmits a warning signal in case the knotter lock 54 is activated. (Without this advantage there is nothing on the machine to warn the operator if the lock 54 is still activated after servicing the knotters 34 . This is disadvantageous since a very long bale will be produced until the operator notices that the knotters 34 are not functioning.) Further, the triggering system 52 , specifically the controller 78 , transmits a signal to the blow-off mechanism 56 to operate the blow-off mechanism 56 of the knotters 34 . (Advantageously the blow-off system 56 does not need to be constantly operable.) When the signal of the tripping is used to also operate the blow-off mechanism 56 , it will be able to blow air on the knotters 34 when the needles 36 are coming up (operated by the tripping mechanism 52 ) and will clean the needles 36 when it is actually needed (which is just before the needles 36 reach the knotters 34 ).
[0035] Stated in another way, the desirable positioning of the sensor 76 allows the sensor 76 to detect three different things and allows the controller 78 to control various aspects of the monitoring system 58 accordingly. The sensor 76 looks for the trip lever 66 movement in the knotter cycle. If the trip lever 66 is activated it would pass the sensor 76 for about one second. The sensor 76 generates a signal that can be used by the controller 78 to set/reset the knotter cycle. So the software executed by the controller 78 knows it is a knotter cycle (and displays this on the monitor 80 ). If someone activates the knotter lock safety 54 , a portion 74 comes in front of the sensor 76 . The sensor 76 generates a signal that lasts longer than the one second. The software executed by the controller 78 knows now it is the knotter lock safety 54 , which is activated, and provides a warning signal to the display monitor 80 . If the operator forgets to reset the knotter lock safety 54 , he would see the warning on the monitor 80 . He will know that he should reset or disengage the knotter lock safety 54 first before he drives on to create an extremely long bale, which will have to be re-baled. The first signal (the short one, activated by the trip lever 66 ) generated by the sensor 76 can also be used by the controller 78 to activate the blow-off mechanism 56 . This ensures that the knotters 34 will be cleaned just before a knot is made.
[0036] While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
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An agricultural baler includes a main bale chamber, needles, knotters, a triggering system, a knotter lock, a blow-off mechanism, and a monitoring system. The needles are coupled to the main bale chamber and thread twine around a formed bale. The knotters receive the twine from the needles and tie the twine. The triggering system is for activating the needles and the knotters. The knotter lock is a manual lock of the triggering system thereby preventing the needles and the knotters from being triggered. The blow-off mechanism directs a flow of air at the knotters and the needles. The monitoring system has a single sensor that provides signals indicating a normal operation of the knotters, and whether the knotter lock is engaged.
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This application is a continuation in part of application, Ser. No. 502,058, filed Aug. 30, 1974 now U.S. Pat. No. 3,920,266 entitled DUAL PURPOSE TRAILER SWAY CONTROL DEVICE AND SAFETY CONNECTOR FOR MOUNTING ON EITHER THE TOWED OR TOWING VEHICLE, by the same inventor and an improvement on U.S. Pat. No. 3,871,686, issued Mar. 18, 1975.
BACKGROUND OF THE INVENTION
The use of towed trailers behind automobiles and lightweight trucks has become quite commonplace and the hazards associated with such vehicular combinations are well known. A particularly dangerous characteristic of the towed trailer is its tendency to sway from side to side under conditions initiated by sudden turns, cross winds, air drafts produced by passing trucks, improper loading of the trailers, among other things. Certain combinations of various parameters such as the length of the trailer tongue, the weight of the load, and the surface of the highway increase the tendency for the trailer to sway and even increase the intensity or amplitude of the swaying action once it has started. Under such conditions it is difficult if not impossible for the driver of the towing vehicle to maintain control of his vehicle. The combination of the towing vehicle and the trailer in the presence of such critically related parameters contributes an unstable mechanical system.
Prior art disclosures have been limited in scope and have provided for devices only to lessen or prevent the swaying motion of trailers. Some of these devices are complicated in structure involving pulleys or spools, brake shoes, telescoping structures employing friction or hydraulic damping means and usually have numerous parts requiring periodic replacement otherwise the devices may become dangerous within themselves. Furthermore, some prior art devices employ only one means of connection on only one side of the longitudinal axis of the towed trailer to obtain sway control presenting a potentially dangerous condition should the trailer tongue break away from the towing vehicle when in motion. Nearly all of the prior art structures require component parts that are difficult to install an require complicated instructions for mounting and operation.
SUMMARY OF THE INVENTION
In accordance with the invention claimed, improved mounting structures for a sway control device are provided having one or more fixed, curved or arcuate surfaces adapted to be mounted on the hitch bracket of a towing vehicle interconnected by flexible operating means secured to opposite sides of a trailer being towed. Adjustment means are provided to cause tension in the flexible means inducing frictional restraint of movement of the flexible means about the curved or arcuate surfaces coincident with any lateral movement of the towed vehicle.
It is, therefore, one object of this invention to provide an improved sway control device for mounting on the towing vehicle.
Another object of this invention is to provide such improved structures and components therefor for mounting to a hitch bracket adapted to be secured to a towing vehicle.
A further object of this invention is to provide a cross member secured to the hitch bracket of a towing vehicle to significantly increase the area of the hitch bracket and to which curved or arcuate surfaces or other suitable friction restraining constructions are fixedly secured to confine and limit movement of the trailer coupler in event of accidental disconnection of the pivotal hitch connection.
A still further object of this invention is to provide structures utilizing flexible means moving over friction inducing surfaces to cause frictional damping to restrain pivotal movement of a hitch coupler about a conventional hitch ball.
A still further object of this invention is to provide sway control structures that are readily secured or removed from the hitch of a towing vehicle by employing simple mounting brackets that can be permanently welded to a hitch bracket at the factory prior to installation on a towing vehicle to save installation costs.
A still further object of this invention is to provide a sway control device having structures attached to a towing hitch bracket to avoid obstruction that may be prevalent on trailer tongues.
A still further object of this invention is to provide a dual function structure utilized in conjunction with safety chains for a trailer sway control device that would prevent the tongue of a trailer from dropping to the road in event it accidentally became disconnected from the towing vehicle while being towed.
A still further object of this invention is to provide a sway control device structure mountable on a towing vehicle and connectable to a plurality of trailers.
A still further object of this invention is to provide a sway control device with structures that require little or no maintenance or periodic adjustments.
A still further object of this invention is to provide a sway control device with structures which will not readily wear out or require replacement of moving parts.
A still further object of this invention is to provide a sway control device with structures that also serve the dual function of a safety connector between the towing vehicle and the trailer being towed.
A still further object of this invention is to provide a sway control device which is easily installed, connected and adjusted for operation.
Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming part of this specification.
BRIEF DESCRIPTION OF THE DRAWING
The present invention may be more readily described by reference to the accompanying drawing in which:
FIG. 1 is a perspective view showing one model or embodiment of improved sway control structures mounted on the conventional hitch bracket of a towing vehicle and connected to the tongue of a trailer.
FIG. 2 is a view similar to FIG. 1 with the sway control device in position over the hitch ball of the hitch bracket.
FIG. 3 shows a partial plan view of a sway control device similar to that shown in FIG. 1 with the towing vehicle in an angular position to the towed vehicle.
FIG. 4 is an enlarged partial view of the connector tensioning device shown in FIGS. 1-3.
FIG. 5 is an enlarged partial view of the connector tensioning device shown in FIGS. 1-3.
FIG. 5 is a top view of a modifiction of the fraition bearing curved surface of the sway control device shown in FIGS. 1-3.
FIG. 6 is a front view of the structure shown in FIG. 5 showing mounting angle brackets.
FIG. 7 is an end view of the structure shown in FIG. 6.
FIG. 8 is a further modification of the sway control device shown in FIGS. 1-7 employing brackets for holding the flexible connector in place on the fixed curved surfaces of the sway control device.
FIG. 9 is a front view of the structure shown in FIG. 8.
FIG. 10 is an end view of the structure shown in FIG. 9.
FIG. 11 is a top plan view of a further modification of the sway control device shown in FIGS. 1-10 connected to the hitch bracket of a towing vehicle.
FIG. 12 is a front view of a further modification of the sway control device shown in FIG. 11 omitting the middle section of the curved surface mounted on the hitch bracket of the towing vehicle.
FIG. 13 is a cross-sectional view of an adaptor shown in FIG. 11 for connecting the sway control to a single tongue trailer.
FIG. 14 is a still further modification of the sway control devices shown in FIGS. 1-13 secured to the trailer hitch of a towing vehicle.
FIG. 15 is a further modification of the sway control devices shown in FIGS. 1-14 wherein the curved surfaces are replaced with rotors.
FIG. 16 is a still further modification of the sway control devices shown in FIGS. 1-15 wherein a plurality of curved surfaces are mounted on the tongue of the towed vehicle.
FIG. 17 is a partial end view of the bracket for mounting the curved friction damping surfaces on the tongue of the trailer.
FIG. 18 is a cross-sectional view of FIG. 16 taken along the line 18--18.
FIG. 19 is an exploded perspective view of a further modification of the sway control device shown in FIGS. 5-10 adapted for use with equalizer heads.
FIG. 20 is an end view of the structure shown in FIG. 19 in assembled relationship.
FIG. 21 is an exploded perspective view of a further modifiction of the sway control device shown in FIG. 19 in association with an equalizer head.
FIG. 22 is a perspective assembled view of the structure shown in FIG. 21.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more particularly to the drawings by characters of reference, FIGS. 1-3 disclose a sway control device 10 comprising curved surface 18 and plate 20 hereinafter explained mounted on a conventional towing hitch 11 of a vehicle 12 having a hitch ball 14 bolted thereto to extend substantially vertically therefrom for receiving a hitching ball socket or coupler 15. Coupler 15 has its rearward extending shank 16 fixed to the forward joined ends of a pair of hitching arms 17 of a trailing vehicle (not shown) by suitable means to form a part of the tongue of a trailer.
The sway control device 10 comprises one or more curved surfaces 18 fixedly mounted on either the towing hitch 11 of the towing vehicle, as shown in FIGS. 1-3, or on the hitching arms 17 or ball socket shank 16 of the towed vehicle, as shown in U.S. patent application, Ser. No. 502,058, filed Aug. 30, 1974 by William L. Rendessy.
FIGS. 1-3 illustrate the curved surface 18 comprising a cup shaped metallic strip like configuration formed to curve partly around the hitch ball 14 to provide on its outer circumference friction bearing surfaces 18A, 18B and 18C for a flexible connector 19 herein shown in a belt like configuration.
The curved surface 18 is suitably connected such as by welding on one edge to a flat plate 20 which is secured in turn to the trailer hitch bracket 11. Flat plate 20C is provided with an aperture 21C therethrough, as shown in FIG. 5, for receiving the hitch ball 14.
It should be recognized that the flat plate 20C and curved convex surface 18 may be welded or otherwise secured to the towing hitch 11 or to the flat surface of a step bumper of a truck and sold as a unit or part of the towing hitch bracket or independently thereof as a separate sway control device for attachment to the towing hitch bracket or hitching arms 17 of a towed vehicle.
The flexible connector 19 may comprise a belt or cable formed of suitable material and is available in the marketplace having flexibility and wear characteristics of tough heavy duty conveyor belting. This connector is placed over the curved surface 18 of the sway control device 10 around its outer circumferential surfaces 18A, 18B and 18C of FIG. 1 and suitably connected at one end by means of a toggle release or clamp 22 to the hitching arms 17 of the towed vehicle and at its second end through a turnbuckle 23 and hook 24 to the other hitching arm 17 of the towed vehicle. Turnbuckle 23 is utilized to adjust the belt or cable as desired.
Turnbuckle 23 comprises a cylindrical housing 25 having a longitudinal slot 26 with an axial threaded opening at one end thereof. The other end of the housing is provided with a pair of juxtapositioned longitudinally extending arms 27 which are arranged to have extending therebetween in bolted connection thereto one end of belt 19, as shown in FIGS. 1 and 2. A single stud 28 is threaded into the axial opening in housing 25 of the turnbuckle which in turn is pivotally attached to hitching arms 17 of the towed vehicle by a simple hook and eye arrangement, as shown. Since only one stud is used, the turnbuckle has to be disconnected to turn.
The toggle release 22 is bolted or riveted to the other end of belt 19 as shown in FIGS. 1 and 2, and connects by means of a hook 29 to an eye bolt 30 which is attached to the hitching arms 17 of the towed vehicle. This toggle release provides a means for quickly applying or releasing tension in belt 19 for tightening or disconnecting the sway control device 10 from the towed or towing vehicle.
As shown in FIG. 4, the toggle release comprises an elongated outer member 31 having an inner member 32 pivotaly attached at one end for nesting inside of member 31 with hook 29 pivotally mounted within outer member 31. Outer member 31 is in the form of two parallel flat metal straps joined together by transverse metal pins 33 tightly holding between the straps the end of belt 19.
When inner member 32 of the toggle release is fully nested inside outer member 31, it is in a below center position. Reference is made to the patent application referred to above for more detail of a similar toggle release 22 which toggle releases are well known in the art and will not be described in more detail herein for simplicity purposes.
In the nested position and with hook 29 attached to a fixed point on the hitching arm 17, as shown in FIGS. 1 and 2, tension is applied belt 19. Member 32 is kept in the dotted position by hook 29 dropping below pin 34, as shown in FIG. 4, which causes it and member 31 to form a below center locket toggle configuration. To release the toggle end 35A of plate 35 must move hook 29 back over center to open the lock in a manner well known in the art.
To release toggle release 22 in the presence of belt tension, the raised end 35A of plate 35 may be grasped and forced upwardly against the downward force produced by the belt tension. As inner member 32 thus raises in its rotation about pin 34, the effective length of the toggle release assembly increases and relieves the tension. The increased effective length of the toggle release in the fully released position also allows for the disengagement of hook 29 from the ring 30 or other means to which it had been attached.
To prepare sway control device 10 for use, the trailer hitch ball socket is first coupled to the towing vehicle by placing and firmly attaching the coupler over the hitch ball 14. The ends of belt 19 are attached as shown in FIGS. 1 and 2 through hooks 24 and 29 to the hitching arms 17 of the towed vehicle. The intermediate portion 19A of the belt 19 is then placed around the outer circumferential friction bearing curved surface 18 of the sway control device. Thus, belt 19 makes contact with the curved surface 18 of the sway control device when the toggle release 22 is forced to the nested or closed position after turnbuckle 23 is adjusted to produce the desired tension in belt 19 which now follows a curved path beginning at one end of curved surface 19 and passing around its full curved surface, as shown in FIG. 1 to its point of attachment to turnbuckle 23.
As tension in belt 19 is increased, belt 19 bears against curved surface 18 with increasing pressure and the additional force which must be applied to overcome this friction to produce relative displacement between belt 19 and the outer peripheral bearing surface of curved surface 18 is correspondingly increased.
As shown in FIGS. 1, 2 and 3, the curved surface 18 comprises an intermediate curved surface 18A terminating in two similar curved ends 18B and 18C. Each curved end is so configured with its relationship to the coupler as to provide the proper turning arrangement so as to keep the belt 19 free from all obstructions when the towed and towing vehicle assume any angular position.
FIGS. 5, 6 and 7 illustrate a modification of the sway control device 10 wherein the sway control device 10A differs from sway control device 10 by the curved surface 18A being replaced by a substantially straight portion 18D. The curved ends 18B and 18C remaining substantially the same. It should be noted that the flat plate 20C of sway control device 10A may be provided with two spaced right angular brackets 36, 36' provided with aligned apertures 37, 37', respectively. Flanges 36, 36' are welded or bolted to flat plate 20 and are so positioned to fit over and bolted through apertures 37, 37' to the towing hitch bracket 11.
FIGS. 8, 9 and 10 illustrate a further modification of the sway control device of FIGS. 1 and 2 which sway control device 10C is modified merely by fixing brackets 38 to selected positions along the curved surface 18 for maintaining belt 19 in position along the curved surface 18. Plate 20C is provided with an aperture 21C for receiving the hitch ball stud and apertures 21D for bolting to a trailer hitch bracket or step bumper of a truck.
FIG. 11 illustrates a further modification of the sway control devices shown in FIGS. 1-10 wherein the sway control device 10D varies from sway control devices 10 and 10A of FIGS. 1, 2 and 5-7 by utilizing a straight surface 18E for interconnecting curved ends 18B' and 18C'. This surface arrangement may be fixed to, as by welding, flat plate 20C of the sway control device. This sway control device may be welded directly to the hitch bracket 11 of the towing vehicle as shown.
It should be noted that in this modification two turnbuckles 23A may be employed one on each end of belt 19 for tightening the belt around the curved ends 18B' and 18C' of the sway control device with the free ends of the turnbuckles connected to single tongue structure 40 of a towed vehicle. As noted, a tightening lock nut 41 is used with one of the turnbuckles to lick it in place.
FIG. 12 illustrates a modification of the sway control devices shown where the curved surfaces 18B' and 18C' of FIG. 11 are fixed to plate 20C without the interconnecting surface 18E.
FIG. 13 illustrates one form of adaptor 42 for clamping over the tongue 40 of the towed vehicle as shown in FIG. 11. This adaptor clamped to the tongue 40 of the towed vehicle is provided with two apertures 43 for receiving the hook ends 44 of the turnbuckles 23A.
FIG. 14 shows a further modification of the structure of the sway control device illustrated in FIGS. 1 and 2 showing a simple hardware arrangement wherein a simple eye bolt 46 is connected at one end of belt 19 with a turnbuckle arrangement 23B used at the other end for controlling the tension of belt 19 around the curved surface 18A and ends 18B and 18C of the sway control device.
A safety chain 47 may be interconnected with connector 19 as shown in FIG. 14 to keep the tongue of the trailer from dropping to the road bed if the coupler 15 becomes disconnected from the towing vehicle.
It should be noted in FIGS. 12 and 14 that plate 20C increases the width and area of the hitch bracket considerably over the conventional hitch brackets. In the event of breakaway of the coupler from the hitch ball during towing, the inner surfaces of curved surfaces 18B and 18C and 18B' and 18C' will limit lateral movement of the coupler. The straight or curved surfaces 18E and 18A, respectively, will limit forward movement of the coupler. Connector 19 limits rearward movement of the coupler and plate 20C prevents the coupler from dropping to the roadway. Thus, the improved sway control structures disclosed also provide a safety function which heretofore was not possible with the prior art devices.
FIG. 15 discloses a further modification of the structure shown in FIGS. 1-14 and particularly FIG. 11 wherein sway control device 10D comprises rotors 48 and 49 in place of the curved surfaces 18B' and 18C' mounted on plate 20D. Connector 19D is placed over the rotors and connected with hooks 50 and 51 to eye bolts 52, 53, as shown, and operates in substantially the same manner as the structure shown in FIG. 1.
FIGS. 16-18 illustrate a still further modification of sway control devices shown in FIGS. 1-15 wherein device 10E comprises curved surfaces 18F, 18G and 18H mounted on a bracket 60 attached to the tongue of a trailer. The flexible connector 19E is placed in a serpentine manner around curved surfaces 18F, 18G and 18H as shown with its free ends detachably mounted to a hitch bracket 61. The hitch bracket supports the hitch ball 14 as shown in FIG. 17.
It should be recognized that the use of the disclosed sway control devices and component structures eliminates the need for the usual safety chains on towed vehicles since belt 19 serves that purpose and is at least an equivalent in strength. If at all times is around and interconnected with the towed vehicle when taut and thus serves the safety chain purpose.
It should be noted that threaded shank 98 of hitch ball 100 shown in FIG. 12 is mounted through aperture 21C shown in FIGS. 5, 8 and 9 which is centrally located between opposite curved end surfaces 18C and 18B shown in FIG. 6. The shank then extends through an aperture (not shown) provided in hitch bracket 11 to centrally located and to properly position the sway control device such as device 10 of FIG. 1.
Flange 101 of hitch ball 100, FIGS. 9 and 12, secures plate 20C to hitch bracket 11 by tightening nut 99 of threaded shank 98 against the bottom portion of hitch bracket 11. Plate 20C, FIG. 12, can additionally be secured such as by weld 97 to hitch bracket 11 or by brackets 36 and 36' of FIG. 6.
Brackets 36 and 36' of FIG. 6 are of right angular construction having vertically positioned inner surface portions 50 and 50' each provided with one or more apertures oppositely aligned with each other and upper portions 51 and 51' adjacent and parallel to plate 20C. Portions 51 and 51' are each provided with one or more apertures or a single slotted aperture (not shown) to permit increasing or decreasing the distance between surfaces 51 and 51' of FIG. 6 as may be required for mounting onto hitch bracket 11 of FIGS. 2 and 12. Preferably carriage bolts with suitable washers and nuts align apertures 20A and 20A' of FIG. 6 with apertures provided in upper portions of angle brackets 51 and 51' to permit securing of plate 20C to angle brackets 36 and 36'.
Opposite inner surfaces 50 and 50' of brackets 36 and 36' of FIG. 6 are slipped over hitch bracket 11 of FIGS. 2 and 12. Apertures 37 and 37' of FIG. 6 are so positioned underneath the bottom of hitch bracket 11 of FIG. 2 that a bolt (not shown) when placed through aperture 37 extends underneath hitch bracket 11, and through aperture 37' of angle bracket 36. The threaded portion of the bolt is provided with a suitable washer and a nut to sandwich and secure angle brackets 36 and 36' to the sides of hitch bracket 11.
It is to be noted that surface 18E of FIG. 8 of arcuate structure 18 of FIG. 1 is positioned sufficiently distant from hitch ball 14 to allow the forward portion of socket 15 to manuever about hitch ball 14 without interference.
Arcuate surface 18 shown in FIG. 1 is suitably secured adjacent its bottom portion to plate 20C such as by welding or may be the upper portion of a single casting extending laterally from plate 20C.
Opposite end portions 18B and 18C of arcuate surface 18 are curved inwardly toward each other ending at points 62 and 62' shown in FIG. 8 to allow belt 19 of FIG. 3 to be in full contact with either curved surface when the towing vehicle is in a turned position as indicated.
Sufficient unoccupied space within arcuate surface 18 must be allowed between its ends 62 and 62' to permit coupler 15 to pivot into extreme turns without lateral interference of the arcuate surface 18. The preferred spaced apart distance between open ends 62 and 62' also shown as 63 and 63' in FIG. 9 is approximately 9 inches and not less than 4 inches nor more than 15 inches.
A preferred perimeter length of arcuate surface 18 shown in FIG. 1 beginning at open end 62 and ending at 62' shown in FIG. 8 is approximately 13 inches and not less than 6 inches nor more than 24 inches. Portion 18D of FIG. 5 arcuate surface 18 shown in FIG. 1 may be a straight surface or it may be a curved surface as shown in 18E of FIG. 8 of not less than a 2 inch radius fulcrumed from a point (not shown) passing perpendicularly through the aperture 21C. Portion 18D shown in FIG. 5 may be omitted as shown in FIG. 12.
A preferred distance between top of plate 20C and top of arcuate surface 18 is predetermined by the width of the center of belt 19 in horizontal alignment with an axis 67 of hitch ball 100 i.e. the distance from the top of plate 20C, FIG. 9, to centerline 67 plus one-half the actual belt width. Should this distance vary more than one inch above or below centerline 67, belt 19 may either tighten or loosen when manuevering the trailer through dips and over mounds. The preferred height of arcuate surface 18, FIG. 1, from top of plate 20C is not less than 1 inch nor more than 4 inches.
A pair of oppositely spaced apart brackets 38 and 38' (FIGS. 8, 9 and 10) maintain belt 19, FIG. 1, in vertical alignment with the axis of hitch ball 100, FIGS. 9 and 12, and prevent the belt from becoming disengaged from arcuate surface 18.
It should be noted that sway control device 10 shown in FIG. 2 adapted for attachment to A frame type trailer tongues such as indicated at 17, requires only structres such as eyebolts 30 mounted to each side of the trailer tongue to receive hooks 24 and 29 for connection to belt 19. However, when connection is made to a single tongue trailer 40 shown in FIGS. 11 and 13 a pair of brackets 42 and 42' are employed utilizing spaced apart apertures 43, FIG. 11, for engagement by hooks 44 for operational function of the sway control device 10D.
Mounting brackets 42 and 42' for single tongue trailers, FIG. 13, are especially constructed for simplicity of attachment. Upper portions 95 and 95' of brackets 42 and 42' are adjacent and parallel to the top of tongue 40. Lower portions 94 and 94' are parallel to upper portions 95 and 95' and extend vertically upwardly at 90 degree angles adjacent side portions of tongue 40 approximately 1 and one half inches but not less than one half inch nor more than 3 inches to upper portion of brackets 95 and 95'. At least one aperture (not shown) is provided in each of the sides of brackets 42 and 42' in alignment with each other through which bolt 71, FIG. 13, passes and through an aligned hole in tongue 40. Securing brackets to tongue 40 is simply done by tightening nut 72. The height of portions 94 and 94' is determined in relation to height of belt brackets 38 and 38', FIGS. 8 and 9, and should be parallel thereto when towing vehicle and trailer are interconnected for towing. A reinforcing strap may be extended from the upper bracket portions 95 and 95', (not shown), to lower portions 94 and 94', FIG. 13, to increase strength of brackets 42 and 42'.
FIG. 19 shows a modification of bottom portion 20C of FIG. 8, with a section containing aperture 21C removed and with a semi-circular cut out substituted therefor to partially surround the flange 101 shown in FIG. 9 of the hitch ball.
More particularly, FIG. 19 illustrates a further modification of the sway control devices shown in FIGS. 5, 6, 7, 8 and 9 wherein bottom portion 120 is provided with holes 113 and 113' for bolt on purposes to class 1 and 2 hitch brackets indicated as 11, FIGS. 2 and 12. A plate 115 is provided with spaced apart holes 114 and 114' stamped in alignment with holes 113 and 113' an aperture 126 large enough to accept the threaded shank portion of a conventional hitch ball but not its middle flanged portion 101 shown in FIG. 9. Angle brackets 116 and 116' are provided with slots 117 and 117' to adjust to the width of the class 1 or class 2 hitch bracket 11 shown in FIG. 12. Holes 119 and 119' are used in conjunction with class 1 hitch brackets with bolt 119A passing through these holes underneath the hitch bracket. Holes 118 and 118' are used with class 2 hitch bracket which are of greater thickeness than class 1 hitch bracket. Thus, bolts 112 and 112' pass through holes 113 and 113', holes 114 and 114' of plate 115 and then through elongated slots 117 and 117' and are bolted together by lock washers 121, 121' and nuts 122, 122' to form the assembly shown in FIG. 20. Bolt 119A is then placed through the desired apertures of angle brackets 116 and 116' which are then drawn tightly together against the sides of a hitch bracket by lock washer 123 and nut 124. The threaded shank portion of a hitch ball is placed through hole 126 of plate 115 and then through a similar aperture provided for class 1 and 2 hitch brackets and threadly tightened thus securing plate 115 to the hitch bracket.
Holes 127 and 127' are additionally provided in the bottom portion 120 as a convenient method for securing safety chains 128 and 128' in close proximity to the hitch coupler of a trailer vehicle and thus requiring less chain linkage and also aiding in the prevention of the hitch coupler from dropping to the roadway in event of is accidental disconnection from the towing vehicle. The chain linkage may consist of two separate short chains attached to each side of a trailer or a single chain (not shown) passing through an aperture provided for a trailer underneath the hitch coupler 16 shown in FIG. 1.
FIG. 21 illustrates a modification of bottom portion 20C of FIG. 8 wherein aperture 21C is removed and an elongated cut out section 129 is provided to surround obstructions that may be present on the top portions of some conventional equalizer heads such as moveable trigger levers 132, 132' on equalizer head 133. Each of the trigger levers function as a means to contain spaced apart spring bars mounted in or on the equalizer head which are used in conjunction with the equalizer head and attached to opposite sides of a trailer tongue to transfer some of the tongue weight of a trailer from the rear portion of a towing vehicle to the front portion of a towing vehicle thus preventing the rear portion of a towing vehicle from sagging.
Recess 125 of bottom portion 120 shown in FIG. 19 properly positions arcuate surface 110 when it is placed rearward and adjacent the flange 101 shown in FIG. 12 of a conventional hitch ball. Bottom portion 120 can then be easily welded onto the top portion of a conventional equalizer head 133 as shown in FIG. 21 that does not employ obstructions such as trigger levers 132 and 132'. Welding the sway control device disclosed to a equalizer head at the factory would constitute an improvement of the equalizer head and reduce welding and installation costs by the user.
Cut-out portion 129 of bottom portion 131 of FIGS. 21 and 22 is designed to slip over trigger levers 132 and 132' as shown in FIG. 22. This modification may also be welded to equalizer head 133 at points 134 and 134' either at the factory or by qualified welders at purchaser's option.
It should be recognized that the top portion of any conventional equalizer head may be modified to conform to arcuate surface 110' thus in effect establishing the top portion of equalizer heads such as 133, FIG. 21, to constitute a combination equalizer and sway control device.
Although but a few embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that various additional changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.
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A sway control device for mounting on a towing vehicle employing a flexible connector passing over a frictionally damping surface or surfaces for preventing uncontrolled lateral movements of the towed vehicle.
The flexible connector comprises preferably a tough, durable belt or cable having an external surface suitable for frictional damping use. A curved or arcuate structure is used in conjunction with the flexible connector for providing the friction damping surface which is positioned to encompass the common pivotal hitch connection of a towed trailer to the towing vehicle to retain and limit vertical, lateral, forward and rearward movement of the trailer coupler in event of disconnection while the trailer is being towed. Means for attachment of a safety chain linkage is incorporated into the device for additional safety when towing. Simplicity of installation, operation and interchangeability of the device is dependent on the design and utility of its component structure for proper operational functioning and for use on other trailers to be towed by the same vehicle are features of the disclosed device.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the priority of German Application No. 10 2007 035 426.8, filed Jul. 28, 2007, the disclosure of which is expressly incorporated by reference herein.
BACKGROUND OF THE INVENTION
The present invention relates to a motor vehicle, an indicating device and an operating method.
In this case the motor vehicle comprises at least one drive unit, which may be disengaged from the rest of the drive train by, for example, a suitable clutch. The object of the invention is to indicate to the driver when he is in a running state, in which the vehicle would continue to drive with the same longitudinal acceleration, even if the clutch between the drive unit and the rest of the drive train were disengaged. This running state is called “coasting” and makes possible an operating mode that saves energy by switching off the drive unit when the clutch is disengaged or by operating the drive unit at least at a reduced speed, normally idling speed.
In principle, three different drive states can be distinguished in a motor vehicle that is, accelerating, unpowered driving (“coasting”) and decelerating. It is known that coasting is the most energy efficient mode of operation, if at the same time the drive motor is disengaged from the drive train and is switched off or at least is operated at the lowest possible speed. In principle, this operating mode may be used in any conventional vehicle. In vehicles with a manually operated transmission, this operating mode is initiated by stepping on the clutch pedal and releasing the drive pedal. In vehicles with automatic transmission, this mode can be initiated by shifting into the driving position N, instead of actuating the clutch pedal. Vehicles with a hybrid drive will use this operating mode automatically, as often as possible. Yet in this context there are two problems. At any driving speed the unpowered state is a narrow range of the vehicle longitudinal acceleration—more precisely, only a single operating point, characterized by a position of the drive pedal for each engine speed. For this reason the energy saving coasting mode in the case of an automatic activation can be activated only very infrequently, if no influence is to be put on the driver's desired longitudinal acceleration.
Of course, hybrid vehicles have the possibility of covering a certain range of the longitudinal deceleration by means of the additional electric motor when the internal combustion engine is switched off. Yet, even recuperation and then use of the recuperated energy is significantly less efficient than coasting, since during coasting the kinetic energy is maintained and is reduced only by unavoidable driving resistances. However, in the case of recuperation only approximately 50% of the recuperated energy or less can be used again at a later date for accelerating. Therefore, even in the case of hybrid vehicles it is logical to use the energy efficient coasting mode as often as possible. If the driver performs the activation, there is the problem that it is difficult for him to detect this state, so that, on the one hand, he will not often use the energy saving operating mode and, on the other hand, he will activate from time to time the energy saving coasting mode only to ascertain then that the vehicle accelerates unintentionally with more or less speed than intended.
If the coasting state can be indicated to the driver, then he is in a position to induce or maintain depending on the driving situation this state by changing his manner of driving. That is, he can dispense with accelerating slightly more or less than he would have without any information about the relationships. Therefore, in the case of an automatic activation of the energy efficient coasting mode, this operating mode may be active significantly more often similarly when activated by the driver, since otherwise he would not even take the opportunity to activate without the influencing of the longitudinal dynamics.
SUMMARY OF THE INVENTION
The invention provides a dedicated indicating device for indicating the momentary drive state in order to assist the driver in using, as often as possible, the energy efficient coasting mode. In other words, the driver is offered the possibility of deciding for himself at any time the extent to which he wants to adapt his driving style in order to use the coasting mode. Thus, in the case of a hybrid vehicle the degree of deceleration and charging of the electric energy accumulator can also be specified indirectly by the driver. In this case the invention is based on the recognition that a vehicle system is often not able to use the energy efficient coasting mode, if it correctly considers the driver's inputs with respect to the vehicle longitudinal dynamics. In contrast, the driver always has a comprehensive overview of the real driving situation. Therefore, he can make a decision on the basis of what he anticipates will happen; and he can adapt his way of driving to match the driving situation and his requests. That is, since he knows the real drive state accelerating, coasting or decelerating, he can decide as a function of the driving situation whether he wants to dispense with a negligible acceleration or deceleration in order to use the energy efficient coasting mode. To this end, the dedicated indicating device is designed, according to the invention, to indicate directly to the driver, when a drive unit is not introducing an accelerating and/or decelerating torque into the drive train. This separate indication of coasting by means of a dedicated indicating device, which is provided exclusively for this function, will offer the driver optimal assistance. Thus, in this context “dedicated” has the normal dictionary definition of “set aside for special use,” namely the indication of the energy efficient coasting mode.
The indicating device is designed in such an advantageous manner that it indicates to the driver the operating ranges accelerating, free rolling (coasting) and decelerating with engine torque (of the internal combustion engine and/or optionally the electric motor). Hence, a prolonged free rolling is possible in order to achieve an optimum of energy efficiency. Therefore, with this information the driver can decide on the basis of his comprehensive overview of the real driving situation whether he wants to use the coasting mode.
An advantageous, very simple embodiment of the invention provides that the indicating device renders the three basic operating states accelerating, coasting and decelerating by means of a visual display. In the simplest case this display is a light emitting diode, which signals the state of the nonpowered drive. In this case the driver should know for optimal use of the coasting mode, when the vehicle is in the accelerating or decelerating state. That is, whether at the signal of the coasting mode he has approached the coasting state from the acceleration or deceleration range. This requires paying some attention to the visual signal.
An expansion constitutes an indicating device that can indicate at least three states in a way that can be differentiated for example, a two color light emitting diode that shows acceleration with a different color than deceleration and that extinguishes in the coasting state. Of course, it is possible to use other visual display means, with which the various drive states can be indicated or at least the coasting state can be signaled in a distinguishable manner. The basic advantage of this expansion lies in the driver's ability to recognize immediately upon looking at the indicating device the drive range, in which he currently is. Thus, he knows immediately whether he can reach the coasting state by depressing or releasing the drive pedal.
In order to render in greater detail the real drive state, the indicator may also be designed in multiple steps for example, using a plurality of light emitting diodes or continuously, for example, using a pointer instrument. As a result, the driver can be informed additionally that he is in the vicinity of the coasting state so that he may, if desired, adapt his driving even better to an energy saving way of driving.
The visual display of the real drive state can also be carried out by means of existing configurable indicating elements, such as a matrix display.
Another simple indicating device is an acoustic indicator. This type of indicator may be a simple signal tone, which indicates that the coasting state has been reached. In this case the driver should know for optimal use of the coasting operation when the vehicle is in the accelerating or decelerating state that is, at the sound of the signal tone whether he has approached the coasting state from the accelerating or decelerating range. In most driving situations this can be achieved with ease.
An expansion of the acoustic indication consists of designing this indicator in multiple steps or continuously in order to give as described above in the case of the visual display the driver more precise information about the real drive state. This can be done, for example, by varying the tone pitch or the sound.
Another preferred and very user friendly embodiment of the invention consists of using the user interface to specify the vehicle longitudinal acceleration usually the drive pedal in addition to the conventional purpose also for indicating the real drive state. To this end, the invention modifies the force-travel characteristics of the drive pedal in such a way that the driver can detect in the drive pedal that he has reached the coasting mode. This detection is achieved with a pressure point therefore, an increase in the counter-force upon moving the drive pedal forward and/or a reduction in the counter-force upon moving the drive pedal rearwards. The position of this pressure point must be variable, because it depends on the engine speed. Therefore, at different engine speeds the nonpowered state of the engine occurs at different positions of the drive pedal. Depending on the driving speed and the selected transmission ratio, the result is a respective position in the drive pedal, at which the engine neither accelerates nor decelerates.
Another type of integration into a drive pedal consists of designing the drive pedal in such a way that the coasting position is an unpowered position, and the drive pedal can be pushed from this position to the rear. The advantage of this embodiment is the possibility of the driver being able to take his foot off the drive pedal in the coasting mode even in the event of an automatic activation of the energy saving coasting mode. This can be achieved in that the hinge point of the drive pedal is not on its end or outside, but rather inside the pedal surface, so that when pressure is applied with the tip of the foot, the drive pedal is pushed forward, like a conventional drive pedal. When the foot is removed from the drive pedal, the drive pedal assumes the coasting position and from this position can be pushed rearwards by applying pressure with the heel of the foot in order to generate a braking torque, as is the case in conventional vehicles when the drive pedal is released. The range between coasting and rearmost position can be designed either without a reset force or with a reset effect in the direction of the coasting position. In the second case a snap-in device in the rearmost position ought to be provided, so that the engine decelerating effect can be maintained when changing over to the brake pedal.
In a simplified variant of this embodiment the zero torque position is always at the same point. An expanded version has the zero position as a function of the engine speed, as described above for the mono-directional drive pedal.
Instead of a drive pedal, the function can also be implemented with a hand operated operational control element for example a throttle twist grip in the case of a single track motor vehicle, a joystick-like lever or a lever of the type of a steering column switch. In this case a joystick for steering the vehicle can be designed in such a manner that it is possible to both accelerate and also to decelerate the vehicle. If the joystick is set in its neutral position and/or at a pressure point, this signifies coasting. If the joystick is pushed forward beyond the neutral position and/or the pressure point, the vehicle will be accelerated. If the joystick is pulled rearwards beyond the neutral position and/or the pressure point, the vehicle will be decelerated.
In a vehicle without a recuperation option the engine is preferably disengaged from the drive train and switched off when decelerating; and the respective deceleration is generated with the service brake. If this is not possible for technical reasons (brake load, it is necessary to run the engine because of the auxiliary units, etc.), the engine still has to be supplied with fuel between the coasting position of the drive pedal and the totally released position. In a hybrid vehicle the decelerating torque is normally generated by the generator by means of recuperation.
Described below is the operating method for conventional vehicles, which exhibit an Otto engine and which exhibit a defined allocation between the throttle flap position and the drive pedal position. In vehicles with a diesel engine or any other type of drive engine, the throttle flap is replaced by a corresponding actuator for example, the actuator of the fuel injection system. If there is no defined allocation between the drive pedal position and the throttle flap or the corresponding actuator, it is necessary to consider the resulting change in the drive pedal position.
The nonpowered state can be detected in two ways. As long as the engine is connected to the drive train, the delivered engine torque may be read by the engine control unit by way of the vehicle internal communication means, provided that such a communication exists. A small range of the positive and negative engine torque is then defined as the zero torque for signaling the coasting state.
If the zero torque cannot be read by the engine control unit, it is ascertained, according to the invention, by means of an engine characteristic graph, which shows the relationship between the drive pedal position and the engine speed when the engine is rotating freely thus, the drive pedal-speed characteristic curve, which is the result of a disengaged clutch.
In the case of an automatically activated coasting mode, this method has to be applied whenever the clutch is disengaged ( FIG. 2 ). In this case the speed n of the side of the clutch that faces away from the engine is determined from the driving speed and the real transmission ratio. From this speed n a throttle flap position and/or a drive pedal position s s for the zero torque is clearly derived from the drive pedal-speed characteristic curve. If this position of the drive pedal is taken, then the coasting mode is indicated to the driver by means of one of the above described methods.
If the driver activates the coasting mode, for example, by opening the clutch and releasing the drive pedal, the coasting mode is always indicated irrespective of any other drive state and engine speed, as long as the driver does not leave this coasting mode again, for example, by closing the clutch.
In order to avoid in the event of an automatic activation of the coasting mode that the internal combustion engine is switched off too often and then re-started again after a short period of time, both a switch-off dead time for the activation of the coasting mode and a hysteresis Δs for the drive pedal position ( FIG. 2A ) are provided. In other words, instead of the zero torque position, a zero torque range of the drive pedal position is provided, which the driver has to observe for a defined period of time (switch-off dead time) by activating the drive pedal, so that a switch over to the coasting mode occurs. As an alternative or in addition, the limits of the zero torque range may be signaled to the driver as additional pressure points, which may be easier to overcome than the zero torque position. Thus, it is ensured that a random minor change in the drive pedal position cannot induce the engine to re-start.
It is possible to provide in an advantageous manner a switch-off dead time operational control element, with which the driver can set any desired switch-off dead time. It is also advantageous to provide an additional drive pedal hysteresis operational control element, with which the driver can set the drive pedal hysteresis.
The switch-off dead time operational control element and the drive pedal operational control element may also be combined in an advantageous manner. Then the result is an operational control element for the coasting indicating device, with which the degree of usage of the coasting mode can be adjusted to the individual case. Hence, this coasting operational control element exhibits two end positions. In the one end position the internal combustion engine is already switched off, when the drive pedal is in the zero torque position and/or in a wide range about this position for only a short period of time. In the other end position the system is totally switched off. Therefore, coasting is neither signaled nor automatically activated. This operational control element may exhibit an obvious pressure/locking point in order to signal even in a haptic manner to the driver the intended switch-off operation.
Of course, the adaptation of the switch-off dead time and hysteresis as well as other characteristic values, which describe the operational control characteristics and the indicating concept, may be provided not only with the aid of the coasting user interface, but also with any suitable user interface of the invention. Characteristic values may be presented to the driver or can be adjusted for the driver by the on-board computer.
In the case of a hybrid vehicle the indication by means of a haptic drive pedal makes it possible to expand the recuperation capability in that in the rear-most position of the drive pedal a vehicle deceleration is specified that is greater than that corresponding to the respective overrun torque of the engine. In the known operational control concepts for hybrid vehicles the reverse path is taken in order to improve the degree of the accelerating effect. That is, in the normal position of the selector lever of the automatic transmission the rearmost position of the drive pedal corresponds to a very slight deceleration, close to the position of the coasting mode, in order to use often operating states that are at least close to coasting. If the deceleration effect is desired, then a manual shift into another mode of the automatic transmission can be executed. In addition to the expanded use of recuperation, the strategy that is described here also achieves added comfort and convenience, because the driver does not have to change-over so often from the drive pedal to the brake pedal in order to achieve a somewhat higher deceleration.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic drawing of preferred embodiments of the present invention.
FIG. 2 is a schematic drawing of the hysteresis and the switch-off dead time for activating the coasting mode in accordance with embodiments of the present invention.
FIG. 3 is a schematic drawing of a visual indicator in accordance with the invention.
DETAILED DESCRIPTION
FIG. 1 is a schematic drawing of the haptic indication with the use of the user interface drive pedal. The drawings 1 B and 1 C show the embodiments of a haptic drive pedal. The rotational point of the drive pedal is illustrated by the small circles in FIG. 1 . In the embodiments of the haptic drive pedal the conventional drive pedal is expanded in such a manner that a corresponding activation by, for example, an actuator, can signal to the driver the pedal positions, determined by the algorithm, in the form of a pressure point.
FIG. 1A shows a conventional drive pedal. The non-activated position that is, the position in which no force is applied corresponds to a deceleration with the drive unit.
FIG. 1B shows a drive pedal with a pressure point. In this case the non-activated position that is, the position in which no force is applied and which corresponds to coasting (the marked position) signifies a deceleration as a function of the braking torque of the drive unit.
FIG. 1C shows a bi-directional haptic drive pedal. The rotational point in the bi-directional haptic drive pedal is not on one end as in the case of the conventional drive pedal, but rather is shifted to its center.
All three embodiments, according to FIGS. 1A to 1C , are activated by the driver applying the ball of the foot in the direction of the arrow. In addition, the bi-directional haptic drive pedal, which may be activated by the driver applying his foot, may also be activated by the heel in the opposite direction (see the dotted line in FIG. 1C ). If a braking torque (for example, by using an electric motor as a generator or by means of a service brake) is to be exerted on the drive train in order to decelerate the vehicle, the bi-directional haptic drive pedal is pushed rearwards by applying pressure with the heel.
In both drawings of FIGS. 1B and 1C the result is a pedal position, with which the coasting mode is associated. If this pedal position is taken by the driver's foot, the drive train does not transfer a drive torque called the zero torque position, which corresponds to a drive state, in which the internal combustion engine neither accelerates nor decelerates the vehicle. In this drive state it is irrelevant whether the clutch is closed or open, because it does not affect the vehicle acceleration. For energy efficiency reasons, however, the clutch is open and the internal combustion engine is switched off for functions that relate to the coasting mode. Electric drive motors are also operated in the most energy saving state. This special, coasting-related function is also discussed below. FIG. 3 illustrates an optional way to convey to the driver the information that is conveyed in FIG. 1B . More particularly, the relationship between the driver's foot position on the accelerator pedal and the pedal position with which the coasting mode is associated is part of a visual display in FIG. 3 . An advantageous, very simple embodiment of the invention provides that the indicating device renders the three basic operating states accelerating, coasting and decelerating as shown respectively by the right, center and left lines in the visual display of FIG. 3 . In the simplest case this display is a light emitting diode, which signals the state of the nonpowered drive. In this case the driver should know for optimal use of the coasting mode, when the vehicle is in the accelerating or decelerating state. That is, whether at the signal of the coasting mode he has approached the coasting state (center line) from the acceleration or deceleration range. This requires paying some attention to the visual signal. An expansion constitutes an indicating device that can indicate at least three states in a way that can be differentiated for example, a two color light emitting diode that shows acceleration with a different color than deceleration and that extinguishes in the coasting state. Of course, it is possible to use other visual display means, with which the various drive states can be indicated or at least the coasting state can be signaled in a distinguishable manner. The basic advantage of this expansion lies in the driver's ability to recognize immediately upon looking at the indicating device the drive range, in which he currently is. Thus, he knows immediately whether he can reach the coasting state by depressing or releasing the drive pedal. In order to render in greater detail the real drive state, the indicator may also be designed in multiple steps for example, using a plurality of light emitting diodes or continuously, for example, using a pointer instrument. As a result, the driver can be informed additionally that he is in the vicinity of the coasting state so that he may, if desired, adapt his driving even better to an energy saving way of driving.
The advantageous feature with respect to the usage of this user interface for the purpose of indicating the coasting state is that the vehicle responds to the driver's input in the same way that he is accustomed from conventional vehicles, and that the driver may specify the desired coasting by merely using such operational control elements that are familiar to him. The only difference is that a haptic feedback signals to him that position of the drive pedal, in which the coasting related functions can be activated, by, for example, uncoupling and switching off the internal combustion engine without affecting the vehicle longitudinal dynamics. The result of the automatic activation of the coasting mode is that this mode is activated whenever it has no effect on the vehicle longitudinal dynamics. The signaling of this state to the driver enables him to adapt his driving in such a manner that coasting is used even in such driving situations that require only a slight adaptation in the driver's way of driving. Thus, an optimal and maximum use of the coasting mode and the coasting related functions is achieved.
In order to avoid that the internal combustion engine is switched off too often and then is re-started again after a short period of time, the drive pedal position is provided with a hysteresis and a switch-off dead time for activating the coasting mode, as shown in FIG. 2A . The two lines in the left diagram symbolize the forward direction (push inwards, upper line) and the rearwards direction (release, bottom line) of the drive pedal activation. In other words, there is, instead of the zero torque position s s (n), a zero torque range of the drive pedal position, which the driver has to maintain for a certain period of time by activating the drive pedal, so that there is a change-over into the coasting mode. This zero torque range is shown with the shaded area in FIG. 2A . As an alternative or in addition, the limits of the zero torque range may be signaled to the driver as additional pressure points, which may be easier to overcome than the zero torque position. Thus, it is ensured that a random minor change in the drive pedal position cannot induce, for example, the engine to re-start.
In FIG. 2A there are not only the two solid graduated lines but also various dashed lines, where the force stage ΔF is located at various drive pedal positions s. This symbolizes the change in the position s s as a function of the zero torque speed, as follows from the diagram in FIG. 2B . Of course, all positions between the drawn positions are possible that is, all positions which follow from FIG. 2B .
In FIG. 2B not only the solid characteristic curves, but also two dotted lines are drawn. They symbolize a change in the characteristic curve owing to the various engine temperatures or other influencing parameters.
In addition, a switch-off dead time operational control element and/or a drive pedal hysteresis operational control element for the coasting indicating interface may also be provided. Then the result is a coasting user interface, with which the coasting related functions and thus, the coasting readiness of the driver can be adapted to the individual case. For example, this coasting user interface exhibits two end positions. In the one end position the internal combustion engine is already switched off, when the drive pedal is in the zero torque position and/or in a wide range about this position for only a short period of time (Δs large and switch-off dead time small). In the other end position the system is totally switched off. This means in FIG. 2A , for example, ΔF=0 and Δs=0 and very long switch-off dead time. Therefore, the operational control elements for the switch-off dead time and the drive pedal hysteresis may exhibit an obvious pressure/locking point in order to signal even in a haptic manner to the driver the complete switch off.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
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An indicating device for a motor vehicle and an operating method are provided. The motor vehicle includes a drive train with at least one drive unit. The indicating device shows in a differentiable manner to the driver the drive states of accelerating, unpowered driving (coasting) and decelerating using the drive train, and at a minimum signals to the driver when the coasting state exists so as to permit the driver to optimize efficient use of the vehicle.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No. 11/098,330, filed Apr. 4, 2005 (which matured into U.S. Pat. No. 7,487,618), which claims the benefit of U.S. Provisional Application No. 60/559,285, filed Apr. 5, 2004. The disclosure of prior U.S. application Ser. No. 11/098,330 is incorporated herein by reference.
SEQUENCE LISTING
Non-Applicable.
BACKGROUND
1. Field of Invention
This invention relates to an aerodynamic means that mitigate wind generated vortices and uplift loads on the roof perimeter area of a building, in a simple, effective, and economical way, applicable for both new constructions and retrofits of existing buildings.
2. Discussion of Prior Art
The previous and present roof construction practices normally lead to a roof perimeter configuration that tends to generate edge vortex and subjects the roof perimeter area to severe uplift and high risk of wind damage. Structural methods have been used to mitigate the risk of wind damage. For example, builders may use stronger fasteners or smaller fastener spacing for roof cover and deck in the roof edge and corner area, and use “hurricane straps” in lieu of toenails to tie down the roof framing to the wall structure. Some aerodynamic methods have been recommended, such as those disclosed in U.S. Pat. Nos. 6,601,348 of Banks et al. (2003), 4,005,557 of Kramer et al. (1977), and 5,918,423 of Ponder (1999). Banks et al. described various types of wind spoilers raised above the roof plane that function to mitigate edge vortex formation; however, the exposed structure is rather complicated, and is susceptible to wind damage itself because the raised structure subjects itself to accelerated airflow across the roof edge. Kramer et al.'s conceptions are essentially an earlier version of roof wind spoiler system that bears similar features to Banks et al. but its limited breadth impedes its effectiveness. Ponder disclosed a wind spoiler ridge cap that is specifically designed for protecting pitched gable roof ridges, while this present invention primarily deals with roof perimeter edges.
In U.S. Pat. No. 6,606,828 of this applicant et al., a series of roof edge configurations are recommended for use to mitigate vortex and high uplift in the roof perimeter areas, which are more suitable for flat and low-slope roofs that are often constructed with single ply membrane or built-up roofing. The present invention discloses roof edge configurations that are chiefly designed for deeper slope roofs that are often constructed with asphalt shingles, roof tiles and metal panels etc, and normally presented with different details at the roof perimeter.
SUMMARY OF THE INVENTION
This invention discloses an aerodynamic means that mitigate wind generated vortices and uplift loads on the roof perimeter area of a building, in a simple, effective, and economical way, applicable for both new constructions and retrofits of existing buildings. This is achieved by using a roof edge guard of an aerodynamic cross-sectional shape, attached to the outer side of the roof perimeter edge, as exemplified hereafter in the description section. The roof edge guard is generally installed alongside a roof edge, and mounted onto an existing fascia or bargeboard. As an option most appropriate for new constructions, it can also be mounted directly onto a roof frame member in place of fascias or bargeboard. The configuration modifies the cross-sectional shape of otherwise abrupt roof edges that tend to generate strong vortex during high winds. This invention is primarily applicable for gable, gambrel, mono-slope and overhung flat roof edges where there is no significant rainwater runoff. It is also applicable for roof edges where there is rainwater runoff but no draining devices such as a gutter system being installed, for example, the eaves of gable and hip roofs without gutters being attached thereon.
OBJECTS AND ADVANTAGES
Accordingly, several objects and advantages of the present invention are:
to provide roof edge configurations which reduce wind loads on the roof edge details;
to provide roof edge configurations which reduce wind loads on roofing materials, roof decks and framing in the roof perimeter areas;
to provide roof edge configurations which reduce wind uplift loads generally on a building structure that are transferred from the roof;
to provide roof edge configurations which reduce vortex scouring of roofing materials, such as asphalt shingles, roofing tiles, paver etc, and prevent them from becoming wind-borne missiles injuring people and damaging adjacent building envelopes during severe wind events;
to provide roof edge configurations which stabilize wind flow over the roof and minimize cyclic loads on roof components resulting from recurring winds, reducing the chances of damage due to material fatigues;
to provide roof edge configurations which prevent rainwater from being driven sideward and upward by wind turbulence and pressed through the gaps between roofing material and roof deck, and into the inner space of the roof assembly, during wind/rain events;
to provide roof edge configurations which possess the desired aerodynamic performance while maintaining an aesthetic and waterproofing functionality under both extreme and recurring weather conditions.
Further objects or advantages are to provide roof edge configurations which add an important function to a roof edge system, and which are still among the simplest, inexpensive to manufacture and convenient to install. These and still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A schematically illustrates the cross-sectional view of one of the preferred basic configurations formed with sheet material, as being installed on an overhung gable roof edge as an example.
FIG. 1B shows a similar exterior configuration as being installed on a non-overhung gable roof edge as an example.
FIG. 2 illustrates a similar exterior configuration formed with solid material as an option.
FIGS. 3 , 4 and 5 exemplify exterior shapes that have little compromises in functionality while providing alternative appearances for aesthetic purposes.
FIG. 6 illustrates an example to showcase the recommended installation option for situations where roof covering is wrapped downward around the roof deck edge, as often seen for metal roofing.
FIG. 7 demonstrates the usage of an example roof edge guard according to this invention for eave edges where no gutter system is used.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1A through 1C illustrate one of the preferred basic configurations of the present A roof edge guard is generally an elongated assembly and is disposed longitudinally in parallel with a roof edge. FIG. 1A shows a cross-section view for one of the preferred configurations of the present invention, a roof edge guard 110 being installed on a gable-end overhang 10 of a roof structure. A typical roof overhang is a portion of a roof structure that is supported by and hangs over a wall 20 of a building, and extends substantially outwards beyond the outer wall surface 21 . The gable-end overhang 10 and associated components 11 , 12 , 13 , 14 , 15 , and 16 , as well as trim members 31 and 32 , are not part of this invention themselves, but are included here to illustrate their relationship with the edge guard 110 that is the subject matter of this invention. Some gable roofs do not have a gable-end overhang, as exemplified in FIG. 1B , or do not have one as shown, nevertheless the spirit of the present invention holds wherever the herein-described aerodynamic roof edge guard may be installed properly on the gable edge of a roof. Moreover, although many of the examples in this application are illustrated for gable edges, the present invention is applicable on other types of roof edges, particularly for roof edges where there is no significant rainwater runoff. Examples of such roof edges include gable, gambrel, mono-slope (so-called lean-to), and overhung flat roof edges. For roof edges where there will be certain rainwater runoff, such as the eaves of various roof types including gable and hip roofs, this invention is also applicable if no water draining devices such as gutters are being used therein, as described later in this application.
The roof edge guard 110 , exemplified here as made of sheet material, consists of an upper face portion 111 , an intermediate face portion 112 , and a lower face portion 113 . The upper face portion 111 , disposed in close proximity to the outer edge 17 of the roof covering 11 and positioned flush, or at a reasonable angle within ±55°, with the plane of the roof covering 11 , facilitates a smooth wind flow across the roof edge, minimizing flow separation therein. Minor upward deviation or tolerance at installation is permissible for such roof edges where there is no significant rainwater runoff, to the extent that the upward deviation is not expected to cause debris clogging and accumulation along the roof edge. The lower face portion 113 is disposed with its edge above or in vicinity to the lower end of the bargeboard 14 , or onto the wall surface below the bargeboard as shown in FIG. 1B for non-overhung roof edges, and extends generally outwardly while also upwardly in this example. The intermediate face portion 112 , having one or more straight or curved segments, connects the lower and upper face portions in such a way that slope change across a junction between any adjacent two of the face portions, or of segments therein, is generally within ±55°. A gradual slope change minimizes the chances of wind flow separation and vortex formation. Notwithstanding with this general or global slope change limit, corrugated segment or segments, or small step or steps on the outer face of a roof edge guard, can be used within, or in lieu of, the face portions without compromising its functionality. Local slope change exceeding ±55° within the segment of corrugation or steps is permissible as long as the depth of the corrugation or the riser size of the step is sufficiently small and does not increase the chances of major flow separation.
The roof edge guard 110 may be mounted on to the roof edge with any appropriate means that can ensure the configurations of the outer face of the roof edge guard as described in detail herein and defined by the accompanied claims. An exemplary mounting method is described here merely to showcase a relatively simple method that uses anchor bars 120 and fasteners 130 , for an aerodynamic roof edge guard 110 made from resilient sheet material. In FIG. 1A , and similarly in FIG. 1B , an anchor bar 120 is secured to the bargeboard 14 with a plurality of fasteners. The roof edge guard 110 is then snapped on to the anchor bar 120 . This is done by hooking the edge guard's top bend 114 on the anchor bar's top bend 124 and pressing the edge guard downwards and inwards until the edge guard's bottom bend 115 clicked into the anchor bar's bottom bend 125 . A spring clip 140 provides additional support for the edge guard 110 . Small amount of rainwater may slip through the gap between the top bend 114 of the edge guard and the protruding portion 17 of the roof covering. A V-shape 128 on the upper part of the anchor bar forms a channel to catch and guide this small amount of water down the slope along the gable edge, prevent it from wetting the normally wooden components 31 and 14 , and drain it off where the anchor bar terminates. Along the length of the gable edge, either multiple discrete anchor bars 120 , or continuous cleats of such similar cross-sectional shapes, can be used for sloped roof edges.
In fact, any other suitable mechanisms of similar functions may be used for mounting the roof edge guard 110 onto a roof edge.
Very limited amount of rainwater or moisture may also slip into the inside chamber of the edge guard 110 . Practically, since a roof edge guard mounted on a gable edge is sloped down along the gable edge, water inside the edge guard 110 can drain out through its lower end. For roof edges that are horizontal or with a low slope, a plurality of drain holes 116 can be drilled along the bottom edge of the edge guard 110 providing a means for draining and venting of condensation water or residual rainwater inside the edge guard's chamber. Similar optional drain holes (not shown) can also be used on the lower edge of the channel 128 for a continuous mounting cleat.
The aerodynamic roof edge guard 110 has at least three functions. The first is to minimize the extent of flow separation and the strength of associated vortices over a roof edge, or to completely eliminate them for some approach wind directions. These effects tend to be more pronounced for higher wind speeds as desired. High uplifts and strong scouring that result from wind-induced edge vortices above the roof, are prime causes for wind damage to roof components. Secondly, it shields the underside of the protruding portion 17 of the roof covering 11 , such as an array of shingles, shakes, or metal panels, from upward flow and pressure that tend to peel the roof covering 11 upwards and away from other parts of the roof edge assembly 10 . The third function is to prevent upward flow-driven rain from being pressured to infiltrate into the roof structure through the unsealed gaps between the roof covering 11 and the trim member 31 .
For roof edges without overhang, as illustrated in FIG. 1B , a roof edge guard 110 b can be mounted with the bottom bend 115 b attached directly to the wall surface 21 b or any vertical or nearly vertical surface therein. For applications on existing buildings, this optional method can be used only if the wall siding or surface material thereof is suitable for mounting; otherwise, mounting the edge guard 110 b onto a fascia or bargeboard 14 b , similar to the method illustrated in FIG. 1A , is recommended.
An aerodynamic roof edge guard can also be made from solid materials, such as solid wood, or any other suitable materials, and be mounted on a roof edge with any applicable means, so long as the aerodynamic shapes of the outer face portions are maintained. FIG. 2 exemplifies an aerodynamic roof edge guard 210 made from solid wood material as being mounted on a gable-end overhang 10 , where the outer face portions 211 , 212 and 213 are equivalent to the face portions 111 , 112 and 113 in FIG. 1A .
Some other embodiments of this invention are illustrated in FIGS. 3 through 7 . FIG. 3 shows an edge guard 310 shaped primarily with a semi-circle or semi-ellipse, where the outer face portions 311 , 312 and 313 are equivalent to the face portions 111 , 112 and 113 in FIG. 1A . It should be noted that this configuration is not a preferred one for roof edges with no overhang since strong upward flow along the wall surface would exert significant pressure on the underside of the lower face portion 313 given its nearly horizontal layout. Such high pressure would have several undesired effects. The first is to increase the upward load on the edge guard 310 . Secondly, this high pressure would transmit into the inside chamber of the edge guard 310 through the unsealed gap between the edge guard bottom bend 315 and the wall surface, and thus increase the outward load on the edge guard. If discrete anchor bars are used along the roof edge for mounting, the residual of this high pressure could also reach and exert on the underside of the protruding portion 17 of roof covering 11 . The third undesired effect would be the potential pressure-driven infiltration of residual rainwater or moisture from the pressurized inside chamber of the edge guard 310 into the roof edge assembly, to which the edge guard 310 would have been attached. In addition, this configuration will conceivably yield higher outward negative pressures on the outer face of the edge guard 310 for such a direct wall contact application. Hence, for roof edges without overhang, configurations such as one depicted in FIG. 1B are recommended.
For aesthetic considerations, certain modifications to the profile shape of the outer face of a roof edge guard are allowable. For example, the lower face portion of a roof edge guard can be shaped to match or to approximate the shape of some of the roof edge gutters that may be common in a geographic region or prevailing for a specific roof edge system maker. FIG. 4 shows an example of such modifications, where the outer face portions 411 , 412 and 413 are equivalent to the face portions 111 , 112 and 113 in FIG. 1A . Other modified profiles are also possible; however, such modified profiles should only contain steps, if any, that have a riser size 417 less than 25% of the total height 418 of the edge guard. Again, for roof edges without overhang or other direct wall contact applications, the slope of the lower face portion 413 should be steeper where it contacts or approaches the wall surface 21 .
Configurations primarily comprising of plane surfaces can also be utilized. FIG. 5 shows an example of such alternative configurations, where the outer face portions 511 , 512 and 513 are equivalent to the face portions 111 , 112 and 113 in FIG. 1A .
FIG. 6 provides an example for an edge guard 610 being installed on a roof edge that has the roof covering 18 wrapped downwards, most often seen with metal roof coverings, such as metal tiles, metal shakes and metal panels, as well as clay tiles in some instances.
FIG. 7 illustrates a roof edge guard 710 being used on an eave edge of a sloped roof where a draining device such as a gutter system is not being used. For this application, the upper arris 717 of the roof edge guard cover 710 is also disposed in close proximity to, but slightly lower than, the protruding edge 77 of the roof covering 71 . An outwardly and downwardly extending upper face portion 711 is also preferred to allow rainwater shed off from the roof to continue run over, and eventually be shed off from, the roof edge guard 710 . Discrete anchor bars 120 , instead of continuous cleat, mounted along the eave edge, are preferred for this application. This is to prevent runoff rainwater, of which a limited amount can slip through the gap between the edge guard upper arris 717 and the roof covering outer edge 77 , from being built up in the V-shaped channel 128 .
Installation and Operation
An embodiment of this invention is a passive flow control device or design for building roof edges. Once installed properly, it stays functioning in such a way that it mitigates vortex formation at a roof edge and reduces uplifts and roof vortex scouring, whenever the wind blows towards a building bearing atop such roof edge devices or designs, and requires no active operational intervention.
Conclusion, Ramifications, and Scope
It is apparent that roof edge guards of this invention provide aerodynamically advantageous devices or designs for mitigating roof edge vortex and roof uplift, and are still among the simplest, most inexpensive to manufacture and convenient to install.
Although the description above contains many specifications, 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. Various changes, modifications, variations can be made therein without departing from the spirit of the invention. Roof edge guards can be made of any reasonably durable material with any appropriate means of fabrication as long as a configuration according to the spirit of this invention is accomplished to support the described working mechanism and to provide the associated functionality. Various surface portions of a roof edge guard may also bear such surface details as corrugation or steps of adequate sizes, as opposed to perfectly smooth surfaces. Any appropriate conventional or new mounting method can be used to secure a roof edge guard to a roof perimeter without departing from the spirit of this invention. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.
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An aerodynamic system attached to the outer side of the roof perimeter edge to mitigate wind generated vortices and uplift loads on the roof perimeter area of a building, applicable for both new constructions and retrofits of existing buildings. A roof edge guard is generally installed alongside a roof edge, and mounted onto an existing fascia or bargeboard. As an option most appropriate for new constructions, it can also be mounted directly onto a roof frame member in place of fascias or bargeboard. The configuration modifies the cross-sectional shape of otherwise abrupt roof edges that tend to generate strong vortex during high winds.
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FIELD OF THE INVENTION
[0001] The present invention relates to the field of allergy. More specifically, the invention relates to the identification of novel allergens from mammals and to diagnosis and treatment of allergy towards mammals.
BACKGROUND
[0002] Dog dander is a common cause of indoor allergy with symptoms including rhinitis, conjunctivitis, bronchial inflammation and asthma. Dog allergens can be detected not only in houses where dogs are kept as pets but also in other places such as schools and day care centres where dogs are not present on a regular basis (1).
[0003] Allergy to dog is accompanied and dependent of sensitization to proteins released from dog hairs and dander. In cases of suspected allergy to dog, the clinical investigation includes assessment of sensitization by skin prick or specific IgE antibody measurement using extract of dog hair and/or dander. A laboratory immunoassay for specific IgE, such as a Phadia ImmunoCAP, can detect most cases of sensitization to dog using natural dog dander extract due to favourable assay conditions and a large solid phase available for allergen attachment.
[0004] Dog hair and dander extracts contain a complexity of allergenic and non-allergenic proteins (2, 3). Three dog allergens have so far been identified and studied in detail: Can f 1, Can f 2 and Can f 3. Can f 1, a member of the lipocalin protein family, with reported molecular weight of 21-25 kD, was first purified by de Groot et al. (4) and later cloned and expressed as a recombinant protein (5). Can f 2 belongs to the same protein family but is a protein distinct from Can f 1 (4, 5). Can f 3, dog serum albumin, is a relatively conserved protein demonstrating extensive cross-reactivity to other mammalian albumins (6).
[0005] Of the known dog allergens, Can f 1 is the most important, binding IgE antibodies from approximately half of dog allergic subjects (7). About 20% of dog allergic subjects display IgE binding to Can f 2 but most of these are also sensitized to Can f 1. Although 30-40% of adult dog allergic individuals may show IgE binding to Can f 3 (2, 8), the specific clinical relevance of mammalian serum albumins is uncertain.
[0006] It has been known for a long time that major allergens relevant to allergy to rodents, such as mice and rats, are present in the animals' urine and these have been isolated and extensively characterized (9-13). IgE antibody binding activity has also been reported to exist in urine of other animals, including cats and dogs (14), but no allergen has been purified from urine of these animals and characterized at a molecular level.
SUMMARY OF THE INVENTION
[0007] As stated above, a laboratory immunoassay for specific IgE can detect most cases of sensitization to dog using natural dog dander extract due to favourable assay conditions and a large solid phase available for allergen attachment. However, in a miniaturized or non-laboratory immunoassay, such as an allergen microarray or a doctor's office test, the combination of less favourable assay conditions, lower capacity for antibody-binding allergen reagent and natural allergen extract of limited potency, has been found to cause insufficient diagnostic sensitivity. A similar situation may exist also for immunoassays for specific IgE to other animal epithelia. Thus, there is a need in some cases to use pure allergenic proteins to achieve sufficient sensitivity in diagnostic tests for specific IgE.
[0008] Furthermore, a significant proportion of dog allergic individuals also do not react to any of the known identified dog allergens and this was recently demonstrated in a Finnish population (7).
[0009] The above led the present inventors to look for additional, not yet identified, dog allergens. Such novel allergens may be useful not only as reagents for increased sensitivity in routine diagnostic tests, but also as a complement to known dog allergens in different types of component-resolved diagnostic applications (15, 16). Pure allergenic proteins, or fragments and variants thereof with improved non-anaphylactic properties, may also be used in component-resolved immunotherapy (16-20).
[0010] A new major allergen has thus been purified from dog urine and identified as prostatic kallikrein. It is in all aspects distinct from previously known dog allergens. Further, a similar or identical and immunologically equivalent allergen has been found to exist in dog dander extract. Kallikrein represents an important addition to the panel of known dog allergens and will be useful in the diagnosis of dog allergy. It is also anticipated that homologous proteins from other mammals, such as cat, horse and rodents, including rat and mouse, will have similar allergenic properties and diagnostic utility.
[0011] Prostatic kallikrein was found to exist not only in urine but also in the fur of dander of dogs. However, the fact that protein specifically expressed in prostate tissue would be restricted to male individuals, suggests that female dogs would lack this allergen. Preliminary results in our laboratory indeed support this notion and, if corroborated by results from more extensive studies, the implication would be that dog allergic individuals sensitized exclusively to prostatic kallikrein may tolerate female dogs.
[0012] In a recently published report, it was demonstrated that vaginal hypersensitivity reaction to ejaculate was associated with IgE sensitization to human prostate-specific antigen, PSA, present in seminal plasma (21). As canine and human prostatic kallikrein and human prostate-specific antigen have partial sequence similarity, it is possible that sensitization to canine prostate-specific kallikrein confers an elevated risk of developing such allergic reactions. It can also be envisaged that IgE-mediated immune reactions to prostate-specific kallikrein may play a role in certain cases of infertility in humans.
[0013] In one aspect the invention relates to the use of kallikrein in diagnosis of Type I allergy and the use of kallikrein for the manufacture of a composition for diagnosis of Type I allergy.
[0014] In a further aspect the invention relates to an allergen composition “spiked” with kallikrein. Such an allergen composition may be an allergen extract or a mixture of purified or recombinant allergen components having no or a low kallikrein content, wherein the kallikrein is added in order to bind IgE from patients whose IgE would not bind or bind poorly to the other allergen components in the composition. This aspect of the invention also relates to a method for producing such a composition, which method comprises the step of adding kallikrein to an allergen composition, such as an allergen extract (optionally spiked with other components) or a mixture of purified native or recombinant allergen components.
[0015] In yet a further aspect the invention relates to an in vitro diagnostic method for diagnosing a Type I allergy in a patient, wherein a body fluid sample such as a blood or serum sample from the patient is brought into contact with kallikrein or a composition according to the previous aspect, and it is detected whether or not the patient sample contain IgE antibodies that bind specifically to kallikrein. Such a diagnostic method may be carried out in any manner known in the art. The kallikrein may e.g. be immobilized on a solid support, such as in a conventional laboratory immunoassay, in a microarray or in a lateral flow assay.
[0016] In a further aspect the invention relates to a diagnostic kit for performing the method according to the previous aspect, which kit includes kallikrein.
[0017] In the above mentioned aspects, the wildtype kallikrein molecule may be replaced with fragments or variants of kallikrein, natural or man-made, sharing epitopes for antibodies with wildtype kallikrein, as defined below.
[0018] The invention further relates to a method of treatment of Type I allergy comprising administering to a patient in need of such treatment a kallikrein or a modified kallikrein, as explained below. This aspect of the invention also relates to the use of kallikrein in such immunotherapy, including e.g. component-resolved immunotherapy (16). In one embodiment of this aspect, the kallikrein may be used in its natural form or in a recombinant form displaying biochemical and immunological properties similar to those of the natural molecule. In another embodiment, kallikrein may be used in a modified form, generated chemically or genetically, in order to abrogate or attenuate its IgE antibody binding capacity, while preferably being capable of eliciting an IgG response in a treated individual. Examples of modifications include, but are not limited to, fragmentation, truncation or tandemerization of the molecule, deletion of internal segment(s), substitution of amino acid residue(s), domain rearrangement, or disruption at least in part of the tertiary structure by disruption of disulfide bridges or it's binding to another macromolecular structure, or by removal of the protein's ability to bind calcium ions or other low molecular weight compounds. In yet another embodiment of this aspect, the individual 10 kDa and/or the 18 kDa subunits of kallikrein, which display reduced IgE binding activity as compared to the intact molecule, are used as modified kallikrein.
[0019] In all of the above mentioned aspects of the invention, the kallikrein can be derived from any mammal producing kallikrein capable of inducing an allergic response in a patient. The kallikrein may be purified from its natural source, such as from urine, saliva or other body fluids, or from tissue, such as hair or dander, of the mammal in question. It may also be produced by recombinant DNA technology or chemically synthesized by methods known to a person skilled in the art.
[0020] The invention also relates to canine prostatic kallikrein for use in diagnosis and therapy, such as diagnosis and therapy of Type I allergy to dog.
[0021] The invention also relates to a method for purification of kallikrein from mammalian urine, comprising the steps
filtering the mammalian urine; buffer exchange with a buffer suitable for hydrophobic interaction chromatography; filtering of the buffer exchanged urine sample; applying the buffer exchanged urine sample to a hydrophobic interaction chromatography column; and collecting the flow-through fraction comprising kallikrein.
[0027] The mammalian urine may be canine urine.
DEFINITIONS
[0028] Kallikreins are proteolytic enzymes from the serine endopeptidase family found in normal blood and urine. In the IUBMB enzyme nomenclature system, plasma kallikrein has been assigned number EC 3.4.21.34 and tissue kallikrein number EC 3.4.21.35. Urinary kallikrein from dog is a 28 kDa heterodimeric protein comprising two subunits of approximately 10±2 and 18±2 kDa, respectively, for the purposes of this invention referred to as the 10 and 18 kDa subunits, respectively. It has an amino acid sequence according to SEQ ID NO: 1, GenBank Accession no: P09582, and homologous proteins have been described in a wide range of mammalian species, including, horse, cow, pig, mouse, rat and primates (e.g. Accession no AAQ23713-4 (horse), NP — 001008416 (cow), P00752 (pig), P00755-6 and P15947 (mouse), P36373 and P00758 (rat), Q28773 (baboon), XP — 001174026 (chimpanzee), Q07276 (macaque), P20151, Q07276 and AAM11874 (human).
[0029] Variants and fragments of a kallikrein should be construed as meaning proteins or peptides with a length of at least 10 amino acids, more preferably at least 50, even more preferably at least 75 or 100 amino acid residues, and a sequence identity to said kallikrein of at least 50%, preferably over 60%, 70%, 80%, 90% or 95%.
[0030] A modified kallikrein should in the context of the present invention be construed as meaning a kallikrein that has been chemically or genetically modified to change its immunological properties, e.g. as exemplified above in relation to the immunotherapy aspect of the invention.
[0031] Variants and fragments of kallikrein sharing epitopes for antibodies with wildtype kallikrein should be construed as being those fragments and variants whose binding of IgE antibodies from a serum sample from a representative kallikrein sensitized patient can be significantly inhibited by kallikrein. Such an inhibition assay may e.g. be performed according to the protocol disclosed in Example 8.
[0032] A hypoallergenic modified kallikrein or variant or fragment of kallikrein should be construed as being a modified kallikrein or variant or fragment of kallikrein that is not capable of binding kallikrein reactive IgE antibodies from a serum sample of a representative kallikrein sensitized patient, as determined e.g. by the protocol according to Example 3 or which displays no or significantly reduced biological allergen activity, as determined by a cellular activation assay such as the basophil histamine release assay (22, 23).
BRIEF DESCRIPTION OF DRAWINGS
[0033] FIG. 1 shows the fractionation of dog urinary proteins by size exclusion chromatography. Fractions comprising each of the three peaks indicated in the figure (labeled 1-3) were pooled as indicated for analysis of IgE binding activity.
[0034] FIG. 2 shows the purification of an IgE binding protein from peak 2 of FIG. 1 by reversed phase chromatography. The peak containing the protein selected for further investigation is indicated by an arrow.
[0035] FIG. 3 is an SDS-PAGE analysis of reduced (red) and non-reduced (ox) samples of the IgE binding protein purified from dog urine by size exclusion and reversed phase chromatography. Lane M contains molecular weight marker proteins.
[0036] FIG. 4 shows the effect of kallikrein as a fluid-phase inhibitor on specific IgE binding to immobilized dog dander extract.
[0037] FIG. 5 a - b is an assessment by immunoblot analysis of IgE antibody reactivity to dog dander extract in 37 dog allergic subjects' sera. Prior to incubation with the membrane strips, serum samples were diluted as indicated. Lane M contains molecular weight marker proteins.
[0038] FIG. 6 shows a comparison of the immunoblot signal intensity of a 28 kDa band, corrected for serum dilution, and the level of kallikrein-specific IgE, as determined by experimental ImmunoCAP analysis. The ImmunoCAP and immunoblot detection limits applied are indicated by hatched lines. Immunoblot signal intensity is expressed in arbitrary units (AU).
[0039] FIG. 7 shows specific immunoblot inhibition of the 28 kDa protein band by purified dog urinary kallikrein. Lane M contains molecular weight marker proteins.
[0040] FIG. 8 shows the first step of purification of kallikrein from dog dander, by size exclusion chromatography. Six fractions (labeled 1-6) indicated in the figure were analysed for IgE binding activity.
[0041] FIG. 9 shows the second step of purification of kallikrein from dog dander, by reversed phase chromatography. Top fractions of three peaks indicated in the figure (labeled 1-3) were analysed for IgE antibody binding activity.
[0042] FIG. 10 shows a comparative immunoblot analysis specific IgE antibody binding to dog dander extract, purified urinary kallikrein and partially purified kallikrein from dog dander. Two kallikrein-reactive sera (no. 6 and 8) and one kallikrein non-reactive serum (no. 11) were used. Both reduced and non-reduced forms of the allergen preparations were analysed, as indicated in the legend. Lane M contains molecular weight marker proteins.
[0043] FIG. 11 shows SDS Page analysis of purified recombinant dog urinary kallikrein.
[0044] FIG. 12 shows analytical gelfiltration analysis of purified recombinant dog urinary kallikrein.
[0045] FIG. 13 shows a comparison of specific IgE antibody binding activity of natural and recombinant dog urinary kallikrein.
DETAILED DESCRIPTION OF THE INVENTION
[0046] The examples below illustrate the present invention with the isolation and use of kallikrein from dog. The examples are only illustrative and should not be considered as limiting the invention, which is defined by the scope of the appended claims.
Example 1
Detection and Isolation of an IgE Binding Protein from Dog Urine
[0047] In order to investigate whether dog urine may contain allergens relevant to dog allergy in humans, the following experiments were performed. Urine was collected from a 7 year old male crossbreed between Siberian Husky and Vorsteh. After filtration through a 0.45 μm mixed cellulose ester filter, 10 mL of urine was applied to a Superdex 75 size exclusion chromatography (SEC) column (XK26/100, V t =505 mL, GE Healthcare Biosciences, Uppsala, Sweden) equilibrated with 20 mM MOPS pH 7.6, 0.5 M NaCl (MBS) and elution was performed with the same buffer at a flow rate of 2 mL/min. Fractions from three peaks were pooled as indicated in the chromatogram shown in FIG. 1 and analysed for allergen activity. The protein content of each fraction was immobilized on ImmunoCAP (Phadia, Uppsala, Sweden) solid phase and its IgE antibody binding activity tested using eight sera from dog dander sensitized individuals. Most of these sera were selected as having high IgE binding to dog dander extract but relatively low binding to rCan f 1, rCan f 2 and nCan f 3. Of the three peaks tested, peak 2 was found to contain by far the highest level of IgE binding activity (Table 1). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) using the NuPAGE MES buffer system (10% NuPAGE gel, Invitrogen, Carlsbad, Calif., USA) of a reduced sample of peak 2 revealed two dominant protein bands, with apparent molecular weights of approximately 10 and 18 kDa, respectively (not shown).
[0048] Further protein purification from the pool corresponding to peak 2 was performed using a Source 15 reversed phase chromatography (RPC) column (ST4.6/100, V t =1.66 mL, GE Healthcare Biosciences). After addition of trifluoro acetic acid (TFA) to a final concentration of 0.065%, the pool was applied to the column, followed by washing with 9 column volumes of 0.065% TFA in water. Elution was performed with a 0-45% linear gradient of acetonitrile in water containing 0.05% TFA, resulting in one distinctive but somewhat asymmetrical peak ( FIG. 2 , peak indicated by an arrow). SDS-PAGE of reduced samples of fractions containing this peak revealed the presence of both the 10 and 18 kDa bands, seemingly unseparable ( FIG. 3 ). The fractions covering the entire peak were therefore pooled as indicated by horizontal bars in FIG. 2 . SDS-PAGE of a non-reduced sample of this pool revealed an additional band of 28 kD and a slight shift in mobility of the 10 kDa and 18 kDa bands ( FIG. 3 ). A faint protein band of approximately 55 kDa can also be seen in the non-reduced state, which may be a dimer of the 28 kDa protein. The occurrence of the 28 kDa band in the non-reduced state suggested that this protein may be made up of the 10 and 18 kDa polypeptides, joined together by one or more cystein bridge(s). The fact that linear mass spectromemetric analysis (data not shown) later showed dissociation of the 28 kDa component upon reduction and alkylation added further evidence to this notion.
Example 2
Identification of the IgE Binding Protein from Dog Urine as Prostate Kallikrein
[0049] Mass spectrometry and N-terminal sequencing was used to determine the identity of the IgE binding protein isolated from dog urine.
Peptide Mass Fingerprint Analysis by MALDI-TOF
[0050] For in-solution digestion of the RPC purified urinary protein, reduction and alkylation was performed by sequentialy adding to the sample DTT and iodoacetamide at approximately 45- and 100-fold molar excess, respectively. Trypsin digestion was then performed overnight at 37° C., using porcine trypsin (Trypsin Gold, mass spectrometry grade, Promega, Madison, Wis., USA). Samples containing digested peptides were spotted onto the MALDI target plate and α-cyano matrix in 50% acetonitrile, 10 mM NH 4 [H 2 PO 4 ], 0.1% TFA, was added. Following evaporation of the solvent, peptide mass fingerprinting (PMF) was performed in a Bruker Daltonics Autoflex 2 instrument (Bruker Daltonics, Bremen, Germany). To identify proteins matching PMF results obtained, the MSDB database was searched using a Mascot server (Matrixscience, London, UK). Post source decay (PSD) analysis was performed on selected peptides. External calibration was performed using a peptide calibration standard (Bruker Daltonics).
[0051] In-gel digestion analysis of the individual protein bands from SDS-PAGE was performed essentially according to Shevchenko (24). In summary, the 10, 18 and 28 kDa bands described in Example 1 above were excised from a Coomassie brilliant blue stained SDS-PAGE gel. The gel pieces were sequentially washed with 50 mM ammonium bicarbonate containing 50% acetonitrile followed by shrinking in pure acetonitrile. After rehydration of the gel piece with 50 mM ammonium bicarbonate, acetonitrile was added to 50% and following a second acetonitrile wash step, the gel pieces were dried in a vacuum centrifuge. eduction and alkylation was performed in sequence using 45 mM DTT and 100 mM iodoacetamide in 50 mM ammonium bicarbonate. After repeated washes with 50% acetonitrile in 50 mM ammonium bicarbonate and a final 100% acetonitrile wash, the gel particles were again dried down in a vacuum centrifuge. Trypsin digestion was performed overnight at 37° C. using porcine trypsin as described above. The digested sample was then sonicated and peptides extracted from the gel particles in 50% acetonitrile containing 0.1% TFA. Sample preparation and peptide mass fingerprinting was performed as described above.
[0052] The PMF analysis of the in-solution digested urinary protein resulted in a highly significant match (p<0.05) to prostatic kallikrein from dog (Accession no P09582). PSD analysis of two peptides, m/z=1224.6 and m/z=1632.8, which were also present in the in-gel digestion analysis of the 18 kDa band, gave significant database matches to the amino acid sequences FMLCAGVLEGK and SHDLMLLHLEEPAK, corresponding to residues 194-204 and 117-130, respectively, of the same protein database entry.
[0053] Corroborating results were obtained from analysis of the in-gel digested protein bands as PMF of the 28 kDa band also yielded a highly significant database match (p<0.05) to kallikrein from dog (P09582). Further evidence to the identity of the isolated urinary protein came from the analysis of in-gel digested samples of the 10 kDa band, PSD analysis of peptide m/z=1004.6 gave a highly significant (p<0.05) database match with the amino acid sequence SFIHPLYK, corresponding to residues 95-102 of P09582.
N-Terminal Amino Acid Sequencing
[0054] For N-terminal sequencing, the reduced 10 kDa and 18 kDa protein bands were excised separately from a SDS-PAGE gel and extracted in 6 M guanidinium-HCl, 20 mM Tris pH 8.0, 0.5 M NaCl, using a plastic rod for homogenization. N-terminal sequence analysis of the extracted 10 kDa and 18 kDa bands, performed using a Hewlett-Packard G1000A instrument (Hewlett-Packard, Palo Alto, Calif.), yielded the amino acid sequences IIGGREXLKN and AVIRPGEDRS, respectively, which were found to match residues 25-34 and 108-117 in the dog prostatic kallikrein precursor sequence of Accession no P09582.
[0055] Taken together, the results described in this example demonstrate that the major constituent of the purified dog urinary protein, corresponding to the 10 and 18 kDa bands in reducing SDS-PAGE analysis, is identical to prostatic kallikrein from dog. Further, the observations suggest that the 10 and 18 kDa polypeptides are formed by posttranslational cleavage of a primary gene product and are held together by disulfide bridges to form the 28 kDa protein seen under non-reducing conditions, similar to what has previously been described for human kallikrein (25).
[0056] Prostatic kallikrein is also known as arginine esterase and carries that designation in database entries describing identical or nearly identical amino acid sequences, including NP — 001003284, CAA68720 and AAA30831. Further, we note that another variant of kallikrein, expressed in renal, pancreatic and salivary gland tissues, has been identified in dog (Accession No CAA53210) and shares 68% amino acid identity with prostatic kallikrein.
Example 3
Assessment of IgE Binding Activity of Kallikrein, rCan f 1, rCan f 2 and nCan f 3
[0057] In vitro IgE binding activity of the purified recombinant and natural dog allergens were examined using ImmunoCAP® (Phadia, Uppsala, Sweden), an immunoassay system used for specific IgE antibody measurement in clinical diagnosis of atopic allergy. Recombinant Can f 1 and Can f 2 (5) were cloned and expressed in E. coli essentially as described (26). Dog albumin was purified from serum using anion exchange chromatography and Blue Sepharose affinity chromatography, essentially as described (27). Experimental ImmunoCAP tests were prepared and used for serum analysis as described (26).
[0058] Sera from 37 dog allergic patients from Sweden (n=9), Spain (n=23) and North America (n=4) were used in the study. All patients had a positive skin prick test for dog dander extract and a doctors' diagnosis of dog allergy with symptoms of asthma, rhinoconjunctivitis and/or urticaria. All of the sera had a positive specific IgE test (ImmunoCAP) to dog dander extract.
[0059] The levels of specific IgE to dog dander extract, rCan f 1, rCan f 2, nCan f 3 and purified kallikrein are shown in Table 2 and a summary of the results is shown in Table 3. Of the tested sera, 29 showed IgE reactivity to kallikrein and 18 to rCan f 1. Both rCan f 2 and nCan f 3 appeared as minor allergens among the subjects studied, binding IgE from only 8 and 6 of 37, respectively. Fourteen of the 37 sera (38%) reacted only to kallikrein. On average among the kallikrein-reactive sera, the level of IgE binding to kallikrein amounted to 64% of the IgE binding to dog dander. The corresponding relative levels of IgE binding to rCan f 1, rCan f 2 and nCan f 3 were 45%, 25% and 47%, respectively, among sera specifically reactive to those allergens. Only two of the 37 sera tested lacked IgE reactivity to all of the four dog allergens. The IgE binding to kallikrein showed no correlation to any of the other dog allergens, demonstrating that the immune response to kallikrein is an independent variable and not a result of cross reactivity to Can f 1, Can f 2 or Can f 3.
[0060] The results obtained clearly demonstrated that prostatic kallikrein from dog is a major and unique allergen among the dog allergic subjects studied here. By both prevalence and magnitude of IgE binding, kallikrein was found to be the most important dog allergen so far described and among the subjects studied, over one third reacted to kallikrein but none of the other allergens tested.
Example 4
Demonstration of Kallikrein-Specific IgE Antibody Binding Activity in Dog Dander Extract
[0061] An IgE inhibition experiment was performed to examine whether dog dander contains epitopes capable of binding kallikrein-reactive IgE antibodies. Serum samples from three dog sensitized subjects (A-C) with IgE reactivity to kallikrein were first incubated for 2 h at room temperature with purified kallikrein at a final concentration of 100 μg/mL and, in parallel as negative controls, with serum diluent or the non-allergenic maltose binding protein (MBP) of E. coli . All samples were then analysed in duplicate for IgE binding to ImmunoCAP tests carrying immobilized dog dander extract to study whether preincubation with kallikrein specifically would prevent IgE binding to dander protein attached to the solid phase. As a control for specificity of kallikrein as inhibitor, a serum from a subject (D) sensitized to Can f 1 and Can f 2, but not to kallikrein, was included alongside the other sera in the experiment.
[0062] The results of the inhibition experiment are shown in FIG. 4 . Kallikrein purified from dog urine was found to completely inhibit the IgE binding to dog dander of two (A and B) of the three kallikrein-reactive sera and partly the binding of the third serum (C), which was known to be reactive also to other dog allergens. The negative control protein, MBP, showed no significant inhibitory effect as compared to serum diluent. In addition, no inhibition by kallikrein was observed on IgE binding of the Can f 1- and Can f 2-reactive serum (D).
[0063] The results demonstrated that epitope structures capable of binding kallikrein-reactive IgE antibodies are present in dog dander and, hence, are not confined to urine.
Example 5
Assessment of IgE Binding to a Kallikrein-Like 28 kDa Protein from Dog Dander Extract Using Immunoblot Analysis
[0064] With the aim to identify a protein present in dog dander to which the observed kallikrein-like allergen activity may be attributed, 37 sera with known levels of kallikrein-reactive IgE were used in an immunoblot experiment. Immunoblot analysis was performed on non-reduced dog dander extract separated by SDS-PAGE (12.5% Excel 2-D gel, GE Healthcare Biosciences) and electroblotted onto nitrocellulose membrane (Hybond ECL, GE Healthcare Biosciences). Protein blots were blocked for 1 h at room temperature using blocking buffer (50 mM phosphate pH 7.4, 0.1% (v/v) Tween-20, 0.9% (w/v) NaCl, 0.3% w/v) Dextran T10) and then incubated overnight with each patient's serum, diluted 1.5- to 20-fold in blocking buffer. The dilution factor for each serum is indicated in brackets at the top of its corresponding membrane strip in FIG. 5 . After washing in blocking buffer with 0.5% (v/v) Tween-20, the membrane was incubated 4 hrs at room temperature with an 125 I-labelled anti-human IgE antibody in blocking buffer and bound IgE was then radiographically detected using a storage phosphor screen and a Variable Mode Imager, Typhoon 9410 (GE Healthcare Biosciences).
[0065] The results of the experiment are shown in FIG. 5 a - b . Of the 37 sera used, 30 showed IgE binding to a 28 kDa protein while 21 showed IgE binding to a 23 kDa band, corresponding to Can f 1 and/or possibly Can f 2. Immunoblotting signal intensities were quantified using the Phoretix 1D software (Nonlinear Dynamics Ltd, Newcastle upon Tyne, UK). The level of IgE reactivity in each serum to individual bands was calculated by multiplying the signal intensity with the serum dilution factor. FIG. 6 shows a comparison of the level of IgE binding to the 28 kDa band in immunoblot analysis and the kallikrein ImmunoCAP measurements described in Example 3 above, revealing a close correlation.
[0066] In order to directly examine the relationship between urinary kallikrein and the 28 kDa band in dog dander, an immunoblot inhibition experiment was performed. A serum mono-reactive to the 28 kDa band was preincubated 2 hrs at room temperature with either purified urinary kallikrein or rCan f 1, both at a final concentration of 100 μg/mL, or with serum diluent. Membrane strips carrying immunoblottted non-reduced dog dander extract were then subjected to the preincubated serum samples and IgE binding was analysed as described above. The experiment revealed that IgE binding to the 28 kDa band in dog dander was completely abolished by serum preincubation with kallikrein whereas it remained unaffected by preincubation with both rCan f 1 and buffer alone ( FIG. 7 ).
[0067] Taken together, the results described in this example demonstrated the presence in dog dander extract of a protein displaying close electrophoretic and immunological similarity to urinary kallikrein.
Example 6
Partial Purification and Identification of Kallikrein in Dog Dander
[0068] The kallikrein-like protein from dog dander was purified by SECand RPC for biochemical identification. Three grams of dog dander (Allergon, Välinge, Sweden) was extracted in a 100 mL of MBS by end-over-end rotation for 3 hrs at room temperature. After centrifugation at 20,000×g and concentration using an Amicon filter (PM-10, Millipore, Billerica, Mass., USA), the extract was applied to an XK50/100 Superdex 75 column (GE Healthcare Biosciences) and eluted using MBS ( FIG. 8 ). Fractions from six peaks (indicated 1-6 in FIG. 8 ) were pooled and analysed for allergen activity. The protein content of each fraction was immobilized on ImmunoCAP (Phadia, Uppsala, Sweden) solid phase and its IgE antibody binding activity tested using eight sera from dog dander sensitized individuals, as indicated in Table 4. Most of these sera were selected as having high IgE binding to dog dander extract but relatively low binding to either of rCan f 1, rCan f 2 and nCan f 3. From Table 4 it is evident that peak 3 from the SEC separation contained the highest level of IgE binding activity of the six peaks tested. This pool was selected for further purification.
[0069] After adding TFA to a final concentration of 0.065%, the pool was applied to a ST4.6/100 Source 15 RPC column (GE Healthcare Biosciences) and elution was performed using a linear, 0-54% gradient of acetonitril in water containing 0.05% TFA ( FIG. 8 ). Analysis of allergen reactivity of the three peaks indicated in FIG. 9 was performed using five sera, selected by the criteria described above, The results of the analysis (Table 5) clearly showed that peak 1 contained the highest level of IgE antibody binding. Reducing SDS-PAGE analysis of this peak revealed the presence of 10 kDa, 18 kDa and 23 kDa protein bands (not shown).
[0070] The three band present in peak 1 were excised from the gel and subjected to in-gel digestion and mass spectrometric analysis as described in Example 2 above. While the 23 kDa band was identified as Can f 1, both the 10 kDa and 18 kDa bands were identified as dog prostatic kallikrein (Accession no P09582) after PSD analysis of selected peptides m/z=1004.52 and m/z=1632.98, respectively.
[0071] Further, the two 10 kDa and 18 kDa bands were eluted from excised gel bands and subjected to N-terminal amino acid sequencing. The resulting sequences, xIGGRExLKN and AVxRPGEDRx, where “x” represents unresolved residues, matched residues 25-34 and 108-117 of the canine prostatic kallikrein precursor sequence, Accession no P09582.
[0072] The results described in this example demonstrated that a protein with a primary structure identical or closely related to prostatic kallikrein is present in dog dander.
Example 7
Similar IgE Antibody Reactivity to Kallikrein from Dog Dander and Urine
[0073] To compare the IgE antibody binding activity of kallikrein from dog urine and dander, two kallikrein-reactive sera (sera no 6 and 8 from Table 2) and one kallikrein non-reactive serum (no 11) were used in immunoblot analysis of non-reduced samples of dog dander extract, purified urinary kallikrein and partially purified kallikrein from dog dander ( FIG. 10 ). The two kallikrein-reactive sera displayed IgE binding to a 28 kDa band in all three preparations, indicating that IgE binding at 28 kDa in dog dander extract is due to kallikrein. In addition, it was evident that the dominant reactivity to the 28 kDa band in purified urinary kallikrein coincided with the Coomassie stained protein bands of the same preparation. IgE binding to a band of about 55 kDa in the non-reduced kallikrein preparations is consistent with the notion in Example 1 above, of a putative dimer of kallikrein. The serum that was kallikrein non-reactive according to ImmunoCAP showed no IgE binding to the 28 kDa band in any of the three allergen preparations analysed.
[0074] The immunoblotting reactivity to reduced kallikrein-containing samples was considerably weaker than to non-reduced samples. Only the purified urinary kallikrein preparation, which had a higher kallikrein concentration than the other preparations analysed, gave rise to detectable IgE binding to the 18 kDa band formed upon reduction.
[0075] The observation that the immune reactivity to purified urinary kallikrein in immunoblot analysis was directed against the major protein band at 28 kDa served to support the validity of the experimental kallikrein ImmunoCAP test, in that its IgE binding was not caused a contaminant of the protein preparation used. The results further show that at least some IgE binding epitopes on kallikrein are sensitive to reduction of the molecule, as indicated by the weaker antibody binding to the 10 kDa and 18 kDa subunits, as compared to the 28 kDa unreduced molecule.
Example 8
Assessment of IgE-Binding Properties of a Modified Kallikrein or a Variant or Fragment of Kallikrein (Analyte)
[0076] The analyte is immobilized to a solid support, such as ImmunoCAP (Phadia, Uppsala, Sweden). Serum samples from at least three representative human patients sensitized to the relevant species and showing IgE reactivity to kallikrein from that species are incubated for 3 h at room temperature with kallikrein at a final concentration of 100 μg/mL and, in parallel as negative controls, with buffer alone and the non-allergenic maltose binding protein (MBP) of E. coli . The samples are then analysed for IgE binding to ImmunoCAP (Phadia, Uppsala, Sweden) tests carrying immobilized analyte to study whether preincubation with kallikrein specifically inhibits or significantly lowers IgE binding.
Example 9
Purification of Kallikrein from Dog Urine by Hydrophobic Interaction Chromatography (HIC)
[0077] A pooled sample of dog urine was filtered through a 5 μm and a 0.45 μm filter under nitrogen pressure. All chromatographic operations were performed with an ÄKTA Explorer 100 Air system (GE Healthcare Biosciences, Uppsala, Sweden). Four aliquots of 120 ml filtered dog urine was buffer exchanged using a Sephadex G-25 column (GE Healthcare Biosciences, Uppsala, Sweden) (column volume 461 ml), with cleaning of the column after each run. Buffer used: 50 mM Na-phosphate, 1 M (NH 4 ) 2 SO 4 , 0.02% NaN 3 , pH=7. The sample (about 505 ml) was then filtered through a 0.45 μm filter and applied to the HIC column (HiPrep Phenyl FF (high sub), 20 ml, GE Healthcare Biosciences, Uppsala, Sweden). Buffers used for HIC separation were: A) 50 mM Na-phosphate, 1 M (NH 4 ) 2 SO 4 , 0.02% NaN 3 , pH=7, and B) 50 mM Na-phosphate, 0.02% NaN 3 , pH=7. The flow through fraction (containing kallikrein) was collected in 10 ml fractions (Frac 950) at a flow rate of 5 ml/min and the flow through fractions were then pooled. The adsorbed material was eluted in a step gradient using 100% buffer B.
[0078] The fractions were analyzed using a BCA (bicinchoninic acid) assay, as well as SDS-PAGE (non reduced samples, silver staining). SDS-PAGE under non-reducing conditions revealed that kallikrein was found in the flow-through fractions which thus were pooled for further processing.
[0079] Two aliquots of about 125 ml and one aliquot of about 87 ml of the pooled HIC flow through fractions were buffer exchanged with a Sephadex G-25 SF column (GE Healthcare Biosciences, Uppsala, Sweden) to a buffer with the composition 20 mM Na-phosphate, 0.02% NaN 3 , pH=8. The kallikrein-pool (456 ml) was then concentrated on an Amicon cell (350 ml, Millipore filter, PBCC, cutoff 5000 kDa, diameter 76 mm) to a volume of about 43 ml. Using BCA assay, the protein concentration in the final pool was determined to be 0.9 mg/ml (in 43 ml=totally 38.7 mg) The sample applied to the HIC-column contained 101 mg protein which yielded a recovery of 38% of kallikrein after the HIC purification.
[0080] The purity of the kallikrein preparation was assessed by analytical gel filtration on a Superdex 75 HR 10/30 column in an ÄKTA purifier XT10 system. For this experiment the sample volume was 100 μl and the buffer was 10 mM Na-phosphate, 150 mM NaCl, 0.02% NaN 3 , pH=7.4.
Example 10
Identification and Characterization of Kallikrein from Dog Urine by the Use of Electrophoresis and Mass Spectrometry
[0081] Using electrophoresis the following samples were compared on the same gel, applying colloidal coomassie brilliant blue (CBB) staining:
[0082] 1. A standard molecular weight marker
[0083] 2. Dog urine
[0084] 3. HIC-eluted material (reduced)
[0085] 4. HIC flow-through fraction (reduced)
[0086] 5. HIC flow-through fraction (non-reduced)
[0087] 6. HIC-eluted material (non-reduced)
[0088] For samples 2, 3 and 6, a large number of proteins were detected. However, in sample 4 (reduced HIC flow-through fraction), only two main bands could be seen. These two bands were later, by the use of MALDI-TOF(-TOF) analysis (see below), found to correspond to two different variants of the kallikrein protein (as a result of proteolysis at R107, due to arginin-esterase activity). In sample 5 (non-reduced HIC flow-through fraction), seven distinct bands were detected and all bands were found to correspond to different variants of the kallikrein protein by the use of MALDI-TOF(-TOF) analysis (see below). Kallikrein comprises 12 cystein-residues, therefore the formation of different variants is possible under non-reducing conditions due to formation of cystein-cystein bridges. Thus, the formation of for example dimers, trimers etc is likely to happen under non-reducing conditions.
SDS-PAGE Conditions, Trypsin Digestion and MALDI-TOF-TOF Analysis:
[0089] Diluted samples were prepared using a SDS-PAGE cleanup kit according to the procedure recommended in the manual from the supplier (GE Healthcare, Uppsala, Sweden). The gels were run in a MES buffer at 200 V for 35 minutes. Reduced and non-reduced samples were run in separate aggregates. Staining was done overnight with colloidal CBB (de-staining was later done using water immersion for about 5 hours). Samples were manually picked from the gel using a pipette tip, and treated according to a standard protocol (using ethanol instead of acetonitrile), incubated with 12.5 ng/μl trypsin over night at 37 degrees Celsius. 0.5 μl of the digested samples was applied on the target plate for the MALDI system and mixed with 0.5 μl MALDI matrix solution (saturated solution of HCCA in 50% acetonitril, 0.1% TFA). All samples were analyzed, using a MALDI-TOF-TOF (Bruker Daltonics, Bremen, Germany) mass spectrometer. To identify proteins matching PMF results obtained, the MSDB database was searched using a Mascot server (Matrixscience, London, UK). MS-MS analysis was performed on selected peptides. External calibration was performed using a peptide calibration standard (Bruker Daltonics). Database searches were run using the following search criteria:
[0090] Taxonomy: mammalia
[0091] Mass tolerance: 100 ppm
[0092] Allowing for oxidized methionines and 1 missed cleavage.
[0093] Kallikrein sequence from the database:
[0000]
(SEQ ID NO: 1)
MWFLALCLAMSLGWTGAEPHFQPRIIGGRECLKNSQPWQVAVYHNGEFAC
GGVLVNPEWVLTAAH HNLSESEDEGQLVQVRK
--------- TKAVR
VMDLPKKEPPLGSTCYVSGWGSTDPETIFHPGSLQCVDLKLLSNNQCAKV
YTQKVTK KDTCKGDSGGPLICDGELVGITSWGATPCGKP
QMPSLYTR ANT
(Peptide sequences identified by MALDI-TOF (/TOF)
MS (/MS) in bold italic.)
Example 11
Cloning, Purification and Assessment of the IgE Binding Activity of Recombinant Dog Kallikrein Expressed in Pichia pastoris
[0094] In order to verify the identification and importance of urinary kallikrein as a dog allergen, the protein was produced as a recombinant allergen using Pichia pastoris as expression host, purified and analysed for IgE antibody binding activity.
Preparation of Synthetic Gene Construct Encoding Dog Urinary Kallikrein
[0095] A synthetic dog urinary kallikrein gene was designed by back-translating into nucleotide sequence the part of the reported amino acid sequence of dog prostatic arginine esterase (urinary kallikrein, Acc. No. P09582) corresponding to the mature protein. The nucleotide sequence was designed for optimal codon usage and synonymously adjusted to minimize secondary structures and eliminate or add restriction enzyme sites as desired. Oligonucleotides corresponding to the final coding sequence were obtained and assembled, and the full-length synthetic gene amplified by PCR and cloned into the XhoI and SalI sites of vector pPICZ A (Invitrogen, Carlsbad, Calif., USA), adding a C-terminal hexahistidine tag to enable protein purification by immobilised metal ion affinity chromatography (IMAC). The plasmid DNA construct was linearized by Sac I digestion and transformed into P. pastoris strain X-33 for homologous recombination into the chromosomal AOX1 locus.
Expression and Purification of Recombinant Dog Kallikrein-2
[0096] The recombinant protein was produced in Pichia pastoris strain X-33 (Invitrogen) using a 7 L bioreactor (Belach Bioteknik, Solna, Sweden). A rich broth medium (20 g/L peptone, 10 g/L yeast extract, 3.4 g/L yeast nitrogen base, 10 g/L ammonium sulfate, 0.4 mg/L biotin and 0.1 M potassium phosphate) was used and the cultivation carried out at 30° C. Expression was induced and maintained by feeding methanol to the culture to a steady-state concentration of 0.1% (v/v). After 70 hrs of fermentation, the culture was harvested by centrifugation at 10 000 g for 10 min at +4° C. and the supernatant recovered for protein purification.
[0097] The supernatant was conditioned for purification by adding imidazole to 5 mM and NaCl to 0.15 M and adjusting the pH to 7.2 using Tris base (s) before applying it to a Streamline 25 chelating column (GE Healthcare Biosciences), charged with NiSO 4 according to the manufacturer's recommendation. After loading, the column was washed in separate steps with 20 mM and 60 mM imidazole and the recombinant protein was then eluted with 500 mM imidazole, all in a buffer composed of 20 mM Tris-HCl pH 8.0 and 0.15 M NaCl.
[0098] Further purification of the recombinant protein was performed using cation exchange chromatography. IMAC fractions containing recombinant kallikrein were identified by SDS-PAGE, pooled and diluted with 2 volumes of 20 mM MES pH 6.0. After adjusting pH to 6.0, the diluted pool was applied to an XK26/100 SP Sepharose FF column (GE Healthcare Biosciences). The column was then washed with 2 column volumes of 0.15 M NaCl in 20 mM MES pH 6.0 and the recombinant protein eluted with 0.30 M NaCl in the same buffer. The protein concentration was determined from absorbance at 280 nm, using a calculated extinction coefficient of 1.46 per mg/mL.
[0099] Although the synthetic kallikrein gene construct was designed to direct the production of a single polypeptide chain, the protein purified from the culture medium was found to have undergone a partial cleavage into 18 kDa and 12 kDa chains ( FIG. 11 ), similar to the processing of natural urinary kallikrein. Indeed, N-terminal sequencing revealed that the recombinant kallikrein had been cleaved at the same position as the natural molecule (data not shown).
[0100] To assess the aggregation state and integrity of the recombinant protein under physiological conditions, a sample of the preparation was subjected to analytical size exclusion chromatography. As shown in FIG. 12 , the chromatogram was dominated by a single symmetrical peak, corresponding to a molecular weight of 34 kDa as defined by the LMW Calibration Kit (GE Healthcare Biosciences). The analysis demonstrated that the recombinant protein, despite its partial processing, was held together in solution and existed in a homogeneous, most likely monomeric, aggregation state.
IgE Binding Activity of Recombinant Kallikrein
[0101] The immunological activity of the recombinant kallikrein produced was assessed in comparison to the natural protein purified from dog urine. The two proteins were immobilised separately on ImmunoCAP® solid phase and their in vitro IgE binding capacity was examined using the 37 serum samples from dog allergic subjects described in Example 3 above.
[0102] As can be seen in FIG. 13 , the two datasets showed a very strong correlation (r=0.9988), demonstrating that the recombinant kallikrein produced closely resembled natural urinary kallikrein with respect to IgE antibody binding. Drawing from the complete absence of any other dog-derived protein in the recombinant protein preparation, it can be further noted that the results eliminate any possible doubt as to the identity of the active component of the natural kallikrein preparations described in the previous examples.
REFERENCES
[0000]
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2. Spitzauer S, Schweiger C, Anrather J, Ebner C, Scheiner O, Kraft D et al. Characterisation of dog allergens by means of immunoblotting. International Archives of Allergy and Immunology 1993; 100:60-67.
3. Spitzauer S. Allergy to mammalian proteins: At the borderline between foreign and self? [Review]. International Archives of Allergy and Immunology 1999; 120:259-269.
4. de Groot H, Goei K G H, van Swieten P, Aalberse R C. Affinity purification of a major and a minor allergen from dog extract: serologic activity of affinity-purified Can f I and of Can f I-depleted extract. Journal of Allergy and Clinical Immunology 1991; 87:1056-1065.
5. Konieczny A, Morgenstern J P, Bizinkauskas C B, Lilley C H, Brauer A W, Bond J F et al. The major dog allergens, Can f 1 and Can f 2, are salivary lipocalin proteins: cloning and immunological characterization of the recombinant forms. Immunology 1997; 92:577-586.
6. Boutin Y, Hebert H, Vrancken E R, Mourad W. Allergenicity and cross-reactivity of cat and dog allergenic extracts. Clinical Allergy 1988; 18:287-293.
7. Saarelainen S, Taivainen A, Rytkonen-Nissinen M, Auriola S, Immonen A, Mantyjarvi R et al. Assessment of recombinant dog allergens Can f 1 and Can f 2 for the diagnosis of dog allergy. Clinical & Experimental Allergy 2004; 34:1576-1582.
8. Cabanas R, Lopez-Serrano M C, Carreira J, Ventas P, Polo F, Caballero M T et al. Importance of albumin in cross-reactivity among cat, dog and horse allergens. Journal of Investigational Allergology & Clinical Immunology 2000; 10:71-77.
9. Bayard C, Holmquist L, Vesterberg O. Purification and identification of allergenic alpha (2u)-globulin species of rat urine. Biochim Biophys Acta 1996; 1290:129-134.
10. Ohman J L. Allergy in man caused by exposure to mammals. J Am Vet Med Assoc 1978; 172:1403-1406.
11. Schumacher M J. Characterization of allergens from urine and pelts of laboratory mice. Mol Immunol 1980; 17:1087-1095.
12. Siraganian R P, Sandberg A L. Characterization of mouse allergens. Journal of Allergy and Clinical Immunology 1979; 63:435-442.
13. Taylor A N, Longbottom J L, Pepys J. Respiratory allergy to urine proteins of rats and mice. Lancet 1977; 2:847-849.
14. Hoffman D R. Dog and cat allergens: urinary proteins or dander proteins? Annals of Allergy 1980; 45:205-206.
15. Hiller R, Laffer S, Harwanegg C, Huber M, Schmidt W M, Twardosz A et al. Microarrayed allergen molecules: diagnostic gatekeepers for allergy treatment. FASEB Journal 2002; 16:414-416.
16. Valenta R, Lidholm J, Niederberger V, Hayek B, Kraft D, Gronlund H. The recombinant allergen-based concept of component-resolved diagnostics and immunotherapy (CRD and CRIT). Clinical & Experimental Allergy 1999; 29:896-904.
17. Cromwell O, Fiebig H, Suck R, Kahlert H, Nandy A, Kettner J et al. Strategies for recombinant allergen vaccines and fruitful results from first clinical studies. Immunol Allergy Clin North Am 2006; 26:261-281, vii.
18. Gafvelin G, Thunberg S, Kronqvist M, Gronlund H, Gronneberg R, Troye-Blomberg M et al. Cytokine and antibody responses in birch-pollen-allergic patients treated with genetically modified derivatives of the major birch pollen allergen Bet v 1. International Archives of Allergy and Immunology 2005; 138:59-66.
19. Jutel M, Jaeger L, Suck R, Meyer H, Fiebig H, Cromwell O. Allergen-specific immunotherapy with recombinant grass pollen allergens. Journal of Allergy and Clinical Immunology 2005; 116:608-613.
20. Mahler V, Vrtala S, Kuss O, Diepgen T L, Suck R, Cromwell O et al. Vaccines for birch pollen allergy based on genetically engineered hypoallergenic derivatives of the major birch pollen allergen, Bet v 1. Clinical & Experimental Allergy 2004; 34:115-122.
21. Weidinger S, Mayerhofer A, Raemsch R, Ring J, Kohn F M. Prostate-specific antigen as allergen in human seminal plasma allergy. Journal of Allergy and Clinical Immunology 2006; 117:213-215.
22. Demoly P, Lebel B, Arnoux B. Allergen-induced mediator release tests. Allergy 2003; 58:553-558.
23. Ebo D G, Hagendorens M M, Bridts C H, Schuerwegh A J, De Clerck L S, Stevens W J. In vitro allergy diagnosis: should we follow the flow?[Review]. Clinical & Experimental Allergy 2004; 34:332-339.
24. Shevchenko A, Wilm M, Vorm O, Mann M. Mass spectrometric sequencing of proteins silver-stained polyacrylamide gels. Anal Biochem 1996; 68:850-858.
25. Frenette G, Deperthes D, Tremblay R R, Lazure C, Dube J Y. Purification of enzymatically active kallikrein hK2 from human seminal plasma. Biochim Biophys Acta 1997; 1334:109-115.
26. Marknell DeWitt Å, Niederberger V, Lehtonen P, Spitzauer S, Sperr W R, Valent P et al. Molecular and immunological characterization of a novel timothy grass ( Phleum pratense ) pollen allergen, Phl p 11. Clinical 85 Experimental Allergy 2002; 32:1329-1340.
27. van Eijk H M, Rooyakkers D R, van Acker B A, Soeters P B, Deutz N E. Automated isolation of high-purity plasma albumin for isotope ratio measurements. J Chromatogr B Biomed Sci App 1999; 731:199-205.
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Prostatic kallikrein for the manufacture of a diagnostic or pharmaceutical composition for diagnosis/treatment of type 1 allergy, especially allergy to dogs.
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BACKGROUND OF THE INVENTION
The continuous casting of metal in a peripheral groove around a rotating casting wheel is well known in the metal foundry art. In the casting of metal in these rotating casting wheels, it has been found that the metal solidifies in three distinct phases as it cools. The first phase begins when the liquid metal is fed into the peripheral groove of the casting wheel and includes that portion of the casting process during which the metal is cooled but is completely liquid within the casting wheel so as to be in complete contact with the casting wheel. The second phase is that portion of the casting process during which the continued cooling of the metal causes an outer crust of solidified metal to form adjacent the casting wheel but during which the metal is still in substantially complete contact with the casting wheel. The third phase is that portion of the casting process beginning generally at or near the point in the solidification of the molten metal at which the continued cooling of the metal and the thickening of the outer crust of solidified metal causes the metal to shrink away from the casting wheel and form an air gap between the metal and the casting wheel. Thus, the third phase includes that portion of the casting process during which the air gap prevents complete contact between the hot metal bar and the casting wheel. The metal bar may not be completely solidified and therefore requires further cooling.
It is this third phase of solidification that is most troublesome in the casting of molten metal in prior art rotating casting wheels since the air gap formed between the cast metal and the casting wheel greatly reduces the rate of heat transfer from the metal to the casting wheel. This is because the heat must be transferred from the cast metal to the casting wheel, in the third phase, principally by radiation heat transfer through the air in the gap between the cast metal and the casting wheel rather than by conduction heat transfer as in the first and second solidification phases, and because less heat can be transferred by radiation heat transfer than by conduction heat transfer at the same relative temperatures.
The low rate of heat transferred during the third phase of solidification in a prior art casting wheel in turn results in limiting the maximum rotational speed of the casting wheel, hence limiting the casting rates that can be achieved. This is because the rotational speed of a prior casting wheel must be slow enough to provide a sufficient dwell time of the metal in the casting wheel during the third phase for the metal to solidify sufficiently in the casting wheel, and because the length of the arcuate casting mold available for the third phase of solidification is limited by structural considerations.
This serious limitation of the maximum casting rate has been recognized in some prior art attempts to increase the cooling of the cast bar during its last phase of solidification. However these attempts are generally not successful in actual practice due to the complex apparatus which often fails to work under the harsh conditions of industrial production. The methods and apparatus disclosed in U.S. Pat. Nos. 3,261,059 and 3,575,231 are exemplary of this prior art.
These patents essentially disclose the use of multiple rollers or wheels for guiding and holding the band away from the casting wheel so that a fluid can be forced entirely around the hot cast bar, totally filling the solidification gap, functioning either as a heat-transfer medium to conduct heat across the gap to the walls of the mold, or as a direct coolant medium to directly cool the peripheral surfaces of the cast bar.
However, not only do these methods fail to achieve the same degree of cooling that can be achieved by direct contact between the cast bar and the walls of the casting groove, but by removing the band from contact with the cast bar and permitting the bar to drop downwardly out of the casting groove so that the fluid can be caused to flow entirely therearound, the bar is no longer firmly supported by the walls of the mold. Consequently, under these conditions, the internal stresses in the still-soft cast bar tend to cause it to deform or even crack, thus adversely affecting the quality of the cast product. Moreover, the use of rollers to deflect the band away from the periphery of the casting wheel induces additional stresses in the band which adversely affects its useful life. Furthermore, in actual practice, these rollers often become inoperable due to an accumulation of metal spilled during the casting operation.
SUMMARY OF THE INVENTION
In view of the foregoing, it should be apparent that a need still exists in the art for an effective method and apparatus for overcoming the problems of solidification shrinkage in the third phase of solidification in continuous casting systems.
Accordingly, it is a primary object of this invention to provide a method and apparatus for substantially eliminating the shrinkage gap between the cast bar and the walls of the peripheral casting groove in the third phase of solidification.
More particularly, it is an object of this invention to provide a method and apparatus for urging the at least partially solidified cast bar into contact with the walls of the casting groove during the third phase of solidification so as to close the shrinkage gap therebetween.
Another object of this invention is to provide a method and apparatus for injecting a fluid into the casting mold between the casting band and the cast bar, and to permit a build-up of fluid pressure therein sufficient to force the bar into contact with the wall surfaces of the peripheral casting groove.
Yet another object of this invention is to provide a method and apparatus for removing the casting band from the periphery of the casting wheel, to permit a fluid to be injected into the interior of the mold, while substantially maintaining support of the cast bar by the walls of the mold.
A further object of this invention is to provide a method and apparatus for injecting fluid into the mold cavity of a continuous casting machine, while avoiding the problems associated with fouling of the rollers used in prior art apparatus to remove the casting band from the periphery of the casting wheel, and to eliminate the stresses induced in the band by the use of such rollers.
Still another object of this invention is to provide a method and apparatus for continuous casting of molten metal, and to improve the heat transfer from the metal in the mold and thus increase the casting rate of the system.
Briefly stated, these and other objects of the invention that may become apparent hereinafter, are accomplished in accordance with the invention by directing high pressure jets of fluid against at least one marginal edge of the casting band along the arcuate length of the mold corresponding to the third casting zone (i.e., wherein the third phase of solidification occurs), said jets serving to lift the band from the periphery of the casting wheel and permit entry of fluid into the mold. The apparatus of the invention includes an arcuate manifold disposed adjacent the periphery of the casting wheel, and having a plurality of nozzles extending therefrom which are adapted to emit high pressure fluid jets against at least one marginal edge of the inner surface of the casting band with a force sufficient to lift the band from the periphery of the wheel and thus permit ingress of the fluid into the interior of the mold. The fluid both functions to directly cool the band-side surface of the cast bar, and additionally vaporizes at the temperature of the casting operation thereby generating an increase in fluid vapor pressure which forces the cast bar firmly into contact with the walls of the casting groove for improved conduction heat transfer therefrom during some, or all, of the third solidification phase. The present apparatus also serves to accelerate solidifying of the metal internally of the casting wheel at a relatively high rate of heat transfer while at the same time supporting the metal during the cooling process in a manner that reduces or eliminates breaks or voids in the cast bar.
The method of the present invention allows the rotational speed of the casting wheel to be increased and also allows an efficient rate of heat transfer to be achieved during some or all of the third solidification phase, an object not easily achieved by prior art cooling methods.
With the above and other objects of the invention that become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the attached drawings, the following detailed description thereof, and the appended claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of one embodiment of the invention adapted to a typical continuous casting machine;
FIG. 2 is an enlarged cross sectional view taken near the bottom of the casting wheel of FIG. 1 showing the usual shrinkage gap characteristic of prior art systems;
FIG. 3 is an enlarged cross sectional view taken near the bottom of casting wheel of FIG. 1 showing the present invention; eliminating the shrinkage gap and cooling the cast bar directly;
FIG. 4 is a schematic representation of the three phases of solidification in the typical casting machine of FIG. 1;
FIG. 5 is a graph comparing the relative cooling rates during solidification when practicing the present invention as compared to the cooling rate in the prior art casting methods;
FIG. 6 is an enlarged side elevation view of the casting wheel of FIG. 1, and depicts the casting band having been lifted from the periphery of the casting wheel under the force of the fluid jets, along a given segment of the arcuate mold, but wherein the band is in sealing contact with the peripheral surface of the casting wheel along substantial segments extending inwardly from the inlet and outlet, respectively, of the arcuate mold.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in more detail to the drawings, in which like numerals of reference illustrate like parts throughout the several views, FIG. 1 depicts a casting wheel 10 having an endless flexible band 11 positioned against a portion of its periphery by four support wheels 14, 19, 18, and 17. The band support wheel 14 is positioned near a point 16 on the casting wheel 10 where molten metal is fed from a pouring pot 26 into the casting mold M formed by the peripheral groove in wheel 10 and the band 11. Support wheel 17 is positioned at the opposite end of the mold where cast metal C is discharged after being sufficiently solidified. One or more other support wheels, such as 18 and 19, guide the endless band back to its starting point while maintaining a sufficient tension in the band so that it sealingly engages the casting wheel throughout the portion containing the cast metal.
Not shown in FIG. 1 are conventional cooling manifolds associated with the casting apparatus which include spray assemblies positioned to cool the interior of the wheel 10 and the exterior of the band 11. These conventional cooling manifolds are well known in the art and disclosed in detail in U.S. Pat. No. 3,279,000.
As seen in FIG. 4, the molten metal undergoes three phases of solidification in the casting wheel 10. As explained above, the metal in phase one is completely molten and fills the casting mold completely and is in contact with the wall surfaces thereof. In phase two the metal forms an outer solid skin, but still includes a molten metal core. In phase three the metal continues to solidify as it is cooled and beings to shrink away from the walls of the casting mold. This phenomenon is illustrated most clearly in FIG. 2 wherein there is illustrated a gap G existing between the at least partially solidified cast bar and the walls of the arcuate mold, including both the walls of the peripheral groove in the casting wheel 10 and the inner surface of the band 11.
In accordance with the present invention, the casting apparatus illustrated in FIG. 1 is provided with one or more cooling manifolds 13 having a plurality of spray nozzles 12 extending therefrom. The nozzles 12 are adapted to emit high pressure jets of fluid against a marginal edge of the inner surface of the casting band 11 as seen most clearly in FIG. 3 with a force sufficient to lift the band 11 away from the periphery of the casting wheel 10 and to permit ingress of the fluid into the interior of the mold.
The cooling manifold 13 is positioned along the arcuate length of the mold such that the stream of cooling liquid from the first spray nozzle 12' impinges at or after a point on the band 11 which corresponds to the end of the second phase of solidification of the cast bar. This point is illustrated in FIG. 4 as being at about the three o'clock position on the mold; however, the exact location of this point will, of course, vary with the casting rate. At fast casting rates, or at slow cooling rates, the point would occur much later along the arcuate length of the mold. Since it is desirable that the thickness of the soldified crust be about at least 1/4 inch at the point of the first water impingement, it is advantageous to provide a means (not shown) for selecting which of the nozzles 12 will be the first operable spray nozzle 12'. Such means could be either valves between the nozzles and the manifold or simply means for moving the entire manifold 13 along the arcuate path of the mold.
It is not necessary that the first nozzle 12' be exactly at the point of the end of the second phase of solidification since only a small decrease in the cooling rate is experienced when the point of impingement is later, i.e., at the beginning of phase three of soldification. It is, however, absolutely necessary to avoid spraying water into the mold during the first phase of solidification where the cast metal is still molten, inasmuch as this might lead to violent explosions.
As seen most clearly in FIGS. 2 and 3, the peripheral edges of the casting wheel 10 are preferably chamfered so that a wedge-shaped interface area 15 extends peripherally about the arcuate mold between the band 11 and the peripheral edge of the casting wheel 10. During the third stage of solidification, high pressure jets of coolant are emitted from the nozzles 12 toward the wedge-shaped interface 15 and of a magnitude sufficient to lift the band 11 away from the periphery of the casting wheel 10. If the fluid jets are directed only at one edge or marginal zone of the band 11, in accordance with the preferred embodiment of the invention, rather than at both edges of the band 11, the band 11 will become skewed or inclined with respect to the periphery of the wheel 10 as seen in FIG. 3. Thus, the fluid jets will deflect off of the band 11 and readily enter the interior of the mold; however, at the opposite side of the mold the band 11 will be urged more closely into sealing engagement with the periphery of the wheel 10, thus inhibiting egress of the fluid therefrom. It should be apparent, therefore, that the fluid will build-up in the interior of the mold, and vaporize therein under the heat of the casting operation. Consequently, this fluid pressure will exert a force on the bandside surface of the cast bar and force the bar into contact with the wall surfaces of the peripheral groove. It should be apparent that the coolant fluid, e.g., water, both directly cools the band-side surface of the cast bar, and generates steam which forces the bar into contact with the wall surfaces of the casting groove, thus increasing the conduction heat transer therebetween.
In contra-distinction to prior art systems, wherein the cast bar is permitted to fall downwardly out of the casting groove so that the cooling fluid is permitted to entirely engulf the bar, the cast bar in the present invention is not permitted to fall downwardly out of the mold but rather is pressed firmly into the mold thereby providing firm support for the same and preventing cracking and deformation of the bar.
Furthermore, as seen most clearly in FIG. 6, the fluid jets emitted from the nozzles 12 operate only on a given segment of the band 11 along a portion of the arcuate mold. Thus, the band 11 is maintained in sealing contact with the periphery of the wheel 11 along substantial arcuate segments extending inwardly from both the inlet and outlet of the mold. Because of this construction and arrangement, the cast bar is further firmly supported in the casting mold.
The relative cooling rate improvement due to this invention is diagrammed in FIG. 5 which shows the heat transfer rates during the three phases of solidification of a typical cast metal. In this invention and in the prior art methods of cooling, the heat transfer rates during phase 1 and 2 are essentially the same. However, during phase 3, the prior art methods experience a drastic reduction of heat transfer due to the shrinkage gap formation. With this invention the heat transfer rate during phase three is much improved due to the absence of any significant shrinkage gap. Therefore, less dwell time for the metal in the third phase of solidification is needed to fully solidify the cast metal. This allows an increase in the overall casting rate since the rotational speed of the wheel can be increased as the required dwell time is decreased.
After the metal passes through this zone of increased cooling the band 11 resumes contact with the casting wheel 10 and the bar is extracted from the casting wheel in the usual manner to be passed on to subsequent processing equipment such as a rolling mill, for example.
OPERATION
In operation of the apparatus and in practicing the method of this invention, the casting apparatus is started in the usual manner by rotating the casting wheel 10 with a conventional power means, not shown, and the band 11 is positioned against the casting wheel 10, to form the mold, by presser wheel 14. The pouring pot 26 directs molten metal into the mold and the metal begins to solidify as a result of cooling of the wheel and band by conventional interior and exterior spray assemblies, not shown. As the molten metal moves with the mold, it is cooled sufficiently during its first solidification phase to start partial solidification of the metal. This forms a crust of metal adjacent the sides of the mold while the metal in the center of the mold is still liquid and unsolidified. This crust continues to thicken during the second solidification phase and the rotational speed of the casting wheel is such that by the time the metal has reached the end of phase two, the crust enclosing the molten center is sufficiently thick to support the molten metal without collapsing. Depending on the rotational speed of casting wheel 10, cooling manifolds 13 are positioned, as explained previously, so that water is sprayed into the wheel-band interface thereby lifting the band 11 from contact with the wheel 10 and exposing the semi-solid cast bar to the cooling water. Since the cooling manifolds 13 are flexibly connected to the main coolant supply, their positions can be varied depending upon the particular point on the casting wheel at which the third phase of solidification begins for each particular casting rate. The third phase of solidification begins when the crust of solidified metal becomes sufficiently thick so that the cast bar shrinks away from the mold walls. The gap G formed between the mold and the solidified metal crust C greatly reduces the rate at which heat is transferred from the bar to the mold during the third phase. This is shown by the diagram of FIG. 5 wherein the rate of heat transfer of the mold during solidification of the metal in a prior art system is indicated by the dashed line. The greatly reduced cooling rate during the third phase of solidification, characteristic of prior art cooling systems, limits the maximum rotational speed of the casting wheel so that speed which insures that sufficient solidification of cast bar C takes place while the bar is within the peripheral groove of the casting wheel. Again referring to FIG. 5, it can be seen that the cooling rate obtained when practicing the improved cooling method and apparatus of this invention is much greater, as illustrated by the solid line, during the third phase of solidification due to the elimination of the gap between the wheel 10 and the hot cast bar C. Thus it should now be understood that the invention requires the operation of the casting machine at a rotational speed which will result in the metal passing into this area of increased cooling at the beginning of, or early in, the third solidification phase. It will also be understood that this requirement depends upon the exact placement of the cooling manifold 13 but in any event provides greater casting rates than were possible with prior art cooling methods. It will also be noted that the molten metal is poured into the arcuate mold at a high level on one side of the casting wheel 10 and is completely solidified before the molten core reaches a corresponding level on the opposite side of the casting wheel. Thus the molten core is always maintained under a high hydrostatic pressure, which is effectice to reduce the frequency of voids or cavities appearing in the cast bar.
Although a specific embodiment of the invention has been disclosed herein in illustrating the invention, it is to be understood that the inventive concept is not limited thereto since it may be embodied in the other arrangements or devices in which coolant fluid is used to force the bar firmly into the wheel, without departing from the scope of this invention as set forth in the appended claims. However, the apparatus disclosed herein is a particularly suitable arrangement.
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An improved cooling method and apparatus for a continuous casting process of the type wherein the mold is a rotatable casting wheel having a peripheral groove with a portion enclosed by an endless band. The improved cooling of the hot cast metal bar is accomplished by injecting a cooling fluid, under pressure, into the shrinkage gap between the hot continuously cast bar and the band portion of the mold after the bar is partially solidified but before it is removed from the wheel portion of the mold. The hydraulic pressure of the cooling fluid forces the band portion of the mold away from the periphery of the casting wheel so as to allow a quantity of cooling fluid to impinge directly on the hot but solidified band-side surface of the cast bar to directly cool the bar, and also to permit a build-up of fluid pressure in the mold which forces the bar firmly into contact with the walls of the peripheral groove and thus eliminates any shrinkage gap therebetween, thereby increasing the quantity of heat transferred from the hot cast bar.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national stage application, under 35 U.S.C. §371, of PCT/EP2005/008441 filed Aug. 4, 2005, which claims benefit of German Application No. 10 2004 042 453.5 filed Aug. 31, 2004.
BACKGROUND OF THE INVENTION
Important fields of use of triethanolamine (TEOA) or its secondary products are, for example, soaps, detergents and shampoos in the cosmetics industry and also dispersants and emulsifiers.
For these and other fields of use, water-clear, colorless triethanolamine with the slightest possible discoloration, e.g. measured as APHA or Gardner color number, which retains these properties even over prolonged storage periods (of e.g. 6, 12 or more months) is desired.
A known problem is that a pure TEOA obtained by fractional distillation of a triethanolamine crude product which has been obtained, for example, by reacting ammonia with ethylene oxide has a yellowish to brownish or pink discoloration (color number e.g. about 10 to 500 APHA in accordance with DIN ISO 6271 (=Hazen)). This discoloration arises particularly in processes in which high temperatures are passed through.
During storage of the alkanolamine, even in a sealed pack and with the exclusion of light, this discoloration is further intensified. (See e.g.: T. I. MacMillan, Ethylene Oxide Derivatives, report No. 193, chapter 6, pages 6-5 and 6-9 to 6-13, 1991, SRI International, Menlo Park, Calif. 94025;
G. G. Smirnova et al., J. of Applied Chemistry of the USSR 61, pp. 1508-9 (1988), and Chemical & Engineering News 1996, Sep. 16, page 42, middle column).
The literature describes various methods of producing triethanolamine with improved color quality.
EP-A-36 152 and EP-A-4015 (both BASF AG) explain the influence of the materials used in methods of producing alkanolamines on the color quality of the process product and recommend nickel-free and/or low-nickel steels.
U.S. Pat. No. 3,207,790 (Dow Chemical Company) describes a method of improving the color quality of alkanolamines by adding a boron hydride of an alkali metal.
EP-A-1 081 130 (BASF AG) relates to a method of producing alkanolamines with improved color quality by treating the alkanolamine with hydrogen in the presence of a hydrogenation catalyst.
EP-A-4015 (BASF AG) describes that mono-, di- and triethanolamine with less discoloration are obtained by adding phosphorous or hypophosphorous acid or derivatives thereof before or during or directly after the stepwise reaction of ethylene oxide with ammonia and subsequent isolation by distillation.
WO-A-00/32553 (BASF AG) relates to a method of purifying TEOA produced by the reaction of aqueous ammonia with ethylene oxide in liquid phase under pressure and at elevated temperature by separating off excess ammonia, water and monoethanolamine from the reaction product, reacting the crude product obtained in this way with ethylene oxide and then rectifying it in the presence of phosphorous or hypophosphorous acid or compounds thereof.
EP-A-1 132 371 (BASF AG) relates to a method of producing alkanolamines with improved color quality where the alkanolamine is treated with an effective amount of phosphorous or hypophosphorous acid or compounds thereof firstly at elevated temperature over a period of at least 5 min (step a) and is then distilled in the presence of an effective amount of one of these phosphorous compounds (step b).
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a method of producing triethanolamine and triethanolamine comprising phosphorous and/or hypophosphorous acid and certain basic compounds.
The object of the present invention was to provide a method of producing triethanolamine with good color quality which is improved compared with the prior art. The method is intended to reduce the discoloration of TEOA, e.g. measured as APHA color number, and improve the color stability (undesired increase in the color number over the storage period). In particular, the method was to produce higher yields of TEOA compared with EP-A-4015, WO-A-00/32553 and EP-A-1 132 371.
Accordingly, a method of producing triethanolamine has been found wherein phosphorous and/or hypophosphorous acid and a basic compound chosen from alkali metal hydroxide, alkaline earth metal hydroxide and [R 1 R 2 R 3 (2-hydroxyethyl)-ammonium] hydroxide, where R 1 , R 2 and R 3 , independently of one another, are C 1-30 alkylor C 2-10 -hydroxyalkyl, are added to the triethanolamine and in the case of alkali metal hydroxide as basic compound the molar ratio of acid(s):hydroxide is in the range from 1:0.1 to 1:1 and in the case of alkaline earth metal hydroxide as basic compound the molar ratio of acid(s):hydroxide is in the range from 1:0.05 to 1:0.5.
In addition triethanolamine comprising phosphorous and/or hypophosphorous acid and R 1 R 2 R 3 (2-hydroxyethyl)ammonium] hydroxide, where R 1 , R 2 and R 3 , independently of one another, are C 1-30 -alkyl or C 2-10 -hydroxyalkyl, has been found.
In addition, triethanolamine comprising phosphorous and/or hypophosphorous acid and an alkali metal hydroxide or alkaline earth metal hydroxide, where in the case of alkali metal hydroxide the molar ratio of acid(s):hydroxide is in the range from 1:0.1 to 1:1 and in the case of alkaline earth metal hydroxide the molar ratio of acid(s):hydroxide is in the range from 1:0.05 to 1:0.5, has been found.
Preferred molar ratios of acid(s):hydroxide in the triethanolamine are given in the description below.
According to the invention, it has been recognized that while retaining or even improving the color quality compared with the sole use of H 3 PO 3 or H 3 PO 2 , the formation of by-products in the TEOA is significantly reduced as a result of the additional basic compound (buffer effect of the base). At the same time, the TEOA distillation yield is increased. The by-product formation is presumably based on the acidic effect of the phosphorous compounds.
DETAILED DESCRIPTION OF THE INVENTION
The triethanolamine used in the method according to the invention can be obtained by known methods, in particular by reacting ammonia with ethylene oxide (e.g. as in EP-A-673 920 or WO-A-00/32553).
The purity of the triethanolamine used in the method according to the invention is preferably greater than 70% by weight, in particular greater than 80% by weight. Besides distilled or undistilled crude triethanolamine, which can also be removed directly in crude form from a plant for producing alkanolamine from the corresponding precursors, it is also possible to use distilled TEOA with a purity of greater than 90% by weight, e.g. greater than 95% by weight, particularly ≧97% by weight, in particular ≧98% by weight, very particularly ≧99% by weight.
It is also possible to use mixtures of triethanolamine with other alkanolamines, such as, for example, monoethanolamine (MEA), diethanolamine (DEA), aminodiglycol (ADG, H 2 NCH 2 CH 2 OCH 2 CH 2 OH), O,N,N-tris(2-hydroxyethyl)ethanolamine, N-(2-aminoethyl)-ethanolamine (AEEA), N-(2-hydroxyethyl)piperazine, N-(2-hydroxyethyl)morpholine, N,N′-bis(2-hydroxyethyl)piperazine, monoisopropanolamine, diisopropanolamine, triisopropanolamine and 1,3-propanolamine, or solutions of triethanolamine in an inert solvent, such as, for example, alcohols (methanol, ethanol, isopropanol, n-propanol, n-butanol, 2-ethylhexanol), ethers (tetrahydrofuran, 1,4-dioxane), hydrocarbons (benzene, pentane, petroleum ether, toluene, xylene, hexane, heptane, mihagol) and water or mixtures thereof.
The APHA color number of the triethanolamine used is preferably ≦100, in particular ≦50, very particularly ≦20.
The method according to the invention can be carried out as follows:
In a suitable container, e.g. stirred container, which may be equipped with a reflux condenser, an effective amount of phosphorous acid (H 3 PO 3 ) and/or hypophosphorous acid (H 3 PO 2 ) and a basic compound chosen from alkali metal hydroxide, alkaline earth metal hydroxide and [R 1 R 2 R 3 (2-hydroxyethyl)ammonium] hydroxide, where R 1 , R 2 and R 3 have the meanings given, are added to the triethanolamine whose color quality is to be improved in liquid phase, optionally in the presence of an inert solvent, advantageously with stirring or circulation pumping.
The mixture is heated over a period of preferably at least 5 min, in particular at least 10 min (for example 10 min to 50 hours, in particular 10 min to 24 hours), very particularly at least 15 min (for example 15 min to 6 hours), particularly preferably at least 30 min (for example 30 min to 4 hours or 40 min to 3 hours or 60 min to 2 hours) at a temperature in the range from 40 to 250° C., in particular 100 to 240° C., very particularly 120 to 230° C., particularly preferably 150 to 220° C.
The phosphorous acid and/or hypophosphorous acid can be used in the method according to the invention in monomeric or polymeric form, in hydrous form (hydrates or aqueous solution or aqueous suspension) or as addition compound (e.g. on an inorganic or organic support such as SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 ).
The amount of added acid(s) is generally at least 0.01% by weight, preferably 0.02 to 2% by weight, particularly preferably 0.03 to 1.0% by weight, very particularly preferably 0.5 to 0.9% by weight, based on the amount of triethanolamine used (calculated on the basis of pure substances); however, the effect also arises with relatively large amounts.
If phosphorous acid and hypophosphorous acid are used together, the above quantitative data refer to both acids together.
In the method according to the invention the basic compound which can be used is an alkali metal hydroxide, where alkali metal=Li, Na, K, Rb or Cs, preferably Na or K, an alkaline earth metal hydroxide, where alkaline earth metal=Be, Mg, Ca, Sr, Ba, or preferably an ammonium hydroxide of the formula [R 1 R 2 R 3 (2-hydroxyethyl)ammonium] hydroxide, i.e.
The radicals R 1 , R 2 and R 3 , independently of one another, have the following meanings:
unbranched or branched C 1-30 -alkyl, among them C 8-22 -alkyl, preferably C 1-20 -alkyl, in particular C 1-14 -alkyl, among them C 1-4 -alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, n-hexyl, isohexyl, sec-hexyl, cyclopentylmethyl, n-heptyl, isoheptyl, cyclohexylmethyl, n-octyl, isooctyl, 2-ethylhexyl, n-decyl, 2-n-propyl-n-heptyl, n-undecyl, n-dodecyl, n-tridecyl, 2-n-butyl-n-nonyl, 3-n-butyl-n-nonyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-octadecyl,
C 2-10 -hydroxyalkyl, preferably C 2-8 -hydroxyalkyl, particularly preferably C 2-4 -hydroxyalkyl, such as 2-hydroxyethyl, 2-hydroxy-n-propyl, 3-hydroxy-n-propyl and 1-(hydroxymethyl)ethyl, particularly preferably 2-hydroxyethyl.
These 2-(hydroxyethyl)ammonium hydroxides are accessible to the person skilled in the art by known processes. In particular, they are accessible by the reaction of the corresponding tertiary amine R 1 R 2 R 3 N (e.g. Et 3 N, fatty amine, TEOA) with one mole equivalent of ethylene oxide and water.
Compare for [tetrakis(2-hydroxyethyl)ammonium] hydroxide e.g.: A. R. Doumaux et al. J. Org. Chem. 1973, 38 (20), pages 3630-3632, and DE-A-22 17 494 and DE-A-21 21 325 (both BASF AG).
One advantage of the ammonium hydroxide is that the quaternary ammonium salt dissolves completely in the triethanolamine mixture and at least partially neutralizes the H 3 PO 3 and/or H 3 PO 2 (buffer effect).
Particularly preferred ammonium hydroxides are [tetrakis(2-hydroxyethyl)ammonium] hydroxide and [(C 1-4 -alkyl) 3 (2-hydroxyethyl)ammonium] hydroxide, such as, for example, [triethyl(2-hydroxyethyl)ammonium] hydroxide.
A further advantage of the particularly preferred [tetrakis(2-hydroxyethyl)ammonium] hydroxide arises from the fact that, under the conditions of the triethanolamine distillation, the base decomposes partially or completely to give water and the product of value triethanolamine and therefore does not need to be separated off from the product of value. No problems resulting from salt formation arise.
A further advantage of a (2-hydroxyethyl)ammonium hydroxide based on a fatty amine ((C 8-30 ) 3 N) is the fact that, under the conditions of the triethanolamine distillation, the base partially or completely decomposes to give water and the fatty amine and the fatty amine can easily be separated off from the pure TEOA via the distillation bottoms as a high-boiling component.
Preferably, the molar ratio of acid(s) used to ammonium hydroxide used is 1:1 to 100:1, particularly 1.1:1 to 10:1, in particular 1.2:1 to 8:1, very particularly 1.3:1 to 6:1.
In the case of alkali metal hydroxide as basic compound, the molar ratio of acid(s):hydroxide is preferably in the range from 1:0.2 to 1:0.9, in particular 1:0.3 to 1:0.8, very particularly 1:0.4 to 1:0.7, e.g. 1:0.5 to 1:0.6.
In the case of alkaline earth metal hydroxide as basic compound, the molar ratio of acid(s):hydroxide is preferably in the range from 1:0.1 to 1:0.45, in particular 1:0.15 to 1:0.4, very particularly 1:0.2 to 1:0.35.
If phosphorous acid and hypophosphorous acid are used together, the above molar ratio data refer to both acids together.
For example, 1000 ppm of H 3 PO 3 and between 320 and 2573 ppm of the basic compound [tetrakis(2-hydroxyethyl)ammonium] hydroxide are added to the TEOA.
The basic compound can firstly be added to the TEOA, followed by the acid(s). In a preferred procedure, the acid(s) is/are firstly added to the TEOA and then the basic compound is added.
In another preferred procedure, a mixture of the acid(s) with the basic compound is firstly prepared and this mixture is then added to the TEOA.
In order to improve the handling properties it may be advantageous here to meter in the effective amount of phosphorous acid and/or hypophosphorous acid in a suitable inert diluent or solvent, such as, for example, water, alcohols (methanol, ethanol, isopropanol, n-propanol, n-butanol, 2-butanol), ethers (tetrahydrofuran, 1,4-dioxane) or an alkanolamine (e. g. an ethanolamine, such as monoethanolamine, diethanolamine, N-(2-aminoethyl)ethanolamine, in particular triethanolamine), in the form of a solution or a suspension.
The basic compound can advantageously be used as a solution or suspension in water, e.g. as a 30 to 80% strength by weight, in particular 40 to 60% strength by weight, solution or suspension.
[Tetrakis(2-hydroxyethyl)ammonium] hydroxide is commercially available in the form of a 50% strength by weight aqueous solution and it can be used advantageously.
The required treatment time of the triethanolamine with the addition of acid and basic compound arises inter alia from the degree of discoloration of the triethanolamine used and the extent of desired decoloration and/or color stability of the TEOA. For a given temperature the higher the degree of discoloration of the triethanolamine used in the process according to the invention and the higher the requirements placed on the color quality of the process product, the greater the time.
The temperature must, however, not be chosen to be too high, i.e. generally not higher than 250° C. since otherwise an acid-induced degradation of the triethanolamine can take place which adversely affects the color quality of the TEOA ultimately obtained. The temperatures and treatment times which are most favorable for the particular triethanolamine used are easy to ascertain in simple preliminary experiments.
During this treatment of the triethanolamine with the acid and the basic compound it is advantageous if the mixture is further mixed (e.g. stirred or circulated by pump) throughout the entire treatment time or at intervals.
It is also advantageous if the treatment of the triethanolamine is carried out under a protective gas atmosphere (e.g. N 2 or Ar), i.e. in the absence of O 2 .
The treatment of the alkanolamine with the acid and the basic compound can also be carried out continuously in suitable containers, e.g. in a tubular reactor or in a cascade of stirred containers.
The treatment of the triethanolamine with the acid and the basic compound can be carried out advantageously in the bottoms container of a distillation column or in a distillation initial charge vessel before and/or during the distillation of the triethanolamine.
In a particular embodiment during the treatment of the triethanolamine with the acid and the basic compound an inert gas (e.g. N 2 or Ar) is passed as a stripping stream through the triethanolamine in order to remove from the mixture any low-boiling components which form and which can have an adverse effect on the color quality, such as, for example, acetaldehyde or secondary products thereof.
In another particular embodiment, the triethanolamine to be treated is circulated in liquid form via a heat exchanger and any low-boiling components which form, which can have an adverse effect on the color quality, such as, for example, acetaldehyde, are removed in the process.
The heat exchanger here may be an open heat exchanger, such as, for example, a falling-film or wiper-blade evaporator, or a sealed heat exchanger, such as, for example, a plate- or tube-bundle heat exchanger.
Depending on the reaction conditions chosen, it may be necessary to carry out the treatment of the triethanolamine with the acid and the basic compound at a superatmospheric pressure (e.g. 0.1 to 50 bar) in order to avoid the undesired escape of one or more components from the mixture.
The distillation or rectification of the triethanolamine to separate off the added compounds takes place discontinuously or continuously at a pressure of usually less than 100 mbar (100 hPa), for example at about 10 to 50 mbar or 1 to 20 mbar, preferably at 0.5 to 5 mbar, and at bottoms temperatures of generally 100 to 250° C., where in the case of the continuous procedure, in a particular embodiment, any low-boiling component fractions present are drawn off overhead and the TEOA is obtained in the side take-off.
The residue of the distillation or rectification comprising the added compounds and/or reaction products thereof can, in a particular embodiment, be completely or partially returned to the distillation process.
The method according to the invention produces a triethanolamine with improved color quality which, directly after being obtained, has a APHA color number in the range from 0 to 30, in particular from 0 to 20, very particularly from 0 to 10, e.g. 1 to 6.
All of the APHA data in this document are in accordance with DIN ISO 6271 (=Hazen). All of the ppm data in this document are based on the weight (ppm by weight).
EXAMPLES
The experiments were carried out in a laboratory apparatus consisting of a 4 liter three-necked flask with stirrer, thermometer and gas line. 1000 ppm of H 3 PO 3 were added to a mixture of 21% by weight of diethanolamine and 79% by weight of triethanolamine and in each case varying amounts of a base, as desired.
Under reduced pressure at a bottoms temperature of about 190-195° C., diethanolamine and triethanolamine were distilled off from the flask one after the other over a period in the range from 1 to 8 h via a Vigreux column and fractions of triethanolamine with a content of at least 99.4% (GC area %) were obtained.
Color number measurements (according to Hazen) were carried out on these triethanolamine grades and documented in the table below. The yield losses as a result of secondary reactions were determined by weighing out the fractions of diethanolamine and triethanolamine (TEOA) obtained and are based on the formation of high-boiling compounds which are left behind in the bottoms following distillation.
TABLE 1
Content
Color
Amount of
Type, amount of
Base/H 3 PO 3
of TEOA
number
bottoms residue
additive (ppm)
(molar ratio)
GC area %
(Hazen)
(% by weight)
H 3 PO 3 , 1000
0
99.6
5
5.0
H 3 PO 3 , 1000/
⅛
99.5
2
2.2
Base, 320
H 3 PO 3 , 1000/
¼
99.7
5
4.2
Base, 645
H 3 PO 3 , 1000/
½
99.5
3
1.1
Base, 1290
Base = [tetrakis(2-hydroxyethyl)ammonium]hydroxide
The additional addition of the ammonium hydroxide to the phosphorous acid brings about an increase in the distillation yield of triethanolamine without having an adverse effect on the color number, and sometimes even having a positive effect on the color number (in the sense of reducing the color number).
TABLE 2
NaOH/
Content
Color
Amount of
Type, amount of
H 3 PO 3
of TEOA
number
bottoms residue
additive (ppm)
(molar ratio)
(GC area %)
(Hazen)
(% by weight)
H 3 PO 3 , 1000/
1.0
99.8
3
2.0
NaOH, 490
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Methods for improving color properties of triethanolamine, and triethanolamine compositions treated thereby, are disclosed, wherein the methods comprise: (a) providing a composition comprising triethanolamine; and (b) contacting the composition with an acid component and a basic component; wherein the acid component comprises an acid selected from the group consisting of phosphorous acid, hypophosphorous acid and mixtures thereof; and wherein the basic component comprises a compound selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxides according to general formula (I), and mixtures thereof:
[R 1 R 2 R 3 (2-hydroxyethyl)ammonium] hydroxide (I)
wherein R 1 , R 2 and R 3 each independently represents a C 1-30 alkyl or a C 2-10 hydroxyalkyl; with the proviso that where the basic component comprises an alkali metal hydroxide, the molar ratio of acid component: basic component is 1:0.1 to 1:1, and where the basic component comprises an alkaline earth metal hydroxide, the molar ratio of acid component: basic component is 1:0.05 to 1:0.5.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to disc-type valves used in the flow lines for fluid material to commence or halt the flow of such materials.
2. Description of the Prior Art
Disc-type valves are heretofore known have several problems. In disc-type valves, such as the known three-lever valves, the movement of the disc is such that it begins to pivot almost immediately as force is applied through the lever linkage. This pivotal motion causes the disc to slide across the surface of the valve seat in an abrasive fashion resulting in a scratched and abraded valve seat. Once the valve seat loses it original smooth finish, the ability of the valve to halt the flow of fluids is significantly reduced.
Due to the pressure differential encountered in closing the disc of a disc-type three lever valve, there exists in known valves of this type, a leakage problem caused by the force of flowing material through the valve, preventing the disc from fully seating itself against the valve seat.
All of the known butterfly valves encounter fluctuations in the rate and direction of flow of materials through them. In addition, various impurities of a physical quality different from that of the intended material, flow through the valve. The result is a tendency to cause the valve disc to flutter about its pivotal axis. Such flutter augments the fluctuation of flow and can cause the valve to partially close at an inopportune time.
In accordance with this invention, there is provided control of the motion of the valve disc such (a) that it is positively pulled away from the valve seat before it is pivoted, thus eliminating the sliding motion of the disc across the seat; (b) that it is closed through a positive means which insures full contact of the valve disc periphery against the valve seat upon closure of the valve; and (c) that it is held immobile in its open position despite the flow of fluid past the disc.
SUMMARY OF THE INVENTION
The present invention is directed primarily to an improvement in the means for operating a disc-type valve by a specific arrangement of levers and guides which operate in conjunction with each other to produce a distinct linear movement of the valve disc in relation to the valve seat, and thereafter a pivoting movement of the disc, the linear motion being separate and non-concurrent from pivotation of the valve disc. All motions of the valve disc are positively directed and controlled by mechanical means and not dependent on operation of the forces of gravity. The points of connection of the levers to the valve disc and guides are arranged to lock the valve disc in position when the valve is open, to rock the valve disc against the valve seat during closure of the valve and to lock the valve in closed position.
Rotary force is directed through an eccentric which is linked to a valve disc. A pivot is also mounted on the valve disc to extend into guides. Within the guides, a leverage system directs and controls the motion of the valve disc. At the open and the closed position of the valve, the valve disc is locked in place. As the valve is closed, a hook fixed to the valve disc engages the link, connecting the eccentric to the disc, and shifts the point of force applied to the disc causing the disc to rock into place against the valve seat.
One of the principal features of this invention is the ability of the valve to be operated in any position, independent of the force of gravity.
Another principal feature of the current invention is the provision of a means by which damage to the valve seat can be avoided by eliminating the possibility of any sliding motion of the disc periphery across the plane of the valve seat as the valve is being opened and closed.
Another principal feature of the current invention is the provision of a means by which the valve disc is held rigidly when in the open position, eliminating flutter which causes significant fluctuation in the rate of material flow through the valve and also eliminating the possibility of unintended closure of the valve.
Another principal feature of the current invention is the provision of a means by which the valve disc can be positively closed against the valve seat so as to insure no leakage of the valve in operation.
These, and other features of this invention, will be more completely disclosed and described in the following detailed description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric perspective view of a preferred embodiment of the valve as viewed from the left rear corner, with a section of the valve body removed to reveal the internal positioning of the elements of the valve in a partially opened/closed position.
FIG. 2 is a rear sectional view of the valve of FIG. 1 in the closed position.
FIG. 3 is a sectional side view of the valve of FIG. 1 in the closed position.
FIG. 4 is an enlarged sectional side view of the left guide block with the valve of FIG. 1 in the closed position.
FIG. 5 is a sectional side view of the valve of FIG. 1 in the open position.
FIG. 6 is an enlarged sectional side view of the left guide block of FIG. 4 with the valve in the open position.
FIG. 7 is a rear sectional view of the left guide block of FIG. 6 with the valve in the closed position.
FIG. 8 is an enlarged sectional view of the hook member and link member, with the valve in the closed position, detailing a preferred embodiment of the pivotal connection of the link member to the valve disc.
FIG. 9 is an enlarged sectional view of the hook member and the link member, with the valve in the closed position, detailing an alternate embodiment of the pivotal connection of the link member to the valve disc.
DETAILED DESCRIPTION
Referring to FIG. 1 of the drawings, there is illustrated a valve body 11 that includes as an integral part thereof a valve seat 13. In accordance with the preferred embodiment, a crankshaft 14 is transversely positioned within the valve body 11 above the central axis of the valve body. The crankshaft 14 is mounted so as to allow it to be rotated about its axis by any one of many commercially available means of producing rotary motion, such as a gear reduced motor, generally designated by the numeral 15. The means of producing rotary motion 15 is such that when not activated, the crankshaft 14 is prevented from rotating.
The torque force resulting from the rotation of the crankshaft 14 is transmitted to an eccentric which is illustrated as a crank lever 16 fixed to the crankshaft 14 within the valve body 11. The free end of the crank lever 16 is pivotally connected, for example by a bolt, to a link member 17. The link member 17 is also pivotally coupled to a valve disc 18 at a point displaced from, i.e. below, the central axis of the valve disc 18. Fixed about the periphery of the valve disc 18 is a valve seal 19 made of a material suitable to mate with the valve seat 13 upon pressurized contact.
The link member 17 is pivotally coupled to the valve disc 18 by a cylindrical fastener 20, such as a bolt, placed through a corresponding hole through the link member and an adjacent slot in a lug 21 fixed to the valve disc 18, as illustrated in FIG. 8.
The length of the slot 21 is between one and one-quarter and one and one-half times the diameter of the cylindrical fastener 20, and its width is large enough to allow the cylindrical fastener 20 to move laterally within the slot. The play between the cylindrical fastener 20 and the slot enables the disc to rock before engaging the valve seat 13 so that full peripheral contact of the valve disc 18 with the valve seat 13 is achieved. The lug 21 is positioned such that when the valve disc 18 is in its closed position, as illustrated in FIG. 3, the linear direction of the slot is aligned with, and parallel to, the centerline of the link member, drawn between the cylindrical fastener 20 and the point of pivotal connection of the crank lever with the link member 17.
An alternate embodiment of a means for pivotally coupling the link member 17 to the valve disc 18 is illustrated in FIG. 9. A lug 38, containing a circular hole, replaces the lug 21 which contains a slot. An eccentric member 39 is rotatably mounted in the circular hole of the lug 38. The eccentric member 39 is in the form of a portion of a circle, with an arc of greater than 180°, bisected by a secant which forms a flat edge on the circle, as illustrated in FIG. 9. The eccentric member 39, in place in the lug 38, does not fill the circular hole in the lug 38. A key 40 is fixed within the circular hole in the lug 39 as illustrated in FIG. 9. The key 40 serves as a stop to limit the rotation of the eccentric member 39, within the lug 38, to a pre-set arc. A cylindrical fastener 41 is fixed to the apex of the arc of the eccentric member 39, opposite to the flat edge of the eccentric member 39, and projecting perpendicular to the face of the eccentric member 39. The link member 17 is pivotally connected to the cylindrical fastener 41. Rotation of the eccentric member 39 within its pre-set arc produces a rocking motion of the valve disc 18 in relation to the link member 17.
Force is initially applied to the valve disc 18 through a hooked member 22, as illustrated in FIGS. 1, 3, 5 and 8, which is fixed about the center of the valve disc 18. A hook pin 25 is fixed to the link member 17 and positioned so that the hook pin 25 engages the eye 24 of the hooked member 22 when the valve disc 18 is in the closed position, as illustrated in FIG. 8. The hook pin 25 is positioned along the central axis of the valve body 11 when the valve disc 18 is in the closed position, as illustrated in FIG. 3. Force from the crank lever 16 is directed through the link member 17 to the hook pin 25 to the eye 24 and, in turn, the hooked member 22 to the valve disc 18, in that position.
Two stub shafts 26 are symetrically fixed on a common axis running across the surface of the valve disc 18, as illustrated in FIGS. 1 and 2. Each stub shaft end 27 extends beyond the periphery of the valve disc 18 into a corresponding guide block 28 which is fixed to the valve body wall 12 on opposite sides of the valve body 11, as illustrated in FIGS. 1 and 7.
Each of the guide blocks 28 is comprised of a housing 29 into which is fitted, firstly, a guide track 31 and, secondly, superimposed on the guide track 31, a roller way 35. A cover 30 is placed over the guide block 28 to seal it, as illustrated in FIGS. 1 and 7. In each guide block 28, the corresponding stub shaft end 27 extends into the guide track 31, as illustrated in FIG. 7. A roller lever 36 is fixed to the outboard end of each stub shaft end 27, as illustrated in FIGS. 1, 4, 6 and 7, and positioned so as to allow it to move freely within a space between the guide track 31 and roller way 35, as illustrated in FIG. 7. A roller 37 is fixed to the free end of each roller lever 36 and positioned so as to ride in a roller way 35, as illustrated in FIGS. 4, 6 and 7.
Each of the guide tracks 31 contains a linear slot, as illustrated in FIGS. 4 and 6, the slot being directed from its initial end A horizontally to its terminal end B where it changes direction downward at an oblique included angle, as illustrated in FIGS. 4 and 6. The width of each slot in the guide tracks 31 is great enough to accommodate lateral motion of a stub shaft end 27 positioned in the slot, as illustrated in FIG. 7.
Each of the roller ways 35 also contains a linear slot, as illustrated in FIGS. 4 and 6, and, like the guide tracks 31, the slot is directed horizontally to a point where it changes direction. However, unlike slots in the guide tracks 31, the slots in the roller ways 35 change direction upward at an oblique included angle, as illustrated in FIGS. 4 and 6. The width of each slot in the roller way 35 is great enough to accommodate a roller 37, as illustrated in FIG. 7.
The positioning of each roller way 35 as superimposed on a guide track 31, as illustrated in FIG. 4 and FIG. 6, is such that their respective slots form a fork or wishbone pattern.
In FIG. 1, the valve is shown as being in a closed position; the valve disc 18 has its seal 19 fully and positively engaged with seat 13. The valve is opened by activation of the means 15 for producing rotary motion which, as illustrated, rotates the crankshaft 14 a counterclockwise direction, which, in turn, moves the crank lever 16 in a direction away from the valve seat 13. The motion of the crank lever 16 applies directional force to the link member 17 which, in turn, at that instant applies directional force to the hook pin 25, through the hook member 22, to the center point of the valve disc 18 causing seal 19 to move away from the valve seat 13. The direction of the motion of the valve disc 18 away from the valve seat 13 is controlled by the engagement and interaction of the stub shaft ends 27 with the guide blocks 28. As the valve disc 18 is moved away from the valve seat 13, the motion of the valve disc 18 is, initially, positively linearly directed axially as the stub shaft ends 27 move in the guide tracks 31 along the central axis of the valve body 11, these guide tracks being perpendicular to the axis of the stub shafts 26. Initially, each roller lever 36, fixed to the stub shaft end 27, forces a roller 37, linearly directed by the slot in the roller way 35, in the same direction in which the valve disc 18 is moving, thus preventing any pivotation of the valve disc 18. However, when the rollers 37 reach the point A, the slots in the roller ways 35 are angularly redirected. As a result of the longitudinal alignment of each roller 37 with its corresponding roller way 35, the rollers move in the same line of direction at the point C where the roller 37 passes the point at which the slot in the roller way 35 is angularly redirected, the roller 37, directing the roller lever 36, is forced into the upward angle of the roller way 35, forcing the roller lever 36 to commence rotation of the stub shafts 26, about their common axis, as the valve disc 18 is further moved away from the valve seat 13. This causes the valve disc 18 to begin to pivot.
The pivotation of valve disc 18 causes the hook member 22 to disengage the hook pin 25 and this disengagement shifts the applied directional force from the center of the valve disc 18 to the point, below center of the valve disc 18, where the lug 21 is positioned, as illustrated in FIGS. 1, 3, 5 and 8. The cylindrical fastener 20 is forced to the point within the slot in the lug 21 furthest from the valve disc 18. The shift in the point of force applied to the valve disc 18 enhances the pivotation of the valve disc 18 about the axis of the stub shafts 26.
As the stub shaft 26 passes the terminal end B of the slot in the guide track 31, the stub shaft end 27 is forced into the downward angulation of the slot in the guide track 31, concurrent with pivotation of the valve disc 18. At a point where the valve disc 18 has pivoted 90° from its closed position, as shown in FIG. 3, to its fully open position, as shown in FIG. 5, the link members 17 encounter a stop 34, fixed to the crank lever 16, and all motion ceases.
In the open position, FIG. 5, the valve disc 18 is held rigidly in place. This rigidity is caused by halting the means of producing rotary motion 15 which, in turn, prevents rotation of the crankshaft 14 and thus rigidly positions the crank lever as illustrated in FIG. 5. Due to the position of the stop 34, the link member 17 is prevented from pivoting toward the valve seat 13. At this position of the link member 17, the cylindrical fastener remains positioned at the end of the slot in the lug 21 furthest from the valve disc 18, thus the valve disc is prevented from pivoting clockwise about the axis of the stub shafts 26, as illustrated in FIG. 5. FIG. 6 illustrates the position of the stub shaft end 27 in position in the corresponding guide track 31 when the valve disc 18 is in the open position. The valve disc 18 is prevented from pivoting about the stub shaft ends 27 by the position of the walls of the guide track 31 and the relation of the stub shaft end 27 to those walls as illustrated in FIG. 6. The valve disc 18 is prevented from moving further away from the valve seat 13 by the stub shaft ends 27 being positioned against the angled end of the guide tracks 31 as illustrated in FIG. 6.
Closure of the valve disc follows, generally, a reverse of the sequence of the steps of the opening procedure, commencing from the open position, as shown in FIGS. 5 and 6, and following in order until the valve disc is in position against the seat, as shown in FIG. 3. The direction of rotary force applied by the means of producing rotary motion 15 is reversed, i.e., now in a clockwise direction, from that of the opening cycle, thus urging the crankshaft 14 to rotate in a direction opposite to that of the opening cycle. The crank lever 16 commences movement in a clockwise direction. The link member 17 is forced downwardly from the position illustrated in FIG. 5 which in turn shifts the position of the cylindrical fastener 20 to a position of the slot in the lug 21 closest to the valve disc 18. This causes the valve disc 18, and thus the stub shaft ends 26, to move toward the valve seat 13. Concurrently, each roller lever 36 is oscillated as its roller 37 is drawn along the corresponding roller way 35 in a direction opposite to that of the opening cycle, causing the corresponding stub shaft 26 to be rotated, resulting in the pivotation of the valve disc 18 in a clockwise direction, opposite to that of the opening cycle. At the point where the valve disc 18 has been pivoted a full 90°, the hooked member 22, which is fixed in relation to the valve disc 18, re-engages the hook pin 25 as the link member 17 is pivoted about the cylindrical fastener 20 engaged with the lug 21. This causes the cylindrical fastener 20 to shift within the slot in the lug 21 resulting in the force directed to the valve disc 18 to be transmitted through the hooked member 22 to the center of the valve disc 18 and removing the point of force on the valve disc 18 from the pivotal coupling of the link members 17 to the valve disc 18.
The simultaneous engagement of the hooked member 22 with the hook pin 25 and the transfer of points of force causes the lug 21 to be moved, along its slot, in relation to the cylindrical fastener 20, resulting in a rocking of the valve disc 18, just prior to its coming into contact with the valve seat 13, thus disposing the valve disc 18 parallel to the valve seat 13 such that full peripheral contact of the valve seal 20 with the valve seat 13 is achieved as the valve disc 18 is pressed against the valve seat 13. Thus the closing cycle is completed.
According to the provisions of the patent statutes, the principle, construction and mode of operation of the present invention have been explained along with illustrations and a description of what is considered to be the best mode for carrying out that invention. However, it is to be understood that, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically illustrated and described.
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A pivotal disc shut-off valve is disclosed wherein a disc is pressed against a peripheral seat within a valve body to halt the flow of fluid material in a flow line. The disc is operated by a system of linkage arranged so as to allow the disc to be linearly moved in relation to the seat as a separate and distinct motion from pivotation of the disc. In closing the valve, a provision is made by which the disc is rocked as it contacts the seat to insure full closure. All motions of the disc are positively directed, with no reliance on the force of gravity, thus allowing the valve to be used in all positions.
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BACKGROUND
[0001] Buildings and other habitable environments create a barrier to weather and other elements. Many buildings are designed to keep out water in the form of rain, snow, and ice. Many buildings create an internal environment with a temperature that is different than the external environment. In a hot climate or season, a building may have air conditioning to provide a lower internal temperature than the outside temperature. Similarly, in a cold climate or season, a building may have internal heating to provide a warmer temperature inside than out.
[0002] When temperature differentials between internal and external environments exist, there is a possibility of condensation, high humidity, and other moisture related issues in building design. Further, many buildings may be designed with various mechanisms to allow air exchange between the internal and external environments.
SUMMARY
[0003] A barrier membrane for use in building construction may be manufactured by forming a polymeric film coating on release paper or film; or on nonwoven textiles, paper, fiberglass, or other structural substrate to improve tensile strength. Alternatively, the film may be fully or partially formed and then bonded to a structural substrate. A porous film coating or laminate may be formed using PVDF, PVC, and various polyolefins. A typical membrane may be less than 100 mil thick and greater than 50% porous, and may have a barrier to a passage of water in the liquid phase while retaining gas permeability. Some embodiments may contain active ingredients to combat bacterial or fungal growth, repel insects, or absorb environmental pathogens. The active ingredients may be applied after the porous film is manufactured or may be incorporated during the film manufacturing process.
[0004] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] In the drawings,
[0006] FIG. 1 is a diagram illustration of an embodiment showing a cross-section of reinforced porous material.
[0007] FIG. 2 is a flowchart illustration of an embodiment showing a method for forming a porous material.
[0008] FIG. 3 is a diagram illustration of an embodiment showing a process for continuous manufacturing of reinforced porous material.
[0009] FIG. 4 is a diagram illustration of an embodiment showing a process for a dip method of continuous manufacturing of reinforced porous material.
[0010] FIG. 5 is a diagram illustration of an embodiment showing a one-sided laminating method for manufacturing a reinforced porous film.
[0011] FIG. 6 is a diagram illustration of an embodiment showing a two-sided laminating method for manufacturing a reinforced porous film.
[0012] FIG. 7 is a flowchart illustration of an embodiment showing a method for forming a porous material with loading.
[0013] FIG. 8 is a diagram illustration of an embodiment showing a cross-section of batting insulation with a vapor barrier.
[0014] FIG. 9 is a diagram illustration of an embodiment showing a cross-section of an exterior wall from a top view.
[0015] FIG. 10 is a diagram illustration of an embodiment showing a cross-section of a second construction for an exterior wall from a top view.
[0016] FIG. 11 is a diagram illustration of an embodiment showing a cross-section of a roofing system.
[0017] FIG. 12 is a diagram illustration of an embodiment showing a cross-section of a crawlspace.
DETAILED DESCRIPTION
[0018] A reinforced porous film may be constructed through various processes and using various formulations to be used in different applications within the building and construction trades. The reinforced films may be used as a barrier film within an exterior wall, roof, or floor, as a vapor barrier for insulation, and for other uses. The reinforced films may also be used for interior applications, such as wallboard, wall paper, underneath plaster, underneath flooring materials, and other applications.
[0019] In some applications, the porous film may be loaded with various materials that may prevent or inhibit fungal or bacterial growth, repel insects, or otherwise prevent microbes or pests from passing through. Some applications may include materials that may absorb environmental pathogens. Such materials may be included in the porous film by including the materials during the formation of the porous material or after the porous material has been formed.
[0020] A reinforced porous film may be created by several methods. Porous films by nature may be structurally weak, especially films with high porosity. A reinforced film may be considerably more structurally sound than an unreinforced film. Increased mechanical properties may help during handling and manufacturing of the film into various products, as well as increased structural properties of an end product.
[0021] One method for producing a reinforced porous film may be to create the porous material with a reinforcement. For example, a solution used to create the porous material may be cast or sprayed onto the reinforcement. In another example, the reinforcement may be dipped into the solution.
[0022] Another method for producing a reinforced porous film may be to form a porous film and subsequently bond the porous film to a reinforcement. The bonding may be accomplished using mechanical interlocking, heat fusing, adhesives, or any other mechanism.
[0023] The reinforcement may be any type of woven or nonwoven material, perforated film, or any other web material. For the purposes of this specification, any references to any type of reinforcing web shall be interpreted to mean any type of reinforcing web, including nonwoven and woven reinforcement.
[0024] Specific embodiments of the subject matter are used to illustrate specific aspects. The embodiments are by way of example only, and are susceptible to various modifications and alternative forms. The appended claims are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.
[0025] Throughout this specification, like reference numbers signify the same elements throughout the description of the figures.
[0026] When elements are referred to as being “connected” or “coupled,” the elements can be directly connected or coupled together or one or more intervening elements may also be present. In contrast, when elements are referred to as being “directly connected” or “directly coupled,” there are no intervening elements present.
[0027] FIG. 1 is a schematic diagram of an embodiment 100 showing a cross section of porous material that may be formed using a solution of a polymer dissolved in a solvent and a miscible pore forming agent that has a higher surface energy. The porous material 102 and 104 is shown on both sides of a web 106 .
[0028] FIG. 1 is not to scale and is a schematic diagram. In some embodiments, the porous material 102 and 104 may impregnate the non-woven web 106 . Such embodiments may have partial impregnation or complete impregnation of porous material 102 and 104 into the thickness of the non-woven web 106 . Some embodiments may have mechanical or chemical adhesion of the porous material 102 and 104 to the surface of the non-woven web 106 . Other embodiments may vary in cross section based on the specific manufacturing process used and may have full impregnation or very little mechanical interlocking between the layers.
[0029] Embodiment 100 may be manufactured by several different methods. In some cases, the porous material 102 and 104 may be formed separately and bonded to the non-woven reinforcement 106 . In other cases, the porous material 102 and 104 may be formed from a solution that may be applied to the reinforcement 106 in a liquid form and processed to yield the porous material 102 and 104 with the reinforcement 106 .
[0030] FIG. 2 is a flowchart diagram of an embodiment 200 showing a method for forming a porous material. Embodiment 200 is a general method, examples of which are discussed below.
[0031] In block 202 , a solution may be formed with a polymer dissolved in a first liquid and a second liquid that may act as a pore forming agent. The liquids may be selected based on boiling points or volatility and surface tension so that when processed, the polymer is formed with a high porosity. Examples of such liquids are discussed below.
[0032] After forming the solution in block 202 , the solution is applied to a carrier in block 204 . The carrier may be any type of material. In some cases, a flat sheet of porous material may be cast onto a table top, which acts as a carrier in a batch process. In other cases, a film such as a polymer film, treated or untreated kraft paper, aluminum foil, or other backing or carrier material may be used in a continuous process. In such cases, a porous film may be manufactured and attached to a reinforcing web in a secondary process. In still other cases, the carrier material may be a nonwoven, woven, perforated, or other reinforcing web. In such cases, the solution may be applied by dipping, spraying, casting, extruding, pouring, spreading, or any other method of applying the solution.
[0033] The reinforcing web may be any type of reinforcement, including polymer based nonwoven webs, paper products, and fiberglass. In some cases, a woven material may be used with natural or manmade fibers, while in other cases, a solid film may be perforated and used as a reinforcing web.
[0034] In block 206 , enough of the primary liquid may be removed so that the dissolved polymer may begin to gel. In some embodiments, some, most, or substantially all of the primary liquid may be removed in block 206 . As the polymer begins to gel, the mechanical structure of the material may begin to take shape and the porosity may begin to form. During this time, the material may have some mechanical properties so that different mechanisms may be used to remove any remaining primary liquid and the secondary liquid.
[0035] The secondary liquid may be removed in block 208 . During the gelling process of block 206 , the differences in surface tension between the various materials may allow the secondary liquid to coalesce and form droplets, around which the polymer may gel as the first liquid is removed. After or as the polymer solidifies, the second liquid may be removed. In some cases, the boiling point or volatility of the two liquids may be selected so that the primary liquid evaporates prior to the secondary liquid.
[0036] The mechanisms for removing the primary and secondary liquids may be any type of suitable mechanism for removing a liquid. In many cases, the primary liquid may be removed by a unidirectional mass transfer mechanism such as evaporation, wicking, blotting, mechanical compression or others. Some methods may use bidirectional mass transfer such as rinsing or washing. In some cases, one method may be used to remove the primary liquid and a second method may be used for the secondary liquid. For example, the primary liquid may be at least partially removed by evaporation while the remaining primary liquid and secondary liquid may be removed by rinsing or mechanically squeezing the material.
[0037] Three embodiments are presented below of formulations and methods of production for porous material.
[0038] In a first embodiment, the porous material may be formed by first forming a layer of a polymer solution on a substrate, wherein the polymer solution may comprise two miscible liquids and a polymer material dissolved therein, wherein the two miscible liquids may comprise (i) a principal solvent liquid that may have a surface tension at least 5% lower than the surface energy of the polymer and (ii) a second liquid that may have a surface tension at least 5% greater than the surface energy of the polymer. Second, a gelled polymer may be produced from the layer of polymer solution under conditions sufficient to provide a non-wetting, high surface tension solution within the layer of polymer solution; and, thirdly, rapidly removing the liquid from the film of gelled polymer by unidirectional mass transfer without dissolving the gelled polymer to produce the strong, highly porous, microporous polymer 102 and 104 .
[0039] In a second embodiment, the porous material 104 may be produced using a method comprising:
[0040] (i) preparing a solution of one or more polymers in a mixture of a principal liquid which is a solvent for the polymer and a second liquid which is miscible with the principal liquid, wherein (i) the principal liquid may have a surface tension at least 5% lower than the surface energy of the polymer, (ii) the second liquid may have a surface tension at least 5% higher than the surface energy of the polymer, (iii) the normal boiling point of the principal liquid is less than 125° C. and the normal boiling point of the second liquid is less than about 160° C., (iv) the polymer may have a lower solubility in the second liquid than in the principal liquid, and (v) the solution may be prepared at a temperature less than about 20° C. above the normal boiling point of the principal liquid and while precluding any substantial evaporation of the principal liquid;
[0041] (ii) reducing the temperature of the solution by at least 5° C. to a temperature between the normal boiling point of the principal liquid and the temperature of the substrate upon the solution is to be cast;
[0042] (iii) casting the polymer solution onto a high surface energy substrate to form a liquid coating thereon, said substrate having a surface energy greater than the surface energy of the polymer; and
[0043] (iv) removing the principal liquid and the second liquid from the coating by unidirectional mass transfer without use of an extraction bath, (ii) without re-dissolving the polymer, and (iii) at a maximum air temperature of less than about 100° C. within a period of about 5 minutes, to form the strong, highly porous, thin, symmetric polymer membrane.
[0044] In a third embodiment, the porous material 104 may be produced by a method comprising:
[0045] (i) dissolving about 3 to 20% by weight of a polymer in a heated multiple liquid system comprising (a) a principal liquid which is a solvent for the polymer and (b) a second liquid to form a polymer solution, wherein (i) the principal liquid may have a surface tension at least 5% lower than the surface energy of the polymer, (ii) the second liquid may have a surface tension at least 5% greater than the surface energy of the polymer; and (iii) the polymer may have a lower solubility in the second liquid than it has in the principal solvent liquid;
[0046] (ii) reducing the temperature of the solution by at least 5° C. to between the normal boiling point of the principal liquid and the temperature of the substrate upon which it will be cast;
[0047] (iii) casting a film of the fully dissolved solution onto a substrate which may have a higher surface energy than the surface energy of the polymer;
[0048] (iv) precipitating the polymer to form a continuous gel phase while maintaining at least 70% of the total liquid content of the initial polymer solution, said precipitation caused by a means selected from the group consisting of cooling, extended dwell time, solvent evaporation, vibration, or ultrasonics; and
[0049] (v) removing the residual liquids without causing dissolution of the continuous gel phase by unidirectional mass transfer without any extraction bath, at a maximum film temperature which is less than the normal boiling point of the lowest boiling liquid, and within a period of about 5 minutes, to form a strong, highly porous, thin, symmetric polymer membrane.
[0050] The preceding embodiments are examples of different methods by which a porous material may be formed from a liquid solution to a porous polymer. Different embodiments may be used to create the porous material 102 and 104 and such embodiments may contain additional steps or fewer steps than the embodiments described above. Other embodiments may also use different processing times, concentrations of materials, or other variations.
[0051] Each of the embodiments of porous material 102 and 104 may begin with the formation of a solution of one or more soluble polymers in a liquid medium that comprises two or more dissimilar but miscible liquids. To form highly porous products, the total polymer concentration may generally be in the range of about 3 to 20% by weight. Lower polymer concentrations of about 3 to 10% may be preferred for the preparation of membranes having porosities greater than 70%, preferably greater than 75%, and most preferably greater than 80% by weight. Higher polymer concentrations of about 10 to 20% may be more useful to prepare slightly lower porosity membranes, i.e. about 60 to 70%.
[0052] A suitable temperature for forming the polymer solution may generally range from about 40° C. up to about 20° above the normal boiling point of the principal liquid, preferably about 40 to 80° C., more preferably about 50° C. to about 70° C. A suitable pressure for forming the polymer solution may generally range from about 0 to about 50 psig. In some embodiments, the polymer solution may be formed in a vacuum. Preferably a sealed pressurized system is used.
[0053] The material 102 may be formed in the presence of at least two dissimilar but miscible liquids to form the polymer solution from which a polymer film may be cast. The first “principal” liquid may be a better solvent for the polymer than the second liquid and may have a surface tension at least 5%, preferably at least 10%, lower than the surface energy of the polymer involved. The second liquid may be a solvent or a non-solvent for the polymer and may have a surface tension at least 5%, preferably at least 10%, greater than the surface energy of the polymer.
[0054] The principal liquid may be at least 70%, preferably about 80 to 95%, by weight of the total liquid medium. The principal liquid may dissolve the polymer at the temperature and pressure at which the solution may be formed. The dissolution may generally take place near or above the boiling temperature of the principal liquid, usually in a sealed container to prevent evaporation of the principal liquid. The principal liquid may have a greater solvent strength for the polymer than the second liquid. Also, the principal liquid may have a surface tension at least about 5%, preferably at least about 10%, lower than the surface energy of the polymer. The lower surface tension may lead to better polymer wetting and hence greater solubilizing power.
[0055] The second liquid, which may generally represent about 1 to 10% by weight of the total liquid medium, may be miscible with the first liquid. The second liquid may or may not dissolve the polymer as well as the first liquid at the selected temperature and pressure. The second liquid may have a higher surface tension than the surface energy of the polymer. Preferably, the second liquid may or may not wet the polymer at the gelation temperature though it may wet the polymer at more elevated temperatures.
[0056] Table A and Table B identify some specific principal and second liquids that may be used with typical polymers, especially including PVDF. PVDF may be used as a homopolymer or as a copolymer with hexofloropropolyne. Table A lists liquids that have at least some degree of solubility towards PVDF (surface energy of 35 dyne/cm), which may produce the dissolved polymer solution in the first step of the process. Ideally, a liquid may be selected from Table A that has solubility limits between 1% and 50% by weight of polymer at a temperature within the range of about 20 and 90° C. The liquids in Table B, on the other hand, may have lower polymer solubility than those in Table A, but may be selected because they have a higher surface tension than both the principal liquid and the polymers that may be dissolved in the solution made with liquid(s) from Table A.
[0057] Tables A and B represent typical examples of suitable liquids that may be used to create a porous material 102 and 104 . Other embodiments may use different liquids as a principal liquid or second liquid.
[0058] Examples of suitable liquids for use as the principal liquid, along with their boiling point and surface tensions are provided in Table A below. The table is arranged in order of increasing boiling point, which is a useful parameter for achieving rapid gelling and removal of the liquid during the film formation step. In some applications, a lower boiling point may be preferred.
[0000]
TABLE A
Normal Boiling
Surface Energy,
Principal Liquid
Point, EC
dynes/cm
methyl formate
31.7
24.4
acetone (2-propanone)
56
23.5
methyl acetate
56.9
24.7
Tetrahydrofuran
66
26.4
ethyl acetate
77
23.4
methyl ethyl ketone (2-butanone)
80
24
Acetonitrile
81
29
dimethyl carbonate
90
31.9
1,2-dioxane
100
32
Toluene
110
28.4
methyl isobutyl ketone
116
23.4
[0059] Examples of suitable liquids for use as the second liquid, along with their boiling point and surface tensions are provided in Table B below. This table is arranged in order of increasing surface tension as higher surface tension may result in optimum pore size distributions during the gelling and liquid removal steps of the process.
[0000]
TABLE B
Normal boiling
Surface Energy,
Second Liquid
point, ° C.
dynes/cm
nitromethane
101
37
bromobenzene
156
37
formic acid
100
38
pyridine
114
38
ethylene bromide
131
38
3-furaldehyde
144
40
bromine
59
42
tribromomethane
150
42
quinoline
24
43
nitric acid (69%)
86
43
water
100
72.5
[0060] The porous material may be formed by using a liquid medium for forming the polymer solution. The liquid medium may be rapidly removable at a sufficiently low temperature so that the second liquid may be removed without re-dissolving the polymer during the liquid removal process. The liquid medium may or may not be devoid of plasticizers. The liquids that form the liquid medium may be relatively low boiling point materials. In many embodiments, the liquids may boil at temperatures less than about 125° C., preferably about 100° C. and below. Somewhat higher boiling point liquids, i.e. up to about 160° C., may be used as the second liquid if at least about 60% of the total liquid medium is removable at low temperature, e.g. less than about 50° C. The balance of the liquid medium can be removed at a higher temperature and/or under reduced pressure. Suitable removal conditions depend upon the specific liquids, polymers, and concentrations utilized.
[0061] Preferably the liquid removal may be completed within a short period of time, e.g. less than 5 minutes, preferably within about 2 minutes, and most preferably within about 1.5 minutes. Rapid low temperature liquid removal, preferably using air flowing at a temperature of about 80° C. and below, most preferably at about 60° C. and below, without immersion of the membrane into another liquid has been found to produce a membrane with enhanced uniformity. The liquid removal may be done in a tunnel oven with an opportunity to remove and/or recover flammable, toxic or expensive liquids. The tunnel oven temperature may be operated at a temperature less than about 90° C., preferably less than about 60° C.
[0062] The polymer solution may become supersaturated in the process of film formation. Generally cooling of the solution will cause the supersaturation. Alternatively, the solution may become supersaturated after film formation by means of evaporation of a portion of the principal liquid. In each of these cases, a polymer gel may be formed while there is still sufficient liquid present to generate the desired high void content in the resulting polymer film when that remaining liquid is subsequently removed.
[0063] After the polymer solution has been prepared, it may then be formed into a thin film. The film-forming temperature may be preferably lower than the solution-forming temperature. The film-forming temperature may be sufficiently low that a polymer gel may rapidly form. That gel may then be stable throughout the liquid removal procedure. A lower film-forming temperature may be accomplished, for example, by pre-cooling the substrate onto which the solution is deposited, or by self-cooling of the polymer solution by controlled evaporation of a small amount of the principal liquid.
[0064] The film-forming step may occur at a lower temperature (and often at a lower pressure) than the solution-forming step. Commonly, it may occur at or about room temperature. However, it may occur at any temperature and pressure if the gelation of the polymer is caused by means other than cooling, such as by slight drying, extended dwell time, vibrations, or the like. Application as a thin film may allow the polymer to gel in a geometry defined by the interaction of the liquids of the solution.
[0065] The thin film may be formed by any suitable means. Extrusion or flow through a controlled orifice or by flow through a doctor blade may be commonly used. The substrate onto which the solution may be deposited may have a surface energy higher than the surface energy of the polymer. Examples of suitable substrate materials (with their surface energies) include copper (44 dynes/cm), aluminum (45 dynes/cm), glass (47 dynes/cm), polyethylene terephthalate (44.7 dynes/cm), and nylon (46 dynes/cm). In some cases a metal, metalized, or glass surface may be used. More preferably the metalized surface is an aluminized polyalkylene such as aluminized polyethylene and aluminized polypropylene.
[0066] In view of the thinness of the films, the temperature throughout may be relatively uniform, though the outer surface may be slightly cooler than the bottom layer. Thermal uniformity may enable the subsequent polymer precipitation to occur in a more uniform manner.
[0067] The films may be cooled or dried in a manner that prevents coiling of the polymer chains. Thus the cooling/drying may be conducted rapidly, i.e. within about 5 minutes, preferably within about 3 minutes, most preferably within about 2 minutes, because a rapid solidification of the spread polymer solution facilitates retention of the partially uncoiled orientation of the polymer molecules when first deposited from the polymer solution.
[0068] The process may entail producing a film of gelled polymer from the layer of polymer solution under conditions sufficient to provide a non-wetting, high surface tension solution within the layer of polymer solution. Preferably gelation of the polymer into a continuous gel phase occurs while maintaining at least 70% of the total liquid content of the initial polymer solution. More particularly, the precipitation of the gelled polymer is caused by a means selected from a group consisting of cooling, extended dwell time, solvent evaporation, vibration, or ultrasonics. Then, the balance of the liquids may be removed by a unidirectional process, usually by evaporation, from the formed film to form a strong micro-porous membrane of geometry controlled by the combination of the two liquids in the medium. In some embodiments, a liquid bath may be used to extract the liquids from the membrane. In other embodiments, the liquid materials may evaporate at moderate temperatures, i.e. at a temperature lower than that used for the polymer dissolution to prepare the polymer solution. The reduced temperature may be accomplished by the use of cool air or even the use of forced convection with cool to slightly warmed air to promote greater evaporative cooling.
[0069] The interaction among the two liquids (with their different surface tension characteristics) and the polymer (with a surface energy intermediate the surface tensions of the liquids) may yield a membrane with high porosity and relatively uniform pore size throughout its thickness. The surface tension forces may act at the interface between the liquids and the polymer to give uniformity to the cell structure during the removal step. The resulting product may be a solid polymeric membrane with relatively high porosity and uniformity of pore size. The strength of the membrane in some embodiments may be surprisingly high, due to the more linear orientation of polymer molecules.
[0070] The ratio of the principal liquid to the second liquid at the point of gelation may be adjusted such that the surface tension of the composite liquid phase may be greater than the surface energy of the polymer. The calculation of the composite liquid surface tension can be predicted based upon the mol fractions of liquids, as defined in “Surface Tension Prediction for Liquid Mixtures,” AlChE Journal, vol 44, no. 10, p. 2324, 1998, the subject matter of which is incorporated herein by reference.
[0071] Thermodynamic calculations show that adiabatic cooling of a solution can be significant initially and that the temperature gradient through such a film is very small. The latter may be considered responsible for the exceptional uniformity obtained using these methods.
[0072] The polymers used to produce the microporous membranes of the present invention may be organic polymers. Accordingly, the microporous polymers comprise carbon and a chemical group selected from hydrogen, halogen, oxygen, nitrogen, sulfur and a combination thereof. In a preferred embodiment, the composition of the microporous polymer may include a halogen. Preferably, the halogen is selected from the group consisting of chloride, fluoride, and a mixture thereof.
[0073] Suitable polymers for use herein may be include semi-crystalline or a blend of at least one amorphous polymer and at least one crystalline polymer.
[0074] Preferred semi-crystalline polymers may be selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polyvinylidene chloride, chlorinated polyvinyl chloride, polymethyl methacrylate, and mixtures of two or more of these semi-crystalline polymers.
[0075] In some embodiments, the products produced by the processes described herein may be used as a battery separator. For this use, the polymer may comprise a polymer selected from the group consisting of polyvinylidene fluoride (PVDF), polylvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinyl chloride, and mixtures thereof. Still more preferably the polymer may comprise at least about 75% polyvinylidene fluoride.
[0076] The “MacMullin” or “McMullin” Number measures resistance to ion flow is defined in U.S. Pat. No. 4,464,238, the subject matter of which is incorporated herein by reference. The MacMullin Number is “a measure of resistance to movement of ions. The product of MacMullin Number and thickness defines an equivalent path length for ionic transport through the separator. The MacMullin Number appears explicitly in the one-dimensional dilute solution flux equations which govern the movement of ionic species within the separator; it is of practical utility because of the ease with which it is determined experimentally.” The lower a MacMullin Number the better for battery separators, the better. Products using these techniques may have a low MacMullin number, i.e. about 1.05 to 3, preferably about 1.05 to less than 2, most preferably about 1.05 to about 1.8.
[0077] Good tortuosity is an additional attribute of some embodiments. A devious or tortuous flow path with multiple interruptions and fine pores may act as a filter against penetration of invading solids. Tortuosity of the flow path can be helpful to prevent penetration by loose particles from an electrode or to minimize growth of dendrites through a separator that might cause electrical shorts. This characteristic cannot be quantified, except by long-term use, but it can be observed qualitatively by viewing a cross-section of the porosity.
[0078] Some embodiments may be generally uniform and symmetric, i.e. the substrate side pores may be substantially similar in size to the central and the air side pores. Pores varying in diameter by a factor of about 5 or less may be sufficiently uniform for the membranes to function in a symmetric manner.
[0079] Where additional strength or stiffness may be needed for handling purposes, micro- or nano-particles can be added to the formulation with such particulates residing within the polymer phase. A few such additives include silica aerogel, talc, and clay.
[0080] FIG. 3 is a diagram illustration of an embodiment 300 showing a process for continuous manufacturing of reinforced porous material. Embodiment 300 is an example of a general process that may be used to form porous material directly in a reinforced web, such as a nonwoven web, woven web, or perforated film.
[0081] A web 302 may be unwound with an unwinding mechanism 304 and moved in the direction of travel 301 . Various reinforcement webs may be used, including woven and nonwoven. In many embodiments, a nonwoven web may be preferred from a cost standpoint.
[0082] As the web 302 is being moved in the direction 301 , solution 302 may be applied to the web 302 with an applicator 308 . The applicator 308 may apply a wet solution 306 to form an uncured solution 310 .
[0083] In some embodiments, a carrier material may be used to facilitate handling of the web and may provide a bottom surface against which the liquid solution 306 may be supported while in the uncured state. Such carrier material may include treated kraft paper, various polymeric films, metal films, metalized carriers, or other material. Some embodiments may use a carrier material in subsequent manufacturing steps and may include the carrier material with the cured porous material 314 on the take up mechanism 316 . In other embodiments, the carrier material may be stripped from the cured porous material 314 before the take up mechanism 316 . In still other embodiments, a continuous recirculating belt or screen may be used beneath the web 302 during processing.
[0084] The embodiment 300 illustrates a manufacturing sequence that may be predominantly horizontal. In other embodiments, a vertical manufacturing process may have a direction of travel in either vertical direction, either up or down. A vertical direction of travel may enable a porous material to evenly form on two sides of a reinforcement web. Such an embodiment may have an applicator system that may apply solution to both sides of a reinforcement web. Horizontal manufacturing processes, such as embodiment 300 , may result in a final product that may be asymmetrical, with the reinforcement web being located off the centerline of the thickness of the material.
[0085] The applicator 308 may be any mechanism by which the solution 306 may be applied to the web 302 . In some embodiments, the solution 306 may be continuously cast, sprayed, extruded, or otherwise applied. Some embodiments may use a doctor blade or other mechanism to distribute the solution 306 .
[0086] The thickness of the resulting reinforced porous material may be adjusted by controlling the amount of solution 306 that is applied to the web 302 and the speed of the web during application, among other variables.
[0087] Some embodiments may includes various additional processes, such as air knives, calendering, rolling, or other processing before, during, or after the solution 306 has formed into a solid porous polymer material.
[0088] The uncured solution 310 may be transferred through a tunnel oven 312 or other processes in order to form a cured porous material 314 , which may be taken up with a take up mechanism 316 .
[0089] The tunnel oven 312 may have different zones for applying various temperature profiles to the uncured solution 310 in order to form a porous material. In many cases, an initial lower temperature may be used to evaporate a portion of a primary liquid and begin formation of a solid polymer structure. A higher temperature may be used to remove a second liquid and remaining primary liquid.
[0090] In some embodiments, the tunnel oven 312 may provide air transfer using heated or cooled air to facilitate curing.
[0091] Embodiment 300 is an example of a continuous process for manufacturing a reinforced porous material by forming the porous material by introducing a wet solution directly onto the reinforcement media. Other embodiments may include casting a porous material directly onto a reinforced web in a batch mode, such as casting on non-moving table surface.
[0092] FIG. 4 is a diagram illustration of an embodiment 400 showing a dip method for continuous manufacturing of reinforced porous material.
[0093] A web 402 is unwound from an unwinding mechanism 404 and passed through a solution 406 in a bath 408 to form a web with uncured solution 410 . The bath 408 may be ultrasonically activated to remove air and promote wetting of the reinforcement by the solution. The web may pass through a curing zone 412 in which may remove a primary and secondary liquid while forming a polymer with a porous structure. The cured material on a web 414 may be taken up in a take up reel 416 .
[0094] Embodiment 400 is an example of a continuous process for forming a porous material directly onto a reinforcement web. By controlling the viscosity of the solution 406 and the speed of operation, a controlled thickness of porous material may be formed. In some embodiments, a doctor blade, calendering mechanism, air knives, or other mechanisms may be used to provide additional control over the thickness of the uncured or cured material.
[0095] The curing zone 412 may be any type of mechanism by which the uncured material 410 may be cured. Some embodiments may process the material through various heated or cooled zones, apply various rinses, process the material through a pressurized or vacuum environment, or provide some mechanical processing such as calendering, squeezing, or some other process. Each embodiment may have particular processing performed based on the selection of polymer, the formulation of the solution 406 , and the construction of the reinforcing web 402 .
[0096] In some embodiments, the reinforcing web 402 may have various treatments applied prior to coming in contact with the solution 406 . For example, a sizing or other liquid material may be applied to the web 402 . One example may be to pretreat the web 402 with a dilute version of the solution 406 or a solution with a different solvent/polymer combination. In some cases, such a pretreatment may cause the reinforcing web 402 to swell or otherwise improve the bonding of the porous material to the web 402 . Other examples may include applying a corona or spray to the web 402 to partially oxidize the surface of the web 402 . Another example may be to apply an electric charge to the web 402 and an opposite charge to the bath 408 . Still another example may be to ionize the surface of the reinforcing web 402 . Such pretreatment processes may be used with any method for manufacturing a reinforced porous film.
[0097] Ultrasonic activation of the solution 406 and reinforcing web 402 may enhance bonding and penetration of the solution 406 into the web.
[0098] Ultrasonic activation may be used to supplement any type of mechanism by which a pore forming polymer solution may be applied to a reinforcing web. In some embodiments, ultrasonic energy may be introduced to the solution, while in other embodiments, ultrasonic energy may be applied to the reinforcing web before or after the solution is applied. In embodiment 400 , ultrasonic energy may be applied to the bath 408 or to the reinforcing web 402 prior to entering the bath 408 . Some embodiments may introduce ultrasonic energy to the web after the solution is applied by using an ultrasonic horn directed toward the web.
[0099] FIG. 5 is a diagram illustration of an embodiment 500 showing a method for laminating reinforced porous film. Embodiment 500 shows a single cured porous film 502 being joined to one side of a reinforced web 506 .
[0100] The porous film 502 may be unwound from an unwinding mechanism 504 and brought into contact with a reinforcement web 506 that is unwound from a second unwinding mechanism 508 . The two plies may be joined by the rollers 510 to form a reinforced porous film 512 that may be wound onto a take up reel 514 .
[0101] Embodiment 500 is a method and apparatus for laminating a porous film 504 with a reinforcement web 506 . In some embodiments, an applicator 516 may be used to deliver ionic charge, adhesive, heat, or any other material or processing at the nip point of the joining process.
[0102] An adhesive may be used to join the two layers. In some embodiments, the adhesive may contain a solvent that may enable a portion of either or both the polymer from the porous material or the reinforcement web to melt or dissolve and fuse with the other layer. In some cases, a polymer mixture may be used in forming the porous material with one of the polymers in the mixture selected to dissolve in an adhesive to facilitate the bonding to the reinforcement web. Another type of adhesive may contain a dissolved polymer that gels between the two layers to join the layers together. Another adhesive may be heat activated and may partially melt to join the layers.
[0103] When adhesives are used, some embodiments may apply a coating of adhesive across one or both of the surfaces to be joined. Other embodiments may apply spots of adhesive in various locations or patterns.
[0104] The applicator 516 may apply heat to one or more surfaces to be joined. In some embodiments, the heat may enable a portion of one or more of the materials to be joined to melt and fuse with the other. Such heat may be applied in conjunction with an adhesive.
[0105] In some embodiments, the porous film 502 and reinforcement web 506 may be joined together by mechanical interlocking. Such interlocking may be created by applying pressure between the rollers 510 .
[0106] In some cases, the porous film 502 may be transferred through a portion of the manufacturing process using a carrier film or other material. In such a case, the carrier film may be removed prior to entering the rollers 510 .
[0107] FIG. 6 is a diagram illustration of an embodiment 600 showing a laminating method for two-sided lamination of porous film onto a central reinforced web. Embodiment 600 may use similar processing to that of embodiment 500 , with the addition of a second layer of porous film added so that the reinforcing web is in the center of the laminate.
[0108] A first porous film 602 may be unwound from an unwinding mechanism 604 , and similarly a second porous film 606 may be unwound from unwinding mechanism 608 . A reinforcement web 610 is unwound from an unwinding mechanism 612 and laminated between the porous film layers 602 and 606 at the rollers 612 to form a laminate 614 that is taken up by a take up reel 616 .
[0109] Embodiment 600 may join the layers of porous film and a reinforcement web by any mechanism whatsoever. In some cases, mechanical interlocking may be used, while in other cases, applicators 620 may apply heat and/or adhesives or other bonding agent or processing that may facilitate bonding.
[0110] An adhesive may be used to join the various layers. In some embodiments, the adhesive may contain a solvent that may enable a portion of either or both the polymer from the porous material or the reinforcement web to melt or dissolve and fuse with the other layer. In some cases, a polymer mixture may be used in forming the porous material with one of the polymers in the mixture selected to dissolve in an adhesive to facilitate the bonding to the reinforcement web. Another type of adhesive may contain a dissolved polymer that gels between the two layers to join the layers together. Another adhesive may be heat activated and may partially melt to join the layers.
[0111] When adhesives are used, some embodiments may apply a coating of adhesive across one or both of the surfaces to be joined. Other embodiments may apply spots of adhesive in various locations or patterns.
[0112] The applicator 620 may apply heat to one or more surfaces to be joined. In some embodiments, the heat may enable a portion of one or more of the materials to be joined to melt and fuse with the other. Such heat may be applied in conjunction with an adhesive.
[0113] FIG. 7 is a flowchart illustration of an embodiment 700 showing a method for creating a loaded porous material. The loading may be any nonstructural material that may perform various functions.
[0114] In some cases, a loading may be passive and perform a function without changing state or engaging in a chemical reaction. In other cases, an active loading may undergo a chemical reaction or otherwise change state.
[0115] Loading may be applied using two different application mechanisms. In one mechanism, a loading may be incorporated into the porous material solution and may become bound into the structure of the porous material. In another mechanism, a loading may be applied to the porous material after formation and may be captured within the pores of the porous material.
[0116] In some embodiments, a two part loading material may be used. In such an embodiment, a first material may be incorporated into the solution and may be captured within the porous structure. A second part of the loading material may be applied to the formed porous material and the second part may interact with the first part to create the loading. In some cases, the second part may react with the first part or otherwise cause the first part to undergo a chemical transformation.
[0117] The illustration of FIG. 7 is a similar process as FIG. 2 , with the addition of loading material prior to and/or after porous material formation.
[0118] The solution is formed in block 202 as described above.
[0119] Loading material may be added to the solution in block 702 . The loading material may be dissolved in the solution of block 202 or may be a particulate that may be suspended in the solution.
[0120] The solution may be applied to a carrier in block 204 , and enough of the primary solution may be removed in block 206 to begin gelation. The secondary liquid may be removed in block 208 .
[0121] Loading material may be added in block 704 which may be after the porous material is formed. In such a case, the loading material may be infused within the porous structure in several manners. In some cases, the loading material may be dissolved in a solution which may permeate the porous material. The solution may be dried, leaving a residue of loading material.
[0122] In some cases, a particulate loading material may be infused into the porous structure as a dry material or with a liquid carrier.
[0123] In some embodiments, other mechanisms for depositing a loading material may include vacuum deposition mechanisms, surface treatments, or other mechanisms. In some embodiments, the loading material may be applied through the porous structure, while in other cases, the loading material may be applied to the outer surface of the porous structure.
[0124] The reinforced porous material may be used in various construction applications. For example, the porous material may be used as a barrier in an exterior wall, roof, or floor. The barrier may be applied underneath siding, stucco, or roofing materials and be used as an air permeable yet watertight barrier. In some cases, insect repellant or anti-microbial loadings may be applied to the barrier to prevent infestation from insects or various microbes.
[0125] In some cases, the porous material may be applied between a building and foundation such as underneath a concrete slab, in a crawlspace, or other applications.
[0126] The porous material may be used as a vapor barrier in various insulating mechanisms. For example, the porous material may be used as a vapor barrier in fiberglass or other insulation batting. In some cases, the porous material may be applied in conjunction with sprayed or other in situ formed insulating systems.
[0127] Reinforced porous material may be used in many interior applications. For example, reinforced porous material may be used as a facing material for wallboard, both for common interior walls and for high humidity applications such as bathrooms and kitchens.
[0128] Underlayment applications for the porous material may include underlayment for flooring systems, including carpet and hardwood floors, and may be applied above or below various decking systems in different applications.
[0129] In some embodiments, the reinforced porous material may be used as wallpaper, a carrier for wallpaper, or may be applied to a wall prior to applying wallpaper.
[0130] FIG. 8 is a diagram illustration of an embodiment 800 showing a cross-section of insulation batting with a vapor barrier. Embodiment 800 is a simplified diagram that may illustrate the basic components of the embodiment. FIG. 8 is not to scale.
[0131] Embodiment 800 is a cross sectional illustration of an insulation batting material. A bat of fiberglass insulation 802 is joined to a laminate of a porous film vapor barrier 806 and kraft paper 804 . Embodiment 800 may be used like a conventional batting insulation material with a vapor barrier. Many embodiments are sized to fit between studs in walls of stick framed buildings or between joists in ceilings or floors.
[0132] Some embodiments may use different types of insulating material, such as rock wool or other bat-type insulation materials. In many cases, the batting insulation material may be flexible, while in some cases, the insulation material may be rigid.
[0133] The porous film vapor barrier 806 may be a microporous material as described above manufactured with a polymer, such as PVDF. The porous film vapor barrier 806 may or may not be created as a laminate with the kraft paper 804 . In some embodiments, the porous film vapor barrier 806 may have a woven or non-woven reinforcement.
[0134] The porous film vapor barrier 806 is illustrated as being between the kraft paper 804 and the insulating batting 802 . In other embodiments, the kraft paper 804 may be between the porous film vapor barrier 806 and the insulation batting 802 .
[0135] The insulation batting 802 may be adhered to the porous film vapor barrier 806 by adhesive.
[0136] Embodiment 800 is an example of a vapor barrier that may allow air exchange through the surface of the vapor barrier, but may prohibit water vapor transmission.
[0137] In some embodiments of a bat insulation system, a reinforced microporous polymer membrane may be used instead of a laminate of kraft paper 804 and porous film vapor barrier 806 .
[0138] In some embodiments, the porous film vapor barrier 806 may be impregnated with various materials. For example, the porous film vapor barrier 806 may be treated with an anti-microbial material, an anti-fungal material, an insecticide, or some other material to prevent unwanted mold, fungus, or insects to penetrate a building.
[0139] FIG. 9 is a diagram illustration of an embodiment 900 showing an exterior wall cross section. The illustration of FIG. 9 may be a top view of a horizontal cross section through a typical stick-framed residential or commercial building. FIG. 9 is not to scale.
[0140] Embodiment 900 is an example of a wall cross section that may be constructed with a vapor barrier that is placed on the exterior side of an insulating barrier. Such a construction may be useful in hot, humid climates where the interior of a building may be colder than the exterior. In such cases, a building may have air conditioning or other refrigeration.
[0141] Embodiment 900 shows an exterior surface 902 at the top of the illustration and an interior surface 910 at the bottom. Studs 908 and 910 are illustrated in cross section.
[0142] In a typical stick-framed residential contruction, the studs 908 and 910 may be constructed with exterior sheathing 912 and raised into position. After positioning the wall, insulation 918 may be applied and the interior surface may be finished with drywall 906 or some other interior surface treatment such as plaster and lath or other construction.
[0143] In some embodiments, the exterior walls of a building may be assembled and installed prior to applying a porous film vapor barrier 914 . After the porous film vapor barrier 914 is applied, an external siding system 916 may be applied over the porous film vapor barrier 914 .
[0144] FIG. 10 is a diagram illustration of an embodiment 1000 showing an exterior wall cross section. The illustration of FIG. 10 may be a top view of a horizontal cross section through a typical stick-framed residential or commercial building. FIG. 10 is not to scale.
[0145] Embodiment 1000 is an example of a wall cross section that may be constructed with a vapor barrier that is placed on the interior side of an insulating barrier. Such a construction may be useful in cold climates where the interior of a building may be predominately warmer than the exterior.
[0146] Embodiment 1000 is similar to embodiment 900 with the exception that the porous film vapor barrier 1012 is located on the interior side of the insulation 1018 . In embodiment 900 , the porous film vapor barrier 914 was located on the exterior side of the insulation 918 .
[0147] Embodiment 1000 illustrates an interior surface 1002 at the bottom of the illustration and an exterior surface 1004 at the top. Along the interior surface 1002 may be drywall 1006 or some other interior finish.
[0148] The porous film vapor barrier 1012 may be located external to the drywall 1006 , but on the interior side of the insulation 1018 . The studs 1008 and 1010 may be the vertical structural support of a wall, and may serve to separate the exterior surface and interior surface in order to place insulation 1018 .
[0149] On the exterior surface of the studs 1008 and 1010 is exterior sheathing 1014 and an exterior siding system 1016 .
[0150] In either embodiment 900 or 1000 , the insulation 1018 may be any type of insulation, such as fiber glass bat, rock wool, blown in fibrous insulation, form in place insulation, or any other insulation system.
[0151] In either embodiment 900 or 1000 , the interior finish material may be drywall as illustrated or some other interior finish system. Examples of other interior finish system may include paneling, plaster, tile, wallboard, tile, or any interior finish.
[0152] In either embodiment 900 or 1000 , the exterior siding system may be any type of exterior siding. Examples include lap siding, aluminum or vinyl siding, shake or shingle siding, brick siding, tile siding, stucco, plaster, or another type of exterior siding.
[0153] The construction of embodiments 900 and 1000 are illustrated as side walls of a typical framed residence. Other similar embodiments may be employed for roofing applications that may be flat or pitched roofing systems. In many pitched roofing systems, an airflow space may be provided between the insulation and exterior sheathing.
[0154] Embodiments 900 and 1000 illustrate an exterior wall of a building. The same or similar construction may be used for any exterior barrier, which may include walls, floors, or roofs. The construction may be made up of several layers that may be assembled or installed in different sequences to achieve the construction as shown. In some embodiments, additional materials or layers may be included in the assembly.
[0155] FIG. 11 is a diagram illustration of an embodiment 1100 showing a roofing system cross section. Embodiment 1100 may be a simplified example of a membrane style flat roofing system. FIG. 11 is not to scale.
[0156] Embodiment 1100 illustrates the interior surface 1102 on the bottom of the illustration and an exterior surface 1104 on the top. A joist 1106 is illustrated as running parallel to the illustration and supporting a decking system 1108 .
[0157] Above the decking system 1108 , a porous film vapor barrier 1110 may be installed.
[0158] Insulation 1112 may be installed over the porous film vapor barrier 1110 and a roofing membrane 1114 may be installed over the insulation 1112 .
[0159] FIG. 12 is a diagram illustration of an embodiment 1200 showing a cross section of a crawlspace. Embodiment 1200 is a simplified example of a typical construction that includes a crawlspace below the lowest floor of a building. In many embodiments, a crawlspace may be unheated.
[0160] Embodiment 1200 illustrates an exterior wall 1202 and a foundation 1204 that may rest on a footer 1206 . The foundation 1204 and footer 1206 may be buried in earth 1208 on the outside of the building and earth 1210 underneath the building.
[0161] The crawlspace 1212 may be a space above the earth 1210 and joists 1214 that support a floor.
[0162] A porous film vapor barrier 1218 may be placed above the joists 1214 and below a flooring system 1216 . The porous film vapor barrier 1218 may prevent vapor from infiltrating the interior of the building from the exposed earth 1210 in the crawlspace 1212 .
[0163] An alternative placement for a porous film vapor barrier 1220 may be below the lower surface of the joists 1214 .
[0164] In the embodiments 800 , 900 , 1000 , 1100 , and 1200 , the porous film vapor barrier may be infiltrated or coated with various anti-microbial agents that may inhibit mold, mildew, bacteria, or other unwanted organisms into a building. In some embodiments, the porous film vapor barrier may be infiltrated or coated with an insecticide or other agent that may kill or deter insects or other pests from entering a building. Such materials may be added to the porous film by dipping or spraying the film after manufacturing the film. In some embodiments, the materials may be added to the porous film by incorporating the materials in the solution prior to forming the porous film.
[0165] In embodiments with anti-pathogen properties such as anti-microbial properties described above, additives such as iodine, silver, silver oxide, silver nitrate, zinc, zinc sterate, copper glutamate, copper chloride, or other materials may be added to the microporous film. Such materials may be added to the polymer solution prior to forming the microporous film or by applying the materials after formation. Another material that may be added during formation may be an ultraviolet barrier may be created by adding zinc oxide to the microporous film.
[0166] In the embodiments 800 , 900 , 1000 , 1100 , and 1200 , the porous film vapor barrier may be constructed with any type of reinforcement material.
[0167] The foregoing description of the subject matter has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the subject matter to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments except insofar as limited by the prior art.
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A barrier membrane for use in building construction may be manufactured by forming a polymeric film coating on release paper or film; or on nonwoven textiles, paper, fiberglass, or other structural substrate to improve tensile strength. Alternatively, the film may be fully or partially formed and then bonded to a structural substrate. A porous film coating or laminate may be formed using PVDF, PVC, and various polyolefins. A typical membrane may be less than 100 mil thick and greater than 50% porous, and may have a hydrostatic head while retaining gas permeability. Some embodiments may contain active ingredients to combat bacterial or fungal growth, repel insects, or absorb environmental pathogens. The active ingredients may be applied after the porous film is manufactured or may be incorporated during the film manufacturing process.
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CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of copending application Ser. No. 310,274, filed Oct. 9, 1981, now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to pressure translators, in general, and to a pressure translator for use in converting a process pressure into a pneumatic measurement signal, in particular.
2. Background of the Prior Art
Pressure translators find application in such areas as pressure measurement, density measurement, fluid level measurement, and other areas where it is desirable to measure volume, flow or weight of fluids. In making such measurements, it is desirable not to interfere with the structure or system in which the fluid to be measured is being kept. In avoiding such interference, the process itself is protected.
Among the known measurement devices are those employing radiation, bubbling or sonic techniques. All of these devices add to or disturb the process fluid being measured. For certain fluids, radiation contamination and fluid component damage are real problems.
Thus, there is a need for a pressure translator for converting process pressure into a pneumatic signal which can be transmitted and measured by a pressure measurement device at a remote location. The present invention is directed toward filling that need.
SUMMARY OF THE INVENTION
The present invention relates to a pressure translator for converting a process pressure into a pneumatic signal which can be transmitted and measured by a pressure measurement device at a remote location. The pressure translator provides isolation for the process and the measuring equipment but still translates the process pressure with very high accuracy. The pressure translator employs a balanced valve in cooperation with a forced balanced diaphragm in order to accomplish the pressure translation.
The pressure translator basically comprises a hollow body portion within which is disposed a translator plate that divides the body cavity into an input chamber and an output chamber. The translator plate has one or more bores defined within the plate and extending from one surface of the plate to the other. A diaphragm is associated with and completely covers each of the translator plate surfaces, which are configured in such a way that each surface, together with the planar diaphragm, forms a volume of generally frustoconical shape with the diaphragm acting as the base. The frustoconical volumes together with the series of bores define a fluid reservoir. The diaphragm contained in the input chamber is referred to as an input diaphragm, whereas the diaphragm contained in the output chamber is referred to as an output diaphragm.
The input chamber has provisions for receiving fluid from a process vessel. In turn, the output chamber has provisions for receiving an output, signal tube and a valve assembly. The valve assembly in turn contains an input to which is secured one end of an air supply line. In this way, it is possible to inject air or testing fluid through a fixed orifice or restrictor into the output chamber by way of the valve assembly.
The valve assembly is constructed to have three valve chambers disposed in line. A valve seat is defined between each two adjacent chambers. Defined within the centrally positioned valve chamber is a vent port which permits the chamber to communicate with atmosphere. A fluid conduit is defined in the valve assembly so that the air supply may be directed to each of the valve chambers located on either side of the central valve chamber. The air supply is also in fluid communication with the output chamber. Movably mounted within the three valve chambers is a valve stem to which is secured a pair of valve heads, one associated with each of the valve seats. In a preferred embodiment each of the valve heads is in the shape of a ball.
To operate the pressure translator, a process pressure is applied to the input chamber and an air pressure under constant flow, as regulated by the fixed orifice, is introduced into the output chamber via the valve assembly. Under these conditions, the input diaphragm is forced toward the translator plate, causing the fluid in the fluid reservoir to move to the other side of the translator plate. This causes the output diaphragm and an attached operator disc to move away from the translator plate. Since the valve stem is connected directly to the operator disc, the valve stem assembly moves to close both valves. Closing the valves causes pressure in the output chamber to increase. When the output chamber pressure is equal to the process pressure, the movement of the fluid within the fluid reservoir stops and the valves vent the proper air to maintain a pressure in the output chamber equal to the process pressure. When the pressure is decreased in the input chamber, the reverse action takes place, thereby reducing the pressure in the output chamber to equal the input process pressure, thus giving rise to a pressure signal.
The pressure signal is transmitted via the output of the output chamber to a remote measurement device. The measurement device is of the type that does not require flow of air in order to produce a reading. The pressure translator is used as part of a closed system and no air movement other than the movement of the sensing element in the transducer or the gauge of the measurement instrument takes place. Under these conditions, the pressure on one end of the pneumatic line at the measurement instrument will be exactly equal to the pressure in the output chamber.
Thus, it is a primary object of the present invention to provide an improved pressure translator.
It is another object of the present invention to provide a pressure translator for use in converting a process pressure into a pneumatic measurement signal.
It is a further object of the present invention to provide a balanced valve for use in a pressure translator.
It is still an object of the present invention to provide a forced balanced diaphragm for use in a pressure translator.
It is yet an object of the present invention to provide a pressure translator using a balanced valve coupled with a forced balanced diaphragm.
It is still a further object of the present invention to provide a pressure translator that gives highly accurate readings of process pressure through the use of noninvasive techniques.
These and other objects will become apparent when considered in connection with the following drawings and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a pressure translator embodying the teachings of the present invention with a portion cut-away to reveal the interior structure of the translator.
FIG. 2 is a view taken along lines 2--2 of FIG. 1.
FIGS. 3a, 3b and 3c are views of the valve assembly as illustrated in FIG. 2 and are used to explain the operation of the assembly.
FIG. 4 is a block diagram of a measuring system employing the pressure translator of the present invention.
FIGS. 5a and 5b are views of the valve assembly of FIG. 2 with alternative valve seats and heads.
FIG. 6 is a view of the valve assembly of FIG. 2 with an alternative diaphragm connection assembly.
FIG. 7 is a fragmentary cross-sectional view of another embodiment of a valve assembly for a pressure translator in accordance with the present invention.
FIG. 8 is a fragmentary cross-sectional view of a further embodiment of a pressure translator in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
As best seen in FIGS. 1 and 2, the pressure translator, generally designated as 10, basically comprises a generally disc-shaped translator plate 12 interposed between a pair of upper and lower discs 14 and 16. As oriented in FIG. 1, lower disc 16, which is made from metal or a high strength plastic, has a planar outer surface 13 defined on one side of the disc. The opposite side of the disc 16 contains a first concentric bore 15 of desired depth to define an evacuated volume 20. A depressed, polished lip 17 is formed about the periphery of the bore 15 to provide a ledge for the polished rim defined by the surface 26 of the translator plate 12. In like manner, upper disc 14, which is also made from metal or high strength plastic, has a planar outer surface 19 defined on one side of the disc. The opposite side of the disc 14 also contains a concentric bore 21 of desired depth to define an evacuated volume 18. As with disc 16, disc 14 has a depressed, polished lip 23 formed about the periphery of bore 21 to provide a ledge for the polished rim defined by the surface 25 of the translator plate 12.
The upper surface 25 of the translator plate is generally concave as is the bottom surface 26 of the translator plate 12. As with the discs 14 and 16, the translator is made from metal or a high strength plastic. In a preferred embodiment, the configuration of surface 25 is made up of two surfaces: a concentric planar surface 25A essentially parallel to and spaced from the plane defined by the upper rim 27 of the translator plate 12; and a ring 25B that tapers outwardly from the peripheral edge of surface 25A to the interior portion of the rim 27. The same may be said for surface 26 where 26A represents the concentric planar surface, 26B the ring and 29 denotes the rim.
One or more bores 28 provide fluid communication between the upper and bottom surfaces 25 and 26. The bores are typically 0.016 to 0.125 inches in diameter and may be arranged in any pattern, so long as the holes are located under the area covered by discs 42 and 44, the details of which are described hereinafter. An output diaphragm 30 made of a thin film, such as a strong plastic film (Mylar) or a thin metal foil (stainless steel or brass), completely covers the top surface 25 and is positioned about the perimeter 32 of the translator plate 12 so as to define the space generally designated as 34. As can be seen, space 34 is in the form of a frustoconical section with the planar diaphragm 30 providing the base. An input diaphragm 36 of similar structure to that of the output diaphragm is similarly positioned relative to the bottom surface 26 to define another frustoconical space 38. The diaphragms 30 and 36, which are typically of 0.002 inch thick Teflon, are sealed on their edges by the pressure created at the upper and lower rims 27 and 29 of the translator plate. This pressure is developed when the upper and lower discs 14 and 16 with the translator plate 12 and diaphragms 30 and 36 interposed therebetween are all held together by a series of fasteners, such as bolts 51 and nuts 53, disposed about the periphery of the translator 10. In a preferred embodiment, there are six such fasteners disposed about the periphery of the translator 10. The number of fasteners is determined by the pressure being measured. The greater the pressure the greater the number of bolts.
Preferably, the diaphragms 30, 36 are not stretched, but are permitted to lie flat as they are sealed on their edges at the upper and lower rims 27, 29 of the translator plate. The sealing arrangement is enhanced by ensuring that the rims are polished and the depressed lips 17 and 23 are likewise polished.
The entire interior volume defined by the spaces 34 and 38 as well as the series of bores 28 define a fluid reservoir that is filled with a non-compressible viscous fluid, such as silicone liquid, oil or water.
Secured to the surface 40 of the film 36 is a generally planar metallic drive disc 42. In like manner, a generally planar metallic output disc 44 is secured to the surface 46 of the film 30 associated with the second chamber 24. In a preferred embodiment the discs 42 and 44 are secured to their respective films 36 and 30 by conventional means such as vulcanizing or gluing with a contact cement.
The lower body portion 16 has defined therein a through bore 48 extending from atmosphere to the interior of chamber 22. The bore 48, which is typically located concentric relative to the periphery 33 of the disc, is threaded to receive one end of an input tube 50 whose other end is connected to a process vessel (110 in FIG. 4) so as to provide fluid communication between the fluid within the process vessel and the input chamber 22.
Defined at the center of the upper body portion 14 is a bore 50 threaded to receive a valve assembly 60. Also defined in the upper body portion 14 is a through bore 52 extending from atmosphere to the interior of output chamber 24. The bore 52, which is typically located parallel to and spaced from the cylindrical axis of the disc 14, is threaded to receive a conventional coupling 35 associated with a tube 54, the other end of which is connected to a pressure measurement device (120 in FIG. 4) at a remote location. Through the connection with tube 54, fluid communication between the output chamber 24 and the remote measuring device is provided.
The valve assembly 60 basically comprises a valve body 62 within which is defined an elongated valve cavity 64. In a preferred embodiment, the valve body is generally cylindrically shaped. The valve cavity defines first, second and third chambers denoted 65,66 and 67, respectively. The three chambers are arranged in line with chamber 66 being intermediate chambers 65 and 67. Within the elongated cavity, the valve body 62 defines a chamfered valve seat 70 between chambers 65 and 66 and a valve seat 72 between chambers 66 and 67. Typically the chamfer is from 30° to 45° from the longitudinal axis of the valve cavity 64. Defined within chamber 66 is a vent port 74 which permits chamber 66 to communicate with atmosphere.
Defined within the valve body 62 is a first fluid passageway 76 that originates at chamber 65. In like manner, a second fluid passageway 78, which originates from chamber 67, is defined within the valve body 62. The free ends of both fluid passageways 76 and 78 meet at a common junction 80 and are joined in fluid communication with a third conduit 82 that terminates at the exterior of the valve body in a threaded portion 84 for receiving a conventional coupling 37 associated with a hose 86, the other end of which is attached to a supply of fluid (130 in FIG. 4), such as air.
Positioned within the elongated cavity 64 is an elongated rod or valve stem 88. One end of the valve stem travels within a valve guide 90 defined as part of the end of the elongated cavity 64 where chamber 65 is defined. The other end of the stem 88, after passing through a suitable bushing 95 defined in the end of the cavity 64 where the chamber 67 is located, is secured to the operator disc 44 through the threaded end 91 of the stem 88 and threaded boss 93 formed as part of disc 44. Appropriately positioned along stem 88 is a pair of valve heads 96 and 98. Valve head 96 is associated with valve seat 70, whereas valve head 98 is associated with valve seat 72. In a preferred embodiment, each valve head is generally in the shape of a sphere. It is to be understood that other shapes are contemplated. For example, see FIG. 5a where each valve head is shown having a flat surface 71, associated with a flat valve seat 70'. Further, note FIG. 5b, where the valve heads define a frustoconical surface 71' associated with the chamfered valve seats 70 and 72.
The operation of the pressure translator may be described in the following manner with general reference to FIGS. 2 and 4. In order to measure a parameter which fluctuates in accordance with the process pressure of a fluid in a vessel 110 associated with the process being performed, it is necessary to pass a portion of that fluid into the input chamber 22 of the pressure translator 10. This may be accomplished in either of two ways. An input tube 50 may be provided and fitted directly between the process vessel 110 and the lower body portion 16 of the pressure translator. In the alternative, the pressure translator may be incorporated into the structure defining the process vessel.
At the same time, air under pressure from an air supply 130 is introduced through the air supply line 86 into the valve assembly 60 via a fixed orifice 83 for eventual introduction into the output chamber 24. One such fixed orifice is the double screened jet made by Lee Company, Westbrook, Conn., and bearing product identification No. JET A 1872400H. The restrictor is screened at its input and output so that any contaminants in the air supply do not clog the orifice. It has been observed that, for maximum accuracy, a constant flow of air should be maintained through the valve assembly and the output chamber. This is accomplished by maintaining the supply of air pressure greater than the process pressure. It also has been determined that, when the air supply pressure is about one atmosphere (14.7 psi) greater than the process pressure, the most favorable results are obtained.
With the introduction of the process fluid and the air supply into the appropriate chambers, the operation of the pressure translator takes place as follows. When the process pressure is applied to the input chamber 22, the drive disc 42 and the input diaphragm 36 are forced toward the translator plate 12, causing the fluid between the diaphragm 36 to move to the other side of the translator plate. This causes the output diaphragm 30 and operator disc 44 to move away from the translator plate. The drive disc 42 covers the diaphragm 36 and protects it from damage caused by the entry of fluid into the input chamber 22 via tube 50. Because the drive disc 42 serves a safety function, it is desirable although not absolutely necessary to the present invention.
Since the valve stem 88 is connected directly to the operator disc, the valve stem assembly moves to cause the spherical valve heads 96 and 98 to press up against the valve seats 70 and 72 and thus close both valves (FIG. 3a) so that the air supply flows into the output chamber 24 as indicated by the arrows. Closing the valves causes pressure in the output chamber to increase. When the output chamber pressure is equal to the process pressure, the movement of the fluid within the fluid reservoir stops. In this way, the valve heads 96 and 98 are fixed relative to the valve seats 70 and 72 so that a portion of the air being introduced into the output chamber 24 through the fluid passage 100 is allowed to vent to atmosphere in the following manner with reference to FIG. 3b. The fluid passes through both fluid passageways 76 and 78 with the air in passageway 76 entering the chamber 65 and the air in passageway 78 entering chamber 67. Because of the space created between the valve heads and the valve seats, air is permitted to pass from chambers 65 and 67 into chamber 66 and from chamber 66 through air vent 74 out to atmosphere.
When the output chamber pressure is equal to the process pressure, the valves vent the proper air to atmosphere in order to maintain a pressure in the output chamber equal to the process pressure. When the pressure is decreased in the input chamber, the reverse action takes place, thereby reducing the pressure in the output chamber to equal the pressure within the input chamber. In particular, the operator disc 44 and the output diaphragm 30 are forced toward the translator plate 12, causing the fluid in volume 34 of the fluid reservoir to move into volume 32 via bores 28. This causes the output diaphragm to move toward the translator plate. Because the valve stem 88 is connected directly to the operator disc, the valve stem assembly moves to cause the valve heads 96 and 98 to move away from the valve seats 70 and 72 to open both valves and allow a portion of the fluid to flow out of the output chamber to atmosphere to equalize the pressure between the input and output chambers as shown in FIG. 3c.
An alternative arrangement for the operative connection between the valve stem 88 and the operator disk 44 is illustrated in FIG. 6, where like reference numerals denote like elements.
As can readily be seen, the major difference between the connection as shown in FIG. 6 and the connection as illustrated in FIG. 2 is the replacement of the threaded boss 93 and the threaded end 91 with the magnetic assembly generally designated as 130 in FIG. 6.
In detail, the magnetic assembly 130 comprises a tiny cylindrical magnet 132 having a spherical end 134. The other end 136 of the magnet is received within a small metallic sleeve 138. The other end of the sleeve contains a threaded bore 140 that receives threaded portion 91' of the stem 88. Note that stem 88 is shortened to accommodate the structure associated with the magnetic assembly 130, and that the guide bushing 90 is eliminated with this construction so that the magnet has some freedom of lateral movement about the surface of the operator disk 44. To facilitate this movement, the operator disk contains a polished surface.
The valve stem with magnetic assembly 130 operates in a manner similar to that as previously described with reference to the alternative embodiment as shown in FIGS. 3a, 3b and 3c. In particular, the movement of the valve heads 96 and 98 in response to the movement of the diaphragm 30 is the same. The valve stem 88 with magnetic assembly 130 differs, however, in that the curved surface 134 is free to move about the polished surface of the operator disk 44 during alignment of the valve heads 96,98 within their respective valve seats 71 and 72. The magnetic properties of the magnet 132 are chosen so that the magnet remains in contact with the polished first metal disk 44 during operation of the valve stem.
An alternative arrangement for the operative connection between the valve stem 88 and the operator disk 44 is illustrated in FIG. 7, where like reference numerals denote like elements. As there shown, the magnetic assembly 130' comprises a tiny cylindrical magnet 132' having a spherical end 134'. The other end 136 of the magnet is received within a small metallic sleeve 138'. The other end of the sleeve contains a threaded bore 140 that receives threaded portion 91' of the stem 88. Sleeve 138' includes a central bore 142 within which magnet 132' is slidably received. A spring 144 is positioned within bore 142 of sleeve 138' to bias magnet 132' in a downward direction against disk 44. As shown, magnet 132' is of smaller cross-sectional area adjacent spherical end 134' than it is at end 136 in order to define a shoulder, and it is retained by a cap 146 which can be press fitted on the lower end of sleeve 138' and which has an opening smaller than that of the shoulder to prevent magnet 132' from passing completely through the lower end of the sleeve. As in the FIG. 6 embodiment, stem 88 is shortened to accommodate the structure associated with the magnetic assembly 130', and the guide bushing 90 is eliminated so that the magnet has some freedom of lateral movement about the surface of the operator disk 44. To facilitate this movement, the operator disk contains a polished surface.
The valve stem with magnetic assembly 130' operates in a manner similar to that as previously described with reference to the embodiment shown in FIG. 6. In particular, the movement of the valve heads 96 and 98 in response to the movement of the diaphragm 30 is the same. The curved surface 134 is free to move about the polished surface of the operator disk 44 during alignment of the valve heads 96,98 within their respective valve seats 71 and 72. Spring 144 provides overload protection for the assembly illustrated in FIG. 6 in that further axial movement of magnet 132 can be accommodated within sleeve 138 up to the point where spring 144 is fully compressed. Preferably, spring 144 is provided with a preload of approximately one pound to insure firm contact with the surface of disk 44. Additionally, the magnetic properties of the magnet 132 are selected so that the magnet remains in contact with the polished first metal disk 44 during the full extent of operation of the valve stem.
Also as shown in FIG. 7, direct communication is provided between third chamber 67 and chamber 24 by means of passageways 100. Similarly, direct communication is provided between chamber 65 and chamber 24 by means of equalizing passageway 102, which extends therebetween and which does not intersect with vent port 74.
Another embodiment of the present invention is illustrated in FIG. 8, wherein the housing within which the translator is contained is of a different external and internal configuration to provide a translator having reduced size, weight and assembly time relative to the configuration illustrated in FIGS. 1 through 6. In the embodiment of FIG. 8a generally cylindrical translator housing 150 is provided, the housing being open at each end thereof, and including a pair of spaced radial openings 151, 152, the purpose for which will hereinafter be described. The housing includes a smooth internal bore 153 and an annular slot 154 formed in the bore adjacent each of the open ends thereof.
Positioned within housing 150 and generally centrally of the ends thereof is a translator plate 155 in the form of a disc having an annular input face 156 and an annular output face 157, each of the faces being flat and positioned perpendicular to the axis of plate 155. Inwardly of each of faces 156, 157 is a first generally coaxial depression 158, 159, respectively. Spaced inwardly of the first coaxial depression is a second coaxial depression 160 and 161, respectively. Interconnecting each of second depressions 160, 161, is an axial bore 162, which can be a single bore as shown, or it can be a plurality of generally axially positioned bores which serve to permit communication between the depressions. The outer periphery of translator plate 155 is so sized as to permit it to be snugly yet slidably received within bore 153, substantially in fluid-tight relationship therewith. Additionally, a radially positioned fill port 163 is provided and extends from the periphery of plate 155 to axial bore 162 in order to permit communication therebetween. Translator plate 155 is so positioned within housing 150 that fill port 163 is aligned with radial opening 151.
Positioned in overlying relationship with each of the depressions, and extending radially outwardly to input face 156 and output face 157 of the translator plate are flexible diaphragms 164,165, respectively, adjacent the outer faces of each of which is positioned a supporting disc 166, 167, respectively. As in the embodiments heretofore described, diaphragms 165, 167 can be made of a thin film, such as Mylar, Teflon, or a thin metal foil of stainless steel or brass. A diaphragm formed from Teflon film having a thickness of about 0.002 inches has been found to be particularly advantageous.
Positioned opposite input face 156 of the translator plate is an input chamber member 168, which is a generally disc-like structure having a substantially flat lower surface 169 and an upper surface including a generally axially positioned conical recess 170. An annular contact surface surrounds and is positioned radially outwardly of recess 170 and is disposed opposite annular input face 156 of the diaphragm. Recess 170 and diaphragm 164 define an input chamber 171, that communicates with a flushing conduit 172, through bore 173 which extends through input chamber member 168. Also positioned in the input chamber member are a pair of axially positioned bores 175, 176, which are connected to the respective legs of a U-shaped trap 177. Bore 175 extends through chamber member 168 from recess 171 to lower surface 169 while bore 176 extends only partially into member 168 and connects with a threaded aperture 178 that extends radially inwardly from the outer peripheral surface of input chamber member 168 and is adapted to receive a pressure fitting (not shown) which, in turn, is connected to the process pressure source. Aperture 178 is positioned opposite opening 152 to permit access thereto. U-shaped trap 177 is connected to a drip input conduit 179 that extends outwardly therefrom and which includes a restriction in the form of an orifice 180, which can be a Lee Jet orifice similar to that previously identified but designated Model 200H, and which also includes a check valve 181 that serves to permit flow only in the direction toward the U-shaped trap 177.
The input chamber member is supported axially by means of a plurality of disc springs 182 formed from flexible metallic material, which, in turn, rest on an inwardly extending retaining ring 183 positioned within annular slot 154. The disc springs are of an annular configuration to permit flushing conduit 172 and U-shaped trap 177 to interconnect with bores 173, 175 and 176, respectively.
An output chamber member 184 is positioned on the opposite side of translator plate 155 from input chamber member 168 and is also generally disc-shaped and adapted to be slidably positioned within bore 153. Output chamber member 184 includes a generally cylindrical recess 185 coaxial therewith and which extends radially outwardly to a point inwardly of the peripheral edge thereof to define output chamber 186. A threaded axial bore 187 is provided to receive a generally cylindrical valve body member 188 having an exteriorly threaded neck 189 adapted to mate with the internal threads in bore 187. A retaining ring 190 is positioned within annular slot 154 to prevent upward movement of output chamber member 184, and to provide an upper stop against which the force of disc springs 182 act through input chamber member 168, translator plate 155, and output chamber member 184.
Valve body 188 includes an air inlet connection 191 which incorporates a restriction 192 in the form of an orifice which can be, for example, an orifice manufactured by Lee Jet and identified by model number 400D. Positioned diametrically opposite air inlet 191 is an air outlet 193, which is connected to a suitable pressure measuring device (not shown). Within valve body 188 are positioned first chamber 195, second chamber 196, and third chamber 197, which are generally axially arranged in spaced relationship. Inlet 191 communicates with first chamber 195 by means of passageway 198 and with third chamber 197 and output chamber 186 by means of passageway 199. An equalizing passageway 194 extends from first chamber 195 to output chamber 186 in order to assist in equalization of the pressures within those respective chambers. Valve stem 200 carries spaced valve heads 201 and 202, which are engagable with valve seats 203 and 204, respectively. First and second chambers 195,196, respectively, are in communication by means of passageway 204, within which stem 200 is loosely carried while second and third chambers 196,197, respectively, are in communication by means of passageway 205, which also loosely carries stem 200. The innermost end of stem 200 includes a magnetic assembly 206, which can have the same parts and structure as magnetic assembly 130' illustrated in FIG. 7. Valve body 188 also includes a vent port 207 as is disclosed in connection with the earlier-described embodiments and which extends from second chamber 196 to vent the device to the atmosphere.
As will be appreciated, the operation of the embodiment illustrated in FIG. 8 is similar to that of the other embodiments hereinbefore described, and the same pressure balanced valve assembly is utilized. Additionally, however, a flush system is provided whereby cleaning fluid can be passed into input chamber 171 through flushing conduit 172 and is utilized to clean the process fluid from the input chamber by use of reverse flow. The position of check valve 181 prevents back flow through drip input conduit 179.
The drip system permits pressurized, clean fluid to pass through the orifice and check valve at a very slow rate and out through the input port. This small flow of clean fluid prevents process fluid from entering trap 177 and input chamber 171. If the clean fluid has a lower density than the process fluid, the clean fluid will be in the loop trap and prevent the process fluid from entering the input port at times when there is no pressure on the drip or the flush systems. The operation of the drip system involves closing the flush line by means of a suitable valve (not shown) or the like, and providing pressurized clean fluid to drip input conduit 179. The clean fluid passes through orifice 180, check valve 181 and fills inlet chamber 171, bore 175, U-trap 177 and bore 176. Because process fluid is kept from the input chamber, clogging of the device is eliminated. For example, in oil well drilling operations the process fluid can be a so-called drilling mud, which is a viscous, gummy material which tends to clog instruments after only a short period of operation. However, by providing as the clean fluid the base fluid used to prepare the drilling mud, such as water where water-based drilling muds are employed and diesel oil where oil-based drilling mud are employed, a clean, mud-compatible buffer fluid is used to transmit the process fluid pressure to the input chamber. A continuous supply of the clean fluid is slowly added to the system through drip input conduit 179 to insure that the process fluid does not enter the device. As a result, the number of times the device must be removed from the system for cleaning is substantially reduced, thereby minimizing interruptions to the operation of the process.
The diaphragm system and valve assembly provide for very accurate measurements because the movement of the diaphragm is only a few thousandths of an inch. Once pressure equilibrium is established, there is no flow of fluid within the fluid reservoir between the diaphragms.
A pressure signal is obtained at the port 52 defined in the upper body portion 14. The pressure signal is transmitted via the tube 54 to the measurement device 120. The measurement device is of the type that does not require fluid flow for operation. One such device is the capacitive pressure transducer produced by Kavlico Corporation, Chadsworth, Calif. and bearing product identification No. P614-4.
It is desirable that there should not be any leakage of air from the output chamber 24 to the remote device. In all respects, the pressure translator provides a closed system, and no air movement other than movement of the sensing element in the transducer or the gauge of the remote device should take place. If these conditions are observed, the pressure on one end of the pneumatic line 54 at the measuring instrument will be exactly equal to the pressure in the output chamber 24.
It has been determined that the pressure translator 10 is relatively insensitive to orientation. The valve assembly 60 can operate in a vertical mode, upside down, with the valve seats up or down. The only effect of rotating the valve assembly is a slight offset in the pressure, since the weight of the valve stem, the operator disc, and the fluid within the fluid reservoir act as a small offset to the process pressure. With the valve assembly in a vertical position, with the valve stem set to move in an upward direction, the offset error is negative and reduces the output signal. This error is very small but must be added to the output signal to get a true value for the process pressure. If the valve stem is set to move in a downward direction, the error is positive.
As an example, when measuring two columns of water, one 100 inches high and another 6 inches high, the results may be offset by a quarter of an inch of water in both cases when the valve stem is up. In other words, for 100 inches of water the results would be 99.75 inches and for 6 inches of water the results would be 5.75 inches. If you turn the valve upside down, it would add to the actual process pressure by a quarter of an inch of water. In other words, the two readings would be 100.25 and 6.25 inches of water instead of the actual 100 inches and 6 inches. This is a constant offset that does not vary.
Because of the structure of the pressure translator 10, the effects of temperature are basically cancelled out. A certain amount of expansion of the fluid within the fluid reservoir between the diaphragms is nulled out completely because of the balancing principle which takes place between the diaphragms.
Because of the employment of the diaphragm structure and the isolated pressure chambers 22 and 24, the pressure translator provides protection for the process. When the input diaphragm is flattened against the translator plate 12, all of the holes 28 in the translator plate are closed, thereby preventing passage of air from the output chamber 24 into the process vessel should the diaphragm 36 rupture. The pressure translator also provides protection for both the instrument used for measuring the pressure as well as the process itself. Because the pressure within the output chamber can be no greater than the pressure of the air supply, the remote measuring instrument will be protected from breakage as long as the measuring instrument is rated to withstand such pressure.
It is important that the two valve heads on the valve stem 88 be precisely adjusted to maintain a balanced air flow through the two valve seats. The reason for the balanced value is that any time there is a flow through and around the valve, movement of the air creates a drag force to pull the valve in the direction of flow. The objective of the balanced valve is to split the flow so that exactly half the air is pushing the valve down and the other half is trying to push it up. If the valve is properly adjusted, the two drag forces are cancelled out and thereby eliminate the error caused by the flow of air.
Assuming the balance valve is doing its job to nullify the flow drag forces of the air supply, then the only force that could upset the balance in the chamber would be friction caused by the valve stem touching the valve body. This error is reduced by the air flowing around the valve stem as an air bearing in the valves.
Although the present invention has been shown and described in terms of specific preferred embodiments, it will be appreciated by those skilled in the art that changes or modifications are possible which do not depart from the inventive concepts described and taught herein. Such changes and modifications are deemed to fall within the purview of these inventive concepts.
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A pressure translator for converting a process pressure into a pneumatic signal which can be transmitted and measured by a pressure measurement device at a remote location. The pressure translator provides isolation for the process and the measuring equipment but still translates the process pressure with very high accuracy. The pressure translator employs a balanced valve in cooperation with a forced balanced diaphragm.
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BACKGROUND OF THE INVENTION
This application is related to copending patent application Ser. No. 522,449, now U.S. Pat. No. 4,529,119 which was filed on Aug. 12, 1983 and is assigned to the same assignee as is this application.
This invention relates to a portable and tampering-proof container or cassette for storing currency notes therein, with the cassette being used in association with an automated teller machine (ATM) or a cash dispensing machine, for example.
Stated briefly, to utilize an ATM, a customer inserts an identifying card into the machine to identify his account number, and then he enters certain data on the keyboard of the ATM to further identify himself and to indicate the amount of cash in the form of currency, for example, that he wishes to obtain from the ATM in a typical cash dispensing function. The ATM will then process the transaction, update the user's account to reflect the current cash withdrawal, dispense the requested currency, and return the identifying card to the customer as part of a routine operation.
The currency to be dispensed from an ATM is generally stored in a container or cassette which is inserted into the ATM and which positions the currency or bills to be withdrawn from the container by "picking" apparatus associated with the ATM as part of the routine cash dispensing described previously. Some of these cassettes are lockable and others are non-lockable.
These cassettes are loaded with currency or bills generally at a central bank, and then the cassettes may be turned over to a security firm for delivery in armored vehicles, for example, to a location or branch bank at which an ATM is located. Personnel at the branch bank, for example, then insert the loaded cassette into the ATM.
In order to minimize the theft of currency from the cassettes which are exposed to the various people in the delivery and handling sequence mentioned in the previous paragraph, cassettes which are referred to as "secure" cassettes have been developed. These "secure" cassettes have, generally, complex mechanisms or electrical systems which prevent an unauthorized access into the cassette by the various people mentioned, for example, in the delivery and handling sequence mentioned.
In one prior-art cassette, for example, the associated shutter door (through which the bills pass when the cassette is positioned in operative relationship with an associated ATM) is locked or latched in a closed position after loading it with bills and during transit in the handling sequence mentioned. As the cassette is positioned in operative relationship with the ATM, the shutter door is opened to permit the ATM to "pick" bills therefrom in a routine cash dispensing operation as described. When the number of bills remaining in the cassette reaches a predetermined low amount in normal operations, the ATM prevents further cash dispensing operations and gives an indication that another fully-loaded cassette is required. An authorized person then removes the partially loaded cassette from the ATM prior to loading a fully loaded one therein.
As the partially-loaded cassette is removed from the ATM, the shutter door closes and is latched in the closed position before the cassette is completely removed from the ATM. The cassette is designed so that the shutter door may be opened once (when put into an ATM, for example), and when it is taken out of the ATM, it is latched in the closed position so that it must be returned to the central bank for opening, refilling if necessary, and thereafter setting the associated latch so that it can be subjected to only one cycle of opening and closing as described. The partially-loaded, closed, and latched cassette is then forwarded to the central bank (in the example described) where the cassette is opened, filled with currency, and latched in the closed position.
When a cassette is inserted in an ATM, it is sometimes necessary to remove the cassette in order to clear out certain jams which may occur in the picker mechanism associated with the ATM, for example. When the prior-art cassette mentioned is removed from the ATM, the associated shutter door is latched in the closed position. This means that the cassette has to be returned to the central bank (in the example described) in order to have the cassette opened and re-latched. Because each cassette containing $20 bills, for example, may have up to about 60,000 (U.S.) dollars therein, a considerable amount of money may be involved in such return activities which do not represent a profitable use of money. While these cassettes are referred to as "secure" cassettes, it is obvious that the latch mechanisms mentioned do not prevent someone from taking the cassette and breaking it open to get the currency stored therein. Perhaps these "secure" cassettes should be viewed as efforts to eliminate "sophisticated pilfering" of the currency stored therein.
SUMMARY OF THE INVENTION
This invention relates to a tampering-proof container for storing items, like currency, or sheets, comprising: a housing having first and second openings therein; a first closure moveable between closed and open positions with regard to said first opening; a second closure moveable between closed and open positions with regard to said second opening; a seal to secure said second closure in said closed position and to permit said second closure to be moved to said open position only upon breaking said seal to thereby give an indication that said second closure has been opened; means for storing items within said housing; means for moving said first closure from said closed position to said open position to enable said items to be removed therethrough and for moving said first closure from said open position to said closed position; means for indicating a zero position and a number of times that said first closure has been moved from said closed position to said open position after said seal is applied to said second closure; locking means cooperating with said indicating means for locking said first closure in said closed position when said first closure has been moved to said open position and returned to said closed position a predetermined number of times; and second locking means being movable between locking and unlocking positions within said housing and also said second locking means being movable into said locking position with regard to said first locking means when said first locking means locks said first closure in said closed posision, said second locking means being moveable to said unlocking position only after said seal is broken or disabled and said closure is moved to said open position to enable said first locking means to be unlocked; said second locking means comprising: a first member; means for mounting said first member for movement between said locking and unlocking positions; a second member pivotally mounted in said housing for movement between a first position in said housing and a second position at least partially out of said housing; and a third member connected said first and second members to ennable said first member to be moved from said locking position to said unlocking position only when said second closure is in said open position and said third member is moved out of said housing toward said second position.
The cassette made according to this invention provides a low-cost, simple, tampering-proof cassette which obviates the problems mentioned with some of the prior-art cassettes for storing currency.
These advantages and others will be more readily understood after reading the following description and drawing; accordingly, a list of the advantages will be found at the conclusion of the detailed description of the invention.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a general view, in perspective, of a preferred embodiment of the cassette of this invention as it is being inserted into an ATM;
FIG. 2 is a general view similar to FIG. 1, showing the cassette in operative relationship with the ATM and also showing a bill support structure which supports the currency or bills on edge and resiliently urges the bills towards a picker mechanism associated with the ATM;
FIG. 3 is a plan view of the cassette with the bill support structure removed therefrom to show the tampering proof mechanism associated with the cassette;
FIG. 4 is a cross-sectional view, in elevation, taken along line 4--4 FIG. 3 to show additional details of the cassette;
FIG. 5. is an enlarged, elevational view, taken along the line 5--5 of FIG. 3, to show additional details of the indicator wheel shown in FIG. 3;
FIG. 6 is an elevational view taken along the line 6--6 of FIG. 3 to show additional details of the means for moving the shutter door between the closed and open positions shown in FIGS. 1 and 2, respectively; and
FIG. 7 is a general exploded view, in perspective, of a portion of means for making the cassette tampering proof and the view is taken from the direction of arrow A in FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a general perspective view of the tampering-proof cassette of this invention which is designated generally as 10 and which is shown in a position in which it is to be inserted into operative relationship with an automated teller machine hereinafter referred to as ATM 12. The ATM 12 is conventional such as the NCR 5080, for example, which is available from the NCR Corporation of Dayton, Ohio. The cassette 10 is comprised of a housing 14 having a first closure such as shutter door 16 which is moveable between the closed position shown in FIG. 1 and the open position shown in FIG. 2. The cassette 10 also includes a second closure or lid 18 which is connected to the housing 14 by a hinge 19 and is moveable between the closed position shown in FIG. 1 and the open position shown in dashed outline 18' in FIG. 2. However, it should be pointed out that when the cassette 10 is in operative relationship with the ATM 12, the lid 18 is closed as shown in FIG. 1; FIG. 2 is essentially a diagrammatic showing to facilitate a description of the cassette 10.
The cassette 10 (FIG. 1) also includes a seal 20 which is mounted in a well 21 on the lid 18 to provide a tampering-indicating way of locking the lid 18 in the closed position. Locating the seal 20 in the well 21 presents a flush appearance of the cassette 10 to the ATM 12. The seal 20 includes a steel ring 22 (having a welded joint) which is used to rotate a finger lever (not shown) located under the lid to coact with a flange 24 (FIG. 2) to lock the lid 18 in the position shown in FIG. 1. For example, after the cassette 10 is loaded with currency and prepared for use in an ATM as will be described hereinafter, the ring 22 is pivoted to a vertical plane (as viewed in FIG. 1) and rotated in a clockwise direction to lock the lid 18 in the closed position. Thereafter, ring 22 is moved to the horizontal or flat position shown in FIG. 1 in which a portion of the ring lies between two spaced upright extensions 26 and 28 which are secured to the lid 18. A plastic "wire" (not shown) is then inserted through the openings 30 in the extensions 26 and 28 and "sealed" as is conventionally done with some of the newer plastic seals (not shown) which also have a tab with an identification number thereon to identify a particular seal used on a particular cassette 10 which is sent to a particular ATM 12. The lid 18 cannot be opened unless the seal 20 is broken to permit the "O" ring 22 to be raised to the vertically oriented operating plane mentioned. Breaking the seal 20 is an indication that the lid 18 of the cassette 10 has been opened.
The cassette 10 (FIG. 1) also has side rails, like side rail 30, on opposed sides of the housing 14 to enable the cassette to be aligned and mounted in the frame 32 of the ATM 12. When the cassette 10 is mounted on the frame 32 and pushed in the direction of arrow 34, the cassette 10 engages a stationary actuating mechanism 36 which includes the push rods 38 and 40 (shown only functionally in FIG. 1), which fit into holes 42 and 44, respectively, in the housing 14 of the cassette 10. As the cassette 10 is pushed on the push rods 38 and 40, the shutter door 16 is moved to the open position shown in FIG. 2.
When the cassette 10 is in operative engagement with the ATM 12, as shown in FIG. 2, the shutter door 16 is opened and the first note or bill 46 of the stack 48 of bills is exposed to the picker mechanism 50 which is shown only diagrammatically. The cassette 10 may have to be modified slightly to adapt to different picker mechanisms associated with the ATM 12; however, this aspect may be conventional and does not form a part of this invention.
The cassette 10 is loaded with a stack 48 of bills like 46 which are supported on a conventional bill support structure 52 which is detachably secured to the housing 14 by flanges 54 and 56, for example, which are secured to anchor areas (not shown) inside the cassette 10 so as to enable the support structure 52 to be removed only when the lid 18 is in the open position (shown as 18') in FIG. 2. The support structure 52 includes a back-up plate 58 which is biased by a spring (not shown) to urge the stack 48 of bills towards the picker mechanism 50. The stack 48 of bills is restrained at the open end of the cassette 10 (by conventional means, not shown) so as to enable the picker mechanism 50 to pick successively the first bill 46 in the stack 48 to perform the cash dispensing function mentioned earlier herein. After a bill like 46 is picked, it is transferred by transport mechanisms (not shown) to a receptacle, for example, where additional bills are collected in response to the monetary amount requested, prior to letting the bills become accessible to the customer as a result of a routine cash dispensing transaction.
When the shutter door 16 is moved from the closed position shown in FIG. 1 to the open position shown in FIG. 2, it opens from the top to the bottom as viewed in FIGS. 1 and 2. The shutter door 16 is conventional and is comprised of a plurality of horizontally-positioned slats like 64 and 66 (FIG. 1) which are joined at their long sides to provide a flexible secure closure or door which can be moved under the bill support structure 52 (shown in FIG. 2) when the shutter door 16 is opened. The ends of the slats like 64 and 66 are retained in "U"-shaped channels 236 and 238 (FIG. 3) located within the housing 14 to enable the cassette 10 to be tampering-proof and to provide a guide for moving the shutter door 16 therein. A conventional plastic multifilament tape (not shown) is secured to the slats like 66 and 66 on the inside of the shutter door 16 to give a visual indication when an attempt is made to remove any of these slats during a theft or vandalistic activity. As an alternate construction, the shutter door 16 may be made of slats 64 and 66 which are joined by what is referred to as a "living hinge" so as to provide a one piece construction for the door 16.
FIG. 3 is a plan view of the cassette 10 shown in FIGS. 1 and 2, with the bill support structure 52 being removed therefrom to facilitate a showing of the means for making the cassette 10 secure and the means for moving the shutter door 16 between the closed and open positions mentioned.
The means for moving the shutter door 16 includes the actuating mechanisms 68 and 70 shown in FIG. 3 with mechanism 68 being shown in more detail in FIG. 6. Because the mechanisms 68 and 70 are identical but mirror images of each other, a description of only mechanism 68 will be given.
The actuating mechanism 68 coacts with the associated push rod 40 to positively drive the shutter door 16 between the closed and open positions mentioned. The shutter door 16 extends towards the bottom 74 of the housing 14, is guided at its ends in appropriate channels 236 and 238 (only portions of which are shown in FIG. 3), and is secured to a cross member which is referred to as a truck 76. When the truck 76 is moved to the right from the position shown in FIG. 3, the shutter door 16 is opened, and when it is returned to the position shown in FIG. 3, the shutter door 16 is in the closed position.
The actuating mechanism 68 (FIG. 3) includes a pawl 78 which is pivotally mounted on the truck 76 by stud 80. While the pawl 78 is shown in solid outline in FIG. 3 to facilitate a showing thereof, it is actually located between the truck 76 and the bottom 74 of the housing. The pawl 78 is resiliently biased in a clockwise direction as viewed in FIG. 3 by a tension spring 82 having one end secured to a stud 84 on the pawl 78 and the remaining end thereof secured to a stud 86 on a control rod 88 which is fixed to the truck 76 to move therewith. The control rod 88 has a recess 90 therein to provide clearance for a stud 92 which is fixed to the pawl 78. The stud 92 (FIG. 6) extends towards the bottom 74 of the housing 14 and is aligned to engage the push rod 40 when the cassette 10 is mounted in the ATM 12. The pawl 78 also has a down-turned abutment surface or tang 94 thereon which is moved between the first and second abutment surfaces 40-1 and 40-2 located in a recess 41 in the push rod 40. The pawl 78 also has a down-turned abutment surface or tang 96 thereon which, in the position shown in FIG. 3, is aligned to abut against the end of a bar 98 which is secured to the bottom 74 of the housing 14.
Assuming that the cassette 10 is to be inserted in the ATM 12 in a routine manner, as it is pushed onto the actuating mechanism 36, the associated push rods 38 and 40 engage their associated actuating mechanisms 70 and 68, respectively. The operation of the actuating mechanism 70 is the same as that of actuating mechanism 68; therefore, a discussion of the interaction between push rod 40 and the actuating mechanism 68 only will be discussed.
As the cassette 10 is pushed on the push rod 40 (FIG. 3), its leading edge engages the stud 92 on the pawl 78 causing the pawl 78 to rotate in a counterclockwise direction (as viewed in FIG. 3) against the bias of spring 82. As this rotation of pawl 78 begins, the associated tang 96 moves out of blocking position with the bar 98, and the tang 94 moves into the recess 41 on the push rod 40 between the first and second abutment surfaces 40-1 and 40-2 of the push rod 40. As the cassette 10 is pushed further onto the push rod 40, the pawl 78 is rotated further in a counterclockwise direction until it abuts against a stop 100 (on the truck 76) to provide the driving force to move the truck 76 and the shutter door 16 attached thereto to the right as viewed in FIG. 3. Note that as the push rod 40 is moved to the right (relatively) from the position shown in FIG. 3, it pushes the stud 92 out of the recess 90. Also, after the pawl 78 is rotated against the stop 100, the tang 96 rides on the inside edge 102 of the stationary bar 98; this keeps the pawl 78 from rotating prematurely in a clockwise direction which would release the tang 94 from the push rod 40. The cassette 10 is then pushed all the way on the push rods 40 and 38 to open the shutter door 16 completely and to place the cassette into operative relationship with the ATM 12.
When the cassette 10 is to be removed from the ATM 12, the cassette 10 is pulled off the push rod 40 (and push rod 38), and as it is pulled off, the tang 94 engages the second abutment surface 40-2 to move the truck 76 towards the left to the home position shown in FIG. 3, in which position the shutter door 16 is in the closed position. Note that the tang 94 stays in engagement with the second abutment surface 40-2 (because of the tang 96 riding on the side 102 of bar 98) to positively return the shutter door 16 to the home position. After the shutter door 16 is closed and the cassette 10 is near to being pulled off the push rods 38 and 40, the tang 96 of the pawl 78 will clear the bar 98 permitting the pawl 78 to rotate in a clockwise direction (as viewed in FIG. 3) permitting the tang 94 to move out of the recess 41 in push rod 40, permitting the cassette 10 to be pulled free of the push rods 40 and 38. The pawl 78 has an arcuately-shaped leg 104 which rides on the top surface 106 of the bar 98 to provide stability to the pawl 78.
The actuating mechanism 70 (FIG. 3) operates in the same manner as does actuating mechanism 68, and the mechanism 70 includes the same parts as does mechanism 68 except for the mirror-like aspect mentioned earlier herein. Accordingly, the parts in mechanism 70 are given the same reference numbers as corresponding parts in mechanism 68 except for the addition of a (-1) which follows the part. In other words, actuating mechanism 70 has a pawl 78-1, tang 94-1, tang 96-1, control rod 88-1, spring 82-1, and bar 98-1.
Having described the actuating mechanisms 68 and 70 in FIG. 3 for moving the shutter door 16 between the closed and open positions mentioned, it appears appropriate to discuss some of the means 109 (FIG. 3) for making the cassette 10 tampering-proof. The means 109 includes the cross bar or truck 76 which has a camming lever 108 fixed thereto to move therewith in the directions of double arrow 110 and also includes the bell crank lever 112 which is pivotally mounted on a pin 114 which is upstanding from and fixed to the bottom 74 of the housing 14. A stud 116 is fixed to the underside of bell crank lever 112 to coact with a cam surface 118 on the camming lever 108. When the camming lever 108 moves to the right, as viewed in FIG. 3, as the shutter door 16 is being opened, the cam surface 118 and stud 116 coact to rotate or pivot the bell crank lever 112 in a counterclockwise direction.
The counterclockwise pivoting of crank lever 112 (as viewed in FIG. 3) performs two general functions. First, it actuates a pawl 120 associated with an indicator wheel 122, and secondly it moves a slide member 124 out of the side wall 126 of the housing 14 to coact with an abutment member 128 associated with the frame of the ATM 12 to prevent the cassette 10 from being withdrawn from the ATM until the shutter door 16 is closed.
Starting with the function of the crank lever 112 associated with the indicator wheel 122, one end 130 of the lever 112 is pivotally joined to one end of a link 132 whose remaining end is pivotally joined to the pawl 120 by a pin 134. The pawl 120 is pivotally mounted on a stud 136 which is secured to and is upstanding from the bottom 74 of the housing 14. When the crank lever 112 is rotated in a counterclockwise direction as viewed in FIG. 3, the pawl 120 rotates in a clockwise direction, causing the tooth 138 on the pawl 120 to engage one of the teeth like 140 on a ratchet wheel 142 which is part of the indicator wheel 122 as seen better in FIG. 5. As the tooth 138 on the pawl 120 moves towards a tooth like 140, the centering tooth 144 on the pawl 120 moves out of engagement with the ratchet wheel 142 (FIG. 5) permitting the pawl 120 to index the ratchet wheel 142 one tooth or one position in a counterclockwise direction as viewed in FIG. 3. For the moment, it is sufficient to state that when the cassette 10 is removed from the ATM 12, the crank lever 112 will be rotated, slightly, in a clockwise direction and the pawl 120 will be rotated in a counterclockwise direction to move the centering tooth 144 into engagement with the ratchet wheel 142 while the tooth 138 on the ratchet 120 is moved out of engagement with the ratchet wheel 142 on the indicator wheel 122.
The indicator wheel 122 also has a top wheel 146 and a lower wheel 148 as shown best in FIG. 5. The lower wheel 148 has two recesses like 150 therein adjacent projections or ears 151 (FIG. 3) which are spaced 180 degrees apart. The numbers on the top wheel 146 are visible through a window 152 (FIG. 3) located in back wall 154 of the housing 14. The indicator wheel 122 gives an indication of the number of cycles in which the shutter door 16 has been opened and closed. The ratchet wheel 142, the top wheel 146, and the lower wheel 150 (FIG. 5) are indexed as a unit and are rotatably supported on a short axle 156 (FIG. 5) which is secured to and is upstanding from the bottom 74 of the housing 14.
The cassette 10 is designed to permit the number of cycles of opening and closing the shutter door 16 to be set from one to six, for example. Assume that the indicator wheel 120 is set (as will be explained hereinafter) to permit six such cycles. As the pawl 120 indexes the indicator wheel 122 for six indexes (with the number "6" showing in window 152 shown in FIG. 3) a tang 158 on one arm of a second bell crank lever 160 will drop into the nearest one of the two 180 degree-spaced recesses 150, permitting the crank lever 160 to rotate slightly in a clockwise direction as viewed in FIG. 3 (after the cassette 10 is removed from the ATM 12 as will be described hereinafter). Except for dropping into the recesses 150, the tang 158 rides on the periphery of the lower wheel 148. When the crank lever 160 rotates slightly, (in the clockwise direction mentioned) on its pivoting stud 162, its other arm 164 moves a link 166 (to which it is pivotally connected by a pin 170) upwardly as viewed in FIG. 3. The link 166 has an extension 166-1 which permits the end 188 of control rod 88 to slide under the link 166 without abutting thereagainst when the end 188 moves to the right. The arm 164 also has a blocking tang 168 on its end. A third crank lever 172, which is pivoted on a stud 174 (upstanding from and secured to the bottom 74 of the housing 14) is also pivotally secured to the link 166 to receive the upward motion mentioned from the crank lever 160. The crank lever 172 also has a blocking tang 176 on its arm 178 and its other arm 180 has an actuating post or handle 182 upstanding therefrom as seen best in FIG. 4. A spring 184 (secured to the arm 180 and a stud 186 upstanding from the bottom 74 of the housing 14) is used to bias the crank lever 172 in a clockwise direction as viewed in FIG. 3, and because crank levers 172 and 160 are joined by link 166, the crank lever 160 is biased by spring 184 to rotate in a clockwise direction to enable its associated tang 158 to ride on the periphery of the lower wheel 148 (FIG. 5) and to drop into one of the two recesses 150 when one is presented to the tang 158. When the tang 158 drops into one of the recesses 150, it means that the predetermined number of cycles of opening and closing the shutter door 16 has been reached and further opening of the shutter door 16 is to be blocked. This blocking is effected when the crank lever 160 rotates clockwise due to tang 158 dropping into a recess 150. Because crank lever 172 is linked to crank lever 160, it too will rotate clockwise slightly with crank lever 160, and the tangs 168 and 176 on crank levers 160 and 172 will line up, respectively, in blocking relationship with the ends 188 and 190 of control rods 88 and 88-1, respectively (after the shutter door is closed). This, means that the shutter door 16 cannot be opened until the seal 20 (FIG. 1) on the lid 18 of the cassette 10 is broken, the lid 18 raised, and the indicator wheel 122 reset by a technique to be later described herein. The ends 188 and 190 of the control rods 88 and 88-1, respectively, are slidably supported in apertured, upturned flanges 192 and 194, respectively, of an elongated plate 196 which is secured to the bottom 74 of the housing 14.
The means 109 for making the cassette 10 tampering-proof also includes a locking lever means 198 (FIGS. 3, 4, and 7) to permit changing the position of the indicator wheel 122 under certain conditions to be later described herein. The locking lever means 198 includes a vertically-aligned member 200 having an elongated slot 202 therein in which a horizontally-positioned fastener 204 is located. The fastener 204 is upstanding from the back wall 154. The locking lever means 198 also includes an "L"-shaped lever 206 and a link 208 shown best in FIGS. 4 and 7. The lever 206 has one end pivotally joined to the fastener 204, and the remaining end 206-1 is offset as shown in FIG. 7 and is positioned close to the lid 18 (shown only partially in cross section in FIG. 4). The link 208 has one end thereof pivotally joined to the member 200 by a pin 209, and the remaining end of link 208 is pivotally joined to lever 206 by a pin 210. In the embodiment described, the pins 209 and 210 are located approximately equidistantly from the stationary fastener 204. A tension-type spring 211, connected between the pin 209 and the fastener 204, is used to resiliently bias the member 200 downwardly as viewed in FIG. 4. The lower end of member 200 has a shoulder 212 thereon which rests on end 214 of crank lever 172 (seen better in FIGS. 3 and 7). The lower end and shoulder 212 of member 200 pass through a slot 216 (FIG. 4) in the bill support structure 52, and the fastener 204 and the slot 216 cooperate to enable the member 200 to be reciprocated in a vertical direction. The upper end of the member 200 has a broadened area 200-1 which is located just below the lid 18 when the shoulder 212 rests on the end 214 of the crank lever 172. The operation of the locking lever means 198 just described will be discussed later herein in conjunction with the indicator wheel 122.
When the predetermined number of cycles of opening and closing the cassette 10 has not been reached via the indicator wheel 122, the locking lever means 198 is in the position shown in FIGS. 3, 4, and 7. In this position, the shoulder 210 of the member 200 rests on a corner of the end 214 of crank lever 172 as a result of the downward biasing of spring 211. The lower end of member 200 passes through a slot 216 (FIG. 4) in the bill support structure 52 as previously described. When the predetermined number of cycles of opening and closing the shutter door 16 has been reached, the tang 158 (FIG. 3) drops into the slot 150 (FIG. 5) on the lower wheel of the indicator wheel 122 (after the shutter door 16 is closed), causing crank levers 160 and 172 to rotate in a clockwise direction (as viewed in FIG. 3) as previously explained. The clockwise rotation of crank lever 172 (as viewed in FIG. 3) causes its tang 176 to move into blocking relationship with the end 190 of control rod 88-1 and also causes the end 214 of crank lever 172 to move out from under the shoulder 212 of member 200 (by moving to the right as viewed in FIG. 4), permitting the spring 211 to urge the member 200 in a downward direction as viewed in FIG. 4 to thereby block crank lever 172 from rotating in a counterclockwise direction as viewed in FIG. 3; this keeps the shutter door 16 locked in the closed position.
To reset the cassette 10 after the shutter door 16 is locked in the closed position as mentioned in the previous paragraph, it is necessary to break the seal 20 on the lid 18 and open the cassette 10. In a routine operation, the cassette 10 would then be loaded with a stack 48 of bills 46, and the cassette 10 reset and sealed. To reset the cassette 10, the lid 18 must be up to enable a service person to pivot the L-shaped lever 206 in a counter-clockwise direction (as viewed in FIG. 4) about fastener 204. When lever 206 is so pivoted to the position shown by dashed outline 206-1; it moves the member 200 upwardly, (as viewed in FIG. 4) to the dashed position shown by 200-1' to move the lower end and shoulder 212 of member 200 out of blocking engagement with the end 214 of crank lever 172. While the member 200 is held upwardly with the fingers of the right hand, for example, of a service person, the middle finger of the person's left hand is used to push the actuating handle 182 (which extends above the bill support structure 52) to rotate crank lever 172 in a counterclockwise direction, as viewed in FIG. 3, and thereby clear the tang 158 from a recess 150 and an associated ear 151. The ears 151 prevent the indicator wheel 12 from being reset without giving an indication; this resetting could develop by excessive "play" in the mechanism described which would permit the tang 158 (FIG. 3) to be withdrawn from a recess 150 and would permit the wheel 122 to be rotated to change the number of "cycles".
While still pushing on the actuating handle 182 with the middle finger of the left hand, the left thumb of the service person is used to push the operating handle 220 (upstanding from the pawl 120) to index the pawl 120 (by rotating it clockwise as viewed in FIG. 3) one position to enable the tang 158 to ride on the periphery of the lower wheel 148 as previously described, which positions the crank levers 160 and 172 in the non-blocking positions shown in FIG. 3. Once the crank lever 172 is in the non-blocking position shown in FIG. 3, the vertically-aligned member 200 may be released. When released, the spring 211 urges the member 200 downwardly (as viewed in FIG. 4) causing the shoulders 212 to rest on the top surface of end 214 of crank lever 172.
Continuing with what has been described in the previous paragraph, the top wheel 146 of the indicator wheel 122 has a green area positioned at window 152 (FIG. 3) at this time to be visible from outside the cassette. The lid 18 of the cassette 10 may then be closed and sealed as previously described, and it is ready for use in an ATM 12. Prior to inserting the cassette 10 in an ATM 12, the operator checks the window 152 (FIG. 3) and sees the green indication which means (in the embodiment described) that the shutter door 16 has not been opened since the cassette was sealed.
When the cassette 10 is placed in an ATM 12, the actuating mechanism 36 in association with the means 109 (FIG. 3) for indicating tampering will cause the indicator wheel 122 to index one position as previously described. Assume a routine operation with no problems; under this circumstance, the cassette 10, when empty or low on bills, will show a white color at the window 152. The white color indicates one cycle of opening and closing which represents a routine operation, and therefore, the cassette 10 may be routinely replenished as previously described.
In the example being described, if the cassette 10 with green color in window 152 is placed in an ATM 12, the opening of shutter door 16 will cause the white color to be displayed. If, however, a jam or malfunction occurs in the dispensing of bills 46, it may be necessary to remove the cassette 10 from the ATM 12 to fix the jam, for example. When the cassette 10 is replaced into operative engagement with the ATM 12, the actuating means 46 will initiate the change in cycles recorded on the indicator wheel 122 causing the number "2" to be displayed at window 152. If the cassette 10 and ATM 12 perform thereafter without malfunction, the ATM 12 will indicate (via its display for example) that the cassette 10 has to be refilled. When the cassette 10 is removed from the ATM, the number "2" will still be displayed at window 152. When the cassette 10 is returned to the central bank for refilling (in the example described), it must be accompanied by an explanation as to why an "extra" cycle (as evidenced by number "2") of opening and closing of the cassette 10 has occurred. In this situation, a note or explanation by the serviceperson who repaired the malfunction might be adequate. The ATM 12 itself may provide an indication of the number of times a cassette 10 has been inserted and removed from the ATM 12 to provide a correlation with the cycles recorded on the cassette 10.
In the embodiment described, the cassette 10 may be set to record up to six cycles of opening and closing of shutter door 16 as described. When the cassette 10 is set with green color showing, it means that the image viewed through the window 152 will present a white color for one such cycle, a "2" for two cycles, etc., up to a "6" for six such cycles. This series of colors and numbers is arranged and repeated between each of the slots 150 on the top wheel 146 (FIG. 5) to facilitate a setting of indicator wheel 122. If the cassette 10 is to be set (prior to sealing) to permit only two cycles of operating before locking, for example, the pawl 120 is indexed until the number "4" appears at window 152. When the cassette 10 is installed on an ATM 12, the number "5" will appear at window 150 indicating the shutter door 16 has been opened. If the cassette 10 is removed from the ATM 12 to correct or fix a malfunction and thereafter it is installed in the ATM 12, the actuating means 36 will move the truck 76 and control rods 88 and 88-1 as previously described to index the pawl 120 as previously explained to show a "6" at window 152. When the control rods 88 and 88-1 are pushed to the right as viewed in FIG. 3, the end 190 of control rod 88-1 passes by the tang 176 on crank lever 172 (preventing it from rotating) to thereby prevent the tang 158 on crank lever 160 from dropping into a recess 150; this permits the actuating means 36 to open the shutter door 16. When the cassette 10 is thereafter withdrawn from the ATM 12, the end 190 of control rod 88-1 will be pulled to the left to the position shown in FIG. 3, thereby permitting the tang 158 to drop into a recess 150 as previously explained to lock the shutter door 16 in the closed position, requiring the seal 20 to be broken to unlock the locking lever 198.
The second function of the crank lever 112 (FIG. 3) alluded to earlier herein was to activate the slide member 124. The slide member 124 has an elongated slot 222 therein through which passes a stud 224 which is upstanding from and secured to the bottom 74 of the housing 14. The remaining end 226 of the slide member 124 is slidably mounted in a plate 228 secured to the side wall 126 of the housing 14. The slide member 124 has a stud 230 upstanding therefrom to coact with the slotted end 232 of the crank lever 112. A tension spring 234 is used to bias the slide member 124 downwardly, as viewed in FIG. 3, to withdraw the end 226 thereof inside the housing 14. When the crank lever 112 is rotated in a counterclockwise direction (as viewed in FIG. 3) as the cassette 10 is being installed in the ATM 12, a portion of the cassette 10 will be moved to the left of the abutment member 128 (relatively) before the crank lever 112 rotates sufficiently to push the end 226 of the slide member 124 out of the side wall 126 to position the end 226 of the slide member 124 to the right of the abutment member 128. The cassette 10 thereafter, cannot be removed from the ATM 12 until its shutter door 16 is moved to the closed position. When the shutter door 16 is closed, the end 226 of the slide member 124 is withdrawn within the housing 14, permitting the cassette 10 to be removed from the ATM 12. The shutter door 16 is guided in conventional guides 236 and 238 which are shown only partially to illustrate the function.
The advantages of the cassette 10 in addition to those cited earlier herein are as follows: Some of the prior-art "secure" cassettes are subject to pilfering of the currency therein by inserting wires through the first closure, like shutter door 16, to alter the count of cycles on the indicator wheel 122 (FIG. 3) after taking some currency out. Such wires and techniques cannot be used on the cassette 10 because the lid 18 must be raised (after breaking the seal 20) in order to alter the count of cycles on the indicator wheel 122. Notice that the L-shaped lever 206 must be pivoted in a counter clockwise direction (as viewed in FIG. 4) out of the cassette 10 in order to permit the member 200 to be raised to the non-blocking position to permit the indicator wheel 122 to be reset. The L-shaped lever 206 and the link 208 provide an interference which prevents member 200 from being raised unless the seal 20 is broken and the lid 18 is raised.
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A tampering-proof container for storing currency for use in conjunction with an automated teller machine (ATM). The currency door of the container through which the currency passes when the container is mounted on an ATM is moved positively between the open and closed positions when on the ATM. An indicator wheel within the container gives an indication or count of the number of times the currency door has been opened and closed to provide a check on potential sophisticated pilfering. When the count on the indicator wheel reaches a programmed predetermined amount, the currency door is locked in a closed position with first and second locking linkage inside the container locking the currency door in the closed position. A seal on a loading door on the container must be broken to gain access to the inside of the container to unlock the first and second locking linkage and to reset the indicator wheel. Special linkage, including an "L"-shaped lever which must be pivoted at least partly outside the housing of the container, insures that the unlocking of the first and second locking linkage is effected only when the loading door is opened.
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CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims the benefit of priority from earlier Japanese Patent Application No. 2012-266465 filed on Dec. 5, 2012, the description of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field of the Invention
[0003] The present invention relates to a method and a system for estimating an attitude of a camera.
[0004] 2. Related Art
[0005] In recent years, mobile devices having a large amount of processing for computing power, such as smartphones, have become rapidly popular. Most of these information terminals include a camera as an imaging device. The information terminals provide communication features that simply use audio information and text information. In addition, the information terminals also include communication features that use image information. In accompaniment with the growing popularity of such mobile devices, users are becoming increasingly familiar with technology referred to as augmented reality (AR) and technology for restoring a three-dimensional shape of a subject from captured images. In AR technology, for example, when an image of a target object is captured by the camera in the information terminal, a comment related to the target object is superimposed on the image and displayed. For example, the following non-patent reference 1 reports a method for three-dimensional measurement using a red, green, blue, and depth (RGB-D) camera.
[0006] In technologies such as those described above, calibration of a coordinate system of an environment captured in a two-dimensional image and a coordinate system of an actual environment is performed. To perform the calibration, the position and the attitude of the user (camera) is required to be known.
[0007] Therefore, in the field of AR technology, a following method is proposed. In the method, a marker of which the position, shape, and color are already known is disposed in advance in the actual environment. An image of the marker is captured by the camera. The attitude of the camera is then estimated by the image being analyzed. Since the past, a rectangular marker has often been used as such a marker (for example, refer to the following non-patent reference 2).
[Non-patent reference 1] Lieberknecht S., Huber A., Ilic S., Benhimane S., “RGB-D Camera-based Parallel Tracking and Meshing,” The 10th IEEE and ACM International Symposium on Mixed and Augmented Reality, Oct. 26-29 (2011) [Non-patent reference 2] Kato, et al., “An Augmented Reality System and its Calibration based on Marker Tracking,” Journal of the Virtual Reality Society of Japan, Vol. 4, No. 4, pp. 607-616 (1999))
[0010] To calculate the attitude of the RGB-D camera using the marker, first, the rectangular area of the marker is recognized by the RGB-D camera. Then, the camera attitude is estimated using the coordinates of the apexes of the rectangle.
[0011] However, three-dimensional space has a front/back relationship in addition to the two-dimensional relationships that are up/down and left/right. Therefore, a state occurs in which an object that is present in front hides a subject that is behind it. This state is referred to as occlusion. In an environment having numerous cables and components, these cables and components cause occlusion to occur at numerous perspectives. When a portion of the marker is hidden as a result of occlusion, detection of the rectangular area becomes difficult. Accurate estimation of the camera attitude becomes difficult.
SUMMARY OF THE INVENTION
[0012] The present invention has been achieved in light of the above-described issues. An object of the present invention is to provide a method for enabling estimation of a camera attitude with high accuracy even in an environment in which occlusion occurs, and a system for performing the method.
[0013] To solve the above-described issues, a method for estimating a camera attitude of the present invention is a method for estimating an attitude of a camera with high accuracy. The camera is capable of acquiring an intensity image and a depth image. The method includes: a step of collecting information on images captured by the camera in an environment in which a planar marker is disposed; a step of calculating a position of the planar marker from images in which the planar marker is captured without occlusion; a step of extracting localized feature points for calculating a camera attitude for each frame from the intensity image and the depth image of each frame acquired by imaging; a step of performing association between the extracted feature points, one-to-one between frames, based on a distance between descriptors; a step of estimating an approximate camera attitude during imaging of a specified frame in which a marker hidden by an occlusion is captured, based on the association between the feature points; a step of predicting an approximate position of the marker in relation to the specified frame based on the position of the marker and the approximate camera attitude; a step of converting a three-dimensional point included in the depth image of the specified frame to a world coordinate system using the approximate camera attitude, and extracting a point group within a predetermined distance from the predicted approximate position of the marker; and a step of re-estimating the camera attitude during imaging of the specified frame by determining a camera attitude that optimizes an evaluation function of which a condition is a distance between marker neighboring points included in the point group and an estimation plane on which the marker is positioned.
[0014] In addition, a system for estimation of a camera attitude of the present invention is a system for estimating a camera attitude with high accuracy by performing the method of the present invention. The system includes a camera that captures images of an actual environment in which a planar marker is disposed, and a computer that performs processing of the images captured by the camera. The camera is capable of acquiring an intensity image and a depth image. The computer includes a calculating section that performs steps included in the method of the present invention.
EFFECTS OF THE INVENTION
[0015] In the method for estimating a camera attitude of the present invention, first, based on a position of the marker that has been previously detected and an approximate camera attitude during imaging of the current frame, an approximate position of the marker in relation to the current frame is predicted. A point group is determined by points (marker neighboring points) present near the predicted marker position being extracted.
[0016] Then, a camera attitude (rotation matrix and translation matrix) that optimizes an evaluation function of which a condition is the distance between a marker neighboring point included in the point group and an estimation plane on which the marker is positioned is determined. As a result, the camera attitude is re-estimated.
[0017] The point group includes a significantly large number of points that have been extracted from near the marker. Therefore, estimation of the camera attitude can be performed with significantly high accuracy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In the accompanying drawings:
[0019] FIG. 1 is a conceptual diagram for facilitating understanding of a method for estimating camera attitude of the present invention;
[0020] FIG. 2 is a flowchart for describing the steps in an example of the method for estimating camera attitude of the present invention;
[0021] FIG. 3 is a diagram for explaining numbers of four apexes of a rectangular marker and size 2θ of the rectangular marker; and
[0022] FIG. 4 is a diagram for explaining an area used to judge whether or not a point f m k is near the marker, the point f m k being a three-dimensional point h m k of a depth image of an image k converted to a common coordinate system (world coordinate system).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] A method and a system for estimating an attitude of a camera of the present invention will be described with reference to the drawings.
[0024] As described above, three-dimensional space has a front/back relationship in addition to the two-dimensional relationships that are up/down and left/right. Therefore, a state occurs in which an object that is present in front hides a subject that is in the back. When a portion of a marker is hidden as a result of occlusion, detection of a rectangular area becomes difficult. Accurate estimation of the camera attitude becomes difficult.
[0025] Therefore, first, based on a position of the marker that has been previously detected and an approximate camera attitude during imaging of a current frame, an approximate position of the marker in relation to the current frame is predicted. A point group is determined by points (marker neighboring points) present near the predicted marker position being extracted.
[0026] The points included in the point group can be considered to be a part of the marker. However, in an instance in which the marker is a plane, these points should be on the same plane as the point group of the marker that has been previously detected. Therefore, a distance from a marker neighboring point included in the point group to the plane on which the marker is positioned can be considered to be an estimation error between the approximate camera attitude and the true camera attitude.
[0027] Based on this knowledge, in the present invention, an evaluation function (cost function) is defined. A condition of the evaluation function is the distance from t the marker neighboring point included in the point group to the marker plane. The camera attitude is re-estimated by the attitude of the camera (rotation matrix and translation matrix) that optimizes the evaluation function being determined. The point group includes a very large number of points extracted from near the marker. Therefore, the camera attitude can be estimated with very high accuracy.
[0028] FIG. 1 is a diagram of a conceptual system for facilitating understanding of the method for estimating an attitude of a camera according to an embodiment of the present invention. The camera is attached to, for example, the arm of an industrial robot.
[0029] In FIG. 1 , reference numbers 10 and 10 ′ each represent a camera. The attitudes of the cameras 10 and 10 ′ differ. Reference number 20 represents a plane on which the marker is positioned (estimation plane). Reference number 30 represents an occlusion. Reference number 4 Q represents a judgment area (described hereafter) for extracting points near the marker. Triangular symbols in FIG. 1 indicate a point group of a marker area in a previously captured image. Circular symbols indicate a point group (a point group selected from near the previous marker area) of a marker area in an image that has been newly captured. In the present invention, a distance between the point group and the marker plane (estimation plane) is considered to be an “error” in the camera attitude.
[0030] FIG. 2 is a flowchart for explaining the steps in an example of the method for estimating an attitude of a camera of the present invention. The steps are performed by, for example, a computer (central processing unit [M]).
[0031] Details of processing performed at each step will be described hereafter.
[0032] [Input Image Set] (Step S 101 )
[0033] First, in an environment in which the planar marker is disposed, a plurality of images (N images) are captured from different camera attitudes. The images are then inputted into the computer. The marker is merely required to be capable of allowing the camera attitude to be accurately determined from an image. In the description hereafter, the marker is assumed to be a rectangular marker that is often used in AR.
[0034] Here, the camera used to capture images herein is a camera capable of acquiring an intensity image and a depth image. Here, the camera is an RGB-D camera that is capable of acquiring RGB intensity information for each pixel and distance information on the distance to a subject. In other words, as a result of imaging by the RGB-D camera, the RGB intensity information for each pixel and distance information on the distance to the subject are acquired from the plurality of images captured of the disposed marker. A collection of these images is φ, below.
[0000] Φ={1, . . . , N} [Formula 1]
[0035] The RGB-D camera is, for example, KINECT (manufactured by Microsoft) (registered trademark) or XTION Pro LIVE (manufactured by ASUS) (registered trademark). An RGB camera and a depth camera are fixed to these cameras. When calibration is performed of the relative positional attitudes of the RGB camera and the depth camera, the RGB intensity value for each pixel and the information on the so distance to the subject can be acquired.
[0036] [Calculate Local Features] (Step S 102 )
[0037] Local features for determining an approximate camera attitude are calculated from the images included in the image collection φ. An algorithm for calculating such local features is, for example, scale-invariant feature transform (SIFT) or speeded up robust features (SURF). Taking image k for example, a three-dimensional position M k and a descriptor D k are obtained as described below for an I k -number of feature points. In other words, the RGB intensity information and the distance information on the distance to the subject are extracted from the above-described plurality of images.
[0000] M k ={m i k |i= 1, . . . , I k },m i k =[m x,i k ,m y,i k ,m z,i k ] T [Formula 2]
[0000] D k ={d i k |i= 1, . . . , I k} [Formula 3]
[0038] [Perform Association Between Images] (Step S 103 )
[0039] Next, association is performed between feature points included in a single image among the plurality of images and feature points included in another image. The association is performed between extracted feature points, one-to-one between images, based on distance in feature quantity space. In an instance in which a feature point i included in the image k and a feature point j included in an image h indicate the same point in an environment, the distance D (d i k ,d j k ) between descriptors of the local features calculated at Step S 102 becomes small. Therefore, as a result of thresholding of the distance D between descriptors, feature points in differing images can be associated with each other. Association of the feature points in the image collection φ is placed as in ψ, below. However, association is not performed between the same feature points and in the same image.
[0000] Ψ={ i,j,k,h )| D ( d i k ,d j h )<threshold, iεD k ,jεD h ,k≠h,kεΦ,hεΦ} [Formula 4]
[Calculate Approximate Camera Attitude] (Step S 104 )
[0040] Here, an approximate camera attitude of when the image k is captured is placed at (R c k , t c k ). R c k is a rotation matrix. t c k is a translation matrix.
[0041] A cost function E I is defined as follows. The approximate camera attitude (R c k , t c k ) is determined such as to minimize the cost function E I .
[0000]
E
I
=
∑
(
k
,
h
,
i
,
j
)
∈
Ψ
(
ɛ
ij
kh
)
T
(
ɛ
ij
kh
)
[
Formula
5
]
[0042] Here, ε ij hk is defined as follows.
[0000]
ɛ
ij
kh
=
[
ɛ
x
,
ij
kh
ɛ
y
,
ij
kh
ɛ
z
,
ij
kh
]
=
v
i
k
-
v
j
h
[
Formula
6
]
v
i
k
=
R
C
k
m
i
k
+
t
C
k
[
Formula
7
]
[0043] The above-described ε ij hk is a difference between the coordinates of associated feature points. Therefore, the approximate camera attitude (R c k , t c k ) at which the image k has been captured is estimated from the cost function E I obtained from the difference between the coordinates of the associated feature points.
[0044] Calculation for minimization of the cost function E I is performed by a non-linear optimization method. For example, the Levenberg-Marquardt method can be used. During this calculation, robust estimation for preventing erroneous corresponding points is introduced. The robust estimation is, for example, M-estimator (robust estimation) or random sample consensus (RANSAC). However, because these methods are commonly used, descriptions thereof are omitted herein.
[0045] The accuracy of the approximate camera attitude (R c k , t c k ) obtained by the above-described procedures is dependent on the number of associated feature points per image. Accuracy becomes poor if the number of associated feature points is small. In general, the number of associated feature points is several tens per image. Therefore, estimation of the camera attitude with high accuracy is often difficult.
[0046] Therefore, the camera attitude at which the image k has been captured is re-estimated by the following procedures. Points near the marker detected in the image k are extracted as a point group based on the approximate camera attitude. The evaluation function of which a condition is the distance from a marker neighboring point included in the point group to the plane on which the marker is positioned, is optimized.
[0047] [Calculate Representative Attitude of Marker] (Step S 105 )
[0048] The marker is captured in a plurality of images. Therefore, a representative position (representative attitude) of the marker is determined by calculation. A collection Ξ placing an R-number of markers in the environment is placed as follows. An identifier (ID), from 1 to R, is set for each marker. The ID allows identification by texture.
[0000] Ξ={1, . . . , R }[Formula 8]
[0049] Taking marker r as an example, a representative position of the marker r is determined. The attitude of the marker captured in the image and the marker ID can be determined by a known method.
[0050] For example, apex coordinates (camera coordinate system) of the rectangular marker when the marker r is detected in the image k is placed as in Q k,r below.
[0000] Q k,r ={q λ k,r |λ=1, . . . ,4}
[0000] q λ k,r =[q x,λ k,r ,q y,λ k,r ,q z,λ k,r ] T [Formula 9]
[0051] As shown in FIG. 3 , 1 to 4 of the subscript λ, above, expresses the numbers of the four apexes of the rectangular marker.
[0052] When the rectangle size of a marker model expressing the true shape of the marker is 2θ (mm), the coordinates of the apexes can be expressed by the following expressions.
[0000] q 1 =[−θ,0,θ] T
[0000] q 2 =[−θ,0,−θ] T
[0000] q 3 =[θ,0,−θ] T
[0000] q 4 =[θ,0,θ] T [Formula 10]
[0053] To calculate a representative position W r of the marker, coordinates (R m r , t m r ) that minimize the cost function E 1 , below, are determined.
[0000]
E
M
r
=
∑
k
∑
λ
(
e
λ
k
,
r
)
T
(
e
λ
k
,
r
)
e
λ
k
,
r
=
(
R
C
k
q
λ
k
,
r
+
t
C
k
)
-
(
R
M
r
q
_
λ
+
t
M
r
)
[
Formula
11
]
[0054] Calculation for minimization of the cost function E M r can be performed by a non-linear optimization method or a linear optimization method. For example, the Levenberg-Marquardt method can be used.
[0055] When the coordinates (R M r , t M r ) are determined, the representative position W r of the marker can be calculated as follows.
[0000] W r ={R M r q λ +t M r |λ=1, . . . ,4} [Formula 12]
[0056] [Extract Point Group Near Marker] (Step S 106 )
[0057] All three-dimensional points Y k of the depth image of the image k are placed as described below. In other words, all three-dimensional points h m k included in the depth image of the image k are determined.
[0000] h m k =[h x,m k ,h y,m k ,h z,m k ] T mεY k [Formula 13]
[0058] Next, a collection of the point groups of coordinate points near the marker is determined and set by a following procedure.
[0000] Ω={( k,m,r )| b ( f m k ,W r )=true, f m k =R C k h m k +t C k ,mεY k ,rεΞ,k εΦ}[Formula 14]
[0059] A point f m k is determined by the following expression. The point f m k is the three-dimensional point h m k of the depth image of the image k converted to a shared coordinate system (world coordinate system) between frames, using the approximate camera attitude determined as described above.
[0000] f m k =R C k h m k +t C k [Formula 15]
[0060] A function b(f m k , W r ) used to determine the collection of point groups returns “true” when f m k is near the marker. The function b(f m k , W r ) returns “false” when f m k is not near the marker.
[0061] FIG. 4 is a diagram for explaining an example of a judgment area for judging whether or not f m k is near the marker.
[0062] In the example shown in FIG. 3 , a rectangular parallelepiped area that is the rectangle W r of the marker r expanded by a (mm) in the normal direction of the marker plane and 13 (mm) in the direction opposite of the normal is the judgment area. The three-dimensional point h m k within the rectangular parallelepiped area is determined to be “true” and is extracted as a point configuring the marker area point group. The three-dimensional point h m k outside of the rectangular parallelepiped area is determined to be “false” and is not extracted as the point group.
[0063] [Perform High-Accuracy Calculation of Camera Attitude] (Step S 107 )
[0064] The cost function of the marker area point group is added to the above-described cost function E I , and a new cost function E F is defined.
[0000]
E
F
=
∑
(
k
,
h
,
i
,
j
)
∈
Ψ
(
ɛ
ij
kh
)
T
(
ɛ
ij
kh
)
+
η
∑
(
k
,
r
,
m
)
∈
Ω
(
δ
m
k
,
r
)
2
[
Formula
16
]
ɛ
ij
kh
=
[
ɛ
x
,
ij
kh
ɛ
y
,
ij
kh
ɛ
z
,
ij
kh
]
=
v
i
k
-
v
j
h
[
Formula
17
]
v
i
k
=
R
k
m
i
k
+
t
k
[
Formula
18
]
δ
m
k
,
r
=
-
n
r
T
(
R
k
h
m
k
+
t
k
)
-
d
r
[
Formula
19
]
[0065] The symbols n r T and d r in the functional expressions above indicate parameters of a plane to which the marker area point group belongs.
[0066] A camera attitude (R k , t k ) and plane parameters that minimizing the cost function E F are determined.
[0067] In other words, the sum of a second cost function obtained from the points extracted as the marker area point group and a first cost function E I , described above, are re-defined as the cost function E F . The camera attitude of when the image k is captured is estimated from the cost function E F .
[0068] Calculation for minimization of the cost function E F can be performed by the non-linear optimization method. For example, the Levenberg-Marquardt method can be used. During this calculation, robust estimation for preventing erroneous corresponding points is introduced. The robust estimation is, for example, M-estimator (robust estimation) or random sample consensus (RANSAC). However, because these methods are commonly used, descriptions thereof are omitted herein.
[0069] A cost function (second item) regarding the marker area point group is added to cost function E F . The cost function of the second item includes information from several tens of thousands of three-dimensional points included in the marker area point group.
[0070] As a result, the camera attitude (R k , t k ) obtained by calculation for minimization of the cost function E F has a significantly higher accuracy than the camera attitude (R c k , t c k ) obtained by the calculation for minimization of the cost function E I .
[0071] A coefficient n of a second item of the cost function E F is a positive value. The balance between the local features and the marker area point group is adjusted. When the marker area is disposed such as to be localized in the environment, estimation accuracy of the camera attitude may be decreased if the effect of the marker area is too strong. To equalize the effect of the local features and the effect of the point group of the marker area, the coefficient η is defined by a following expression.
[0000] η=3|Ψ|/|Ω| [Formula 20]
[0072] As described above, in the method for estimating a camera attitude of the present invention, first, based on the position of the marker that has been previously detected and the approximate camera attitude during imaging of the current frame, the approximate position of the marker in relation to the current frame is predicted. Points (marker neighboring points) near the predicted marker position are determined as a point group. A camera attitude (rotation matrix and translation matrix) that optimizes the evaluation function is determined, where the evaluation function conditions the distance between the marker neighboring point included in the point group and the estimation plane on which the marker is positioned. By this determination, the camera attitude can be re-estimated.
[0073] As a result of the above-described optimization of the evaluation function, the camera attitude that has been estimated in advance is corrected. Estimation of the camera attitude can be performed with high accuracy even in an environment in which occlusion occurs.
[0074] Estimation of the camera attitude such as this can be performed at high speed using a system that includes a camera and a computer. The camera captures images of an actual environment in which the planar marker is disposed. The computer performs processing of the images captured by the camera. The above-described steps can be processed by calculation by the computer.
INDUSTRIAL APPLICABILITY
[0075] The present invention can provide a method for enabling estimation of a camera attitude with high accuracy even in an environment in which occlusion occurs, and a system for performing the method.
|
In a method of estimating a camera attitude, based on the past-detected position of a marker and an appropriate camera attitude provided during current frame imaging, the position of the maker to the current frame is approximately predicted. Through extraction of points which are near the predicted marker position (marker neighboring points), a group of points are obtained. An attitude of the camera (rotation matrix and translation matrix) which optimizes an estimation function is obtained for re-estimating the camera attitude, where the estimation function needs, as its condition, a distance between the marker neighboring points included in the point groups and an estimation plane on which the marker is positioned. The point groups include many points extracted from the neighborhood of the marker, so that the preliminarily estimated approximate camera attitude can be corrected and estimated with higher accuracy even in an environment with occlusion.
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BACKGROUND OF THE INVENTION
The entire disclosure of Japanese Patent Application No. 2006-115482, filed Apr. 19, 2006 is expressly incorporated herein by reference.
1. Technical Field
The present invention relates to a printing apparatus. More specifically, the present invention relates to a method of detecting the amount of a printing material in a printing material storage container.
2. Related Art
Many ink jet printing apparatuses contain a printing material storage container which includes a sensor for detecting the amount of remaining printing material in the container. One example of a sensor is a piezoelectric element which has the ability to expand and contract upon application of a voltage. The piezoelectric element oscillates upon application of the voltage and outputs an output signal. Thus, the printing apparatus applies the voltage to the piezoelectric element and measures the oscillation frequency of the piezoelectric element contained in the output signal to determine whether or not a predetermined amount of printing material remains in the printing material storage container.
Typically, the frequency of the voltage applied to the piezoelectric element is adjusted to be a resonant frequency of the sensor and the printing material stored in the printing material storage container, so that the amplitude of the oscillation of the piezoelectric element is increased and oscillation frequency measurement is more accurate.
Often, however, the sensors contain manufacturing errors generated during the manufacturing process. Often, the amplitude of the oscillation of the piezoelectric element may be reduced according to the manufacturing errors of the sensors, while the drive signal which is used to drive the sensors are constant. This makes the measurement of the oscillation frequency of the piezoelectric element difficult to measure with a high degree of accuracy, that the output signals outputted from the sensors may differ even though the same amount of printing material remains in the printing material storage container. Consequently, there is currently a problem accurately measuring the amount of printing material stored in the printing material storage container.
BRIEF SUMMARY OF THE INVENTION
In order to solve at least part of the problems shown above, one aspect of the invention provides a printing apparatus configured to measure the amount of the printing material stored in the printing material storage container. Further, one advantage of the invention is a more accurate measurement of the amount of printing material stored in a printing material storage container.
The printing apparatus of the invention comprises an acquiring unit capable of acquiring frequency information from a memory, a drive signal generating unit capable of generating and outputting a drive signal which may be used for driving a piezoelectric element which has a first signal waveform at a first frequency and a second signal waveform at a second frequency which is different from the first frequency, a supply unit capable of selecting a waveform which increases the amplitude of oscillations of the piezoelectric element from the first signal waveform and the second signal waveform of the outputted drive signal based on frequency information and supplying a selected drive signal having the selected signal waveform to the piezoelectric element, a detecting unit capable of detecting a response signal which is outputted in association with the oscillation of the piezoelectric element after having stopped the supply of the selected drive signal, a measuring unit configured to measure the oscillation frequency of the piezoelectric element included in the response signal, and a determining unit configured to determine the amount of the printing material stored in the printing material storing container on the basis of the oscillation frequency.
One advantage of the present invention is that the residual oscillation of the piezoelectric element is excited effectively using only one drive signal. Therefore, since it is no longer necessary to generate a drive signal for each printing material storage container, the processing load and processing time of the printing apparatus is reduced. Furthermore, the present invention is capable of detecting the response signal more accurately, resulting in a more accurate measurement of the amount of the printing material in the storage container.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
FIG. 1 is an exemplary schematic configuration of a printing system.
FIG. 2 is an exemplary illustration of a main controller.
FIG. 3 is an explanatory drawing showing an electric configuration of a sub-controller and a cartridge according to the first example.
FIG. 4 is an explanatory drawing showing an example of a functional block of a switch controller according to the first example.
FIG. 5A is an explanatory front view showing a configuration of an ink cartridge according to the first example.
FIG. 5B is an explanatory side view showing the configuration of the ink cartridge according to the first example.
FIG. 6A is an explanatory pattern cross-sectional view of a peripheral portion of a sensor provided on the ink cartridge when ink remains according to the first example.
FIG. 6B is an explanatory pattern cross-sectional view of the peripheral portion of the sensor provided on the ink cartridge when ink does not remain according to the first example.
FIG. 7A is an explanatory drawing showing an error range of the characteristic frequency of the cartridge when ink remains according to the first example.
FIG. 7B is an explanatory drawing showing the error range of the characteristic frequency of the cartridge when ink does not remain according to the first example.
FIG. 8 is a waveform chart showing an example of a pulse waveform of a drive signal according to the first example.
FIG. 9 is an explanatory drawing showing an example of switch control data according to the first example.
FIG. 10 is a flowchart showing an ink amount determination process according to the first example.
FIG. 11 is a timing chart for explaining a frequency measurement process according to the first example.
FIG. 12 is a waveform chart showing an example of a pulse waveform of a drive signal according to a second example.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, the invention will be described using a series of examples listed below.
A. First Example
A1. System Configuration
FIG. 1 is a schematic configuration of an exemplary printing system. The printing system includes a printer 20 and a computer 90 . The printer 20 is connected to the computer 90 via a connector 80 .
The printer 20 includes a secondary scan feeding mechanism, a main scan feeding mechanism, a head control mechanism, and a main controller 40 for controlling the respective mechanisms. The secondary scan feeding mechanism includes a paper feed motor 22 and a platen 26 . The secondary scan feeding mechanism transports paper P by transmitting the rotation of the paper feed motor to the platen in the secondary scanning direction. The primary scan feeding mechanism includes a carriage motor 32 , a pulley 38 , a drive belt 36 tightly extended between the carriage motor 32 and the pulley 38 , and a sliding shaft 34 placed parallel to the platen shaft 26 . The sliding shaft 34 holds a carriage which is fixed to the drive belt 36 in a manner that allows the carriage to slide along the sliding shaft 34 . The rotation of the carriage motor 32 is transmitted to the carriage 30 via the drive belt 36 . The carriage 30 moves reciprocally along the axial direction (primary scanning direction) of the platen 26 via the sliding shaft 34 . The head control mechanism includes a printing head unit 60 mounted to the carriage 30 . The head control mechanism causes the printing head 69 to discharge ink on the paper P. The printer 20 further includes an operating unit 70 which allows the user to select various settings and confirm the status of the printer.
The printing head unit 60 includes a print head 69 and a cartridge mounting portion. The cartridge mounting portion accommodates six ink cartridges 100 a to 100 f . The printing head unit 60 further includes a sub-controller 50 .
The print head 69 includes a plurality of nozzles and a plurality of piezoelectric elements, and discharge ink drops from the respective nozzles according to the voltage applied to the respective piezoelectric elements to form dots on the paper P.
The ink cartridges 100 a to 100 f each are provided with a sensor which includes a piezoelectric element. The printer 20 supplies a drive signal to the piezoelectric elements of the sensors. The printer 20 determines the amount of ink stored in the ink cartridges by measuring the oscillation frequencies of the piezoelectric elements which is included in the response signals that are outputted from the piezoelectric elements, compared to the residual oscillations generated in the piezoelectric elements after the drive signal is stopped. Hereinafter, the ink cartridge is referred simply to as “cartridge.”
A2. Circuit Configuration of Printer
Referring now to FIGS. 2-4 , a circuit configuration of the printer 20 will be described. FIG. 2 is a drawing illustrating an exemplary electrical configuration of the main controller 40 . FIG. 3 is a drawing illustrating an exemplary electric configuration of the sub-controller 50 and a cartridge. FIG. 4 is a block diagram illustrating the switch controller.
The main controller 40 includes a CPU 41 , a memory 42 , an oscillator 43 configured to generate clock signals, an input and output unit (PIO) 44 configured to transmit signals between peripheral devices and transmit information to the sub-controller 50 , a drive signal generating circuit 46 , a drive buffer 47 , and an allotter 48 . These components are connected via buses 49 . The busses 49 are also connected to a connector 80 , and the main controller 40 is connected to the computer 90 via the busses 49 and the connector 80 . Within this configuration, the above-described components are capable of exchanging data.
The drive buffer 47 is used as a buffer for supplying dot ON and OFF signals to the print head 69 . The allotter 48 allots drive signals from the drive signal generating circuit 46 to the print head 69 at predetermined times.
The drive signal generating circuit 46 generates head drive signals PS, which are supplied to the print head 69 via the allotter 48 , along with drive signals DS which are supplied to the piezoelectric elements 112 via the sub-controller 50 . Hereinafter, the term “drive signal” is a “sensor drive signal.” The drive signal generating circuit 46 outputs the drive signal DS via the sub-controller 50 . The drive signal DS has a first signal waveform at a frequency F 1 and a second signal waveform at a frequency F 2 which is different from the frequency F 1 . In this example, the first signal waveform and the second signal waveform are generated so as to be arranged in series, and are outputted in sequence from the drive signal generating circuit 46 .
The CPU 41 acquires frequency information 135 (shown in FIG. 3 ) stored in the memory 42 from the sub-controller 50 .
The CPU 41 generates a first switch control data SD 1 for selecting either the first signal waveform SP 1 or the second signal waveform SP 2 , based on the acquired frequency information 135 , and supplies a drive signal having only the selected signal waveform to the piezoelectric elements. Hereinafter, the drive signal having only the selected signal waveform is referred to as the “selected drive signal.” The CPU 41 sends the generated first switch control data SD 1 to the sub-controller 50 . The first switch control data SD 1 is data for controlling a first switch SW 1 . The CPU 41 generates second switch control data SD 2 for controlling a second switch SW 2 and third switch control data SD 3 for controlling a third switch and sends the same to the sub-controller 50 . The switch control data SD will be described in detail later.
The sub-controller 50 is a circuit for executing a process relating to the cartridges 100 a to 100 f in cooperation with the main controller 40 . FIG. 3 the shows the portions of the circuit which are used during the ink measuring process. The sub-controller 50 is provided with a calculator 51 , the three switches SW 1 to SW 3 , and an amplifier 52 .
The calculator 51 includes a CPU 511 , a memory 513 , an interface (“I/F”) 514 , an I/O portion (“SIO”) 515 for transmitting signals between the components in the sub-controller 50 and the cartridges 100 a to 100 f , and a switch controller 516 . The respective components of the main controller 40 are connected via basses 519 . The calculator 51 receives signals from the main controller 40 via the interface 514 . The calculator 51 controls the three switches SW 1 to SW 3 via the switch controller 516 . The calculator 51 transmits output from the amplifier 52 via the SIO 515 .
The switch controller 516 controls the first switch SW 1 to the third switch SW 3 according to the switch control data SD. The detailed functional blocks of the switch controller 516 will be described in reference to FIG. 4 .
As shown in FIG. 4 , the switch controller 516 includes a controller 210 , and switch control signal output circuits 220 a , 220 b and 220 c which are configured for each switch. The switch control signal output circuit 220 a is connected to the first switch SW 1 and controls the connecting state of the first switch SW 1 . The switch control signal output circuit 220 b is connected to the second switch SW 2 and controls the connecting state of the second switch SW 2 . The switch control signal output circuit 220 c is connected to the third switch SW 3 and controls the connecting state of the third switch SW 3 . Each of the switch control signal output circuits 220 a to 220 c include a shift register 200 , a latch circuit 201 , and a data decoder 202 .
Clock signals CLK, latch signals LAT, change signals CH, and switch control data SD are each supplied from the CPU 41 to the switch controller 516 . The switch control data SD is transferred to the shift register 200 synchronously with the clock signals CLK from the oscillator 43 of the main controller 40 . The transferred switch control data SD is latched once by the latch circuit 201 . The latched switch control data SD is entered to the data decoder 202 .
The controller 210 receives input of the latch signals LAT and the change signals CH. The controller 210 generates the switch control signal CS for ON and OFF, controlling the switch on the basis of the latch signals LAT and the change signal CH. The switch control signal CS which is generated by the controller 210 is supplied to the data decoder 202 . The data decoder 202 outputs the switch control signal CS to the switch on the basis of the latched switch control data SD. The switch control signal CS will be described in greater detail below.
The first switch SW 1 is a one-channel analog switch. One of the terminals of the first switch SW 1 is connected to the drive signal generating circuit 46 of the main controller 40 , and the other terminal is connected to the second switch SW 2 and the third switch SW 3 . The first switch SW 1 is set to the connected state while a selected drive signal SDS is supplied, and is set to the disconnected state when detecting a response signal RS from the sensor 110 .
The second switch SW 2 is a 6-channel analog switch. One of the terminals on one side of the second switch SW 2 is connected to the first switch SW 1 and the third switch SW 3 , and the six terminals on the other side are each connected to the electrodes of the sensors 110 of the six cartridges 100 a to 100 f . The other electrode of each sensor 110 is grounded. The six cartridges 100 a to 100 f are selected in sequence by switching the second switch SW 2 in sequence.
The third switch SW 3 is a one-channel analog switch. One of the terminals of the third switch SW 3 is connected to the first switch SW 1 and the second switch SW 2 , and the other terminal is connected to the amplifier 52 . The third switch SW 3 is set to the disconnected state when supplying the drive signal DS to the sensor 110 , and is set to the connected state by receiving a supply of the ON signals from the switch controller 516 when detecting the response signal RS from the sensor 110 .
The amplifier 52 includes an OP amplifier, and functions as a comparator for comparing the response signal RS and a reference voltage Vref, and outputs high signals when the voltage of the response signal RS is the reference voltage Vref or higher and outputs low signals when the voltage of the response signal RS is lower than the reference voltage Vref. Therefore, output signals QC from the amplifier 52 are digital signals including only the high signals and the low signals.
The CPU 41 counts the output signals QC outputted from the amplifier 52 , measures the oscillation frequencies of the piezoelectric elements 112 , and determines the amount of ink stored in the ink cartridges based on the oscillation frequencies. Accordingly, the CPU 41 displays the result of on a display of the computer 90 , so that the user is notified of the ink amount.
A3. Detailed Configuration of Ink Cartridge and Sensor
FIGS. 5A-B and FIGS. 6A-B illustrate a detailed configuration of the ink cartridge and the sensor. FIGS. 5A and 5B are a front view and side view of the ink cartridge. FIGS. 6A and 6B are cross-sectional views of a peripheral portion of the sensor located on the ink cartridge.
As shown in FIG. 5A and FIG. 5B , a casing 102 of the cartridge 100 a includes a plurality of storage chambers for storing ink. A main storage chamber MRM occupies a major portion of a capacity of the entire storage chamber. A first sub-storage chamber SRM 1 is in communication with an ink supply port 104 , which is located on its bottom surface. A second sub-storage chamber SRM 2 is also in communication with the main storage chamber MRM, and is located near the main storage chamber MRM's bottom surface.
FIGS. 6A and 6B are cross-sectional views of a portion of the sensor taken along the line A-A in FIG. 5B , as viewed from above. As shown in FIGS. 6A and 6B , the sensor 110 includes a piezoelectric element 112 and a sensor attachment 113 . The piezoelectric element 112 includes a piezoelectric unit 114 and two electrodes 115 , 116 on either side of the piezoelectric unit 114 , and is installed to the sensor attachment 113 . The piezoelectric unit 114 is a ferroelectric substance, and is formed of, for example, PZT (Pb(ZrxTi1-x)O3). Within the sensor attachment 113 a substantially angular C-shaped bridge flow channel BR is formed. A portion of the sensor attachment 113 between the bridge flow channel BR and the piezoelectric element 112 is comprised of a thin film. In this arrangement, a peripheral portion of the piezoelectric element 112 including the bridge flow channel BR oscillates with the piezoelectric element 112 .
The ink stored in the cartridge 100 a flows as indicated by a solid arrow in FIGS. 5A , 5 B, 6 A, and 6 B. More specifically, the ink stored in the main storage chamber MRM flows from the bottom surface area into the second sub-storage chamber SRM 2 . The ink flowing into the second sub-storage chamber SRM 2 flows from a first side hole 76 , to the bridge flow channel BR of the sensor attachment 113 , through a second side hole 75 , and into the first sub-storage chamber SRM 1 . The ink flowed into the first sub-storage chamber SRM 1 passes through the ink supply port 104 and is supplied to the print head unit 60 .
FIG. 6A shows the state wherein a predetermined amount of ink remains in the cartridge 100 a (hereinafter referred to as “remaining ink”). As shown in FIG. 6A , the term “remaining ink” represents the state wherein the ink is in the bridge flow channel BR. That is, the term “remaining ink” represents a state wherein ink exists at a position of the cartridge 100 a where the sensor 110 is installed (ink detecting position), and the ink is in contact with a portion of the thin film sandwiched between the bridge flow channel BR and the piezoelectric element 112 (ink detecting area) of the sensor attachment 113 .
In contrast, FIG. 6B shows the state wherein the ink is less than the predetermined amount (hereinafter referred to as “no remaining ink”). The term “no remaining ink” represents the state wherein the ink is not in the bridge flow channel BR. That is, the term “no remaining ink” represents a state wherein the ink does not exist at the ink detecting position, and the ink is not in contact with the ink detecting area.
A4. Drive Signal
The drive signal with improved detection accuracy of the oscillation frequencies will now be described. As described above, the printer 20 determines the amounts of the ink stored in the cartridges by supplying the drive signal to the piezoelectric elements provided on the cartridges and measuring the frequencies of the response signals outputted from the piezoelectric elements. Therefore, it is desirable to increase the amplitude of the response signals in order to improve the detection accuracy of the oscillation frequencies. Further, it is preferable to adjust the frequency of the drive signal to be equal to characteristic frequencies of the piezoelectric elements 112 in order to improve the detection accuracy of the oscillation frequencies of the response signals. The piezoelectric elements resonate and output response signals with large amplitudes by supplying a drive signal having the same frequency as the characteristic frequencies of the piezoelectric elements to the piezoelectric elements.
However, difficulties arise as the cartridge sensor is subject to the manufacturing errors within the manufacturing process. Therefore, in general, the characteristic frequency fF when ink remains and the characteristic frequency fE when ink does not remain have margins of error with respect to a target characteristic frequencies H 1 and H 2 , respectively. This margin of error will be described using FIGS. 7A and 7B . FIGS. 7A and 7 B are drawings showing an exemplary error range of the characteristic frequency of the cartridge. FIG. 7A shows an error range of the characteristic frequency of the piezoelectric element when there is remaining ink in the container, and FIG. 7B shows an error range of the characteristic frequency of the piezoelectric element when there is no ink remaining in the container.
As shown in FIG. 7A , when there is ink remaining in the container, there is an error range ER 1 from HFmin (KHz) to HFmax (KHz). On the other hand, as shown in FIG. 7B , when there is no remaining ink, there is an error range ER 2 from HEmin (KHz) to HEmax (KHz). As shown in the figures, there is a smaller range of oscillations included in the error range ER 2 than in the error range ER 1 .
The method of generating the response signal when ink does not remain will be described. When the frequency of the drive signal is set to the same frequency as the intermediate frequency Hm of the error range ER 1 and is supplied to the piezoelectric element, the characteristic frequency fE of the piezoelectric element of the cartridge is included within the accuracy range of Equation 1 shown below. Hereinafter, the range expressed by the Equation 1 is referred to as a detectable range DR.
(drive signal frequency F *3)α%≦characteristic frequency fE ≦(drive signal frequency F* 3)+α% Equation 1:
In Equation 1, the value a is an allowable limit of error calculated on the basis of the manufacturing test in the manufacturing process, and is α=8 in this example. When the characteristic frequency fE of the cartridge to be processed is included in the detectable range DR (DRmin (KHz) to DRmax (KHz)), the residual oscillation of the piezoelectric element is effectively excited and hence the amplitude of the response signal may be amplified. However, in situations, such as those shown in FIG. 7 , when the characteristic frequency fE of the cartridge to be processed is higher than DRmax (KHz) (the hatched range in FIG. 7B ) the residual oscillation of the piezoelectric element is not effectively excited, and the detection accuracy of the response signal is lowered.
In order to adjust the frequency of the drive signal to be the same as the characteristic frequency of the piezoelectric element of the cartridge, it is necessary to generate different drive signals every time the ink amount determination process is performed, requiring significant process time.
In order to solve this problem, the printer according to the invention generates and outputs a drive signal including two types of signal waveforms, SP 1 and SP 2 , each having different frequencies. The printer controls the connecting state of the first switch SW 1 , selects the signal waveform having a frequency closer to the characteristic frequency of the piezoelectric element from between SP 1 and SP 2 , and supplies a drive signal associated with the selected signal waveform to the piezoelectric element. Accordingly, it is not necessary to generate drive signals with differing frequencies for each cartridge to be processed, meaning that a drive signal capable of effectively exciting the residual oscillations of the piezoelectric elements is supplied.
In this example, a waveform of a given frequency F 1 , which is included in the error range ER 1 and is a frequency higher than the intermediate frequency Hm of the error range ER 1 is determined to be the first signal waveform SPA, and the waveform of a given frequency F 2 , which is included in the error range ER 1 and is a frequency lower than the intermediate frequency Hm of the error range ER 1 is determined to be the second signal waveform SP 2 .
Referring now to FIG. 8 , the drive signal DS generated by the drive signal generating circuit 46 will be described. FIG. 8 is a waveform chart showing an outputted drive signal and the selected drive signal SDS to be applied to the piezoelectric elements.
The CPU 41 issues instructions in order to generate the drive signal to the drive signal generating circuit 46 using a drive signal generating parameter stored in the memory 42 . The drive signal generating circuit 46 generates the drive signal DS according to the instructions in order to generate a drive signal, which is then issued from the CPU 41 . The drive signal generating parameter includes various parameters required for generating drive signal such as a drive voltage Vh, a maximum voltage VH, a minimum voltage VL, a ratio for defining the relation between the drive voltage Vh and the reference voltage Vref, the frequency F 1 , and the frequency F 2 .
The drive signal DS includes the first signal waveform SP 1 generated during a term Ta and the second signal waveform SP 2 generated during a term Tb of a drive signal cycle T. The term Ta is one cycle of the first signal waveform SP 1 and follows the equation Ta=1/F 1 . The term Tb is one cycle of the second signal waveform SP 2 and follows the equation Tb=1/F 2 . The drive signal cycle T (term Ta+term Tb) corresponds to one cycle T of the drive signal DS.
The method of selecting the drive signal waveform of the selected drive signal to be supplied to the piezoelectric element from the first signal waveform SP 1 and the second signal waveform SP 2 will now be described. The drive signal selecting process is executed by the CPU 41 . The characteristic frequency fF is calculated from the error range ER 1 , the error range ER 2 , and the characteristic frequency fE, using Equation 2 shown below. The characteristic frequency fE when there is no remaining ink is obtained through a test measurement during the manufacturing process.
fF =( fE−HE min)*( HF max− HF min)/( HE max− HE min)+ HF min Equation 2:
The memory 130 includes the characteristic frequency fE of the piezoelectric element when there is no remaining ink, which is stored in advance as frequency information 135 . The CPU 41 acquires the characteristic frequency fE from the memory 130 of the cartridge to be processed via the sub-controller 50 , and calculates the characteristic frequency fF using Equation 2. When the calculated characteristic frequency fF is higher than the intermediate frequency Hm, the CPU 41 selects the first signal waveform SP 1 as a waveform of the selected drive signal, and when the calculated characteristic frequency fF is lower than the intermediate frequency Hm, the CPU 41 selects the second signal waveform SP 2 as a waveform of the selected drive signal.
When the selected drive signal comprising the first signal waveform SP 1 is supplied to the piezoelectric element, the detectable range DR is calculated using Equation 1. When the characteristic frequency fE of the piezoelectric element of the cartridge when there is no remaining ink is included in the detectable range DR of Equation 1, the residual oscillation of the piezoelectric element is effective. When the characteristic frequency fF when there is ink remaining in the cartridge, is included within the range of “drive signal frequency F±25%”, the residual oscillation of the piezoelectric element is effectively excited.
A5. Switch Control Data
The CPU 41 generates the first switch control data SD 1 on using the selection process shown above. Referring now to FIG. 9 , the first switch control data SD 1 will be described. FIG. 9 is an explanatory illustration showing the selection patterns of the selected drive signal and the first switch control data SD 1 . The selection table 500 shown in FIG. 9 shows selected patterns of the signal waveform together with an association function between the first switch control data SD 1 and the characteristic frequency fF. For example, the CPU 41 selects (shown as “0”) the first signal waveform SP 1 as the waveform of the selected drive signal in the case where the characteristic frequency fF>intermediate frequency Hm. In this case, as shown in FIG. 9 , since the first switch control data SD 1 is [10], the CPU 41 generates the first switch control data SD 1 [10]. On the other hand, when the characteristic frequency fF≦intermediate frequency Hm, the second signal waveform SP 2 is selected as the waveform of the selected drive signal. In this case, since the first switch control data SD 1 is [01], the CPU 41 generates the first switch control data SD 1 [01] and sends the same to the calculator 51 .
A6. Switch Control Signal
The calculator 51 outputs the first switch control signal CS, which controls the connecting state of the first switch SW 1 according to the first switch control data SD 1 sent from the CPU 41 . The waveforms of the switch control signals and the selected drive signals to be applied to the piezoelectric elements will be described in reference to FIG. 8 . The selected drive signals shown in FIG. 8 indicate the drive signals to be applied to the piezoelectric elements.
The switch controller 516 outputs the switch control signal CS for controlling ON and OFF of the first switch SW 1 on the basis of the latch signal LAT, the change signal CH, and the first switch control data SD 1 supplied from the CPU 41 . When the switch control signal CS is at a high level, the first switch SW 1 is in the connected state. Therefore, as shown in FIG. 8 , when the first switch control data SD 1 is [10], the switch controller 516 outputs high-level signals (ON signals) over the term Ta, and the first switch SW 1 is in the connected state. In contrast, when the switch controller 516 outputs low-level signals over the term Tb, the first switch SW 1 is in the disconnected state. Therefore, as shown in the selected drive signal SDS 1 in FIG. 8 , only the signals having the first signal waveform SP 1 are supplied to the piezoelectric elements 112 . When the first switch control data SD 1 is [01], since the switch controller 516 outputs low-level signals over the term Ta, the switch is in the disconnected state, and the switch controller 516 outputs high-level signals over the term Tb, and the switch is in the connected state. Therefore, as shown in the selected drive signal SDS 2 in FIG. 8 , only the signals having the second signal waveform SP 2 are supplied to the piezoelectric elements 112 . Accordingly, a drive signal DS which excites the piezoelectric elements 112 effectively is selected from the two signal waveforms SP 1 and SP 2 .
A7. Ink Amount Determination Process:
Referring now to FIGS. 10 and 11 , the ink amount determination process that the main controller 40 and the sub-controller 50 of the printer 20 execute in cooperation will be described. FIG. 10 is a flowchart explaining the ink amount determination process. FIG. 11 is a timing chart for explaining a frequency measuring process.
The process of determining the ink amount is a process for determining whether the ink amount stored in the cartridge is more or less than a predetermined amount for each cartridge. The process of determining the ink amount is typically executed when the power of the printer 20 is turned ON.
The CPU 41 of the main controller 40 selects a cartridge as a target of the process of determining the ink amount from among the six cartridges 100 a to 100 f when the process is started (Step S 101 ).
The main controller 40 acquires the frequency information 135 relating to the characteristic frequency of the piezoelectric element 112 from the memory 130 provided on the target cartridge (Step S 102 ). More specifically, the main controller 40 sends a command for causing the sub-controller 50 to acquire the frequency information 135 stored in the memory 130 of the cartridge, in order to send the information to the calculator 51 of the sub-controller 50 . The CPU 511 of the calculator 51 acquires the frequency information 135 and sends the acquired frequency information 135 to the sub-controller 50 .
The main controller 40 generates the switch control data for determining the first switch control data SD 1 on the basis of the acquired frequency information 135 (Step S 103 ), using the process described above. In this example, the second signal waveform SP 2 is selected, and the first switch control data SD 1 [01] is generated.
The main controller 40 generates the drive signal DS having the first signal waveform SP 1 and the second signal waveform SP 2 and outputs the same to the piezoelectric element in order to execute the frequency measuring process (Step S 105 ). Referring now to a timing chart shown in FIG. 11 , the frequency measuring process will be described. The clock signal CLK, a measurement command CM, the latch signal LAT, and the change signal CH shown in FIG. 11 are signals that may be sent to the calculator 51 of the sub-controller 50 from the main controller 40 in the frequency measuring process. The switch control signal CS is a signal outputted from the switch controller 516 . The measurement command CM includes information for specifying the cartridge to be processed together with a command that instructs execution of the frequency measurement process. The drive signal DS is a signal outputted from the drive signal generating circuit 46 of the main controller 40 as described above. The response signal RS is a signal generated in association with the residual oscillation of the piezoelectric element after having supplied the drive signal DS.
The calculator 51 of the sub-controller 50 controls the second switch SW 2 according to the measurement command CM which the calculator 51 has received in advance to the timing when the latch pulse P 1 of the latch signal was received, and brings the piezoelectric element 112 of the cartridge to be processed into the state of being connected with the sub-controller 50 . Furthermore, the calculator 51 controls the connecting state of the first switch SW 1 on the basis of the first data of the first switch control data SD 1 at the time when the latch pulse P 2 is received. In this example, the first switch control data SD 1 [01] is supplied to the switch controller 516 . Since the first data of the first switch control data SD 1 is [0], the ON signal is not outputted to the first switch SW 1 from the switch controller 516 , and hence the first switch SW 1 is in the disconnected state. Furthermore, The calculator 51 brings the third switch SW 3 into the disconnected state at a timing when the latch pulse P 1 is received. Accordingly, the amplifier 52 is electrically disconnected from the drive signal generating circuit 46 and the piezoelectric element 112 , and hence the drive signal DS is not applied to the amplifier 52 .
The main controller 40 generates a change pulse P 2 of the change signal at a timing when the term Ta terminates. The calculator 51 controls the connected state of the first switch SW 1 based on the second data of the first switch control data SD 1 at the time when the change pulse P 2 is received. In this example, since the second data of the first switch control data SD 1 is [1], the ON signal is outputted from the switch controller 516 to the first switch SW 1 . The first switch SW 1 is set to the connected state upon reception of the ON signal. Accordingly, only the selected drive signal having the second signal waveform SP 2 is applied to the piezoelectric element 112 .
The main controller 40 generates a change pulse P 3 at the time when the application of the drive signal is terminated. The calculator 51 of the sub-controller 50 brings the first switch SW 1 into the disconnected state at the time when the change pulse P 3 is received. A term from the latch pulse P 1 to the change pulse P 3 is referred to as the drive voltage application term T 1 .
After having terminated the drive voltage application term T 1 , the piezoelectric element 112 is oscillated by the drive signal. The piezoelectric element 112 outputs a response signal RS according to distortion in association with the oscillation. After having generated the change pulse P 3 , the main controller 40 generates a change pulse P 4 . The calculator 51 of the sub-controller 50 brings the third switch SW 3 into the connected state at upon reception of the change pulse P 4 . Consequently, the response signal RS from the piezoelectric element 112 is supplied to the amplifier 52 .
The amplifier 52 functions as a comparator as described above, and outputs the output signal QC as a digital signal according to the waveform of the response signal RS to the calculator 51 . The calculator 51 calculates an oscillation frequency H of the response signal RS on the basis of the acquired output signal QC and sends the signal RS to the main controller 40 .
The main controller 40 determines the amount of ink in the cartridge based on the oscillation frequency H (Step S 105 ). Next, the main controller 40 determines if the amount of ink in the cartridge to be more than the predetermined amount when the oscillation frequency H is compared to the above-described characteristic frequency H 1 (Step S 106 ). Similarly, the main controller 40 determines if the amount of ink in the cartridge is smaller than the predetermined amount when the oscillation frequency H is compared to the characteristic frequency H 2 (Step S 107 ).
The main controller 40 sends the result of determination of the ink amount to the computer 90 . Accordingly, the computer 90 may notify the result of determination of the received ink amount to the user.
In the printing system of this invention, the drive signal has a plurality of signal waveforms with different frequencies. The plurality of signal waveforms are outputted and one is selected to form a drive signal according to the characteristic frequency of each ink cartridge, so that a selected drive signal includes only the selected signal waveform is supplied to the piezoelectric element. Therefore, in the ink amount determination process, it is no longer necessary to regenerate the drive signal for each cartridge, alleviating the processing load of the printing apparatus, and reducing the processing time of the process.
Since it is not necessary to configure a circuit individually for each signal waveform in order to generate the plurality of signal waveforms, the circuit required to execute the process of determining the amount of ink is simplified.
In accordance with one embodiment of the invention, the drive signal which is used to oscillate the piezoelectric element is selected from a first signal waveform SP 1 and a second signal waveform SP 2 , there is improved accuracy in detecting the response signal, and the accuracy of the ink amount determination is improved.
B. Second Example
In the example described above, one shot (one cycle) each of the first signal waveform SP 1 and the second signal waveform SP 2 are included in one cycle of the drive signal DS. In the second example, for example, two shots (two cycles) each of the signal waveforms may be included.
B1. Waveform of Drive Signal
FIG. 12 is a waveform chart showing a drive signal DS′ according to the second example. The drive signal DS′ is a signal outputted from the drive signal generating circuit 46 . Within the drive signal generating circuit 46 , a first signal waveform SP 1 ′ and a second signal waveform SP 2 ′ containing the waveforms for two cycles respectively are included in the drive signal cycle T of the drive signal DS′ as shown in FIG. 12 . The term Ta indicates one cycle T of the signal at the frequency F 1 , and the term Tb indicates one cycle of the signal at the frequency F 2 .
In this example, when the first signal waveform SP 1 is selected as a waveform of the selected drive signal, only the first signal waveform SP 1 ′ including the waveforms for two cycles is supplied to the piezoelectric element, and the second signal waveform SP 2 ′ is not supplied to the piezoelectric element.
The piezoelectric element is excited in order to create a residual oscillation with a large amplitude in association with the increase in number of cycles (number of shots) of the waveform, resulting in improved detection accuracy of the response signal. However, this example results in increased processing time, in association with increase in number of shots of the waveform to be supplied to the piezoelectric element. Therefore, the waveform of the selected drive signal is preferably two shots or smaller. Accordingly, the amplitude of the oscillation of the piezoelectric element 112 is increased, the detection accuracy of the response signal is further improved, and the processing time is reduced.
As shown in FIG. 12 , the numbers of shots included in the first signal waveform SP 1 ′ and the second signal waveform SP 2 ′ are preferably the same. This allows response signals of the same level to be detected at a high degree of accuracy irrespective of which one of the first signal waveform SP 1 ′ and the second signal waveform SP 2 ′ is supplied to the piezoelectric element.
C. Modification
In the examples described above, the drive signal having the waveforms at the two different frequencies are generated from within the error range ER 1 of the characteristic frequency when ink remains in the cartridge. However, it is also possible to generate the drive signal having a waveform of the drive signal for executing the ink amount determination process both when there is ink remaining in the cartridge and when there is no ink remaining in the cartridge. In this configuration, it is not necessary to regenerate the drive signal during the ink amount determination processes when ink remains in the cartridge and when ink does not remain in the cartridge, and hence the processing time may be preferably reduced. Since it is not necessary to configure the circuit for generating the drive signal to be used when executing the each of the processes for determining the ink amount, the circuit size may be reduced.
Although various examples of the invention have been described thus far, the invention is not limited to the examples shown above and, needless to say, various configurations may be employed without departing the scope of the invention.
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A printing apparatus to which a printing material container is detachably mounted, the printing material container having a piezoelectric element for detecting the amount of material stored in the container and a memory unit storing the natural vibration frequency of the piezoelectric element, the printing apparatus comprising means for acquiring the frequency information from the memory unit, means for generating a drive having a first signal waveform at a first frequency and a second signal waveform at a second frequency different from the first frequency, means for selectively supplying either the first or second signal waveform to the piezoelectric element so as to increase the amplitude of the vibrations of the piezoelectric element; means for detecting a response signal, means for measuring the vibration frequency contained in the response signal, and means for determining the amount of material stored in the printing material container based on the measured vibration frequency.
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BACKGROUND OF THE INVENTION
The invention relates to a moving-bed reactor for the treatment of fluids, in particular of flue gases from power station installations or the like, in accordance with the preamble of claim 1.
As indicated in DE 3,732,567 Al, moving-bed reactors are used for the treatment of fluids, for example flue gases, over more or less fine-grained loose materials. The loose material forms a loose-material bed moving downwards through the reactor and is fed into the reactor at the top and discharged at the bottom continuously, quasi-continuously or batchwise. In the region of the loose-material discharge from the treatment zone, a so-called inflow tray is provided which has outlet openings for the loose material on the one hand and inlet openings for the fluid to be treated on the other hand. It is essential here that the fluid to be treated is distributed as uniformly as possible in the entire moving-bed reactor, so that the moving loose material as a whole acts as an absorbtion filter, i.e. the pollutants are bound to the surface of the loose material. The technology of these absorption filter installations is adequately known and described, for example, also in WO 87/00768 with further literature references, for example German patent specification 3,228,984. The problem in moving-bed reactors of this type is, inter alia, to obtain the most uniform distribution possible of the gas to be treated within the downward-moving loose material, an optimization of the required loose-material rate being necessary. In the cited state of the art, the flow of the loose-material layer through the gas to be treated takes place in the so-called countercurrent process, i.e. the gas moving upwards flows in countercurrent through the loose material moving down in the reactor.
Furthermore, there are so-called crossflow installations, in which the loose material flowing downwards in a cylindrical or prismatic housing is penetrated transversely by the flue gas which is to be treated. In this case, the gas is fed along the entire loose-material height to the cylindrical housing by means of louvre-type slots in the housing wall. Admittedly, the crossflow installations have the advantage that in general no additional inflow trays are required in the interior of the reactor, as is the case in the abovementioned printed publications. In fact, such inflow trays serving to produce uniform distribution of the gas within the reactor have the disadvantage that the uniform downward flow of the loose material can be adversely affected. In order to ensure that all the loose material present in the reactor can participate in the reaction, it is absolutely necessary that so-called mass flux takes place throughout the reactor. For a definition of mass flux, attention is brought to the following literature reference: A. W. Jenike, Storage and Flow of Solids, Bulletin 123 of the UTAH Engineering Experiment Station University of UTAH, USA. In contrast thereto, in the case of so-called core flow, the loose material would flow off only through a flow tube surrounded by dead zones. Since, however, no solids exchange takes place in the dead zones, reaction with a gas seeping past also no longer takes place after a short time.
The known crossflow process has, however, the the disadvantage that, due to the necessary mass flux, very steep and correspondingly high outlet funnels are required, without lateral flow through the contents thereof, which therefore remain uninvolved in the reaction. A further disadvantage of the crossflow process is that two opposite cylinder walls of the reactor must be gas-permeable. At the same time, a trickling-out or blowing-out of solid must be avoided, especially on the cylinder wall located downstream. This is only insufficiently the case in the known design of the gas-permeable walls in the form of louvre-type slots or mutually overlapping plates. If screens are used in place of the plates, these also tend to block very easily. Therefore, in order to obtain an adequate gas permeability of the loose bed in the crossflow process, the use of crossflow reactors is restricted to relatively coarse loose materials having a grain size of more than 2 mm. Moreover, with continuous attrition, the not entirely avoidable dusty fines must be removed before the loose material is used again, since the dust blocks the flow channels located between the larger particles and hence causes a steady rise of the flow resistance. Crossflow reactors are therefore substantially more sensitive to attrition, which is therefore removed during regeneration and thus causes considerable costs.
The further disadvantage of the crossflow process is that the residence time of the gas is shorter than would be the case in a vessel with longitudinal flow. Both the countercurrent reactor and the crossflow reactor of the state of the art accordingly show considerable disadvantages.
If, in WO 87/00768 mentioned at the outset, a loose-material vessel is used which does not have a tapering outlet funnel in its bottom region, a mass flux is also impossible with this vessel because of the numerous internals as inflow trays, i.e. a core flow is established which leads to non-uniform flow of loose material through the vessel.
The same would apply to the cited DE 3,732,567, although this contains funnel-shaped loose-material outlets. In this loose-material outlet, however, extensive internals are inserted in the form of inflow trays, which prevent uniform flow throughout the vessel, i.e. mass flux.
SUMMARY OF THE INVENTION
By contrast, the moving-bed reactor according to the invention has the advantage that, owing to a special design of the funnel-shaped outlet of the loose-material vessel, mass flux is established within the reactor, i.e. the loose material drops downwards fully uniformly across the entire cross-section and does not form any separate flow tubes with dead zones surrounding the latter. Moreover, due to the design according to the invention of the funnel-shaped outlet, very uniform flow-through of the loose material, all of which flows down uniformly, is achieved. The gas to be introduced into the reactor is distributed via the outlet funnel of louvre-type structure with mutually overlapping plates almost across the entire cross-section, i.e. across the entire vessel cross-section of the reactor except for the size of the lowest outlet cross-section. In particular, no internal structures whatsoever for producing an inflow tray for uniform charging of the loose material with gas to be treated are therefore necessary. However, it is precisely this which creates the prerequisite for always establishing, within the vessel, a mass flux which only makes it possible for gas to flow uniformly through the loose material in its entire cross-section and its entire height. Only in this way is optimum effectiveness of the countercurrent process achieved. The invention here starts from the fundamental idea that uniform charging of the vessel interior across the entire cross-section, if possible, must take place without inflow trays arranged in the interior of the vessel. This is achieved by a mass flux outlet funnel, of louvre-type structure, of the loose-material vessel, the lateral, mutually overlapping, plate-like slots of the funnel serving as gas feed openings over a wide cross-sectional region of the vessel. Admittedly, WO 87/00768 also uses a plurality of inflow trays which have a roof-like structure and which are built up in louvre fashion or plate fashion. However, these roof-shaped internals are placed inside the vessel and very decisively affect the flow path of the downward-flowing loose material, so that only core flow can result here.
Advantageous further developments and improvements of the moving-bed reactor indicated in the main claim are possible as a result of the measures listed in the subclaims.
Of particular advantage is the arrangement of the louvre-type inlet openings at the outlet funnel of the vessel in such a way that different inflow resistances are generated due to different flow passage cross-sections. As a result, a uniform gas distribution over the entire funnel height can be achieved in this vessel region, depending on the gas inlet. This vessel region surrounding the louvre-type outlet funnel for the loose material can be formed by a further funnel-shaped vessel region or by a cylindrical vessel region.
Especially for the treatment of flue gases from power station installations, a particular interconnection of the moving-bed reactors is possible according to an advantageous further development of the invention. In this case, additional inflow trays, which serve as inlet openings for additional treatment gases, can be present inside one or more reactors.
Expediently, such moving-bed reactors are arranged in superposition, since the loose material can move by gravity from one reactor to another in series connection. If these reactors are each to be charged with flue gas in parallel connection, this can likewise be effected by superposed reactors, where the loose material flows only once through the entire cross-section of each reactor and is otherwise taken through single pipes within or outside the particular reactor.
BRIEF DESCRIPTION OF THE DRAWINGS
Advantageous and expedient illustrative examples of the invention are represented in the drawing and explained in more detail in the following description, with an indication of further features essential to the invention, and advantages. In the drawing:
FIG. 1 shows a single moving-bed reactor with loose material flowing down and rising flue gas,
FIG. 2 shows a reactor according to FIG. 1 with a further inflow tray additionally provided inside the reactor,
FIG. 3a and 3b each show two superposed moving-bed reactors in series arrangement,
FIG. 4 shows two superposed moving-bed reactors in parallel arrangement and
FIG. 5 shows a plurality of superposed moving-bed reactors operated in parallel.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a first illustrative example of a moving-bed reactor 1 for thetreatment of fluids 2, in particular of flue gases 2 from power station installations, by means of a loose, i.e., particulate material 3. The loose material 3 consists, for example, of activated coke having a grain size of, for example, 2 mm. An adsorption of the pollutants in the flue gas takes place on this activated coke. This step is very extensively described in the relevant literature.
The moving-bed reactor 1 consists of a cylindrical or prismatic vessel 4 which is charged by means of an upper, central charging opening 5 with loose material 3, in general continuously (arrow 6).
The loose material 3 moves downwards in the vessel 4, while the flue gas 2 fed in the lower region of the vessel 4 flows upwards, so that a countercurrent results.
In its lower region, the vessel 4 has a downward-tapering funnel 7 which guides the loose material 3 to a bottom loose-material outlet 8. The loosematerial discharged from the vessel 4 (arrow 9) can, for example, be placedupon a conveyor belt (loose material 3') and discharged for further processing (arrow 11).
In FIG. 1, a feed pipe 12 for the flue gas 2 is shown in the lower region of the vessel 4 and a discharge pipe 13 for the treated and purified flue gas 2'' is shown in the upper region.
The moving-bed reactor 1 shown in FIG. 1 has an overall height of h 1 , a total loose-material height of h 2 and an effective funnel height ofh 3 . From this, the remaining loose-material height results as h 4 =h 2 -h 3 in the vessel 4 which has a diameter D. The aperture angle α of the funnel 7 is determined, as a function of the flow properties of the loose material, in such a way that mass flux is established everywhere in the moving-bed reactor, i.e. both in the upper part of the vessel 4 and in the funnel region 7, i.e. the loose material moves uniformly downwards in every cross-sectional region and does not form any individual flow tubes with surrounding dead zones.
According to the invention, the downward-tapering funnel 7 is now designed in louvre fashion with mutually overlapping, plate-shaped wall sections 14, whose surface centres 15 each lie on a common connecting line 16. The connecting lines 16 form the angle legs of the angle α. The individual wall sections 14 have a length s, these wall sections overlapping by about 1/3 to half their length s. The spacing between each two overlapping wall sections 14 is marked "t". This spacing forms the effective cross-section for the flue gas 2 to pass through.
The louvre-type funnel 7 therefore forms, between every two neighbouring wall sections 14, a passage cross-section 17 of width t for the passage ofthe flue gas 2 flowing from the outside towards the funnel 7. For guiding the flue gas to the funnel 7, the gas is taken through the feed pipe 12 into a further, outer funnel 18 surrounding the louvre-type funnel 7 (arrow 19), so that the flue gas can enter the in prior region of the funnel through all the superposed passage cross-sections 17 through the louvre-type funnel 7. This flue gas entry is symbolically marked by the arrows 20. It is here already clear from FIG. 1 that the entry arrows 20 for the flue gas entering the louvre-type funnel 7 are distributed across the entire cross-section of the vessel 4. This is illustrated by the extension of the arrows 20 in the form of the combined arrows 21. Therefore, the flue gas 2 entering the moving-bed reactor can be distributed across the entire cross-section by means of the louvre-type funnel 7, without additional inflow trays being required inside the reactor. The louvre-type funnel 7 itself thus serves as an inflow tray andhence distributor tray.
In place of the outer funnel 18 which surrounds the actual louvre-type massflux funnel 7, the funnel 7 can also be surrounded by a cylindrical shell 18'. This is indicated by the broken lines in FIG. 1. In the bottom outletregion 8, there is, between the outer funnel 18, 18' and the inner funnel 7, an annular gap 64 through which any loose material, which may pass intothis interspace during the charging step of the reactor, can escape or run out downwards.
The flue gas 2 must be fed to the louvre-type funnel 7 in such a way that approximately the same flue gas rate enters the interior of the loose-material reactor from each passage cross-section 17. For this purpose, the cross-sectional width t of the passage cross-section 17 can vary over the height h 3 of the funnel 7, i.e. the flow cross-section is selected such that the desired flow in the loose-material reactor is estabished. If the flue gas 2 is fed to the vessel 4 by the the feed pipe 12 in the upper region of the funnel 7, the flue gas must move downwards to the lower wall sections of the funnel 7 with a certain pressure drop. Consequently, the lower passage cross-sections 17 would have to be designed larger than the upper passage cross-sections on the louvre-type funnel 7. In FIG. 1, the lower passage cross-section 17' of width t 1 is therefore greater than the upper passage cross-section 17'' of a smaller passage cross-section t 2 .
The flue gas entering the loose-material reactor in the lower region of thelouvre-type funnel must also pass through a greater rise in height within the loose-material reactor through the loose material itself, which likewise leads to an additional pressure drop. From this aspect also, the passage cross-section 17 must therefore increase downwards between the wall sections 14, in order to reduce the flow resistance.
The illustrative example according to FIG. 2 does not differ in principle from that according to FIG. 1. In addition to the illustrative example according to FIG. 1, a further inflow tray 22, which in its design corresponds in principle to the inflow trays in DE 3,732,576 Al, is provided inside the loose-material reactor, i.e. inside the vessel 4. The gas 23 fed to this additional inflow tray flows into individual, roof-shaped distributor elements 24 and from the latter, in the most uniform distribution possible, into the reactor space (arrow 25). The angle β must here be fixed in such a way that undisturbed mass flux is again established between the roof-shaped internals. The lower louvre-type funnel 7 is of the same design as described for FIG. 1, i.e. the flue gas 2 fed to this funnel flows uniformly upwards in the loose-material reactor, corresponding to the arrows 20.
In the illustrative example according to FIG. 1 and FIG. 2, the flue gas treated in the loose material 3 flows out of the surface 26 of the loose material (arrow 27) in the upper region of the vessel 4 and passes throughthe discharge pipe 13 as treated flue gas 2' to the outside. In FIG. 2, a dust precipitation device 28 is additionally provided downstream, which separates further dust particles from the flue gas. The flue gas 2'' thus purified passes via the outlet 29 into the open or into a further treatment stage. A recycling device 30 or disposal device 30 for the precipitated dust particles can be provided in the lower region
According to the illustration in FIGS. 3a and 3b, the moving-bed reactors 1according to the invention can be interconnected to form a combined installation, the lower reactor 32 forming the first reaction stage and the upper reactor 33 forming the second reaction stage in a series connection. Thus, the flue gas 2 can be fed to the lower louvre-type funnel 7 and flow through the first reaction stage of the moving-bed reactor 32 and leave at the surface thereof according to arrow 27. In FIG.3a, this flue gas 27 flowing out and already purified in the first reactionstage 32 passes directly upwards and reaches the upper louvre-type funnel 7' of the second reaction stage 33. In the illustrative example of FIG. 3b, a partition 34 is located between the lower reaction stage 32 and the upper reaction stage 33, so that the gas 27 flowing out of the lower reaction stage 32 can be fed to the stage located above via a by-pass line35. A second gas 36 can then be fed into the upper reaction stage both in the illustrative example according to FIG. 3 a and that according to FIG. 3b, which second gas then acts only in the upper, second reaction stage 33. The gas 36 must then pass, like the flue gas 27 already purified in the first reaction stage, through the upper louvre-type funnel 7' and reaches the upper loose-material reactor of the upper reaction stage 33. In the illustrative example according to FIG. 3b, the gas 36 additionally fed to the upper reaction stage 33 can, because of the partition 34, not come into contact with the lower reaction stage 32.
The illustrative example of the invention according to FIG. 4 again concerns two superposed moving-bed reactors 1 which, however, are of the same structure in principle and form an overall installation 37. In contrast to the series arrangement of the two reaction stages 32, 33 in FIGS. 3a, 3b, however, the illustrative example according to FIG. 4 represents a parallel arrangement of these superposed loose-material reactors. Loose material 3 is fed to both the upper reactor 38 and to the lower reactor 39 via the upper charging funnel 5, the lower reactor 39 receiving this loose material via a central pipe 40 which runs through thecentre of the entire upper reactor 38 and leads into the lower reactor 39. The upper reactor 38 is supplied with loose material 3 through the annulargap 41 surrounding the central pipe 40. Mass flux of the loose material 3 prevails in both the upper and lower reactors 38, 39. The loose material 3discharged from the lower region of the upper reactor 38 reaches, after passing through the louvre-type funnel 7, a cylindrical take-off space 42 leading into a further central pipe 43 which passes through the centre of the lower reactor 39. The loose material of the upper reactor 38 thereforeflows only through this reactor and then through the central pipe 43, whereas the loose material of the lower reactor 39 likewise flows only through this reactor, since it is fed to the latter through the central pipe 40.
In order likewise to ensure mass flux of the loose material 3 at the outflow from the upper reactor 38 in the cylindrical take-off space 42 with a funnel-shaped lower extension 44, this outflow is taken symmetrically downwards into the central pipe 43. For this purpose, the central pipe 40 otherwise penetrating the upper reactor 38 symmetrically has in this region a bend 45 which leads into an annular gap 46. In the lower region of the lower reactor 39, the loose material from the upper reactor 38 leaves through the central pipe 43 (arrow 47), whereas the loose material from the lower reactor 39 leaves via the annular gap 48 surrounding the central pipe 43 (arrow 49). The loose material is thus guided separately in the upper and lower reactors 38, 39. Mass flux prevails in both reactors.
The flue gas 2 flowing to the installation 37 is divided in a branch 50 into a part stream 51 and a part stream 52 and passed via adjustable restrictor flaps 53 to both the lower reactor 39 and the upper reactor 38.Feeding is here again effected in the manner of the installation described in FIG. 1, i.e. via a louvre-type funnel 7. The superposed reactors are accordingly operated in parallel, the flue gas 2' treated in either of thereactors 38, 39 being fed in each case in the upper region to a discharge pipe 13. This purified flue gas is then fed to a common discharge line 53.
In the illustrative example according to FIG. 5, the reactors superposed inFIG. 4 but operated in parallel are connected side by side in a multiplicity to form an overall installation 54. In this case, two superposed reactors in each case are connected in the way described by reference to the illustrative example according to FIG. 4. Consequently, loose material is fed from a common loose-material container 56 to each upper reactor 38 by means of a feed line 55 common to each upper reactor 38 and lower reactor 39, which material in each case runs only through oneof the two reactors 38, 39 and is discharged in common at the lower discharge opening 57 onto a conveyor belt 58. As described with reference to FIG. 4, the flue gas 2 to be treated is separated at a branch 50 into alower part stream 51 and an upper part stream 52 which, according to the installation in FIG. 5, is again divided into further part streams 61, 62 at a lower branch 59 and an upper branch 60. These part streams 61, 62 then pass to the particular louvre-type funnels 7 of each individual moving-bed reactor. Accordingly, the gas to be purified flows through onlya single moving-bed reactor and, at the particular upper end, passes into the discharge pipe 13 and from there via an outlet line 63 to a common discharge line 53.
The illustrative example according to FIG. 5 therefore represents moving-bed reactors which are connected in parallel and are arranged both above one another and next to one another.
The invention is not restricted to the illustrative example described and shown. Rather, it also comprises all skilled further developments without independent inventive content.
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A moving bed reactor for the treatment of fluid in a countercurrent process includes a reactor vessel having, in an upper region thereof, an inlet for receiving particulate material and an outlet for discharging treated fluid, the reactor vessel also having, in a lower region thereof, a downward tapering first funnel leading to an outlet, the first funnel guiding the particulate material to the outlet for discharge from the reactor vessel, the first funnel being formed by wall sections which mutually overlap in louvre fashion to create slot-shaped passages for the fluid to be treated to enter the vessel. A second funnel is provided, surrounding the first funnel and communicating with the slot-shaped passages, the second funnel having an inlet for receiving the fluid to be treated, there being provided an annular canal between the second funnel and the first funnel at the lower regions thereof, which annular canal communicates with the particulate discharge outlet so that any particulate material which enters the second funnel by the slot-shaped passages is guided to the particulate discharge outlet through the annular canal.
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FIELD OF THE INVENTION
[0001] The invention relates to biocial compositions derived from natural products and uses thereof.
BACKGROUND TO THE INVENTION
[0002] Biocides are used in the food industry, public & private health sectors, animal health, human and animal hygiene and wound care products to reduce or eliminate pathogenic microorganisms to decrease the likelihood of human or animal exposure to such infectious agents. Biocide use in the control of zoonotic pathogens has increased following an EU-wide ban (in 2006) on the use of preservatives and synthetic antimicrobial compounds as growth promoters in animal feed and the decline in available biocides under the EU Biocide Product Registry. Low concentrations of biocides often act bacteriostatically and are only bacteriocidal at higher concentrations. Susceptible bacterial isolates acquire increased tolerance to biocides (biocide resistance) following serial transfer in growth media containing sub-inhibitory concentrations. Biocides displaying some bacterial resistance include QACs, bisbiguanides, biamidines, bisphenol, and acridines. Recently the emergence of biocide tolerant bacteria has been reported. Increasing tolerance to commonly used biocides may have an impact on a bacterium's response to food processing stresses such as heat, pH and others which are designed to reduce the risk to the consumer. Such a development may also enhance the virulence of particular zoonotic bacterial strains or may contribute to the enhancement of resistance to antimicrobial compounds, particularly those of critical importance to human health, such as the cephalosporins, fluoroquinolones and macrolides. Such zoonotic pathogens may exhibit an enhanced persistence and dissemination capacity via the food chain thereby posing an increased risk to consumer health. Current biocides range from chemicals such as alcohols, chlorine and its derivatives to ozone, hypochlorite and QACs. Each has associated positive and negative effects, including toxic by-products, poor biofilm penetration, corrosiveness, instability etc. Many are inherently unsuitable for certain applications, particularly so in the case of food production and public healthcare. Accordingly, new biocide products that demonstrate high target efficacy, with a low risk non-target toxicity and limited direct and antibiotic resistance development are required. Phytochemicals can have antimicrobial properties, but large-scale production ensuring consistent quality and efficacy at a manageable cost, along with formulations that permit diverse delivery and supports parallel mechanisms represents a technical and commercial challenge. Furthermore, phytochemicals generally suffer from incomplete characterisation and analysis, and potential non-sustainable responses. Plant antimicrobials are indigenously generated to manage bacteria and provide an evolutionary history and evidence of effective biocidal properties. For example, curromycins, cinnabarimides and oxazolomycins are also natural products with strong anti-bacterial activity. Another important class are plant polyphenols, which are secondary metabolites that can range from simple molecules, such as phenolic acids, to highly polymerized constituents such as tannins. Polyphenol derivatives in the plant kingdom are diverse, from fungi to Angiospermae, including food plants, and are common components in the human diet. All the phenolics, but especially flavonoids, have been reported to have multiple biological effects such as antioxidant activity, anti-inflammatory action, inhibition of platelet aggregation, inhibition of mast cell histamine release, and antimicrobial activities.
[0003] Phenolic flavonoids may employ a number of antimicrobial mechanisms, but are largely considered as membrane-active ‘biocides’ by which, they moderate the cell wall, penetrate the cell, and can react with the cytoplasm and cellular proteins. Phenolic compounds are optimally biocidal active in an undissociated state in acidic and neutral media.
OBJECT OF THE INVENTION
[0004] It is an object of the invention to provide a low cost, highly active natural product based biocidal formulation with low non-microbial toxicity, yet high biocidial activity against a wide range of microbes including bacteria, biofilms, fungi, spores, viruses, and particularly against gut flora, etc., for use in a wide range of applications in various environments. It is a further object of the invention to provide such formulations having anti-viral, fungal or mycoplasma properties. It is a further object of the invention to provide a biocide formulation that has low risk of development of biocide resistance and secondary antibiotic resistance.
SUMMARY OF THE INVENTION
[0005] In one aspect of the invention, there is provided a process for preparing a non-microbial non toxic biocidal composition concentrate (designated hereafter as “C-Activ-NF”) comprising the steps of:
(i) dissolving at least one polyol in water to form a water/polyol co-solvent solution; (ii) adding at least one organic acid to the water/polyol co-solvent solution, adding each organic acid sequentially, if more than one organic acid is used; (iii) adding at least one stabiliser to the water/polyol co-solvent solution; and (iv) adding at least one water soluble flavonoid or at least one aqueous plant and/or fruit flavonoid extract, to form a non-microbe non-toxic biocide concentrate.
[0010] Suitably, the process steps are carried out sequentially, and in the order as described above. Preferably, the solutions formed are stirred after each addition until all powders are dissolved. To optimise and maximise dilution, mixing is preferably carried out by a rotator mixing process. Suitably, a minimum 20 RPMs (rotations per minute) is used, with optimum blending occurring typically between 60 and 80 rpm. Such speeds optimise and maximise dilution efficiency and prevent dissapation of critical ingredients. Low speed (60 to 80 rpm) mixing ensures that aeration and flocculation are minimised Desirably, the step of dissolving at least one polyol in water to form a water/polyol co-solvent solution is carried out from about 45° C. to about 55° C., preferably about 50° C. Desirably still, the step of adding at least one organic acid to the water/polyol co-solvent solution is carried out from about 45° C. to about 55° C., preferably about 50° C. Further desirably, the step of adding the flavonoid or flavonoid extract is carried out from about 45° C. to about 55° C., preferably about 50° C. Preferably, stirring occurs for typical processing time of from about 8 hours to about 24 hours per 1,000 litre/kg to 10,000 litre/kg blends. The latter is dependent on an appropriate processing vessel. Dissolution of at least one polyol in water to form a water/polyol co-solvent solution is carried out from about 45° C. to about 55° C., preferably about 50° C. while addition of organic acids to the water/polyol co-solvent solution is carried out from about 45° C. to about 55° C., preferably about 50° C. Furthermore, the step of adding flavonoid is conducted from about 45° C. to about 55° C., preferably about 50° C.
[0011] The components are added in the quantities defined below, such that the final pH of the composition ranges are preferably from about 1.0 to about 7.0, preferably from about 1.0 to about 6.0, preferably from about 3.0 to about 5.0, preferably from about 3.0 to about 5.0, but most preferably from about 1.0 to about 2.9, more preferably still from about 1.0 to about 2.0, depending on the degree of dilution. Preferably, the final pH of the concentrate (NF) ranges from about 1.0 to less than 3, preferably from about 1.3 to less than 2, preferably from about 1.5 to about 1.9, preferably from about 1.6 to about 1.8. The more concentrate the composition, the lower the pH. In some embodiments, it is preferred that the mixture is not neutralized, as a highly acidic composition is preferred. In certain applications, neutralisation has been shown not to affect the activity and so slightly acidic to neutral solutions as described above can be used. In the concentrate, the flavonoid concentration (or flavonoid extract concentration) when measured by UV, is preferably greater than 2.5% w/w., more preferably is about 3 to 12%, more preferably from about 4 to 10%, and most preferably still about 4.5 to 6.5, most preferably 5% w/w. The total acids content is preferably greater than 35% w/w. The polyol content is preferably less than 25% w/w. Suitably, the water content is preferably less than 35% w/w. Preferably, the concentrate has a specific gravity at 20° C. of from about 1.20 to about 1.25. Preferably, the viscosity of the concentrate at 20° C. is about 20 to about 100 cP. The process provides a biocial composition concentrate (“C-Activ-NF”), which is easy to store, ready for direct use, or for dilution, or as an active substance for inclusion in commercial products, such as hygiene products, foods, animal feeds etc. The concentrate itself, and active dilutions (working solutions) of the concentrate (hereinafter designated as “C-Activ-12”) have unexpectedly good biocidal activity against both Gram positive and negative bacteria, viruses, fungi, fungal spores and even biofilms.
[0012] In a second aspect of the invention, an active working solution of the biocidal composition may be prepared by:
(i) dissolving at least one organic acid in water to form a 10% w/w solution of organic acid; (ii) dissolving a biocidal composition concentrate (C-Activ-NF) into the solution of step (i); (iii) diluting the solution formed in step (ii) with water,
to form an active working solution of a non-microbial non toxic biocidal composition comprising a 1/10 concentration of the biocidal composition (NF). Suitably, the process steps are carried out sequentially. Preferably, the organic acid is added at a concentration of about 8-12% w/w, preferably 10% w/w of the active biocidal solution. Preferably, the organic acid is citric acid. Preferably, the biocidal composition concentrate is added at a concentration of about 8-15% w/w, preferably about 10-12% w/w, preferably about 10.1-12% w/w, preferably about 10.1-11% w/w, and most preferably at 10% w/w of the active biocidal solution. The remaining component (80% w/w) is water. Preferably, the optimum active biocide composition has about 10% concentrate, about 10% citric acid and about 80% water. The pH of the active working solution is preferably from about 2.0 to about 7, about 2.0 to about 3.5, preferably from about 2.0 to less than 3.0, preferably from about 2.0 to about 2.9, or from about 2.0 to about 2.8, from about 2.0 to about 2.5, from about 2.2 to about 2.5. In one embodiment, where neutralisation occurs, the pH may be about 3 to about 7. In a preferred embodiment, a 5% aqueous solution of the working solution may have a pH of from about 2.0 to less than 3.0, preferably from about 2.0 to about 2.9, or from about 2.0 to about 2.8, from about 2.0 to about 2.5, from about 2.2 to about 2.5.
[0016] In a related aspect, there is provided a composition suitable for direct use as a biocide (concentrate: C-Activ-NF) or for use in preparing an active working biocide composition (working solution C-activ-12) comprising:
at least one water soluble flavonoid compound, optionally in the form of an aqueous fruit or plant flavonoid extract; at least one organic acid; at least one polyol; and at least one stabilizer; and the remainder of the composition is water.
[0022] In a preferred embodiment, there is provided a non-microbial non-toxic biocidal composition, having a pH in the range of from about 1 to 2.9, more preferably from about 1 to 2, comprising:
from about 0.1% to about 15% w/w of at least one water soluble flavonoid compound, optionally in the form of an aqueous plant part extract comprising at least one flavonoid; from about 8% w/w to about 12% w/w of at least one organic acid; from about 30% w/w to about 50% w/w of at least one polyol; and from about 5% w/w to about 10% w/w of at least one stabilizer; and the remainder of the composition is water.
[0028] Preferably, the composition has a pH in the range of from 1.0 to 2.0. When the former composition is diluted ( 1/10) to provide the later active working biocide composition, the active working composition has a pH in the range described above.
[0029] Accordingly, in a preferred embodiment, there is provided a working active composition, wherein the composition concentrate above is diluted with water/organic acid solution, and comprises:
from about 0.01% to about 1.5% w/w of at least one water soluble flavonoid compound, optionally in the form of an aqueous plant part extract comprising at least one flavonoid; from about 11.5% w/w to about 22.5% w/w of a first organic acid; from about 1.5% w/w to about 2.5% w/w of a second organic acid; from about 1% w/w to about 1.5% w/w of at least one polyol; and from about 0.5% w/w to about 1% w/w of at least one stabilizer; and the remainder of the composition is water.
[0036] Preferably, each of the biocial composition concentrate “C-Activ-NF” and the active diluted biocidal composition “C-Activ-12” comprise at least one flavonoid selected from: poncirin, neoeriocitrin, isonaringin, rhoiflin, naringen, neodiosmin, hesperidin, neohesperidin or naringenin Suitably, a mixture of two or more flavonoids selected from: poncirin, neoeriocitrin, isonaringin, rhoiflin, naringen, neodiosmin, hesperidin, neohesperidin and naringenin are present. In a particularly preferred embodiment, the composition comprises at least poncirin, neoeriocitrin, isonaringin, rhoiflin, naringen, neodiosmin, hesperidin, neohesperidin and naringenin. The flavonoids may be added in substantially pure chemical form, or may be added as part of a natural composition or an aqueous plant extract comprising one or more of the water soluble flavonoids. Preferably, such flavonoid extract may be obtained from an aqueous extract of citrus aurantium/bitter oranges, Seville oranges, Citrus paradise and/or grapefruit. More preferably still, the extract may be from the pulp of fruit, the leaves, the flowers and/or the seeds of plants.
[0037] In a further aspect the invention provides a non-microbial non-toxic biocidal composition, having a pH in the range of from about 1 to 2.9, comprising:
from about 0.1% to about 15% w/w of at least one water soluble flavonoid compound, optionally in the form of an aqueous plant extract comprising at least one flavonoid; from about 8% w/w to about 12% w/w of at least one organic acid; from about 30% w/w to about 50% w/w of at least one polyol; and from about 5% w/w to about 10% w/w of at least one stabilizer; and
the remainder of the composition is water, wherein isonaringin and naringen make up about half of the flavonoid component. The composition may additionally comprise neoerioctrin and/or naringenin Additional flavonoids may be present selected from one or more of poncirin, rhoiflin, neodiosmin, neohesperidin or hesperidin.
[0042] The invention also provides a non-microbial non-toxic biocidal composition, having a pH in the range of from about 1 to 2.9, comprising:
from about 0.1% to about 15% w/w of at least one water soluble flavonoid compound, optionally in the form of an aqueous plant extract comprising at least one flavonoid; from about 8% w/w to about 12% w/w of at least one organic acid; from about 30% w/w to about 50% w/w of at least one polyol; and from about 5% w/w to about 10% w/w of at least one stabilizer; and
the remainder of the composition is water, wherein in excess of about 10% of the total flavonoid content is isonaringin. The composition may further comprise naringen and in a preferred embodiment isonaringin and naringen may comprise up to half of the flavonoid component. The composition may further comprise neoerioctrin and/or naringenin Additional flavonoids may be present selected from one or more of poncirin, rhoiflin, neodiosmin, neohesperidin or hesperidin.
[0047] In a still further aspect the invention provides a non-microbial non-toxic biocidal composition, having a pH in the range of from about 1 to 2.9, comprising:
from about 0.1% to about 15% w/w of at least one water soluble flavonoid compound, optionally in the form of an aqueous plant extract comprising at least one flavonoid; from about 8% w/w to about 12% w/w of at least one organic acid; from about 30% w/w to about 50% w/w of at least one polyol; and from about 5% w/w to about 10% w/w of at least one stabilizer; and
the remainder of the composition is water, wherein one flavonoid is neoeriocitrin. The composition may further comprise naringen and/or isonaringen. Additional flavonoids may be present selected from one or more of poncirin, rhoiflin, neodiosmin, neohesperidin or hesperidin.
[0052] Preferably, the total flavonoid concentration (either directly added flavonoids or a plant extract containing flavonoids) is in the range of from about 0.1% to about 15% w/w based on the total weight of the concentrate composition (NF), preferably from about 1% to about 15% w/w, preferably from 3% to about 13% w/w, preferably from about 5% to 11% w/w, preferably from about 6% to 10% w/w, and most preferably from 10% to 12% w/w based on the total weight of the composition. In one preferred example, the total flavonoid concentration is about 2.25% w/w of the concentrate, where the flavonoids are provided in the form of 5% w/w based on the total weight of the composition of a component being a suitable aqueous plant and/or fruit extract of the concentrate (the remainder of the extract is typically biomass). In one particularly preferred embodiment, the flavonoid is present in the biocide composition as a suitable aqueous plant and/or fruit extract from about 5% to about 12% w/w in the concentrate (C-Activ-NF), and at about 0.5% to about 1.2% w/w in the working composition (C-Activ-12), and from about 0.0025-about 0.012% w/w in the final working solutions based on recommended working concentrations.
[0053] Preferably, at least two flavonoids are included. Preferred flavanoids are naringen and isonaringen. Suitably, neohesperidin is included. Where naringen and neohesperidin are present, their total concentration preferably makes up less than 75%, more preferably less than 70%, preferably less than 60%, preferably less than 50%, preferably less than 40%, and most preferably less than 35% of the total bioflavonoids present in the composition. Preferably, the flavonoid components make up preferably from less than 30% w/w, more preferably from less than 15% w/w of the aqueous flavonoid extract used (when other plant components—biomass is considered). Preferably, at least three flavonoids are included. For example, where the flavonoid isonaringin is also included in the composition, the isonaringin concentration is preferably in excess of 10%, in excess of 15%, excess of 20% in excess of 35%, and most preferably in excess of 45%, but in any case less than 60%. Preferably, this component make up greater than 5% w/w, more preferably greater than 15% w/w of the aqueous flavonoid extract used (when other plant components—biomass as considered).
[0054] In a particularly preferred embodiment, there is provided a composition suitable for use as a biocide comprising: (i) at least two water soluble flavonoid compounds, optionally in the form of a flavonoid aqueous extract or composition comprising at least two water soluble flavonoids, wherein the total flavonoid concentration is in the range of from about 0.1% to about 15% w/w based on the total weight of the composition, and wherein less than 75% of the bioflavonoids are naringen and neohesperidin;
[0000] (ii) at least one organic acid;
(iii) at least one polyol; and
(iv) at least one stabilizer; and
(v) the remainder of the composition is water.
[0055] Preferably, the composition has a pH in the range as discussed above. Suitably, naringen and neohesperidin and isonaringin are present in the amount described above.
[0056] In a preferred embodiment, the polyol may be selected from: glycerine, ethylene glycol, sucrose or pentaerythritol, or mixtures thereof. The polyol component is preferably in the range of from about 15% w/w to about 25% w/w, more preferably from about 17% to about 23%, from preferably about 20% w/w to about 22% w/w, most preferably 21.5% w/w of the total composition.
[0057] Glycerine is a particularly preferred polyol. Preferably, the ratio of water to polyol in the mixture is in the range of from about 1.3:1 (water:polyol) to about 2:1 (water:polyol), most preferably the range is about 1.4:1 (water:polyol), and most preferable still water:polyol are present in a ratio of about 1.44:1. In a further preferred embodiment, the organic acid is a fruit acid selected from: lactic acids, acetic acids, malic acids or citric acids, or mixtures thereof. Preferably, at least two organic acids are present. Preferably, the ratio of acids is from about 0.5:1.5 to 1.5:0.5. Preferably, the ratio of acids is about 1:1. Desirably, two organic acids are citric acid and malic acid. Preferably, the ratio of citric acid to malic acid is about 1:1. Suitably, the stabiliser may be selected from: ascorbic acid, uric acid or polyphenol. The function of the stabiliser may be provided by the polyol or the organic acid, or a further component which is a stabiliser, and which may or may not be a polyol or an organic acid. In other words a stabiliser is required where the polyol or organic acid in the composition does not stabilise the composition or is present in insufficient quantity for stabilisation. In a preferred embodiment, the stabilizer is present in the range of from about 5% w/w to about 10% w/w, more preferably from about 6% to about 9%, from preferably about 7% w/w to about 8% w/w, most preferably 7.52% w/w of the total composition. Preferably, the ratio of stabilizer to organic acid in the composition is in the range of from about 1:2:2 (stabilizer:organic acid:organic acid—assuming more than one is used) to about 2.5:3.2:3.2, most preferably the range is about 1:2:2 (stabilizer: organic acid: organic acid), and most preferable still 1:2:2 (ascorbic acid: malic acid: citric acid). Preferably, ascorbic acid is used as the stabiliser as it prevents oxidation of the flavonoids and accordingly increases the stability and performance of the biocide composition. In keeping with the safe and natural status of this product, only biosourced antioxidants components were employed. In a preferred embodiment, the biocide concentrate composition (C-Activ-NF) is diluted with water to a concentration of 1/10 w/w to provide an active working concentration. This concentration of product is suitable for the majority of biocide applications. The flavonoid profile of the composition typically may has the HPLC fingerprint substantially corresponding to that FIG. 2 or 3 , which measured at different concentrations. The flavonoid composition of C-Activ-NF has the HPLC fingerprint of FIG. 2 (note—it is required to dilute C-Active-NF to attain the working concentration needed for the HPLC analysis). The working composition that comprises a 1/10 dilution of the biocide concentrate of the invention has a HPLC fingerprint substantially corresponding to that of FIG. 3 (C-Activ-12). Typically the retention times and percentage of flavonoids present are evidenced by the HPLC in the concentrate under HPLC (conditions described below) comprise (a) Poncirin 15.9 minutes—3.7% (b) Neoeriocitrin 16.5 minutes—7.5% (c) Isonaringin 19.6 minutes—38.5% (d) Rhoiflin 20.4 minutes—6.6% (e) Naringen 24.1 minutes—22.7% (f) Neodiosmin 28.4 minutes—4.0% (g) Hesperidin 29.4 minutes—5.2% (h) Neohesperidin 30.2 minutes—4.6% (i) Naringenin 32.9 minutes—7.2% Typically the retention times and percentage of flavonoids present are evidenced by the HPLC of a working solution of one exemplary formulation of C-Activ-12 under HPLC (conditions described below) comprise (a) Poncirin 15.9 minutes—2.6% (b) Neoeriocitrin 16.5 minutes—4.9% (c) Isonaringin 19.6 minutes—37.7% (d) Rhoiflin 20.4 minutes—24.4% (e) Naringen 24.1 minutes—24.9% (f) Neodiosmin 28.4 minutes—4.4% (g) Hesperidin 29.4 minutes—6.0% (h) Neohesperidin 30.2 minutes—7.8% (i) Naringenin 32.9 minutes—7.3%
[0000]
Example
Dilution - ACTIVE WORKING ( 1/10) v/v
Range % w/w Ex1
Range % w/w Ex2
% w/w
Organic acid
8-12
10
NF
8-15
10
Water
Balance
Balance
Total
100%
100%
pH
2.1-2.6
2.1-2.6
Example % of
% of Total w/w
Flavonoids
Flavonoids
Flavonoid Extract
Poncirin
3.7
1.7
neoeriocitrin
7.5
3.4
isonaringin
38.5
56.6
17.3
rhoiflin
6.6
3.0
naringen
22.7
10.2
neodiosmin
4.0
1.8
hesperidin
5.2
3.5
2.3
neohesperidin
4.6
6.75
2.1
naringenin
7.2
25.9
3.2
Other plant components
—
55
Total
100
100
[0058] For the most part, the flavonoid component is made up of mostly isonaringin, followed by naringen which preferably make up about half (about 50%) of the flavonoid component. The third preferred flavonoid is neohesperidin, although levels of same are only required from about 4% upwards. Other examples of the working active indicate isonaringen present at 56.5%, naringen at 25.9%, hesperiden at 3.5% and neohesperiden at 6.75%. Proportional composition has been found to be similar in concentrate and working active wherein total naringen and neohesperiden is about 33%.
[0000]
NF Concentrate
Flavonoid Ex
5% w/w Total Composition with % w/w Flavonoid in Extract
Flavonoid
3-15
4-13
5-11
6-10
10-12
45
Content
Naringen &
Maximum less than 75% of flavonoid total
Neohesperidin
Isonaringin
Minimum in excess of 25% of flavonoid total
Range % w/w
Range % w/w
Range % w/w
Range % w/w
% w/w
% (w/w)
(Organic acids)
(30-40)
(35.04)
malic
15-20
15-17
16-18
17-19
−18-20
17.52
citric
15-20
15-17
16-18
17-19
18-20
17.52
Polyol
15-25
11-14
20-22
13-14
13.5-13.7
21.52
Stabilizer
5-10
6-9
7-8
8-9
9-10
7.52
Water
Balance
Balance
Balance
Balance
Balance
Balance
Total
100%
100%
100%
100%
100%
pH
1.0-2.0
1.0-2.0
1.0-2.0
1.0-2.0
1.0-2.0
Typical optimal % composition
Component
% per NF
% per E12
RO water
31
83.1
Polyol
21.5
2.15
Stabiliser
7.5
0.75
Citric Acid
17.5
11.75
Malic Acid
17.5
1.75
Flavonoid Extract
5
0.5
[0059] The composition may further comprise at least one other components/adjuvant selected from surfactants, for example SDS, alcohols, coatings, bleach etc. The compositions may further comprise at least one acceptable carrier, preferably those safe for use in food and water applications. The composition of the invention may also be formulated with various delivery technologies to kill harmful organisms in the food sector from farm to fork, in human health and animal health, human and animal hygiene products, protective coatings and surface sanitisation. The product has also been successfully added to drinking water for poultry reducing loadings of harmful bacteria in the gut of the bird and is approved as a potable water treatment, non-rinse surface sanitizer and food processing aid in Australia & New Zealand. The composition may be formulated for use in an aerosol dispenser, or with other liquids for disinfection, in the form of encapsulated granule, capsule suspension, emulsifiable concentrates, emulsions for seed treatment, flowable concentrate for seed treatment, cold or hot fogging concentrate, solution for seed treatment, suspension/flowable concentrate, soluble concentrate (see OECD monograph guidance March 2001 for more details).
[0060] The biocide composition C-Activ-12 prepared from the composition concentrate (C-Activ-NF) of the invention has been consistently found to be very active against both gram positive and gram-negative bacteria, and thus as a natural biocide represents a welcome alternative from existing available chemically synthesised biocides such as chlorine, ammonia, sodium hypochlorite, etc. The compositions find use as a biocide, as a sanitiser, in human or animal hygiene products/biocidal products, veterinary hygiene biocidal, as an antimicrobial or as a disinfectant against microbes, planktonics, fungi, fungal spores or biofilms. Further uses include a food sanitiser or a wash for food produce such as salads, vegetables, fruit and plants, poultry and meat carcasses, as a barrier protectant, as a poultry processing aid such as a wash or spray, a drinking water additive for animals, surface sterilizers or disinfectant for surface and equipment. In a further embodiment, the composition may be used in packaging for storage for extension of shelf life & growth inhibition. In a further embodiment still, the composition may be used in biosecurity & environmental management of microorganisms or in private area and public health areas disinfectants, as and as food and feed area disinfectants, as a drinking water disinfectant for human and animal consumption, or as a potable water treatment. Other uses include preservative applications such as preservatives for food or feedstocks, in-can preservatives, film preservatives/packaging, polymerised materials preservatives, preservatives for liquid-cooling and processing systems, crop and plant protection products. The can also be used as biocidal formulations that protect general hard surfaces and that has activity against antibiotic resistance bacteria for use in public health applications. The composition provide a biocidal formulation which has highly adaptive protective properties suitable for food applications (e.g. processing, preparation and preservation) and ensure extended mechanisms of action rendering the formulations suitable for use on food, in food and on food production surfaces, processing surfaces, water treatment and other related food sector treatment applications. They can also be used to treat wounds and infections.
[0061] In a preferred embodiment the biocide is active against gram positive and/or gram negative bacteria. Activity is against at least one bacterial species selected from the group consisting of: Salmonella, Campylobacter, Enterococcus, Listeria monocytogenes, Pseudomonas, Escherichia and Stapylococcus and Pseudomonas . In a preferred embodiment the biocide is used against at least one bacterial strain selected from the group consisting of: Salmonella typhimurium, Campylobacter jejuni, Enterococcus hirae, Listeria monocytogenes, Pseudomonas aeruginosa, Escherichia coli and Stapylococcus aureus, C. sakazakii, S. pollorum, P. cangingivalis, P. Salivosa, F. nucleatum, Eikenella corrodens, Bacteroides fragilis, Prevotella intermedia, Porphyromonas gingivalis, Tanerrella forsythensis, Cronobacter sakazakii . In a preferred embodiment the biocide is effective against fungi, powdery mildew, botrytis and Penicillium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0062] FIG. 1 illustrates a HPLC chromatogram of a standard solution of the bioflavonoid standard solution at 250 ppm concentration;
[0063] FIG. 2 illustrates a HPLC chromatogram of the “C-Activ-NF” biocide concentrate composition of the invention at a 1/1000 dilution;
[0064] FIG. 3 illustrates a HPLC chromatogram of the “CeBeC Active 12 (C-Activ-12)”) biocide composition of the invention at a 1/100 dilution;
[0065] FIG. 4 illustrate typical HPLC conditions used for analysis.
[0066] FIG. 5 : Replicate MIC analysis of E12 relative to other antimicrobials;
[0067] FIG. 6 : Salmonella Biocide Susceptibility (8 biocides relative to C-Activ-12);
[0068] FIG. 7 : Surface Dried Salmonella Susceptibility (8 biocides relative to C-Activ-12);
[0069] FIG. 8 : Salmonella Biofilm Susceptibility;
[0070] FIG. 9 : Cronobacter biocide susceptibility;
[0071] FIG. 10 : Surface dried Cronobacter susceptibility;
[0072] FIG. 11 : Cronobacter biofilm susceptibility;
[0073] FIG. 12 : pH Tolerance C-Activ-12 (E12);
[0074] FIG. 13 : pH Tolerance C-Activ-12 (E12)—replicate;
[0075] FIG. 14 : Heat Tolerance of C-Activ-12 (E12) when compared to other Active Substances/Essential Oils;
[0076] FIG. 15 : Heat Tolerance of C-Activ-12 (E12) when compared to other Active Substances/Essential Oils;
[0077] FIG. 16 : Heat Tolerance of C-Activ-12 (E12) when compared to other Active Substances/Essential Oils;
[0078] FIG. 17 : Heat Tolerance of C-Activ-12 (E12) when compared to other Active Substances/Essential Oils;
[0079] FIG. 18 : Heat Tolerance of C-Activ-12 (E12) when compared to other Active Substances/Essential Oils;
[0080] FIG. 19 : Heat Tolerance of C-Activ-12 (E12) when compared to other Active Substances/Essential Oils;
[0081] FIG. 20 : E. coli growth curve in the presence of C-Activ-12 and eugenol (phenyl propanoid);
[0082] FIG. 21 : Biological & conventional salad exposed to Kanamycin resistant E. coli —C-Activ-12 showed highest log reduction;
[0083] FIG. 22 : Biological & conventional Salad subject to Wash Plate Count Agar—C-Activ 12 showed highest log reduction;
[0084] FIG. 23 : Cl and I antimicrobial activity;
[0085] FIG. 24 : Sensitivity to iodine ( E. coli );
[0086] FIG. 25 : Sensitivity to chlorine ( S. enteritidis );
[0087] FIG. 26 : Sensitivity to iodine ( S. enteritidis );
[0088] FIG. 27 : Sensitivity to sodium hypochlorite ( E. coli );
[0089] FIG. 28 : Sensitivity to C-activ-12 ( E. coli );
[0090] FIG. 29 : Sensitivity to C-Activ-12 ( S. enteritidis );
[0091] FIG. 30 : Powdery mildew ( Uncinula necator ) on cucumber leaf in the presence of a 300-1 of 2% C-Activ-12. C-Activ-12 inhibited fungal activity;
[0092] FIG. 31 : Antimicrobial activity
DETAILED DESCRIPTION OF THE INVENTION
[0093] The Cebec research, formulation work and initial testing that was performed, which led to and drove the development of this new biocide product, C-Activ-NF & C-Activ-12, were conducted in 2009. Abbreviations—ATCC=American Type Culture Collection, BSA=Bovine Serum Albumin, BSEN=British Standard European Norm, CFU=Colony Forming Units, CNMR=Centre for Nanotechnology and Materials Research, E12=Laboratory code for C-Activ-12, FDA=Food & Drug Administration, GRAS=Generally Recognised As Safe, MIC=Minimum Inhibitory Concentration, mM=milliMolar, NaCl=Sodium chloride, NCTC=National Collection of Type Cultures, ° C.=degree celsius, ppm=parts per million, spp=species, TNTC=To Numerous To Count, TSA=Tryptic Soy Agar, v/v=volume/volume, w/v=weight/volume The Inventors have developed a stable, highly active natural product biocide composition concentrate known as C-Activ-NF and a working concentrate solution known as C-Activ-12. The preferred biocide composition concentrate (C-Activ-NF) of the invention consists of at least one natural organic acids, (for example, malic acid, citric acid), at least one polyol, (for example glycerine), and at least one antioxidant, (for example ascorbic acid), together one or more flavonoid compounds (for example, hesperidin, naringin, isonaringin, etc.) or a flavonoid extract from a suitable source such as one or more of citrus aurantium/bitter oranges, Seville oranges, Citrus paradise and or grapefruit, and particularly, extracts from the pulp of fruit, the leaves, the flowers and seeds of plants. The flavonoids were extracted from selected citrus fruits of a particular age range and time of year, following physical disruption, by an aqueous water/methanol/ethanol solvent mix. No solvent residue was retained in final lyophilised product. Preferably, the extracts are aqueous extracts as the flavonoids of interest are a class of water-soluble active phytochemicals. Flavonoids and flavonones levels, are influenced by growing and environmental factors. Fruit sourcing factors are important in determining variations in the levels of concentration of these compounds, the quantity in immature bitter orange fruit being higher than in ripe fruit for example. The bitter orange extracts can be obtained from ground citrus fruits (especially Citrus aurantium/bitter oranges) through standardized processing operations such as extraction, filtration, concentration, precipitation, clarification and final drying. Extraction processes can be performed in cold water extraction systems, or wherein a solvent is selected from methanol, ethanol, propanol and the like. Methanol is used preferably, but not exclusively, and as such any solvent used must comply with EU Council Directive 88/344/EEC of 13 Jun. 1988 on the approximation of the laws of the Member States on extraction solvents used in the production of foodstuffs and food ingredients. The compositions of the invention were analysed using HPLC against a series of known bioflavonoid standards. A HPLC chromatogram of the standard solution used (at a concentration of 250 ppm) for fingerprinting and quality control is shown in the Figures. Raw material sourcing and processing described herein generates a stable biocial composition that displays unique and consistent biocidal properties, even at very low concs, when subject to multiple comparative assay studies. The component concentrations employed, the addition sequence, the dilution measurement techniques, the solvent volumes, the C-Activ-NF concentrate, the C-Activ-12 Active Substance working biocidal formulation, the operational dilution, were all optimised by application of multivariable formulation studies. The flavonoid components of the compositions of the invention were selected on preliminary anti-oxidant evidence, commercial viability, cost and availability. Single or multiple flavonoids components can be present in the biocide compositions of the invention. Suitably, at least naringin, isonaringin and neohesperidin are incorporated. Food grade quality is necessary for the proposed applications (such products must comply with Council Directive 78/663/EEC which specifies the standards of purity for emulsifiers, stabilizers, thickeners, and gelling agents for use in foods). Organic acids such as lactic, acetic, malic, and citric acid are included in the composition of many foods for preservation purposes. Their action on flavonoids is related to pH reduction, impediment of substrate transport, and reduction of proton motive force. The lower MW of malic acid ensures greater permeability than citric acid, but both were selected as the organic acid additives in the preferred compositions of the present invention. Flavonoids are water soluble, but at higher concentrations require incorporation of an organic solvent. The polyol glycerine is highly stable, virtually nontoxic and a non-irritant and odourless. Due to its hydroxyl groups, glycerine has solubility characteristics similar to those of water and simple aliphatic alcohols. Phenolic compounds are more soluble in glycerine than in water, and this additive was therefore selected to enhance flavonoid solubility and stability. While, free radicals may exert antimicrobial effects, they are equally likely to be cytotoxic to mammalian cells (if not locally controlled). Flavonoid stability will also be dependent on prevention of oxidation and so anti-oxidant, such as ascorbic acid was included in the formulation. This is also a common food anti-oxidant ingredient, with low secondary toxicity. Biocidal composition concentrates were prepared and sequential dilution protocols generated, but the majority of the formulation research was devoted to identifying optimal component concentrations for biocidal efficacy, requiring dilution sequences, mixing sequence and stirring duration and temperature study. The combination of starting materials and process parameters imparts unexpected antimicrobial activity to the compositions produced by the processes of the invention. The working biocidal formulation C-Activ-12 can be produced from the composition concentrate (C-Activ-NF) as described herein or it can be produced separately by adding the individual ingredients sequentially in one blending process under process blend protocols, stirring, temperature, solubility, timing, as described herein
Preferred Biocial Composition Concentrate (C-Activ-NF) Blending Protocol for Biocidal Active Substance C-Activ-12—
[0094] Most flavonoids exhibit low solubility and poor stability in both polar and nonpolar media, impeding incorporation in many formulations. The flavonoids employed herein were subject to a certain process to enhance dissolution and to provide viable and stable concentrations. The biocidal compositions of the invention are first blended as a concentrate (C-Activ-NF) for preparation of biocide, which can then be suitably diluted with an appropriate solvent, such as a composite of water and/or citric acid to generate the CeBeC Active 12 (C-Activ-12) Active Substance working biocidal composition. Typically, a dilution of 10× of the concentrate composition C-Activ-NF produces a good working solution which has been shown to have excellent biocidal activity. The working concentrate can be subjected to further selected aqueous dilution for real time activity and exposure, again, depending on the nature of the application and susceptibility of the target. In a particularly preferred embodiment, the flavonone component of the biocidal composition concentrate (C-Activ-NF) of the invention is a suitable plant part extract and is present at about 5%-about 12% (w/v) in the concentrate (C-Activ-NF), about 0.5%-about 1.2% (w/v) in C-activ-12 working composition solution, and about 0.0025-about 0.012% (w/v) in the final recommended dilutions/active concentration used in many of the tests presented herein. Examples of HPLC chromatogram of characterisation compliant products with are shown in FIGS. 2 & 3 , C-Activ-NF & C-Activ-12. All components are dissolved sequentially and added in singular addition. Sequential addition, timing and mixer conditions maximises solubility. Preferred conditions were established following the trial development of the formulation. To optimise and maximise dilution, the rotator mixing process rotates at a minimum of about 20 RPM's (rotations per minute), with optimum blending occurring typically between about 60-about 80 rpm. Stirring occurs from about 60 minutes per addition, with a typical processing time of about 8 hours to about 24 hours per 10 litres/kg to 10,000 litre/kg blends the latter being dependent on using an appropriate mixing vessel. The first part of the process can be conducted at RT (about 20° C.) for the organic acid addition steps, but is raised to about 50° C. (45° C.-55° C.) for flavonoid and polyol addition. Alternatively, the process can be started at about 50° C. (45° C.-55° C.) and maintained until all powders are fully solubilised. A maximum of 55° C., preferably 50° C. permits full dissolution in the stated timeline and imposes no operational or structural damage to the flavonoids. Temperature selection was based on evidence of composition stability at max temp, rather than extensive variable analysis. Aeration and flocculation are minimised by application of a gentle mixing process (≦60 rpm, preferably ≦60-80 rpm)) with a limited range of blending blades. Excessive aeration and flocculation as elements of sub-optimal mixing can reduce solubility and enhance flavonoid oxidation, which is visible by absorbance and colour status. Exceeding the approved temperature will potentially reduce flavonoid function and concentration and enhance vaporisation with further concentration impact and reduction of biocidal efficacy. An example of an HPLC chromatogram of a completed product compliant with C-activ-12 characterisation is shown FIG. 3 .
[0000] Preparation of C-Activ-NF Biocide Concentrate & Preferred E12/C-Activ-12 Working Solution (C-Activ-NF (Batch 25 kg))—
[0095] Add water (7.750 kg, 31% w/w) and put on stirrer (80 rpm, 50° C.). Add glycerine (5.375 kg, 21.5% w/w 50° C.) and stir for 15 minutes until flocculation disappears and solution is clear and allow system to re-attain 50° C. for minimum 10 minutes. Add malic acid (4.380 kg, 17.52% w/w, 50° C.) and stir for 30-40 minutes at min 60-80 rpm (or until the solution has become clear and solution has re-attained 50-55° C.). Add citric acid (4.380 kg, 17.52% w/w, 50° C.) and stir for 30-40 minutes at min 60-80 rpm (or until the solution has become clear and solution has re-attained 45-55° C.). Add ascorbic acid (1.880 kg, 7.52% w/w, 50° C.) and stir for 30-40 minutes at min 60-80 rpm (or until the solution has become clear and solution has re-attained 50-55° C.). Add the flavonoids extract (1.250 kg, 5% w/w of minimum 2.5% w/w flavonoids, 50° C.) and stir for 30-40 minutes at min 60-80 rpm (or until the solution has become clear and solution has re-attained 50-55° C.).
[0096] E12/C-Activ-12 (25 kg)—
[0097] Add 15 kg, 60% w/w water to tank and stir. Add 2.5 kg, 10% w/w citric acid and stir until liquid is clear (minimum 30 minutes). Add 2.5 kg, 10% w/w C-Activ-NF and stir for 30 minutes on low speed (60-80 rpm). Add a further 5 kg, 20% w/w of water and stir for 15-20 mins on low speed (60-80 rpm). Seal and Label appropriately. Checked with HPLC and LC-MS analysis to determine the bioflavonoid types present in the final formulations.
Routine Analytical, Shelf Life and Stability Data for Selected Phase 1 Formulation (Indicating Process Repeatability to Give a Stable Consistent Product and Indicates Repeatability of the Process)
[0098]
[0000]
Analytical data on the NF Batch NF09008_26FEB2010
Test Item
RESULT
Specification
Comment
pH
1.4
1.0-2.0
CONFORMS
Flavonoids Content (UV)
3.2%
>2.5%
CONFORMS
Acids Content
41.3%
>35%
CONFORMS
Glycerine Content
23.6%
<25%
CONFORMS
Water Content (LOD)
34.3%
<35%
CONFORMS
Water Solubility
Complete
Complete
CONFORMS
Appearance
Dark Brown Liquid
Dark Brown Liquid
CONFORMS
Specific Gravity @ 20° C.
1.21
1.20-1.25
CONFORMS
Viscosity @ 20° C.
47
20-100 cP
CONFORMS
Analytical data on the C-Activ-12/E12 Batch E1209008_26FEB2010
Test Item
RESULT
Comment
pH
1.8
CONFORMS
Flavonoids Content (UV)
3.2%
CONFORMS
Acids Content
14.6%
CONFORMS
Glycerine Content
2.5%
CONFORMS
Water Content (LOD)
83.4%
CONFORMS
Water Solubility
Complete
CONFORMS
Appearance
Dark Brown Liquid
CONFORMS
Stability Data - C-Activ-12 (E12) - AFTER 6 months
Month
RESULT
Comment
1
No visual change/No growth
NO PPT
2
No visual change/No growth
NO PPT
3
No visual change/No growth
NO PPT
4
No visual change/No growth
NO PPT
5
No visual change/No growth
NO PPT
6
No visual change/No growth
NO PPT
7
Small precipitation - back into solution
PPT
after shaking/No growth
8
Small precipitation - back into solution
PPT
after shaking/No growth
Stability Data - NF after 6 months
Month
RESULT
Comment
1
No visual change/No growth
NO PPT
2
No visual change/No growth
NO PPT
3
No visual change/No growth
NO PPT
4
No visual change/No growth
NO PPT
5
No visual change/No growth
NO PPT
6
No visual change/No growth
NO PPT
7
No visual change/No growth
NO PPT
8
No visual change/No growth
NO PPT
9
No visual change/No growth
NO PPT
Summary of Test Data Using CeBeC Active 12 (C-Activ-12)—
[0099] The C-Activ-NF concentrate composition has shown consistent efficacy against harmful micro-organisms, whilst the working solution C-Activ-12 formulation has shown consistent high log reductions of selected gram positive and negative bacterial strains, performing and meeting log reductions under BSEN1276 suspension test for chemical disinfectants and antiseptics. C-activ-12 also achieved the required log reductions under surface dried bacteria testing requirements, isolated bacteria and bacteria in bio-film, as supported under independent testing by University College Dublin Department of Food Safety & Zoonotic Diseases when the invention formulations were tested and compared against chemical based toxic products available on the market under a FIRM (Food Institutional Research Measure) Department of Food and Marine funded study. As a novel natural biocide, C-Activ-12 performed better than the chemically synthesized alternatives. The study also found that C-Activ-12 has a zero resistance profile, i.e. it does not cause mutations and has multiple modes of action, targeting a number of sites of the harmful micro-organisms, with a low MIC and a total MBC with extended exposure time. The biocial compositions of the invention have been evaluated in four separate research institutions since 2009 (as per available test & laboratory reports) with a high level of correlative agreement regarding biophysical properties and gram −ve/+ve log reduction effective profile. The tests confirm high activity of the biocides of the invention against a range of both gram-positive and gram-negative bacteria. This highlights the exceptionally useful biocidal activity of the compositions arising from the process of the invention.
Summary of Initial Biocide Findings for Highly Active CeBeC Active 12 (C-Activ-12) Composition
[0100] Initial efforts were concentrated on two zoonotic pathogens namely verocytoxigenic Escherichia coli and Salmonella species, along with the recently described powdered infant formula (PIF) pathogen Cronobacter species. All isolates analysed (in each case >100 were selected from strains recovered during various epidemiological studies) were found to be susceptible to biocides in common use in the meat and PIF industries. Some of the genera appeared to be more susceptible compared with others, as in the case of Cronobacter . Attempts to develop tolerant phenotypes were marginally successful and where this was generated, the phenotype was unstable. As a means of modelling the increased tolerance to biocide-active compounds, a small number of isolates were challenged with increasing concentrations of actives such as triclosan, chlorhexidine and benzalkonium chloride. Highly-tolerant mutant phenotypes were obtained and these are currently being studied. It was decided that it would be of interest to include the poultry food-borne zoonotic pathogen Campylobacter and to evaluate its susceptibility/tolerance to the same panel compounds. Once again, it could be shown that Campylobacter was susceptible. However, as the panel of biocidal compounds used could be described as synthetic, the availability of C-Activ-12 natural composition of the invention presented an opportunity to re-evaluate the responses of these bacteria to the natural biocide composition of the invention. Initially planktonically-growing campylobacter were tested and found to be completely susceptible to C-Activ-12 at working concentrations ranging from 0.5 through 1% (w/v). Similarly when these same cells were part of a biofilm, C-Activ-12 remained effective over the latter concentration range. These studies were subsequently extended to include Cronobacter, Salmonella and E. coli (as outlined above) and in each case the bacteria tested were found to be susceptible to the natural biocide product (C-Activ-12) at working concentrations, being bacteriocidal in all cases. C Activ-12 has also been subject to an in vivo poultry trial to assess its capacity to moderate indigenous Campylobacter population (Foundation of Research Science & Technology (New Zealand)—Study on Broiler Chickens at the University of Sydney, trial conducted by Dr Peter Groves Vice of the Poultry Vets Association). In a preliminary anti- Campylobacter live poultry trial, 800 one day old broiler chicks were exposed to low sub-approval dose (0.1%/1,000 ppm) to test C-Activ-12 biocide in drinking water over a controlled 42 day trial. The addition of C Activ-12 to drinking water continuously for broiler chickens showed no deleterious effects the birds, on growth rate, feed efficiency or visceral organ weights, and was readily consumed by the birds. A major mediator of poultry Campylobacter transfer infection is exposure to contaminated faeces. In this pre-trial, there was a significant decline in the level of C. jejuni in the caecae (the gut of the bird) consistent with the level found in faeces, this was inversely associated with the dose rate of C Activ-12 after a simulated transport stress. Furthermore, propagation of Campylobacter infestation of poultry is influenced by faecal release (Ogden et al 2009). The biocide composition at working concentration in this project has shown a capacity at sub-MIC concentration in an independent animal trial to significantly reduce faecal bacterial density and also exhibited a high capacity to terminate a recently evaluated food pathogen in Dairy processing called Cronobacter species.
Further Biocide Activity Studies
[0101] Six bacterial strains were tested according to BS EN 1276, at working concentration of ≦1% (w/v), namely Salmonella typhimurium ATCC 14028 Enterococcus hirae ATCC 8048, Listeria monocytogenes NCTC 11994, Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 25922 and Stapylococcus aureus ATCC 25923. The gram −ve Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa , reproducibly showed a 5 log 10 reduction at the biocidal composition working concentration, while the gram +ve strains (all of which are clinically relevant) showed a 6 log 10 decline.
[0102] In a further study, a number of biocide compositions at 1% to 2% concentrations were tested against a set of five similar enteric pathogens, Campylobacter jejuni NCTC 11392 C. sakazakii ATCC 13076, S. typhimurium CCC2, E. coli NCTC 1093, S. pollorum ATCC 19945, using a well diffusion assay (Martin et al. (2009)). All strains demonstrated clear susceptibility to the biocide composition of the invention. In the case of the enteric pathogens/surrogates inhibition zones >3 mm were consistently recorded over 3 replicates when tested against the biocide (1:10 dilution corresponding to a working concentration of the biocide composition concentrate of the invention). The zones of clearing were tested for bacteriocidal/bacteristatic activity by stabbing the zone of clearing and streaking on to non-selective agar followed by selective agar. No growth was observed from the zones of clearing. While only one replicate was carried out for the dental pathogen, the biocide composition of the invention also proved effective against the majority of the dental pathogens. On average about 2 mm zones of clearing were observed when tested against the “working composition” (1:10 dilution). Again all zones of clearing tested suggested that the activity at this level was bacteriocidal at the 1/10 working concentration of biocide.
[0103] In an efficacy stability study measured against E. coli , the biocide composition showed functional stability after been frozen and thawed (between 0 and 42° C. for ˜24 hrs) and after heating up and cooling.
[0104] In a separate study (Epidimiology study on Campylobacter Isolates in the Republic of Ireland, UCD; University of Sydney study testing the reductions of the biocidal composition of reducing the numbers of Campylobacter and Salmonella in Poultry), employing high throughput screening of natural isolates of and the other wildtypes samples isolated in an epidemiology study of poultry highlighted the efficacy of the natural biocide of the invention. No growth was uniquely recorded at 0.5 and 1% operative concentrations of the biocide. It was not confirmed, whether the latter was bacteriostatic or bacteriocidal. However, a study undertaken by a partner has provided dose evidence of significant bacteriocidal actions.
Evaluation of Bactericidal Efficacy of the Biocide Compositions of the Invention
[0105] Tests have indicated that the compositions of the invention act as broad spectrum anti-bacterial agents effective against gram positive and gram negative bacteria (BSEN 1276). The compositions are suitable for use in the food and food processing industry. For rapid screening, a preliminary method allowed selection of the most efficient formulations. Two prototypes (E12 and G3 (E12 with a surfactant component)) were then tested using the standard method. The composition of each formulation (0.5% v/v) was used blind to ensure no bias. The formulation was reviewed after each set of tests to improve the products composition and efficiency. Prototype formulations were prepared under aseptic conditions.
[0000]
Culture conditions used for bacterial strains studied
Incubation
Incubation time
Respiratory
Bacteria
Media
temperature (° C.)
(Hours)
conditions
Escherichia coli ATCC 25922 (gn)
Nutrient agar
37
24
Aerobic
Stapylococcus aureus ATCC 25923 (gp)
Nutrient agar
37
24
Aerobic
Salmonella typhimurium ATCC 14028
Nutrient agar
37
24
Aerobic
(gn)
Pseudomonas aeruginosa ATCC 15442
Nutrient agar
37
24
Aerobic
(gn)
Listeria monocytogenes NCTC 11994
Columbia blood agar
37
24
Aerobic
(gp)
Campylobacter jejuni NCTC 11392 (gn)
Blood agar base 2
42
72
Microaerophilic
Enterococcus hirae ATCC 8048 (gp)
Columbia blood agar
37
48
Aerobic
Contact Time: 5 mins ± 10 secs;
Test Temperature: 20° C. ± 0.5° C.;
Product Storage: 5° C. in the dark
Reagents:
Water: Free from toxins or bacterial inhibitors. Fresh distilled water, which had been sterilized by autoclaving.
Hard-water (Product diluent): as per Abbott Analytical - 300 mg/kg CaCO3 and sterilized by autoclaving.
Neutralising Solution: 3% (w/v) Tween 80, 3% (w/v) Saponin, 0.1% (w/v) Histidine, 0.1% (w/v) Cysteine.
Interfering Substance: (a) Clean conditions: 0.3 g BSA in 100 ml water, sterilized by membrane filtration (pore size 0.22 μm). Final concentration in the test procedure is 0.3 g/L. (b) Dirty conditions: 3 g BSA in 100 ml water, sterilized by membrane filtration. Final concentration in the test procedure is 3 g/L.
Biocidal Efficacy—
[0106] A large number of formulations comprising inter alia flavonoids and food grade acids were prepared and tested.
[0000]
09008E1
Flavonoid Mixture only
Single Strength
09008E2
Flavonoid Mixture ONLY
Double Strength
09008E3
MALIC ACID ONLY
Single Strength
09008E4
CITRIC ACID ONLY
Single Strength
09008E5
ASCORBIC ACID ONLY
Single Strength
09008E6
Normal Formulation
Cold Blended
09008E7
Normal Formulation
plus 10% EtOH
09008E8
Normal Formulation
2 × Malic Acid
09008E9
Normal Formulation
2 × Citric Acid
09008E10
Normal Formulation
2 × Ascorbic Acid
09008E11
Normal Formulation
plus 20% EtOH
09008E12
Normal Formulation
diluted to 10% + 10%
Citric Acid
09008E13
Normal Formulation
plus Double Strength
Flavonoid Mixture
09008E14
Normal Formulation
plus 2% SDS
09008E15
Normal Formulation
09008E14 plus Double Strength
Flavonoid Mixture
[0107] The most successful formulation was E12 formulation (C-activ-12). This was initially used neat as prepared from NF, as per other formulations, in concentrate form, but once it had shown effectiveness, the E12 dilutions were tested for Minimum Inhibitory Concentrations (MIC) under British & European testing standards. C-Activ-NF & C-Activ-12 were further diluted and were sent to for LC-MS analysis to compare both. The pre-blended bioflavonoid mixture starting material concentration was then doubled and the micro testing of this composition (E13) was repeated with no improvement in results. This confirms that the concentration in E12 provides the optimum activity. The addition of surfactant SDS (E14—see results below) was expected to improve activity (surfactant component would be expected to enhance cell permeability, dispersion and associated adherence), but it was found not to improve the effectiveness of the materials. Ethanol was also added (E7 and E11) with no increase in effectiveness (see results below). The following re-formulations were also performed based on the most active E12 NF composition defined above. Note when ethanol and or SDS was added to E12, it maintained its effectiveness. This was an interesting finding as it highlights that the invention can be combined with adjuvants for varying applications—refer to Campylobacter epidemiology study described herein.
[0000]
Dilution
E12
Normal Formulation
10% NF + 10% Citric Acid + 80% Water
E12+
Normal Formulation
10% NF + 10% Citric Acid +
60% Water + 20% EtOH
E12S
Normal Formulation
10% NF + 10% Citric Acid +
75% Water + 5% SDS
E12S+
Normal Formulation
10% NF + 10% Citric Acid +
55% Water + 20% EtOH + 5% SDS
E12++
Normal Formulation
10% NF + 10% Citric Acid +
40% Water + 40% EtOH
E12S++
Normal Formulation
10% NF + 10% Citric Acid +
35% Water + 40% EtOH + 5% SDS
E12C+
Normal Formulation
10% NF + 30% Citric Acid +
40% Water + 20% EtOH
[0108] Each biocidal composition was tested blind. Alter each assay the formulation was adjusted as indicated above, and retested for inhibition of bacterial growth. A number of known sanitizers and detergent cleaners (labelled V1, W2, X3, Y4 and Z5 in these test) induced a log 5 reduction in microbiological tests, and these were assessed in preliminary tests for comparison purposes or as control.
Preliminary Evaluation of Bactericidal Efficacy of CeBeC Natural Biocide Preliminary Formulations
[0109] Typically, an overnight culture of bacteria strains were diluted 1:1000 in sterile hard water to a final density of approx 1×10 6 bacteria. A 1 ml volume of bacteria was treated for 5 minutes at room temperature with 500 μl of antimicrobial solutions. The final volume was 1.5 ml so the final concentration of formulation e.g. E12 is 0.167% (v/v). The treatment was ceased by the addition of 200 μl of the neutralising solution. All strains were serially diluted to 10 −5 in sterile peptone water and 100 μl were plated in duplicate on the appropriate plate and then incubated at 37° C. for 24 hours except Campylobacter jejuni and Enterococcus hirae . The appropriate controls were included in each test e.g. an unopened agar plate and a set of serially diluted, untreated bacteria. After mesophilic aerobic incubation (or mesophilic microaerophilic incubation for C. jejuni ), the number of colonies was enumerated and compared to the untreated controls to determine if a Log order reduction was obtained.
[0000]
Antimicrobial activity of selected commercial sanitisers
as compared to solution E12 on E. coli
Escherichia coli
NEAT
10−1
10−2
10−3
10−4
10−5
10−6
Y4
TNTC
TNTC
TNTC
113
60
0
0
Z5
TNTC
TNTC
TNTC
TNTC
66
5
0
V1
TNTC
TNTC
TNTC
TNTC
0
0
0
X3
TNTC
TNTC
TNTC
TNTC
TNTC
1
0
E12
TNTC
0
0
0
0
0
0
Control
TNTC
TNTC
TNTC
TNTC
TNTC
0
0
Conclusion:
[0110] It can be concluded that solution of the biocial composition of the invention E12 induced the greatest inhibition of bacterial growth of gram-negative E. coli in this test when compared to commercial sanitizers. The efficacy order of commercial solutions tested against Escherichia coli was: E12>Y4≧V1≧Z5>X3. E12 showed most activity with a reduction of 4 Log units.
[0000]
E. coli bacterial colony counts (average of two replicates)
following 5 min exposure to 0.5% v/v of the various preliminary
biocide formulations of the invention
Antimicrobial
Bacterial Dilution
Solution
Neat
10 −1
10 −2
10 −3
10 −4
10 −5
Control
TNTC
TNTC
TNTC
TNTC
TNTC
1
E1
TNTC
TNTC
TNTC
TNTC
TNTC
TNTC
E2
TNTC
TNTC
TNTC
TNTC
>14
>5
E3
TNTC
TNTC
TNTC
TNTC
TNTC
>61
E4
TNTC
TNTC
TNTC
>159
TNTC
10
E5
TNTC
TNTC
TNTC
TNTC
TNTC
TNTC
E6
TNTC
TNTC
TNTC
TNTC
TNTC
TNTC
E7
TNTC
TNTC
TNTC
TNTC
TNTC
1
E8
TNTC
TNTC
TNTC
TNTC
TNTC
>9
E9
TNTC
TNTC
TNTC
TNTC
>113
>114
E10
TNTC
TNTC
TNTC
>82
2
2
E11
TNTC
TNTC
TNTC
TNTC
TNTC
2
E12
0
0
0
0
0
1
E13
TNTC
TNTC
TNTC
TNTC
>5
3
E14
TNTC
TNTC
TNTC
TNTC
TNTC
0
E15
TNTC
TNTC
TNTC
TNTC
TNTC
53
Conclusion:
[0111] It is evident from the results in above that the biocide formulation E12 has the most anti-microbial efficacy when treating gram −ve E. coli , with an almost complete kill at all concentrations tested. In fact, E12 (C-Activ-12) produced a five log reduction of bacterial numbers in comparison with the control. E10 was responsible for a two log reduction, whereas E2, E9, E13 and maybe E8 produced just one log reduction. In view of the excellent results of E12 formulation in the preliminary tests, it was decided to test the E12 formulation, on a number of bacterial strains, at varying concentrations to further assess its efficacy.
[0000]
Bacterial colony counts (average of two replicates)
following exposure to E12 formulations.
NEAT
10 −1
10 −2
10 −3
10 −4
10 −5
Escherichia coli
Control
TNTC
TNTC
≅450
69
14
2
E12
0
0
0
0
0
0
E12 (1/5)
TNTC
325
80
10
0
0
E12 (1/10)
TNTC
TNTC
TNTC
≅200
0
0
Salmonella typhimurium
Control
TNTC
TNTC
TNTC
140
6
1
E12
1
0
0
0
0
0
E12 (1/5)
31
TNTC
TNTC
≅200
0
0
E12 (1/10)
TNTC
TNTC
TNTC
≅282
≅119
0
Staphylococcus aureus
Control
TNTC
≅500
122
15
1
c
E12
2
3
0
0
3
0
E12 (1/5)
TNTC
≅380
46
3
1
1
E12 (1/10)
TNTC
≅400
48
5
1
0
Pseudomonas aeruginosa
Control
TNTC
TNTC
80
30
1
1
E12
0
0
0
0
0
0
Listeria monocytogenes
Control
TNTC c
TNTC
TNTC c
115
18
1
E12
0
4
1 c
0
0
0 c
Enterococcus hirea
Control
TNTC
TNTC
TNTC
91
17
0
E12
0
0
0
0
0
0
Campylobacter jejuni
Control
TNTC
TNTC
TNTC
102 c
13
4
E12
0
0
0
0
0
0
c = plate with contamination
Conclusion:
[0112] From the results it can be concluded that E12 is a very efficient formulation of the biocide composition of the invention. E12 has the ability to inhibit the growth of all Gram +ve and −ve bacterial strains tested when used as received (which is at a 0.5% v/v). A second-generation batch of formulations, which were variations of E12 and were named ‘F’ was prepared using the E12 as a starting point.
[0000]
Variations
09008F1
12 g Water + 8 g Glycerine
Bioflavonoid Mix (8 g);
Asc Acid (6 g); Malic Acid
(7 g); Citric Acid (7 g)
09008F2
12 g Water + 8 g Glycerine
Pure Naringen (4 g);
Asc Acid (3 g); Malic Acid
(7 g); Citric Acid (7 g)
09008F3
12 g Water + 8 g Glycerine
Bioflavonoid Mix (8 g);
Asc Acid (6 g); Malic Acid
(7 g); Citric Acid (17 g)
09008F4
12 g Water + 8 g Glycerine
F3 + 100,000 ppm SDS
(2 g/20 mL Water)
09008F5
12 g Water + 8 g Glycerine
F4 + 5% w/v
Hypochlorite Bleach
09008F6
E12 (1 in 10 dilution)
Not Applicable
09008F7
E12 (1 in 5 dilution)
Not Applicable
09008F8
12 g Water + 8 g Glycerine
F2 + Citric Acid @ 14 g/10 mL
09008F9
12 g Water + 8 g Glycerine
F8 + 100,000 ppm SDS
09008F10
12 g Water + 8 g Glycerine
F9 + 5% w/v Hypochlorite
Bleach
[0113] These formulations were tested against the indicator species S. typhimurium and E. coli (see results below). The most effective solutions were tested on further organisms (see results below).
[0000]
Effects of F Compostion Variant against indicators species
NEAT
10 −1
10 −2
10 −3
10 −4
10 −5
Salmonella typhimurium
Control
TNTC
TNTC
TNTC
≅239
>22
2
F1
TNTC
TNTC
TNTC
>177
40
16
F2
TNTC
TNTC
≅450
67
12
0
F3
TNTC
TNTC
≅400
80
4
1
F4
TNTC
35
4
0
0
0
F8
TNTC
TNTC
≅400
82
7
0
F9
TNTC
TNTC
232
45
>10
0
Escherichia coli
Control
TNTC
TNTC
≅450
69
14
2
F1
TNTC
TNTC
328
54
>40
0
F2
TNTC
TNTC
>157
>72
3
>3
F3
TNTC
TNTC
TNTC
>61
>13
1
F4
22
0
0
0
0
0
F8
TNTC
TNTC
192
14
1
0
F9
TNTC
>56
0
0
0
0
Staphylococcus aureus
Control
TNTC
≅500
122
15
1
c
F4
7
0
0
0
0
0
F9
3
0
0
0
0
0
P seudomonas aeruginosa
Control
TNTC
TNTC
80
30
1
1
F4
0
0
0
0
0
0
F9
8
0
0
0
0
0
Listeria monocytogenes
Control
TNTC c
TNTC
TNTC c
115
18
1
F4
75
6
0
0
1 c
0
Enterococcus hirea
Control
TNTC
TNTC
TNTC
91
17
0
F4
95
15 c
0
0
0
0
F9
TNTC
TNTC
121
>42
9
0
Campylobacter jejuni
Control
TNTC
TNTC
TNTC
102c
13
4
F4
2
0 c
0
0 c
0
0 c
Conclusion:
[0114] From the E. coli and S. typhimurium results it can be concluded that only the variations of E12, that is F4 and F9 show the best antibacterial activity. As a consequence, these 2 samples were tested on other bacterial strains that constitute the panel of organisms used in BSEN 1276. F4 produced a 5 Log reduction for E. coli, P aeruginosa and C. jejuni , a 4 Log reduction against S. aureus and L. monocytogenes and is responsible for a 3 Log reduction against S. typhimurium and E. hirae . F9 demonstrated more effective antibacterial activity against P. aeruginosa with 5 Log reduction of the bacterial population followed by E. coli and S. aureus (4 Log reductions). Unfortunately F9 was not efficient against S. typhimurium and E. hirae . Nevertheless, F4 and F9 samples contain Sodium Dodecyl Sulphate (SDS). As a consequence these solutions cannot be used to wash vegetables directly but could find application in sterilisation of worktops and equipments where food contact is indirect (SDS not suitable in food industry). In an effort to gain more information on E12, its main constituents were formulated into two third generation formulations designated G1 and G2—effectively E12 with two SDS concentrations. In addition, another independent formulation was tested in this batch called G3.
[0000]
Antimicrobial effect of G formulations against indicator species.
NEAT
10 −1
10 −2
10 −3
10 −4
10 −5
Escherichia coli
Control
TNTC
TNTC
TNTC
>117
11
0
G1
1
TNTC
>96
>120
0
0
G2
9
68
22
1
0
0
G3
42
>70
0
0
0
0
Salmonella typhimurium
Control
TNTC
TNTC
TNTC
≅280
54
0
G1
4
TNTC
112
14
2
0
G2
0
98
60
6
0
0
G3
1
0
0
0
0
0
Staphylococcus aureus
Control
TNTC
TNTC
268
41
8 c
1
G1
≅350
119
19
0
0
0
G2
TNTC
333
40
14
1
0
G3
0
0
0
0
0
0
Pseudomonas aeruginosa
Control
TNTC
TNTC
80
30
1
1
G1
0
0
0
0
0
0
G2
0
0
0
0
0
0
G3
0
0
0
0
0
0
Listeria monocytogenes
Control
TNTC c
TNTC
TNTC c
115
18
1
G3
0 c
0
0
0
0
0
Enterococcus hirea
Control
TNTC
TNTC
TNTC
91
17
0
G1
97
9
0
0
0
0
G2
5
0
0
0
0
0
G3
0
26
0
0
0
0
Campylobacter jejuni
Control
TNTC
TNTC
TNTC
102 c
13
4
G3
0
0
0 c
0 c
0 c
0
Conclusion:
[0115] G1 and G2 were shown to be less effective than their parent compound E12. G1 reduced bacterial population by 1 Log unit and G2 by 2 Log units against E. coli and S. typhimurium respectively. The E12 antibacterial effect is superior to that of G1 and G2 combined. This pattern was also observed against E. hirae . However, G1 and G2 were very efficient against P. aeruginosa giving a 6 Log order reduction. They may be recommended for P. aeruginosa specific applications and could lead to expanded product applications and lower cost in production.
Test Report University College Dublin (UCD)
[0116] A sample of E12/C-Activ-12 formulated with other substances was tested on two strains of C. Jejuni in University College Dublin (UCD), using designated high throughput screening technology (HTS). 96 well plates were used to test a range of biocides against two strains of Campylobacter jejuni (strain NCTC 11168, other wildtype isolated from a poultry sample). A 1% v/v solution (in sterile distilled water) of the biocide was considered to be the working concentration. A range of the concentrations were prepared representing 200, 100, 50, 10, 1, 0.1 and 0.01% of the 1% biocide working solution and added to a 96 well plate. Overnight bacterial suspensions diluted to give an inoculum of approx 10 5 CFU per well were added to the 96 well plate. All strains were repeated in triplicate. The plate was incubated in microanaerobic conditions for 24 h at 37° C. A 96 pin replicator was then used to transfer a sample from the test wells to a 96 well plate filled with mCCDA. The mCCDA plate was incubated in microanaerobic conditions for 24 h at 37° C. and examined for growth. Results were recorded in wells where growth was observed. In all cases the biocidal activity of C-Activ-12 is maintained and is not inhibited. This is a significant qualification of the invention as it can be formulated with delivery technologies dependent on application. Conclusions: No cell growth was observed in any of the biocides when used at a 1% and 0.5%. There was no difference observed between the ability of the type or wildtype strain in surviving biocide exposure.
Conclusions: C-Activ-12 Maintains its Biocidal Activity.
[0117] No cell growth was observed in any of the biocides when used at a 1% and 0.5%. There was no difference observed between the ability of the type or wildtype strain in surviving biocide exposure.
[0000]
Activity of Working Solution C-Activ-12 with Ethanol, Surfactants & Other Available Technologies
E12
E12 + (1)
E12 ++ (1)
%
Rep 1
Rep 2
Rep 3
MIC
%
Rep 1
Rep 2
Rep 3
MIC
%
Rep 1
Rep 2
Rep 3
MIC
A
200
−
−
−
0
A
200
−
−
−
0
A
200
−
−
−
0
B
100
−
−
−
0
B
100
−
−
−
0
B
100
−
−
−
0
C
50
−
−
−
0
50
C
50
−
−
−
0
50
C
50
−
−
−
0
50
D
25
+
+
+
3
D
25
−
+
−
1
D
25
+
+
−
2
E
10
+
+
+
3
E
10
+
+
+
3
E
10
+
+
+
3
F
1
+
+
+
3
F
1
+
+
+
3
1
F
1
+
+
+
3
G
0.1
+
+
+
3
G
0.1
+
+
+
3
G
0.1
+
+
+
3
H
0
+
+
+
0
H
0
+
+
+
0
H
0
+
+
+
0
MIC of C-Activ-12 biocide against the Campylobacter jejuni type strain NCTC 11168
E12 (1)
E12 + (1)
E12 ++ (1)
%
Rep 1
Rep 2
Rep 3
MIC
%
Rep 1
Rep 2
Rep 3
MIC
%
Rep 1
Rep 2
Rep 3
MIC
A
200
−
−
−
0
A
200
−
−
−
0
A
200
−
−
−
0
B
100
−
−
−
0
B
100
−
−
−
0
B
100
−
−
−
0
C
50
−
−
−
0
50
C
50
−
−
−
0
50
C
50
−
−
−
0
50
D
25
+
+
+
3
D
25
−
+
−
1
D
25
+
+
−
2
E
10
+
+
+
3
E
10
+
+
+
3
E
10
+
+
+
3
F
1
+
+
+
3
F
1
+
+
+
3
1
F
1
+
+
+
3
G
0.1
+
+
+
3
G
0.1
+
+
+
3
G
0.1
+
+
+
3
H
0
+
+
+
0
H
0
+
+
+
0
H
0
+
+
+
0
Formulation of C-Activ-12 with SDS a Surfactant Technology
E12 (1)
E12 + (1)
E12 ++ (1)
%
Rep 1
Rep 2
Rep 3
MIC
%
Rep 1
Rep 2
Rep 3
MIC
%
Rep 1
Rep 2
Rep 3
MIC
A
200
−
−
−
0
A
200
−
−
−
0
A
200
−
−
−
0
B
100
−
−
−
0
B
100
−
−
−
0
B
100
−
−
−
0
C
50
−
−
−
0
50
C
50
−
−
−
0
50
C
50
−
−
−
0
50
D
25
+
+
+
3
D
25
+
+
+
3
D
25
+
+
+
3
E
10
+
+
+
3
E
10
+
+
+
3
E
10
+
+
+
3
F
1
+
+
+
3
F
1
+
+
+
3
1
F
1
+
+
+
3
G
0.1
+
+
+
3
G
0.1
+
+
+
3
G
0.1
+
+
+
3
H
0
+
+
+
0
H
0
+
+
+
0
H
0
+
+
+
0
MICs for biocides against the Campylobacter jejuni strain 1135 when formulated with Ethanol
E125 (1)
E125 + (1)
%
Rep 1
Rep 2
Rep 3
MIC
%
Rep 1
Rep 2
Rep 3
MIC
200
−
−
−
0
A
200
−
−
−
0
100
−
−
−
0
B
100
−
−
−
0
50
−
−
−
0
50
C
50
−
−
−
0
50
25
+
+
+
3
D
25
+
+
+
3
10
+
+
+
3
E
10
+
+
+
3
1
+
+
+
3
F
1
+
+
+
3
0.1
+
+
+
3
G
0.1
+
+
+
3
Formulation Factors—
[0118] The active phytochemical concentration of NF is 5% (w/w) and C-activ-12 is 0.5% (w/w), and therefore a 1% working solution implies a phytochemical concentration of 0.005% (v/v) and a 0.5% solution implies a phytochemical concentration of 0.0025% (v/v). However, these values assume that the flavanol phytochemical content is 100% pure. For all antimicrobial test assays, a working solution was subject to further sequential dilutions and exposed to a fixed bacterial cell population in a given volume for a fixed and reproducible time. The exposed mixing stage results in a final operational dilution of the product—final concentration is 8 parts formulation to 2 parts interfering substance and bacterial population, implying a further one fifth dilution, e.g. 0.5% (w/v) is at a final concentration of 0.4% (w/v) in the assay.
[0000]
Summary of phase 1 BS EN 1276 results in context of final working concentration of C-Activ-12
expressed in % (v/v) (Athlone Institue of Technology - Centre of Biopolymer & Biomolecular
Research and Department of Life & Physical Sciences - 2009 to 2011)
Test Bacteria
C-activ-12
Final
Campylobacter
Escherichia
Salmonella
Staphylococcus
Pseudomonas
Enterococcus
Listeria
% (v/v)*
% (v/v)
jejuni
coli
typhimurium
aureus
aeruginosa
hirae
monocytogenes
0
0
>1 × 10 8
>1 × 10 8
>1 × 10 8
>1 × 10 8
>1 × 10 8
>1 × 10 8
>1 × 10 8
0.5
0.4
>6 log
>5 log
>6 log
>5 log
>6 log
>5 log
>5 log
0.33
0.264
>6 log
>6 log
>1 log
>6 log
>5 log
>1 log
0.25
0.2
>6 log
>6 log
>6 log
>4 log
0.165
0.132
>6 log
>6 log
>6 log
>1 log
0.125
0.1
>6 log
>3 log
>6 log
>1 log
0.1
0.08
>6 log
<1 log
>3 log
>6 log
>1 log
0.05
0.04
>6 log
>1 log
>6 log
0.025
0.02
>5 log
>6 log
British European Standards Specification - BS EN EN 1276: 1997: Chemical disinfectants and antiseptics. Quantitative suspension test for the evaluation of bactericidal activity of chemical disinfectants and antiseptics used in food, industrial, domestic and institutional areas. Test methods and requirements without mechanical action. A log 5 reduction meets requirements for biocides, C-Activ-NF & C-Activ-12 surpass the required log reductions.
[0119] A comparison of comparative MIC values for different antimicrobial tests relative to common final working concentration of C-activ-12 expressed as a % dilution. Stock NF and C-activ-12 are prepared on a w/w basis, but subsequent dilutions are w/v and v/v, is shown below.
[0000]
Summary of C-activ-12 MIC Values and Susceptibility (UCD FIRM Study 2009-2012 & AIT Study 2009-2011)
MIC
Gram
Isolate
High-through put screening * (%)
Organism
Status
identifier
BS EN 1276 * (%)
Planktonic
Surface-dried
Biofilm
Campylobacter
\ C. jejuni
−ve
NCTC 11392
0.5
C. jejuni
−ve
NCTC 11168
0.5
0.5
0.5
C. jejuni
−ve
NCTC 1135
0.5
0.5
0.5
C. jejuni
−ve
Se 2
0.5
0.5
0.5
C. jejuni
−ve
Se 5
0.5
0.5
0.5
C. jejuni
−ve
Se 19
0.5
0.5
0.5
C. jejuni
−ve
Se 43
0.5
0.5
0.5
C. coli
−ve
Se 46
0.5
0.5
0.5
C. coli
−ve
Se 50
0.5
0.5
0.5
C. coli
−ve
Se 54
0.0001
0.0001
0.0001
C. jejuni
−ve
Se 77
0.5
0.5
0.5
C. jejuni
−ve
Se 83
0.5
0.5
0.5
C. jejuni
−ve
Se 84
0.1
0.1
0.1
C. jejuni
−ve
Se 85
0.5
0.5
0.5
C. jejuni
−ve
Se 86
0.5
0.5
0.5
C. jejuni
−ve
Se 96
0.5
0.5
0.5
C. coli
−ve
Se 185
0.5
0.5
0.5
C. jejuni
−ve
Se 226
0.5
0.5
0.5
C. coli
−ve
Se 241
0.5
0.5
0.5
C. coli
−ve
Se 246
0.5
0.5
0.5
C. coli
−ve
Se 266
0.5
0.5
0.5
C. coli
−ve
Se 279
0.5
0.5
0.5
C. coli
−ve
Se 311
0.5
0.5
0.5
C. coli
−ve
Se 316
0.5
0.5
0.5
C. coli
−ve
Se 330
0.5
0.5
0.5
C. jejuni
−ve
Se 341
0.5
0.5
0.5
C. jejuni
−ve
Se 366
0.5
0.5
0.5
C. jejuni
−ve
Se 376
0.5
0.5
0.5
Salmonella
S. typhimurium
−ve
ATCC 14028
0.165
Hadar
−ve
s6
0.1
0.5
3.13
Anatum
−ve
c28
0.2
0.25
3.13
Java
−ve
s43
0.2
0.5
6.25
Infantis
−ve
c9
0.2
0.5
3.13
S. typhimurium
−ve
s13
0.2
0.25
3.13
Dublin
−ve
s20
0.2
0.25
6.25
Anatum
−ve
c53
0.2
0.5
3.13
S. typhimurium
−ve
SL1344
0.2
0.5
1.56
Cronobacter
C. sakazakii
−ve
E543
0.2
0.5
6.25
C. turicensis
−ve
E866
0.2
0.25
0.39
C. sakazakii
−ve
E473
0.2
>0.5
3.13
C. sakazakii
−ve
E491
0.2
0.5
3.13
C. sakazakii
−ve
Baa
0.2
0.5
3.13
C. dublinensis
−ve
E515
0.2
0.5
1.56
C. sakazakii
−ve
E516
0.2
0.5
3.13
C. turicensis
−ve
E625
0.2
0.5
6.25
Pseudomonas
P. aeruginosa
−ve
ATCC 15442
0.025
P. aeruginosa
−ve
ATCC 15442
1.56
P. aeruginosa
−ve
ATCC 27853
2
0.78
<0.78
Escherichia
E. coli
−ve
ATCC 10539
2.0
0.19
E. coli
−ve
ATCC 25922
0.5
E. coli
−ve
ATCC 32518
0.05
0.39
Staphylococcus
S. aureus
−ve
ATCC 25923
0.5
S. aureus
+ve
ATCC 6538
2
0.02
S. aureus
+ve
ATCC 27853
0.025
0.39
Enterococcus
E. hirea
+ve
ATCC 8048
0.33
E. hirea
+ve
ATCC 10541
2
1.56
Listeria
L. monocytogenes
+ve
NCTC 11994
0.5
Summary of mean MIC values and susceptibility testing technique for bacteria tested
MIC
High-through put screening *
Organism
Gram Status
BS EN 1276 *
Planktonic
Surface-dried
Biofilm
Campylobacter
C. jejuni
−ve
0.5%
0.5%
0.5%
C. coli
−ve
0.5%
Salmonella
Hadar
0.1
0.5
3.13
Anatum
0.2
0.25
3.13
Java
0.2
0.5
6.25
Infantis
0.2
0.5
3.13
Typhimurium
0.2
0.25
3.13
Dublin
0.2
0.25
6.25
Anatum
0.2
0.5
3.13
Typhimurium
0.2
0.5
1.56
Cronobacter
C. sakazakii
−ve
0.2
0.5
3.45
C. dublinensis
−ve
0.2
0.5
1.56
C. turicensis
−ve
0.2
0.5
4.69
Pseudomonas
P. aeruginosa
−ve
2%
1.17
<0.78
Escherichia
E. coli
−ve
2%
0.19%
0.05
0.39
Staphylococcus
S. aureus
+ve
2%
0.022
0.39
Enterococcus
E. hirea
+ve
2
1.56
# cell density, 12 hr exposure,
* not accredited;
MIC - accepted ≧5 log reduction;
Representative test data, of which Table ?? is a summary is listed and concluded from p to p.
[0000]
Evaluation of Bactericidal Efficacy of Biocidal Compositions of the Invention Tested in
Accordance with BSEN 1276 (Test Report Athlone Institute of Technology - May 2009)
Bactericidal Activity Testing
Sample:
E12 Formulation (Brand name - C-Activ-12);
Batch Number:
E12May09
Manufacturer:
CeBeC Group Ltd.
Delivery Date:
8 th May 09
Product Storage:
5° C. in the dark.
Active Substance:
Confidential
Analysis Required:
BSEN 1276 Dilution/Neutralization under dirty conditions.
Experimental Conditions:
Product Diluent used during test:
Sterile hard water 300 mg/kg CaCO 3
Product Test Concentration:
5, 10, 20, 33.3, 50, 66.7 and 100% (v/v) (MIC assessment)
Contact Time:
5 min
Test Temperature:
20° C. ± 0.5° C.
Interfering Substance:
3.0 g/L Bovine albumin
Neutralising Solution:
3% Tween 80, 3% Saponin, 0.1% Histidine, 0.1% Cysteine
GRAM NEG
1. Bacterial Strains: Campylobacter jejuni NCTC 11392; Temperature of Incubation:
42° C. for 72 hours
2. Bacterial Strains: Escherichia coli ATCC 25922; Temperature of Incubation:
37° C. for 24 hours
3. Bacterial Strains: Salmonella typhimurium ATCC 14028; Temperature of Incubation:
37° C. for 24 hours
4. Bacterial Strains: Pseudomonas aeruginosa ATCC 15442; Temperature of Incubation:
37° C. for 24 hours
GRAM POS
5. Bacterial Strains: Staphylococcus aureus ATCC 25923; Temperature of Incubation:
37° C. for 24 hours
6. Bacterial Strains: Enterococcus hirae ATCC 8048; Temperature of Incubation:
37° C. for 24 hours
7. Bacterial Strains: Listeria monocytogenes ; Temperature of Incubation: 37° C. for 24 hours
NOTE:
BSEN 1276 requires 1 ml of the neutralised test mixture to be overlaid with 12-15 ml of the appropriate molten agar. However, because Blood Agar Base 2 contains sterile defibrinated horse blood it is impossible to keep it molten, as the blood proteins coagulate in the oven and fall out of solution. Hence, the plates were pre-poured & the sample volume was adjusted to 100 μl as per standard spread plate method.
NOTE:
Cells shaded yellow indicate the lowest concentration which induces a ~6 log order reduction (or greater) in bacterial viability.
NOTE:
E12 is commercially referred to as CeBeC “C-Activ-12” Natural Sanitiser
NOTE:
100% (v/v) represents 0.5% base dilution
Conclusions—1.
[0120] According to BSEN 1276, E12 is extremely effective in reducing the viability of this strain of Campylobacter jejuni under dirty conditions. Almost a total kill was evident at all E12 dilutions down to 10% v/v solution or 0.1% MIC. However, a 5 log order reduction was still observed at the 5% v/v level or 0.05% MIC, indicating that the minimum inhibitory concentration (MIC) for E12 on C. jejuni is at 0.5% v/v or slightly lower. 2. According to BSEN 1276, E12 is effective in reducing the viability of this strain of Escherichia coli under dirty conditions. There was a greater than 6 log reduction in bacterial viability at a concentration at 100% test concentration of E12 as provided blindly to lab technician at a 2% V/V dilution of C-Activ-12/E12. There was a significant reduction in bacterial viability counts at the more dilute concentrations. 3. According to BSEN 1276, E12 is effective in reducing the viability of this strain of Salmonella typhimurium under dirty conditions. There was a greater than 6 log reduction in bacterial viability at a concentration of 33.33% v/v of the E12 test concentration as provided to the lab technician at a blind working concentration of 2%. There was a slight reduction in bacterial viability counts at the more dilute concentrations. 4. According to BSEN 1276, E12 is extremely effective in reducing the viability of this strain of Pseudomonas aeruginosa under dirty conditions. A reduction of greater than 6 log order was observed down to a 5% v/v dilution of the E12 solution. Therefore, the MIC for this strain of bacteria is ≦5% v/v of the test concentration provided. There was a greater than 6 log reduction in bacterial viability at a concentration of 5% v/v of the E12 test concentration as provided to the lab technician at a blind working concentration of 2%. 5. According to BSEN 1276, E12 is effective in reducing the viability of this strain of Staphylococcus aureus under dirty conditions. There was a greater than 5 log reduction in bacterial viability at a concentration of 100% v/v of the E12 test concentration as provided to the lab technician at a blind working concentration of 2%. There was a slight reduction in bacterial viability counts at the more dilute concentrations. 6. According to BSEN 1276, E12 is extremely effective in reducing the viability of this strain of Enterococcus hirae under dirty conditions. A reduction of 5 order log reduction was observed in bacterial viability at a concentration of 66.67% v/v of the E12 test concentration as provided to the lab technician at a blind working concentration of 2% v/v E12 solution, making 1% the MIC value for this strain of bacteria. There was a slight reduction in viability counts at the more dilute concentration. 7. According to BSEN 1276, E12, at 100% (v/v) is effective in reducing the viability of this strain of Listeria monocytogenes under dirty conditions. The results show an almost complete kill with the Neat solution. However, further dilutions of the E12 solution showed a slightly reduced viability, but not the required 5 log reduction.
[0000]
Test Results, BSEN 1276, C. Jejuni - Athlone Institue of Technology May 2009
Bacterial Dilution
Neat
10 −1
10 −2
10 −3
10 −4
10 −5
10 −6
10 −7
Untreated
>3 × 10 3
>3 × 10 3
>3 × 10 3
V c > 10
V c 3
V c 0
V c 0
V c 0
control
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
E12 Conc.
% (v/v)
100
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
66.7
V c 0
V c 0
V c 0
V c 0
V c 2
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
50
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
33
V c 0
V c 0
V c 0
V c > 1
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
25
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
20
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
10
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
5
2.29 × 10 3
2.0 × 10 2
V c 3
V c 0
V c 1
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
Vc = viable count;
Na = number of cfu/ml in the test mixture
NOTE:
The BSEN 1276 standard dictates that colony counts of less than 15 are represented by <1.5 × 10 2 and that counts of over 300 be presented as >3 × 10 3
Summary threshold
Test Results BSEN
Summary threshold
results, C. jejuni
1276, E. Coli
results, S. typhimurium
E12 Blind
Reduction in
E12 Concen-
Reduction in
E12 Concen-
Test
Viability
tration %
Viability
tration
Reduction in
0
>1 × 10 8
0
>1 × 10 8
0
>1 × 10 8
100%
>6 log
100
>6 log
100
>6 log
66.67
>6 log
66.67
≧3 log
66.67
>6 log
50
>6 log
50
>2 log
50
>6 log
33.33
>6 log
33.33
>2 log
33.33
>6 log
25
>6 log
25
<1 log
25
>3 log
20
>6 log
20
<1 log
20
>3 log
10
>6 log
10
<1 log
10
>1 log
5
>5 log
5
<1 log
5
—
Summary threshold results, E. coli
Bacterial Dilution
Neat
10 −1
10 −2
10 −3
10 −4
10 −5
10 −6
10 −7
E12 Conc.
% (v/v)
100
V c 0
V c 5
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
50
V c > 300
V c > 300
V c > 300
V c 131
V c 4
V c 0
V c 0
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.31 × 10 5
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
33
V c > 300
V c > 300
V c > 300
V c > 300
V c 40
V c 0
V c 0
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 4.0 × 10 5
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
25
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c 52
V c 1
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 5.2 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
20
V c > 300
V c > 300
V c > 300
V c > 300
V c 46
V c 7
V c 1
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 4.6 × 10 5
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
10
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c 65
V c 4
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 6.5 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
5
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c 68
V c 4
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 6.8 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
Vc = viable count
Na = number of cfu/ml in the test mixture
NOTE:
The BSEN 1276 standard dictates that colony counts of less than 15 are represented by <1.5 × 10 2 and that counts of over 300 be presented as >3 × 10 3 .
Test Results BSEN 1276 S. Typhimurium
Bacterial Dilution
Neat
10 −1
10 −2
10 −3
10 −4
10 −5
10 −6
10 −7
Untreated
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c 30
V c 5
V c 3
control
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 3.0 × 10 6
Na < 1.5 × 10 2
Na < 1.5 × 10 2
E12 Conc.
% (v/v)
100
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
66.7
V c 0
V c 2
V c 1
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
50
V c 0
V c 0
V c 0
V c 0
V c 0
V c 1
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
33
V c 1
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
25
V c 17
V c 118
V c 51
V c 3
V c 0
V c 0
V c 0
V c 0
N a 1.7 × 10 1
N a 1.18 × 10 3
N a 5.1 × 10 3
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
20
V c > 300
V c > 300
V c 67
V c 7
V c 0
V c 1
V c 0
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a 6.7 × 10 3
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
10
V c > 300
V c > 300
V c > 300
V c > 300
V c 199
V c 21
V c 1
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.99×10 6
N a 2.1 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
Vc = viable count
Na = number of cfu/ml in the test mixture
NOTE:
The BSEN 1276 standard dictates that colony counts of less than 15 are represented by <1.5 × 10 2 and that counts of over 300 be presented as >3 × 10 3 .
Test Results BSEN 1276, P. Aeruginosa
Bacterial Dilution
Neat
10 −1
10 −2
10 −3
10 −4
10 −5
10 −6
10 −7
Untreated
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c > 221
V c 24
V c 3
control
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 2.21 × 10 6
N a 2.4 × 10 2
N a < 1.5 × 10 2
E12
Concentration
% (v/v)
100
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
66.7
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
50
V c 0
V c 2
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
33
V c 2
V c 1
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
25
V c 0
V c 0
V c 0
V c 1
V c 0
V c 0
V c 1
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
20
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
10
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
5
V c 6
V c 5
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
Vc = viable count
Na = number of cfu/ml in the test mixture
NOTE:
The BSEN 1276 standard dictates that colony counts of less than 15 are represented by <1.5 × 10 2 and that counts of over 300 be presented as >3 × 10 3 .
Test Results BSEN 1276, S. aureus
Bacterial Dilution
Neat
10 −1
10 −2
10 −3
10 −4
10 −5
10 −6
10 −7
Untreated
V c > 300
V c > 300
V c > 300
V c > 300
V c 174
V c 18
V c 2
V c 0
control
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.74 × 10 6
N a 1.8 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
E12
Concentration
% (v/v)
100
V c 0
V c 10
V c 5
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
66.7
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c 114
V c 47
V c 4
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.14 × 10 7
N a 4.7 × 10 7
N a < 1.5 × 10 2
50
V c > 300
V c > 300
V c 280
V c 32
V c 4
V c 1
V c 1
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a 2.8 × 10 4
N a 3.2 × 10 4
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
33
V c > 300
V c > 300
V c > 300
V c 277
V c 86
V c 19
V c 12
V c 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 2.77 × 10 5
N a 8.6 × 10 5
N a 1.9 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
25
V c > 300
V c > 300
V c > 300
V c > 300
V c 39
V c 12
V c 5
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 3.93 × 10 5
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
20
V c > 300
V c > 300
V c > 300
V c 137
V c 23
V c 6
V c 4
V c 1
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.37 × 10 5
N a 2.3 × 10 5
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
10
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c 146
V c 87
V c 12
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.46 × 10 7
N a 8.7 × 10 7
N a < 1.5 × 10 2
5
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c 70
V c 21
V c 2
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 7.0 × 10 6
N a 2.1 × 10 7
N a < 1.5 × 10 2
Vc = viable count
Na = number of cfu/ml in the test mixture;
NOTE:
The BSEN 1276 standard dictates that colony counts of less than 15; are represented by <1.5 × 10 2 and that counts of over 300 be presented as >3 × 10 3 .
Summary threshold results, P. aeruginosa
Summary threshold results, S. aureus
E12
E12
Concentration
Reduction in Viability of
Concentration
Reduction in Viability of
% (v/v)
Pseudomonas aeruginosa
% (v/v)
Staphylococcus aureus
0
>1 × 10 8
0
>1 × 10 8
100
>6 log
100
>5 log
66.67
>6 log
66.67
>1 log
50
>6 log
50
—
33.33
>6 log
33.33
—
25
>6 log
25
—
20
>6 log
20
—
10
>6 log
10
—
5
>6 log
5
—
Test Results BSEN 1276, E. hirae
Bacterial Dilution
Neat
10 −1
10 −2
10 −3
10 −4
10 −5
10 −6
10 −7
Untreated
V c > 300
V c > 300
V c > 300
V c > 300
V c 152
V c 19
V c 3
V c 0
control
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.52 × 10 5
N a 1.9 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
E12
Concentration
% (v/v)
100
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
V c 0
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
66.7
V c 27
V c > 23
V c 1
V c 0
V c 0
V c 1
V c 0
V c 0
N a 2.7 × 10 1
N a > 2.3 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
50
V c 111
V c 92
V c 18
V c 1
V c 0
V c 0
V c 0
V c 0
N a 1.11 × 10 2
N a 9.2 × 10 2
N a 1.8 × 10 3
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
33
V c > 300
V c > 300
V c > 300
V c 32
V c 5
V c 1
V c 0
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 3.2 × 10 4
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
25
V c > 300
V c > 300
V c > 300
V c 56
V c 1
V c 0
V c 0
V c 1
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 5.6 × 10 4
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
20
V c > 300
V c > 300
V c > 300
V c 90
V c 12
V c 3
V c 0
V c 1
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 9.0 × 10 4
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
10
V c > 300
V c > 300
V c > 300
V c > 300
V c 34
V c 3
V c 1
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 3.4 × 10 5
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
5
V c > 300
V c > 300
V c > 300
V c > 300
V c 124
V c 13
V c 2
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.24 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
Vc = viable count
Na = number of cfu/ml in the test mixture
NOTE:
The BSEN 1276 standard dictates that colony counts of less than 15 are represented by <1.5 × 10 2 and that counts of over 300 be presented as >3 × 10 3 .
Summary threshold results, E. hirae
E12
Reduction in
Concentration
Viability of
% (v/v)
Enterococcus hirae
0
>1 × 10 8
100
>5 log
66.67
>5 log
50
>4 log
33.33
>1 log
25
>1 log
20
>1 log
10
—
5
—
Test Results BSEN 1276, L. Monocytogenes
Bacterial Dilution
Neat
10 −1
10 −2
10 −3
10 −4
10 −5
10 −6
10 −7
Untreated
V c > 300
V c > 300
V c > 300
V c > 300
V c 289
V c 35
V c 4
V c 1
control
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 2.89 × 10 6
N a 3.5 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
E12 Conc.
% (v/v)
100
V c 0
V c 1
V c 0
V c 0
V c 0
V c 0
V c 0
V c 1
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
66.7
V c > 300
V c > 300
V c > 300
V c > 300
V c 97
V c 6
V c 0
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 9.7 × 10 5
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
50
V c > 300
V c > 300
V c > 300
V c 74
V c 2
V c 1
V c 0
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 7.4 × 10 4
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
33
V c > 300
V c > 300
V c > 300
V c > 300
V c 143
V c 15
V c 2
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.43 × 10 6
N a 1.5 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
25
V c > 300
V c > 300
V c > 300
V c > 300
V c 179
V c 14
V c 4
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 1.79 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
20
V c > 300
V c > 300
V c > 300
V c > 300
V c 252
V c 24
V c 0
V c 1
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 2.52 × 10 6
N a 2.4 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
10
V c > 300
V c > 300
V c > 300
V c > 300
V c 327
V c 14
V c 2
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 3.27 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
N a < 1.5 × 10 2
5
V c > 300
V c > 300
V c > 300
V c > 300
V c > 300
V c 30
V c 6
V c 0
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a > 3 × 10 3
N a 3.0 × 10 6
N a < 1.5 × 10 2
N a < 1.5 × 10 2
Vc = viable count
Na = number of cfu/ml in the test mixture
NOTE:
The BSEN 1276 standard dictates that colony counts of less than 15 are represented by <1.5 × 10 2 and that counts of over 300 be presented as >3 × 10 3 .
Summary threshold results, L. monocytogenes
E12
Reduction in
Conc
Viability of
% (v/v)
Listeria monocytogenes
0
>1 × 10 8
100
>5 log
66.67
>1 log
50
—
33.33
—
25
—
20
—
10
—
5
—
Gram Negative versus Gram Positive Results
Bacteria
E12
Gram Negative
Gram Positive
Concentration
Campylobacter
Escherichia
Salmonella
Pseudomonas
Staphylococcus
Enterococcus
Listeria
% (v/v)*
jejuni
coli
typhimurium
aeruginosa
aureus
hirae
monocytogenes
0
>1 × 10 8
>1 × 10 8
>1 × 10 8
>1 × 10 8
>1 × 10 8
>1 × 10 8
>1 × 10 8
100
>6 log
>6 log
>6 log
>6 log
>5 log
>5 log
>5 log
66.67
>6 log
≧3 log
>6 log
>6 log
>1 log
>5 log
>1 log
50
>6 log
>2 log
>6 log
>6 log
>4 log
33.33
>6 log
>2 log
>6 log
>6 log
>1 log
25
>6 log
<1 log
>3 log
>6 log
>1 log
20
>6 log
<1 log
>3 log
>6 log
>1 log
10
>6 log
<1 log
>1 log
>6 log
5
>5 log
<1 log
>6 log
NOTE:
Cells shaded yellow indicate the lowest concentration which induces a ~6 log order reduction (or greater) in bacterial viability.
NOTE:
E12 is commercially referred to as CeBeC “C-Activ-12” Natural Sanitiser
NOTE:
100% (v/v) represents 0.5% base dilution
Summary of Log Reduction Threshold Expressed in Terms of C-Activ-12 Concentration
[0121] The current formulation is therefore effective at a 5 log reduction level against all seven test organisms (designated strains) at a MIC concentration of 0.5% (v/v). Due to the presence of non-flavonoid natural compounds in the sourced complex, the final pure flavonoid concentration is ˜0.25% (v/v).
Efficacy Testing of CeBeC Natural Biocides Against Planktonic Campylobacter and Campylobacter Isolates in Bio-Films—University College Dublin Dr Stephen O'Brien
[0122] 96 well plates were used to test a range of CeBeC Natural biocides against Campylobacter jejuni Type strain NCTC 11168 and Wild Type Campylobacter jejuni (isolated from a poultry sample). All biocides were tested at a range of concentrations. Where a range of working concentrations were given, the highest recommended concentration was considered the 100% working concentration. For example, if the working was recommended for use at 0.5-1%, a 1% v/v solution in sterile water was considered the 100% working concentration. A range of concentrations were prepared representing 200, 100, 50, 10, 1, 0.1 and 0.01% of the biocides working concentration and added to a 96 well plate. The plates were incubated micro-aerobically for 24 h at 41.5° C. A pin replicator was then used to transfer samples from each well to a 96 well plate filled mCCDA agar. The mCCDA plates were incubated microaerobically at 41.5° C. for 24 h and examined for growth. All strains were repeated in triplicate. The Campylobacter jejuni strains were also tested in a biofilm. This was achieved by adding overnight cultures to the 96 well plate and incubating them at 41.5° C. for 24 h. The media was carefully removed from the each well and replaced with 100 μl of fresh media again followed by incubation at 41.5° C. for 24 hours. This process was repeated a total of 3 times. The formation of a biofilm was confirmed using a Crystall Violet assay. The biofilms were then tested with the various biocide concentrations as described above. More detail on preparing the assay has been appended to the end of this document. Results were recorded for wells where growth was observed.
Results—
[0123] No cell growth was observed in any of the biocides when used in their recommended concentration ranges. There was no difference observed between the ability of the C. jejuni Type strain or Wild Type strain to surviving biocide exposure. All of the biocides were effective at their recommended working concentration on planktonic C. jejuni and those in a biofilm. The biocides were consistently effective at killing Log 10 5 CFU of C. jejuni when used at 50% of their recommended working concentration. The full results are presented in Table I, Table II, Table III and Table IV on pages 4 to 6 of this report.
Protocol for MIC of Biocides—
[0124] Inoculum Grow strains overnight (16-18 h) in 10 ml Mueller-Hinton broth with Campylobacter growth supplement at 41.5° C. with shaking (200 rpm). Strains should reach ≧10 9 CFU/ml. Dilute in Mueller-Hinton with Campylobacter growth supplement broth to give approx 10 7 CFU/ml. Add 100 ml of approx 10 7 CFU/ml to 10 ml double-strength (ds) Mueller-Hinton broth with Campylobacter growth supplement to give an inoculum of approx 10 5 CFU/ml (when 100 ml is added to each well in the plate the inoculum per well is approx 10 4 CFU).
Biocide
[0125] Determine the 100% working concentration of each biocide. Example—If the recommended working concentration is 0.5-1% of the concentrate provided (consider 100% working concentration to be 1% solution of the concentrate). Prepare double-strength solutions of the biocides in sterile distilled H 2 O (i.e. for 200% working concentration in the plate make a 400% working concentration solution). Example—If the working concentration is a 1% solution of the concentrate; prepare 4% solution of the concentrate for a 400% working concentration. If the sterility of the 400% working concentration may be in doubt (possible if using a detergent not a disinfectant) then filter sterilise before proceeding with the dilutions. Prepare dilutions of the biocides to give the final % working concentrations according to the screening plates (see table below). Example—to give enough of each concentration for approximately 50 plates (50 strains), given 100 μl in 3 wells per plate.
[0000]
For a working concentration of 1%
Sterile
For final
Prepare %
distilled
% working
working
H 2 O
concentration
concentration
Biocide
(ml)
200
400
1.6 ml Biocide concentrate
38.4
100
200
15 ml of 400% (above)
15.0
50
100
12 ml of 200% (above)
12.0
10
20
4 ml of 100% (above)
16.0
1
2
2 ml of 20% (above)
18.0
0.1
0.2
2 ml of 2% (above)
18.0
0.01
0.02
2 ml of 0.2% (above)
18.0
0
0
0
20.0
Screening Plates—
[0126] For all strains against all biocides use the final working concentrations below. Use multiple biocides per plate and one strain per plate (this is to reduce cross-contamination of strains). Use a minimum of N=3 per biocide. Add to 3 wells per row 100 ml of the % working concentrations
Incubation—
[0127] Add 100 μl inoculum at ˜10 5 CFU/ml to each well. Incubate plates microaerobically for 24 h at 41.5° C. Use a pin replicator to transfer samples from each well to a 96 well plate filled mCCDA agar. Incubate mCCDA plates were incubated microaerobically at 41.5° C. for 24 h and examined for growth. All strains were repeated in triplicate.
Results & Minimum Inhibitory Concentrations of Strains
[0128]
[0000] Strain C. jejuni NCTC 11168 Strain C. jejuni NCTC 11168 (Biofilm) E12 (1) CeBeC Natural Sanitiser % Rep 1 Rep 2 Rep 3 MIC % Rep 1 Rep 2 Rep 3 MIC A 200 − − − 0 A 200 − − − 0 B 100 − − − 0 B 100 − − − 0 C 50 − − − 0 50 C 50 − − − 0 50 D 25 + + + 3 D 25 + + + 3 E 10 + + + 3 E 10 + + + 3 F 1 + + + 3 F 1 + + + 3 G 0.1 + + + 3 G 0.1 + + + 3 H 0 + + + 0 H 0 + + + 0 Wild Type Strains - Isolated from Poultry Strain C. jejuni (Wild Type) 1135 Strain C. jejuni (Wild Type) 1135 (Biofilm) CeBeC Natural Sanitiser CeBeC Natural Sanitiser % Rep 1 Rep 2 Rep 3 MIC % Rep 1 Rep 2 Rep 3 MIC A 200 − − − 0 A 200 − − − 0 B 100 − − − 0 B 100 − − − 0 C 50 − − − 0 50 C 50 − − − 0 50 D 25 + + + 3 D 25 + + + 3 E 10 + + + 3 E 10 + + + 3 F 1 + + + 3 F 1 + + + 3 G 0.1 + + + 3 G 0.1 + + + 3 H 0 + + + 0 H 0 + + + 0
Epidemiology Study on Efficacy of CeBeC Natural Biocides Against Campylobacter Isolates from Irish Broiler Farms—Dr Emer O'Mahony University College Dublin
Tolerance—
[0129] Twenty-five Campylobacter isolates from Irish broiler farms and two reference strains were examined for tolerance to formulations of C-ACTIV-12, a commercial mixture of generally recognized as safe (GRAS) approved extracts. Isolate selection and growth conditions—Isolates were cultured and confirmed to the genus and species levels as previously described. The C. jejuni Type strain NCTC 11168 and a C. jejuni strain (denoted 1135) isolated from a poultry sample were also included. The isolate collection was stored at −80° C. on Protect cryobeads (Technical Service Consultants Ltd) containing 80% glycerol, for subsequent testing. When required, Campylobacter isolates were cultured from the frozen stock on Mueller-Hinton agar plates (MHA CM337, Oxoid) supplemented with 5% (v/v) lysed horse blood (TCS Biosciences), under microaerophilic conditions (10% CO 2 , 5% O 2 and 85% N 2 ) using a GENbox MicroAir (bioMérieux) at 37° C. for 24 h. Isolates were sub-cultured onto Columbia agar (Oxoid, UK), containing 5% (v/v) lysed horse blood, and incubated under microaerophilic conditions at 41.5° C. for 48 h. Biocide tolerance testing—Strains were grown under microaerophilic conditions overnight (16-18 h) in 5 ml Mueller Hinton broth (MHB, Oxoid) at 41.5° C. to reach approximately 10 7 CFU/ml. From this suspension, 100 μl was transferred into 10 ml double strength MHB (dsMHB) to give an inoculum of approximately 10 5 CFU/ml. A stock solution (4× recommended working concentration) of each biocide formulation was prepared. Dilutions (100 μl) of each formulation were prepared in triplicate using sterile distilled H 2 O in sterile 96-well plates (Sarstedt) and 100 μl of the (approximately) 10 5 CFU/ml inoculum was added to each well (giving a final inoculum of approximately 10 4 CFU/well). Plates were incubated microaerophilically for 24 h at 41.5° C. A 96 pin replicator (Nunc®) was used to transfer approximately 1 μl from each well to Campylobacter blood-free selective agar base (CCDA, CM0739, Oxoid), supplemented with CCDA selective supplement (SR0155, Oxoid) in 96 well plates. These plates were incubated microaerophilically for 24 h at 41.5° C. The minimum inhibitory concentration (MIC) was considered as the lowest concentration with no visible growth present. Results are shown below. Results—100% (n=27) of Campylobacter isolates studied were susceptible to all C-ACTIV-12 formulations at ≦100% of the recommended working concentration. 100% of Campylobacter isolates studied were susceptible to C-ACTIV-12 at ≦50% of the recommended working concentration.
[0000]
MICs of each formulation of the biocide C-ACTIV-12 1
Strain
Source
Species
C-ACTIV-12
Se 2
Breeder faeces
C. jejuni
50
Se 5
Breeder faeces
C. jejuni
50
Se 19
Breeder faeces
C. jejuni
50
Se 43
Breeder faeces
C. jejuni
50
Se 46
Breeder faeces
C. coli
50
Se 50
Breeder faeces
C. coli
50
Se 54
Breeder faeces
C. coli
0.01
Se 77
Broiler faeces
C. jejuni
50
Se 83
Adj broiler faeces
C. jejuni
50
Se 84
Adj broiler faeces
C. jejuni
10
Se 85
Adj broiler faeces
C. jejuni
50
Se 86
Adj broiler faeces
C. jejuni
50
Se 96
Broiler faeces
C. jejuni
50
Se 185
Breeder faeces
C. coli
50
Se 226
Broiler faeces
C. jejuni
50
Se 241
Breeder faeces
C. coli
50
Se 246
Breeder faeces
C. coli
50
Se 266
Breeder faeces
C. coli
50
Se 279
Breeder faeces
C. coli
50
Se 311
Breeder faeces
C. coli
50
Se 316
Breeder faeces
C. coli
50
Se 330
Breeder faeces
C. coli
50
Se 341
Breeder faeces
C. jejuni
50
Se 366
Broiler faeces
C. jejuni
50
Se 376
Broiler faeces
C. jejuni
50
1135
Poultry
C. jejuni
50
NCTC 11168
Human faeces
C. jejuni
50
Table Footnotes:
1 MIC is reported as % of recommended working concentration; =1% = 99 parts water plus 1 part C-ACTIV-12
Summary of Initial Findings—
[0130] In the early stages of these investigations, efforts were concentrated on two zoonotic pathogens namely verocytoxigenic Escherichia coli O157 and Salmonella species, along with the recently described powdered infant formula pathogen Cronobacter species. All isolates analysed (in each case >100 were selected from strains recovered during various epidemiological studies) were found to be susceptible to biocides in common use in the meat and PIF industries. Some of the genera appeared to be more susceptible compared with others, as in the case of Cronobacter . Attempts to develop tolerant phenotypes were marginally successful and where this was generated, the phenotype was unstable. As a means of modelling the increased tolerance to biocide-active compounds, a small number of isolates were challenged with increasing concentrations of actives such as triclosan, chlorhexidine and benzalkonium chloride. Highly-tolerant mutant phenotypes were obtained and these are currently being studied in detail, using a dedicated technical pipeline, described above. It was decided that it would be of interest to include the food-borne zoonotic pathogen Campylobacter and to evaluate its susceptibility/tolerance to the same panel compounds. Once again, it could be shown that Campylobacter was susceptible. However, as the panel of compounds used could be described as synthetic, the availability of C-Activ-12 presented the opportunity to re-evaluate the responses of these bacteria to this natural biocide. Initially planktonically-growing campylobacter were tested and found to be completely susceptible to C-Activ-12 at concentrations ranging from 0.5 through 1% (w/v). Similarly when these same cells were part of a biofilm, C-Active-12 remained effective over the latter concentration range. These studies were subsequently extended to include Cronobacter, Salmonella and E. coli (as outlined above) and in each case the bacteria tested were found to be susceptible to the natural biocide, being bacteriocidal in all cases. In the current project proposal, this inhibitory effect will be characterised in detail, to provide a means of understanding the mode of action. In this way it is envisaged that the C-Activ-12 compound can be modified to enhance its bacteriocidal effects on these and other pathogens (preliminary data suggests biocidal activity against, important clinical pathogens such as Acinetobacter baummanii and Clostridium difficile , along with a number of canine dental pathogens also). C-Activ-12 is a novel natural biocide. The formulation ingredients are FDA GRAS approved comprising organic acids and natural fruit extracted polyphenols. The broad spectrum activity of the formulation resulted it its inclusion in a University College Dublin Government funded independent study under the FIRM (see hereunder) research program. The program studies the effectiveness of products used to manage micro-organisms/pathogens prevalent in the food sector, comparing effectiveness & testing against isolated strains. To date CeBeC's C-Activ-12 has killed all organisms tested under FIRM, this study is on-going. The Irish Department of Agriculture and Food's Food Institutional Research Measure (FIRM) is funded under the National Development Plan 2007-2013. FIRM is the primary national funding mechanism for food research in third level colleges and research institutes. FIRM is a public good competitive programme whereby multi-disciplinary teams from two or more institutions usually carry out the research projects. Research outputs are communicated to industry by a dedicated dissemination team known as RELAY. FIRM aims to develop public good technologies that will underpin a competitive, innovative and sustainable food manufacturing and marketing sector. The programme is creating a base of knowledge and expertise in generic technologies that will support a modern, consumer-focused industry and build Ireland's capacity for R&D. A key output of the FIRM is highly trained young researchers at PhD and postdoctoral level, with specialist skills particularly relevant to the Irish food sector. The following pages provide an overview of the effectiveness of CeBeC's C-Activ-12 in killing micro-organisms. Standard testing protocols were first applied by AIT CBBR under British & European Food Grade Sanitiser Standard BS EN 1276, requiring a log 5 reduction from a log 7 to a log 2. The activity of C-Activ-12 highlighted a greater than log 6 reduction from a log 8. Based on the results under BS EN 1276, UCD added the product under the FIRM study whereby pathogens were isolated from food production environments. The rationale behind this approach is that most standards rely on ATCC & NCTC cultures which are more than often easier to kill than isolates. CeBeC's natural food based biocide has proven effective against strains isolated from growing & processing facilities and against strains isolated from humans. The following results provide an overview of efficacy under BS EN 1276 strains whilst providing more detail on activity against Pseudomonas .
[0000]
Comparison of Active Substances (Biocidal Compounds) UCD FIRM Study -
Sample size (n = 74). 74 strains involved in this screening.
Compounds
Unit
Stdev
Range
MIC
Eugenol
ul/ml
0.86
0.38
0.25-2
Benzoic Acid
ug/ml
810.51
398.91
247.5-1320
Trans-cinnaldeheyde
ul/ml
0.43
0.19
0.2-0.8
Cininamic Acid
ug/ml
95.12
44.09
23.44-140.65
a-Terpineol
ul/ml
2.43
1.64
0.53-7.59
Geraniol
ul/ml
8.29
4.50
0.94-15
Thymol
ug/ml
85.73
52.511
19.69-315
E12/C-Activ-12
ul/ml
2.92
1.21
0.625-10
MBC
Eugenol
ul/ml
0.99
0.33
0.25-2
Benzoic Acid
ug/ml
920.79
483.34
165-1320
Trans-cinnaldeheyde
ul/ml
0.50
0.29
0.05-0.8
Cininamic Acid
ug/ml
119.40
52.01
23.44-421.88
a-Terpineol
ul/ml
2.84
2.31
0.42-7.59
Geraniol
ul/ml
9.46
5.39
0.94-22.5
Thymol
ug/ml
121.38
66.39
4.92-315
E12/C-Activ-12
ul/ml
2.95
2.16
0.625-10
FIRM Study - Market Place Biocidal Product Comparative Effectiveness - E12 highlighted = C-Activ-12
MIC
Quadet
oxonia
Top
Labdet
MIC
Serotype
Antibiogram
E12
Divoshaum
clear
Byodet
Byosan
active
Triquart
Active
100
Salmonella
s6
Hadar
Tet, Cip, Fis,
0.1
25
6.25
0.78
0.78
3.13
6.25
3.13
25
Sxt, Str
c28
Anatum
Tet, Cip, Xnl,
0.2
12.5
3.13
0.2
0.39
1.56
6.25
1.56
1.56
Fis, Sxt, Str
s43
Java
Tet, Fis, Str
0.2
25
0.2
0.2
1.56
1.56
1.56
3.13
c9
Infantis
Cip, Fis, Sxt
0.2
50
6.25
0.39
0.39
3.13
6.25
3.13
12.5
s13
Typhimurium
Chl, Tet, Aug2,
0.2
3.13
1.56
0.2
0.2
1.56
1.56
1.56
1.56
Cip, Fis, Sxt
s20
Dublin
Cip, Sxt
0.2
50
3.13
0.2
0.2
1.56
3.13
3.13
50
c53
Anatum
Fox, Cip, Gen,
0.2
25
3.13
0.2
0.2
1.56
1.56
1.56
12.5
Nal, Xnl, Fis
ATCC SL1344
Typhimurium
0.2
Cronobacter
E543
C. sakazakii
Fis, Fox, Axo,
0.2
25
1.56
0.2
0.2
0.78
3.13
1.56
3.13
Gen, Cip, Xnl
E866
C. turicensis
Fis, Fox
0.2
6.25
0.78
0.2
0.2
0.78
0.78
1.56
6.25
E473
Fis, Fox, Nal,
0.2
50
1.56
0.2
0.2
1.56
3.13
1.56
25
Gen, Xnl
E491
Fis, Ami, Gen
0.2
25
3.13
0.2
0.2
0.78
1.56
1.56
12.5
Baa
C. sakazakii
Fis
0.2
50
3.13
0.2
0.2
3.13
6.255
3.13
25
E515
C. dublinensis
Fis, Xnl
0.2
50
1.56
0.2
0.2
0.78
1.56
1.56
25
E516
Fis, Fox, Xnl,
0.2
3.13
1.56
0.2
0.2
3.13
1.56
3.13
3.13
Cip, Nal, Ami,
E625
C. turicensis
Fis
0.2
25
0.78
0.2
0.2
0.78
1.56
0.78
3.13
MBC
Quadet
oxonia
Top
Labdet
MBC
Serotype
Antibiogram
E12
Divoshaum
clear
Byodet
Byosan
active
Active
Triquart
100
Salmonella
s6
Hadar
Tet, Cip, Fis,
0.1
50
6.25
1.56
0.78
3.13
12.5
3.13
25
Sxt, Str
c28
Anatum
Tet, Cip, Xnl,
0.2
3.13
3.13
0
0.39
1.56
3.13
1.56
3.13
Fis, Sxt, Str
s43
Java
Tet, Fis, Str
0.2
12.5
0.2
0.2
3.13
1.56
1.56
12.5
c9
Infantis
Cip, Fis, Sxt
0.2
50
1.56
0.39
0.39
1.56
1.56
0.78
12.5
s13
Typhimurium
Chl, Tet, Aug2,
0.2
25
1.56
0.2
0
1.56
1.56
1.56
50
Cip, Fis, Sxt
s20
Dublin
Cip, Sxt
0.2
50
3.13
0.2
0.2
0.78
0.78
1.56
50
c53
Anatum
Fox, Cip, Gen,
0.2
100
3.13
0
0.78
1.56
3.13
1.56
25
Nal, Xnl, Fis
ATCC SL1344
Typhimurium
0.2
Cronobacter
E543
C. sakazakii
Fis, Fox, Axo,
0.2
25
3.13
0.2
0.2
1.56
1.56
1.56
3.13
Gen, Cip, Xnl
E866
C. turicensis
Fis, Fox
0.2
6.25
0.78
0.2
0.2
0.78
0.78
0.78
6.25
E473
Fis, Fox, Nal,
0.2
50
1.56
0.2
0.2
1.56
3.13
1.56
25
Gen, Xnl
E491
Fis, Ami, Gen
0.2
25
3.13
0.2
0.2
1.56
1.56
1.56
25
Baa
C. sakazakii
Fis
0.2
50
3.13
0.2
0.39
6.25
3.13
3.13
25
E515
C. dublinensis
Fis, Xnl
0.2
12.5
1.56
0.2
0.2
0.78
1.56
1.56
6.25
E516
Fis, Fox, Xnl,
0.2
6.25
1.56
0.2
0.2
6.25
1.56
3.13
1.56
Cip, Nal, Ami,
E625
C. turicensis
Fis
0.2
25
0.78
0.2
0.2
0.78
1.56
0.78
6.25
Biofilm 60 min exposure
Quadet
Oxonia
Top
Labdet
E12
Divoshaum
clear
Byosan
active
Active
Triquart
100
Salmonella
SE 30
50
200
50
6.25
200
200
50
200
s6
25
c28
50
s43
50
c9
25
s25
25
s20
50
c53
50
ATCC 1344
>50
Cronobacter
E462
50
>200
50.00
6.25
>200
>200
>200
>200
E543
25
E866
>50
E473
50
E491
50
Baa
50
E515
50
E517
50
E625
50
Surface dried 60 min exposure
Quadet
oxonia
Top
Labdet
E12
Divoshaum
clear
Byosan
active
Active
Triquart
100
Salmonella
SE 30
6.25
>200
25.00
3.13
25.00
100.00
>200
>200
s6
3.13
c28
3.13
s43
6.25
c9
3.13
s25
3.13
s20
6.25
c53
3.13
ATCC 1344
1.56
Cronobacter
E462
6.25
>200
25.00
3.13
25.00
100.00
>200
>200
E543
0.39
E866
3.13
E473
3.13
E491
3.13
Baa
1.56
E515
3.13
E517
6.25
E625
6.25
Minimum
Maximum
Mean
Std. Deviation
Salmonella MIC
E12
0.10
0.20
0.19
0.04
Byodet
0.20
0.78
0.31
0.22
Byosan
0.20
0.78
0.34
0.21
Oxonia Active/Topmax 5522
1.56
3.13
2.01
0.77
Top Active DES
1.56
3.13
2.23
0.84
Triquart
1.56
6.25
3.79
2.36
Quadet clear
1.56
6.25
3.91
1.91
Labdet 100
1.56
50.00
15.18
17.51
Divoshaum
3.13
50.00
27.23
17.56
Cronobacter MIC
E12
0.20
0.20
0.20
0.00
Divoshaum
3.13
50.00
29.30
19.11
Quadet clear
0.78
3.13
1.76
0.91
Byodet
0.20
0.20
0.20
0.00
Byosan
0.20
0.20
0.20
0.00
Oxonia Active/Topmax 5522
0.78
3.13
1.47
1.06
Triquart
0.78
6.26
2.44
1.75
Top Active DES
0.78
3.13
1.86
0.83
Labdet 100
3.13
25.00
12.89
10.49
UCD E12/C-Activ-12 Product Formulation Support Studies Comparative Analysis of Formulation and Essential Oils/Active Substances
Osmotic Pressure
Strain
PBS
TSB
EU
TC
THY
E12
SP291
0.23
0.09
0.24
0.17
0.24
0.23
0.17
0.224
0.22
0.224
Ave
0.23
0.13
0.232
0.195
0.232
Strain
PBS + NaCl
TSB
EU
TC
THY
E12
SP291
0.33
0.15
0.23
0.24
0.23
0.276
0.43
0.265
0.196
0.23
Ave
0.303
0.29
0.2475
0.218
0.23
Notes:
EU, TC, Thy E12 are all diluted into the MIC concentration with TSB.
TSB is the plain TSB
Strain
PBS
TSB
EU
TC
THY
E12
E601
0.28
0.133
0.26
0.245
0.222
0.305
0.181
0.302
0.273
0.311
Ave
0.2925
0.157
0.281
0.259
0.2665
Strain
PBS + NaCl
TSB
EU
TC
THY
E12
E601
0.34
0.19
0.41
0.38
0.3
0.35
0.16
0.33
0.27
0.22
Ave
0.345
0.175
0.37
0.325
0.26
Fresh Produce Decontamination—Product Comparison Study University of Padova, Italy.—Study 1—Salad Wash Test Padova June 2011
[0131] In comparison: 2 salads (“Biological” and “Conventional”). Biological is from organic farming and it is always pre treated in-field with a mix of plant growth-protecting bacteria and fungi. Conventional is grown with pesticides and chemical fertilizers. Both salads were spiked with a culture of Escherichia coli resistant to Kanamycin by sprinkling them with a cdosage that conveyed about 3×10 7 cells per gram). 125 grams were treated for each salad. Salads were incubated 24 h at 37° C. in sealed envelopes. 4 aliquots of 25 g were taken and washed with 3 different washing for 10 minutes by stirring in 1500 ml of: 1) water, 2) 30 ppm hypochlorite, 4) 1% CebecC-Activ-12+surfactant. Salads were rinsed 3 minutes in 1 volume of water, drained and transferred to stomacher bags, to which added 150 ml of physiological solution were added. Bags were treated for 2 minutes at 230 rpm in the stomacher apparatus. The resuspension was plated on two different media (dilutions from 10° a 10 −7 carried out in duplicate) A) PCA (Plate Count Agar) for total count. Incubation at 22° C. B) agar LB+Kanamycin 30 ug/ml for Escherichia coli . Incubation at 37° C. Counts at 24 hours, further incubation for 6 days.
[0000] CFU per g fw salad LB Km 37° C. Mean St Dev Fold reduction over water* Bio Salad Water 2.79 × 10 6 1.06 × 10 6 Bio Salad Chlorine 3.51 × 10 5 1.06 × 10 5 7.95 Bio Salad C-activ-12 4.92 × 10 5 1.87 × 10 5 5.67 Conventional Salad Water 2.43 × 10 6 6.36 × 10 5 Conventional Salad Chlorine 9.90 × 10 5 2.12 × 10 5 2.45 Conventional Salad C-activ-12 5.70 × 10 4 4.24 × 10 3 42.63 CFU per g fw salad PCA 22° C. Mean St Dev Fold reduction over water Bio Salad Water 8.37 × 10 7 1.57 × 10 7 Bio Salad Chlorine 1.65 × 10 6 2.97 × 10 5 50.73 Bio Salad C-activ-12 4.50 × 10 6 2.12 × 10 6 18.60 Conventional Salad Water 2.49 × 10 8 7.21 × 10 7 Conventional Salad Chlorine 2.88 × 10 7 1.70 × 10 6 8.65 Conventional Salad C-activ-12 5.10 × 10 4 4.24 × 10 3 4882.35 *Fold reduction over water show many folds are bacteria abated, compared to water (=CFU with water/CFU with product under study)
Fresh Produce Study 2—Antimicrobial Activity of Chlorine, Iodine, and C-Activ-12 on Salmonella enteritidis and Escherichia coli—
[0132] The microorganisms were cultured in the presence of varying concentrations of chlorine, iodine and C-Activ 12 for time intervals of different lengths before being transferred to nutrient medium. Products tested—Amuchina® whose active ingredient is sodium hypochlorite, 1.15 g/100 ml (equal to 1.1 g of active chlorine). Sodium hypochlorite dilutions were prepared to give final concentrations of: 0, 10, 20, 30, 40, 50, 75, 100, 150, 200, 250 and 300 ppm. Poseidon-500 ®, Poly Vinyl Pyrrolidone iodine, 5% solution.—Dilutions of iodine were made to give final concentrations of 0, 10, 20, 30, 40, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450 and 500 ppm. CeBeC C-activ-12 (+surfactant)—The following increasing concentrations were tested: 3 μl/ml (0.3%), 6 μl/ml (0.6%), 10 μl/ml (1%), 15 μl/ml (1.5%), 30 μl/ml (3%), 50 μl/ml (5%). Preparation of inocula E. coli ATCC 8739 and a wild strain of Salmonella enteritidis isolated from a hospitalized patient were tested.—All experiments were performed on cultures of early logarithmic phase. Flasks containing 25 ml of Nutrient Broth (Merck) were inoculated and incubated with agitation for 18 hours at 37° C. The optical density of cultures was adjusted by dilution with sterile Nutrient Broth to produce a density of 2×10 7 CFU ml −1 Determination of bacteriostatic activity of the compounds.—Tests were set up using disposable multiwell plates (96 wells, 300 μl, conical bottom). The wells were filled with 60 μl solution of sodium hypochlorite or iodine, 60 μl of the bacterial suspension at a concentration of 2×10 7 CFUml-1, and 120 μl of Nutrient Broth. The plates were closed and incubated at 37° C. for 24 hours with shaking. The inhibitory effect of iodine and sodium hypochlorite was assessed by the optical density readings (600 nm) of the wells at different time intervals TO (immediately after inoculation) T — 6 (6 hours after inoculation), T — 24 (24 hours after inoculation) using a microwell plate reader (Multiskan EX, Thermo).
[0133] All experiments were performed in duplicate. Determination of bactericidal activity of the compounds—After 6 and 24 hours of exposure to the antimicrobials, 20 μl of bacterial suspensions were transferred into 180 μl of Nutrient Broth. From this first dilution, an aliquot of 20 μl was transferred to 180 μl of Nutrient Broth to obtain the dilution of the solutions of antimicrobials and a reduction of the initial inoculum to about 1×10 4 microorganisms. The inoculated microwell plates were incubated at 37° C., stirred for 24 hours before determining the microbial growth using optical density readings.
Collection of the Results—
[0134] The MIC (minimum inhibitory concentration) was defined as the lowest concentration of antimicrobial at which there was no growth of microorganisms after 24 hours. The MBC (minimum bactericidal concentration) was defined as the lowest concentration of antimicrobials after which there was no re-growth of microorganisms in the medium upon the above dilution and transfer. Variation of the protocol to suit the properties of C-Activ-12 The spectrophotometrical reading of the bacterial cultures turned out to be affected by the brown colour of C-activ-12, which interfered in the OD600 absorbance. Therefore the initial set up of the multiwell plates was substituted with an incubation in 100-ml flasks using 24 ml of Nutrient Broth and assessment of colony forming units after exposure to the different concentrations of the product for the three time intervals. In practice 70 μl, 140 μl, 240 μl, 360 μl, 720 μl, 1200 μl of C-Activ-12 were added to the flasks along with 6 ml of the bacterial suspension at a concentration of 2×10 7 CFU/ml. The flasks were incubated at 37° C. in agitation for 24 hours. After 0, 6 and 24 hours of exposure, 1 ml of each bacterial suspension was transferred into PBS buffer and serially diluted. Volumes of 1 ml for each dilution were seeded in triplicate for inclusion in a growth medium (Nutrient Agar). The plates were incubated at 37° C. for 24 hours. Results—Chlorine and iodine display straight bactericidal activity (MIC coincides with MBC).
[0135] The two microorganisms show a different sensitivity only with respect to iodine and C-Activ 12. Escherichia coli was more resistant, with MBC values higher than those of Salmonella enteritidis .—The MBC for chlorine is 150 ppm for both organisms (Table 1). Iodine has less bactericidal activity than chlorine (Table 1) showing higher MBC — 24 concentration: 450 ppm and 500 ppm respectively for Salmonella and E. coli . The MBCs for C-Activ-12 at 6 h and 24 h for Salmonella enteritidis and Escherichia coli have different values for the two organisms tested (Tables 2 and 3). Salmonella enteritidis , in fact, shows a MBC to T — 6 of 50 μl/ml, while T — 24 μl/ml is 15. Escherichia coli however, shows a higher resistance: in fact, the MBC T — 6 is >50 μlml-1, while the MBC in T — 24 μl/ml is 30. As regards C-Activ 12 as Tables 2 and 3 show, there are interesting phenomena, for E. coli the 1.5% concentration at 24 h exposure brings about a higher than six log reduction (from 9.60 to 3.35) and higher concentrations (3% onwards) yield a complete abatement of vitality. For Salmonella the >6 log reduction is seen already at 6 h of exposure with the 3% solution and the fully clean plates are seen at 24 h also with the 1.5%. The mode of action appears to rely on a time-dependent mechanism as the 6 h exposure shows effects that reach higher severity at 24 h. A noteworthy parallel observation is that the yellowish colour of the C-Activ-12 solution tends to fade out in the bacterial cultures in a manner that appears inversely proportional with their vitality. I.e. the more they die the less C-Activ 12 seems to be left in solution. This suggests a gradual partitioning of the colour-absorbing compounds into the bacterial cells for which compartments (e.g. membranes) there could be a chemical affinity.
Effectiveness of C-Activ-12 Against Powdery Mildew (Plant Fungus) University of Padova Italy—Activity of C-Activ-12 Against Plant Pathogen PSA—University of Padova Italy
[0136] The results of the MIC activity of C-Activ-12 on P. syringae pv. actinidiae and the quantification of its bacteriocidal effect upon exposure are provided and indicate that the product is very active up to a concentration of 0.125% to 0.0625% depending on the strain. It has a marked acidifiying activity but its biocidal effects are independent from the pH factor (see controls with HCl and NaOH). A 5 min contact of cells with a 0.5% concentration abates their viability by 43-fold.
PSA Study—MIC Assay:
[0137] Bacteria tested: Pseudomonas syringae pv. actinidiae strain 8.43, Pseudomonas syringae pv. actinidiae strain 8.43a, Source: Marco Scortichini CRA Rome; Growth medium: Nutrient Broth+5% Sucrose (NSB medium); Pre-inoculum: Exponential phase liquid pre-cultures in 10 ml (having reached a viable cell count of 0.7×10 7 CFU/ml); Product under study: C-Activ-12—Dilutions tested (and corresponding concentrations): 1:100 (1%); 1:200 (0.5%); 1:400 (0.25%); 1:800 (0.125%), 1:1600 (0.0625%); 1:3200 (0.0312%); Procedure Tests were done in 50 ml falcon tubes containing 10 ml of NSB medium supplemented with decreasing amounts of C-Activ-12 to yield the above concentrations. Tubes were inoculated with 10 μl of bacterial preculture. As control tubes without C Activ-12 were set up. Incubation: 28° C. stirring; Measurement: Bacterial growth (turbidity) was inspected after 18 h and after 48 h; Other Controls and their rationale In addition to the above described standard tests, a number of controls was run. Control of C-Activ-12 sterility. In order to rule out that bacteria other that the ones under study could grow as a result of their cells or spores being possibly present in the C-Activ-12 stock itself. A series of tubes with the same C-Activ-12 dilutions in NSB was done, to which the inoculum of P. syringae pv. actinidiae was not added. Control of acidity effects. In order to distinguish between inhibitory effects of the C-Activ-12 compounds and those brought about by the low pH consequent to the addition of C-Activ-12 to the medium, the pH values corresponding to the different dilutions in NSB medium were measured prior to miming the assays. Afterwards, the exact amounts of defined HCl solutions (1N and 0.1 N) to be added to NSB medium were determined in separate batches using a pH meter. With these data a series of tubes was set up in which those pH values were achieved by adding the required amounts of filter-sterilized (0.22 μm) HCl solutions. Aliquots to be added to the 10 ml cultures were in the range of 50 to 400 μl de3pending on the target pH. In these tubes therefore no C Activ-12 was added while the effects on bacterial growth of the corresponding HCl-generated pH values were assessed. Control of C-Activ-12 effects at re-neutralized pH. In order to uncouple the growth inhibiting effect due to the C Activ-12 mechanism to that given by the acidity that it conferred to the solution, a series of tubes with the above mentioned dilutions were corrected back to near-neutral pH using filter-sterilized NaOH 0.1N or 1 N solutions. The exact amounts to be added had been previously calculated experimentally by serial additions of NaOH to separate batches of NSB using a pH meter. Results=
[0000]
Strain
C-Activ-12 concentration
pH*
Growth at time = 18 h
Growth at time = 48 h
8.43
0
7.08
+++
+++
8.43
1%
3.75
−
8.43
0.5%
4.27
−
−
8.43
0.25%
4.91
−
−
8.43
0.125%
5.58
−
−
8.43
0.0625%
6.38
−
−
8.43
0.00312%
6.75
−
+++
8.43a
0
7.08
+/−
+++
8.43a
1%
3.75
−
−
8.43a
0.5%
4.27
−
−
8.43a
0.25%
4.91
−
−
8.43a
0.125%
5.58
−
−
8.43a
0.0625%
6.38
−
+++
8.43a
0.00312%
6.75
−
+++
a) Sterility Control of C-Activ-12 alone without P. syringae pv. actinidiae
None
1%
3.75
−
−
None
0.5%
4.27
−
−
None
0.25%
4.91
−
−
None
0.125%
5.58
−
−
None
0.0625%
6.38
−
−
None
0.00312%
6.75
−
−
b) pH effect without C-Activ-12 (obtained by HCl)
8.43
3.74
−
−
8.43
4.34
−
−
8.43
4.60
−
−
8.43
5.65
−
−
8.43
6.56
−
−
8.43 (No HCl)
7.08
+++
+++
c) C Activ-12 activity in broth re-neutralized with NaOH
8.43
1%
6.97
−
−
8.43
0.5%
6.92
−
−
8.43
0.25%
6.91
−
−
8.43
0.125%
6.90
−
−
8.43
0.0625%
6.90
−
−
8.43
0.00312%
6.95
−
+++
*the pH indicated is meant as the one at the beginning of the test. The values are deduced from parallel pH meter tests with given amounts of medium and C-Activ-12. or HCl, or NaOH as appropriate.
Ranking: −: no growth; +/−: very slight turbidity; +++: full growth (OD600 >0.8).
Note:
at 1% and 0.5% dilutions the C-Activ-12 in NSB medium presents a slight presence of flocculating material, this is independent from the bacterial presence as it occurs also in the tubes without bacteria.
Comments
MIC: The minimum inhibitory concentration of C-Activ-12 resulted between 0.0625% (MIC for strain 8.43) and 0.125% (MIC for strain 8.43a).
The C-Activ-12 results sterile and does not convey growing biota under the assayed conditions.
The pH values corresponding to those conferred by most C-Activ-12 dilutions are themselves inhibitory to the growth of P. syringae pv. actinidiae . This species showed a particular sensitivity to pH/HCl values below neutrality. It is worth noticing that at a pH as low as 6.56 there is already a clear growth inhibition.
C-Activ-12 is nevertheless shown to be active also when the pH is neutralized by NaOH indicating that the growth inhibition is not due to acidity but to a genuine antagonistic mechanism exerted by its ingredients.
Bacteriocidal Efficiency Assay—
[0138] Besides determining the MIC, we assessed the capability of C-Activ-12 to permanently reduce viability of P. syringae pv. actinidiae upon contact with it at the 0.5% concentration. The abatement of colony forming units on plates was measured as follows:
[0000] Mezzo nutritivo: NB+5% Sucrose (10 ml); Pseudomonas syringae pv. actinidiae ceppo 8.43 (inoculo 10 μl in 10 ml); Sostanza da saggiare: C-Activ-12
5 ul of C-Activ-12 were added to 1 ml of exponential phase liquid pre-culture of P. syringae pv. Actinidiae strain 8.43 (1:200 dilution→yielding a 0.5% C-Activ-12 concentration) The suspension was mixed and incubated 5 minutes at 20° C. 100 μl of such suspension were transferred in a 50 ml sterile falcon tube and diluted to 10 ml with sterile saline solution, causing a dilution of C-Activ-12 of 1:20000 which is far beyond its MIC range. Serial dilutions were carried out in sterile saline solution and plated on NSA plates (Nutrient Agar with 5% Sucrose). A parallel test with the same cells was run without adding C-Activ-12. The CFU counts between control and C-Activ-12 treated cells were compared.
Results:—Control: 0.7×10 7 CFU/ml—Exposed for 5 min to 0.5% C-Activ-12: 1.6×10 5 CFU/ml
Comments:—
[0142] The treatment, with this exposure time and concentration, thus proved able to cause a 43-fold reduction in the titre of culturable cells, corresponding to an about 1.5 log reduction.
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A process for preparing a biocidal composition comprising the steps of: (i) dissolving at least one polyol in water to form a water/polyol co-solvent solution; (ii) adding at least one organic acid to the water/polyol co-solvent solution; (iii) adding at least one stabiliser to the water/polyol co-solvent solution; (iv) adding a flavonoid composition comprising at least one flavonoid selected from the group consisting of: poncirin, neoeriocitrin, isonaringin, rhoiflin, naringen, neodiosmin, hesperidin, neohesperidin and naringenin.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of application Ser. No. 11/703,442 filed Feb. 7, 2007, which was a division of U.S. application Ser. No. 11/376,731, now U.S. Pat. No. 7,203,595, filed Mar. 15, 2006, the entire disclosure of which is incorporated by reference herein. U.S. application Ser. No. 11/376,731, now U.S. Pat. No. 7,203,595, filed Mar. 15, 2006, is related to previously filed U.S. application Ser. No. 11/376,715 filed Mar. 15, 2006, entitled “Method of displaying traffic information on a web page.”
BACKGROUND OF THE INVENTION
[0002] Currently, when information about traffic on a road or series of roads is communicated in commercial broadcasts, written traffic reports or even in casual conversation, terms such as ‘jammed’, ‘bottled up’, ‘moderate’ and ‘heavy’ are often used. These terms provide little or no specific information to the listener or viewer. Terms such as these are imprecise in that they simply express that traffic is not traveling at the maximum potential speed for the road. Additionally, terms such as these are very subjective. What one person might describe as ‘moderate’, another person might describe as ‘jammed’ based on their frame of reference. Yet, most people would agree that ‘moderate’ and ‘jammed’ are not equivalent descriptions of traffic conditions. What is needed is an objective, precise, quantitative way to express information about the level of traffic so that a listener or viewer of that rating will have an understanding of the meaning of that information and that the information will be useful to them.
BRIEF SUMMARY OF THE INVENTION
[0003] The present invention provides a “Jam Factor” rating that represents the status along a specified driving route. The driving route is specified such that the route includes at least one road. A free flow travel time is calculated for the specified route. Then, the total delay is calculated for the specified route. The free flow travel time and the total delay are summed to obtain the total estimated travel time along the specified route. A delay multiple is then calculated by dividing the total travel time by the free flow travel time. The Jam Factor rating is then calculated based on the delay multiple.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
[0005] In the drawings:
[0006] FIG. 1 shows generic examples of Jam Factors for various traffic situations.
[0007] FIG. 2 shows specific examples of Jam Factors for the commute segment I-76 from the PA Turnpike to the Walt Whitman Bridge.
[0008] FIG. 3 a shows the user interface display screen for selecting a drive name and metro (metropolitan) area.
[0009] FIG. 3 b shows the user interface display screen for selecting a starting roadway.
[0010] FIG. 3 c shows the user interface display screen for selecting start and end points on starting road.
[0011] FIG. 3 d shows the user interface display screen for selecting a continuation to a connecting roadway.
[0012] FIG. 3 e shows the user interface display screen for selecting to end a commute.
[0013] FIG. 3 f shows the user interface display screen for viewing drives and overall Jam Factor for those drives.
[0014] FIG. 3 g shows the user interface display screen for viewing the Jam Factor (item 10) for the individual roadway sections along a specific previously created drive. Additionally, the display also shows incidents (item 20) on the individual roadway sections.
[0015] FIG. 4 a shows the Magnet Product Page which a user will see when they first access the magnet website (or are not logged in).
[0016] FIG. 4 b shows a screenshot of the pages of the Traffic Magnet registration page where user information is entered.
[0017] FIG. 4 c shows a screenshot of the Traffic Magnet registration page that displays the User Agreement and Privacy Policy.
[0018] FIG. 4 d shows an example of a magnet on the maintenance page.
[0019] FIG. 4 e shows a screenshot of the magnet creation page where user information is entered.
[0020] FIG. 4 f shows a screenshot of the magnet creation page where the format of the magnet is selected.
[0021] FIG. 5 shows examples of the layouts of a horizontal magnet and a vertical magnet.
[0022] FIG. 6 shows some of the different styles of magnets available to the user.
[0023] FIG. 7 shows the database schema for the Traffic Magnet data.
[0024] FIG. 8 shows a Data Flow Diagram for the user interface for the creation of a Traffic Magnet.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. In the drawings, the same reference letters are employed for designating the same elements throughout the several figures.
[0026] The present invention is described in the context of two services, namely, TrafficMagnets™ and Jam Factor™ reports, both of which are commercially available from Traffic.com, Wayne, Pa. However, the scope of the present invention includes other embodiments that may differ from the specific implementations provided by the TrafficMagnets and Jam Factor reports. The present invention is also preferably designed to work in conjunction with systems and methods described in copending U.S. patent application Ser. No. 10/611,494 filed on Jun. 30, 2003, entitled “Method of Creating a Virtual Traffic Network,” which is hereby incorporated by reference. However, the scope of the invention includes embodiments that do not necessarily incorporate the methods and apparatus described in this patent application.
[0000] I. Overview of Jam Factor Rating
[0027] The jam factor of a route is a value between 0 and 10 which indicates the ease of travel along the route. All clear would be a number towards 0, and completely jammed/stopped would be a number towards 10. Jam Factor calculations will be done primarily through delays (from free flow travel).
[0028] Determining delay for a digital route is done through sensor values. For a non-digital route, the delay is calculated through the incidents along the route. For routes which contain both digital and non-digital sections, separate calculations are done for each section and the final delays are added together.
[0029] Any road closure along the route will automatically create a Jam Factor of 10.
[0000] II. Calculations of Jam Factor Rating
[0000] 1. Delay for Digital Routes:
[0030] The delay is calculated from the real-time sensor values. If there are any problems determining the delay from the sensors (sensors are no longer working, data is determined to be invalid), then the non-digital calculations are used for this route. Also, traffic items are still checked to determine if there is a road closure. Otherwise, traffic items are ignored for digital routes.
DigitalDelay = RouteLength SensorSpeed - RouteLength SpeedLimit
In the preferred embodiment of the present invention, the delay is never expressed as a negative number. Thus, if traffic is moving faster than the speed limit, the delay is reported as being zero.
2. Delay for Non-Digital Routes:
[0031] Delay for non-digital routes is calculated through the traffic items that occur along the route. There are two separate delays that are calculated, one for the congestion items and one for high criticality items which are not attributed (or linked) to a congestion item.
[0000] a. Congestion Delay:
[0032] Each congestion item will have a type associated with it which describes the level of congestion seen along the road. These congestion types will map to an estimated average speed, allowing a travel time to be calculated for the length of the congestion. Individual congestion delays will then be determined by calculating the difference between the free flow travel time and the congestion travel time. The total congestion delay will be the sum of all the individual congestion item delays.
CongestionTT = CongItemLength CongItemSpeed
FreeFlowTT = CongItemLength RouteSpeedLimit
CongestionDelay = ∑ i = 1 £ congitems ( CongestionTT i - FreeFlowTT i )
TABLE 1 Congestion Speeds (based upon 60 mph roads): Congestion Type Speed (mph) Stopped 2 Jammed 10 Generally Jammed 20 Slow 30 Generally Slow 40 Sluggish 48 Note: For roads with speed limits other than 60 mph, the congestion speeds will be adjusted according to the same percentages.
b. Incident Delay:
[0033] Incidents must be taken into account when there are no corresponding congestion items linked to them. A value will be looked up in a table that matches incident attributes with assumed delays. In one preferred embodiment, only the criticality of the incident is taken into account. All incidents that have a child congestion item will be ignored since they should already be accounted for by the congestion calculation above.
IncidentDelay = ∑ i = 1 £ items ( Delay i )
[0034] The following table may be used to map the criticalities of incidents to an estimated delay.
TABLE 2 Criticality Delays: Criticality Delay (min) 0 20 1 10 2 5 3 2
3. Jam Factor:
[0035] The Jam Factor is determined by first comparing the estimated travel time to the free flow travel time. This comparison is referred to as the Delay Multiple.
DelayMultiple = FreeFlowTT + TotalDelay FreeFlowTT
where :
FreeFlowTT = KR_Length SpeedLimit
[0036] This Delay Multiple can be directly associated to the Jam Factor by an exponential equation where the Jam Factor equals 0 when the delay multiple equals 1 (no delay) and the Jam Factor approaches 10 as the delay multiple grows very large. A set of logical plot points along the curve was determined to create a graph of Jam Factor vs. Delay Multiple. Linear interpolation can then be used to determine the jam factor when the delay multiple lies between the plot points.
[0037] Below is a table of delay multiples with expected Jam Factors.
TABLE 3 JamFactor Points: Speed Delay Based on 60 mph Point # Multiple Jam Factor limit 1 1 0 60 2 1.25 3 48 3 1.5 5 40 4 1.75 6 34.2 5 2 7 30 6 3 8 20 7 8 9 7.5 8 32 10 2
[0038] To calculate the Jam Factor for a specific delay multiple, the following equation is used (which utilizes the two points that the delay multiple falls between):
prev=point preceding the actual delay multiple next=point following the actual delay multiple
JamFactor = JamFactor next - JamFactor prev DelayMultiple next - DelayMultiple prev * ( DelayMultiple actual - DelayMultiple next ) + JamFactor next
[0041] FIG. 1 shows generic examples of Jam Factors for various traffic situations.
[0042] FIG. 2 shows specific examples of Jam Factors for the commute segment I-76 from the PA Turnpike to the Walt Whitman Bridge.
[0043] III. Creating and Viewing a Jam Factor Rating
[0044] FIGS. 3 a through 3 g describe the process of creating a drive and viewing a Jam Factor for that drive. These figures are self-explanatory and thus will be described only briefly.
[0045] FIG. 3 a shows the user interface display screen for selecting a drive name and metropolitan area.
[0046] FIG. 3 b shows the user interface display screen for selecting a starting roadway.
[0047] FIG. 3 c shows the user interface display screen for selecting start and end points on starting road.
[0048] FIG. 3 d shows the user interface display screen for selecting a continuation to a connecting roadway.
[0049] FIG. 3 e shows the user interface display screen for selecting to end a commute.
[0050] FIG. 3 f shows the user interface display screen for viewing drives and overall Jam Factor for those drives.
[0000] V. Specifications for a Traffic Magnet
[0051] The Traffic magnet project can be separated into two distinct components: (1) Traffic Magnet registration/maintenance, and (2) Traffic Magnet generation.
[0000] 1. Traffic Magnet Registration/Maintenance
[0052] The user interface for creating traffic magnets is preferably web based, and located at http://magnet.traffic.com.
[0053] FIG. 4 a shows the Magnet Product Page which a user will see when they first access the magnet website (or are not logged in). This page will show examples of the various magnets that they can create for their website. From this page, a user can register for the service, or login if they have already registered.
[0000] a. Registration
[0054] FIGS. 4 b and 4 c show the registration page. The following data will be requested from the user:
TABLE 4 User Registration Information: First Name Optional. Last Name Optional. User Name Required. 6-12 characters Password Required. 6-12 characters E-mail Address Required. Company Name Optional. Phone Number Optional. Street Address 1 Optional. Street Address 2 Optional. City Optional. State Optional. Zip Code Optional.
[0055] The user must enter in the required fields, and also agree to the terms and conditions for using the magnet service, in order to create an account. The data entered is saved in the traffic_user table in the database. The user creation date is also saved to verify when the user signed up and agreed to the terms and conditions. FIG. 7 shows the database schema.
[0056] After the user successfully creates an account, they can then log into the system with their newly created username and password.
[0057] FIG. 3 g shows the user interface display screen for viewing the Jam Factor (item 10) for the individual roadway sections along a specific previously created drive. Additionally, the display also shows incidents (item 20) on the individual roadway sections.
[0000] IV. Overview of a Traffic Magnet
[0058] A Traffic Magnet is a snippet of programming code that allows an end user to include live traffic information on their web site and provides a link from their site to a remote site containing the traffic information, such as Traffic.com. A remote site is defined as an entity other than the internet or intranet content provider.
[0059] Placing a Traffic Magnet on a web site allows the end user to provide live traffic information about the roads surrounding the end user's physical location to users of their web site who will travel to or from that physical location. Additionally, having such links embedded in many web sites provide benefits to the remote site (here, Traffic.com), such as driving internet traffic to the remote website, increasing brand awareness of the remote site, and improving search engine ranking of the remote site (when done using embedded HTML).
[0060] One preferred embodiment of a web-based Traffic Magnet product allows Traffic.com users to configure the magnet by selecting up to four roadways to track (in both directions), and one of several backgrounds. Configuration occurs through a web interface. Registration is preferably required for access to this interface. The output of the product is a snippet of HTML/Javascript that the user paste into their web page. Traffic information in the magnet will be provided on a Route basis. A single magnet will show several Routes but they must all belong to the same metropolitan area. Traffic.com may have the ability limit the number of magnets a user can create, but most likely there would not be a limit unless users abused the service. The terms and conditions may include a clause about users not abusing the service.
[0061] Backwards compatibility—magnets may have some static links which need to remain functional. Also, it is possible for the magnets to contain hardcoded route ID's. If they do, these keyroutes must not be deleted and the ID's must not be changed.
[0062] Tracking and Reporting site traffic—A user's magnets will be stored in the database. By attaching this magnet ID or user ID to all the inbound links, Traffic.com can track the traffic generated by specific users.
[0000] b. Magnet Maintenance
[0063] FIG. 4 d shows an example of a magnet on the maintenance page. After a user is logged in, they will be forwarded to the magnet maintenance page where they will see a list of their previously created magnets. The actual magnets will be displayed, along with a text block containing the magnet code snippet and a button to delete the magnet. Users will not be able to edit a magnet. If they want to change a magnet style, or the keyroutes associated with a magnet, they will need to delete it and create a new one.
[0000] c. Magnet Creation
[0064] After logging in, a user will also be able to create a new magnet. The style of the magnet will determine the magnet size. Each magnet style has a standard size (e.g., 410×285 horizontal, 200×605 vertical).
[0065] Information on magnet styles will be contained in the database (Refer to FIG. 7 for the database schema). The styles will define the layout, background, orientation and color scheme of the magnet. A user will select from one of these styles when creating their magnet. The following fields will be needed to define a magnet style.
TABLE 5 Fields Defining Magnet Style Magnet Magnet Style Name Name of Magnet Position H (Horizontal) or V (Vertical) Image Example Image File Name Width Width of the magnet Height Height of the magnet Velocity Template Template defining the html style and format for this magnet
[0066] Magnets will also contain links to the website, promotions, advertisements, etc. This information can be different between metropolitan areas and may be updated at random times. It will be separated into two sections on the magnets. Each section will have its own html. The users have no control over this information. The following data needs to be stored in the database to create these html blocks.
TABLE 6 Data for Creation of HTML Blocks Magnet HTML MetroId Metro Id of magnets that link will show up on Magnet HTML 1 HTML to be displayed in the first section Magnet HTML 2 HTML to be displayed in the second section
[0067] The user will be shown examples of magnets during creation in order to select the style they want for their website. (Note: terms of service must outline proper use of magnet. e.g. magnet can only exist at domain on one (1) page, etc.)
[0068] FIGS. 4 e and 4 f show screenshots of the magnet creation page. The following information needs to be captured for each magnet that the user creates. This data not only defines the user's magnet, but also gives us more information to be used to better track how the magnet is being used. The user will be allowed to select up to four roads for a magnet (which will equate to eight routes, when direction is taken into account). Although a user may create magnets for different metropolitan areas, an individual magnet will only be applicable to a single metropolitan area.
TABLE 7 Information captured for each magnet a user creates User Magnet Company Name Optional. Industry Optional. Home Page Address Required. Traffic Page Address Required. Magnet Description Required. Magnet Style Name Required. Metro Id Required. Route Id 1 Required Route Id 2 Optional Route Id 3 Optional Route Id 4 Optional
[0069] After a user creates their magnet, they will be directed back to the magnet maintenance page where they can see their new magnet. They will also have access to the code snippet to include the magnet on their website.
[0070] d. Traffic Magnet Creation Use Cases
TABLE 8 Steps - User registers for a magnet account UC01 Use Case 1 User registers for a magnet account Step User Action Result Figure Alternate 1 User goes to User sees Magnet Product N/A magnet.traffic.com Page 2 User Clicks on “Sign Up Go to registration page FIG. 2b & Now” button 2c 3 User Enters Values defined User is now registered standard in 0 and submits form error
[0071]
TABLE 9
Steps - User logs into magnet account
UC02 Use Case 2
User logs into magnet account
Assumes user has registered and verified email address
Step
User Action
Result
Figure
Alternate
1
User clicks on “Login” link
Go to login
N/A
page
2
User enters name and
Go to magnet
Standard
password and clicks submit
maintenance
error
page
[0072] TABLE 10 Steps - Registered User Creates a Traffic Magnet UC03 Use Case 3 Registered User Creates a Traffic Magnet Assumes user has registered and logged in explicitly during this session. Step User Action Result Figure Alternate 1 Chooses to create magnet Go to magnet set up page FIG. 2e & N/A 2f 2 Enter Company, Site N/A standard information error This information is required. Alternate processing is standard error handling for these elements. 3 Enter Magnet Values N/A standard error User selects metro area, which populates keyroute list. User can select up to 4 keyroutes (Javascript validation), and one background image. 4 Confirm Legal Agreement N/A standard error User is required to check on “Agree” radio button. 5 User selects ‘continue’ Go to Magnet Maintenence Magnet maintenance page gives user some indication about how to use html snippet and provides code in a scrolling text pane. User has to copy HTML in order to paste into their page.
VI. Traffic Magnet Generation
[0073] Traffic magnets are displayed through a code snippet that a user places on their website. The code snippet will contain links to javascript files located on the traffic.com servers, as well as some static html. The javascript files will be auto generated on a regular basis so that a user is accessing a static file. The traffic magnets will contain links back to specific areas on the www.traffic.com website. All links and images in the magnet will have a referral id to track statistics on magnets. HTML provided will be standards compliant and valid, with all styling accomplished through the use of inline CSS.
a. Example Magnets
[0074] FIG. 5 shows examples of the layouts of a horizontal magnet and a vertical magnet.
b. Magnet Content
[0075] A Magnet will be applicable to a single metropolitan area and will contain information on one to four routes. Each route section of the magnet may contain any or all of the following information:
[0000] Roadway Name and Direction
[0000]
Roadway Shield (if applicable to the road)—Four different shield types (U.S. state, interstate, county) with the road number overlaid on top.
Incident Icon—Triangle with the number of incidents along route inside. The triangle border will be colored red if there are any high criticality incidents, and yellow if there are any medium criticality incidents.
Jam Factor—Visual representation of route conditions, equating to a number between 0 and 10.
The magnet will also contain the following information: Metro Name, Timestamp of route data, and two sections for metropolitan specific advertisements and links.
c. One Preferred Embodiment for Generating Magnets
[0080] The process for generating magnets needs to be a compromise between flexibility, security and scalability. One preferred solution is to use Javascript as the main piece of the code snippet that the user pastes on their webpage. This is not as scalable as using straight HTML code, but gives much more flexibility to change the content of the magnet without affecting the user's website. It also makes it more difficult for the user to try and modify the look of the magnet (which should be a violation of the Terms and Conditions). The downside to this solution is that it will not improve the search engine ranking. To try and overcome the search engine ranking problem, some static html must be included in the magnet code snippet which refers back to the traffic.com website.
[0081] The javascript will be contained in files on traffic.com servers, and the user's code snippet will simply point to the proper files for the respective magnet. The javascript will be generated in two parts. One part will generate the user's magnet code in a file named magnet.js. The other part will generate the code for each route section of the magnet in files named keyroutedetails.js. A single magnet code snippet will then point to one magnet.js file (which will include references to the applicable keyroutedetails.js files).
[0082] Since the user cannot directly manipulate the Javascript code, Traffic.com can enforce that each link on the magnet will contain information identifying the magnet user. This will allow Traffic.com to easily track the traffic coming from each user/magnet through the Apache web logs.
[0083] i. Route Information Generation
[0084] Route information will be pre-generated every two minutes for each known route in the metro area. The process will create ajavascript file (keyroutedetails.js) and an incident icon (incident.gif) for every route. This information will be shared by all magnets which contain the same route. The keyroutedetails.js file will contain methods for retrieving the timestamp and jam factor for a route. The incident icon will be an image file determined through the incidents along the route. The two generated files will be placed on the magnet.traffic.com server in a location similar to keyroutes/metro<metroid>/keyroute<routeid>_<route-direction>. The text in between “<>” is text that is replaced by real data during processing.
[0085] The incident icon is chosen from an incident image repository based upon the current incidents along the route. The image repository will contain all of the possible variations of incident icons (icons with yellow, red and clear borders as well as numbers from 0-9 inside). The proper image is selected by counting the number of incidents along the route (which determines the number) and finding the highest criticality incident (which determines the border, red for high criticality and yellow for medium criticality). The image file is renamed to incident.gif when moved to the route directory defined above.
[0086] The javascript file will contain a method for getting the timestamp of the data (getTime) and two methods to create the jam factor image (getVertJamFactor<routeid> for vertical magnets and getHorizJamFactor<routeid> for horizontal magnets). The jam factor image is created by using a static image for the multi-colored background bar and having 11 different rectangular slider bar locations for each integer from 0-10. The left most location will be 0, and the right most 10. The jam factor value will be truncated to one decimal place and shown on the rectangular slider. The slider location is determined by the whole number value of the jam factor. The slider color also changes with different locations.
[0087] ii. Magnet Information Generation
[0088] The magnet Javascript file will be pre-generated on an as-needed basis. All active magnets will be created when the magnet generation process starts. After the initial creation pass, the process will check for all magnets labeled as “dirty” to recreate. A magnet may be labeled as dirty when:
Magnet is created Magnet is deleted Route changes are made to the system, affecting specific route ID's Design for a style changes Magnet html for a metro changes.
[0094] Magnet information consists of the magnet.js file and symbolic links pointing to the route directory (created by the process noted above) for each route in the magnet. This information is placed in a location similar to magnets/metro<metroid>/<userid>/<magnetid>.js. The symbolic links hide the actual location of the keyroute information so users cannot easily find and use content outside of their magnet definition. When a magnet is deleted, the symbolic links are broken and a “deleted” version of the magnet.js file is created. In this manner, the user no longer has access to any of the information.
[0095] FIG. 6 shows some of the different styles of magnets available to the user. Magnet style templates are saved in the database and used to generate the magnet.js file. There are multiple styles that the user can choose from for displaying the selected route content. The user chooses a style for each magnet. The user also selects the routes which will appear on the magnet. When a magnet is generated, the style template is pulled from the database and the selected routes are used to create the route sections. The route name, direction, ID, shield type and roadway number are all needed by the template.
[0096] The real-time parts of the magnet are the timestamp, the jam factor for each route, and the incident icon for each route. The content of the magnet javascript file changes very infrequently, but will still contain real-time data by calling methods on the above-generated keyroutedetails.js files. The jam factor method called will be determined by the magnet orientation (horizontal/vertical) and route ID's. For example, the method getHorizJamFactor456( ) will be used for route 456 in a horizontal magnet. The time is retrieved by calling getTime( ) which exists in each keyroutedetails.js file and should have the same time for all routes in a metro. The incident icon (incident.gif) for each route, which changes with the keyroutedetails.js file, is included in the magnet through the symbolic link paths.
d. Alternative Embodiment for Generating Magnets
[0097] In another embodiment of the present invention, only traffic conditions are requested from the remote site. In this embodiment, the user retrieves all of the code in the snippet needed to assemble the magnet, and the dynamic pieces of the magnet (traffic data), via XML. Instead of the code snippet being a link to a javascript file, it is a snippet of html and javascript which creates the entire magnet, minus the real time traffic data. The traffic data (and only the traffic data) can then be downloaded on a regular basis from the Traffic.com web site to fill in on the magnet. The XML can be generated as a separate file for each metropolitan area containing the real-time data for the metropolitan area keyroutes.
[0000] VII. Data Flow Diagram for the User Interface
[0098] FIG. 8 shows a Data Flow Diagram for the user interface. The steps in the diagram are explained as follows:
[0099] 10. User specifically types in or is directed to the magnet.traffic.com domain
[0100] 20. The application checks if there are any browser cookies available which specify that the user has already logged in.
[0101] 30. If the login cookie exists, the user information is pulled from the cookie and the user is directed to the magnet maintenance page (See section V.1.b).
[0102] 40. User selects to create a new magnet and is directed to the magnet creation page to select the details of the new magnet (See section V.1.c).
[0103] 50. If magnet is successfully created, the user is redirected back to the magnet maintenance page to see their new magnet and the code snippet necessary to place on their website (the actual magnet may take a few minutes before it can be seen on the page, but the code snippet is available immediately).
[0104] If the magnet could not be created, the user is directed back to the magnet creation page (with all their selected values pre-filled) and a message specifying which form field needs to be addressed to fix the problem.
[0105] 60. If the user is not logged in when going to magnet.traffic.com, they will be directed to the magnet home page (See section V.1).
[0106] 70. If a user selects to register from the magnet home page, they are directed to the registration sign up form (See section V.1.a).
[0107] 80. If there was an error during registration, the user is redirected back to the registration page (with all their selected values pre-filled) and a message specifying which form field needs to be addressed to fix the problem.
[0108] If registration was successful, the user is redirected to the login screen to use their newly created username and password for entry into the magnet website.
[0109] 90. If a user has forgotten their password, they can enter their username on this form and receive an email containing their password.
[0110] 100. The user can login from the home page by entering their username and password into the proper fields.
[0111] 110. If the login is successful, the user will be redirected to the magnet maintenance page. If the login is not successful, they will be redirected back to the login page and notified that their username/password combination was incorrect.
[0000] VIII. Reporting Internet Traffic from Traffic Magnets
[0112] The necessary data for reporting internet traffic from traffic magnets is collected and saved. Accordingly, statistics can be generated at any time. There are two different sets of data being collected. One set is the information collected when the user is maintaining their magnets and is saved in the database. The other set of data is the web traffic information related to the magnets and is collected through Apache server web logs. All URLs in the magnets contain a reference to the current magnet, which not only allows Traffic.com to determine the number of times the magnet is loaded, but also which magnets are driving traffic back to the main website. All Apache web logs are saved off to a separate server on a daily basis. These logs can be parsed by a Perl script or Java process to retrieve necessary information. Tables 11-13 outline the requested reporting areas.
TABLE 11 Aggregate Data Aggregate Data: Grand Totals Total # of Accounts [db] # of Active Accounts (accessed in prior month) # of New Accounts (in prior month) [db] # of Deleted Accounts [db] Total # of Magnets [db] # of Active Magnets # of New Magnets [db] # of Deleted Magnets [db] # of Unique Users across all Accounts/Magnets # of Accesses/Pageviews across all Accounts/Magnets # of Clickthroughs to www.traffic.com Aggregate Data: Metro Totals - same as Grand Totals but broken down by Metro
[0113]
TABLE 12
Detailed Data for each Account/Magnet
Detailed Data for each Account/Magnet:
All Account and Magnet configuration info (Company, url, metro,
Keyroute list, etc. [db]
# of Unique Users per Magnet
# of Accesses/Pageviews per Magnet
# of Clickthroughs to www.traffic.com
[0114]
TABLE 13
Data for magnet.traffic.com web site
Data for magnet.traffic.com web site
# of UVs per Page (home page, signup, magnet setup, etc.)
# of Pageviews per Page
Ideally: Clickstream data to give visibility into where users go on the
site (% who follow each link on each page vs. leave the site)
[0115] Some of this information will be determined through the database. The rest will need to parsed from the Apache web logs. After parsing the Apache web logs, the result data can either be stored in the database or emailed to a specific list of addresses.
[0116] The present invention may be implemented with any combination of hardware and software. If implemented as a computer-implemented apparatus, the present invention is implemented using means for performing all of the steps and functions described above.
[0117] The present invention can be included in an article of manufacture (e.g., one or more computer program products) having, for instance, computer useable media. The media has embodied therein, for instance, computer readable program code means for providing and facilitating the mechanisms of the present invention. The article of manufacture can be included as part of a computer system or sold separately.
[0118] It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention.
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A Jam Factor rating is provided that represents the status along a specified route. A free flow travel time is calculated for the specified route. An estimated travel time is calculated for the specified route by considering traffic conditions along the specified route. A delay assessment is determined by comparing the estimated total travel time to the free flow travel time. The Jam Factor rating is based on the delay assessment.
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a semiconductor device and a wire bonding method in which a first bonding point and second bonding point are connected by a wire and more particularly to a semiconductor device that has a low wire loop shape and to a method for manufacturing such a semiconductor device.
[0003] 2. Prior Art
[0004] In wire bonding, when slack occurs in a wire that connects a first bonding point and a second bonding point, the wire contacts the die that causes short-circuiting. Conventionally, in order to prevent this, a press-bonded ball is first formed by press-bonding a ball to the first bonding point, then a neck height portion that extends upward is formed on the press-bonded ball, and a bent portion (kink) is formed at the upper end of this neck height portion. This method is disclosed in, for example, Japanese Patent Application Laid-Open (Kokai) No. H 10-189641.
[0005] In methods of the prior art, since a neck height portion is formed on the press-bonded ball, the resulting wire loop is inevitably high. In recent years, though there are strong demands that semiconductor devices be made smaller and thinner, with prior art methods, such demands are not sufficiently satisfied.
SUMMARY OF THE INVENTION
[0006] Accordingly, the object of the present invention is to provide a semiconductor device and a wire bonding method that form a low wire loop.
[0007] The above object is accomplished by a unique structure of the present invention for a semiconductor device in which a first bonding point and a second bonding point are connected by a wire loop, and in the present invention, the wire loop is comprised of:
a circular arc portion that extends in a shape of a circular arc from the first bonding point, an inclined portion that extends to the second bonding point from the circular arc portion, and a bent portion formed between the circular arc portion and the inclined portion.
[0011] The above object is accomplished by another unique structure of the present invention for a semiconductor device in which a first bonding point and a second bonding point are connected by a wire loop, and in the present invention, the wire loop is comprised of:
a circular arc portion that extends in a shape of a circular arc from the first bonding point, a horizontal portion that extends horizontally from the circular arc portion, an inclined portion that extends to the second bonding point from the horizontal portion, and bent portions respectively formed between the circular arc portion and the horizontal portion and between the horizontal portion and the inclined portion.
[0016] The above object is accomplished by a series of unique steps of the present invention for a wire bonding method that connects a first bonding point and a second bonding point by a wire, and in the present invention, the method comprises sequentially:
a step that press-bonds a ball formed on a tip end of a wire to a first bonding point, thus forming a press-bonded ball, a step that slightly raises a capillary, moves the capillary toward a second bonding point, and then lowers the capillary by an amount that is smaller than an amount in which the capillary was raised, and a step that raises the capillary to allow the wire to be paid out of the capillary and moves the capillary toward a second bonding point, thus connecting the wire to the second bonding point.
[0020] The above object is accomplished by another series of unique steps of the present invention for a wire bonding method that connects a first bonding point and a second bonding point by a wire, and in the present invention, the method comprises sequentially:
a step that press-bonds a ball formed on a tip end of a wire to a first bonding point, thus forming a press-bonded ball, a step that slightly raises a capillary, moves the capillary toward a second bonding point, and then lowers the capillary by an amount that is smaller than an amount in which the capillary was raised, a step that raises the capillary and then performs at least once a reverse operation in which the capillary is moved in a direction opposite from the second bonding point, and a step that raises the capillary to allow the wire to be paid out of the capillary and moves the capillary toward the second bonding point, thus connecting the wire to the second bonding point.
[0025] Since the portion of the wire that extends from the first bonding point is a circular arc portion, the height of this circular arc portion is lower than that of a conventional neck height portion. Accordingly, in the present invention, an extremely low wire loop is formed. Furthermore, since a bent portion is formed between the circular arc portion and the inclined portion, no slack occurs in the wire that is connected between the first bonding point and the second bonding point.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIGS. 1 ( a ) through 1 ( f ) show the steps of the first embodiment of the wire bonding method of the present invention; and
[0027] FIGS. 2 ( a ) through 2 ( e ) show the steps of the second embodiment of the wire bonding method of the present invention, the step of FIG. 2 ( a ) following the step of FIG. 1 ( c ).
DETAILED DESCRIPTION OF THE INVENTION
[0028] A first embodiment of the semiconductor device of the present invention will be described with reference to FIG. 1 ( f ).
[0029] The wire loop (or the wire loop shape) in which the first bonding point A and second bonding point B are connected by a wire 4 includes a circular arc portion 31 , which extends in the shape of a circular arc from the first bonding point A, and an inclined portion 33 , which extends from this circular arc portion 31 to the second bonding point B. A bent portion 21 is formed between the circular arc portion 31 and the inclined portion 33 .
[0030] Since the portion of the wire that extends from the first bonding point A is thus a circular arc portion 31 , the height of the circular arc portion 31 is lower than that of a conventional neck height portion. Thus, the wire loop is extremely low. Since the bent portion 21 is formed between the circular arc portion 31 and the inclined portion 33 , no slack occurs in the wire 4 that is connected between the first bonding point A and second bonding point B.
[0031] Next, a first embodiment of the wire bonding method of the present invention that is used to obtain a semiconductor device such as that shown in FIG. 1 ( f ) will be described with reference to FIG. 1 .
[0032] As shown in FIG. 1 ( f ), a die 3 on which an electrode pad 2 is formed is mounted on a circuit board 1 consisting of a lead frame or a board such as a ceramic substrate or printed board, etc. A first bonding point A on such an electrode pad 2 and second bonding point B such as wiring or a lead on the circuit board 1 are electrically connected by a wire 4 .
[0033] First, as shown in FIG. 1 ( a ), with a damper (not shown in the drawings) that holds the wire 4 in an open state, a capillary 5 is lowered so that a ball formed on the tip end of the wire 4 is bonded to the first bonding point A, thus forming a press-bonded ball 11 .
[0034] The capillary 5 is then slightly raised to point C, and the wire 4 is paid out of the capillary 5 .
[0035] Next, as shown in FIG. 1 ( b ), the capillary 5 is moved horizontally to point D in the direction of the second bonding point B.
[0036] Then, as shown in FIG. 1 ( c ), the capillary is lowered to point E by an amount that is smaller than the amount of the above-described raising. As a result of the step shown in this FIG. 1 ( c ), a strong bent portion 21 is formed in the portion of the wire that is located slightly above the press-bonded ball 11 .
[0037] Next, as shown in FIG. 1 ( d ), the capillary 5 is raised to point F by an amount that corresponds to the length of wire that is to be connected between the first bonding point A and the second bonding point B, and the wire 4 is paid out of the capillary 5 .
[0038] Afterward, an operation that is the same as that performed in a conventional method is performed. More specifically, as shown in FIG. 1 ( e ), the capillary 5 is caused to make a circular arc motion or is caused to make a circular arc motion and is then lowered, so that the capillary 5 is positioned at the second bonding point B, and the wire 4 is bonded to the second bonding point B.
[0039] Next, the damper (not shown in the drawings) and the capillary 5 are both raised, and the damper is closed at an intermediate point during this raising movement, so that the wire 4 is cut from the root portion of the second bonding point B as shown in FIG. 1 ( f ). As a result, the first bonding point A and second bonding point B are electrically connected.
[0040] Conventionally, a bent portion is formed by performing a reverse operation on a portion of the wire 4 located above the press-bonded ball 11 . Accordingly, a neck height portion that rises upward from the press-bonded ball 11 is formed. However, in the shown embodiment, the capillary 5 is moved toward the second bonding point B as shown in Fig. 1 ( b ), and the capillary 5 is then lowered so that a bent portion 21 is formed as shown in FIG. 1 ( c ). Accordingly, the bending direction of the bent portion 21 is the opposite of that in a conventional method. Consequently, when the capillary 5 is moved to a point above the second bonding point B as shown in FIGS. 1 ( d ) through 1 ( e ), the portion of the wire between the press-bonded ball 11 and the bent portion 21 forms a circular arc portion 31 , and the height of this circular arc portion is lower than that of a conventional neck height portion, and the wire loop is extremely low. Furthermore, since the bent portion 21 is formed by lowering the capillary 5 as shown in FIG. 1 ( c ), a strong bent portion 21 is formed, and no slack occurs in the wire 4 that is connected between the first bonding point A and second bonding point B.
[0041] A second embodiment of the semiconductor device of the present invention will be described with reference to FIG. 2 ( e ).
[0042] Here, the wire loop (or the shape of the wire loop) in which the first bonding point A and second bonding point B are connected by a wire 4 includes a circular arc portion 31 that extends from the first bonding point A, a horizontal portion 32 that extends horizontally from this circular arc portion 31 , and an inclined portion that extends to the second bonding point B from this horizontal portion 32 . Bent portions 21 and 22 are respectively formed between the circular arc portion 31 and the horizontal portion 32 and between the horizontal portion 32 and the inclined portion 33 .
[0043] In addition to the advantages of the above-described embodiment, the second embodiment also provides advantages. Especially, since the bent portion 22 is formed at an intermediate point of the wire loop, the portion of the wire between the bent portion 21 and the bent portion 22 is a substantially horizontal to be a horizontal portion 32 . As a result of the existence of this horizontal portion 32 , contact of the wire 4 with the die 3 is prevented even if, for example, the die 3 should extend as indicated by the two-dot chain line so that the distance between the first bonding point A and the end portion of the die 3 is long; Furthermore, sagging of the wire loop is reduced even in cases where the distance between the first bonding point A and the second bonding point B is long. Accordingly, such a horizontal portion 32 is effective.
[0044] Next, a second embodiment of the wire bonding method of the present invention that produces a semiconductor device such as that shown in FIG. 2 ( e ) will be described with reference to FIGS. 2 ( a ) through 2 ( e ). The same reference numerals are assigned to members or portions that are the same as in FIGS. 1 ( a ) through 1 ( f ) or that correspond to members or portions in FIGS. 1 ( a ) through 1 ( f ), and a detailed description of such members or portions is omitted. In this embodiment, as seen from FIG. 2 ( e ), a bent portion 22 is formed at an intermediate point on the wire 4 .
[0045] First, a bent portion 21 is formed at a point located slightly above the press-bonded ball 11 by the steps shown in FIGS. 1 ( a ) through 1 ( c ).
[0046] Next, as shown in FIG. 2 ( a ), the capillary 5 is raised to point G by an amount that corresponds to the length of the horizontal portion 32 shown in FIG. 2 ( e ).
[0047] Then, as shown in FIG. 2 ( b ), a reverse operation is performed in which the capillary 5 is moved in a circular arc to point H in the opposite direction from the second bonding point B and is lowered. As a result, the wire 4 is placed in an inclined state, and a bent portion 22 is formed.
[0048] Next, as shown in FIG. 2 ( c ), the capillary 5 is raised to point I by an amount that corresponds to the length of the inclined portion 33 shown in FIG. 2 ( e ). Subsequently, the same operations as those shown in FIGS. 1 ( e ) and 1 ( f ) are performed, so that the wire 4 is bonded to the second bonding point B as shown in FIGS. 2 ( d ) and 2 ( e ).
[0049] In the above embodiment shown in FIG. 2 , a single bent portion 22 is formed in the portion of the wire 4 located between the bent portion 21 and the second bonding point B. However, it is also possible to perform two or more reverse operations so that two or more bent portions are formed.
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A wire bonding method that connects a first bonding point and a second bonding point by a wire, the method including a step that press-bonds a ball formed on a tip end of a wire to a first bonding point, thus forming a press-bonded ball; a step that slightly raises a capillary, moves the capillary toward a second bonding point and then lowers the capillary by an amount that is smaller than an amount in which the capillary was raised, and a step that raises the capillary to allow the wire to be paid out of the capillary and moves the capillary toward a second bonding point, thus connecting the wire to the second bonding point.
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RELATED APPLICATIONS
This application claims all the benefit and priority under 35 USC 119(e) to U.S. Provisional Patent Application No. 60/268,492 filed on Apr. 26, 2001 and 60/309,527 filed on Aug. 1, 2001.
BACKGROUND OF THE INVENTION
1. Technical Field
The subject invention relates generally to cooling systems for internal combustion engines of automotive vehicles and, more particularly, to an electromagnetically controlled thermostat valve for controlling the flow of liquid coolant to a radiator.
2. Description of the Related Art
An internal combustion engine that powers an automobile normally has a liquid cooling system for removing waste heat generated by the combustion process in the engine. Such a cooling system may comprise a pump operated by the engine, a radiator, and a thermostat valve. As the pump circulates liquid coolant through the system, engine heat is transferred to the coolant passing through engine coolant passages. When the engine has reached a predetermined operating temperature, the thermostat valve opens to allow coolant to flow through the radiator where heat is transferred from the coolant to ambient air passing across exterior surfaces of the radiator. Hence, the thermostat valve restricts coolant flow to the radiator until the engine heats the coolant to a temperature corresponding to the operating temperature of the engine. This allows a cold engine to reach the desired operating temperature more quickly. Once the thermostat valve has fully opened, the temperature of the coolant, and hence that of the engine, can fluctuate over a range of operating temperatures determined by various factors such as the size of the radiator, the rate at which the pump pumps liquid coolant through the radiator, how the engine is being operated, and the ambient air temperature. Should the operating temperature fall below this range, the thermostat valve will once again restrict flow to the radiator in an effort to restore the operating temperature of the engine.
Most thermostat valves have bimetallic coil or wax pellet type actuators. These valves are self-contained devices that open and close according to predetermined temperature limits. They have certain disadvantageous operating characteristics, including relatively slow response times and relatively wide switching hysteresis. Such characteristics result in a wide range of temperatures over which the valve operates between closed and open positions. Hence, such thermostats exhibit relatively loose temperature regulation. Furthermore, conventional thermostats do not allow optimal control over the cooling system because they passively respond to changes in coolant temperature only. Other factors, such as actual engine temperature, engine speed, coolant flow rate, and ambient air temperature cannot be utilized when setting the operating state of such thermostats.
Active thermal management control systems increase the fuel economy of automobiles, and use an electrically-controlled flow divider, or so-called proportional thermostat valve. Existing electromagnetic thermostat valves use linear actuators to replace wax pellets found in conventional thermostats. Although this design allows control by a central computer, the valve movement is against the fluid flow direction, just like in a conventional thermostat. Therefore, the linear actuator requires a constant power supply. Furthermore, the valve only has very a limited number of configurations, which are insufficient to achieve optimal and efficient operating conditions.
An example of a proportional coolant valve that is driven by a rotary actuator is disclosed by Busato et al in U.S. Pat. No. 5,950,576. The rotary actuator of this valve has to overcome a friction torque created by a coil spring against a moving element, and hence, also requires a constant power supply.
Another disadvantage arises with both types of valve systems when debris and impurities such as iron oxide, sand or scale is present in the coolant. The debris can cause clogging or potential seizure of two surfaces that move relative to one another.
SUMMARY OF THE INVENTION
The apparatus of the present invention addresses the need for a more rapid and effective control of coolant temperature than conventional systems. To obtain high cooling efficiencies, the thermostat valve according to one aspect of the invention is controlled via a central computer by monitoring other variables in addition to coolant temperature, such as engine block temperature, engine speed, coolant flow rate, and ambient air temperature. This control is achieved with a relatively simple mechanical device that affords complete control over the amount of coolant flow that reaches the radiator. Additional benefits include minimal power consumption to operate the valve, and the ability to independently control fluid flow to the radiator or bypass valves.
The apparatus of the present invention also addresses the need for a valve that is unaffected by the level of impurities in the coolant.
BRIEF DESCRIPTION OF THE DRAWINGS
Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
FIG. 1 is an exploded orthogonal view of the thermostat valve and actuator according to the present invention;
FIG. 2 is an exploded orthogonal view similar to that shown in FIG. 1, wherein the actuator includes a DC motor with a worm gear set;
FIG. 3 is a top view of the valve and actuation components;
FIG. 4 is a cross-sectional view taken along line 4 — 4 of FIG. 3;
FIG. 5 is a detailed perspective view of the valve housing with a specially contoured inside wall;
FIG. 6 is a detailed perspective view of the sealing plate;
FIG. 7 is a detailed perspective view of the valve core;
FIG. 8 is a cross-sectional side view of the valve body and butterfly valve core whereby coolant flows to both the main passage and the bypass passage;
FIG. 9 is a cross-sectional top view of the valve body and butterfly valve core whereby coolant flows to both the main passage and the bypass passage;
FIG. 10 is a schematic graph illustrating the relationship between the throttling areas of the main port and bypass port as a function of the valve rotary angle;
FIG. 11 is a schematic graph illustrating the flow distribution between the main outlet port and the bypass port as a function of the valve rotary angle;
FIG. 12 is a cross-sectional top view of the valve body and butterfly valve core whereby coolant flows to only the bypass passage;
FIG. 13 is a cross-sectional top view of the valve body and butterfly valve core whereby coolant flows to only the main outlet passage;
FIG. 14 is a cross-sectional view of an alternative embodiment whereby the throttling openings are C-shaped;
FIG. 15 is a cross-sectional view of an alternative embodiment whereby the butterfly valve core has two circular wings;
FIG. 16 is a cross-sectional view of the proportional valve having an alternative worm gear subassembly driving mechanism;
FIG. 17 is a cross-sectional view of the worm gear subassembly of FIG. 16;
FIG. 18 is an exploded view of the worm gear subassembly of FIG. 17;
FIG. 19 is a perspective view of an alternative embodiment of the butterfly valve with cone-shaped vane flow restrictors;
FIG. 20 is a top perspective view of the alternative butterfly valve and cone-shaped vane flow restrictor seated adjacent the bypass port;
FIG. 21 is a cross-sectional view of the alternative butterfly valve and cone-shaped van flow restrictor seated in the bypass port;
FIG. 22 is an exploded perspective view of yet another alternative embodiment of a thermostat valve assembly having a failsafe mechanism;
FIG. 23 is a side view of the valve assembly of FIG. 22 in normal operating and locked position;
FIG. 24 is a perspective view of the valve assembly of FIG. 22 with the failsafe mechanism in the unlocked position;
FIG. 25 is a perspective view of the valve assembly of FIG. 22 with the butterfly valve rotated to the failsafe open position;
FIG. 26 is a cross-sectional view of the valve assembly and failsafe mechanism in the locked position; and
FIG. 27 is a cross-sectional view of the valve assembly and failsafe mechanism in the unlocked position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1 through 4, wherein like numerals indicate like or corresponding parts throughout the several views, FIG. 1 shows an electromagnetically controlled thermostat valve assembly 10 comprising a valve housing 1 , a valve core 2 , a sealing plate 3 , a cover 4 , an electric driving mechanism or actuator 5 , a valve position sensor 6 , seals 7 and 8 , and bolts 9 . Bushings or bearings may be necessary to support the valve rotary shaft, although such bushings or bearings are not illustrated. The valve position sensor 6 may not be necessary, depending on the actuation system used.
The actuator 5 can be any actuator that can overcome the load torque of valve core 2 and output valve rotary position, including, but not restricted to, DC motors, stepper motors, servomotors, gear motors, controllable rotary solenoid actuators, and linear actuators with moment arms. A cost effective actuator may be a DC motor with a worm gear set, as shown in FIG. 2 . The driving mechanism or actuator 5 shown in FIG. 2 includes a DC motor SA, worm gear SB, worm 5 C and two bushings which are not labeled. A “Hall effect” rotary position sensor 6 is mounted on the shaft of valve core 2 through a connector (not labeled). This type of actuator can maintain a required valve position without continuous power consumption because of the operating characteristics of a worm gear set. The sensor 6 measures valve position and provides feed back of the measured signals to a central controller or CPU, which provides the control strategy for controlling the rotary movement of the DC motor. Such a control system is well known and is outside the scope of the present invention.
As illustrated in FIG. 5, valve housing 1 has an inlet port 1 A, a main outlet port 1 B, a bypass outlet port 1 C and a cavity hole 1 J and a specially designed inside wall. A round counter-bore hole 1 G is used to seat the sealing plate 3 , which is detailed in FIG. 6. A hole 1 H is counter-bored down into the bottom surface 1 F for bushing the bottom part of shaft 2 G of valve core 2 , which is detailed in FIG. 7 . The inside wall of valve housing 1 has two working portions which are labeled 1 D and 1 E. The sealing plate 3 , as shown in FIG. 6, has two grooves 3 C, 3 E on surfaces 3 B and 3 D for seating seals 7 and 8 respectively. The hole surface 3 D supports the valve rotation shaft 2 G. Sealing plate 3 with seals 7 and 8 prevents coolant from entering the driving system. The valve core 2 has two throttling edges 2 A and 2 B, a top surface 2 C and bottom surface 2 D. The shaft 2 G is supported on surfaces 2 E and 2 F by bearings or bushings and transmits rotary movement and torque from driving actuator 5 to valve core 2 . The cross-sectional view shown in FIGS. 8 and 9 illustrate the assembly of the main components of the present invention.
As described earlier, the valve housing 1 has two working portions labeled 1 D and 1 E which are essential features of the present invention. The two inside wall surfaces 1 D and 1 E, and the bottom surface 1 F of valve housing 1 , together with the bottom surface 3 A of sealing plate 3 , and cylindrical end surfaces 2 A and 2 B of valve core 2 collectively form two rectangular throttling openings through which coolant can flow, as indicated by arrows shown in FIG. 9 .
At any valve position, the respective areas of two openings determine the flow distribution between the main passage outlet port 1 B and bypass outlet port 1 C. The opening area for main passage flow at a given valve angular position is defined by the height of butterfly valve core 2 and the shortest distance between end surface 2 A of valve core 2 and inside wall surface 1 D of valve housing 1 . Similarly, the opening area for bypass flow depends on the height of butterfly valve core 2 and the shortest distance between end surface 2 B of valve core 2 and inside wall surface 1 E of valve housing 1 . The working portions 1 D and 1 E of inside wall of valve housing 1 are designed such that the area of two openings varies from 0 to a saturated value, corresponding to a fully opened valve. The relationships between the throttling areas of the main port and bypass, relative to the valve rotary angle, are shown in FIG. 10 .
Sealing surfaces 1 K and 1 L allow the vanes 2 H and 2 J to seal against the housing when closing either port 1 B or 1 C. For the contour design shown in FIG. 9, the flow distribution between main port 1 B and bypass port 1 C, relative to the valve rotary angle, is shown in FIG. 11 .
FIG. 12 shows a butterfly valve position whereby the main port 1 B is fully closed and the bypass port 1 C is fully open, while FIG. 13 shows the opposite valve position, whereby the main port 1 B is fully open and the bypass port 1 C is fully closed.
In another embodiment, the concept of a specially contoured inside valve housing wall is applied to the bottom surface IF of valve housing 1 and the bottom surface 3 A of sealing plate 3 to form “C” shaped or “L” shaped throttling openings for the main port and bypass port. FIG. 14 illustrates a possible configuration with “C” shaped throttling openings and a butterfly valve core with two circular wings. Of course, different opening configurations can be achieved by designing different shapes for surfaces 1 F, 3 A, 1 D and 1 E. These specially designed surfaces form two wedging flow passages for the main output port and bypass, so that any debris present in the coolant can easily pass through them without clogging the valve.
In the case where only the inside wall of valve housing 1 has specially-designed surfaces 1 D and 1 E, wipers made of suitable soft material may be embedded in top surface 2 C and bottom surface 2 D of the valve core 2 to wipe away debris on surfaces 1 F and 3 A. Yet another solution involves designing the valve core 2 with wedge shaped top and bottom surfaces, assuming a slight leakage between those surfaces is allowable.
The degree of control over the coolant flow is much larger than in conventional systems, such that the electromagnetic thermostat is capable of more precise temperature regulation in the engine, leading to improved operating efficiencies and potentially reduced tailpipe emissions.
As stated before, sealing surfaces 1 K and 1 L allow valve vanes 2 H and 2 J to seal against the valve housing, closing either port 1 B or 1 C. However, if a driving mechanism is a worm gear set driven by a DC motor then when a control system attempts to drive the valve vanes 2 H or 2 J past their limit positions 1 K or 1 L at a sufficiently high speed, the abrupt stop of valve vane 2 H or 2 J by the sealing surface 1 K or 1 L may generate a sufficiently large impact load acting on the valve vane 2 H or 2 J, resulting in self locking of the worm gear set, which makes rotation of the valve 2 in the opposite direction difficult. In order to overcome the above-mentioned problems which may be caused by the control system or driving mechanism 5 , a damping mechanism maybe introduced into this invention.
FIG. 16 shows the cross section of the assembly of another embodiment of the proportional valve with a worm gear subassembly. FIG. 17 shows the cross-section of the worm gear sub-assembly with a clutch damping mechanism while FIG. 18 shows an exploded view of the worm gear sub-assembly. The worm gear subassembly is used to replace worm gear 5 B shown in FIG. 2 . As shown in FIG. 17, the worm gear subassembly with a clutch damping mechanism includes a clutch base 12 , a wave spring washer or a disc spring washer 14 , a retaining ring 16 , and a worm gear 5 B. The clutch base 12 is keyed to valve core 2 through the bore hole 18 with key ways and has a shaft surface 20 which provides an assembly base for the worm gear 5 B. There is a clearance between the worm gear bore hole 5 B- 1 and the shaft surface 20 of clutch base 12 . This allows a rotational degree of freedom between worm gear 5 B and clutch base 12 . One or more compressed wave spring washers or disc spring washers 14 are placed between worm gear 5 B and clutch base 12 . The recess on clutch base 12 provides space for spring 14 . Retaining ring 16 holds the worm gear 5 B in place and bears the reacting force that the compressed spring 14 exerts on worm gear 5 B.
Referring to FIG. 16, when the worm 5 C driven by a rotary actuator (DC motor) drives worm gear 5 B, the compressed spring 14 generates a drag torque acting on clutch base 12 , which drives valve core 2 . The selection of spring 14 and its pre-load ensures that the drag torque is sufficiently large to overcome the maximum load torque acting on the valve core shaft. However, the worm drive 5 B and 5 C must be able to overcome this drag torque and rotate relative to clutch base 12 when a sudden stop of valve vanes 2 H or 2 J by sealing surfaces 1 K or 1 L occurs. Such a selection and setting of spring 14 effectively prevents worm gear set 5 B and 5 C from being jammed or self locked.
In order to eliminate possible jamming of worm gear set, a spring loaded clutch is used as a damping mechanism for this embodiment of present invention. Such a damping mechanism may not be necessary if a suitable control strategy is used in the control system of the proportional valve to prevent impact from taking place. Obviously, other damping means can be used. For example, elastic materials may be attached on sealing surfaces 1 K and 1 L to reduce possible impact. Using elastic materials and corresponding structure design to replace the spring loaded clutch may be another possible option. Furthermore, hydraulic damping principle may be considered as a choice.
Referring to FIGS. 19-21, an alternative embodiment of a butterfly valve is shown at 30 . The valve 30 includes a pair of spaced apart vanes 32 , 34 extending outwardly from a valve rotation shaft 36 which is rotatably seated in the valve housing 1 as previously described. Each of the vanes 32 , 34 is a generally rectangular planar plate and each includes a cone-shaped flow restrictor 38 protruding from the center thereof. The flow restrictors 38 are position to align with and be seating in the opening formed in the main outlet port 1 B and bypass outlet port 1 C to improve the flow characteristics of the fluid through the valve assembly 10 between the open and closed positions. More specifically, a flat vane allows for a rapid increase in coolant flow within the first few degrees of valve rotation creating a nonlinear relationship between fluid flow and vane angle diminishing the valve's ability to regulate or modulate small amounts of coolant flow as the vane or valve begins to open. The addition of the cone shaped flow restrictor protrusions 38 on the back side of the vanes 32 , 34 gradually restricts the coolant flow at the extreme vane position, or in the first few degrees of vane rotation between open and closed, and therefore creates a more linear flow characteristic and better flow control in the extreme initial range of 10 degrees of vane or valve rotation. As shown in FIGS. 20 and 21, the restrictor 38 on the vane 34 gradually rotates and closes into the opening of the bypass port 1 C to gradually and uniformly open or close the port 1 C and linearly control the flow of coolant flow therethrough.
Finally, referring to FIGS. 22-27, yet another alternative embodiment of the valve assembly is shown at 50 . The valve assembly 50 includes the butterfly valve core 30 of FIG. 19 includes the pair of vanes 32 , 34 with cone-shaped flow restrictors 38 . The vanes 30 project outwardly from a hollow, cylindrical valve rotation shaft 52 . A clutch housing 54 is seated on the top portion of the valve shaft 52 for cooperative engagement with the worm gear drive assembly 5 . The clutch housing 54 has a hollow, cylindrical center 56 in mating engagement with the hollow shaft 52 . The valve assembly 50 further includes a failsafe mechanism 58 to prevent the drive assembly 5 from self-locking when the vanes are in the locked or closed position against the valve openings. More specifically, the failsafe mechanism 58 includes a cone-shaped locking key 60 slidably received in the hollow shaft 52 and capable of slidably projecting into the hollow center 56 of the clutch housing 54 . Further, the locking key 60 is rotationally keyed to the clutch housing 54 to prevent relative rotation therebetween, but freely rotatable within the hollow shaft 52 of the butterfly valve 30 . The locking key 60 includes a cylindrical hollow center bore 62 and a pair of locking tabs 64 projecting outwardly from the lower portion of the outer cylindrical wall for cooperation with the valve shaft 52 . Specifically, the valve shaft 52 includes tapered cut-out windows 66 for receiving the locking tabs 64 wherein the windows 66 retain the locking tabs 64 and prevent rotation of the locking key 60 within the valve 30 in the locked position seated in the bottom of the shaft 52 and spaced from the clutch housing 54 , as shown in FIG. 26, and allow rotation of the valve 30 around the locking key 60 in the unlocked position, as shown in FIG. 27. A coil spring 68 is seated around the locking key 60 within the hollow valve shaft 52 and compressed to bias the locking key 60 to the locked position.
The failsafe mechanism 58 further includes an actuator element 70 , which in the preferred embodiment is a wax element, seated in the hollow center bore 62 of the locking key 60 for actuating the locking key 60 between the locked and unlocked positions. The actuator 70 includes a heat activated stem 72 which stocks similar to a piston in response to a predetermined temperature. As shown in FIG. 27, when the actuator 70 is subjected to a predetermined temperature, the stem 72 extends longitudinally to engage with the locking key 60 and slide the key 60 longitudinally within the valve shaft 52 releasing the locking tabs 64 from the windows 66 and disengaging the locking key 60 from the valve 30 in the unlocked position to allow rotation of the valve 30 . The actuator 70 is enclosed within the bore 62 by a cap 74 which covers and closes the end of the locking key 60 and valve shaft 52 . The failsafe mechanism is calibrated to a temperature slightly above the normal extremes of the coolant temperature such that if the valve 30 locks in the closed position, the coolant temperature will quickly increase, causing the stem 72 to stroke and disengage the valve 30 from the locking key 60 . The coolant pressure through the inlet port 1 A will then rotate the valve 30 partially open and prevent the engine from overheating.
Having now fully described the invention, any changes can be made by one of ordinary skill in the art without departing from the scope of the invention as set forth herein.
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An improved cooling system for an internal combustion engine is disclosed. The system utilizes an electronically controlled butterfly valve to control coolant flow between the engine and a radiator, thereby maintaining the engine temperature at a substantially optimum temperature. The valve includes a valve housing having an inlet port in fluid communication with an outlet port. A valve core is seated in the housing for selectively opening and closing the outlet port. A driving mechanism is operatively coupled to the valve core for positioning the valve core between open and closed positions relative to the outlet port. A damping mechanism is coupled between the driving mechanism and the valve core for preventing the driving mechanism from locking in the open or closed position during loading of the valve core with the housing and inlet or outlet ports.
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BACKGROUND OF THE INVENTION
The present invention relates to the field of co-fired glass and/or ceramic (hereafter just ceramic) structures and, more particularly, to techniques for processing such structures so as to be able to form adherent layers of metallurgy on their surface.
Ceramic structures, usually and preferably multilayered, are used in the production of electronic substrates and devices. Many different types of structures can be used, and a few of these structures are described below. For example, a multilayered ceramic circuit substrate may comprise patterned metal layers which act as electrical conductors sandwiched between ceramic layers which act as insulators. The substrates may be designed with termination pads for attaching semiconductor chips, connector leads, capacitors, resistors, covers, etc. Interconnection between buried conductor levels can be achieved through vias formed by metal paste-filled holes in the individual glass ceramic layers formed prior to lamination, which, upon sintering, will become a sintered dense metal interconnection of metal-based conductor.
In general, conventional ceramic structures are formed from ceramic greensheets which are prepared by mixing a ceramic particulate, a catalyst (e.g., such as that disclosed in Herron, et al., U.S. Pat. No. 4,627,160), a thermoplastic polymeric binder, plasticizers and solvents. This composition is spread or cast into ceramic sheets or slips from which the solvents are subsequently volatilized to provide coherent and self-supporting flexible green sheets. After blanking, stacking and laminating, the green sheets are eventually fired at temperatures sufficient to drive off the polymeric binder resin and sinter the ceramic particulates together into a densified ceramic substrate.
The electrical conductors used in formation of the electronic substrate may be high melting point metals such as molybdenum and tungsten or a noble metal such as gold. However, it is more desirable to use a conductor having a low electrical resistance and low cost, such as copper and alloys thereof.
Use of copper-based conductors in the multilayered structures requires the use of process techniques which do not oxidize the copper during the removal of binder resins and solvents, and sintering of the ceramic particulates together into the densified ceramic substrate.
For example, a typical firing cycle consists of pyrolyzing the binder, burning the binder off in a steam ambient, typically water vapor plus hydrogen, and then replacing the steam ambient with an inert (neutral) ambient such as nitrogen and sintering the structure to its final densified state, followed by a cool down, again in an inert atmosphere such as nitrogen.
This seemingly simple firing cycle is, in fact, extraordinarily complex in nature and has taken years and large expense to achieve. It is not an understatement to say that improvements in this art come in small steps rather than in great leaps.
It would be desirable to be able to bond a copper or gold layer to the surface of the ceramic structure. Such a metal layer might serve as a capture pad, bonding pad, input/output (I/O) pad, wiring line or other use. A pervasive problem, however, is the bonding of this metal layer to the ceramic structure without oxidizing the copper patterns. Copper and gold are notoriously deficient in adhering to ceramic structures under these kinds of sintering conditions. Obviously, an insufficiently bonded metal layer would suffer delamination during the bonding process or in use.
The art is replete with numerous metallurgies and techniques utilized to achieve an adherent metal layer on a ceramic surface.
Flaitz et al. U.S. Pat. No. 4,764,341 discloses the bonding of, for example, a nickel layer to an oxide ceramic by interposing a ternary oxide of the metal to be joined which, for this example, is NiAl 2 O 4 . The firing cycle is adjusted so that the nickel layer does not form nickel oxide and yet it is sufficiently oxidative to ensure the removal of carbon residue from the polymeric binder. The end result is nickel bonded to the NiAl 2 O 4 which, in turn, is bonded to the oxide ceramic.
Chance et al. U.S. patent application Ser. No. 929975, filed Nov. 12, 1986, "Method For Producing High Density Multilayered Glass-Ceramic Structures With Metallic Based Conductors", now abandoned but published in Japan on May 12, 1988, as J89050120-B, discloses the bonding of nickel pads to a glass-ceramic material during the firing cycle. A key element of the process is the oxidizing of the nickel pad during the crystallization segment of the firing cycle. The NiO film causes the nickel pad to bond to the glass-ceramic material. Thereafter, the NiO film may be removed by chemical means or by a reducing ambient. This latter process step, however, risks reducing the NiO bonds the nickel pad to the glass-ceramic material with the consequence that delamination of the nickel pads may occur.
Nakatani et al. U.S. Pat. No. 4,863,683 discloses a glass-ceramic substrate having an oxide paste, e.g., NiO, which during the firing cycle is reduced to the base metal, nickel in this case. The remainder of the firing cycle is completed without oxidizing the base metal.
deBruin et al. U.S. Pat. No. 4,050,956 discloses the bonding of certain metals, including copper, nickel and gold, to a refractory oxide ceramic wherein the metal and ceramic are placed in an abutting relationship and then fired in air. Ebata et al. U.S. Pat. No. 4,631,099 similarly discloses joining copper or a copper alloy to an oxide ceramic by placing them in abutting contact and then firing in an oxidative atmosphere.
Larry U.S. Pat. No. 3,854,957 discloses a metallizing paste consisting of noble metals and NiO applied to a ceramic substrate. The firing atmosphere is not specified. The NiO is added to increase the adhesion of the paste to the ceramic substrate.
The disclosure of all of the previous references are incorporated by reference herein.
Notwithstanding the prior art, there still remains a need to bond a metal layer to a ceramic structure under conditions which are non-oxidizing to the copper patterns in the ceramic structure.
Accordingly, it is an object of the invention to form an adherent layer of metal on a ceramic structure without causing oxidation of the internal copper patterns.
It is another object of the invention to form a copper, nickel or gold layer on the surface of a ceramic structure without causing oxidation of the internal copper patterns.
It is yet another object of the present invention to form such a copper, nickel or gold layer which is adherent and will not delaminate during bonding processes or in use.
BRIEF SUMMARY OF THE INVENTION
These and other objects of the invention have been achieved by providing, according to one aspect of the invention, a method of forming an adherent layer of metallurgy on a ceramic substrate comprising the steps of:
obtaining a green ceramic body comprising a ceramic material containing at least 5 weight percent of MgO, a polymeric binder and copper metallurgy patterns within said ceramic body;
forming a layer of nickel-containing metallurgy on said ceramic body;
sintering said ceramic body through a sintering cycle comprising the steps of:
(a) a pyrolysis segment to pyrolyze said polymeric binder;
(b) a binder burnoff segment conducted at a first temperature and in a steam atmosphere wherein said atmosphere is sufficient to burn off said binder without oxidizing said copper metallurgy; and
(c) a densification and, in some cases, crystallization segment conducted at a second temperature higher than said first temperature and in a steam atmosphere, said steam atmosphere selected to meet the following requirements:
a partial pressure of oxygen less than that necessary to satisfy the equilibrium equation 4Cu+O 2 =2Cu 2 O; and a partial pressure of oxygen less than or equal to that necessary to satisfy the equilibrium equation 2Ni+O 2 =2NiO.
According to another aspect of the invention, there is provided a method of forming an adherent layer of metallurgy on a ceramic substrate comprising the steps of:
obtaining a green ceramic body comprising a ceramic material containing NiO, a polymeric binder and copper metallurgy patterns within said ceramic body;
forming a layer of surface metallurgy on said ceramic body, said surface metallurgy selected from the group consisting of copper and gold;
sintering said ceramic body through a sintering cycle comprising the steps of:
(a) a pyrolysis segment to pyrolyze said polymeric binder;
(b) a binder burnoff segment conducted at a first temperature and in a steam atmosphere wherein said atmosphere is sufficient to burn off said binder without oxidizing said copper metallurgy patterns; and
(c) a densification and, in some cases, crystallization segment conducted at a second temperature higher than said first temperature and in a steam atmosphere, said steam atmosphere selected to meet the following requirements:
a partial pressure of oxygen less than that necessary to satisfy the equilibrium equation 4Cu+O 2 =2Cu 2 O; and a partial pressure of oxygen less than that necessary to satisfy the equilibrium equation 2Ni+O 2 =2NiO for nickel in said surface metallurgy.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial cross-section of a ceramic structure having an adherent layer of nickel according to the invention.
FIG. 2 is a partial cross-section of a ceramic structure having an adherent layer of copper or gold according to the invention.
FIG. 3 is a thermodynamics chart for the reaction of nickel and copper with oxygen.
FIG. 4 is a diagram of a typical firing cycle to achieve the adherent metal layers according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the figures in more detail, and particularly referring to FIG. 1, there is shown a ceramic structure 10. For purposes of the present invention, it will be assumed that the ceramic structure is a dielectric substrate for electronic applications. It should be understood, however, that such a ceramic structure has uses other than that described here and that those other uses are contemplated within the scope of the present invention.
The ceramic structure 10 comprises a ceramic body 11 and may have a plurality of vias 12. The vias may be, for example, copper or gold. It is desirable to be able to bond an adherent layer of metallurgy on the surface 14 of ceramic structure 10. This adherent layer of metallurgy may be, for example, a capture pad 16 in communication with vias 12 or wiring line 18. According to a first aspect of the invention, the adherent layer of metallurgy is a nickel-containing metallurgy. It should be understood that "nickel-containing" means unalloyed nickel as well as alloys with nickel wherein nickel is not the primary constituent. Additionally, nickel oxide may be substituted for the unalloyed nickel or the nickel in the alloys. Once the adherent layer of metallurgy is formed on the ceramic structure 10, then it is an easy task to further deposit additional layers of metallurgy. Thus, once the nickel-containing adherent layer of metallurgy is formed, then copper (or any other metal of low resistivity) may be easily joined to it. The essence of the invention is getting the nickel or nickel-containing alloy to join to the surface 14 of the ceramic structure 10.
The ceramic structure 10 may be made in the following manner. According to one aspect of the invention, a green ceramic body is formed, preferably by the tape casting methods discussed previously. The ceramic material that makes up the ceramic body should contain at least about 5 weight percent of MgO. The reason for this addition of MgO will become apparent hereafter. The green ceramic body also has copper metallurgy patterns within the body. Copper, of course, is preferred because of its low resistivity. Preferred ceramic materials include the spodumene and cordierite glass ceramic materials of Kumar et al. U.S. Pat. No. 4,301,324, the disclosure of which is incorporated by reference herein. Such materials may have about 18 to 25 percent of MgO. Other ceramic materials include mullite, Al 2 O 3 +glass, borosilicate glass with MgO addition and other glass ceramics.
Thereafter, a layer of nickel-containing metallurgy is formed on the surface of the green ceramic body. Such a layer may be formed by screening a paste which includes the nickel-containing metallurgy.
Now, the green ceramic body is sintered. Referring now to FIG. 4, the sintering cycle begins with pyrolysis which pyrolyzes the polymeric binder in the green ceramic body. The next step is binder burnoff which is conducted in a steam atmosphere. The binder burnoff is conducted in an atmosphere which is sufficient to burn off the remains of the polymeric binder without, however, oxidizing the copper metallurgy. Binder burnoff is conducted at a temperature which is less than that necessary to cause densification of the ceramic material. For the materials indicated above, the binder burnoff temperature is in the range of 690 to 850 degrees Centigrade. While generally not necessary, it is preferred to change the atmosphere after binder burnoff to nitrogen or forming gas (forming gas is a mixture of nitrogen and hydrogen). If nickel oxide is used, then forming gas must be used after binder burnoff to reduce the nickel oxide to nickel.
The invention will now be discussed with respect to FIG. 3 which illustrates the thermodynamic equilibria for the oxides of nickel and copper. Line 1 on the chart gives the equilibrium conditions for the formation of Cu 2 O. For a given temperature and partial pressure of oxygen, Cu 2 O will form above this line but not below it. Line 6 gives the equilibrium condition for the burning off of carbon. Above this line, carbon will burn off as CO 2 . Binder burnoff must take place between these two lines since above line 1, there will be detrimental oxidation of copper (which can compromise the mechanical integrity of the ceramic structure and the electrical conductivity of the copper) while below line 6, there will be insufficient burnoff of the pyrolysis products, thereby adversely affecting the electrical properties of the substrate. Kinetics dictates that binder burnoff occurs as closely as possible to the copper equilibrium line without going over it.
Also shown on FIG. 3 are various equilibrium conditions for the formation of nickel oxides. The equilibrium between analloyed Ni and NiO is given by line 4. It can be seen that this line is situated between carbon oxidation and copper oxidation. To avoid nickel oxidation during binder burnoff, the partial pressure of oxygen must be below the line that describes the Ni/NiO equilibrium. If it is assumed that binder burnoff occurs below this line 4, then NiO will not form. During the optional drying step that follows, nitrogen may be used. Since nickel oxidation is not fatal at this point in the process, binder burnoff may take place above the Ni/NiO line 4 to shorten the binder burnoff time. In the subsequent drying step, forming gas may be used to reduce the NiO to nickel.
Above the Ni/NiO line for unalloyed nickel (line 4) are lines 2 and 3 that describe the equilibrium between nickel and its oxide for nickel alloyed with copper wherein there is either 5 to 10 atom percent nickel in the alloy. As is apparent from FIG. 3, the equilibrium between nickel and its oxide for a copper-nickel alloy is at a higher oxygen partial pressure than for unalloyed nickel, indicating that copper-nickel alloys may undergo binder burnoff at a higher partial pressure of oxygen without causing oxidation of the alloy.
Similar equilibria may be described for gold-nickel alloys.
It is preferred that the amount of nickel in the copper-nickel or gold-nickel alloys be limited to a maximum of 10 atom percent. Higher percentages of nickel would adversely affect the conductivity of the metallurgy. There must be a minimum of at least 1 atom percent to achieve the efficacious results of the invention.
After binder burnoff, the ceramic body next undergoes densification and, in some cases, crystallization which occurs at a higher temperature, typically in the range of 900 to 1000 degrees Centigrade for the materials indicated above. Crystallization will not always occur since some materials, such as the glass ceramics, undergo crystallization while other materials, such as alumina and glass, do not crystallize during sintering. During this segment of the firing cycle, it is essential that NiO not form. Without the formation of NiO, it would appear that there can be no forming of an adherent layer of metallurgy on the ceramic body since nickel in the metallic state does not bond to ceramic materials. The inventors have discovered, however, that when the partial pressure of oxygen and temperature are adjusted so as to be near, but below, the Ni/NiO line for unalloyed nickel (line 4) or below the Ni/NiO line for alloys containing nickel (lines 2 and 3), there is a reaction between the ceramic body and the nickel-containing metallurgy which causes the nickel-containing metallurgy to be bonded to the ceramic material.
While not wishing to be held to any particular theory, it is believed that an interfacial layer of nickel oxide solid solution forms between the surface layer of nickel-containing metallurgy and the ceramic material. This would be true whether the nickel-containing metallurgy is unalloyed nickel, a copper/nickel alloy, or a gold/nickel alloy. For example, line 5 represents the Ni/NiO equilibrium for unalloyed Ni when the NiO is dissolved in cordierite at a thermodynamic activity of 0.1 (a NiO =0.1). Similarly, line 4 also describes equilibrium conditions for a copper/nickel alloy (10 atom percent Ni) when the NiO is dissolved in cordierite at a thermodynamic activity of 0.1 (a NiO =0.1). As can be seen, NiO forms and dissolves in the cordierite at a lower partial pressure of oxygen than for the base metal. Accordingly, it is expected by the inventors that NiO at a reduced activity will form at the interface between the ceramic body and the nickel-containing metallurgy even though the atmospheric conditions are insufficient to oxidize the nickel-containing metallurgy to form pure NiO.
The interfacial layer then goes into solution in the ceramic material so as to bond the nickel-containing metallurgy layer to the ceramic body. The reason for this is as follows. The inventors have discovered that NiO can readily substitute for the MgO in the ceramic material. Thus, the NiO that forms at the interface goes into solution in the ceramic material. It is thus important that MgO be present in the ceramic material.
Referring now to FIG. 2, the second aspect of the invention will now be discussed. As shown therein, there is a ceramic substrate generally indicated by 30 which may have a plurality of vias 32. The vias may be, for example, gold or copper. The ceramic substrate 30 includes a green ceramic body 31 having a layer of metallurgy 36, 38 formed on the surface 34 thereof. Surface metallurgy 36 may be a capture pad and surface metallurgy 38 may be a wiring line. Other forms of surface metallurgy are also contemplated within the scope of the invention.
The green ceramic body 31 comprises a ceramic material, a polymeric material and copper metallurgy patterns within the ceramic body. The green ceramic body 31 is preferably made by the tape casting method as discussed previously. The ceramic material is, preferably, the spodumene or cordierite glass ceramic materials discussed previously. While these materials normally contain some MgO, the presence of MgO is not necessary for this aspect of the invention.
The green ceramic body 31 does include, however, an addition of NiO which may be present in the ceramic material itself or may be added as discrete NiO particles to the slurry during the casting of the green sheets. (Having the NiO dispersed in the ceramic material may be also advantageous for toughening the ceramic.) As shown in FIG. 2, the NiO 40 is dispersed throughout the ceramic body 31; however, it is only necessary to have the NiO near the outer surfaces of the ceramic body 31 in order to achieve the objects of the invention. The ceramic material preferably comprises about 0.5 to 30 weight percent of NiO. More preferably, there should be a minimum of 3 weight percent of NiO present.
The surface metallurgy 36, 38 comprises copper or gold. Normally, copper or gold will not adhere to ceramic materials. During the sintering according to the present invention, however, the copper or gold becomes an adherent layer of metallurgy.
The sintering cycle proceeds as before with the following qualifications. When the right temperature and oxidative conditions are present, the nickel oxide in the ceramic body will cause a bond to be formed between the surface layer of metallurgy and the ceramic body. Referring again to FIG. 3, above the Ni/NiO equilibrium line (line 4) for unalloyed nickel are the equilibrium lines for nickel in a copper/nickel alloy (lines 2 and 3). Shown are the lines for copper/nickel alloys containing 5 and 10 atom percent nickel. The particular alloy that is formed is a function of the amount of NiO in the ceramic body and the oxygen partial pressure. During binder burnoff, it is necessary to have the partial pressure of oxygen below that for the oxidation of copper. At this point in the sintering cycle, an interfacial reaction will occur between the ceramic material and the surface metallurgy. The NiO in the ceramic material will reduce to nickel and form an alloy with the surface metallurgy. Thus, this second aspect of the invention is the reverse of the first aspect of the invention. Again, the alloy that is formed will be a function of the amount of NiO in the ceramic body and the oxygen partial pressure. As shown in FIG. 3, this alloy will be a copper/nickel alloy but gold/nickel alloys will form in a similar way. The particular equilibrium line chosen will dictate how much nickel in the alloy is formed.
If desired, a drying step may be inserted after binder burnoff.
Then, during densification and crystallization, the partial pressure of oxygen should be set just below the Ni/NiO equilibrium line for nickel in copper and for the particular copper/nickel alloy.
The objects and advantages of the present invention will become more apparent after referring to the following examples.
EXAMPLES
Examples I
A series of samples were prepared to demonstrate the bonding of nickel pads to a glass ceramic substrate.
Cordierite glass ceramic (having about 20 weight percent MgO) substrates were prepared by the conventional tape casting method as discussed previously. Prior to sintering, nickel pads (60 mil diameter) were screened onto the substrate. The nickel paste consisted, in weight percent, of 83% nickel and 17% organics comprising ethyl cellulose binder, solvent, surfactant and rheological modifier.
The substrates were then sintered according to the following sintering cycle. After binder pyrolysis in nitrogen, the remainder of the sintering cycle took place with an ambient consisting of 1% H 2 in steam. Binder burnoff took place at 785 degrees Centigrade and densification and crystallization were at 975 degrees Centigrade, followed by cool down to room temperature.
Thereafter, pins were soldered to the pads to test the adhesion of the pads to the substrates. Six groups of samples were tested to failure with the following results:
______________________________________Group No. Average pull strength, lbs.______________________________________1 15.22 7.83 15.34 12.55 11.36 11.1______________________________________
Average pull strength greater than 5 pounds is considered to be acceptable. The results, therefore, indicate good adhesion of the nickel pads to the glass ceramic substrates.
Examples II
Seven substrates were prepared to demonstrate the bonding of copper/nickel pads to a cordierite glass ceramic (about 20 weight percent MgO) substrate.
As in Examples I, cordierite glass ceramic substrates were prepared but, in these examples, a copper/nickel paste was screened onto the substrates to form pads. The paste consisted, in weight percent, of 70.6% copper, 8.3% nickel, 4.1% glass frit, remainder ethyl cellulose binder, solvent, surfactant and rheological modifier. Based on the solids content alone, the paste consisted, in weight percent, of 85% copper, 10% nickel and 5% glass frit.
The substrates were sintered as in Examples I except that the sintering atmosphere was more oxidative, containing only 1000 ppm (0.1%) H 2 in steam.
Pins were then soldered to the pads for the pull test. Average pin-pull strengths ranged from 16.2 to 18.5 pounds, thereby indicating good adhesion of the pads to the substrate.
Examples III
In order to demonstrate the second aspect of the invention, glass ceramic substrates were prepared having the following composition, in weight percent: 51% cordierite glass ceramic (having about 20 weight percent MgO), 5% NiO and 44% organics (polyvinyl butyral binder, solvents, plasticizers, etc.). The substrates were prepared by the conventional tape casting method. Thereafter, copper pads were screened on the substrate with a paste comprising, in weight percent, 83% copper and 17% organics.
The substrates were then sintered as indicated in the previous examples. The atmosphere during binder burnoff was 100 ppm H 2 in steam, followed by drying in nitrogen. Then, the atmosphere was switched back to steam with the atmosphere set just below the equilibrium Ni/NiO line (line 3) for nickel (10 atom percent) in copper. This corresponded to about 1000 ppm (0.1%) H 2 in steam.
Pins were then soldered to the pads to test their adhesion to the substrates. All the substrates exhibited average pin pull results of greater than 20 pounds, thereby further demonstrating the effectiveness of the present invention.
It will be apparent to those skilled in the art having regard to this disclosure that other modifications of this invention beyond those embodiments specifically described here may be made without departing from the spirit of the invention. Accordingly, such modifications are considered within the scope of the invention as limited solely by the appended claims.
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A method of forming an adherent layer of metallurgy on a ceramic substrate which includes the steps of obtaining a ceramic material containing a polymeric binder and copper metallurgy patterns within the ceramic body. In one embodiment of the invention, the ceramic body also contains MgO.
Thereafter, a surface layer of metallurgy is formed on the surface of the ceramic body. In one embodiment, the surface layer is nickel and in another embodiment, the surface layer is copper or gold.
Then, the ceramic body undergoes a sintering cycle which includes the steps of pyrolysis, binder burnoff and, lastly, densification and, in some cases, crystallization. During densification and crystallization, there is a predetermined steam atmosphere which meets the following requirements: a partial pressure of oxygen less than that necessary to satisfy the equilibrium equation 4Cu+O 2 =2Cu 2 O; and a partial pressure of oxygen less than or equal to that necessary to satisfy the equilibrium equation 2Ni+O 2 =2NiO for nickel in said surface metallurgy.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to suspended ceiling assemblies for retaining conventional ceiling tiles and more particularly pertains to a new and improved suspended ceiling assembly which is constructed entirely of wood so as to provide an aesthetically attractive ceiling structure.
2. Description of the Prior Art
Suspended ceiling assemblies for retaining conventional ceiling panels are well known in the art. Various models and designs are available, and virtually all of the commercially available assemblies function well for their intended purpose. The majority of the conventionally available suspended ceiling assemblies are formed from metallic members and are not particularly aesthetically attractive. To offset the unattractive appearance of the suspended ceiling assemblies, various manufacturers have introduced attractive and uniquely designed ceiling tiles for use with the ceiling suspension systems. However, the use of attractive ceiling tiles alone will not completely offset the unattractive appearance of the more conventional suspended ceiling support assemblies.
At least one attempt has been made to provide an aesthetically pleasing and attractive suspended ceiling assembly. In this respect, reference is made to U.S. Pat. No. 4,367,616, which issued to R. Pearson on Jan. 11, 1983, and which is directed to a wooden beam suspended ceiling assembly. In effect, the Pearson patent discloses a suspended ceiling assembly which includes a support structure made substantially out of wood for the purpose of providing the unique aesthetic appeal of a wood beam ceiling. However, the wooden beam suspended ceiling assembly of Pearson is specially designed and cut to form a complex interlocking arrangement, and the complexity of maufacture and assembly of this particular ceiling assembly makes the same somewhat economically unfeasible, as well as being substantially difficult to assemble.
Accordingly, it can be appreciated that there exists a substantial need for a new and improved aesthetically pleasing wooden beam suspended ceiling assembly which can be economically and quickly manufactured and which can be assembled in an easy and rapid manner, and in this respect, the present invention susbstantially fulfills this need.
SUMMARY OF THE INVENTION
The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a new and improved wood track suspension ceiling system that has all of the advantages of the prior art ceiling suspension systems and none of the disadvantages. In this regard, the present invention is directed to a suspended ceiling assembly for supporting a plurality of ceiling panels over a defined area, with the support structure for the ceiling panels being manufactured completely from wood. The structure of the assembly includes cross members or struts which are positionable between block-shaped connectors that may be suspended from the ceiling by hooks. The cross members are provided with upwardly extending dowels which serve to retain the ceiling panels in position, while corner and sidewall connectors also comprise notched blocks for receiving the cross members.
It is therefore an object of the present invention to provide a new and improved wood track suspension ceiling system that has all of the advantages of the prior art suspension ceiling systems and none of the disadvantages.
It is another object of the present invention to provide a new and improved wood track suspension ceiling system which may be easily and efficiently manufactured and which may be assembled and used in a rapid and easily understood manner.
It is a further object of the present invention to provide a new and improved wood track suspension ceiling system which will prove to be of a durable and rugged construction during an extended use period.
Even another object of the present invention is to provide a new and improved wood track suspension ceiling system that is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale to the consuming public, thereby making such construction economically available to the buying public.
Still yet another object of the present invention is to provide a new and improved wood track suspension ceiling system which provides in the apparatuses and methods of the prior art some of the advantages thereof, while simultaneously overcoming some of the disadvantages normally associated therewith.
An even further object of the present invention is to provide a new and improved wood track suspension ceiling system which is constructed entirely of wood so as to be aesthetically attractive.
These together with other objects of the invention, along with 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 the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of the various wooden components comprising the wood track suspension ceiling system of the present invention.
FIG. 2 is a partial side view of the system showing ceiling tiles being retained in place.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference now to the drawings and in particular to FIG. 1 thereof, a new and improved wood track suspension ceiling system embodying the principles and concepts of the present invention and generally designated by the reference numeral 10 will be described. As shown, the basic components of the system include block-shaped connectors 12, cross-extending members or struts 14, corner connectors 16 and sidewall connectors 18. These components 12, 14, 16, 18 are separably interconnectible in the manner illustrated to form retaining arrangements for conventional ceiling tiles 20 as illustrated in FIG. 2.
With respect to the construction of a center connector 12, it can be seen that the same comprises a block of wood having a plurality of notches 22 along a top portion thereof. The notches 22 are centrally positioned on each of the four sides and top portions of the block 12 and are designed to receive an extended portion 24 of a strut 14. A center portion 26 of the block 12 is unnotched and is designed to receive an upwardly extending metallic hook 28, or some other type of fastening member, which may conveniently receive conventional ceiling wire 30 as best illustrated in FIG. 2. The ceiling wire 30 is, of course, interconnected in a fixed manner between a ceiling 32 and a hook 28 so as to retain a particular block connector 12 in position. The hook 28 may be attached to a block by any conventional and known means, such as by threaded interconnection, glue, or the like. As can be appreciated, the block connectors 12 are designed to be mounted from a ceiling 32 away from the associated sidewalls and corners thereof.
With respect to the construction of the aforementioned struts 14, it will be noted that the struts are essentially elongated rectangular wooden members having the aforementioned extending connecting ends 24 which are formed by cutting notches 34 along bottom end portions thereof. The struts 14 will have the extended end portions 24 at both of its free ends, while a pair of dowels 36 may be fixedly secured along a top surface of a strut with such dowels extending vertically upwardly therefrom. The dowels 36 serve to abut against the edges of a conventional ceiling panel 20 to retain the same in position once the ceiling panel has been installed thereon.
FIG. 1 shows the sidewall connector 18 construction as being substantially a L-shaped wooden member having a notch 38 centrally positioned along an upwardly extending sidewall 40. The notch 38 is designed to receive an extended end 24 of a strut 14 in a manner clearly illustrated in FIG. 1, while the sidewall connector may be conveniently attached to a sidewall by any conventional means, to include screws, nails, glue, and the like. The sidewall connector 18 further includes a second notch 42 formed by a horizontal leg thereof with the second notch being designed to receive a further strut 14 or some other design of wooden sidewall member.
Corner connector 16 is specifically designed for use in corners and includes an outwardly extending leg portion 44 which is designed to provide a planar support surface 46 about two faces of the connector. The surface 46 is designed to receive the extended ends 24 of struts 14 in a now apparent manner, while the surface may be formed either by cutting or the fixed securing of two separate blocks of wood together.
With respect to the manner of usage of the present invention, the corner connector 16 and the sidewall connectors 18 would first be securely positioned about the periphery of a room at a height which defines the desired location of a drop ceiling. At the appropriate distances therefrom and interiorly of the sidewalls, a plurality of block connectors 12 may then be secured to a ceiling through the use of attachment wires 30 and once these are correctly positioned, the struts 14 may be dropped into position whereby their extended ends 24 engage the notches 22, 38 and surfaces 46. Once the entire support assembly is in position, conventional ceiling panels 20 may then be dropped in position through the open areas therebetween, and the upwardly extending dowels 36 serve to secure the panels in a substantially fixed engagement with the ceiling assembly 10 forming the present invention.
The average dimensions of a block connector 12 would be three inches square by one and one-half inches in height. The central area the top of each side would include the aforementioned notches 22 which would typically be one and half inches wide and three-eights inches deep. This in effect then forms a three-quarter inch square central block 26, as aforedescribed, within the center of the connector 12.
The struts 14 would have typical dimensions of three-quarter inches in thickness and one and a half inches in width, with the length of the struts then being variable, either twenty-two and a quarter inches or forty-six and one-quarter inches, as would relate to accommodating two foot square or two by four foot sections of ceiling tile. The extended ends 24 of the struts would typically be three-eighths of an inch high.
A typical corner connector 16 could be formed by cutting standard connectors into sections wherein a one-fourth section would be used for an inside corner and a three-quarter section would be used for an outside corner. A one-half section of the connector could be used at the juncture of a wall and ceiling area, thereby to form a sidewall connector 18.
The components of the wood track suspended ceiling system could be produced in various colors, such as natural stains, or could be provided unfinished for final finishing by an installer. Producing as unfinished items would then permit a precise coloration and surface treatment to be chosen by the user. Surfaces of the wood materials could also be provided with a variety of textures, grooves, or other decorative designs such as those similar to the production of more conventional picture frame materials. Even elaborate decorative designs could then be produced, such as those which would incorporate filligre or gold leaf.
While wood materials are viewed as a basic approach to production, the potential also exists for the use of other materials to form the components. Notably, the use of molded plastics is within the intent and purview of the present invention since they may be easily produced in standard colors, as well as to incorporate various decorative textures.
Elements of the wood track suspended ceiling system of the present invention would logically be sold in kit form, as well as individually as accessory items. This then permits a user to purchase a basic quantity of elements, such as might be used in an average size room, and additional elements, such as outside corners and additional struts and trim sections, could then be purchased separately in the quantity required.
With respect to the above-description then, it should be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.
Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
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A wooden suspended ceiling assembly is designed to support acoustical tiles and is constructed of a plurality of interlocking wooden members. Cross-extending wooden beams are joined together by notched connectors with the notched connectors being attachable to a conventional ceiling by hooks. The cross-extending wooden members are provided with upwardly extending dowels for positioning tiles, while sidewall and corner connectors also comprise notched wooden blocks.
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BACKGROUND OF THE INVENTION
This invention relates to rubber screens for use in a vibratory screening apparatus for ore concentrates in mines, blast furnaces, etc., which effectively prevent the blockage or clogging of the screen openings.
Conventional screens for iron ores, cokes, broken stones, and the like include knitted steel wire meshes, punched iron sheets, rubber screens, wedge wires, and polyurethane screens. These conventional screens have not proved entirely satisfactory, however, for one or more reasons described below with reference to FIGS. 1 to 4, in which FIG. 1 is a plan view of a conventional rubber screen with a feed particle thereon; FIG. 2 is a plan view showing the feed particle in FIG. 1 wedged into a screen opening; and FIGS. 3 and 4 are front elevations showing the particle wedged into opening, and about to fall through, respectively.
Woven metallic wire meshes and punched iron sheets have poor abrasion resistance, are frequently clogged which reduces their screening efficiency, and are very noisy in operation. Of the synthetic rubber and polyurethane screens, those of the type shown in FIGS. 1 to 4 include coreless rope members 2 arranged parallel to the feed direction (shown by the arrow), and cored rope members 1 arranged transverse to the particle flow. The rope members 1 have embedded tensile cores 3 with a low elongation coefficient, and the resulting screen undergoes comparatively little clogging. The flexible coreless rope members 2 have a high elongation coefficient, however, whereby particles S larger than the screen mesh frequently become wedged into a opening and gradually work through, as shown in FIG. 4. Thus, the properly sorted undersize particles that have fallen through the screen often contain a number of larger particles of undesired size. Further, in order to increase the abrasion resistance of the screen, the diameter of the rope members must be increased, which results in a decreased ratio of screen openings and a correspondingly reduced screening efficiency.
It is generally necessary to reduce the screen mounting tension in order to prevent clogging. In screens of the aforementioned type, however, when the mounting tension is low, the screen flutters and incessantly collides with the support frame mounted on the back of the screen. This causes screen or tensile member breakage, which markedly shortens the service life of the screen.
Present day rubber screens also include strong tensile member cores extending in both the transverse and parallel directions and the sorted particle diameter is more stable with such screens. Since low-elongation, high-modulus twisted wires are used as the cores, however, the tensile members tend to hold wedged feed particles firmly in place in the screen openings, which causes substantial blockage or clogging. Specifically, when the mesh size is less than 15 mm in the lateral and the longitudinal directions, respectively, a low tension mounting must be used for the screen in order to prevent such clogging, and as mentioned above such low tension causes undesirable collisions between the screen and the support frame.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a rubber screen for a vibratory screening apparatus comprises (1) first longitudinal rope members of various cross-sectional shapes arranged parallel to each other in the particle feed direction, each of said rope members composed of a tensile core member having a high elongation at break, such as twisted strands of natural or synthetic fibers or a twisted steel wire, and a flexible outer covering of plastic, rubbery elastomer, polyurethane, or the like, and (2) second rope members of various cross-sectional shapes arranged parallel to one another and transfers (lateral) to the feed direction, each of said second rope members consisting of a tensile core member having a low elongation at break, such as a steel wire or an aromatic polyamide fiber, and a flexible outer covering similar to that of the first rope members. The points of intersection between the rope members are bonded, such as by melt-bonding, to provide an integral and efficient screen unit having enhanced blockage resistance.
According to another aspect of the invention, a rubber screen for a vibratory screening apparatus comprises either:
(1) an intersecting laminate consisting of (a) two kinds of rope members of various cross-sectional shapes composed of a flexible plastic or rubber elastomer, and tensile members having different Young's moduli and elongations at break, the different rope members being used in definite proportions and arranged in definite structural units in the lateral direction, and (b) core-containing rope members of various cross-sectional shapes arranged in the longitudinal direction, each composed of a flexible plastic or rubber elastomer and an ordinary tensile member, such as embedded natural or synthetic fibers or steel wires,
(2) an intersecting laminate consisting of (a) the same rope members as in (1) (a) above arranged in the lateral direction, and (b) coreless longitudinal rope members of various cross-sectional shapes, each composed only of a flexible plastic or rubbery elastomer, or
(3) an intersecting laminate consisting of (a) longitudinally arranged rope members each composed of a mixture of the same coreless rope members as in (2) (b) above and the same core-containing rope members as in (1) (b) above, and (b) the same transversely arranged rope members as in (1) (a) above.
Again the points of intersection in each of said combinations are joined by melt-bonding or the like to provide an integral screen unit.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings;
FIGS. 1 to 4 are as described above;
FIG. 5 is a plan view showing an embodiment of the rubber screen of this invention with a feed particle wedged in a screen opening;
FIG. 6 is a front elevation of FIG. 5 showing the feed particle wedge into the screen opening;
FIG. 7 is a front elevation of FIG. 5 showing the wedged particle driven out of the screen opening;
FIG. 8 is a perspective view of a core-containing rubber screen with intersecting longitudinal and transverse rope members;
FIG. 9 is a plan view showing an intersecting arrangement of core-containing rope members;
FIGS. 10 and 13 are each plan views showing further embodiments of a rubber screen according to the invention with feed particles wedged in a screen opening;
FIG. 11 is a front elevation of FIG. 10; and
FIG. 12 is a front elevation showing the feed particle in FIG. 10 being driven out of the screen opening.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the embodiments shown in FIGS. 5 to 7, rope members 2, each consisting of a tensile member core 4, such as natural or synthetic fibers having an elongation at break of 5 to 30%, and a flexible plastic, rubber, polyurethane, or the like outer covering, are arranged parallel to one another in the feed direction as shown by the arrow. The rope members have various cross-sectional shapes, such as circular, elliptical, polygonal, or trapezoidal. Rope members 1 of the same various cross-sectional shapes, each consisting of a tensile member 3 having an elongation at break as low as 0.5 to 15%, such as steel wires or twisted strands of aromatic polyamide fibers, and the same flexible plastic rubber, polyurethane, or the like outer covering, are arranged parallel to one another either above or below the rope members 2 in a direction transverse thereto. The points of intersection are joined by melt-bonding or the like to provide an integral screen uint. As a result of the rope members 2 having a relatively high elongation, particles S larger than the screen mesh are trapped in the openings as shown in FIG. 5, and the rope members 2 temporarily deform in the feed direction. At the same time, however, only relatively slight bonding occurs in the vertical direction, and owing to the vibration of the screening apparatus, chord vibration takes place in the rope members 1. As a result, the wedged or lodged large particles S are driven upward by the chord vibration, as shown in FIG. 7, and freed from their entrapment. Thus, the blockage of the screen openings is markedly reduced, and the screening or sorting accuracy is greatly increased.
The above description has been directed to the structure and operation of a rubber screen in accordance with the first embodiment of the invention. The efficiency of such a screen will be demonstrated with referecne to the examples and test results presented below.
Example I
A screening test was performed using a rubber screen according to this invention having the specifications set forth below, and a comparison screen made of rope members composed of a steel wire tensile member core and a polyurethane outside covering, and the ratio of clogging or mesh blockage were examined. The results are shown below.
______________________________________1. Rubber screen of this invention(I) Specification of meshes: at intervals of 10mm both in the transverse and lon- gitudinal directions Size of the screen: Width (W) 3050mm Length (L) 1220mmRope members (polyurethane-covered) Elonga- Tensile tion of modulus of Rope Type of tensile the tensile diameter tensile members members (mm) members (%) (Kg/mm.sup.2)______________________________________Transverse 5 Aromatic poly- 4.2 6-6.5 × 10.sup.3or Tension amidedirection *1500 D/3 × 2Flow 5 Tetoron (poly- 18 2 × 10.sup.3direction ester) **250 D/2 × 2______________________________________(II) Material screened: Iron ore (particle diameter 0 to 35mm)(III) Vibratory screening apparatus: Triple crown screeningapparatus(IV) Clogging ratio: less than 0.3%______________________________________ *Tensile member obtained by winding two strands each strand being made by winding three filaments of 1500 denier **Tensile member obtained by winding two strands, each strand being made by winding two filaments of 250 denier.
______________________________________2. Comparison screen (I) The specification of meshes and the size of thescreen were the same as for the rubber screen of this invention.Rope members (polyurethane-covered) Elonga- Tensile tion of modulus of Rope Type of tensile the tensile diameter tensile members members (mm) members (%) (Kg/mm.sup.2)______________________________________Longitu- Steel corddinal 5 0.22 × 7 × 7 2 12-12 × 10.sup.3directionTransverse 5 Steel cord 2 12-20 × 10.sup.3direction 0.22 × 7 × 7______________________________________ (II) Material screened: same as in 1 (III) Vibratory screening apparatus: same as in 1 (IV) Clogging ratio: approximately 30%______________________________________
As the above results clearly demonstrate, the clogging ratio for the rubber screen of this invention is only approximately 1/100 that of the comparison screen, even ignoring the poor efficiency of the prior art screen.
Now, the second embodiment of the present invention will be described.
In this embodiment, there are the following types and combinations of tensile members.
Table 1______________________________________ Tensile member in the Tensile member in theNo. lateral direction longitudinal direction______________________________________1 1 type core 1 type core2 1 type core 2 types core - core3 1 type core 2 types core - coreless4 2 types core - core 1 type core5 2 types core - core 1 type coreless6 2 types core - core 2 types core - core7 2 types core - core 2 types core - coreless8 2 types core - coreless 1 type core9 2 types core - coreless 1 type coreless10 2 types core - coreless 2 types core - core11 2 types core - coreless 2 types core - coreless______________________________________
In the above table, the "core" means a core-containing rope member, and the "coreless" means a coreless rope member.
Since it is nearly impossible for the screen to function satisfactorily when only coreless rope members are used in the lateral (tension) direction, such a situation has been omitted from table 1.
On the basis of FIG. 8 which is a perspective view of a part of a polyurethane screen composed of intersecting rope members, typical combination of tensile members according to Table 1 are given in Table 2.
Table 2______________________________________Combinations of tensile membersLateralLongitudinal A.sub.1 A.sub.2 A.sub.3 A.sub.4 A.sub.5 A.sub.6 A.sub.7 A.sub.8 A.sub.9No. B.sub.1 B.sub.2 B.sub.3 B.sub.4 B.sub.5 B.sub.6 B.sub.7 B.sub.8 B.sub.9 B.sub.10 B.sub.11______________________________________ S.sub.2 S.sub.2 S.sub.2 S.sub.2 S.sub.2 S.sub.2 S.sub.2 S.sub.2 S.sub.2 K.sub.1 T.sub.1 T.sub.1 K.sub.1 T.sub.1 T.sub.1 K.sub.1 T.sub.1 T.sub.1 K.sub.1 T.sub.1 S.sub.1 K.sub.2 K.sub.2 S.sub.1 K.sub.2 K.sub.2 S.sub.1 K.sub.2 K.sub.22 T.sub.1 T.sub.1 T.sub.1 T.sub.1 T.sub.1 T.sub.1 T.sub.1 T.sub.1 T.sub.1 T.sub.1 T.sub.1 S.sub.1 S.sub.1 S.sub.1 S.sub.1 S.sub.1 S.sub.1 S.sub.1 S.sub.1 S.sub.13 K.sub.1 K.sub.1 0 K.sub.1 K.sub.1 0 K.sub.1 K.sub.1 0 K.sub.1 K.sub.1 S.sub.1 S.sub.1 T.sub.1 S.sub.1 S.sub.1 T.sub.1 S.sub.1 S.sub.1 T.sub.14 T.sub.1 T.sub.1 O O T.sub.1 T.sub.1 O O T.sub.1 T.sub.1 O S.sub.1 S.sub.1 O O S.sub.1 S.sub.1 O O S.sub.15 K.sub.2 K.sub.2 T.sub.1 T.sub.1 K.sub.2 K.sub.2 T.sub.1 T.sub.1 K.sub.2 K.sub.2 T.sub.1______________________________________ The abbreviations in Table 2 have the following meanings. A: lateral direction B: longitudinal direction S.sub.1 : steel cord (0.22 × 7 × 7) S.sub.2 : steel cord (0.175 × 7 × 4) K.sub.1 : aromatic polyamide (1500 D/3 × 2) K2: aromatic polyamide (1500 D/3 × 4) T.sub.1 : Tetoron No. 6 (polyester) O: No tensile member (coreless)
Nos. 1, 2, 3, 4 and 5 correspond to Nos. 2, 4, 3, 7 and 10 in Table 1, respectively. Referring to FIG. 9 and taking No. 2 in Table 2 as an example, the reference numeral 1 represents rope members in the lateral direction; 3, a steel cord; 3', an aromatic polyamide tensile member; and 2, rope members in the longitudinal or particle flowing directional having embedded therein a tensile member 4 made of Tetoron. FIGS. 10 to 13 are views showing the rubber screen of this invention and the stages of the screen for particles to be used therethrough. In FIG. 10, rope members 2 of various cross-sectional shapes such as circular, elliptic, polygonal or trapezoidal shapes which are composed of a Tetoron tensile member 4 having a relatively high elongation at break of 5 to 30% and a flexible plastic, rubbery elastomer, polyurethane or the like covering the outside surface of the tensile member are arranged in parallel to one another in the flow direction of the particle S. On the other hand, in the tension direction at right angles to the flow direction, core-containing rope members 1 of the same various shapes as those of the rope members in the flow direction which are composed of either an aromatic polyamide tensile member 3' having an elongation at break of as low as 0.5 to 15% or a steel cord tensile member having a low elongation and a flexible plastic, rubbery elastomer, polyurethane or the like covering the outside surface of the tensile member are arranged on or below the plane made by the rope members 2 in a direction at right angles thereto. Each of intersections of the rope members and core containing rope members is bonded or melt-bonded to provide screen.
In FIG. 10, a pair of aromatic polyamide tensile members 3' having a low elongation and a pair of rope members 2 having embedded therein the Tetoron tensile member 4 having a relatively high elongation at break of 5 to 30% will be considered. When paricle (S) having a size larger than the size of the screen opening defined by the tensile members 3' and the rope members 2 is placed on the screen, the screen opening slightly deforms to trap the particle (S) in the screen opening. However, by actuating the vibratory screening apparatus to produce secondary vibrations of different amplitudes and frequencies in the rope members 2 in the flowing direction, the trapped particle (S) is vibrated and thrown away from the opening as shown in FIG. 12. Thus, clogging of the screen opening can be prevented.
In the above embodiment, the two tensile members 3' of the rope members 1 in the tension direction are made of an aromatic polyamide. The second aspect of this invention, however, is characterized by using, in either the tension or flowing direction, 10 to 90% of rope members having a high elongation tensile member embedded therein and 90 to 10% of rope member having embedded therein a low elongation tensile member having an elongation at break of 0.5 to 15%. Thus, in one direction of the screen, low-elongation rope members and high-elongation rope members are distributed. Hence, there are boundaries between the low-elongation rope members and the high-elongation rope members in the screen openings.
FIG. 13 is a plan view showing the boundary portion of the screen opening. In this embodiment, low-elongation aromatic polyamide member 3' and low-elongation steel cord 3 are embedded in the rope members 1 in the tension direction respectively. When a particle (S) having a larger size than that of the screen opening is placed on the screen, the rope members 1 in the tension direction are neither stretched nor deformed as in the case of FIG. 10 because the tensile members 3 and 3' have low elongations at break though the values are different. On the other hand, the rope members 2 in the flowing direction are slightly deformed because of the high-elongation Tetoron tensile member 4 thereof and cause the particles (S) to be trapped in the opening. However, as in the case of FIG. 10, it is thrown away from the opening by the secondary vibration caused by the vibratory screening apparatus. Thus, the clogging of the screen openings can be reduced.
Further, for example, aromatic polyesters (such as Tetoron), or aliphatic polyamides (such as nylon 6) can be used as tensile members having a high elongation, and aromatic polyamides (such as fiber B), or steel wires can be used as tensile members having a low elongation.
The rubber screen described above is for the case of No. 2 in Table 2. In the longitudinal direction of combination No. 2, one structural unit consists of a steel cord, an aromatic polyamide yarn and an aromatic polyamide yarn in that order.
The present invention, however, is not limited to this structural unit consisting of one type tensile member and a couple of another type tensile members. According to this invention, in rope members having embedded therein two or more kinds of tensile members having different Young's moduli and elongations at break which are arranged either in the longitudinal or transverse direction, m rope members each having a low-elongation tensile member are juxtaposed with other n rope members each having embedded therein a tensile member having a high Young's modulus or a low elongation to form a structural unit containing (m + n) rope members, and a plurality of such units are repeatingly arranged in the longitudinal or transverse direction, where m is a positive integer up to 20 and n is a positive integer up to 10.
In the present invention, coreless rope members may be usde in either the longitudinal or transverse direction as shown in Nos. 3, 4 and 5 in Table 2. The coreless rope members have elongation and elasticity, but their repulsive elasticity for throwing out particles trapped in an opening by secondary vibration is poor. Accordingly, when coreless rope members are used together with core-containing members, the undersize particles which should pass through the screen openings may partially accumulate and or clogging of the screen openings may occur. In order to eliminate these disadvantages coreless rope members are combined with core-containing rope members so that the area of the coreless portion becomes only a small percentage of the entire screen area. Furthermore, due to the presence of core-containing rope members is a major proportion, the screen has sufficient repulsive elasticity.
The screening efficiency of a rubber screen according to the second aspect of the invention will be shown by the following Example (clogging test).
EXAMPLE 2
In the same way as in Example 1, a screening test was performed using a rubber screen in accordance with this invention and a comparison screen composed of rope members each having a steel wire as a tensile member covered by polyurethane and the clogging of the screen openings was examined.
______________________________________1. Rubber screen(I) Distance between rope members: 10mm both in long- itudinal and transverse direction Screen size: Width (W) 3050mm Length (L) 1220mmRope members (polyurethane-covered) Elonga- Tensile Rope tion of modulus member Type of tensile of tensile diameter tensile members members (mm) members (%) (Kg/mm.sup.2)______________________________________Tension Aromatic poly- 5 amide 4.2 6-6.5 × 10.sup.3 (1500 D/3 × 4)Flowing Aromatic poly-direction 5 amide 4.2 6-6.5 × 10.sup.3 (1500 D/3 × 4) Tetoron (250 D/2 × 2) 18 2 × 10.sup.3______________________________________(II) Material screened: iron ore (particle size 0 to 35mm)(III) Vibratory screening apparatus: Triple crown screening apparatus(IV) Clogging: less than 0.7%______________________________________
______________________________________2. Comparison screen (I) The rope member interval and the size of thescreen were the same as those of the rubber screen in1 above.Rope members (polyurethane-covered) Elonga- Tensile Diameter tion of modulus of rope Type of tensile of tensile members tensile members members (mm) members (%) (Kg/mm.sup.2)______________________________________Longi-tudinal 5 Steel cord 2 12-20 × 10.sup.3direction (0.22 × 7 × 7)Transverse 5 Steel cord 2 12-20 × 10.sup.3direction (0.22 × 7 × 7)______________________________________(II) Material screened: same as in 1 above(III) Vibratory screening apparatus: same as in 1 above(IV) Clogging: 30%______________________________________
The above results clearly shows that the clogging of the rubber screen of this invention is 1/40 that of the comparison rubber screen having only steel cords as tensile members.
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A rubber screen for a vibratory screening apparatus comprises a plurality of first parallel rope members having suitable cross sectional shapes and arranged in a particle flowing direction, each of said first rope members having a tensile member composed of a strand of filament having a high elongation at break and an organic material having flexibility and/or elasticity and covering the tensile member, and a plurality of second parallel rope members having suitable cross sectional shapes and arranged in a direction normal to the first rope members, each of the second rope members having a tensile member of a material having a low elongation at break and an organic material having flexibility and/or elasticity and covering the tensile member, each point of intersection between the first and second rope members being suitably bonded.
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FIELD OF THE INVENTION
[0001] This invention relates to reconstruction of images from raw data.
BACKGROUND
[0002] Detector arrays for imaging frequently have a large number of detector elements, each element having its own output. However, this straightforward architecture often proves problematic in practice, because detector arrays often have a large number of detector elements, and the correspondingly large number of outputs can increase cost and complexity. Multiplexing can reduce the number of channels—lowering the cost by reducing the number of connections or components used to implement the network. Accordingly, multiplexing detector array outputs (such that there are fewer outputs than detector array elements) is of great interest, and has been extensively investigated.
[0003] Time multiplexing can be employed, where pixel elements are read out sequentially over a single channel as opposed to being read out in parallel over numerous channels. However, this approach undesirably reduces the frame rate.
[0004] In general, sampling refers to any approach for creating a digital signal from an analog signal. For an imaging array, conventional sampling theory suggests that the number of samples be on the order of the number of pixels. However, if it is known a priori that the image is sparse in some domain, the number of samples required can be significantly reduced. Techniques that exploit this kind of sparsity are often referred to as compressed sensing (CS) approaches. Other terms that have been used for this general idea include compressed sampling, compressive sampling, compressive sensing, etc. However, CS approaches unfortunately tend to perform poorly in the presence of noise, which can significantly limit the practical application of CS methods.
[0005] Accordingly, some workers are considering modifications of the normal CS approach in an attempt to improve performance. One example is the work of Trzasko et al. (US 2011/0058719), where conventional image reconstruction (e.g., a low resolution image) is used to provide an estimate of the spatial support of the image. CS image reconstruction is then performed using this spatial support estimate as a priori information for the CS image reconstruction.
[0006] However, it remains challenging to realize the theoretical benefits of CS approaches in the presence of noise.
SUMMARY
[0007] CS approaches could be used for the detector array multiplexing problem, since CS theory suggests that the required number of readout channels may be much smaller than the number of detector pixels, especially for inherently sparse images such as nuclear medicine imaging or very high-speed or low-light optical imaging. However, thus far CS has not been considered for such application because of the above-described difficulties at low SNR.
[0008] We have found, surprisingly, that the theoretical advantages of CS approaches can often be realized in the presence of significant noise by following a three part process as indicated on FIG. 1 . First, a preliminary image is computed from raw data using compressed sensing (step 102 ). Here, compressed sensing is broadly regarded as any linear estimation approach that relies on a priori sparsity or finding sparse solutions to underdetermined linear systems of equations. As indicated above, the quality of this preliminary image may be poor in the presence of noise. Second, the support of the preliminary image is computed (step 104 ). Here, support is to be understood from a numerical computation perspective. Ideally, the support of an image would be all pixels having non-zero values. Realistically, the support is defined as all pixels of the image having pixel value magnitudes greater than a predetermined threshold (pixels falling below this threshold are deemed negligible). Determination of such thresholds for zero testing is commonplace in numerical computation, and is therefore not described further here. The result of this step is a support constraint—i.e., further processing takes this support estimate to be a priori support information.
[0009] The third step 106 is computing a final image from the raw data using maximum likelihood estimation combined with the support constraint. Unexpectedly, this approach has been found to provide superior results, even though it appears that substantial information is being thrown away (e.g., the relative amplitude information for all pixels in the support of the preliminary image). It is convenient to refer to the present approach as an ML-CS approach.
[0010] Here, the three steps are described separately for convenience of exposition. In practice, they may be combined. For example, a single method may be employed to provide a support estimate from raw data using compressed sensing, thereby combining steps 102 and 104 .
[0011] More specifically, an imaging system according to an embodiment of the invention can include a set of detector pixels connected to a set of output channels, where there are fewer output channels than detector pixels. Detector pixels may be any photodetector element, including but not limited to: charge coupled devices (CCD), CMOS sensors, silicon photomultipliers (SiPM), photomultiplier tubes (PMT), avalanche photodiodes (APD), and Geiger-mode APD. For example, the detector pixels can be micro-cell Geiger pixels of a silicon photomultiplier. These photodetectors may also be coupled to other optics such as lenses, image intensifiers, or scintillation crystals. Also in non-limiting example, a silicon photomultiplier is made of up individual micro-cells, and therefore each silicon photomultiplier can be configured as an imaging array. Lastly, another non-limiting example of an imaging array is an array of solid-state detectors that receive high-energy radiation in the form of X-rays and Gamma rays. These solid state detectors can have an electrode pattern deposited on a material like cadmium-zinc-telluride (CZT) solid-state high energy photon detector that defines the imaging detectors.
[0012] A processor in the system can be configured to: 1) receive raw data from the output channels, 2) compute a preliminary image from the raw data using compressed sensing, 3) compute a support of the preliminary image to provide a support constraint, and 4) compute a final image from the raw data using maximum likelihood estimation combined with the support constraint. The final image can be provided as an output. Further channel reduction can be realized by applying time multiplexing techniques to the spatially multiplexed channels. Suitable time multiplexing techniques of encoding detector signals are described in Levin, et al. (US 2010/0258731), hereby incorporated by reference in its entirety.
[0013] Similarly, a method according to an embodiment of the invention can include the following steps: 1) receiving raw data from an imaging system having fewer output channels than detector pixels, 2) computing a preliminary image from the raw data using compressed sensing, 3) computing a support of the preliminary image to provide a support constraint, 4) computing a final image from the raw data using maximum likelihood estimation combined with the support constraint, and 5) providing the final image as an output.
[0014] In preferred embodiments, a multiplexing network can be included that connects each detector pixel to distinct output channel subsets. Preferably, the multiplexing network connects each detector pixel to the same number of output channels (i.e., the multiplexing is obtained by implementing a constant weight code). The multiplexing network can include one or more distinct intermediate levels, each level having its corresponding inputs and outputs where multiplexing of the detector pixels to the output channels is provided by a combination of the multiplexing levels. For example, multiplexing N detector pixels to M output channels can proceed directly in a single N:M multiplexing layer, or in two layers (N:A multiplexing followed by A:M multiplexing), or in three layers (N:A, followed by A:B, followed by B:M) etc.
[0015] In cases where intermediate multiplexing layers are employed, it is preferred that each of the multiplexing layers connects each of its inputs to the same number of its outputs (i.e., each multiplexing layer is obtained by implementing a constant weight code). The code weight can be the same in each layer or different in some or all of the multiplexing layers.
[0016] It is also preferred that the code be sparse to minimize the number of connections between the detector pixels and the output channels. A sparse code is defined as the column entries containing zeros for more than half the entries.
[0017] Preferably, the codes corresponding to the multiplexing network have maximum sum of the distances between the output channel subsets corresponding to any two of the detector pixels. More precisely, let D be the distance between the two output channel subsets corresponding to any pair of pixels. The codes are preferably selected to maximize the sum of all D over all pairs of output channel subsets, e.g. maximize the sum of all distances between columns of the sensing matrix. In this description of an embodiment of the invention, the Hamming distance is used as the distance function. However, any distance function that satisfies the properties of a metric space distance may be used. A metric space distance function is any function that satisfies the following three properties: Symmetry, Positive-Definiteness and the Triangle inequality. Let a distance function be defined as a function F(A,B), where A and B are column vectors of a compressed sensing matrix (or any other mapping matrix). The symmetry property is expressed as F(A,B)=F(B,A). The positive-definiteness property is expressed as F(A,B)>=0, and F(A,B)=0, if and only if A=B. The triangle inequality property is expressed as F(A,C)<=F(A,B)+F(B,C) for any three points A, B, and C. These properties of metric space distance functions are well known in the art. Examples of valid metric space distance functions include, but are not limited to: Hamming distance, Euclidean distance, Chebyshev distance, Lee distance, and Block distance.
[0018] It is expected that the use of such codes in connection with detector pixel multiplexing may be useful independently of how signals are processed. Accordingly, an embodiment of the invention is an imaging system including: 1) a set of detector pixels connected to a set of output channels, where there are fewer output channels than detector pixels, and 2) a multiplexing network that connects each detector pixel to a distinct output channel subset; where the multiplexing network is configured to implement a sparse code having maximum distance between the output channel subsets corresponding to any two of the detector pixels. A preferred embodiment of the sparse code is a binary constant-weight code where the distance metric is the Hamming distance.
[0019] The present approach is compatible with light sharing, where the number of detector pixels is less than the number of scintillator crystals. Light sharing can be beneficial to increase spatial resolution without increasing the number of detector pixels.
[0020] In some case, we can assume an imaging system has an input-output relation given by y=Cx+e, where y is a raw data vector, x is a detector pixel output vector, C is the sensing matrix (C can also be referred to as the multiplexing matrix), and e is additive noise. The detector pixel output vector x can be partitioned into a signal vector s and pixel noise vector n. A noteworthy feature of this model is that it has two noise sources (i.e., n and e). Conventional image recovery approaches tend to not account properly for the pixel noise (i.e., n), and only account for the output additive noise e.
[0021] Computing the preliminary image can include computing a norm-constrained vector x 1 such that Cx 1 =y. The norm constrained vector x 1 can have minimal l 1 norm. Alternatively, the norm constrained vector x 1 can have minimal l 0 norm. Any other norm constraint suitable for CS image can also be employed, including but not limited to: minimization of penalized versions of the l 0 and l 1 norm and constrained l 0 and l 1 norm minimization. Computing the final image can include: 1) partitioning x into signal and noise vectors s and n respectively such that s corresponds to the support of x 1 and n corresponds to the negligible components of x 1 , and 2) performing maximum likelihood estimation of s.
[0022] This approach is applicable to a wide range of imaging applications, ranging from medical imaging to digital cameras. The present approach is especially beneficial for reducing the cost of high-resolution and/or high-speed imaging applications. Such applications are common in medical imaging, and include planar imaging by X-rays or nuclear medicine, magnetic resonance imaging (MRI), X-ray computed tomography (CT), positron emission tomography (PET), and single photon emission computed tomography (SPECT). This approach will also benefit three dimensional imaging such as time-of-flight cameras being developed as next generation user interfaces for game controllers and light detection and ranging (LIDAR). Other potential applications include high-speed optical imaging with digital cameras, low-light optical imaging with digital cameras, and time-of-flight imaging for medical and non-medical applications.
[0023] This approach provides significant advantages. Decoding in this manner is more robust to noise than previous methods and is computationally feasible to implement. Other noise robust methods exist but tend to be either less robust to noise and/or too computationally intensive to implement, particularly in high-resolution imaging arrays. For positron emission tomography, we have performed simulations showing that this approach can improve the SNR of the decoded signal by 3-4 times relative to conventional compressed sensing techniques on compressed sensing multiplexing topologies. The decoder can also be applied to conventional multiplexing topologies to provide a 50% decoded SNR improvement over conventional multiplexing decoders. While preserving a minimum necessary recovered signal-to-noise ratio, cost can be lowered by enabling multiplexing under noisy conditions. Compressed sensing matrices and the preferred decoder also allow our imaging system to compensate for a few “bad” pixels by improving the yield of high-resolution digital cameras or arrays of detector pixels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 shows method steps of an embodiment of the invention.
[0025] FIG. 2 shows a system according to an embodiment of the invention.
[0026] FIGS. 3 a - b show examples of cross-strip multiplexing.
[0027] FIG. 4 shows results of a comparison of the present approach to a conventional approach for l 1 norm minimization combined with cross-strip multiplexing.
[0028] FIG. 5 shows results of a comparison of the present approach to a conventional approach for l 0 norm minimization combined with cross-strip multiplexing.
[0029] FIG. 6 shows results of a comparison of the present approach to a conventional approach for l 0 norm minimization combined with discrete cosine transform multiplexing.
[0030] FIG. 7 shows an example of multiple-level multiplexing using constant-weight codes suitable for use with embodiments of the invention.
[0031] FIGS. 8 a - b show code matrices for the example of FIG. 7 .
[0032] FIG. 9 show a noise and illumination model suitable for use in connection with embodiments of the invention.
[0033] FIGS. 10 a - c show an example of three-to-two coupling for light sharing where the number of scintillation crystals is greater than the number of detector pixels.
[0034] FIGS. 11 a - b show simulated flood images for one-to-one coupling and for three-to-two coupling.
[0035] FIG. 12 shows SNR results for one-to-one coupling and for three-to-two coupling.
DETAILED DESCRIPTION
[0036] In the following sections, two specific examples of the preceding principles are considered. In the first example, the use of compressed sensing to provide a support constraint for maximum likelihood image recovery (ML-CS) is considered in connection with positron emission tomography (PET). In the second example, the use of constant-weight codes for multiplexing PET detector pixel elements is considered in connection with ML-CS image recovery.
[0000] A) Compressed Sensing (CS) to Provide a Support Constraint for maximum likelihood (ML) image recovery
A1) CS Model
[0037] In this section, we consider a PET detector built from scintillator crystal pixels that are individually coupled one-to-one to silicon photomultipliers (SiPM). A description of the symbols used to describe the mathematical model is shown in Table 1.
[0000]
TABLE 1
Description of Symbols
Symbol
Description
x
d × 1 SiPM analog output signal vector
y
m × 1 digital channel signal vector
s
s × 1 sparse digital channel signal
vector
n
(d − s) × 1 multiplexed noise vector
e
m × 1 channel noise vector
C
m × d multiplexing weight coefficients
P
m × d permutation matrix
A
m × s map of sparse signal components
B
m × (s − d) map of noise
[0038] Compressed sensing is especially interesting for application to PET imaging because PET detector signals have a sparse representation in the natural basis. The natural basis corresponds to the pixels of a 2-D detector array. For PET, most of the signal for any annihilation photon is concentrated in very few detector pixels. CS employs non-adaptive linear projections that preserve the underlying signal information at a lower sampling rate than Shannon-Nyquist theory. From these projections, optimization algorithms can be used to decode the original set of detector signals.
[0039] Each detector block forms a 2-D array of pixels. Let the d individual SiPM pixels of the detector block be denoted by a d by 1 vector x. Multiplexed detector readouts can be used to read this 2-D array of SiPM pixels as shown in FIG. 2 .
[0040] In this example, a set of SiPM detector pixels 202 is coupled to a set of output channels 206 with a multiplexing network 204 . There are fewer output channels than detector pixels. The multiplexing network can provide weighted sums of the detector pixel signals as output channels by various analog and/or digital methods. Preferably, analog methods such as resistive or capacitive networks are employed. The coefficients of the weights are represented in the matrix C. The vector y is the vector of output channel signals. Preferably, each output channel is digitized by an analog-to-digital converter (A/D). The output channels 206 are provided as inputs to a processor 208 which implements various methods as described below. Practice of the invention does not depend critically on whether processor 208 is implemented in hardware, software, or any combination thereof.
[0041] Let the number of readout channels m of the detector be denoted by the m by 1 vector y. Then we may describe the detector readout as
[0000]
y=Cx+e
[0000] where the matrix C is the m×d sensing matrix and e is a random measurement noise vector.
[0042] Because x is already sparse in the 2-D spatial domain, there is no need for a sparsifying basis representation. In compressed sensing theory, C must satisfy the restricted isometry property, as is known in the art. By Shannon-Nyquist sampling theory, the number of readout channels m=d, which corresponds to non-multiplexed readout with one readout channel per SiPM detector pixel. From CS theory, it is known that only m≧2s readout channels are needed where s≦d/2 is the desired maximum number of photon events that can be resolved in a single detector block within a selected time window. For coincidence detection, typically s=2 and by CS theory, an entire PET system could be theoretically compressed to only 4 readout channels.
[0043] The d SiPM pixel signals can be decoded by l 0 norm minimization
[0000] {circumflex over (x)} 1 =arg min∥ x′∥ 1 ,y=Cx′. (P0)
[0000] It has been shown that the l 0 norm solution is closely approximated by the l 1 norm minimization
[0000] {circumflex over (x)} 1 =arg min∥ x′∥ 1 ,y=Cx′. (P1)
[0000] CS theory provides methods for minimizing the sampling rate. However, there is no guarantee that the SNR of the signals will be acceptable. When the signal is oversampled, m>2s, it is theoretically possible to improve the SNR of the decoded detector signals. However, CS theory does not provide optimal SNR solutions in the presence of noise. Therefore, in the present approach l 0 norm or l 1 norm minimization can be employed to estimate the support of the signal for constrained maximum likelihood decoding of spatially multiplexed detector readout signals. The support of a signal corresponds to the indices of the non-zero pixels (or pixels having non-negligible amplitude relative to a predetermined threshold). Thus, the CS calculation is only used to provide an estimate of the support to use as a constraint in subsequent maximum likelihood image reconstruction.
A2) ML Decoding
[0044] To decode multiplexed detector signals with optimal SNR, let the support of x, S={S i }=supp({circumflex over (x)} 0 ) or S={S i }=supp({circumflex over (x)} 1 ) for i=1Ks where s=|S| (size of set S), be found by solving (P0) using the iterative hard thresholding (IHT) algorithm or by solving (P1) using the alternating direction method (ADM). The ADM and IHT methods are both known in the art. IHT uses a non-linear modification to Landweber iterations and is computationally more efficient than ADM.
[0045] We can form a permutation matrix
[0000]
P
=
[
e
j
(
i
)
]
,
e
j
(
i
)
=
{
j
(
i
)
=
S
i
i
≤
s
j
(
i
)
=
S
i
-
s
C
s
<
i
≤
d
[0000] and apply to Eqn. (1) to yield
[0000]
y
=
[
A
B
]
[
s
n
]
+
e
[
A
B
]
=
CP
T
,
[
s
n
]
=
Px
(
2
)
[0000] where s represents the s by 1 sparse signal vector. We assume that the zero (or negligible) components of {circumflex over (x)} 1 are noise and these components are represented by the (d−s) by 1 detector noise pixel vector n. The m by s matrix A maps the signal vector s to y while the m by (d−s) matrix B maps the noise pixels to y.
[0046] The optimal SNR solution can be recovered by constructing a likelihood model with Eqn. (2). For independent identically distributed Gaussian noise pixels n, the maximum likelihood solution to (2) is given by
[0000] ŝ =( A T R −1 A ) −1 A T R −1 y
[0000] R=BE[nn T ]B T +E[ee T ] (3)
[0000] Other noise models such as Poisson distributed noise or Gaussian-Poisson mixtures could also be used in this framework with an alternate method for maximizing the likelihood function such as an iterative gradient approach.
A3) Sensing Matrices
[0047] CS theory can be used to create many different multiplexing topologies. We present two of the many possible topologies for electronic multiplexing schemes for the SiPM pixel array: 1) a standard “2-projection function” also known as “cross-strip” readout (see FIGS. 3 a - b ) and 2) a random, uniformly distributed basis sampled from the discrete cosine transform (DCT) matrix (not shown), which by CS theory, is a good candidate for a multiplexing topology. In DCT multiplexing, each channel corresponds to weighted sums of pixels with weights corresponding to the DCT coefficients.
[0048] In cross-strip multiplexing, several pixel values are summed into row and column channels. In the example of FIG. 3 a , the 16 pixels of a 4×4 imaging array are reduced to 4 row signals (solid lines) and 4 column signals (dashed lines). In the example of FIG. 3 b , the 16 pixels are reduced to 2 row signals (solid lines) and 8 column signals (dashed lines). These multiplexing concepts can be applied to larger arrays.
[0049] Sensing matrices formed by either technique can be used to recover multiple interaction events with high probability. There are degenerate cases where it is not possible to correctly resolve the positions of the multiple interactions. By carefully designing the sensing matrix and selecting the multiplexing ratio, these degenerate cases can be kept to an acceptably small percentage of the total number of events. Cross strip multiplexing is easier to implement because all of the pixels are given the same weight in any readout channel. However, the multiplexing ratio, the ratio of the number of pixels to the number of readout channels, cannot be chosen arbitrarily because the number of readout channels is equal to the number of rows plus the number of columns in the logical array. For partial DCT sensing matrices, the implementation is more difficult because the matrix is dense and continuous weights are used to form each readout channel. However, partial DCT sensing matrices enable an arbitrary multiplexing ratio. This allows greater flexibility to tradeoff readout SNR for cost/complexity.
A4) Results
[0050] We simulated a 511 keV photon randomly positioned on an 8×8 imaging array. We performed 10,000 trials of the photon producing 1, 2, and 3 interactions with equally distributed energy. Random Gaussian-distributed pixel noise was added to all 64 pixels. We compared a 16-channel, 8×8 cross strip readout against a 16-channel, partial DCT weighted 16-channel readout using l 0 norm and l 1 norm minimization and the present approach of maximum likelihood compressed sensing decoding of a set of detector pixel signals (Eqn. 3).
[0051] FIG. 4 shows the histograms of l 1 norm minimization (top) and ML−l 1 norm minimization (bottom) for 8×8 cross-strip multiplexing. The true signal value had amplitude of 30 and a variance of 1. ML−l 1 norm minimization improves the mean square error by 54% through a reduction in bias.
[0052] FIG. 5 shows the histograms for 8×8 cross-strip multiplexing using IHT (top) and ML−IHT (bottom). Both are cases of l 0 norm minimization. The true signal value had amplitude of 30 and a variance of 1. The present ML−IHT approach reduces the mean square error by up to 3%.
[0053] Table 2 summarizes the mean square error (MSE) for cross-strip multiplexing for the various signal recovery methods. ML estimation reduces the MSE for all cases. ML−l 1 is the most accurate of all approaches with a 53% reduction of MSE compared to l 1 norm minimization for single interaction events. The least amount of improvement was observed for 3-interaction events. There was a small difference between ML−IHT and IHT of no more than 3% in MSE.
[0000]
TABLE 2
Mean square error for 16-channel cross-strip multiplexing
Pixel
Signal recovery algorithm
hits
l 1
ML-l 1
IHT
ML-IHT
1
14.0 ± 0.1
6.57 ± 0.01
32.2 ± 0.2
31.2 ± 0.2
2
83.8 ± 1.4
75.1 ± 1.1
88.1 ± 1.6
88.9 ± 1.6
3
59.5 ± 0.7
54.6 ± 0.6
56.1 ± 0.6
55.5 ± 0.6
[0054] FIG. 6 shows the histograms for partial DCT multiplexing using IHT (top) and ML-IHT (bottom) with a photopeak signal of 30 and variance of 1. The bias is similar, but the variance is reduced by the ML estimation. Table 3 summarizes the MSE for partial DCT multiplexing. ML−IHT recovers signals with a 56% lower MSE for single interaction events. There was no statistically significant difference for 3-interaction events.
[0000]
TABLE 3
Mean square error for 16-channel DCT multiplexing
Pixel
NSignal recovery algorithm
hits
IHT
ML-IHT
1
11.9 ± 0.1
5.25 ± 0.01
2
36.0 ± 0.3
33.9 ± 0.2
3
44.3 ± 0.4
44.0 ± 0.4
[0055] The positioning accuracy is shown in Table 4. The percentages of events that are exactly positioned are compared for cross-strip multiplexing and partial DCT multiplexing. An accuracy of 100% indicates that all events were positioned on the correct pixel and no additional positioning blurring is introduced by multiplexing. Positioning errors lead to blurring. The results do not consider other positioning blurring that occur within the crystals, only positioning blurring caused by readout multiplexing. Partial DCT multiplexing more accurately positions the events for 1, 2, and 3 interaction cases.
[0000]
TABLE 4
Percentage of events exactly positioned on pixel
Pixel
Multiplexing method
hits
Cross-strip
Partial DCT
1
98%
100%
2
64%
87%
3
49%
60%
A5) Conclusions
[0056] We have developed a new framework for multiplexing PET detector readouts and developed a new method for optimal SNR decoding. For example, any previously developed multiplexing scheme such as Anger logic could be described in terms of a sensing matrix and the optimal ML positioning algorithm could be produced.
[0057] Compressed sensing methods can be used to recover signals for any multiplexing scheme. We demonstrate that both cross-strip and partial DCT multiplexing with l 0 and l 1 norm minimization signal recovery can resolve multiple interactions in an array of detector pixels. We also showed that l 0 and l 1 norm minimization can find the signal support for constrained ML estimation. This approach allows the underlying signal noise model to be used to improve the accuracy of signal recovery. More generally, it is expected that any other norm-constraint such as penalized l 0 and l 1 norm minimization or constrained l 0 and l 1 norm minimization (see for instance Zhang et al, User's Guide for YALL1: Your Algorithms for L1 Optimization for some examples of penalized and constrained l 1 norm minimization) that is useful for CS would also be applicable to the present ML−CS approach.
[0058] Finally, we showed that DCT multiplexing using the best signal recovery method ML−IHT yielded a 20-55% reduction in MSE for 1-3 interaction events compared to cross-strip multiplexing using ML−l 1 (the best signal recovery method for cross-strip multiplexing). This demonstrates that multiplexing by compressed sensing topologies can offer superior performance than conventional spatial multiplexing as used in standard detector readout schemes.
B) Constant Weight Codes
B1) CS Model
[0059] As described above, compressed sensing is a method to reconstruct a signal, sampled by an underdetermined linear system, using a priori knowledge that it can be sparsely represented or be compressible. In this section we consider PET block detectors that use compressed sensing to significantly reduce the number of readout (ADC) channels, while also preserving the underlying energy, spatial, and time resolution. More specifically, we have implemented a compressed sampling network that includes an array of silicon photomultiplier (SiPM) pixels that are uniquely connected to a smaller array of preamplifiers. The array of preamplifiers is then uniquely encoded into a smaller array of readout channels. This two layer multiplexing network or linear mapping network can uniquely identify the location of the event, energy, and timing. In designs that use light-sharing, all SiPM pixels in the light cone of a scintillation event are uniquely decoded. The approach presented here uses CS techniques to recover the exact magnitude of the light detected at each pixel unlike traditional linear positioning methods that simply generate the total magnitude and average position of the light produced at all pixels.
[0060] Here we consider a PET detector that is built from a large, 128 element SiPM pixel array that is either one-to-one coupled with 128 scintillation crystal elements, or in a 3:2 light-sharing design with 196 scintillation crystal elements. Light-sharing is preferable to increase the spatial resolution of the detector while not increasing the number of SiPM detector pixels.
[0061] Following the CS theory as given above, we may then describe the detector readout as:
[0000] y=C ( s+n )+ e (4)
[0000] Here y is the output vector from the multiplexing network, C is the CS matrix, s is the detector pixel output vector (which is to be estimated from y), n is the additive noise at each of the SiPM pixels, and e is the additive noise in the output channels. Using the support of the signal as described above, we can decompose Eqn. 4 into:
[0000]
y
=
[
A
B
]
[
s
n
]
+
e
(
5
)
[0000] After determining the support of the signal s and calculating the noise covariance matrix R from B,
[0000] R=BE[nn T ]B T +E[ee T ] (6)
[0000] we define a reconstruction matrix W:
[0000] W =( A T R −1 A ) −1 A T R −1 (7)
[0000] The optimal SNR solution for reconstructing the pixel value ŝ is:
[0000] ŝ=Wy (8)
[0000] Once ŝ is reconstructed, the position of ŝ is known from the support, and the spatial position can be estimated as:
[0000]
Event
position
[
x
,
y
]
=
∑
i
s
i
·
P
1
[
i
]
∑
i
s
i
(
9
)
[0000] where {right arrow over (P)}[i] is the position of pixel i, and s i are the elements of the reconstruction vector ŝ.
B2) Constant Weight Codes as Sensing Matrices
[0062] We have found that good sensing matrices for signal multiplexing are ones that have the minimum number of coefficients per column. Since each coefficient is either a connection or a discrete component, minimizing the number of non-zero coefficients reduces both the capacitive loading of the SiPM pixels and the number of discrete components. Therefore sparse codes can be used to construct good sensing matrices. We have found a large class of matrices called constant weight codes that provide just this requirement. It will be appreciated by one skilled in the art, that other sparse codes besides constant-weight codes may be used. A weight is defined as a binary connection, either zero (no connection) or one (connection). A constant 2-weight code has 2 connections per column for all columns in the matrix. In these codes, matrices are preferably optimized so that each column in the vector has the maximum Hamming distance between any pair of columns. The Hamming distance between a pair of columns is defined as the sum of the number of ones after the XOR operation between the entries of each of row entries. Maximizing the sum of the pair-wise Hamming distance makes each column as distinguishable as possible, so that they can be later uniquely reconstructed in the presence of noise.
[0063] Sensing matrices are therefore a linear map between input detector pixels and output channels. For physical implementation of the linear map, the entries can represent linear weighting of the voltage, current, or delay of the detector signal, and summing those weighted values to a subset of the outputs. If the values are binary 1's and zeros, then the linear map is implemented by connecting or not connecting the detector pixel to the specified output.
B3) Construction of Sensing Matrices
[0064] Because of significant capacitive attenuation of the signal for SiPM devices, in one example it was preferred to employ a two level CS scheme. This example has 128 detector pixels, and it is desired to multiplex these pixels to 16 output channels. Instead of a single layer 128:16 multiplexing network, a double layer multiplexing network was employed that provided 128:40 multiplexing followed by 40:16 multiplexing. The 128:40 multiplexing was provided by a first 2-constant weight code C 1 . The 40:16 multiplexing was provided by a second 2-constant weight code C 2 .
[0065] FIGS. 7 and 8 a - b show this example. FIG. 8 a shows the code matrix for code C 1 . FIG. 8 b shows the code matrix for code C 2 . FIG. 7 shows a schematic hardware implementation, where the detector pixel array 702 is multiplexed to the output channels 706 via an intermediate layer 704 . For illustrative purposes, the connections for one of the pixels of array 702 are shown (all other connections are not shown for clarity). Pixel p 10 is connected to preamplifiers a 5 and all of intermediate layer 704 . Preamplifier a 5 is connected to output channels b 3 and b 4 . Preamplifier all is connected to output channels b 7 and b 9 . Thus, pixel p 10 is connected to output channels b 3 , b 4 , b 7 , and b 9 . Every pixel in array 702 is connected to a distinct pair of preamplifiers in intermediate layer 704 . Similarly, every preamplifier in intermediate layer 704 is connected to a distinct pair of output channels. Thus, each pixel of array 702 corresponds to a unique set of 4 output channels. Since the codes are known, it is possible to invert this, such that signals in the output channels can be decoded to determine which pixel or pixels provided the outputs.
[0066] The two sensing matrices, a constant 2-weight 128:40 code ( FIG. 8 a ) and a constant 2-weight 40:16 code ( FIG. 8 b ), are specifically created to uniquely decode the maximum number of pixels firing simultaneously. Each column in the matrix has 2 connections, hence their designation as constant 2-weight codes. Equivalently, a constant weight code connects each of its inputs to the same number of outputs. Constant weight codes are used extensively for barcodes (2 of 5, 3 of 9), forward error correction codes, and many other applications in digital signal processing.
[0067] The final 4-constant weight code is derived by the multiplication of C 1 (128:40) with C 2 (40:16) to result in the final sensing matrix C(128:16). Each of the constant weight codes was calculated using a brute force heuristic search to maximize the pair wise Hamming distance between any two codes. Pixels that have been mapped to a code with a large Hamming distance can be clearly resolved from each other, even though they happen simultaneously.
[0000] B4) q-Ary Constant-Weight Codes as Sensing Matrices
[0068] Another set of codes that would also be good for a CS scheme are a class of constant-weight codes called q-ary codes. Instead of a binary 1, or 0, a q-ary code consists of 0, 1, . . . up to q unique values. A constant-weight q-ary code consists of a constant number of each value. For example, a constant [2,3,2,5] 4-ary constant-weight code, has 2 1's 3 2's, 2 3's, and 5 4's per column. Q-ary codes are also sparse, since there are only a fixed number of non-zero entries per column. For a CS scheme, the number weight of the q-ary code linear maps the q-ary value times the signal magnitude to an output channel. Therefore, the same signal model, y=C(s+n)+e, is preserved, where the compressed sensing matrix C, is a q-ary constant-weight code that linearly maps the signal s, and the noise n, to the output y.
B5) Simulation of Compressed Sensing PET Block Detector
[0069] A Matlab® script was written to Monte Carlo simulate the light-shared signal of a crystal array that was uniformly irradiated. FIG. 9 shows the model. For each scintillation crystal in a block detector 702 (either one-to-one or three-to-two coupled), a light cone 902 is generated that distributes the light onto a 2×2 subset of the 128-pixel array. Uncorrelated noise 908 is added for each SiPM pixel, and is projected through the sensing matrix 904 . Also, ADC noise 910 is directly added to the output 906 . The event is then reconstructed, and its energy and position are then calculated.
[0070] In the three-to-two light-sharing design, sub-tiled arrays of 6×6 crystals are mapped to 4×4 arrays of SiPM detectors (e.g., as shown on FIGS. 10 a - c ). Here, FIG. 10 a shows a 4×4 array of detector pixels, and FIG. 10 b shows a 6×6 array of scintillation crystals. In a light sharing design, the 6×6 array of scintillation crystals is disposed on top of the 4×4 array of pixel elements, as shown on FIG. 10 c.
[0071] The SNR for the SiPM pixel is based on the experimentally measured noise from dark counts versus the mean photo-peak signal from a 511 keV event. For illustration purposes, signal was arbitrarily set to a magnitude of 100, and variance was set to 1. Also, for each ADC, a variance of 1 was added. We compared the SNR of the recovered mean signal for a 128:16 compressed sensing design (factor of 8 reduction) versus a 128:24 cross-strip multiplexed design (5.33 factor reduction). We analyzed the ability to position all of the crystals in the CS design.
B6) SNR Analysis of Compressed Sensing Versus Cross-Strip Multiplexed PET Detector
[0072] The events were then reconstructed, the sum energy was calculated, positioned, and 2-D histogrammed. FIG. 11 a shows simulation results for one to one coupling of an 8×16 scintillation crystal array to an 8×16 detector pixel array. FIG. 11 b shows simulation results for 3:2 coupling of an 12×24 scintillation crystal array to an 8×16 detector pixel array. The scintillation crystals were resolved for both 1:1 and 3:2 designs.
[0073] For one-to-one coupled designs where a single pixel is reconstructed, we calculated a 30.6±0.1 dB SNR for CS-ML, and a 30.7±0.1 dB SNR for conventional cross-strip multiplexing. For designs where 3:2 light-sharing occurs, we calculated a 26.1±0.1 dB SNR for CS-ML, and a 28.0±0.1 dB SNR for conventional cross-strip multiplexing. The input SNR was taken to be 37 dB (from SNR=20 log 10 (511 keV peak location/σ dark counts )). FIG. 12 shows these results. The SNR improvement for the cross-strip 3:2 light-sharing design is from the lower multiplexing ratio (5.33 versus 8 ).
B7) Conclusion
[0074] We have developed a compressed sensing framework that can be used to multiplex large area SiPM-based scintillation detectors for PET. Using a two-level compression matrix, we were able to resolve a 12×24 array of scintillation crystals that were mapped to an 8×16 array of SiPM pixels using only 16 ADC readout channels.
C) Delay Encoding
[0075] In the previous examples, the CS scheme uses a linear mapping matrix C 204 that is either 0, 1 or some set of magnitudes, and this linearly maps the signal s to a set of outputs y 208 . Instead, we can describe the signal s 202 , as s(t), as a function of time. Then instead of modulating the magnitude of the signal s, we can, based on the sensing matrix C, uniquely delay the signal s(t) to an output y(t). Any method of implementing delays can be used such as physical delay elements, either as longer wires, or filters that delay the signal by a deterministic amount of time. The entries in the CS matrix C, would either, not delay (a value of zero), delay (with a time delay of 1 unit of time), or in a q-ary code, delay with a unit of q(with a time delay of q units of time). It will be appreciated by one skilled in the art, that both schemes can be advantageously combined, therefore, C=C_magnitude*C_delay, so both amplitude and time modulation can be used for imaging arrays.
[0076] A motivation to use delays is that we have an ADC converter 206 of a fixed sampling frequency F. By forming uniquely encoded time shifted copies of the signal s, and uniquely encoding these signals to a plurality of signals y, these signals y can then be digitized by a fixed frequency ADC 206 of frequency F, and a reconstructed signal {circumflex over (x)} can be of a higher sampling frequency than the Nyquist rate of the ADCs 206 sampled at a frequency F. The time interleaved sampling of signals using delays that are encoded from a binary, or q-ary constant-weight code or CS matrix, can therefore be used to synthesize a much higher effective sampling rate, and can be used to encode a multitude of detector signals into a fewer set of ADCs.
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Compressed sensing (CS) estimation approaches rely on a priori sparsity to significantly reduce the number of samples needed to provide high sampling fidelity, relative to the normal Shannon-Nyquist limit. Accordingly, CS approaches are of considerable interest for detector multiplexing in applications which have inherently sparse signals (e.g., the two correlated photon detection events in PET imaging). However, CS approaches also tend to fare poorly in the presence of noise, which has limited their applicability in practice. In this work, we show that CS estimation can be used to provide an estimate of the support of an image. This estimated support is then used as a constraint for maximum likelihood image reconstruction. This approach has robust noise performance and provides high reconstruction fidelity.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to software development tools, in particular to software conversion tools.
2. State of the Art
Software development is a time-consuming and laborious process. Maintaining and reworking previously-written software is at least equally laborious. Many times a need will arise to convert programs written to run in one software environment (i.e., written to interface to one system) to a form that will run in another different software environment. Such a conversion requires finding all language elements in the programs which refer to the old system and replacing them with language elements that refer to the new system. If the programs are large, including several hundreds of thousands or even a million or more lines of code, performing such a conversion manually is an enormous task. Clearly, it is desirable to devise a machine-assisted method of performing such a conversion.
Unfortunately, a simple "search and replace" strategy, in which every occurrence of a specified text string is replaced with a different specified text string, is too simple to provide useful results. In computer languages as in natural languages, the meaning of a particular language element is heavily context-dependent. Sometimes, for example, a local version of a name may appear. Replacing the local version of a name with a global new name results in a program that will not run or will not run correctly.
Therefore, there exists a need for a software tool that automates, to the greatest extent possible, software conversions of the type described.
SUMMARY OF THE INVENTION
The present invention, generally speaking, provides a software conversion tool that facilitates automated conversion of a software program from one operating environment to another. In accordance with one embodiment of the invention, a computer program is compiled using a compiler for a software environment other than a software environment assumed by the computer program. As a result, the compiler produces an error message. In response to the error message, source code within the computer program is automatically modified in order to remove a condition causing the error. The software conversion tool acts in concert with the compiler, which may be a standard compiler, to form in effect an error-correcting compiler, i.e., a compiler that instead of only detecting errors and presenting them to the user, is able to actually correct errors such that they do not occur during recompilation.
BRIEF DESCRIPTION OF THE DRAWING
The present invention may be further understood from the following description in conjunction with the appended drawing. In the drawing:
FIG. 1 is a perspective view of a conventional computer workstation with which the present invention may be used;
FIG. 2 is a block diagram of a portion of the computer workstation of FIG. 1;
FIG. 3 is block diagram of the error correcting compiler of the present invention; and
FIG. 4 is a flow diagram illustrating operation of the error correcting compiler of FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A computer system with which the error correcting compiler may be used will first be described, followed more particularly by a description of the error correcting compiler itself.
Referring first to FIG. 1, the error correcting compiler may be used on a computer workstation of the type shown, having a monitor 110, a keyboard 120 and a mouse 130. A mouse cursor 140 appears on the monitor screen and moves as the mouse is moved.
The internal hardware of the computer workstation of FIG. 1 may be represented in simplified block diagram form as shown in FIG. 2. The computer system has a central processor 202, a system memory 204, a display 206, a printer 208, a keyboard 210, a pointing device 212, a disk storage subsystem 214, an I/O controller 216, and interconnecting means 218 such as a system bus.
Having described the hardware environment of the invention, the software components of the error correcting compiler and their interrelation will now be more particularly described with reference to FIG. 3.
The error correcting compiler is in actuality a standard compiler operating in concert with a software conversion program. In one embodiment, the software conversion program is used to convert Objective C programs compatible with one application interface (e.g., NextStep™) to Objective C programs compatible with another application interface (e.g., OpenStep™) and is named "cvtcc", referring to the function performed by the program of converting code from one version of Objective C to another.
Referring to FIG. 3, the conversion program 310 has four principal components, a simple parser 311, a database 313, a substitution program 315 and a control program 317. The conversion program 310 operates in concert with a standard compiler 320 to convert an old program 330 that assumes an old software environment into a new program 340 that assumes a new software environment.
The parser 311 and the substitution program 315 together function as an access program. The data base 313 and the access program map old language elements into new. In particular, the parser 311 receives error messages from the compiler 320 and extracts from the error messages old resource names and the file names and line numbers where the old resource names appear. The old names are used to look up corresponding new names in the database 313. The new names, file names and line numbers are then supplied to the substitution program 315, which performs the actual substitution of the new names for the old names. The database is constructed manually by a skilled programmer familiar with both the old software environment and the new software environment.
To convert an old program to a new program, the conversion program 310 is run repeatedly by a control program 317. First, the user calls the compiler, designed or configured to compile to the new system environment instead of the old, to compile the old program. As a result, errors are generated on uses of the old system language elements. Under control of the control program, the error correcting compiler (i.e., the conversion program 310 in cooperation with the compiler 320) iteratively replaces one or more old system elements with corresponding new elements found in the conversion database and recompiles. Thus, the error correcting compiler will continue to call the actual compiler, which will fix the resulting errors until no more errors can be fixed.
Referring more particularly to FIG. 4, when the error correcting compiler begins to run, a flag fixedSome is set to false (Step 401). A regular compiler is then called to compile the program to be converted, and the error listing from the compiler is captured (Step 403). The first error message is then parsed (Step 405). If the error is not of a recognized type (Step 407), then if there is a next error message (Step 409), it is parsed, and so forth.
If the error is of a recognized type, i.e., a type that the error correcting compiler may be able to fix, such as an "identifier not found" message (Step 407), then the name of the old programmatic element is extracted from the error message (Step 411), together with the location (file, line number) of the reference to the old name. The old name is then looked up in the database (Step 413). If the old name is not found in the database (Step 415), then the next error message (if there is one) is processed. If the old name is found in the database (Step 415), then the old name is replaced with the new name found in the database (Step 417), after which the flag fixedSome is set to true (step 419).
The foregoing sequence of operation is performed for all of the error messages until there is no next error message (Step 409). Then, if fixedSome is true (Step 421), the process repeats from the beginning, by resetting fixedSome to false (Step 401) and recompiling the modified program (Step 403).
Operation proceeds in this fashion until the error correcting compiler is unable to fix any more errors, i.e., until fixedSome remains false in Step 421. The error correcting compiler then stops. Errors that the error correcting compiler was not able to fix may then be fixed manually.
The error correcting compiler may be further appreciated from the following Appendices. Appendix A is a listing of a sample database. Appendix B is a screen printout generated during use of the error correcting compiler.
Referring to Appendix A, the database, in the illustrated embodiment, is of a very simple organization. Entries beginning in the first text column are old names to be replaced. If a replacement entry is found in the database, it is entered on the line immediately following, beginning in the second text column. Not all old names have corresponding new names, and vice versa. The symbols "#", "@", "+", "-" have recognized meanings in Objective C.
Referring to Appendix B, to provide a concrete example of operation of the error correcting compiler, a version of the error correcting compiler running on a SparcStation™ computer and running under the SunOS operating system was called on the example program of lines 1-7. Beginning on line 8, the compiler is run, resulting in the four error messages listed on lines 11-14. Beginning on line 16, the conversion program is run using the error message file generated by the compiler. The conversion program first tries to fix include file errors. Hence in lines 21-24, the conversion program reports that it changed the name of the include files as specified in the database. the compiler is then called again to recompile the modified program (line 26). The errors reported in further error messages are then fixed. In line 44, the error correcting compiler reports that it has fixed all the errors it can. The resulting modified program is listed in lines 48-54. Note that "Menu" in the original program has been changed to "NSMenu", and "initTitle" has been changed to "initWithTitle".
It will be appreciated by those of ordinary skill in the art that the invention can be embodied in other specific forms without departing from the spirit or essential character thereof. The foregoing description is therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all changes which come within the meaning and range of equivalents thereof are intended to be embraced therein.
APPENDIX A__________________________________________________________________________appkit/Menu.h AppKit/NSMenu.h@interface Menu : Panel @interface NSMenu : NSPanel+ setMenuZone: (NXZone *)aZone; + (void)setMenuZone: (NSZone *)aZone;+ (NXZone *)menuZone; + (NSZone *)menuZone;#- init;initTitle: (const char *)aTitle;(id)initWithTitle: (NSString *)aTitle; // if aTitle is NULL, change it to @""(id) insertItemWithTitle: (NSString *)aString action: (SEL)aSelectorkeyEquivaient (NSStringaddItem: (const char *)aString action: (SEL)aSelector keyEquivalent:(unsigned short)charCode(id)addItemWithTitle: (NSString *)aString action: (SEL)aSelectorkeyEquivalent (NSString *)setSubmenu:aMenu forItem:aCell;(NSMenuCell *) setSubmenu: (NSMenu *) aMenu forItem: (NSMenuCell *)aCell;(NSMenu *)supermenu;(NSMenu *)attachedMenu;(BOOL) isAttached;(BOOL) isTornOff;itemList;(NSMatrix *)itemMatrix;setItemList: aMatrix;(void) setItemMatrix:(NSMatrix *)aMatrix;display;sizeToFit;(void)sizeToFit;windowMoved: (NXEvent *)theEvent;close;update;setAutoupdate: (BOOL)flag;(void) setAutoenablesItems: (BOOL) flag;(BOOL)autoenablesItems;findCellWithTag: (int)aTag;(id)cellWithTag: (int)aTag;getLocation: (NXPoint *)theLocation forSubmenu:aSubmenu;(NSPoint) locationForSubmenu: (NSMenu *) aSubmenu;mouseDown: (NXEvent *)theEvent;rightMouseDown:(NXEvent *)theEvent;#+ new;+ newTitle: (const char *)aTitle; @end@end@interface Menu (SubmenuDummyAction) @interface NSMenu (NSSubmenuDummyAction)submenuAction:sender;(void)submenuAction: (id)sender;@end @end @interface NSObject (NSMenuActionResponder)(BOOL)validateCell: (id)aCell;@end__________________________________________________________________________
APPENDIX B__________________________________________________________________________ >>:271 more ˜/all.m2 #import <appkit/appkit.h>34 void gus( ) {5 Menu *fred;6 fred initTitle: "abc"!;7 }8 >>:272 CC ˜/all.m -C -I/net/doe/export/o6p/dev8/jjh/nsrt/src/inclu de \9 -I/usr/openwin/include/X11 -I:/usr/openwin/include10 "/home/jjh/all.m", line 2: Error: Could not open include file <appkit/appkit.h>.11 "/home/jjh/all.m", line 5: Error: Menu is not defined.12 "/home/jjh/all.m", line 5: Error: fred is not defined.13 "/home/jjh/all.m", line 6: Error: fred is not defined.14 4 Error(s) detected.15 >>:273 bin/cvtCC ˜/all.m -c -I/net/doe/export/o6p/dev8/jjh/nsrt/sr c/include \16 -I/usr/openwin/include/X11 -I/usr/openwin/include17 Using default fileName: /home/jjh/myaux/src/ConversionTools/appkitdb18 *** Compiling ***19 *** Attempting to fix errors ***20 *** Fixed these msgs ***21 "/home/jjh/all.m", line 2: Error: Could not open include file <appkit/appkit.h>.22 -- from> source= `appkit/appkit.h`23 -- to> source= `AppKit/AppKit.h`24 *** Fixed some missing include file errors; recompiling ***25 *** Attempting to fix errors ***26 *** Fixed these msgs ***27 *** Fixed these msgs ***28 "/home/jjh/all.m", line 5: Error: Menu is not defined.29 -- from> file=appkit/Menu.h, source= `@interface Menu : Panel`30 -- to> file=AppKit/NSMenu.h, source= `@interface NSMenu :NSPanel`3132 *** Fixed some errors, recompiling ***33 *** Attempting to fix errors ***34 *** Fixed these msgs ***35 "/home/jjh/all.m", line 6: Warning: Cannot find instance method initTitle: \36 for class NSMenu:NSPanel:NSWindow:NSResponse:NSObject.37initTitle:(const char *)aTitle;`source= `38(id)initWithTitle:(NSString *)aTitle;`e= `39 // if aTitle is NULL, change it to @""4041 *** Fixed some errors, recompiling ***42 *** Attempting to fix errors ***4344 *** Fixed all we can in this file ***454647 >>:274 more ˜/all.m4849 #import <AppKit/AppKit.h>5051 void gus( ) {52 NSMenu *fred;53 fred initWithTitle: "abc"!;54 }__________________________________________________________________________
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A software conversion tool that facilitates automated conversion of a software program from one operating environment to another. More particularly, a computer program is compiled using a compiler for a software environment other than a software environment assumed by the computer program. As a result, the compiler produces an error message, and, in response to the error message, source code within the computer program is automatically modified in order to remove a condition causing the error. The software conversion tool acts in concert with the compiler, which may be a standard compiler, to form in effect an error-correcting compiler, i.e., a compiler that instead of only detecting errors and presenting them to the user, is able to actually correct errors such that they do not occur during recompilation.
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BACKGROUND OF THE INVENTION
[0001] The invention relates to a system having an electrically excited machine, which is controlled and is supplied with electrical energy by means of a controllable first energy store, and to a method for operating the system of the invention.
[0002] The trend is that in the future electronic systems which combine new energy store technologies with electrical drive technology will be used increasingly both in stationary applications, for instance wind power plants, and in vehicles, such as hybrid or electric vehicles. In conventional applications, as shown in FIG. 1 for example, an electric machine 101 which is in the form of a polyphase machine, for example, is controlled by means of a converter in the form of a pulse-controlled inverter 102 . A characteristic of systems of this type is a so-called DC voltage intermediate circuit 103 via which an energy store 104 , generally a traction battery, is connected to the DC voltage side of the pulse-controlled inverter 102 . In order to be able to meet the requirements placed on power and energy for a respective application, a plurality of battery cells 105 are connected in series. Since the current provided by an energy store 104 of this type must flow through all battery cells 105 and a battery cell 105 can only conduct a limited current, battery cells are often additionally connected in parallel to increase the maximum current.
[0003] The series connection of a plurality of battery cells entails the problem, in addition to a high total voltage, that the entire energy store fails when a single battery cell fails because then no battery current can flow any more. Such a failure of the energy store can lead to a failure of the entire system. In the case of a vehicle, a failure of the drive battery can cause the vehicle to “break down”. In other applications, for instance the rotor blade adjustment of wind power plants, hazardous situations may even arise in the event of unfavorable boundary conditions, for instance a strong wind. Therefore, a high degree of reliability of the energy store is always desired, where “reliability” is intended to mean the capacity of a system to operate fault-free for a predetermined time.
[0004] In the earlier applications DE 102010027857.2 and DE 102010027861.0, batteries having a plurality of battery module strings have been described which can be connected directly to an electric machine. In this case the battery module strings have a plurality of series-connected battery modules, wherein each battery module has at least one battery cell and an associated controllable coupling unit, which makes it possible, depending on control signals, to interrupt the respective battery module string or to bypass the respectively associated at least one battery cell or to connect the respectively associated at least one battery cell into the respective battery module string. By suitably actuating the coupling units, for example with the aid of pulse-width modulation, it is also possible for suitable phase signals for controlling the electric machine to be provided with the result that a separate pulse-controlled inverter is not required. The pulse-controlled inverter required for controlling the electric machine is therefore integrated in the battery, so to speak. For the purposes of the disclosure, these two earlier applications are incorporated in full in the present application.
[0005] In contrast to conventional systems, a constant DC voltage which can be used for example to supply an exciter winding of a separately excited electric machine is not available at the output of the battery system.
SUMMARY OF THE INVENTION
[0006] In accordance with one embodiment, the present invention provides a system having an n-phase separately excited electric machine, wherein n≧1, a controllable first energy store, which has n parallel energy supply branches, wherein each of the energy supply branches has a first terminal, which is connected in each case to a phase terminal of the electric machine, and a second terminal, which is connected in each case to a common reference rail, wherein the reference rail is connected to the star point of the electric machine via an exciter winding of the electric machine.
[0007] In accordance with another embodiment, the present invention provides a method for operating a system having an n-phase separately excited electric machine, wherein n≧1, and a controllable first energy store, which has n parallel energy supply branches. The method comprises the steps of providing a DC voltage component to each of the energy supply branches, feeding the DC voltage component into the phase terminals of the n-phase electric machine, and supplying an exciter winding of the electric machine with the DC voltage component fed into the phase terminals in order to generate an excitation field in the electric machine.
[0008] One concept of the present invention is to supply an exciter winding of a separately excited electric machine via the star point of the electric machine. As a result of this, the exciter winding can be interconnected with the star point inside the electric machine, and so an external motor connection in the system of the invention is no longer required. Here, all of the components necessary for the operation of the electric machine are already present in the energy storage module and so no further components are necessary for supplying the exciter winding.
[0009] A further concept of the present invention is to change the potential in the star point of an electric machine by means of a simple actuation of energy storage modules in the energy supply branches, in order to be able to vary the current through the exciter winding of the electric machine and therefore to change the excitation of the machine. The method of actuation can easily be integrated into existing actuation concepts for actuating the stator windings of the electric machine.
[0010] According to an advantageous embodiment, a system can have at least two series-connected energy storage modules in each of the n parallel energy supply branches, which energy storage modules comprise in each case at least one electrical energy storage cell having an associated controllable coupling unit. In this case, the coupling units can be configured in full-bridge circuit connection or in half-bridge circuit connection, depending on whether or not a reversal of the current direction in the energy supply branches is desired. Some of the series-connected energy storage modules can be controlled via the coupling units in such a way that a direct current component is applied to the output supply voltage in each of the energy supply branches. Said direct current component can then be fed into the exciter winding via the phase terminals and the star point of the electric machine. As a result, the potential in the star point can be varied in steps. By means of appropriate clocking of at least one energy storage module, the potential at the star point can also be steplessly adjusted.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Further features and advantages of embodiments of the invention arise from the following description.
[0012] FIG. 1 shows a schematic illustration of a system having an electric machine from the prior art,
[0013] FIG. 2 shows a schematic illustration of a system having an electric machine and a controllable energy store,
[0014] FIG. 3 shows a schematic illustration of a system having an electric machine and a controllable energy store according to an embodiment of the present invention, and
[0015] FIG. 4 shows a schematic illustration of a system having an electric machine and a controllable energy store according to another embodiment of the present invention.
DETAILED DESCRIPTION
[0016] FIG. 2 shows a system having an electric machine 1 and a controllable energy store 2 . The electric machine 1 is illustrated as a three-phase electric machine 1 by way of example, which is supplied with energy via a controllable first energy store 2 . The controllable first energy store 2 comprises three energy supply branches 2 a , 2 b , 2 c , which are connected on one side to a reference potential 9 (reference rail), which, in the illustrated embodiments, carries a medium potential with respect to the phases U, V and W of the electric machine 1 , via terminals 4 a , 4 b , 4 c and on the other side in each case to the individual phases U, V, W of the electric machine 1 . In this case, a terminal 3 a of a first energy supply branch 2 a is coupled to a first phase terminal 1 a of the electric machine 1 , a terminal 3 b of a second energy supply branch 2 b is coupled to a second phase terminal 1 b of the electric machine 1 and a terminal 3 c of a third energy supply branch 2 c is coupled to a third phase terminal 1 c of the electric machine 1 . Each of the energy supply branches 2 a , 2 b , 2 c has series-connected energy storage modules 5 a , 6 a or 5 b , 6 b or 5 c , 6 c . By way of example, the number of energy storage modules per energy supply branch 2 a , 2 b , 2 c in FIG. 2 is two, wherein any other number of energy storage modules is also possible, however.
[0017] The energy storage modules 5 a , 5 b , 5 c , 6 a , 6 b , 6 c in turn comprise in each case a plurality of series-connected electrical energy storage cells in an energy storage cell unit 7 . In this case, the number of energy storage cells in an energy storage cell unit 7 in FIG. 2 is two, for example, wherein any other number of energy storage cells is also possible, however. The energy storage modules 5 a , 5 b , 5 c , 6 a , 6 b , 6 c also comprise in each case a coupling unit 8 which is associated with the energy storage cells 7 of the respective energy storage module 5 a , 5 b , 5 c , 6 a , 6 b , 6 c . For reasons of clarity, the coupling units and the energy storage cell units are only provided with reference signs in the energy storage module 5 c . However, it is clear that the energy storage modules 5 a , 5 b , 6 a , 6 b , 6 c can comprise similar coupling units and energy storage cell units.
[0018] In the illustrated variant embodiments, the coupling units 8 are in each case formed by four controllable switching elements, which are interconnected in the form of a full bridge. The switching elements can be configured as power semiconductor switches here, for example in the form of IGBTs (insulated gate bipolar transistors) or as MOSFETs (metal oxide semiconductor field-effect transistors). However, it is also possible to form the coupling units 8 in each case as half-bridge circuits with only two switching elements in each case. Half-bridge circuits afford the advantage of having lower power losses owing to the lower number of switching elements, however they have the disadvantage that the polarity of the voltage at the output terminals 3 a , 3 c of the energy supply branches cannot be reversed.
[0019] In the case, illustrated by way of example, of a full-bridge circuit, the coupling units 8 make it possible to interrupt the respective energy supply branch 2 a , 2 b , 2 c by opening all of the switching elements of a coupling unit 8 . Alternatively, the energy storage cells 7 can be either bypassed or switched into the respective energy supply branch 2 a , 2 b , 2 c by closing in each case two of the switching elements of a coupling unit 8 .
[0020] The total output voltages of the energy supply branches 2 a , 2 b , 2 c are determined by the respective switching state of the controllable switching elements of the coupling units 8 and can be adjusted in steps. The stepwise adjustment results depending on the voltage of the individual energy storage modules 5 a , 5 b , 5 c , 6 a , 6 b , 6 c.
[0021] The coupling units 8 therefore make it possible to connect the phases U, V and W of the electric machine 1 either relative to a high reference potential or relative to a low reference potential and to this extent can also perform the function of a known inverter. Thus, the power and mode of operation of the electric machine 1 can be controlled by the controllable first energy store 2 given suitable actuation of the coupling units 8 . The controllable first energy store 2 therefore performs a dual function to this extent since it is used firstly for electrical energy supply and secondly also for controlling the electric machine 1 .
[0022] The electric machine 1 has stator windings which are mutually interconnected in a star connection in a known manner. The electric machine 1 is embodied as a three-phase AC machine in the illustrated exemplary embodiments; however, it can also have fewer or more than three phases. The number of energy supply branches 2 a , 2 b , 2 c in the controllable first energy store 2 accordingly depends on the number of phases of the electrical machine.
[0023] FIG. 3 shows a schematic illustration of a system having an electric machine 1 and a controllable energy store 2 according to one embodiment of the present invention. The system illustrated in FIG. 3 differs from the system illustrated in FIG. 2 merely in that an exciter winding 11 is connected at a star point 10 of the electric machine 1 , said exciter winding in turn being connected in each case to the terminals 4 a , 4 b , 4 c of the controllable energy store 2 via the reference rail 9 .
[0024] In the event of conventional actuation of the controllable first energy store 2 , a medium potential is present at the star point 10 . However, said potential can be shifted by in each case the energy storage cells 7 of one or more energy storage modules 5 a , 5 b , 5 c , 6 a , 6 b , 6 c of each energy supply branch 2 a , 2 b , 2 c being switched with positive or negative polarity into the respective energy supply branch 2 a , 2 b , 2 c by means of appropriate actuation of the associated coupling units 8 with continuous or clocked operation. The voltages at the energy supply branches 2 a , 2 b , 2 c are thus increased or decreased in each case to a value which is above or below a voltage value which is required at that time for supplying energy to the electric machine 1 .
[0025] By means of said increase or decrease of the voltages at the energy supply branches 2 a , 2 b , 2 c , a DC voltage component can be fed into the star point 10 via the phase terminals 1 a , 1 b , 1 c and so the potential at the star point 10 can be changed. A variable current can be conducted through the exciter winding 11 via the feedback coupling of the star point 10 with the reference rail 9 of the controllable energy store 2 and so a variable excitation field can be generated in the electric machine 1 . By means of this interconnection, which can occur inside the electric machine, a separate motor connection for supplying the exciter winding 11 is no longer necessary.
[0026] In the present exemplary embodiment according to FIG. 3 , a reversal of polarity of the current through the exciter winding 11 can be achieved with the full-bridge circuit of the coupling units 8 by means of an appropriate actuation of the energy storage modules 5 a , 5 b , 5 c , 6 a , 6 b , 6 c . However, it is also possible, for example, to implement each of the energy storage modules 5 a , 5 b , 5 c , 6 a , 6 b , 6 c with coupling units 8 in a half-bridge circuit. If said energy storage modules are used to provide the DC voltage component to the phase terminals 1 a , 1 b , 1 c , it is then no longer possible to effect a reversal of polarity of the current through the exciter winding, however the power losses at the switching elements of said energy storage modules are reduced owing to the lower number of required switching elements in a half-bridge circuit of the coupling units 8 .
[0027] FIG. 4 shows a schematic illustration of a system having an electric machine and a controllable energy store according to another embodiment of the present invention. The system according to FIG. 4 differs from the system according to FIG. 3 substantially in that each of the energy supply branches 2 a , 2 b , 2 c only has one energy storage module. Furthermore, coupling units and energy storage cells 7 are provided in the energy storage modules of the energy supply branches 2 a , 2 b , 2 c , which coupling units and energy storage cells are associated with the respective energy storage modules. By way of example, the energy storage module 5 a with coupling units 8 a and 8 b and an energy storage cell unit 7 is illustrated in the energy supply branch 2 a . In FIG. 4 , the energy storage cell unit 7 can be connected and/or bypassed by means of a half-bridge circuit with the terminals 3 a and/or 4 a . For this purpose, a coupling unit 8 a is located in a branch in parallel with the energy storage cell unit 7 and a coupling unit 8 b is connected in series in the branch of the energy storage cell unit 7 . As is also illustrated in FIG. 4 , it is possible in principle for each of the energy storage modules to be configured with different coupling units, for example with coupling units in half-bridge circuit connection and coupling units in full-bridge circuit connection. However, it is obviously also possible to configure all energy storage modules in FIG. 4 with coupling units in half-bridge circuit connection.
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The invention relates to a system comprising an n-phase separately excited electrical machine ( 1 ), with n≧1, a controllable first energy store ( 2 ) which has n parallel energy supply branches ( 2 a, 2 b, 2 c ), every energy supply branch ( 2 a, 2 b, 2 c ) comprising a first connection ( 3 a, 3 b, 3 c ) that is connected to a respective phase connection ( 1 a, 1 b, 1 c ) of the electrical machine ( 1 ), and a second connection ( 4 a, 4 b, 4 c ) that is connected to a common reference bus ( 9 ), said reference bus ( 9 ) being connected to the neutral point ( 10 ) of the electrical machine ( 1 ) via a field winding ( 11 ) of the electrical machine (1).
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This invention relates to a multi-conductor cable grounding connection and a method of manufacture therefor.
BACKGROUND OF THE INVENTION
Demand for high density packaging has led to the development of multi-wire cable having signal conductors, grounding conductors, and shielding arranged on very close centers. To do this, it has been necessary to utilize extremely fine and frequently fragile elements. For example, signal and conductor or drain wires may have diameters on the order of 0.003 to 0.009 inches. Shielding ground is typically provided by a wraparound conductive film on the order of 0.001 inch or fine braid with numbers of cables having such elements and characteristics combined together in ribbon form. These cables are made to have specific impedances relative to the types of signals required to be transmitted, and care must be taken to keep ground and signal spacings appropriate to avoid discontinuities with particular care taken in stripping such cable of the outer insulating and protective sheath, engaging the different conductors and mechanically and electrically interconnecting such conductors to signal, ground, and shielding circuits of either a connector or a circuit board or the like. Thin foil grounding and shielding conductors have proven to be most difficult to reliably terminate, by solder or mechanical means providing an electrical interconnection thereto. In certain instances, a fine drain or separate wire is used, being engaged along the length of the foil conductor to make such interconnection. As a result, termination of multi-wire cable, and particularly multi-wire coaxial cable, has proven to be time consuming, difficult, anticostly with numerous defects requiring expensive cable assemblies to be scrapped.
U.S. Pat. No. 4,929,195 granted May 29, 1990 and directed to a shielded connector, teaches the use of an electrically conductive body called a stopper that is applied to the shielding of a multi-wire cable. The stopper includes an outer groove and serves to mechanically and electrically connect the shielding of the cable to an outer shielding of a connector. This serves to protect against tensile forces applied to the cable and shield wire and further, to interconnect the shield wire to the outer metallic portions of the connector without the use of solder. U.S. Pat. No. 4,614,398 granted Sep. 30, 1986 is directed to a shielded cable terminal connection wherein a resilient bushing of conductive material is inserted between the shield portions of a coaxial cable and the inner surface of a backshell housing that is crimped down against the resilient bushing to provide a mechanical and electrical connection to coaxial cable and a connector. U.S. Pat. No. 3,744,128 granted Jul. 10, 1973 teaches the use of making shielded connector assemblies utilizing an electrically conductive potting material to provide a conductive path between cable shield and the metallic housing of a connector. Also of background is U.S. Pat. No. 4,828,512 granted May 9, 1989 and drawn to a connector for flat electrical cable employing an elastomeric material that is conductive to enclose the connection for EMI/EMP shielding. Of these prior art teachings, only U.S. Pat. No. '512 appears to deal with small or very fine conductors, and such teaching is confined to a particular shielded flat flex cable employing a low durometer elastomeric material and small conductive balls to effect an interconnection of cables.
Accordingly, it is an object of the present invention to provide an electrical connection of multi-wire cables and method that facilitates a common electrical grounding and mechanical holding of the fragile parts of such cable. It is still a further object to provide an electrical connection and method of manufacture facilitating the interconnection of fine foil, ground and shielding conductors of multi-wire cable. It is a further object to provide an improved electrical connection and method of manufacture of a common grounding element having features facilitating mounting and retention of cables relative to a further connector or circuit. It is a final object of the invention to provide a novel housing construction in conjunction with a casting or molding of plastic material into such housing around the shielding of fine multi-wire cable.
SUMMARY OF THE INVENTION
The present invention achieves the foregoing objectives through the provision of a connection and method that strips away the ends of a multi-wire cable, such as a coaxial cable, to expose the grounding and shielding foil that surrounds a dielectric medium and a signal conductor, followed by a casting of conductive elastomeric material over the segments of stripped foil to effect a common ground of the foil without solder or other mechanical connection thereto. In one embodiment, the body thus formed is made to include a regular box-like volumetric shape that can be utilized to fit within a connector to facilitate termination of the signal conductors of the cables and of the common shielding conductors. In another embodiment, the body of conductive plastic material is made to include surfaces that allow the application of fasteners to the body directly to form, in essence, a housing. The surfaces may include ears having apertures therein to allow the application of fasteners or latches allowing the body to be snapped into a fixture or a connector. In one embodiment, a commoning bus is included in the process to be molded into the body and is made to include contact fingers that extend from the body to engage shielding or grounding circuits on a connector or a printed circuit board or the like. In a still further embodiment, a thin wall, plastic housing adapted to snap together around the stripped ends of a multi-wire coaxial cable or the like is made to include an aperture or apertures allowing the interior volume to be filled with conductive elastomeric material to form the body, the plastic housing either being later removed or left in place permanently to insulate against unwanted and accidental contact with other circuits. The housing may include a bus bar in the base thereof with contact fingers extending out of the housing for interconnection to the conductive body therein and the foil grounding shields of a multi-wire cable. The invention contemplates a number of materials that are essentially of a plastic and insulating material loaded with conductive particles, fibers, platelets, to render the body sufficiently conductive to achieve good, low-resistance, and stable interconnection with the foil of a cable to extend a ground path to a circuit with which the cable is used. The invention contemplates that the loading of the plastic material with conductive elements be controlled to assure that the body will have an appropriate mechanical strength for holding the cables together in position relative to a connector or connection and in certain instances, allowing the forming of surfaces, fasteners, latches or the like out of the body material. The invention also contemplates the use of conductive gels contained within the version including the thin wall housing, such gels readily providing adequate interconnection with low force engagement with the foil. An important aspect of the invention is the provision of a "broad area of contact" between the relatively large areas of exposed foil and that of the body as contrasted with the "asperity" interconnection, typical of most electrical connections with conductors.
IN THE DRAWINGS
FIG. 1 is a perspective of the end of a multi-wire cable showing the different elements as stripped preparatory to application of the method of the invention.
FIG. 2 is a view of the cable of FIG. 1 having an encapsulation of conductive material over the ground and shielding braid of the cable.
FIG. 3 is a view of the cable of FIG. 1 with a body molded over the braid of the cable and including a bus bar in such body.
FIG. 4 is a side, partially sectional view showing a cable terminated to a connector and printed circuit board employing the body shown in FIG. 2.
FIG. 5 is a perspective of an alternative configuration of the conductive body of the invention.
FIG. 6 is a perspective of a further embodiment of the body of the invention.
FIG. 7 is a perspective of an alternative embodiment of the invention including a plastic housing utilized to cast or mold the body of the invention.
FIG. 8 is a front, elevational view of an alternative housing including fastener means in an alternative embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, a multi-wire cable 10 is shown including a plurality of individual multi-wire cables 12 that are in a coaxial form in the illustration. Each of the cables 12 includes an outer sheath or jacket 14 made of an insulating material to hold the cable elements together and protect the cable integrity dimensionally as well as against moisture and the like. Each cable 12 further includes a grounding shield 16, typically formed of a conductive braid of fine wires as shown; or of foil, aluminum foil and copper foil formed of very thin coatings of such material on backing film such as mylar or the like. Within shield 16 is a dielectric medium in the form of a sleeve 18, typically extruded or otherwise formed over a center signal conductor 20. The conductor 20 is typically formed of solid or stranded copper wire that may be plated with either non-precious or precious metals, depending on the technique of termination employed. Cables such as 10 come in a variety of sizes with individual cables 12 numbering from two or three up to forty or more, the cables frequently being bound together by adhesive or by coextrusion of the outer jacket 14 and, in certain cases, a weaving or the use of a backing sheet or film to which they are bonded. Cables such as 10 come in a variety of geometries, including the coaxial geometry shown and in certain cases, other geometries where signal and ground conductors are held spaced apart by a suitable dielectric medium to give a controlled impedance to the cable, 50, 70, and 90 ohm impedance cables being widely employed. In certain instances, again depending upon the type of termination employed, a further wire, sometimes termed a drain wire or a ground wire, is applied along the length of the cable in connection with the grounding shield 16 adjacent the conductive side of such if it is foil on a film. Frequently, this drain wire is or may be located at any point around the periphery of the foil due to the high speed and low cost extrusion process employed. In other instances, the drain wire position is held to be in the same location, right or left and side of the cable, to facilitate mass termination through IDC techniques employed for both the signal wire and the drain wires. In most cases, these wires, signal and/or drain, braid or conductive foil are extremely fragile and difficult to handle without breakage or damage. Needless to say, damage or breakage of the wire or foil of even a single cable 12 can result in a failure of function of the devices served by the cable. When dealing with a multi-wire cable of 20, 30 or 40 individual cables, the difficulty in carefully unwrapping the shield 16 of each cable and of positioning such shielding to be terminated in some fashion can be readily appreciated.
Referring now to FIG. 2, the cable 10, including the individual cables 12 as shown stripped in FIG. 1, are encapsulated by the application of a body 22 over the stripped segments of shields 16. The body 22 is simultaneously formed as by molding or casting a conductive plastic material around the stripped segments of the shields 16 of cables 12. This is accomplished simultaneously and commonly by the use of a mold form that has an interior shape that can be derived from FIG. 2 and an exterior shape defined by the configuration of the cable and the body as shown in FIG. 2. The terms molding and casting are used to refer to this step of the method. In regards to molding or casting, care must be taken with respect to the flow of material and the use of pressure that could deform the shield 16 inwardly crushing the dielectric medium 18 or at least displacing it to alter the dielectric constant effective in that segment and thus create a discontinuity of coaxial transmission path that can result in signal reflections and energy lost as well as signal distortion.
A variety of materials may be employed with respect to forming body 22, such materials being in essence a plastic polymer or silicon-type rubber loaded with conductive particles in the form of spheres such as small glass beads plated over with conductive material, conductive platelets, conductive fibers, and conductive particles. In general, the higher the loading of conductive particles into the plastic matrix, the higher the conductivity and lower resistivity of the path created between the shields 16 and the outside of body 22. This loading, while reducing resistivity, also reduces mechanical strength, and care must be taken in use of the body to make sure that there is both sufficient conductivity and sufficient mechanical strength for different applications and adaptations using the invention. A range of plastic materials, including urethane, acrylics, epoxies and rubbers, may be employed. The use of conductive epoxy forms a body having excellent conductivity and excellent mechanical strength whereas use of some of the other materials may lack mechanical strength on the one hand or conductivity on the other depending upon the load of conductive particles.
As an important point, the use of the invention technique assumes a broad even contact between the shield 16, braid, foil or drain wire and the material of the body 22, an area far greater than the usual contact area of crimped, soldered or IDC terminations afford. This better assures a good connection to fine conductors.
FIG. 3 shows an embodiment of the invention similar to that shown in FIG. 2 but including a metal bus bar 26 having contact fingers 28 extending therefrom to facilitate an electrical interconnection of body 22 to grounding paths or shielding circuits associated with the cable. It is contemplated that the bus bar 26 may be inserted into the mold utilized to form body 22 and become part of the body 22. The invention contemplates that the bar 26 may be formed of a thin, relatively soft copper material for use in applications where the fingers 28 will be soldered to a circuit. Alternatively, the bar 26 may be formed of a thin spring grade material, such as brass or phosphor bronze so that the fingers 28 have spring characteristics to engage a grounding or shielding surface of a connector or board resiliently and provide a ready disconnect of the bus bar circuit and cable assembly.
FIG. 4 shows, in cross-section, an application of an assembly of cables 12, the elements of the cable being numbered as before. As can be seen, the cable, as prepared, including body 22, fingers 28, and the signal conductors 20, is positioned within a connector housing 36 that includes a plastic block, that surrounds the outer diameter of cable 12 and extends around block 22. An outer shield 40 is shown, including a portion 41 that fits against the sheath 14 to provide mechanical support. Flanges, as at 42, allow an interconnection of the connector 36 to a chassis or facade associated with equipment served by the cable. In FIG. 4, an interconnection between the cable 12 and a printed circuit board 30 is shown, the signal conductor 20 being connected by solder as at 33 to a signal circuit 32 on the surface of board 30. The bus bar 26, through protruding fingers 28, is shown terminated as by solder or pressure to a circuit 34 forming the ground circuit of the printed circuit board; it being understood that the circuits 32 and 34 are interconnected to traces leading to components mounted on board 30, such circuits being either on surfaces of the board or embedded within the board as is standard practice.
As can be appreciated from FIG. 4, strains applied to cable 12 will be received and resisted by portions of the connector 36 through which the cable passes, but also by the engagement with body 22 fitted within 38. The use of a regular shape, volumetric shape and configuration for body 22 enables a use with connectors having predefined cavities or recesses like that show in FIG. 4. This contrasts with a filling of a material into a cavity following assembly.
FIG. 5 shows an alternative body 22' that is made to include ears or projections 50 apertured as at 52 to allow the body to be used directly as a connector and applied to either a further connector or to a printed circuit board or the like. To be noted in FIG. 5 are the fingers 28 protruding from the bulk of the material. With respect to body 22', care must be taken in terms of the choice of the material and the loading of conductive particles to maintain a mechanical strength to allow projections 50 to be employed to lock the cable assembly to a board or the like. FIG. 6 shows a further alternative in the form of a body 22'' having ears 54 that have a limited bendability to provide a latching function so that the cable assembly may be plugged into a further connector, not shown, or a mechanical receptacle mounted on a printed circuit board or the like or otherwise employed in interconnecting to further circuits. The conductive characteristics of the body 22 serve to common the grounding shields of numerous cables. With respect to the embodiment of FIG. 6, again a selection must be made of the characteristics of the material employed and the fill of conductive particles to allow use of flexible latch ears such as 54.
FIG. 7 shows a still further embodiment of the invention in the form of a housing 60, typically made of a light insulating plastic, such as polypropylene or polyethylene or the like. The housing 60 includes a shell 62 having an injection port 64, at least one. On the ends of the shell 62 are latches 66, made flexible and rounded surfaces 68 that f it tightly against the shield 16 of a cable passed therethrough. Housing 60 also includes a shell 70 that has walls 72 apertured as at 74 and including recesses 76 aligned and dimensioned to receive the latches 66. Note that a bus bar 26 is contained within shell 72 with the fingers 28 protruding from the side in this particular embodiment. In FIG. 8, a housing similar to 60 shown as 60' includes shells 62' and 70' and additionally includes fasteners 80 integrally formed with shell 70'. The fasteners 80 at each end include legs 82 separated by a slot 84 and have surfaces to allow the fasteners to be deformed inwardly upon insertion into a hole in a piece of equipment, a grounding shield of a connector, or a printed circuit board.
In practice, a cable assembly 10 is stripped as indicated in FIG. 1, with the housing 60 or 60' applied thereover, snapped together to define an interior volume having the desired configuration of block 22. With the housings in position, suitable conducting material may be injected through a port like 64, the interior venting around the surfaces 68, or if necessary, additional vents being utilized. Depending upon the choice of plastic, the heat and pressure utilized, the housings 60 and 60' may allow either a direct molding from an injection head, care again being taken to limit pressure to avoid crushing of the cable within the housing or, alternatively, a material may be poured in through the port 64 and allowed to f ill the volume and harden over a period of time. Use of these housings can be thus employed to avoid tieing up molding machines in cable end fabrication. Additionally, the use of the housings allow a wider range of plastic material that cannot practically or effectively be used with respect to high speed molding operations, epoxy being one example of such materials.
The housings 60 and 60' insulate essentially the blocks 22 from accidentally touching some circuit and causing problems with the use with assembly, it being necessary in such case to provide an interconnection to the blocks with the bus bar 26 being molded within the housing and including the projecting fingers 28 allowing the block 22 to be interconnected to a grounding and shielding circuits.
It should be now apparent that the invention contemplates an electrical grounding connection that may be used by itself, a connection like that shown in FIG. 2, and as well, a connection that includes a body having surfaces or features as in FIGS. 5 and 6 to assist in fastening or attaching not only the block but the cable and assembly to some equipment or connector served by the cable assembly. The invention also contemplates the use of a separate plastic housing to help form the body of the invention and the methods associated with these different embodiments. The invention contemplates that different features may be employed with respect to these teachings.
Having now described the invention relative to the drawings, claims are attached that are deemed to define the invention.
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A grounding connection and method for use with multi-wire cable (10) of a type having a plurality of individual cables (12) arranged in side-by-side relationship with each cable including an outer insulation sheath (14) extending around a relatively fragile, thin ground shield (16) in turn extended around a dielectric sleeve (18) carrying a fine signal wire (20) includes the provision of a body (22) of conductive plastic molded or cast around the exposed shield to provide a permanent electrical interconnection and commoning of the shield (16) of the multiple cables. A grounding bus (26) is used with the body (22) to interconnect ground circuits to external ground paths of circuit boards or the like. An alternative embodiment includes plastic material having sufficient strength to form fasteners (50) or latches (54) extending the use of the body (22). A thin wall plastic housing (60) may be used as an alternative definition of a cavity into which the material is poured to form the body (22).
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. application Ser. No. 13/848,993, filed on Mar. 22, 2013, which claims priority from U.S. Provisional Application No. 61/614,673, filed Mar. 23, 2012, both of which are incorporated by reference herein in their entirety.
FIELD OF THE INVENTION
[0002] This invention generally relates to lath, and more particularly to an integrated drainage system with lath for use in stone, or thin brick, veneer and stucco.
BACKGROUND
[0003] The use of hard coat stucco has been employed as a building material since literally ancient days. For stucco and plaster applications, a lath or mesh is typically applied to the surface of the wall or ceiling structure. This provides mechanical holding or keying for the unhardened stucco or plaster. Metal lath is often used as the reinforcement when stucco or plaster is applied over open frame construction, sheathed frame construction, or a solid base having a surface that might otherwise provide an unsatisfactory bond for the stucco or plaster. When applied over frame construction, one may employ base coats of plaster with a total thickness of approximately ⅜ inch to approximately ¾ inch to produce a solid base for a decorative finish coat. Metal lath reinforcement is also recommended for the application of stucco and plaster to old concrete or masonry walls, especially if the surface is lacking in compatibility with the base layer. There are also plastic laths available for the same purpose as metal lath.
[0004] According to the International Conference of Building Officials Acceptance Criteria for Cementitious Exterior Wall Coatings, AC 11, effective Oct. 1, 2002, and evaluation report NER-676, issued Jul. 1, 2003, wire fabric lath should be a minimum of No. 20 gauge, 1 inch (25.4 mm) (spacing) galvanized steel woven-wire fabric. The lath should be self-furred, or furred when applied over all substrates except unbacked polystyrene board. Metal lath has structural integrity, but if made of steel can corrode over time. The metal can also unfavorably react with the chemistry of the plaster or stucco. Hence, plastic or non-metal lath has gained popularity.
[0005] Stone veneer has also gained in popularity. Mounting of stone veneer using lath can present similar issues to that of plaster and stucco. A concern with the stone veneer, and even stucco, is that moisture can find its way behind the outer stone or stucco surface. This can present itself by way of hole penetrations in putting up the lath, and water condensing or otherwise migrating behind the lath.
SUMMARY
[0006] In one aspect of the invention, a matrix of randomly oriented plastic or other durable fibers which are relatively rigid, or which can be treated to be relatively rigid or organized into a matrix that is relatively rigid, is employed as the lath. An example of the foregoing kind of material is sold under the name MORTAR NET, sold by Mortar Net, Inc. of Burns Harbor, Ind., and such as disclosed in U.S. Pat. No. Re. 36,676. Such a matrix lath would preferably be on the order of around except ¼″ thick (in front to back width). The matrix lath would preferably be provided in large sheets or rolls having substantial length and height.
[0007] In this embodiment, preferably affixed to the matrix lath, as by bonding thereto, is a layer that will form a water channel layer and spacer inboard to the matrix lath. In one form, this water channel layer is of a material similar to that of the foregoing matrix lath, but of a smaller fibrous diameter entangled randomly oriented plastic or other durable fiber, formed in a thinner width, such as 3/16″ or ¼″ WALLNET product, which is made and sold under that name by Mortar Net, Inc. from stock material made by the Fiber Bond Corporation. WALLNET is an airlaid, nonwoven media composed of polyester fibers bonded with a blend of PVC polymers and an anti-microbial, with a general weight of about 3.5 oz/yd2. This water channel layer is of similar length and height as that of the matrix lath. While this water channel layer is preferably joined to the matrix lath in some manner, it could be separate in use.
[0008] Additionally, although not necessarily, a further layer of material may be provided in the form of a thin scrim that would be between the matrix lath and the water channel face outward from the structure. The scrim layer is much more tightly structured, preferably non-woven, but is water permeable. It is of like length and height as the matrix lath and water channel layer. The scrim adds some further integrity to the construct, it acts as an insect barrier, and provides additional protection against mortar clogging the water channel layer.
[0009] In use, the foregoing embodiment of matrix lath and water channel layer, including scrim if desired, is affixed to an inner wall structure, as by nailing or screwing thereto, with the water channel layer most inboard and against the wall structure. Plaster can be applied to the matrix lath in a standard manner of application. The water layer forms a drainage plane that allows water which may have penetrated cracks in the stucco or between the mortar and veneer, to drain out; such water incursion is normal in brick construction that creates the need for a cavity wall construction. Effectively, the water channel layer functions as a cavity filled with mesh. Water is effectively blocked from entering the structure, however, and drains vertically downward through the mesh of the water channel layer, to exit the wall at the bottom, as being drained through weep holes or the like. The water exit at the bottom might be accomplished by having a layer at the bottom of the wall with drainage channels similar to that shown in U.S. Pat. Nos. 7,543,413 and 7,543,414.
[0010] In an alternative embodiment, a thin sheet of plastic thermoformed to have features to capture mortar, not unlike metal lath, may be provided for the water channel layer. This could be an open-weave type material that is formed with corrugations or projections extending from what would be the plane of the material.
[0011] In a further embodiment, the lath is spaced from the water layer (with or without scrim layer), through the use of spacers, such as soft foamacious elements. The spacers themselves may also act as receptacles for the screws or nails used to put up the lath. In this way, the foam material serves to “seal” the penetrations made in the wall structure. The spacers can also be arranged in a manner to catch debris falling behind the lath, while still allowing water to pass. The spacers could be arranged as blocks spaced laterally from one another, of any desired shape (rectangle, circle, etc.).
[0012] In another embodiment, a combination of spacers and scrim is contemplated. In this version, a non-woven scrim material is provided with integral thermoplastic bumps affixed thereto over a surface. The bumps may be a rubber or other somewhat flexible material, for instance, which can serve not only a stand-off function, but also receive a nail or other fixation device through the bump, thus yielding a self-sealing function.
[0013] Additionally, a water or vapor barrier can further be provided as the innermost (inboard) layer of the construct.
[0014] In an embodiment, the foregoing combination of flexible fibrous or matrix lath, spacers, water channel layer, with or without scrim and/or vapor barrier, can be made unified, and provided as a more or less continuous roll stock material. An installer thus would only need to “cut to size” for the application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1A is a perspective view of a wall structure with a lath and water channeling construct made in accordance with the invention;
[0016] FIG. 1B is another perspective view of a wall structure with a lath and water channeling construct made in accordance with the invention;
[0017] FIG. 2 is a sectional view taken along line 2 - 2 of FIG. 1B ;
[0018] FIG. 3 is a view of a corrugated lath material; and
[0019] FIG. 4 is a perspective view of a scrim material with stand-off elements.
DETAILED DESCRIPTION
[0020] Referring now to FIGS. 1B and 2 in particular, a construct in the form of a structural support for plaster, stucco and stone veneer is disclosed. A typical wall is shown, being formed of studs 10 to which a wallboard or wood sheathing 12 is attached in well-known manner.
[0021] Outboard of the wallboard 12 (inboard being toward the studs 10 ), is a water channel material 14 . In this embodiment, the water channel material is a fibrous mesh or matrix made up of thin plastic filaments or fibers. Such a material is sold by Mortar Net, Inc. under the name WALLNET. Here, the material is about inch to about 2 inch thick in width (width being measured normal to the substantially planer front side 15 and backside 16 of the water channel material 14 ). The water channel material thus generally fills the width defined between front side 15 and backside 16 , forming a circuitous pathway for water that may then flow therebetween. The water channel material nonetheless can catch and hold debris that might fall thereon from above, without clogging the water channel thereby provided.
[0022] If desired, a vapor barrier layer (not shown) may be provided inboard of the water channel material, against the wallboard. This could be a plastic sheet, or a spray-on vapor barrier.
[0023] Next outboard from the water channel material 14 is an optional scrim 18 . Scrim 18 is a non-woven sheet material in this embodiment which permits air and water to pass therethrough, but can provide some additional support and serve as a barrier to tiny insects.
[0024] A lath material 20 is provided. There are many known types of lath, including metal and plastic being most commonly used. The lath serves as the main supporting structure for receiving and holding plaster or stucco, or some cementitious or other adhesive compound for holding stone veneer 22 , for instance.
[0025] In this embodiment, spacers 23 are used between the lath 20 and the scrim/water channel material. The spacers 23 may advantageously be glued or otherwise adhered to one or both of the layers on either side thereof. Spacers 23 are made of a soft foam material, which provides a self-sealing barrier for water when nails, screws or the like are driven through the spacers, so as to mount the lath 20 to the wallboard 12 .
[0026] It will be understood that some of the foregoing elements need not be employed in the exact order shown in FIGS. 1B and 2 . The elements may be employed, for example, in the order shown in FIG. 1A .
[0027] Note that one of the advantages of the present invention is that the construct of water channel material 14 , spacers 23 and lath 20 , with or without scrim 18 , with or without vapor barrier, can be provided as a unitary whole. Especially advantageous is to make the construct as a roll stock material, so that a builder may simply unroll the amount desired and “cut to size,” more or less.
[0028] FIG. 3 shows a type of material 25 that could be used as a lath material in this application. Here, it is a filamentous plastic having thin diameter elements 26 that run roughly parallel to one another, which are joined by other elements 27 that cross therebetween. The elements 26 , 27 having sufficient rigidity to be formed into a somewhat corrugated surface having peaks and valleys. The material is open, so as to receive plaster, stucco, or other cementitious or adhesive material therein, and thereby serve the function of lath.
[0029] FIG. 4 shows a variation on the scrim 18 , which is here provided with integral stand-off elements or bosses. Scrim 18 ′ is as previously described, being a high loft non-woven thin material. This could also be some other material, whether non-woven or not. Attached to scrim 18 ′ are the bosses or bumps 24 , which are affixed to one side of the scrim, as by bonding thereto. These bosses 24 may be made of a material that can readily receive a nail, screw or the like, and thereby attach the scrim in a manner whereby the fastener is self-sealed by the boss through which it passes. A rubber or rubber-like material may be used, or some softer thermoplastic, just to name two examples. The combination of scrim plus stand-off elements may have good advantage in field application.
[0030] Thus, while the present invention has been described with respect to a certain embodiment, numerous changes and modifications will be apparent to those of skill in the art, and such changes and modifications are intended to be encompassed within the spirit of the invention, as defined by the claims.
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An improved lath is disclosed having a water drainage layer provided in association with the lath. The water drainage layer serves to remove water that might otherwise build up between the lath and wall structure.
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CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of application Ser. No. 09/875,063 filed Jun. 6, 2001, pending.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to a method and apparatus for dicing or sawing semiconductor substrates having encapsulated semiconductor devices thereon and more specifically to a saw and chuck and method of using the same employing using multiple indexing techniques and multiple blades for more efficient sawing from an array of semiconductor devices on a substrate.
[0004] 2. State of the Art
[0005] An individual integrated circuit semiconductor device, semiconductor die, or chip is usually formed from a larger structure known as a semiconductor wafer, which is usually comprised primarily of silicon, although other materials such as gallium arsenide and indium phosphide are also sometimes used. Each semiconductor wafer has a plurality of integrated circuits arranged in rows and columns with the periphery of each integrated circuit being rectangular. Typically the wafer is sawn or “diced” into rectangularly shaped discrete integrated circuits along two mutually perpendicular sets of parallel lines or streets lying between each of the rows and columns thereof. Hence, the separated or singulated integrated circuits are commonly referred to as dice.
[0006] One exemplary wafer saw includes a rotating dicing blade mounted to an aluminum hub and attached to a rotating spindle, the spindle being connected to a motor. Cutting action of the blade may be effected by diamond particles bonded thereto, or a traditional “toothed” type blade may be employed. Many rotating wafer saw blade structures are known in the art. The present invention is applicable to any saw blade construction so further structures will not be described herein.
[0007] Because semiconductor wafers in the art usually contain a plurality of substantially identical integrated circuits arranged in rows and columns, two sets of mutually parallel streets extending perpendicular to each other over substantially the entire surface of the wafer are formed between each discrete integrated circuit and are sized to allow passage of a wafer saw blade between adjacent integrated circuits without affecting any of their internal circuitry. Prior to the sawing of a semiconductor wafer to singulate the wafer and to create individual semiconductor die from the wafer, a piece of tape, typically referred to as wafer tape, is applied to the back side of the wafer so that once the wafer has been singulated, the individual semiconductor die remain attached to the wafer tape for further handling and processing.
[0008] Once the wafer tape has been applied to the back side of the wafer, a typical wafer sawing operation includes attaching the semiconductor wafer to a wafer saw carrier, mechanically, adhesively or otherwise as known in the art and mounting the wafer saw carrier on the table of the wafer saw. A blade of the wafer saw is passed through the surface of the semiconductor wafer, either by moving the blade relative to the wafer, the table of the saw and the wafer relative to a stationary blade, or a combination of both. To dice the wafer, the blade cuts precisely along each street, returning back over (but not in contact with) the wafer while the wafer is laterally indexed to the next cutting location. Once all cuts associated with mutually parallel streets having one orientation are complete, either the blade is rotated 90° relative to the wafer or the wafer is rotated 90°, and cuts are made through streets in a direction perpendicular to the initial direction of cut. Since each integrated circuit on a conventional wafer has the same size and rectangular configuration, each pass of the wafer saw blade is incrementally indexed one unit (a unit being equal to the distance from one street to the next) in a particular orientation of the wafer. As such, the wafer saw and the software controlling it are designed to provide uniform and precise indexing in fixed increments across the surface of a wafer.
[0009] Once the individual or singulated semiconductor die have been sawed, the semiconductor die are further processed by being removed from the wafer tape, attached to substrates and packaged, such as the semiconductor die being adhesively attached to a substrate in a board-over-chip configuration (BOC), connections made between the semiconductor die and the circuits of the substrate by wire bonding, and the semiconductor die and portions of the substrate being encapsulated. While the semiconductor die and substrate may be individually handled, it is more efficient to process a plurality of semiconductor die, each semiconductor die being individually mounted, on a substrate having a configuration providing for each individually mounted semiconductor die thereon and circuits for connection with each individually semiconductor die as well as for the encapsulation of each individual semiconductor die mounted on the substrate.
[0010] However, existing process equipment and apparatus do not have the capability of singulating the packaged semiconductor die on a substrate when a plurality of semiconductor die are contained in an array on a substrate.
BRIEF SUMMARY OF THE INVENTION
[0011] Accordingly, an apparatus and method for sawing semiconductor substrates, including substrates having a plurality of semiconductor devices of different sizes and/or shapes therein, is provided. In particular, the present invention provides a saw and method of using the same capable of “multiple indexing” of a saw blade or blades to provide the desired cutting capabilities. As used herein, the term “multiple indexing” contemplates and encompasses both the lateral indexing of a saw blade at multiples of a fixed interval and at varying intervals which may not comprise exact multiples of one another. Thus, for conventional substrate and/or wafer configurations containing a number of equally sized integrated circuits, the wafer saw and method herein can substantially simultaneously saw the substrates and/or wafers with multiple blades and therefore cut more quickly than single blade wafer saws known in the art. Moreover, for wafers having a plurality of differently sized or shaped integrated circuits, the apparatus and method herein provides a multiple indexing capability to cut nonuniform dice from the same wafer.
[0012] The present invention includes a substrate chuck mounted on a table used in conjunction with the saw for holding a substrate having an array of encapsulated semiconductor devices mounted thereon for singulation. The chuck comprises a chuck table, at least one cutting pedestal, at least one clamp, at least one clamp pedestal, and an alignment apparatus for aligning a substrate for singulation in the chuck. The alignment apparatus may comprise at least one alignment pin having a portion thereof attached to the chuck table and having a portion engaging the substrate to be singulated or a recess in the chuck table for receiving the substrate to be singulated therein.
[0013] In one embodiment, a single-blade, multi-indexing saw is provided for cutting a substrate containing variously configured semiconductor devices thereon which may be encapsulated. By providing multiple-indexing capabilities, the saw can sever the wafer into differently sized mounted encapsulated semiconductor devices corresponding to the configuration of the semiconductor devices contained thereon.
[0014] In another embodiment, a saw is provided having at least two wafer saw blades spaced a lateral distance from one another and having their centers of rotation in substantial parallel mutual alignment. The blades are preferably spaced apart a distance equal to the distance between adjacent areas for cutting the substrate. With such a saw configuration, multiple parallel cuts through the substrate can be made substantially simultaneous, thus essentially increasing the speed of cutting a substrate by the number of blades utilized in tandem. Because of the small size of the individual semiconductor devices mounted and/or encapsulated on the substrate and the correspondingly small distances between adjacent cutting areas on the substrate, it may be desirable to space the blades of the saw more than one cutting area apart. For example, if the blades of a two-blade saw are spaced two cutting areas apart, a first cut would cut the first and third laterally separated cutting areas. A second pass of the blades through the substrate would cut through the second and fourth streets. The blades would then be indexed to cut through the fifth and seventh streets, then sixth and eighth, and so on.
[0015] In yet another embodiment, at least one blade of a multi-blade saw is independently raisable relative to the other blade or blades when only a single cut is desired on a particular pass of the carriage. Such a saw configuration has special utility where the blades are spaced close enough to cut in parallel on either side of larger encapsulated semiconductor devices, but use single blade capability for dicing any smaller integrated circuits. For example, a first pass of the blades of a two-blade saw could cut a first set of adjacent cutting areas of the substrate defining a column of larger semiconductor devices on the substrate. One blade could then be independently raised or elevated to effect a subsequent pass of the remaining blade cutting along a cutting area of the substrate that may be too laterally close to an adjacent street to allow both blades to cut simultaneously, or that merely defines a single column of narrower semiconductor devices. This feature would also permit parallel scribing of the surface of the substrate to mutually isolate conductors from, for example, tie bars or other common links required during fabrication, with subsequent passage by a single blade indexed to track between the scribe lines to completely sever or singulate the adjacent portions of the substrate.
[0016] In still another embodiment, at least one blade of a multi-blade saw is independently laterally translatable relative to the other blade or blades. Thus, in a two-blade saw, for example, the blades could be laterally adjusted between consecutive saw passes of the sawing operation to accommodate different widths between cutting areas of the substrate. It should be noted that this embodiment could be combined with other embodiments herein to provide a wafer saw that has blades that are both laterally translatable and independently raisable, or one translatable and one raisable, as desired.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] FIG. 1 is a schematic side view of a first preferred embodiment of a wafer saw in accordance with the present invention;
[0018] FIG. 2 is a schematic front view of the wafer saw illustrated in FIG. 1 ;
[0019] FIG. 3 is a schematic front view of a second embodiment of a wafer saw in accordance with the present invention;
[0020] FIG. 4 is a schematic front view of a third embodiment of a wafer saw in accordance with the present;
[0021] FIG. 5 is a top view of an array of semiconductor devices on a substrate;
[0022] FIG. 6 is a bottom view of the array of semiconductor devices on a substrate illustrated in drawing FIG. 5 ;
[0023] FIG. 7 is a top view of a substrate chuck according to the present invention for the sawing of the array of semiconductor devices on a substrate illustrated in drawing FIG. 5 and drawing FIG. 6 ;
[0024] FIG. 8 is a side view taken along line 8 - 8 of drawing FIG. 7 of the substrate chuck according to the present invention;
[0025] FIG. 9 is a schematic view of a silicon semiconductor wafer having variously sized semiconductor devices therein to be diced with the saw;
[0026] FIG. 10 is a schematic view of another silicon semiconductor wafer having variously sized semiconductor devices therein to be diced with the saw;
[0027] FIG. 11 is a top view of a portion of a semiconductor substrate bearing conductive traces connected by tie bars;
[0028] FIG. 12 is a top view of a portion of a semiconductor substrate bearing three different types of components formed thereon;
[0029] FIG. 13 is a top view of an alternative substrate chuck according to the present invention for the sawing of the array of semiconductor devices on a substrate illustrated in drawing FIG. 5 and drawing FIG. 6 ; and
[0030] FIG. 14 is a side view taken along line 8 - 8 of drawing FIG. 13 of the substrate chuck according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] As illustrated in drawing FIGS. 1 and 2 , an exemplary wafer saw 10 to be used with the present invention is comprised of a base 12 to which extension arms 14 and 15 suspended by support 16 are attached. A substrate saw blade 18 is attached to a spindle or hub 20 which is rotatably attached to the extension arm 15 . The blade 18 may be secured to the hub 20 and extension arm 15 by a threaded nut 21 or other means of attachment known in the art. The substrate saw 10 also includes a translatable substrate table 22 movably attached in both X and Y directions (as indicated by arrows in drawing FIGS. 1 and 2 ) to the base 12 . The table 22 used to hold the chuck 500 , 500 ′ (see drawing FIGS. 7, 8 , 13 , and 14 ) of the present invention thereon by any suitable attachment apparatus. Alternatively, blade 18 may be translatable relative to the table 22 to achieve the same relative X-Y movement of the blade 18 to the table 22 . A substrate 24 to be scribed or sawed at 24 ′ may be securely mounted to the table 22 . As used herein, the term “saw” includes scribing of a substrate, the resulting scribe line not completely extending through the substrate. Further, the term “substrate” includes any suitable type substrate to which a semiconductor device may be attached, such as FR-4 board, silicon substrate, traditional full semiconductor wafers of silicon, gallium arsenide, or indium phosphide and other semiconductor materials, partial wafers, and other equivalent structures known in the art wherein a semiconductor material table or substrate is present. For example, so-called silicon-on-insulator or “SOI” structures, wherein silicon is carried on a glass, ceramic or sapphire (“SOS”) base, or other such structures as known in the art, are encompassed by the term “substrate” as used herein. Likewise, “semiconductor substrate” may be used to identify wafers and other structures to be singulated into smaller elements.
[0032] The saw 10 is capable of lateral multi-indexing of the table 22 having a chuck 500 or blade 18 or, in other words, translatable from side-to-side in drawing FIG. 2 and into and out of the plane of the page in drawing FIG. 1 , various nonuniform distances. As noted before, such nonuniform distances may be mere multiples of a unit distance, or may comprise unrelated varying distances, as desired. Accordingly, a substrate 24 having variously sized integrated circuits or other devices or components therein may be sectioned or diced into its non-uniformly sized components by the multi-indexing saw 10 . In addition, as previously alluded, the saw 10 may be used to create scribe lines or cuts that do not extend through the substrate 24 . The substrate 24 can then subsequently be diced by other methods known in the art or sawed completely through after the blade 18 has been lowered to traverse the substrate to its full depth or thickness.
[0033] Before proceeding further, it will be understood and appreciated that design and fabrication of a substrate saw for use with the present invention having the previously referenced, multi-indexing capabilities, independent lateral blade translation and independent blade raising or elevation is within the ability of one of ordinary skill in the art, and that likewise, the control of such a device to effect the multiple-indexing (whether in units of fixed increments or otherwise), lateral blade translation and blade elevation may be effected by suitable programming of the software-controlled operating system, as known in the art. Accordingly, no further description of hardware components or of a control system to effectuate operation of the apparatus of the invention is necessary.
[0034] Referring now to drawing FIG. 3 , another illustrated embodiment of a substrate saw 30 is shown having two laterally spaced blades 32 and 34 with their centers of rotation “C” in substantial parallel alignment transverse to the planes of the blades. For a rectangular substrate or a conventional substantially circular silicon semiconductor wafer each having a plurality of similarly configured semiconductor devices 42 (not shown) or integrated circuits 42 (not shown) arranged in evenly spaced rows and columns, the blades can be spaced a distance “D” substantially equal to the distance between adjacent areas 44 or streets 44 (not shown) defining the space between each integrated circuit 42 . In addition, if the areas 44 of a substrate 40 or streets 44 of wafer 40 are too closely spaced for side-by-side blades 32 and 34 to cut along adjacent streets, the blades 32 and 34 can be spaced a distance “D” substantially equal to the distance between two or more areas 44 or streets 44 . For example, a first pass of the blades 32 and 34 could cut along streets 44 a and 44 c and a second pass along streets 44 b and 44 d. The blades could then be indexed to cut the next series of areas or streets and the process repeated as desired number of times. If, however, the semiconductor devices 42 of a substrate 40 or integrated circuits 42 of a wafer 52 have various sizes, such as integrated circuits 50 and 51 as illustrated in drawing FIG. 9 , at least one blade 34 is laterally translatable relative to the other blade 32 to cut along the areas or streets 44 , such as street 56 , separating the variously sized integrated circuits 50 . The blade 34 may be variously translatable by a stepper motor 36 having a lead screw 38 or by other devices known in the art, such as high precision gearing in combination with an electric motor or hydraulics, or other suitable mechanical drive and control assemblies. For a substrate 40 or wafer 52 , the integrated circuits, such as integrated circuits 50 and 51 , may be diced by setting the blades 32 and 34 to simultaneously cut along areas 58 or 59 (see drawing FIG. 6 ) streets 56 and 57 , indexing the blades, setting them to a wider lateral spread and cutting along areas 56 or 57 or areas 58 and 59 , indexing the blades while monitoring the same lateral spread or separation and cutting along streets 60 and 61 , and then narrowing the blade spacing and indexing the blades and cutting along other areas (not shown) and streets 62 and 63 . The substrate 40 or wafer 52 could then be rotated 90° and the blade separation and indexing process repeated for areas 58 or 59 or vice versa (see drawing FIG. 6 ) and streets 64 and 65 , streets 66 and 67 , and streets 68 and 69 .
[0035] As illustrated in drawing FIG. 4 , a wafer saw 70 according to the present invention is shown having two blades 72 and 74 , one of which is independently raisable (as indicated by an arrow) relative to the other. As used herein, the term “raisable” includes vertical translation either up or down. Such a configuration may be beneficial for situations where the distance between adjacent cutting areas of a substrate and/or streets of a wafer is less than the minimum lateral achievable distance between blades 72 and 74 , or only a single column of narrow semiconductor devices or semiconductor dice is to be cut, such as at the edge of a substrate or wafer. Thus, when cutting a wafer 80 , as better illustrated in drawing FIG. 10 depicting a wafer, the two blades 72 and 74 can make a first pass along streets 82 and 83 . One blade 72 can then be raised, the wafer 80 indexed relative to the unraised blade 74 and a second pass performed along street 84 only. Blade 72 can then be lowered and the wafer 80 indexed for cutting along streets 85 and 86 . The process can be repeated for streets 87 (single-blade pass), 88 , and 89 (double-blade pass). The elevation mechanism 76 for blade 72 may comprise a stepper motor, a precision-geared hydraulic or electric mechanism, a pivotable arm which is electrically, hydraulically or pneumatically powered, or other means well-known in the art.
[0036] Finally, it may be desirable to combine the lateral translation feature of the embodiment of the substrate saw 30 illustrated in drawing FIG. 3 with the independent blade raising feature of the wafer saw 70 of drawing FIG. 6 . Such a wafer saw could use a single blade to cut along areas or streets that are too closely spaced for dual-blade cutting or in other suitable situations, and use both blades to cut along variously spaced areas or streets where the lateral distance between adjacent cutting areas or streets is sufficient for both blades to be engaged.
[0037] It will be appreciated by those skilled in the art that the embodiments herein described while illustrating certain embodiments are not intended to so limit the invention or the scope of the appended claims. More specifically, this invention, while being described with reference to substrates for semiconductor devices thereon, either encapsulated or not, semiconductor wafers containing integrated circuits or other semiconductor devices, has equal utility to any type of substrate to be scribed or singulated. For example, fabrication of test inserts or chip carriers formed from a silicon (or other semiconductor substrate) or wafer and used to make temporary or permanent chip-to-wafer, chip-to-chip, and chip-to-carrier interconnections and that are cut into individual or groups of inserts, as described in U.S. Pat. Nos. 5,326,428 and 4,937,653, may benefit from the multi-indexing method and apparatus described herein.
[0038] For example, illustrated in drawing FIG. 11 , a semiconductor substrate 100 may have traces 102 formed thereon by electrodeposition techniques required connection of a plurality of traces 102 through a tie bar 104 . A two-blade saw in accordance with the present invention may be employed to simultaneously scribe substrate 100 along parallel lines 106 and 108 flanking a street 110 in order to sever tie bars 104 of adjacent substrate segments 112 from their associated traces 102 . Following such severance, the two columns of adjacent substrate segments 112 (corresponding to what would be termed “dice” if integrated circuits were formed thereon) are completely severed along street 110 after the two-blade saw is indexed for alignment of one blade therewith, and the other blade raised out of contact with substrate 100 . Subsequently, when either the saw or the substrate carrier is rotated 90°, singulation of the segments 112 is completed along mutually parallel streets 114 . Thus, substrate segments 112 for test or packaging purposes may be fabricated more efficiently in the same manner as dice and in the sizes and shapes.
[0039] As shown in drawing FIG. 12 , a portion of a substrate 200 is depicted with three adjacent columns of varying-width segments, the three widths of segments illustrating batteries 202 , chips 204 and antennas 206 of a semiconductor device, such as an RFID device. With all of the RFID components formed on a single substrate 200 , an RFID module may be assembled by a single pick-and-place apparatus at a single work station. Thus, complete modules may be assembled without transfer of partially assembled modules from one station to the next to add components. Of course, this approach may be employed to any module assembly wherein all of the components are capable of being fabricated on a single semiconductor substrate. Fabrication of different components by semiconductor device fabrication techniques known in the art is within the ability of those of ordinary skill in the art, and therefore no detailed explanation of the fabrication process leading to the presence of different components on a common wafer or other substrate is necessary. Masking of semiconductor device elements not involved in a particular process step is widely practiced, and so similar isolation of entire components is also easily effected to protect the elements of a component until the next process step with which it is involved.
[0040] Further, the saw used with the present invention has particular applicability to the fabrication of custom or nonstandard integrated circuits or other components, wherein a capability for rapid and easy die size and shape adjustment on a substrate-by-substrate or wafer-by-wafer basis is highly beneficial and cost-effective. In the present saw it may be desirable to have at least one blade of the independently laterally translatable blade configuration be independently raisable relative to the other blade or blades, or a single blade may be both translatable and raisable relative to one or more other blades and to the target substrate or wafer. In addition, while for purposes of simplicity, some of the preferred embodiments of the substrate saw are illustrated as having two blades, however, the saw may have more or less than two blades.
[0041] Referring to drawing FIG. 5 , a first side 300 of a substrate 40 is illustrated having a plurality of semiconductor devices 42 located thereon. Each semiconductor device 42 having been previously encapsulated in a suitable molding process. The substrate 40 may be of any suitable material, such as described herein.
[0042] Referring to drawing FIG. 6 , another side 302 of the substrate 40 is illustrated having the plurality of semiconductor devices 42 connected to a plurality of solder balls or suitable type connectors 306 through suitable circuits (not shown) on substrate 40 and from the encapsulated semiconductor devices 42 . The substrate 40 may contain circuits thereon, such as illustrated in drawing FIG. 11 .
[0043] Referring to drawing FIG. 7 , illustrated in a top view is a dicing chuck 500 suitable for use with the table 22 of the substrate saw 10 and the substrate 40 illustrated in drawing FIGS. 5 and 6 . The chuck 500 comprises a chuck table 502 having a shaft 528 ( FIG. 8 ) attached thereto for mounting on the table 22 using suitable apparatus, a plurality of cutting pedestals 504 having the desired spacing to mate with the semiconductor devices 42 of substrate 40 and connectors 306 of another side 302 of substrate 40 , a pair of clamps 506 mounted on clamp pedestals 508 (see drawing FIG. 8 ), and one or more alignment pins 510 , if desired, for aligning the substrate 40 on the chuck 500 . Each cutting pedestal 504 includes a portion 512 having an aperture 514 therein for mating with the portion of the semiconductor device 42 on another side 302 thereof and portions 516 having a plurality of recessed areas 518 therein for mating with the connectors 306 in areas 308 (see drawing FIG. 6 ) of another side 302 of substrate 40 . The aperture 514 in the cutting pedestal 504 may be connected to a source of vacuum (not shown) to help retain the semiconductor devices 42 on the cutting pedestal 504 . The shape, size and spacing of the recessed areas 518 on each cutting pedestal 504 will vary with the type, size, and spacing of the connectors 306 of another side 302 of substrate 40 . The clamps 506 mounted on clamp pedestals 508 may be secured thereto by any suitable type of retaining apparatus, such as a threaded member 520 . The chuck 500 may be fabricated from any suitable material, such as metal commonly used for the dicing of substrates having semiconductor devices thereon.
[0044] Referring to drawing FIG. 8 , the chuck 500 illustrated in a side view. As shown, the apertures 514 in each cutting pedestal 504 has an aperture 522 connected to aperture 524 which, in turn, is connected to aperture 526 in the chuck shaft 528 to supply vacuum from a source of vacuum to each cutting pedestal 504 . The shape, size, configuration, and layout of the apertures 522 ; 524 , and 526 may be any suitable desired configuration to supply vacuum to each cutting pedestal 504 . The alignment pins 510 mate with alignment apertures 43 in the substrate 40 (see drawing FIGS. 5 and 6 ). The alignment pins 510 may be any desired configuration, size, and shape to mate with any alignment aperture in substrate 40 . The threaded member 520 may be any suitable type to retain the substrate clamps 506 on the clamp pedestals 508 . The substrate clamps 506 may be of any suitable shape, size, and configuration to mate with portions of the substrate 40 to retain portions thereof on the cutting pedestals 504 and, if desired, on clamp pedestal 508 .
[0045] Each of the cutting pedestals 504 is spaced from an adjacent cutting pedestal 504 by a space 503 and space 505 which also extends both between the cutting pedestals 504 and one the exterior of the cutting pedestals 504 to allow a saw blade 18 of a saw as described herein to cut a substrate 40 into the desired number of singulated semiconductor devices 42 , each singulated semiconductor device 42 having a plurality of connectors 306 attached to one side thereof. In this manner, an array of any desired number of semiconductor devices 42 on a substrate 40 may be retained in the chuck 500 to be singulated by a saw 10 having one or more blades 18 . Additionally, since the depth and width of a saw 10 may vary, any spacing of the semiconductor devices 42 on the substrate 40 may be used.
[0046] Referring to drawing FIGS. 13 and 14 , an alternative chuck 500 ′ according to the present invention is illustrated. In the alternative chuck 500 ′ of the present invention, the alignment pins 510 have been eliminated. The chuck table 502 includes a recess 510 ′ therein having the size, configuration, and shape to mate and align a substrate 40 within the recess 510 ′ prior to being retained therein by the clamps 506 on clamp pedestals 508 . In this manner, a substrate 40 may be located by the perimeter of the recess 510 ′ on the cutting pedestals 504 being retained thereon by a vacuum supplied through aperture 514 and clamps 506 . Except for the elimination of the alignment pins 510 and the addition of an alignment recess 510 ′ in the table 502 of the chuck 500 ′, the chuck 500 ′ is the same as the chuck 500 illustrated in drawing FIG. 7 and drawing FIG. 8 .
[0047] The chuck 500 and 500 ′ of the present invention may include alterations and features, changes, additions, and deletions which are intended to be within the scope of the invention. For instance, the chuck may be of any size, shape, and configuration. The chuck may have any desired number of cutting pedestals of any size, shape, and configuration thereon, may have any desired number, shape, size, and configuration of clamps and clamp pedestals, may have any desired alignment apparatus for a substrate thereon, etc.
[0048] Thus, while certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the invention disclosed herein may be made without departing from the scope of the invention, which is defined in the appended claims.
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A semiconductor wafer saw and method of using the same for dicing semiconductor wafers are disclosed comprising a wafer saw including variable lateral indexing capabilities and multiple blades. The wafer saw, because of its variable indexing capabilities, can dice wafers having a plurality of differently sized semiconductor devices thereon into their respective discrete components. In addition, the wafer saw with its multiple blades, some of which may be independently laterally or vertically movable relative to other blades, can more efficiently dice silicon wafers into individual semiconductor devices.
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This is a division of Ser. No. 07/404,166, filed Sept. 7, 1989, now U.S. Pat. No. 5,059,205.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to implantable blood filters and more particularly to vena cava filters which resist migration once they have been emplaced in a vessel.
2. Prior Art
Blood clots (emboli) carried in the blood stream often constitute serious threats to health and in some instances, to life itself. The reduction of such clots, or their stabilization and arrest of further migration in the circulatory system of the body, are desiderata constantly motivating the development by the medical profession of new techniques and devices for this purpose. Although emboli moving in other portions of the circulatory system can also present serious problems, development of means for preventing emboli from migrating into the pulmonary circulation from the vena cava has received the primary attention.
Ligation of the vena cava was an early technique to minimize movement of emboli therein, with collateral circulation being relied upon to provide adequate venous return of blood to the heart. This procedure, which involved major abdominal surgery, progressed to the utilization of harpstring filters; staple plication; smooth, serrated and channeling external clips evolving into intravascular springs; balloons; and filters. The utilization of filters emplaced in the vascular system provides the obvious advantage over ligation of major blood vessels such as the vena cava, of not requiring general anaesthesia surgery and laparotomy.
U.S. Pat. No. 3,540,431 discloses an intravascular filter for entrapment and arresting of emboli, advanced by Mobin-Uddin and associates. The Mobin-Uddin filter is an umbrella type structure which includes a plurality of expanding struts or ribs which carry points at the divergent ends thereof which impale or engage the vessel wall when the filter is in its expanded state. This device has had problems with migration, and it was withdrawn from the market in 1986.
U.S. Pat. No. 3,952,747 to Kimmell, Jr., incorporated, herein by reference, discloses a vena cava filter as well as a method and apparatus for percutaneous insertion of that filter into a human. The Kimmel disclosure defines the filter as having a plurality of convergent legs disposed in a generally conical array and joined at their convergent ends to an apical hub, each leg having a reversely bent hook at is distal end.
An advancement of the Kimmel, Jr. reference is shown in U.S. Pat. NO. 4,817,600 to Herms et al, also incorporated herein by reference, which discloses a titanium filter having a plurality of legs joined to a head or nose bead, the legs having a first straight portion, and sharply divergent legs extending therefrom.
BRIEF SUMMARY OF THE INVENTION
The present invention features a filter of the Kimmell type having significant improvements to further minimize the likelihood of filter migration and to permit the filter to be emplaced through a small hole and into a vessel. In a first aspect of the invention, the filter of the type mentioned has a head, a plurality of legs attached to the head and divergent leg portions, each leg having securement means on its distal end with respect to the head, the improvement being that the securement means on the distal end of each leg being of multiple curvilinear configuration to define a pad which permits hook engagement of a vessel wall in which the filter is emplaced, while preventing penetration of that hook through the vessel wall, which might otherwise damage body tissue.
In a second or further aspect of the invention, the filter, which in this embodiment preferably is made from stainless steel, has a head with a plurality of legs extending distally therefrom, the head and legs having a centrally disposed longitude axis. The legs have proximal portions which are secured to the head, the proximal portions being generally parallel to the longitudinal axis to the filter. The legs have first portions closely distally adjacent to the head, which have a curvature therein, which geometry allows resilient deformation of the filter into the carrier, and subsequent resilient deformation when expelled from the carrier, so that the filter can end up as a general conical configuration of the legs with respect to the head of the filter. The legs also have a second portion distal to the first portion having a larger radius of curvature so as to permit a slight radial flaring of the hook ends of the legs when the filter is ejected out of its carrier, reducing the possibility of the hooks from becoming entangled with one another, while allowing the legs to be compressed radially inwardly, permitting the filter assembly to be placed into a smaller diameter carrier without stressing the stainless steel material of the legs beyond their elastic limit which would result in the filter having a smaller base diameter upon release from the carrier.
Another aspect of this invention involves the head having a central bore which is arranged co-axially with the longitudinal axis of the filter assembly. The central bore in the head is adapted to receive a guidewire during and after release of the filter assembly from its carrier as an aid for the alignment and centering of the filter assembly within a blood vessel during its implantation.
The first aspect of this invention more particularly involves the arrangement of the distalmost end of each leg defining a pad or landing, and spaced proximally therefrom, there is arranged a hook pointing outwardly from its respective leg in a manner generally normal thereto, and extending further radially outwardly from the longitudinal axis of the filter, than does the pad or landing thereadjacent, to permit the hook to engage the wall of the vessel, yet prevent deep penetration of the wall of the vessel by the hook and leg portions. Each pad or landing on the distalmost end of each leg is comprised of a reverse twisted segment of the wire of the leg, or a segment of the leg welded to the distalmost end and parallel thereto, the segment itself having the hook thereon, extending outwardly radially beyond the radially outwardmost portion of the pad or landing.
The second aspect of this invention more particularly involves the plurality of radially directed curves of each of the legs wherein the first radius of curvature for each leg begins closely distally adjacent the head of the filter, and defines an arc of about 0.5 inches in length with a radius of curvature of about 1.4 inches. The second radius of curvature for each leg extends across an arc about 1 inch in length along the distalmost portion of each leg, with a radius of curvature of about 8.4 inches, each leg being about 2.1 inches in total length. The first radius of curvature provides the generally conical aspect of the legs and head, while allowing delivery of the filter assembly through small holes and distributing the strain throughout the arc of the curve of the leg which is generated when the legs are collapsed into the small opening of the carrier, thus eliminating strains in excess of the yield strain, and the second radius of curvature being sufficient to keep the hooks from entangling with one another when the filter is ejected out its carrier device or during loading thereof, as shown in the aforementioned patent incorporated herewithin.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects and advantages of the present invention will become more apparent when viewed in conjunction with the following drawings, in which:
FIG. 1 is a perspective view of a vena cava filter showing the head and legs thereof in one embodiment of this invention;
FIG. 2 is a side elevational view of the distal end of the preferred embodiment of one of the legs of a vena cava filter engaged with the cava wall;
FIG. 3 is a side elevational view of the distal end of a leg of a prior art filter and the cava wall;
FIG. 4 is a side elevational view of a further embodiment of the distal end of a leg of a vena cava filter;
FIG. 5 is a view taken along the lines V--V of FIG. 4;
FIG. 6 is a perspective view of a vena cava filter showing the head and legs thereof of a further embodiment of this invention;
FIG. 7 is a radially inwardly directed view upon one leg and the head of a vena cava filter; and
FIG. 8 is a view taken along the lines VIII--VIII of FIG. 7, showing a further embodiment of the legs of a filter constructed according to the principles of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings in detail, and particularly to FIG. 1, there is shown a first embodiment of a vena cava filter 10 having an apical hub or head 14 of generally cylindrical shape.
The filter 10 includes a plurality of elongated legs 16 which are of equal length, and are preferably identically configured to each other. The legs 16 are collectively arranged in a generally conical geometric configuration so that the legs 16 converge in the apical head 14, and are symmetrically spaced about a central longitudinally disposed axis "L", which is shown extending through the head 14, in FIG. 1. The legs are of equivalent diameter, being about 0.018 inches in diameter fabricated from stainless steel or titanium wire, and are of about 2.02 inches in final length. In the embodiment of the present invention, six legs are provided, however only one will be described in detail.
At its outermost end 18 which is distal with respect to the apical head 14, each leg 16 has a main portion 20 and a reversely bent portion 22 which is bent through an angle of about 180° in the plane which is tangential to the conical configuration of the legs, and is disposed parallel and contiguous to the main portion 20. A pointed tip portion 24 of the leg which comprises a hook, extends generally radially outwardly, away from the main portion 20 at an angle "A", as shown in FIG. 2 of from 70° to about 90°, preferably 80°; which tip portion 24 is shown piercing a cava wall 26. It is critical that the outwardly extending hook or tip portion 24 extend a greater radial dimension r 2 from the center line "L" of the filter 10 that the radial dimension r 1 , which comprises the radius of the outermost end 18 from the center line "L". The contiguous main and reversibly bent portions 20 and 22 define a pad or landing which is caused to press against the inside of the cava wall 26, after the hook or tip portion 24 has pierced the cava wall 26, preventing penetration of the leg beyond the cava wall 26. This penetration, as shown by a prior art hook 30 in FIG. 3, may cause injury to the patient by movement of the hook 30 outside the cava wall 26. Without the distalmost portion of the leg comprising some form of landing, the hook may penetrate and slide directly through the cava wall. Without the hook or pointed end of the piercing element relatively normal to the wall surface, migration of the filter 10 may result, leading to extreme complications.
A further embodiment of the distal land or pad is shown in FIGS. 4 and 5, wherein a filter leg 40 has an outermost portion 42 comprised of an elongated main portion 44 and an attached segment 46, the distal ends of the attached segment 46 and the main portion 44 having a weld 48 to bind them together and preferably lie generally in the plane tangential to the conical configuration of the legs.
The attached segment 46 has a bent tip portion 50 or hook which is disposed at an angle "B" of about 70° to about 90°, preferably 80° with respect to the filter leg 40, as shown in FIG. 4. It is to be noted that the length of the tip portion 50 is similar to the tip portion 24 shown in FIG. 2, so that the end of the tip portion 50 is radially further from the longitudinal center line of the filter, than is the distalmost end (the weld 48 here) of the outermost portion 42 of the leg 40.
A further embodiment of a vena cava filter 60 is shown in FIG. 6 having an apical head 62, shown more particularly in FIGS. 7 and 8, The filter 60 includes a plurality of elongated legs 64 which are of equal length, and are configured identical to each other. The legs 64 are collectively arranged in a slightly outswept but generally conical configuration so that the legs 64 converge in the head 62, and are symmetrically spaced about a central longitudinally disposed axis "L", which is shown extending through the head 62 in FIG. 1. The legs are about 0.018 inches in diameter fabricated preferably from stainless steel, only one of the legs being described in detail.
Each leg has an outermost or distal end 66 with a hook configuration disposed thereon.
A typical leg 64 is shown further, in FIGS. 7 and 8, each mounted in a bore 68 in the apical head 62, which bore may be parallel to the center line of the filter 60. Each bore 68 receives only about 0.19 inches of the proximalmost end of each leg 64. When all the legs 64 are filling their proper respective bores 68, they are preferably welded therein. Each leg 64, in addition to having a plurality of U-shaped bends 70, disposed in the plane tangential to the cone defined by the legs 64, and intermediate their proximal and distal ends, as recited in the aforementioned incorporated patent, has a first slight bend 72 having a radius of curvature R1 of about 1.4 inches arranged immediately adjacent the apical head 62, to cause the leg(s) 64 to flare radially outwardly about 18 degrees, thus defining their cone shaped configuration, which flare of only one leg 64 is best shown in FIG. 8. This flare permits the filter 60 to have enough elastic recoil to assume its general conical configuration, which is desirable to permit the filtration of blood clots while still allowing blood to flow around the captured clots, thus promoting dissolution of any clot and maintenance of vessel patency. The filter 60 with this flare can be passed through small delivery carriers without exceeding the elastic limit of the stainless steel filter legs 64. This maintenance of the stainless steel legs 64 within their elastic limits is critical to the stress free design, such that the filter 60 can be stored (in its carrier) in a collapsed mode yet have enough of a bend when it has been ejected into a vessel so that there is adequate radially outwardly directed force to permit the hooks to penetrate the caval wall upon the ejection of the filter 60.
A second slight bend 68 having a radius of curvature R2 of about 8.4 inches is disposed along the distal one inch of each leg 64 to provide a very slight, almost unnoticeable flare primarily for utilization in the filter carrier, now shown, so as to keep the hooks biased radially outwardly, and free from entanglement with one another while they are borne in and are ejected from their carrier.
The apical head 62 on the filter 60 has a central cylindrically shaped bore 80 (diam=0.046 inches, length of cylindrical portion 0.075 inches) which is adapted to receive inself aligning engagement, a guidewire (not shown). The bore 80 critically has its cylindrical portion which is in axial alignment with the longitudinal center line "L" of the filter 60. Each end of the bore 80 has a tapered counterbore 82 to permit access of a guidewire into the bore 82. This permits the filter 60 to be aligned and centered along the axis of a guidewire in a vessel during (and after) filter emplacement therein.
Thus there has been shown a vena cava filter having an apical hub from which extends a plurality of configured legs. The legs have a particular hook formation on their distal ends, which provides a landing or pad to prevent the hooks from sliding through the cava wall and injuring the patient thereby. The legs have a further configuration of a pair of outwardly directed curves to primarily create and preserve the general conical shape of the filter after insertion into a vessel through a small delivery hole, and secondarily provide a slight flare in the distal ends of each leg to prevent entanglement of their hooks as they are being moved to their ejection site in a patient.
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A filter device positionable within a blood vessel for trapping blood clots in that vessel, the filter device comprising a head with a plurality of divergent legs each secured at its proximal end, to the head, each leg having a hook arranged at its distal end.
Each leg has a radially outwardly directed radius of curvature to create a conical configuration to the filter assembly, while distributing the stress concentration along the length of the bend, so that the elastic limit of the material, stainless steel in this embodiment, is not exceeded, and which permits compact delivery of the filter, and adequate radially directed force to permit slight hook penetration of a vessel wall.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 60/066,607, filed Nov. 26, 1997.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to oil well tools. More particularly the invention relates to proper placement of a guide stock in a wellbore for diverting tools into a lateral borehole.
2. Prior Art
When a lateral borehole is to be drilled a certain sequence of events is known and practiced regularly. First a packer is set within a primary wellbore at a location downhole of the desired exit point for a lateral borehole. A whipstock is then run and inserted in the anchor, the whipstock having an orientation sub thereon which orients the face of the whipstock in the desired direction of the proposed lateral borehole. A drill is run and the lateral borehole created. The drill is removed, the whipstock is removed and a guide stock is stabbed into the original packer. Since the guide stock is provided with the same type of orientation sub it orients in the same direction that the whipstock originally did. This is an old and well-known sequence of events and would seem to indicate that the diverter face of the guide stock should be aligned with the lateral borehole. Unfortunately, however, during the kicking off of the drill from the whipstock, the whipstock tends to move due to the tremendous torque placed on the whipstock by the drill. Since the whipstock is in this (contorted to some degree) condition when the drill leaves the primary bore the exact angle and orientation of the window thereby created is somewhat different than planned. The movement does not translate to the packer and so when the whipstock is replaced by a guide stock for feeding other tools into the lateral borehole, it may not be aligned. The orientation of the guide stock, not having any torque loads thereon is that of what was originally planned and may not coincide with the actual orientation of the lateral borehole itself. For this reason it has always been challenging to properly orient the guide stock to align with the lateral borehole.
Prior art methods for aligning the guide stock include, as the most common and ubiquitous method, experience of the drill team. More specifically, upon removing the whipstock from the hole an inspection is made which to a skilled and experienced eye will indicate about how far off the planned orientation the lateral borehole has been drilled. This is accomplished by examining marks made on the whipstock by the drill bit such as how deep the marks are, where on the diverter face the marks are located, etc. These marks tell the experienced driller where the bit bound and kicked off the whipstock diverter face and thus in which direction drilling began. From these determinations the drill team will reorient the guide stock by attaching the orientation sub to the guide stock differently. This modifies the orientation of the diverter surface so as to be more likely to be aligned with the lateral borehole. While skill and experience are of the most important assets in making a well work, the guestimate method of placing a guidestock leaves exactness to be desired.
SUMMARY OF THE INVENTION
The above-discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by the method and apparatus for placing a guide stock of the invention.
A guide stock can be reliably and precisely placed and aligned with respect to a lateral borehole by first obtaining an impression of the actual borehole window through the casing of the primary well including its exact orientation with an impression packer having an orientation sub attached thereto for engagement with the original packer installed in the primary well in preparation for drilling the lateral borehole. Upon inflation of the impression packer, the soft casing is urged into the lateral borehole opening and an impression of the window is recorded in the soft covering on the impression packer. The impression packer is then tripped out of the hole and can be reinflated at the surface to measure the impression of the lateral borehole. The impression is an exact duplicate showing angle, orientation, chord length, etc. of the window. Armed with this information a guide stock may be specifically tailored with an orientation sub and space-out subs to perfectly align with the lateral borehole. Enhancing the ability to measure the window impression is the act of scribing a line in the impression cover to employ as a reference.
In another aspect of the invention an impression packer having its own inflation reservoir is disclosed. While a standard impression packer known to the prior art may be employed in the method of the invention, certain inherent drawbacks exist. Although standard impression packers regularly function correctly, there are times when inflation is not completed or deflation is not possible. This is generally due to the employment of a rig pump at a great distance from the tool to inflate the tool and the length of the fluid column with respect to deflation. For preferred employment with the method of the invention is an impression packer having its own on-board inflation source.
The self-inflation impression packer of the invention provides more certainty that the packer will inflate to the desired pressure (approximately 200 psi) without significantly exceeding that pressure and will deflate reliably and without difficulty. The self-inflation device carries a predetermined quantity of inflation fluid which is urged into the element upon set down weight. The device automatically deflates the impression packer upon pick up. The arrangement avoids prior art inflation and deflation problems associated with pressuring up from the surface to deploy the packer. In another embodiment of the invention, the over pressure problem is avoided by installing a valve which closes at a specific predetermined pressure rating (e.g. 200 psi). A valving system is disclosed.
The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings wherein like elements are numbered alike in the several FIGURES:
FIG. 1 is a cross sectional elevation view of a primary wellbore illustrated with a drill string being deflected by a whipstock to drill a lateral borehole;
FIG. 2 is a cross sectional elevation view of the primary wellbore and lateral borehole with an impression packer installed therein;
FIG. 3 is a cross sectional elevation view similar to FIG. 2 but with the impression packer inflated;
FIG. 4 is a view of the impression packer, removed from the wellbore and reinflated to provide a representation of the drilled window in the impression rubber;
FIG. 5 is a cross sectional elevation view of the well with the guide stock installed;
FIGS. 6-11 illustrate a cross sectional view of the valve assembly of the invention in an inflation tool;.
FIGS. 12-15 illustrate a cross sectional view of the valve assembly of the invention in an alternate position;
FIGS. 16-19 illustrate a cross sectional view of the valve assembly of the invention in an alternate position;
FIGS. 20-23 illustrate a cross sectional view of the valve assembly of the invention in another alternate position;
FIG. 24 is an enlarged view of the valve of the invention;
FIG. 24A-1 is a cross sectional view taken along section line A—A in FIG. 24;
FIG. 24A-2 is the section of FIG. 24A-1 but in an alternate position;
FIG. 24A-3 is the section of FIG. 24A-1 but in an alternate position;
FIG. 24B-1 is a cross sectional view taken along section line B—B in FIG. 24;
FIG. 24B-2 is the section of FIG. 24 b - 1 but in alternate position;
FIG. 24C is a cross sectional view taken along section line C—C in FIG. 24;
FIG. 24D is a cross sectional view taken along section line D—D in FIG. 24;
FIG. 24E is a cross sectional view taken along section line E—E in FIG. 24; and
FIG. 25 is a cross sectional view of the self-inflating sub for an impression packer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1 it becomes apparent why placement of a guide stock is a difficult matter. FIG. 1 represents a primary wellbore 10 to having a packer 12 installed therein for drilling of a lateral borehole. A whipstock 14 is installed in packer 12 as is conventionally known, until this point the relative orientation of the parts is known and is relatively precise. Upon introduction of the drill string 16 however, with drill bit 18 , certainty of location and orientation is lost to some degree. Drill bits, as is known to those familiar with oil well drilling, are large and course as well as heavy and driven with incredible torque. Upon a drill bit 18 contacting the face of whipstock 14 , it gouges the face and puts tremendous downward and lateral forces as well as torsional forces on the whipstock as bit 18 kicks off to drill a lateral borehole 20 . These forces tend to distort and move whipstock 14 away from the precisely set orientation it had when installed since during drilling, the whipstock is not in the predetermined position, the lateral borehole is not being drilled precisely as it was intended to be. The degree of distortion is generally not substantial however it is sufficient to render a guide stock not properly aligned with the borehole 20 . This can and does often make installing lateral tools difficult
Referring to FIGS. 2, 3 and 4 , the method of the invention allows the rigger to gather precise information about the location and orientation of the drilled lateral borehole 20 . With this information a guide stock may be designed to align with borehole 20 exactly. The method of the invention may employ a conventional impression packer (commonly commercially available) or may employ impression packers of the invention which are disclosed in detail hereunder. In the method of the invention, prior to running impression packer 22 , the packer 22 is inflated to a circumference matching the circumference of the borehole in which it will be deployed to take an impression. In this condition a straight line is scribed where the window is expected to be (i.e. aligned with the orientation sub) on the outside diameter of the impression rubber of the packer 22 preferably the line is also painted onto the packer for ease of visibility. This is a reference line that will be employed post impression to provide an accurate measurement of the window. The line is visible in FIG. 4 . The line is preferred due to possible twisting of the packer during removal from the well. The impression packer 22 , (conventional impression packers being currently commercially available from Baker Oil Tools Houston, Tex.), is first deflated and then run in the hole with an orientation sub 24 attached to the bottom thereof which is engageable with packer 12 . The packer 22 will be conventionally run on tool string 26 . Upon landing the impression packer 22 in the packer 12 , packer 22 is inflated to a pressure in the range of from about 100 psi to about 300 psi and preferably to about 200 psi to urge the impression rubber of the packer 22 against the window 28 to create an impression in the impression rubber. It should be noted that the psi range of about 100 to about 300 with a preferred pressure of about 200 psi has been determined by the inventor hereof to create well-defined impressions of the window 28 without seriously damaging the packer 22 . Those skilled in the art will note the dramatic reduction in pressure employed from conventional use of impression packers for their originally intended purpose. More specifically, impression packers were developed to acquire impressions of casing erosion and cracking or fissures in open holes and employ a preferred working pressure of about 1000 psi. Because the window 28 being courted in the present invention is vastly larger than the features previously sought by impression packer use, the pressure had to be significantly reduced to prevent destruction of the tool including possibly bursting the inflatable element into the lateral borehole 20 . In the conventional impression packer embodiment of the invention pressure is regulated at the surface while in the new impression packers of the invention pressure is regulated downhole for more precision.
Returning to the method of the invention, packer 22 having been inflated to about 200 psi is locked off and allowed to hold pressure for a period of time of preferably at least 30 minutes. Although it is possible to obtain an impression in less than 30 minutes it is not advisable for if a viable impression is not retrieved, a significant amount of time and money will have been lost. At a time after about 30 minutes (preferably) from the time impression packer reaches about 200 psi, the packer is deflated by allowing the fluid supply to drain out of the inflatable element. Preferably about 30 minutes is allowed to drain off the conventional impression packer. Subsequent to drainage the packer 22 is removed from the well to be examined.
At the surface, packer 22 (see FIG. 4) is reinflated to a circumferential dimension equaling that of the hole in which it was set so that measurement can be made with the rubber of the inflatable element expanded to the same degree as it was when the element was inflated downhole. Preferably, and if the whipstock 14 did not move too much during drilling of the lateral borehole 20 , the scribed line 30 will be close to the center axis of the impression 32 on the impression rubber 33 . Measurements are taken, using line 30 as a reference, at approximately one foot increments to get an accurate set of dimensions of window 28 . The dimensions and orientation of the impression provide information such as the outer periphery dimensions of the window, the orientation and the distance from the original packer 12 that the window begins. These measurements are used to make up a guide stock that will align with the window.
Referring to FIG. 5, a guide stock 40 is illustrated in a position properly oriented to the lateral borehole 20 . The guide stock 40 is made up to align with window 28 exactly by adjusting the orientation of the guide stock 40 on the orientation sub 42 and providing any spacers necessary to properly place the guide stock. The setting of the original whipstock 14 has thus been adjusted to meet the alignment requirements of borehole 20 occasioned by the forces of drilling on whipstock 14 as discussed previously. All measurements are provided accurately by impression 32 to perfectly align guide stock 40 with borehole 20 when guide stock 40 is stabbed in packer 12 .
Preferably the impression packer 22 is long enough to provide an impression surface that will cover the entire window 28 with one impression. It is possible, however, to employ more than one impression packer for different areas of the window. By changing the length of space-out subs on the impression packer, different areas of the window may be queried. All of the impressions can then be recombined at the surface by measurement of distance from the packer 12 which is known. A single packer 22 long enough to cover the window is preferable due to a shorter period of time necessary to obtain the whole impression, less calculation work and fewer opportunities for error with a single impression.
With respect to the impression packer itself, referring to FIGS. 6 through 25, two embodiments of the invention are illustrated. In the discussion above, possible difficulties with conventional impression packers were noted such as problems associated with inflation and deflation. Another possible problem while employing conventional impression packers in the method of the invention is an over pressure situation. Keeping in mind the low pressures at which the method of the invention is effective, as set forth above, one of skill in the art will readily recognize the potential for an over pressurization situation where the element may rupture or other damage could occur. Over pressurization may be exacerbated by a long fluid column above the device which makes accurate pressurization difficult. Thus the invention discloses two embodiments of impression packers which reduce or avoid any over pressurization potential.
In a first embodiment; illustrated in FIGS. 6-24E, a conventional impression packer is modified by the addition of a pressure sensitive valve. The valve is intended to close at the time the pressure of fluid internal to the impression packer is at or about 200 psi. Once the valve is closed fluid pressure from the column, or ultimately the surface, will not be added to the interior of the packer. With this safety feature, over pressurization concomitant a surface fed system is unlikely. The valve is preferably mechanically actuated by providing a port open to internal element pressure and to a closure valve assembly whereby internal element pressure upon overcoming the bias of a spring closes the valve. This is designed to occur at about 200 psi. It should be noted that the valve may also be electromechanically or electrically actuated and may be associated with downhole sensor(s) and a processor of other type or controller.
In a second embodiment of the impression packer of the invention, reference being made to FIG. 25, over pressurization is virtually impossible due to the inflation fluid being carried within an inflation tool connected to the impression packer itself. Set down weight on the packer causes shearing of a retaining member whereafter the set down weight forces fluid out of a reservoir and into the element. The amount of fluid contained in the reservoir is sufficient only to create an internal pressure within the impression packer of about 200 psi. Picking up on the device creates an opposite reaction and draws fluid back into the reservoir thus deflating the element.
In FIG. 25, the reservoir is identified by numeral 82 . Reservoir 82 is bounded by housing 80 circumferentially, inflation sub 84 at the downhole end threaded into housing 80 , piston 86 at the uphole end, fluid sealingly slideable within housing 80 and washover pipe 88 centrally. As is then apparent, reservoir 82 is annular. Piston 86 is slidable within housing 80 to either expel fluid from the reservoir or draw fluid back in similar to a hypodermic needle. Piston 86 is operated through movement of mandrel 90 which is coaxially located within housing 80 . Mandrel 90 is supported radially, preferably by a plurality of torque bearings 92 arranged circumferentially therearound although it should be understood that other support structure could be substituted. The torque bearings number preferably six, but more or fewer may be employed if desired. Torque bearings 92 ride in semicircular grooves 94 in mandrel 90 and are maintained in contact with mandrel 90 by being held into holes 96 in top sub 98 with set screws 100 . Mandrel 90 terminates at the uphole end thereof preferably with a box thread connector 102 for connection a to tubing string (not shown). It should be noted that the stroke of piston 86 is preferably from top sub contact face 97 to the uphole end of pin thread 104 where housing 80 connects to inflation sub 84 .
During run in, reservoir 82 is filled with an amount of fluid appropriate to fill the selected size of the impression packer to about 200 psi and to the predetermined circumference (equal to the hole in which the packer will be inflated). Mandrel 90 is prevented from moving piston 86 during run in by a shearable connection. The connection is preferably at least two shear screws 106 . Upon set down, however, of the orientation sub for the impression packer, screws 106 are sheared and the fluid in reservoir 82 is urged through the several inflation ports 108 by piston 86 due to downward movement of mandrel 90 . When the piston 86 has fully stroked, the fluid displaced from reservoir 82 into the impression packer is the quantity of fluid that will create about 200 psi in the packer. The movement is caused by additional set down weight from the tubing string above. The fluid is expelled from reservoir 82 through inflation ports 108 and into the impression packer connected to the self-inflating device of the invention. The inflation ports 108 are preferably drill holes through inflation sub 84 . Preferably at least two are provided. Inflation ports 108 remain in open fluid communication with the inflatable element of the impression packer. This is important because it provides for automatic deflation of the packer as well as inflation. More specifically, upon picking up on mandrel 90 , piston 86 moves uphole and creates a vacuum within reservoir 82 which draws fluid out of the impression packer causing it to deflate. By the time the pick up force reaches the 30-40 thousand pounds to disengage the orientation subs on the impression packer, the mandrel 90 is in its fully extended position, piston 86 has been stroked fully uphole within the tool and all of the fluid in the inflatable element has been removed. The tool then can be easily tripped out of the wellbore for examination as discussed hereinabove.
While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.
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A method for locating placement of a guide stock in a multilateral well wherein the guide stock is properly aligned with the lateral borehole. The method employs an impression packer with a scribed reference line to provide information at the surface regarding the lateral borehole's exact location and orientation with respect to the originally installed whipstock packer. This information is then employed to make up a guide stock and orientation sub to properly orient the diverter face of the guide stock with the lateral borehole. There are tool embodiments for inflating the impression packer to a preset relatively low internal pressure. In one embodiment, the inflation fluid is carried downhole in the tool and is released to the packer on set down pressure, the fluid being drawn back out of the packer upon pick up. In another embodiment, the impression packer is outfitted with an automatically closing valve. The valve can be mechanically electromechanically or electrically activated and may work in combination with a controller.
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CROSS REFERENCE TO RELATED APPLICATIONS
Pursuant to 35 U.S.C 119(e) Applicant claims the benefit of U.S. Ser. No. 60/165,751 filed Nov. 16, 1999, a 35 U.S.C. 111(b) Application.
CONTRACTUAL ORIGIN OF THE INVENTION
The United States Government has rights in this invention pursuant to Contract No. DE-AC36-99GO10337 between the United States Department of Energy and the Midwest Research Institute.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to hydrogenated amorphous silicon materials, and, in particular, it relates to a method of making hydrogenated amorphous silicon films which are characterized by an improved stability to metastable degradation and useful in amorphous silicon devices.
2. Description of the Related Art
An amorphous silicon device, such as a silicon solar cell, is comprised of a body of hydrogenated amorphous silicon (a-Si:H) material, which can be formed in a glow discharge of silane or other chemical vapor deposition techniques. Such cells can be of the type described in U.S. Pat. No. 4,064,521 entitled: Semiconductor Device Having a Body of Amorphous Silicon, issued to D. E. Carlson on Dec. 20, 1977. Amorphous hydrogenated silicon based device technology is currently the leading candidate for large area, low-cost photovoltaic applications.
For solar cells, the basic device structure is a single p-i-n junction or an n-i-p junction in which all layers are traditionally amorphous and are made in a continuous plasma deposition process. The substrate of the solar cell can be made of glass or a metal, such as aluminum, niobium, titanium, chromium, iron, bismuth, antimony or steel. A metallic contact can be formed on the back of the substrate.
However, since its discovery in 1977, a distinct disadvantage in application of these materials in devices has heretofore been the problem of light-induced metastability of the a-Si:H films themselves. See, Staebler, D. L. and Wronski, C. R., Appl. Phys,. Lett., 31, 1977, 292. Briefly, the exposure of device-quality a-Si:H films to light or excess carriers results in an increase in the density of neutral threefold-coordinated dangling-bond (DB) defects by one to two orders of magnitude. The excess in defects reduces carrier lifetimes and photoconductivity in the films which sharply limits the usefulness of a-Si:H as an inexpensive semiconductor material.
A new model of light-induced metastability (Staebler-Wronski effect) in a-Si:H has more recently been disclosed. There, it is postulated that when two mobile H atoms, generated by photo-induced carriers, collide they form a metastable-immobile-complex which contains two Si—H bonds. Excess metastable dangling bonds remain at the uncorrelated sites, from which the colliding hydrogen molecules were excited. This quantitative model accounts for many of the experimental observations which relate to the microscopic nature of the degradation problem and the associated kinetics of light-induced-defect-creation under various conditions. See Branz, H., Solid State Communications, Vol. 105, No. 6, pp. 387-391, 1998.
It is well known that the light-induced DB defects are metastable because they can be reversed. In the prior art, one method of reversing metastability includes annealing the films for 2 hours at temperatures greater than 150° C. Another way of annealing light-induced changes in the dark conductivity and photoconductivity of a-Si:H thin films involves the ultraviolet (UV) irradiation (wavelength≅254 nm) of the films at room temperature. With this annealing process, a problem exists in that although the bulk photoconductivity of the film is improved, the UV irradiation is mostly absorbed near the top surface of the films and causes considerable surface damage. G. Ganguly, et al., Appl. Phys. Lett. 55, 1975 (1989). Further, illumination will cause Staebler-Wronski degradation of all amorphous silicon after such reversal treatments. Thus, what is needed is a process which, unlike the foregoing reversal methods, produces device-quality a-Si:H films which are highly resistant to metastable degradation without deleterious surface damage and thereby demonstrate an improvement in stability under light exposure or excess carrier conditions when used in amorphous silicon devices.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide novel hydrogenated amorphous silicon films which are characterized by an improved resistance to metastable degradation.
It is another object of the invention to provide a novel method for producing device-quality a-Si:H films which are highly resistant to metastable degradation and thereby demonstrate an improved stability when exposed to light or excess carriers.
It is yet another object of the invention to provide amorphous silicon devices which, through use of the novel a-Si:H films made according the method herein, are characterized by an improvement in stability when used under light or excess carrier conditions.
Briefly, to overcome the problems associated with the prior art methods and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention is intended to provide a method of producing amorphous hydrogenated silicon films which are resistant to metastable degradation, the method comprising the steps of growing a hydrogenated amorphous silicon film, the film having an exposed surface, illuminating the surface using an essentially blue or ultraviolet light to form high densities of a light induced defect near the surface, and etching the surface to remove the defect.
Additional advantages of the present invention will be set forth in part in the Id description that follows and in part will be obvious from that description or can be learned from practice of the invention. The advantages of the invention can be realized and obtained by the method particularly pointed out in the appended claims.
DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and which constitute a part of the specification, illustrate at least one embodiment of the invention and, together with the description, explain the principles of the invention.
FIG. 1 is a flow diagram of the process according to the invention.
FIG. 2 is a graph showing an improvement in the stability of an a-Si:H film prepared using the process of the invention.
FIG. 3 is a schematic diagram of a Schottky barrier photovoltaic cell having an amorphous hydrogenated silicon material made according to the method herein and deposited on a stainless steel substrate in accordance with Example 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Unless specifically defined otherwise, all technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described.
The invention provides a process for improving a-Si:H stability by increasing the density of metastable two-hydrogen complexes without simultaneously increasing the dangling-bond density. Referring now to the drawing figures, in FIG. 1 it is shown generally at 10 a device comprised of an a-Si:H film 2 deposited on a suitable substrate 4 , such as glass. The film 2 may be incorporated into a solar cell, transistor, sensor or any other device utilizing a-Si:H or it may be an alloy based on a-Si:H, such as a-SiGe:H or a-SiC:H. The device 10 may be prepared according to any method well known in the art. For example, a-Si:H devices 10 may be prepared by the glow discharge decomposition of 10 sccm of pure silane at a chamber pressure of 0.3 Torr with radio frequency power of 5 W (13.56 MHz frequency) onto substrates 4 held at 250° C. Metal contacts 3 are also provided for measurement of photoconductivity.
An excess metastable (M(Si—H) 2 ) region 2 c is created using illumination of the a-Si:H film layer 2 with blue or ultraviolet light 5 , as shown through cross section A of the device 10 . The illumination step increases the dangling-bond density in damaged region 2 a , but, at the same time, gently drives excess mobile hydrogen 2 b into the bulk of the film 2 where it passivates dangling-bonds and forms the two-hydrogen complexes M (Si—H) 2 in the bulk region 2 c . An etching step is then used to remove the damaged surface layer 2 a , leaving behind a hydrogen-enriched film 2 c . The illumination and etch steps may be repeated many times, and can be done either in a deposition chamber or outside it after deposition of the film 2 itself.
In some applications the film must be carefully handled subsequent to the ultraviolet light illumination processing step. For example, annealing for about 1 hour at 200° C. or more will cause hydrogen to redistribute within the film, and this redistribution of hydrogen will annul the improvements achieved with the ultraviolet-light-illumination and etch steps, according to the method of the invention. Moreover, when using the film in device applications, thermal treatment of the doped contacts or other layers subsequent to the illumination and etch steps is desirably limited to temperatures in a range of less than 150° C.
Referring again to FIG. 1, when a film prepared according to the method of the present invention is used under illumination conditions, mobile hydrogen 2 c is released from the metastable two-hydrogen complexes, and this release stabilizes the material against excessive metastable dangling bond formation (Staebler-Wronski effect).
The following examples illustrate the manner in which the amorphous hydrogenated silicon materials in accordance with the method of the present invention can be made and used in device quality applications.
EXAMPLE 1
Referring once again to FIG. 1 a device 10 having an a-Si:H layer 2 approximately 4800 Å in depth was cut in half along cross section A. One half of the sample was illuminated for 40 minutes with about 38 mW/cm −2 of UV light obtained from a Hg—Xe compact arc lamp light source filtered through a 335 nm filter with a 100 nm wide band pass. The other half of the sample was used as the control without illumination. Each half was then etched in a 20% solution of NaOH in water for about 3 minutes in order to remove the upper 700 Å of the surface, leaving an a-Si:H layer(s) 2 c of approximately 4100 Å. The layers 2 c were illuminated continuously by 100 mW/cm −2 of red light from a white source filtered by a 650 nm filter with a 100 nm wide bandpass. Periodic photoconductivity measurements were made under this same red light.
FIG. 2, the photoconductivity (S/cm) for each of the above samples is graphically illustrated as a function of time. The dashed line represents the measured results for the UV illuminated sample, and the solid line represents the control results. From this graph, it is easily observed that the UV illuminated and etched sample was more stable over time.
EXAMPLE 2
This example illustrates an improved resistance, measured as the function of open-circuit voltage, to metastable degradation under light-soaking conditions using Schottky barrier photovoltaic cells. Referring now to FIG. 3, it is shown generally a schematic diagram of the Schottky cell 20 as deposited on a stainless steel substrate 21 . Here, a 500 Å thick n-layer 22 was deposited using plasma-enhanced chemical vapor deposition (PECVD) from PH 3 , H 2 and SiH 4 source gasses. A 3000 Å thick i-layer 23 was also PECVD deposited from a SiH 4 source gas. A portion of this thin film 23 was then treated with ultraviolet light for 1 hour using the light source and intensity conditions set forth above. Then, an overlapping portion of the sample surface was etched in a 20% solution of NaOH in water for about 1 minute to remove about 700 Å from the top i-layer 23 surface. A portion of the sample which was not etched had been treated with ultraviolet light in order to serve as an experimental control. Semitransparent Pd top-contacts 24 , having a thickness of about 140 Å, were then deposited on all regions of the film to complete the Schottky photovoltaic devices 20 of FIG. 3 .
Many of the devices 20 were then measured, before and after a 3 day of light soaking condition, with about 100 mW/cm of white light from a multi-vapor metal-halide lamp source. After deposition, all devices which had not been exposed to the ultraviolet light illumination step had an open-circuit voltage of 0.48 to 0.49 under 1 sun of white illumination. The ultraviolet illuminated and etched devices were inferior, having voltages in the range of about 0.44 to 0.46. After illumination stress, all devices which had not been exposed to ultraviolet light showed an approximately 0.47 volts due to the Staebler-Wronski degradation effect. However, devices treated with the ultraviolet light illumination and etch steps, according to the method of the invention, actually demonstrated an improvement upon subsequent light soaking, to about 0.49 volts. These results demonstrate that the expected improvement in stability was due to the ultraviolet and etch treatment steps, in sequence, according to the method of the present invention.
While the present invention has been illustrated and described with reference to particular structures and methods of fabrication, it will be apparent to those skilled in the art that other changes and modifications can be made therein, within the scope of the present invention as defined by the appended claims.
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A method of producing a metastable degradation resistant amorphous hydrogenated silicon film is provided, which comprises the steps of growing a hydrogenated amorphous silicon film, the film having an exposed surface, illuminating the surface using an essentially blue or ultraviolet light to form high densities of a light induced defect near the surface, and etching the surface to remove the defect.
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BACKGROUND OF THE INVENTION
This invention relates to electric lamps and, more particularly, to a fuse wire for an electric lamp.
In the manufacture of electric lamps e.g. incandescent lamps, fuses e.g. of monel or nickel D wire are installed to interrupt excessive current flow therethrough to protect the lamp from damaging electric arcing. However upon filament failure and fuse burnout, one or more internal base arcs can develop, which can melt a hole through the lamp base and/or weld such base to the lamp socket with attendant risk of fire and personal injury.
To reduce such arcs, manufacturers have found it necessary to fill the lamp base with one or more insulative (sometimes porous) cement layers in an attempt to insulate the inside conductive surface of the base shell from fuse wire arcing. This type of solution requires additional steps in lamp manufacture and considerable expense and such base melt-through, though reduced, continues. For an example of a lamp base substantially filled with foamed cement, see U.S. Pat. No. 4,216,406 to Bjorkman et al. (1980).
A further shortcoming of the above conventional fuse wires is that in order to serve as a fuse for various lamps, e.g. 15 to 100 watts and higher, especially at 220 V to 245 V such fuse wires must be of a small diameter e.g. about 0.16 mm. Such small wire sizes are extremely difficult to handle in an automatic lamp production process, as the wire tends to kink and foul up under high speed machine manipulation.
Accordingly, such prior lamp fuses have not been satisfactory and there is a need and market for an improved lamp fuse which substantially overcomes the above prior art shortcomings.
By monel fuse wire as used herein is meant fuse wire of nickel/copper alloy in proportions well known in the art, e.g. a typical fuse wire material is monel 400 having a composition of nickel 63-70%, carbon 0.3% max., manganese 2.0% max., sulfur 0.24% max., silver 0.5% max. and a remainder of copper. All percentages noted herein are by weight unless otherwise stated.
SUMMARY OF THE INVENTION
Accordingly it is an object of the present invention to provide an improved fuse wire for an electric lamp which, upon fuse burnout, significantly reduces lamp base arcing.
It is a further object of the invention to provide an improved lamp fuse wire which is more compatible to high speed processing by machinery or equipment in lamp production.
These and other objects and advantages are accomplished in the present invention which provides in an electric lamp having a light-transmitting envelope containing an energizable source of light, a base secured to the envelope, a plurality of lead-in wires extending through the envelope and electrically connecting the light source to terminal means of the base, and an improved fuse wire included as at least a portion of one of the lead-in wires. The improved fuse wire comprises a material selected from the group consisting of a first alloy of 15% to 25% Cr, 70% to 80% Fe and 4.5% to 5% Al, which alloy is designated herein as Aluchrom, and a second alloy of 20% to 25% Cr, 20% to 30% Ni and 45% to 55% Fe, which alloy is designated herein as Cronifer. Aluchrom and Cronifer are alloy designations in Europe; e.g., Aluchrom is available from Vereinigte Deutsche Metallwerke A.G., Altena, West Germany. In the United States, an alloy similar to Aluchrom is available under the designation Alchrome from Wilbur B. Driver Co.
In the preferred embodiment, the improved fuse wire of the invention has a diameter of between 0.18 mm to 0.22 mm., though such diameter can be larger or smaller within the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will become more apparent from the following detailed description and drawings, in which;
FIG. 1 is a fragmentary elevation view, partly in section, of a prior art incandescent lamp;
FIG. 2 is an elevation view, partly in section, of an incandescent lamp embodying the present invention;
FIG. 3 is an elevation view, partly in section, of another incandescent lamp embodying the present invention; and
FIG. 4 is a graph illustrating certain characteristics of an improved fuse wire in a lamp embodying the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring in more detail to the drawings, FIG. 1 shows a portion of a prior art incandescent lamp 10 having a light-transmitting, bulbous glass envelope 12 secured to base 14, which includes a metal shell 15, an insulative plug 16, and a center contact 18. Within the lamp, lead-in wires 20 connect with and support a coiled filament at both ends thereof (not shown). Each lead-in wire 20 includes an intermediate wire segment 22, e.g, of Dumet wire, which extends through and is sealed into the press on reentrant glass stem portion 23 of envelope 12. The outer ends of the wire segments 22, within the hallow of stem 23, are then connected to respective fuse wires 24 of e.g., monel, which in turn are connected to center contact 18 and the upper rim of base shell 15, respectively, as shown in FIG. 1. To lessen the problem of internal base arcs upon burnout of one or both of the fuse wires 24, the screw base 14 is filled with a quantity of insulative base cement 26, as shown in FIG. 1. However an internal base arc and melt-through can still develop upon fuse burnout with the above described consequences e.g. where a 0.16 mm dia. monel fuse wire is employed in lamps of 15 W to 100 W at 220 V to 245 V.
A pair of incandescent lamps, having improved fuse wires according to the present invention, are illustrated in FIGS. 2 and 3. Lamp 30 of FIG. 2 has a light-transmitting, bulbous glass envelope 32 cemented to a typical screw base 34. Mounted within the envelope 32 is an energizable light source comprising a coiled filament 36, e.g., of tungsten, which is held by support wires 38, which are in turn mounted on a glass button rod 40 extending from a reentrant stem mount (or flair tube) 42, as shown in FIG. 2. The flare portion of the stem mount is sealed about the bottom periphery of the bulb portion of envelope 32, and the envelope, which contains an inert gas such as a mixture of nitrogen and argon, is hermetically sealed by tipping off exhaust tube 37. Electrically connected to each end of the filament 36 are lead-in wires 44 and 46, which on the interior of the envelope are typically of nickel or nickel-plated copper. These nickel wire segments respectively connect in turn to Dumet wire segments 45 and 47, which extend through and are sealed into stem press 42a. Dumet wire 45 is, in turn, connected with a fuse wire 46 of the invention, and the other end of fuse wire 46 is electrically connected, such as by solder, to center contact 50 of base 34. The Dumet wire 47 connects with a fuse wire 48 of the invention, which in turn is connected, such as by soldering, to the upper rim of metal screw shell 35 of base 34. The external base terminals comprising shell 35 and contact 50 are electrically isolated by insulative plug 52.
Alternatively, only one of the lamp lead-in wires may be fused, as is typical in the United States; for example, the lead-in wire 46 would be unfused whereupon the wire segment 48 connected to shell 35 could be, say, copper instead of a fuse wire material. Cement 33 bonds the bottom neck portion of envelope 32 to the metal shell 35 of base 34 as shown in FIG. 2. However there is no need to add insulative filler material within the remaining hollow interior of the base shell 34, due to the composition of the novel fuse wire 46 (and 48) as described below.
In another lamp with improved fuse wires embodying the invention, incandescent lamp 60 having a glass envelope 62 cemented to a double-contact bayonet-base 64, is shown in FIG. 3. The filament 66, the internal support structure 68 and the three-part lead wires 70 and 72 can be of the same structure and materials as those discussed above with respect to lamp 30 of FIG. 2., except that the three-part lead wire 72 includes a fuse wire 74 of the invention which is electrically connected, such as by soldering, to a contact 76, and the three part lead wire 70 includes a fuse wire 78 of the invention which connects with a contact 80, both of which contacts are mounted upon an insulative plate 82 for providing electrical isolation therebetween. Plate 82 is mounted in turn to the bayonet base 64 side shell, as shown in FIG. 3. The flared stem portion of support structure 68 is sealed about the bottom periphery of envelope 62, and the inert gas-filled envelope is hermetically sealed by tipping off the exhaust tube of structure 68. The bottom neck portion of envelope 62 and the bayonet base shell 64 are adhered together by cement 83. Again however, there is no need to add insulative filler to the remaining hollow interior of the bayonet base shell 64, due to the composition of the fuse wires of the invention, which composition is described below.
In designing the improved fuse wires of the invention, consideration was given to determining a material and wire diameter to provide a proper fusion time so that the fuse wire would generally not blow (produce an open circuit) during the inrush current at lamp switch-on but would trip (open circuit) prior to any significant increase in bulb pressure due to gas heating from the fuse failure arc. Another design consideration was to provide fuse wires of sufficient diameter to be reasonably processed by production machinery or equipment in lamp manufacture.
It was discovered that the preparation of fuse wires of Aluchrom, of the composition described hereinbefore, and fuse wires of Cronifer, of the composition described hereinbefore, meet the above design considerations. In addition, the improved fuse wires of the invention do not require the addition of insulative filler material to protect the interior of the lamp base shell. However, insulative filler can be added to the interior of a lamp base in combination with improved fuse wires of the invention, as desired, within the scope of the invention.
Further it was found that the energy rating of the fuse wires of the invention is such as to permit use of thicker wires than the prior art, e.g., monel wire, and yet maintain an equivalent energy rating therefor, which rating is more fully described below. Such prior art wires are required to be of small diameter e.g., about 0.16 mm for a monel fuse wire to act as a fuse. The improved fuse wires of Aluchrom or Cronifer can be larger in diameter and serve as a proper lamp fuse as tabulated below:
Aluchrom fuse wire: 0.20 mm to 0.22 mm
Cronifer fuse wire: 0.18 mm to 0.19 mm
Such fuse wires of the invention, though larger in diameter than, e.g., the Monel wire, are equivalent thereto in fuse energy rating as stated above. However the Aluchrom and Cronifer fuse wires, upon fuse burnout, more quickly extinguish internal base arcs that develop than their prior art counterparts, which results in less burnout of the lamp base shell as tabulated below.
A useful criterion for evaluation of fuse wires having different diameters is a plot of I 2 t against different fuse wire materials of various diameters. Accordingly, I 2 t is related to d 4 and plotted against diameter on a log--log graph to compare the energy rating for various diameter fuse wire materials, as shown in FIG. 4; where I is current, t is time and d is diameter and I 2 t is an energy rating for burnout of fuse wires at a comparable time and comparable arc (lamp failure) current. On such graph, plot line 90 represents the plotted data for a monel fuse wire with diameter 0.15 mm; plot line 92 represents the data for a monel fuse wire with diameter 0.16; and plot line 94 represents the data for Aluchrom fuse wire with diameter 0.20 mm. The circle points with vertical and horizontal extension lines represent the measurement points, whereas the remainder of the plot lines are extrapolated. As shown in the graph, larger diameter Aluchrom fuse wires have I 2 t ratings that are equivalent to those of smaller diameter monel fuse wires. For example an Aluchrom fuse wire having a diameter of 0.20 mm has an I 2 t rating equivalent to a monel fuse wire having a diameter of about 0.16 mm, as evident from examining FIG. 4. Specific examples of Cronifer and Aluchrom alloys employed in the improved fuse wires of the invention are as tabulated below in Table I.
TABLE I______________________________________Fuse Wire AlloysComposition By Weight Percent Cronifer Cronifer Alu- Alu- Alu- III Extra IV Extra chrom O chrom I chrom WCompo- NiCr CrNi CrAl CrAl CrAlnents 30 20 25 20 25 5 20 5 15 5______________________________________Cr 20 25 25 20 15Ni 30 20 -- -- --Fe Remain- Remain- Remain- Remain- Remain- der der der der derAl -- -- 5 5 5______________________________________
An important physical property of fuse wires is the electrical resistance thereof. The resistivity of various fuse wire alloys discussed herein, at 20° C., is as follows:
______________________________________Monel 400 51 micro-ohm-centimetersAluchrom O (or Alchrome D) 144 micro-ohm-centimetersAluchrom W (or Alchrome 750) 125 micro-ohm-centimetersCronifer IV Extra 95 micro-ohm-centimeters______________________________________
Tests were conducted to determine the performance of four groups of test lamps of 50 or more lamps per group, which groups had fuse wires as specified below. All of these test lamps were energized on a 10% over-voltage supply to see if the inrush current would blow any of the respective fuse wires. No lamp fuse wire exhibited this type of failure.
Another performance test, the "Schaffner test" was conducted on the above four groups of lamps. The test was conducted to see if any of the test lamps exploded or exhibited base arcing, i.e. an arc during the burnout of the filament upon fuse wire failure between one or more of the fuse wires and the base shell. Such arc, as previously discussed, can melt holes in the base shells of e.g., aluminum or brass. During such tests, no lamp explosions were noted. However base arcing holes in lamp base shells in various groups of the test lamps were recorded as follows in Table II.
TABLE II______________________________________225 V 100 W:Fuse Wire Number of Arc Holes in PercentAlloy Wire Dia. Lamps Base Shell Failure______________________________________Aluchrom O 0.20 mm 163 17 10.4Monel 0.20 mm 78 30 38.5Aluchrom O 0.22 mm 50 7 14.0Cronifer 0.20 mm 72 17 23.6______________________________________
As shown in the foregoing Schaffner test, the lamps with fuse wires made of Aluchrom or Cronifer, upon fuse burnout, exhibited considerably less melt holes or base failure than did lamps with the prior art, e.g. monel, fuse wires. As indicated, the monel fuse wires in the lamps tested were 0.20 mm dia. Had monel fuse wire of 0.16 mm dia. been employed in some of the test lamps, the failure percentage might have been smaller, but an insulated filler would still have been desirable in the shell, and such thin or small diameter wire is difficult to process through lamp production machinery as previously stated.
Accordingly, fuse wires made with Aluchrom or Cronifer alloys, of the present invention are easier to process by lamp-making machinery, do not require insulative filler for the lamp base shells, and provide lamps with a considerably greater safety factor upon lamp failure and fuse burnout.
While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims. For example, fuse wires according to the invention can also be useful in 120 volt incandescent lamps, such as commonly used in the United States, in which case only one of the lead-in wires may be fused. Further, the fuse wire can be used in lamps having one or more filaments, each connected to a respective pair of lead-in wires having one or both wires fused, and various types of filaments may be used, such as straight, coiled or coiled-coil. Also, alloys with similar compositions and resistivities can be employed as the fuse wire material; e.g., the aforementioned Alchrome D and Alchrome 750 alloys.
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In an incandescent lamp having a glass envelope joined to a base member and a filament mounted within the envelope, an improved fuse wire comprises a portion of one or both of the lead-in wires connecting the filament to the base member. The fuse wire is made of an Aluchrom alloy containing Chromium, Nickel and Iron, or is made of a Cronifer alloy containing Chromium, Iron and Aluminum. The Aluchrom or Cronifer fuse wire, upon lamp failure and fuse burnout, exhibits reduced arcing melt-through of the lamp base compared with lamps having prior art fuse wires, for improved safety thereof.
Further the Aluchrom or Chronifer fuse wires have an I 2 t energy rating which permits the use of larger diameter fuse wires which can more readily be processed by lamp production machinery than the smaller diameter lamp fuse wires of prior art materials.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a 371 National Stage Application of PCT/EP2012/003452, filed Aug. 13, 2012. This application claims the benefit of European Application No. 11007670.0, filed Sep. 21, 2011, which is incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an apparatus, a system and a corresponding method for reading out X-ray information stored in storage phosphor panels.
[0004] 2. Description of the Related Art
[0005] The storing of X-rays penetrating an object, for example a patient, as a latent image in a so-called storage phosphor panel constitutes an option for recording X-ray images. In order to read out the latent image, the storage phosphor panel is irradiated with stimulating light and thereby stimulated to emit emission light. The emission light, the intensity of which corresponds to the image stored in the storage phosphor panel, is detected by an optical detector and converted into electrical signals. The electrical signals are further processed, as required, and finally made available for analysis, in particular for medical-diagnostic purposes, by transmitting them to a corresponding output device, such as for example a monitor and/or a printer.
[0006] In prior art apparatuses and systems, electromechanical actuators, mostly driven by electrical motors, are provided for locking and/or opening the cassette which has been inserted into the apparatus or the system containing the storage phosphor panel to be read out.
SUMMARY OF THE INVENTION
[0007] The problem addressed by the present invention is to provide an apparatus, a system and a corresponding method for reading out storage phosphor panels, the apparatus, system and method assuring a locking and/or opening of the inserted cassette that is as reliable as possible, while providing a straightforward structure.
[0008] Preferred embodiments of the present invention provide an apparatus, a system and a method as described below.
[0009] The apparatus according to a preferred embodiment of the present invention comprises an input device into which a cassette containing a storage phosphor panel can be loaded, and a read-out device in which the storage phosphor panel is irradiated with stimulating light and in which the emission light which is thereby stimulated in the storage phosphor panel can be captured, and is characterized by at least one mechanical element which can be driven mechanically by a movement of the cassette when the latter is being loaded into the input device and which can thereby lock and/or open the cassette in the input device.
[0010] Apart from the apparatus, a system according to a preferred embodiment of the present invention comprises a cassette for receiving a storage phosphor panel.
[0011] A method according to a preferred embodiment of the present invention comprises the following steps: loading a cassette containing a storage phosphor panel into an input device and irradiating the storage phosphor panel with stimulating light and thereby capturing the emission light which is thereby stimulated in the storage phosphor panel, and is characterized in that at least one mechanical element is mechanically driven by a movement of the cassette when the latter is being loaded into the input device and thereby locks and/or opens the cassette in the input device.
[0012] Preferred embodiments of the invention are based on the thought that one or more mechanical elements that are driven or actuated solely by loading, in particular sliding, the cassette into the input device, keep the cassette in the input device and/or unlock and/or open the closure of the cassette. The mechanical energy for driving the mechanical elements hereby originates substantially from respectively the force or energy exerted by the operator when loading, in particular sliding in, the cassette. Maintaining, unlocking and opening the cassette hereby take place purely mechanically, for example, by using mechanical stops, latching devices, levers and tension springs, and without the electromechanical drives which are otherwise usually applied, such as electrical motors, electromagnets, relays or the like. The respective mechanical processes for maintaining, unlocking and opening the cassette are hereby triggered solely by loading the cassette—and in particular without light barriers or other detectors —, so that in this context it can also be considered a self-triggering mechanism. Analogously to the purely mechanical locking of the cassette and/or respectively the unlocking and opening of the closure of the cassette, the mechanical elements of course also allow a purely mechanically driven closing and unlocking of the closure respectively the unlocking and release of the cassette by an operator removing the cassette from the input device.
[0013] Preferred embodiments of the present invention allow to completely omit the electromechanical components which are usually employed for loading, unlocking and opening the cassette, which significantly simplifies the structure of apparatuses and systems and simultaneously allows, not least because of the associated reduction of the susceptibility to failure, a particularly reliable locking, unlocking and opening of the loaded cassette.
[0014] Preferably, the movement of the cassette being loaded into the input device is a movement carried out by an operator, in particular a translatory motion. As a result, additional electromechanical drives or the like can also be omitted when generating the movement of the cassette.
[0015] Moreover, it is preferred that at least one lever or a lever system is provided as mechanical element, whereby the movement of the cassette being loaded is able to bring the lever (system) into a position in which the lever or lever system locks the cassette in a predetermined position. To that end, elements, for example protrusions, can be provided on the lever or lever system that can engage in corresponding elements on the cassette, for example grooves, when the movement of the cassette displaces the lever or lever system in a closer position to the cassette. To that end, a reliable locking of the cassette is realized in a simple way.
[0016] In a further preferred embodiment, the mechanical element is provided in the form of at least one unlocking element which can be brought into a position, by the movement of the cassette being loaded, in which the unlocking element can unlock a closure provided at the cassette, in particular a pivotable cover flap. The unlocking element can, for example, be a bolt that is able to actuate a locking mechanism located in or on the cassette for locking and unlocking the cover flap. Thanks to this, the locking and unlocking of the closed cover flap of the cassette can also be realized in a simple and reliable way.
[0017] Preferably, the mechanical element is provided in the form of at least one opening element which can be brought into a position, by the movement of the cassette being loaded, in which the opening element can open a closure provided on the cassette, optionally only after the closure being unlocked by the unlocking element described above. The opening element can, for example, have the form of a pivotable gripper that engages on or in the closure of the cassette, that is pivoted by a position by the movement of the cassette and that thereby shifts the preferably pivotable closure into an open position. This allows achieving a reliable opening of the cassette by using simple mechanical device.
[0018] In a further preferred embodiment, a locking mechanism is provided which can lock the mechanical element(s) in the position in which they respectively lock the cassette in the predetermined position and unlock and open the closure, and can unlock the mechanical element(s) again from the position, i.e. release it (them) from the position. The mechanical elements are hereby kept in their respective functional position in a simple and reliable way, without additional, optionally electromechanical, devices being required.
[0019] Moreover, it is preferred to provide at least one tensioning element, in particular a tension spring or pressure spring, that pretension(s) the mechanical element(s) in the position in which, respectively, the cassette is locked in the predetermined position and the closure is unlocked and opened. This has the advantage that the mechanical elements, while the cassette is being removed from the input device, return by themselves into their original position and thereby respectively cause an automatic unlocking of the cassette and an automatic closing and locking of the closure.
[0020] A further preferred embodiment provides that the input device comprises a support and a carriage that is able to receive the cassette and that can be moved, together with the cassette it has received, relative to the support. Preferably, the carriage is movably mounted on the support. Moreover, it is preferred that the at least one mechanical element is provided on the carriage and can be moved, together with the carriage, relative to the support. One or more of the measures allow to realize the drive and in particular the temporal sequence of the actuation of multiple different mechanical elements in a particularly simple and reliable way.
[0021] Moreover, it is preferred to provide the support with one or more guiding elements that are able to modify the position of the at least one mechanical element while moving the carriage relative to the support. The guiding elements can be, for example, a stop for the at least one opening element which, when contacting the stop, cooperates with it in such a way that, for example, it is pivoted about a swivel axis. Alternatively or additionally, the guiding elements can be tapered elements that, for example, can interact with the lever or lever system in order to lock the cassette and accordingly can realize a locking and unlocking of the cassette in a predetermined position in the input device.
[0022] Preferably, a tensioning element, in particular a tension spring, is provided that can pretension the carriage with respect to the support through the movement relative to the support. The tensioning element can hereby, in particular, be formed and/or arranged in such a way that a movement of the carriage in a shifting direction relative to the support generates a restoring force in a direction opposite to the shifting direction. This has the particular advantage that part of the energy used by the operator when inserting the cassette is stored in the tensioning element and is available for an automatic return movement of the carriage bearing the cassette in its interior in a direction opposite to the forward feed direction, in particular after reading out the storage phosphor panel located in the cassette, without an additional return drive being required.
[0023] Moreover, it is preferred that at least one locking element, in particular a locking bolt, is provided that can lock the carriage with respect to the support, in particular automatically. In particular, the locking element and/or the carriage and/or the support are hereby formed in such a way that, when locking the carriage with respect to the support, the carriage can only be moved relative to the support in a shifting direction and not in a direction opposite to the shifting direction. Thanks to this, no further provisions, for example in the form of an unlocking mechanism, have to be made in order to enable a movement of the cassette and the carriage in the shifting direction in which the cassette is inserted in the apparatus by an operator, while at the same time the locking of the carriage prevents a movement in a direction opposite to the shifting direction. In order to release the carriage for shifting it in a direction opposite to the shifting direction, the locking element is preferably coupled to an unlocking mechanism, for example, a manually actuable lever, which, during or after being actuated by an operator, releases the locking element from its locking position.
[0024] Preferably, the input device, in particular together with the carriage and/or the support, is releasably coupled to further components of the apparatus, in particular to a housing in which the read-out device can be accommodated. In particular, a manually actuable unlocking mechanism is hereby provided which is able to unlock the input device, in particular together with the carriage and/or the support, from the apparatus. This allows an operator to remove the input device, optionally together with the cassette, from the apparatus, in particular from the housing, in a simple way if such should be required in case of a failure, for example in case of a failed transfer of the storage phosphor panel to a transport mechanism in order to be transported further to the read-out device, or for maintenance purposes.
[0025] In the system according to a preferred embodiment of the present invention, the cassette preferably comprises a locking element that is able to keep, in particular to lock, the closure, in particular the cover flap, of the cassette in a position which locks the opening, the locking element being actuable from outside the cassette. To that end, an actuating element is preferably provided in the lateral area of the cassette which is mechanically coupled to the locking element and which can be actuated from outside the cassette, for example by an unlocking bolt which can press the actuating element over a finite distance into the cassette.
[0026] The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 a schematic representation of a read-out device for reading out storage phosphor panels.
[0028] FIG. 2 a cross-sectional view of respectively an apparatus and a system comprising an input device.
[0029] FIG. 3 a cross-sectional view of respectively the apparatus and system shown in FIG. 2 with a removed input device and light cover.
[0030] FIG. 4 a lateral view of an input device and a cassette.
[0031] FIG. 5 a top view of the input device shown in FIG. 4 .
[0032] FIG. 6 a lateral view of the input device with an inserted cassette in a first phase of the insertion.
[0033] FIG. 7 a lateral view of the input device with an inserted cassette in a second phase of the insertion.
[0034] FIG. 8 a top view of the input device in the second phase of the insertion shown in FIG. 7 , but without inserted cassette.
[0035] FIG. 9 a lateral view of the input device with an inserted cassette in a third phase of the insertion.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] FIG. 1 shows a read-out device for reading out a storage phosphor panel 1 . A laser 2 generates a stimulating light beam 3 that is deflected by a deflection element 4 in such a way that the stimulating light beam moves along a line 8 across the storage phosphor panel 1 to be read out. The deflection element 4 has a reflecting area, in particular in the form of a mirror, that is made to move oscillatingly by a drive device 5 . Alternatively, the deflection element 4 can have a polygon mirror that is made to move rotationally by a drive device 5 , in this case a motor, and deflects the stimulating light beam 3 across the storage phosphor panel 1 .
[0037] During the movement of the deflected stimulating light beam 3 ′ across the storage phosphor panel 1 , the storage phosphor panel emits emission light depending on the X-ray information stored therein, which emission light is collected by an optical collection device 6 , for example an optical fiber bundle or a suitable mirror device, and detected by an optical detector 7 , preferably a photomultiplier (PMT), and is thereby converted into a corresponding detector signal S.
[0038] The detector signal S is supplied to a device 9 , in which digital image signal values B for individual image pixels of the read out X-ray image are derived.
[0039] The transport of the storage phosphor panel 1 in the transport direction T by a transport device has the effect that individual lines 8 of the storage phosphor panel 1 are successively read out, and a two-dimensional composite X-ray image is thereby obtained that is composed of individual pixels with respectively one associated image signal value B.
[0040] In the example shown, the transport device comprises a roller 10 that is put into rotation about the rotational axis 11 by a roller drive (not shown). The storage phosphor panel 1 is supported with its underside by the roller 10 and is transported in the direction T by the rotation of the roller 10 as a result of the frictional engagement occurring hereby.
[0041] In the displayed example, the roller 10 has magnetic, preferably permanently magnetic or electromagnetic, elements or areas that interact with magnetic or ferromagnetic elements or areas that are provided in the storage phosphor panel 1 , so that the storage phosphor panel 1 is attracted by the roller 10 , which significantly reinforces the frictional engagement and thereby assures a particularly reliable transport of the storage phosphor panel 1 .
[0042] The magnetic elements or areas can be applied to the cylinder-shaped surface of the roller 10 , for example in the form of a coating or a casing of the surface with a magnetic layer or a magnetic band. Preferably, the roller 10 itself is permanently magnetic or ferromagnetic, so that the magnetic layer or the magnetic band, respectively, is already held securely on the roller 10 due to magnetic attraction forces.
[0043] The magnetic elements or areas can, alternatively or in addition, however also be provided in the interior of a roller 10 that is designed as a hollow body, for example by disposing them on a carrier that is located in the interior of the roller 10 . The hollow body of the roller 10 does not have to be magnetic or ferromagnetic in this case, but can also be paramagnetic or diamagnetic. Preferably, this is, in this case, a hollow body made of aluminum.
[0044] FIG. 2 shows a cross-sectional view of respectively an apparatus 12 and a system for reading out storage phosphor panels. The apparatus 12 comprises a housing 13 in which the read-out device shown in FIG. 1 is arranged which is indicated in the selected representation by the roller 10 and the deflected stimulating light beam 3 ′.
[0045] A front area of the housing 13 of the apparatus 12 comprises an input device 20 into which an operator can insert a cassette 40 containing a storage phosphor panel 1 . In the example shown here, the insertion is carried out substantially in a horizontal direction, the cassette 40 being oriented substantially horizontal while being inserted. In principle, however, it is also possible to arrange the input device 20 on another side of the housing 13 , for example on its top side or in a transition area between the top side and the front side, whereby in this case the cassette 40 can be inserted into the input device 20 respectively in a vertical direction or in a direction at an angle to the vertical direction.
[0046] On the interior of the housing 13 of the apparatus 12 , a removal device 14 is provided close to the input device 20 . In the representation as chosen here, the removal device 14 is only represented in a strongly simplified way and is intended for removing the storage phosphor panel 1 being located in the inserted cassette 40 from the cassette 40 and for transporting it in the transport direction T to the roller 10 of the read-out device. A further role of the removal device 14 consists in transporting the storage phosphor panel 1 , after being read out in the read-out device, back into the cassette 40 in the return transport direction which is opposite to the transport direction T.
[0047] The transport and the return transport, respectively, of the storage phosphor panel 1 in the housing 13 occur substantially along a transport path 15 that protrudes beyond the rear area of the housing 13 . For that reason, the rear area of the housing 13 is provided—in the area of the transport path 15 —with a corresponding opening through which the storage phosphor panel 1 can be transported at least partially out of the housing 13 .
[0048] In order to protect the part of the storage phosphor panel 1 which protrudes from the housing 13 of the apparatus 12 from the effect of ambient light and in particular to prevent ambient light from penetrating through the opening provided in this area of the housing 13 into the interior of the apparatus 12 , a light cover 16 is provided that forms a light-tight sealing of the rear end of the transport path 15 . In particular, the light cover 16 prevents ambient light from penetrating into the interior of the housing 13 while the storage phosphor panel 1 is transported and/or read out along the transport path 15 .
[0049] FIG. 3 shows a cross-sectional view of respectively the apparatus 12 and system shown in FIG. 2 with a removed input device 20 and light cover 16 .
[0050] It may be necessary to remove the input device 20 from the housing 13 of the apparatus 12 when, for example, as a result of a failure, the storage phosphor panel 1 contained in the cassette 40 cannot or only partially be removed from the cassette 40 by the removal device 14 or when the removed storage phosphor panel 1 cannot be transferred to the roller 10 . Such a failure is recognized by the control and monitoring electronics of the apparatus 12 and indicated by outputting a corresponding alarm signal, for example in the form of a light signal and/or an audio signal. The operator is thereby informed that a failure, in particular a so-called panel jam, occurs in the front area of the apparatus 12 which can be cleared by removing the removal device 20 . By actuating an unlocking mechanism provided at the housing 13 and/or at the input device 20 , the input device 20 can be released from the housing 13 of the apparatus 12 and then be removed by the operator. The panel jam can then be cleared, for example, by inserting a storage phosphor panel 1 which has been removed only partially from the cassette 40 , as shown in FIG. 3 , fully back into the cassette 40 . After clearing the panel jam, the input device 20 is reconnected to the housing 13 of the apparatus, in particular plugged into it and locked.
[0051] In a further possible failure, the storage phosphor panel 1 is in the area of the rear end of the transport path 15 that is opposite to the input device 20 and cannot be transported any more away from this position by available transport devices, in particular by the roller 10 . This failure too is preferably indicated by a display device provided at the housing 13 of the apparatus 12 or by a corresponding audio signal, whereupon the operator removes the light cover 16 in the area of the rear end of the transport path 15 from the housing 13 , as shown in FIG. 3 . Preferably, the light cover 16 can be coupled to the housing 13 by positive locking and/or frictional engagement. In order to achieve this, preference is given to coupling elements that can be actuated in a simple and quick way, such as, for example, cotter pins, plugs or snap-action mechanisms.
[0052] The apparatus 12 is hereby controlled in such a way that the roller 10 and/or the removal element 14 will no longer be able to transport the storage phosphor panel 1 as long as the light cover 16 is removed. In particular, the storage phosphor panel 1 is not read out anymore as soon as the light cover 16 has been removed from the housing 13 .
[0053] According to a preferred embodiment of the present invention, the input device 20 is formed in such a way that the cassette 40 inserted into the input device 20 by an operator is locked, in particular clamped, and/or opened in the input device 20 , whereby mechanical elements are provided for respectively locking and opening the cassette 40 , the mechanical elements being driven and/or actuated purely mechanically, i.e. by the cassette 40 being loaded into the input device 20 , without additional electrical or electromechanical driving or actuating elements, such as, for example, electrical motors, being required. This is illustrated hereinafter in greater detail in FIGS. 4 to 9 .
[0054] FIG. 4 shows a side view of an input device 20 and a cassette 40 . A face side of the cassette 40 comprises an opening that can be closed by a pivotable flap 41 . In the closed condition shown, the flap 41 is locked by a locking slide (not shown) provided in the cassette 40 so that it cannot open by itself.
[0055] Preferably, the locking slide has the form as described in European patent EP 1 531 359 B1 and comprises an elongate rail with one or more locking openings that, with flap 41 being closed, can be brought into engagement with corresponding raised portions provided on the inside of the flap 41 , thus allowing to lock the flap 41 .
[0056] The respective position of the locking slide relative to the raised portions on the inside of the flap 41 and the associated engaging or non-engaging action in these raised portions are controlled by an externally actuable actuating element 43 which is coupled to the locking slide. Preferably, the locking slide and the raised portions on the inside of the flap 41 are disengaged and hence the flap 41 unlocked by pressing the actuating element 43 from the outside. As soon as the actuating element 43 is again released, it automatically returns to its original position, causing the locking slide to enter again in engagement with the raised portions provided at the flap 41 .
[0057] At each of preferably two narrow sides of the cassette 40 , a notch 42 is provided near the opening of the cassette 40 that allows locking the cassette 40 in a defined position in the input device 20 .
[0058] The input device 20 , which will now be described in greater detail with simultaneous reference to FIGS. 4 and 5 , comprises a carriage 21 that is movably mounted on a support 35 . At the bottom side of the base plate 30 of the carriage 21 , a pin 31 is arranged that is run through a notch provided in the base plate of the support 35 and that is coupled to a pin 32 arranged at the bottom side of the base plate of the support 35 by a tension spring 33 . In case the carriage 21 is shifted in the shifting direction V, the tension spring 33 is loaded, thus generating restoring forces the orientation of which is opposite to the shifting direction V.
[0059] In addition, locking bolts 34 are provided that are run through a perforation in the base plate of the support 35 and that can engage in recesses 29 provided on the base plate 30 of the carriage 21 . The locking bolts 34 are mounted at the bottom side of the base plate of the support 35 using a lever 36 , whereby a pressure spring 37 arranged on the side of the lever 36 that is opposite to the locking bolts 34 ensures that the locking bolts 34 , with the lever 36 not being actuated, are moved in the direction of the carriage 21 , in particular into the recess 29 .
[0060] Preferably, each of the recesses 29 is formed in such a way that the carriage 21 cannot be shifted in a direction opposite to the shifting direction V while the locking bolt 34 engages in the recess 29 . This is preferably achieved by a substantially vertically running flank in the area of the left side of the recess 29 . Alternatively or additionally, the right side of the recess 29 is formed so that, when the carriage 21 is shifted in the shifting direction V, the locking bolt 34 is pressed downward, thus releasing the carriage 21 for being shifted in the shifting direction V. This is preferably achieved by beveling the flank in the area of the right side of the recess 29 , the beveling being inclined in the shifting direction relative to the vertical, preferably by an angle of between 20° and 70°, in particular between 35° and 55°.
[0061] The front side areas of the carriage 21 are provided with a first lever 22 and a second lever 23 whose relative position to the respective side area of the carriage 21 is changeable. Preferably, both levers 22 and 23 are pivotably mounted to the carriage 21 with their end that is leading with respect to the shifting direction V. In principle, however, it is also possible to mount the levers 22 and 23 at the side areas of the carriage 21 in such a way that they can be moved towards and away from the carriage by a linear movement.
[0062] In the example shown, an elongated raised portion 24 and 25 is provided at respectively the first and second lever 22 and 23 , the raised portions being formed and arranged at respectively the first and second lever 22 and 23 in such a way that they can engage in the notches 42 provided at both narrow sides of the cassette 40 when the cassette 40 is inserted up to the stop located in the carriage 21 .
[0063] The first lever 22 is further provided with an unlocking bolt 26 whose form and dimensions and whose arrangement at the first lever 22 is chosen such that, with the cassette 40 in inserted condition, it can actuate, in particular press, the actuating element 43 provided at the narrow side of the cassette 40 .
[0064] Hook-shaped opening elements 27 are furthermore pivotably mounted on the carriage 21 by hinges 28 . The opening elements 27 are formed in such a way that they can engage, with a front end which is formed as a gripper, in the front area of the carriage 21 . A substantially vertically running protrusion 27 ′ is formed at the respective rear end of the opening elements 27 .
[0065] Approximately at the height of the vertically running protrusion 27 ′, a rail-like stop 38 is provided which is part of the support 35 and which is preferably connected to the base plate of the support 35 . Corresponding connecting elements, for example vertically running braces between the stop 38 and the support 35 , have been omitted in the selected representation for the sake of clarity.
[0066] At the support 35 , in particular at the base plate of the support 35 , a first wedge 39 a and a second wedge 39 b are arranged and formed so that they can actuate respectively the first and second lever 22 and 23 while the carriage 21 is being shifted from the position shown in FIGS. 4 and 5 in the shifting direction V.
[0067] FIG. 6 shows a side view of the input device 20 , with the cassette 40 in inserted condition, in a first phase of the insertion. An operator has inserted the cassette 40 in the carriage 21 of the input device 20 until the cassette 40 abuts on a stop (not shown) provided in the area of the front end of the carriage 21 .
[0068] In this position, the notch 42 and the actuating element 43 in the side area of the cassette 40 are positioned at approximately the height of the elongate raised portions 24 and 25 provided at respectively the first lever 22 and second lever 23 (see FIG. 5 ) and of the unlocking bolt 26 . Furthermore, the gripper-like ends of the opening elements 27 engage in recesses provided at the flap 41 of the cassette 40 . Moreover, the above statements in connection with the FIGS. 4 and 5 apply correspondingly.
[0069] FIG. 7 shows a side view of the input device 20 , with the cassette 40 in inserted condition, in a second phase of the insertion in which the operator has inserted the cassette 40 , together with the carriage 21 , so far in the shifting direction V that the locking bolt 34 and the recess 29 provided in the base plate 30 of the carriage 21 have been disengaged by vertically pressing downward the locking bolt 34 from the beveled flank of the recess 29 . The relative movement between the carriage 21 and the support 35 that is triggered by the shifting causes the tension spring 33 to be loaded.
[0070] FIG. 8 shows a top view on the input device 20 in the second insertion phase shown in FIG. 7 in which, however, the inserted cassette has been omitted for the sake of clarity. As can be seen from FIG. 8 , the locking bolts 34 are not engaged in the recesses 29 in the carriage 21 . The shifting of the carriage 21 in the shifting direction V causes the first lever 22 and second lever 23 , that are movably, in particular pivotably, mounted at the carriage 21 , to be moved in the direction towards the cassette 40 (not shown) inserted in the carriage 21 so that the elongate raised portions 24 and 25 engage in the corresponding notches 42 in the side areas of the cassette 40 and thereby lock or fix the cassette 40 in its position relative to the carriage 21 .
[0071] Furthermore, the unlocking bolt 26 provided at the first lever 22 presses on the actuating element 43 located in the side area of the cassette 40 , whereby the actuating element 43 causes the locking slide located in the cassette 40 to release the flap 41 which had been locked by the locking slide, as already illustrated in greater detail in connection with FIG. 4 .
[0072] In the preferred embodiment shown here, the movement of the first and second lever 22 and 23 in the direction of the cassette 40 that is triggered by shifting the cassette 40 together with the carriage 21 is realized by guiding respectively the first and second lever 22 and 23 along a respective wedge surface of respectively the first and second wedge 39 a and 39 b until they are finally maintained in the position shown in FIG. 8 by the surfaces that run parallel to the shifting direction V at the front end of the wedges 39 a and 39 b . Preferably, the levers 22 and 23 are coupled to return springs (not shown) that trigger an automatic return of the levers 22 and 23 when the carriage 21 has returned to an original position shown in FIGS. 4 to 6 .
[0073] FIG. 9 shows a side view of the input device 2 in a third insertion phase in which the operator has shifted the cassette 40 , together with the carriage 21 , further in the shifting direction V, whereby the interaction between the vertical protrusions 27 ′ and the rail-like stop 38 provided at the support 35 causes the opening elements 27 to be tilted around their hinges 28 and thereby engage in corresponding openings in the flap 41 , causing the flap 41 to be opened. The storage phosphor panel 1 contained in the cassette 40 (see FIG. 2 ) can then be removed from the cassette 40 by a corresponding removal element 14 and be transported back into the cassette 40 after being read out.
[0074] In the third phase shown in FIG. 9 , the locking bolt 34 abuts on the rear end of the base plate 30 of the carriage 21 so that the carriage 21 , despite the tension spring 33 being loaded even stronger, cannot automatically move back against the forward feed direction V, but is locked in the position shown in FIG. 9 . The restoring force generated by the tension spring 37 hereby causes the locking bolt 34 to move automatically from the unlocking position shown in FIG. 7 into the locking position shown in FIG. 9 .
[0075] By locking the carriage 21 in the position shown in FIG. 9 , the relative position of the wedges 39 a and 39 b with respect to the levers 22 and 23 and of the rail-like stop 38 with respect to the vertical protrusions 27 ′ of the opening elements 27 is locked at the same time so that the cassette 40 in the phase shown in FIG. 9 stays fixed in the carriage 21 with the flap 41 opened.
[0076] After removing, reading out and returning the storage phosphor panel 1 back into the cassette 40 , the operator can pull the lever 36 vertically upward so that the other end of the lever 36 moves the locking bolt 34 out of its locking position shown in FIG. 9 . The restoring forces generated by the loaded tension spring 33 then automatically move the carriage 21 in a direction opposite to the shifting direction V, whereby the opening elements 27 that are preferably additionally pretensioned by spring elements (not shown) are first moved back from the position shown in FIG. 9 to the position shown in FIG. 7 and thereby close the flap 41 of the cassette 40 .
[0077] As the return movement in the direction opposite to the shifting direction V continues, finally the phase shown in FIG. 6 is reached in which the levers 22 and 23 have again been moved away from the cassette 40 so that the unlocking bolt 26 is decoupled from the actuating element 43 , thus relocking the closed flap 41 by the locking slide located in the cassette 40 . Furthermore, the elongate raised portions 24 and 25 at respectively the levers 22 and 23 are again disengaged from the grooves 42 at the cassette 40 (see also FIG. 5 ) so that the operator can remove the cassette 40 out of the carriage 21 of the input device 20 .
[0078] As demonstrated hereinbefore with reference to FIGS. 4 to 9 , the fixation or locking of the cassette 40 , the unlocking of the flap 41 and its opening in the described input device 20 are exclusively carried out by mechanical devices by using part of the mechanical energy which an operator exerts when inserting the cassette 40 in the input device 20 for directly or indirectly driving mechanical actuating elements in the form of the levers 22 and 23 , including the raised portions 24 and 25 , and the unlocking bolt 26 and the opening element 27 . A further part of the energy applied by the operator is used for loading the tension spring 33 that allows the finished sequence of inserting the cassette 40 to be carried out automatically in the reverse order after the operator has actuated only the lever 36 . This means that virtually no additional force or energy has to be applied by the operator when removing the cassette 40 inserted in the input device 20 from the input device 20 .
[0079] While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
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An apparatus, a corresponding system, and a method for reading out X-ray information stored in a storage phosphor panel includes an input device, into which a cassette with a storage phosphor panel therein can be input, and a read-out device, in which the storage phosphor panel can be irradiated with stimulation light and the emission light excited in the storage phosphor panel is detected. In order to enable the cassette that has been input to be locked and/or opened as reliably as possible in conjunction with a simplified construction, at least one mechanical element which can be mechanically driven by a movement of the cassette upon the cassette being input into the input device locks and/or opens the cassette in the input device
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a self correcting arrangement for self compensation of an operating position servo, such as providing of self compensation whenever the object being controlled by the position servo is being subject to the positioning disturbing external influences, in power-up situations and respectively whenever forceful external influences overpower the positioning operation provided by the servo, respectively when the controlled object exerts a strong inertial load to the servo, which possible conditions in particular are occurring when employing a position servo for turning of a wheel chair seat. The self correcting device described herethrough relates to a positioning servo being of the kind with a servo circuitry comprising elements for handling at least two sets of controlling position signals with each set comprising at least two positioning signals, whereby
a. one of these sets of controlling position signals thus comprises at least two signal components for handling at least 2-dimensional positioning of the movable object which is being controlled through the servo, and whereby
b. another of these sets of controlling signals thus comprises at least two signal components which are for the controlled movable object hereto corresponding, the aimed position of the object, if reached with the aimed velocity of moving, locating and thus of the aimed size of velocity dependent signal components.
2. Description of Related Art
In the case of position servos employed for turning of wheel chair seats, the inertial load presented to the servo is extremely variable, varying from the load presented by an empty seat to the case with a heavy person being seated in the seat, whereto comes that external forces are exerted on the seat while casual driving against hindrances, such as door frames, furniture, walls, beds, etc., or if a helper wants to counterturn the seat to avoid the hitting of neighbouring objects, etc. Also while driving over hindrances on a floor the provision of a device for self correcting or self compensating of the servo in a great many situations must be regarded as advantageous.
Such a self correcting or self compensating device is also advantageous to utilize during power-up of the servo, because the self correcting or self compensating feature makes the providing of a special initial directing of the controlled object unnecessary when powering-up.
In WO 93/20791 belonging to the present applicants, a position servo mechanism for a wheel chair, and in particular wheel chairs with rotary supported seats is described. The described servo mechanism also relates to such a wheel chair seat by which the turning of the seat is activated by activating of a separate turning knob.
SUMMARY OF THE INVENTION
The self correcting device according to the present invention can be employed as an additional unitary device being inserted as a serial element in by way of example the abovementioned servo mechanism of prior art.
On the other hand the self correcting device may also be employed as a unit in servo mechanisms controlling other kinds of objects than just rotary seats.
It is thus, according to the present invention, contemplated that such a self correcting device either remains coupled into the servo circuitry or the device is only coupled into operational condition during the powering-up phase of the servo or it is more or less automatically coupled into the servo circuitry only when an overload condition occurs which could be detected by employing an additional current monitoring stage which monitors the drive current supplied to the drive means for the controlled object and couples the self correcting device into operational condition whenever monitored operational limits indicating overload are exceeded. Such operational limits can furthermore be made able to be selected in size so that conditions for activating the self correcting device can be selected.
An embodiment according to the invention being able to be employed in relation to a turning mechanism for a seat which is held rotary supported in a wheel chair is, by way of example, described in more details as follows under reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically illustrates the principle structure of a position servo being embodied according to the invention and by way of example being arranged for turning a rotary supported seat of a wheel chair, and
FIG. 2 shows further features which may be added to the servo illustrated through FIG. 1.
Elements shown in the drawing which serve the same or serve a corresponding function are indicated through the same sign of reference.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A wheel chair seat S is rotary supported on a seat shaft which is driven through a suitable gear SG from a drive means M which is controlled by a position servo mechanism making the seat capable of being turned 360° an unlimited number of times by turning the rotary supported seat shaft. This seat shaft is, for instance mechanically, connected to an angle encoder encoding the turning angle of the seat, i.e. encoding the position angle θ s of the seat, thereby providing a set of signals to be regarded as, for instance, a set comprising two separate controlling signal components al, a2, whereby the choice of two being in particular the case when the servo is performing a 2-dimensional positioning, as it is the case here when controlling the turning of a wheel chair seat. In the present case, the set of signal components may most simply, by way of example, be made up of two conjugated signals which relationally are represented as, respectively, sin θ s and cos θ s . In practice, the signal components will have to exhibit suitable voltage or current amplitudes corresponding to the individual circuit elements in the circuit employed. For reasons of clarity of explanation, substantially all the various servo signals or signal components comprised within the circuit and to be described using such simple designations as "sin" and "cos" to characterize the signals or the signal components, thus omitting any "local" element dependent amplitudes whenever possible.
By way of example, an embodiment of an angle encoder for the seat angle θ s is shown in FIG. 1. Mechanically, the seat shaft is shown to provide simultaneous rotation through an angle of 180° of two mutually displaced, rotary potentiometer arms. These arms are shown as being comprised within two circularly shaped individual potentiometers which are being supplied with equally polarized DC supply voltages, so that, at any moment, as illustrated schematically with block θ s , two DC-voltages through further sin and cos providing blocks are transformed to exhibit a set of two conjugated signals to be regarded as separate signal components a1 and a2, thus representing the positional turning angle of the seat S through the added synchronous emblematic references sin θ s and cos θ s of these two conjugated signals. These two signals are connected to two multiplying stages MU1 and MU2 and also to two coupling devices c1 and c2 which are described in more details as follows.
To these two multiplying stages MU1 and MU2 are also supplied two other signals b1 and b2 which signals, which are described in further details later, serve to indicate the position which it is the aim to attain with an aimed velocity of rotation of the seat S. The output signals from these two multiplying stages MU1 and MU2 are mutually subtracted, and the resulting signal sin (θ s -θ s ) is connected to a device MPA providing suitable power amplifying and drive power drive means M. The output signal from the device MPA is, for example, connected to the drive means M for turning of the seat S by a drive power monitoring stage IM.
The abovementioned signals b1 and b2 are, for example, referred to, respectively, as sin θ t and cos θ t and also, by way of example, they may be generated as follows.
The seat S of the wheel chair may be activated to rotate by means of a turning knob DS which can be of the kind by which the rotary deflection of the knob DS, being deflectable to one side or the other, determines the size of the turning velocity of the seat. As a safety measure against thereby attaining too large of a turning velocity of the seat, a further selecting key device HS1, HS2 may be provided. By means of this further selecting key device, the maximum turning velocity of the seat which is attainable through maximum deflection of the turning knob DS can be separately selected. It is easily contemplated that other combinations of controlling knobs for the turning of the seat easily can be employed, nevertheless, from an operational point of view, such combinations in operation, in general, can be contemplated in somehow sufficient measure approximately to be thus reducible in structure that they are explainable through the illustrated embodiment.
At the left hand side of FIG. 1, by way of example, switches HS1, HS2 are shown which enable four turning velocities of the seat to be selected, and thus, serve to voltage supply a turning knob potentiometer DS with four selectable supply voltages. The turning knob potentiometer DS is, by means of an unillustrated spring means, mechanically maintained in a mid-position whenever inactivated. When occupying the mid-position, the output signal voltage from the turning knob potentiometer DS is zero, and when deflected for activation to one side or the other, depending on the size of the deflection, a corresponding positive or negative signal voltage θ t is generated. The generated output voltage thus just corresponds effectively to the aimed velocity.
This output signal voltage is, by a circuitry as shown, transformed into two signals which, when the position being aimed at is attained through the course of the aimed size of velocity, indicate the aimed position and are designated as b1="sin" and b2="cos". Thus, these signals, to be regarded as signal components, are valid for the position whenever it is attainable through a course of movement given at the single moments of the course of movement through signal θ t , and which signal thus, with the selected embodiment of it, could exist in shape of a varying signal presented as a compound comprising a sequence of large or small activating deflections, such as are generated by sequentially making (different) turning deflections of the activating turning knob DS.
The circuitry should be easy to understand. Through the reference signs (+) and (-) arranged at the first multiplying stages IM1 and IM2, it is indicated that the single signals have to be connected to either the "+" or the "-" input of the stages. In the illustrated embodiment, it is also the intention that the amplification produced by means of the individual corresponding stages in the course of the paths through the circuitry, causes the respective signals or signal components b1 and b2 to be relatively, at least substantially, of similar size. Through the course of the paths through the circuitry, after the multiplying stages IM1 and IM2, follow change-over stages INIT1 and INIT2, also referred to by c1 and c2, whereby, substituting, a self correcting signal or, what should be the same, a self compensating signal can be coupled into the circuitry as to be described in more details as follows, and then are integrating stages IT1 and IT2 which receive from stages of dividing DI1 and D2, generally as symbolically indicated in the drawing though multiplying, a common signal with such a size that the relative signal value is "1", being acquired as the sum of the square of the sin and cos signals sin 2 θ t og cos 2 θ t received from a square root forming stage Q for this sum signal. The stage Q, thus, is arranged to be in common for the two signal paths existing within the circuitry.
This servo circuitry is going to function in a perfect manner to achieve the purpose, but there exists the danger that either the mutual adaptation between the signals b1, b2 and a1, a2, which may be regarded as signal components during the power-up phase of the servo circuitry, is not good enough, so that the seat S might perform unintentional turning movements during the power-up phase, or that powerful eigen-oscillations may be generated whenever the seat is exposed to any external powerful influencing forces exerted on the seat or during the first power-up of the circuitry, or in the case that the circuit has been energized with an unduly low battery voltage or the like, when operating the wheeled chair and a fresh power-up is being tried under such conditions. On the other hand, experiments with the circuitry has shown that also in case that no unintended eigen-oscillations of the seat S result, then nevertheless, the motor supply current may be unduly augmented leading to a degrading of the performance of the chair, in particular when the drive means M is an electric motor.
According to the invention, a monitoring stage IM is inserted for the purpose to detect strong current increases to such a motor. If the current increases above a certain limit the monitoring stage activates the two change-over stages INIT1 and INIT2 which also are referred to as c1 and c2, so that the two signals a1 and a2 or signal components instead of the signals which arrive from the multiplying stages IM1 and IM2 which receive signal from the turning knob DS, are connected to the inputs on the operating running integrating stages IT1 and IT2 and also simultaneously are further connected to the running integrating stages IT1 and IT2 in such a manner that the output signals from these stages are made equal to the supplied input signals, in particular, for example, the signals d1 and d2, which in the drawing are referred to with the indicated references OUT=IN. In this manner, the output signals b1 and b2 issuing from the two paths through the circuitry are forced to attain such corresponding "sin" and "cos" values that the current of the seat drive means is regulated to zero value. As result of the change-over, the resulting "cos" and "sin" signals present on the inputs (+) and (-) on the multiplying stages IM1 and IM2 in the paths through the circuitry, the current to the motor continues to have a zero value if, after a changing back to again having the multiplying stages IM1 and IM2 operating, which thus is achieved by a changing back of the stages INIT1 and INIT2, also referred to as c1 and c2, the seat turning activating turning knob DS occupies the mid-position, or alternatively, it is safeguarded that the signals or signal components b1 and b2 are brought to running integrated "sin" and "cos" values which correspond in size "correctly" with the size of deflection that the seat turning activating turning knob DS occupies when being deflected away from its mid-position. In case an external mechanical force influence still is exerted on the seat or is brought to influence upon the seat, it is in this manner achieved that in case the motor current again attains too large a size, a self-correcting or self-compensating of the circuitry, as described above, is brought to operate by means of the described change-over facility.
If opposite, under very special circumstances, it should be desired that an extra forceful turning of the seat is to be performed using the drive means M, and in which case, a temporary overloading of the motor is accepted, it is proposed, as an option, that a separately activated, a timing device controlled element could be arranged to temporarily switch off the portion of the servo circuitry which is shown as the monitoring stage IM.
During power-up or when restarting the servo circuitry, the power-up devices, any restarting devices belonging to the circuitry, or some mechanical elements which belong to the servo mechanism, could be arranged to provide a corresponding change-over at the stages INIT1 and INIT2, also referred to as c1 and c2, to take place so that the current to the seat turning drive means M is maintained equal to zero during this particular phase of operation. When the power-up or re-starting procedure is finished, the running integrating stages INIT1 and INIT2, also referred to as cl and c2, again should be arranged to be changed back to be put in operation together with the multiplying stages IM1 and IM2, and then, the seat turning activating turning knob DS is ready to be actively operated.
If it is desired that the seat S be completely free to be turned without any influence from the drive means M, such can be achieved by causing a change-over at the stages INIT1 and INIT2 to take place which produces a coupling condition just as the one produced when the servo circuitry is being powered-up.
A corresponding embodiment is illustrated in FIG. 2 of the drawing. In this embodiment, per se known servo circuit elements IS, K1, K2 and PID are added, i.e. in the form of running integrating stages, of signal amplifying stages providing amplifyings K1 and K2 and of proportional-integrating-differentiating stages all being employed in per se known manner to causing the movements of the seat to take place in a comfortable manner.
The amplifying stage K2 serves to direct supply a contributing signal that is dependent on the velocity signal θ t to the drive means control member MPA, to safeguard that the drive means motor M always, while driving, yields a certain minimum driving power.
A similar corresponding embodiment for providing an adaptation of the velocity to the movement to take place could also be added as a feature to the servo circuitry and thus serving, in the manner as achieved by means of the present servo circuitry, to control the supporting drive wheels of a wheel chair, such as in the case when the wheel chair is supported by several, in particular smaller and equally sized, supporting drive wheels, which wheels, for changing the orientation of driving, all are arranged to be steered equally and simultaneously. As aforementioned, a servo circuitry for such a wheel chair is disclosed in WO 93/20791. In this servo circuitry of the prior art, the steering of the drive wheels also is provided by means of a signal composed of "sin" and "cos" values and by which the size of the signal is made proportional to the desired steering speed. This signal of the prior art circuitry could easily be connected to the left hand side of the first multiplying stages IM1 and IM2, which are illustrated in FIG. 1 and 2 of the present drawing, and instead of these stages which in the drawing are shown connected for the control of a seat turning drive motor M, they would have to be connected to a servo motor of a position servo serving to steer the orientation of the drive wheels. In such case, it is not necessary to arrange such connections, as those described according to the prior art, serving to employ a difference providing stage used to provide the motor steering signal. Subsidiary, another type of easily contemplated connecting-together may be employed being better adapted to serve the steering purpose, such as to employ a multiplying feature with a multiplying factor equal to 2, etc.
According to FIG. 1 of the present drawing a selecting switch device employing four selectable maximum velocities is illustrated. As an alternative, a further steering could be employed, possibly being of a continuous nature, serving simultaneously with DS to determine the maximum velocity, but being made as a function of time, providing a change of velocity per unit of time of the positional signal arriving from the position angle encoder. In this manner, a controlling of the acceleration of the movement is achieved, so that this, when starting the turning, is high, and thereafter, changes so that further velocity changes take place with other rates of acceleration, respectively, deceleration rates being adapted in any equal manner. When a change-over to the operation of the self-correcting or self-compensating feature according to the invention takes place, it is simultaneously achieved that a total "first-beginning" takes place when a turning of the seat is provided by means of the drive means motor which thus is controlled by means of the self-correcting device according to the invention. This solution may be regarded as a very advantageous solution that is able to be achieved by means of the present invention.
It can be added, that one or more elements comprised within the self-correcting device featured according to the invention, in practice, can be provided by means of or be provided through elements which are based on microprocessor technics.
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A device for providing self compensation of an operating position servo, as when external forces influence movement of a movable object, for example, when turning a wheel chair seat, has a position encoder for outputting position signal sets and for turning of the movable object, servo circuitry with elements for simultaneously signal handling at least two sets of controlling position signals, each set having at least two positioning signals. The servo circuitry includes a coupling device having at least two coupling members which are switchable between a first position which passes a respective one of the at least two velocity dependent signal components of the second set of controlling positioning signals to circuitry producing a drive powering signal and a second position at least temporarily substituting a corresponding one of the at least two velocity dependent signal components of the second set of controlling position signals with a respective one of the at least two position signal components of the first set of controlling positioning signals and through this said second position of the coupling members to produce self compensation by at least temporarily producing a self-corrected value of the at least two velocity dependent signal components of the second set of controlling positioning signals, and causing the self-corrected value to be accepted as a new initial drive powering signal which is maintained as the drive powering signal by the servo when the coupling members are switched back and attain said first switching position.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel friction stir welding method and apparatus, as well as a welded structure obtained thereby. Particularly, the invention is concerned with a method and apparatus suitable for joining plural workpieces in a complicated three-dimensional shape.
2. Description of the Prior Art
In Japanese Patent No. 2712838 (WO93/10935) is disclosed a friction stir welding method wherein a metallic rod (hereinafter referred to as “rotating tool”), which is substantially harder than the material of workpieces, is inserted into a joint region of the workpieces and is moved under rotation, and the workpieces are joined together with a frictional heat generated between the rotating tool and the workpieces. This friction stir welding method utilizes a plastic flow phenomenon induced with rotation of the rotating tool in which the workpieces are softened with a frictional heat developed between the workpieces and the rotating tool. It is based on a principle different from a principle of a method (e.g., arc welding) in which workpieces are melted and welded thereby.
As apparatus for practicing the friction stir welding method in question there are known, for example, those disclosed in Japanese Patent Laid-Open Nos. Hei 10-249552 and Hei 10-180467. The apparatus disclosed in Japanese Patent Laid-Open No. Hei 10-249552 is for joining such flat plate-like members as shown in FIGS. 3 and 4, and the apparatus disclosed in Japanese Patent Laid-Open No. Hei 10-180467 is for joining such cylindrical members as shown in FIG. 5 .
These prior art apparatus are the same in that the rotating tool and the workpieces move relatively while maintaining a certain geometrical relation during welding, although both are different in that the workpieces used in the former are such flat plate-like ones as shown in FIGS. 3 and 4, while the workpieces used in the latter are such cylindrical ones having curvature as shown in FIG. 5 . Thus, no special operation is needed during welding if only a geometrical relation between the rotating tool and the workpieces is set beforehand.
However, with a relative movement between the rotating tool and the workpieces, the geometrical relation between the two may change during welding. FIG. 6 shows an example of such a change. As illustrated therein, such a change occurs in the case where a joint line is formed by a combination of a straight line and circular arcs. In this case, it is necessary to take some measure for maintaining the geometrical relation between the rotating tool and the workpieces.
On the other hand, in Japanese Patent Laid-Open No. 2000-135575 is disclosed a structure wherein a rotating tool support member with a rotating tool attached thereto in an inclined state is rotatable about an axis which is perpendicular to the surfaces of workpieces. According to this structure, for joining workpieces in such a form as typified by FIG. 6, it is possible to maintain a geometrical relation between a rotating tool and workpieces.
In a friction stir welding method, a geometrical relation between a rotating tool and workpieces is important in ensuring the soundness of a joint region. More particularly, as shown in FIG. 7, if the rotating tool is tilted at an angle of θ (“attack angle” hereinafter) so that a lower end thereof precedes in a welding direction with respect to the surfaces of the workpieces, it becomes easier to ensure the soundness of the joint region.
A problem found in Japanese Patent Laid-Open No. 2000-135575 is that workpieces can be joined together if they are flat plate-like, i.e., if the surfaces to be joined are flat surfaces, but that arbitrary curved surfaces having a three-dimensional shape cannot be joined.
FIG. 8 is a conceptual diagram of the technique proposed in Japanese Patent Laid-Open No. 2000-135575. In the same figure, a rotating tool 11 is rotated by means of a motor 21 via a rotating tool support member 22 . The rotating tool support member 22 is supported by a rotary cylinder 23 .
FIG. 9 illustrates, in terms of trigonometry, a workpieces joining operation using an apparatus of the configuration shown in FIG. 8, in which workpieces are joined counterclockwise from A to B along a joint line which is rectangular. As welding advances from A to B, the welding direction changes 90°.
At this time, if the welding direction alone is changed in a fixed state of a rotational axis of the rotating tool, the relation between the workpieces and the rotating tool attack angle θ changes into a positional relation which is no longer a proper relation. In this case, if the rotary cylinder 23 is rotated 90°, a rotational axis of the rotating tool support member 22 rotates 90° about an axis perpendicular to the workpieces. Since the rotational axis of the rotating tool support member 22 and that of the rotary cylinder 23 define an angle corresponding to the rotating tool attack angle θ, the relation between the workpieces and the attack angle θ is maintained.
Thus, according to the configuration of the apparatus described above, the rotational axis of the rotating tool, which is tilted at a predetermined certain angle relative to an axis perpendicular to the workpieces, is rotated about the axis perpendicular to the workpieces, thereby making it possible to maintain the relation between the workpieces and the attack angle θ of the rotating tool even when the welding direction changes.
Of importance is that the angle of the axis perpendicular to the workpieces is constant and that the rotational axis of the rotary cylinder 23 is coincident with the axis perpendicular to the workpieces. In other words, according to the configuration of the apparatus described above, the inclination of the rotational axis of the rotary cylinder 23 cannot be altered and therefore it is necessary that the angle of the axis perpendicular to the workpieces be constant. The axis perpendicular to the workpieces indicates a normal line with respect to the surfaces to be joined, or the joint surfaces, and it is only the case where the joint surfaces are flat surfaces that the normal line is constant. If the joint surfaces are arbitrary curved surfaces in a three-dimensional shape, the direction of the normal line is not constant. Thus, according to the foregoing prior art structure it is impossible to join curved surfaces of a three-dimensional shape.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a friction stir welding method and apparatus capable of maintaining a geometrical relation between a rotating tool and workpieces for arbitrary curved surfaces having a three-dimensional shape, as well as a jointed structure obtained thereby.
According to the present invention there is provided a friction stir welding method of joining workpieces by pushing a rotating tool into the workpieces under rotation of the rotating tool and moving the rotating tool along a joint line, characterized in that the workpieces are joined together while setting a posture of the rotating tool to be pushed into the workpieces with use of both a member having the same rotational axis as a rotational axis of the rotating tool and capable of rotating independently of the rotation of the rotating tool and a member capable of deflecting the rotational axis of the rotating tool about an axis which intersects or perpendicularly intersects the rotational axis of the rotating tool.
According to the present invention there is provided a friction stir welding method of joining workpieces by pushing a rotating tool into the workpieces under rotation of the rotating tool and moving the rotating tool along a joint line, characterized in that the rotating tool has two rotational axes capable of rotating independently of the rotation of the rotating tool, one of said rotational axes being the same as a rotational axis of the rotating tool and rotatable in both the rotating direction of the rotating tool and the direction opposite thereto, the other rotational axis being rotatable in a direction intersecting or perpendicularly intersecting said one rotational axis, the workpieces are joined together while setting rotational angles of said two rotational axes with respect to said rotating tool, a normal line direction with respect to joint surfaces of the workpieces and a tangential direction of the joint line are detected, and the rotating tool is moved in three-dimensional directions to join the workpieces while setting, on the basis of the detected normal line direction and tangential direction, an angle of a tip end of the rotating tool with respect to the normal line direction or an angle at which the rotating tool is pushed into the workpieces, as well as a moving direction of the rotating tool with respect to the tangential direction.
According to this method, as is seen from the above, the tip end of the rotating tool can be set to any of all angles and positions in three dimensions, so if a normal line direction of a joint region and a tangential direction of the joint line are calculated from the shape of workpieces, then from the thus-calculated normal line direction and tangential direction it is possible to properly set a normal line direction and a welding direction of the rotational axis at the tip end of the rotating tool.
In a friction stir welding method, as noted earlier, a geometrical relation between the rotating tool and the workpieces is important in ensuring the soundness of the joint region. In a simple joint form such as that wherein joint surfaces of workpieces are flat surfaces and a joint line is a straight line, the soundness of the joint region can be ensured easily by tilting the angle θ (see FIG. 6) so that the lower end of the rotating tool precedes in the welding direction with respect to the surfaces of the workpieces. The angle θ is set with respect to a direction perpendicular to the workpieces. It is preferable that the angle θ be within 10 degrees.
However, in the case of an arbitrary curved surface having a three-dimensional shape, the direction (“normal line direction” hereinafter) perpendicular to joint surfaces and the welding direction vary with place. Having made studies about a method for obtaining a proper geometrical relation for an arbitrary curved surface, the present inventors reaches the conclusion that it is most effective to determine the geometrical relation on the basis of both normal line direction and tangential direction of the joint line (merely “tangential direction” hereinafter).
It is important that both normal line direction and tangential direction be referred to. There are innumerable directions around the normal line which directions each have a certain angle relative to the normal line direction. Therefore, if a tangential direction of the joint line is unknown, it is impossible to determine a specific direction. In a special case where the attack angle is 0°, it suffices to make the rotational axis of the rotating tool coincident with the normal line, but in this case there is a fear that the soundness of the joint region may be deteriorated.
According to the present invention, a coordinate value of a joint line is predetermined from the shape of workpieces, the workpieces are joined together on the basis of the predetermined joint line coordinates, while a positional change of the joint line during welding is detected and a positional relation between the rotating tool and the workpieces is amended successively on the basis of the detected value.
It is also basically possible to joint workpieces while detecting a joint line with use of a sensor. However, in the method of bonding workpieces while successively calculating a normal line direction with respect to joint surfaces and a tangential direction with respect to a joint line on the basis of signals provided from the sensor, the calculation load becomes large. Further, since the workpieces are deformed by pushing of the rotating tool against them, it is possible that a contour different from an initial shape of the workpieces will be detected. Consequently, the coordinates to be referenced to become vague and hence there is a fear that the rotating tool may be pushed in to an excess or conversely it may be pushed in too little.
Studies made by the present inventors have shown that the displacement of workpieces from their initial shape is small and can be corrected by successive amendments during welding.
For the reasons stated above we have found out that it is the simplest welding method to determine a coordinate value (initial value) of a joint line beforehand and then amend the initial value.
Further, according to the present invention, the foregoing problems are solved by detecting a positional change of a joint line during welding at a position which precedes in the advancing direction of the rotating tool. The detection of a positional change of the joint line is basically possible even just after passing of the rotating tool, i.e., even behind the rotating tool in the tool advancing direction, if the detecting position is near the detecting tool. However, in the case where the detection is made behind the rotating tool, the surface roughness of the joint region is large and therefore, particularly in the case of using an optical type of a sensor, the value detected by the sensor may become unstable. Thus, it is effective to detect a positional change of the joint line at a position which precedes in the advancing direction of the rotating tool.
Also, according to the present invention, the foregoing problems are solved by determining a groove portion defined by workpieces or edge portions at ends of workpieces from a sensor output and, on the basis of the groove portion or the edge portions, determining in what amount the position of the rotating tool is to be amended in the joint line width direction.
Most of deformations of workpieces during joining of the workpieces are caused by pushing-in of the rotating tool and therefore the amendment of the rotating tool position is also made mainly in the direction in which the rotating tool is pushed in. However, the joint line position changes also in the width direction of the joint line for each material of workpieces, which is attributable to the difference in dimensional accuracy of to-be-joined members. A large deviation between the joint line and the rotating tool axis in the width direction would result in deteriorated soundness of the joint region. This occurs in butt welding and is marked in the case of a large groove gap. Thus, for ensuring the soundness of the joint region it is important that the joint line and the rotating tool axis be drawn as close as possible to each other in the width direction.
Workpieces are usually chamfered at their edge portions, so even when both are abutted against each other without leaving any clearance, a small gap is present in the abutted region. Even such a small gap can be recognized by a sensor capable of detecting a fine region, such as a laser displacement meter, thus making it possible to establish a criterion for an off-axis condition in the width direction.
On the other hand, in lap welding (FIG. 3 ), it is difficult to directly recognize a joint line because joint surfaces are flat surfaces. However, end edges of workpieces are located away from the joint line, so with the edges as reference, it is possible to specify the position of the joint line.
According to the present invention there is provided a friction stir welding apparatus comprising a rotating tool, a rotating tool drive means which causes the rotating tool to rotate through a transfer member, and a bending drive means which causes the rotating tool to bend through a rotational axis bending member without changing the angle of a rotational axis of the transfer member, and a rotation drive means which causes the rotational axis bending member to rotate through a pivoting member which can rotate independently of the rotation of the rotating tool.
According to the present invention, the foregoing problems are solved by a friction stir welding apparatus wherein a rotating tool is pushed into workpieces under rotation of the rotating tool and is moved along a joint line while it is rotated, to join the workpieces, the friction stir welding apparatus comprising a rotational axis bending member for bending a tip end portion of a rotational axis in an arbitrary amount in a route of a rotating portion from a rotating tool drive unit up to a tip end of the rotating tool, and a pivoting member capable of rotating about a rotational axis in an unbent region from the rotating tool drive unit up to the bending member and capable of stopping at a desired rotational angle.
In the above configuration, the rotational axis bending member functions to tilt the rotational axis of the rotating tool in a normal line direction with respect to joint surfaces or in a direction with an attack angle added to the normal line, while the pivoting member functions to make switching into a tangential direction with respect to the welding direction. Under such functions of the two members, the rotational axis direction of the rotating tool and the workpieces can be kept in proper conditions constantly for arbitrary curved surfaces.
According to the present invention, the foregoing problems are solved by a friction stir welding apparatus comprising a bending drive member which causes a bending quantity to be changed for the rotational axis bending member and a pivoting drive member which causes a pivoting quantity to be changed for the pivoting member. The rotation and pivoting referred to above can be done manually, but in the case of manual operation, a problem arises not only in point of stability, which is low, but also in point of safety. Therefore, the provision of a drive members is preferred in practical use. The use of a drive member is effective in ensuring a high quality of the joint region and also effective in reducing the number of workers because the drive member can be automated in combination with electronic control.
The drive member is not specially limited insofar as it can generate a rotating power. But the use of a motor is most suitable. Above all, a servo motor which can control the amount of rotation with a high accuracy is suitable. Since a rotational speed in bending or pivoting of several revolutions per second suffices, there may be used a small-sized motor in combination with a reduction mechanism having a large reduction ratio.
According to the present invention there is provided a friction stir welding apparatus comprising a rotating tool, a rotating tool drive means which drives the rotating tool through a transfer member, a first arm which supports the transfer member rotatably at one end thereof, a second arm which supports an opposite end of the first arm rotatably at one end thereof, a support base which supports an opposite end of the second arm rotatably, the transfer member and the first arm, the first arm and the second arm, and the second arm and the support base being respectively connected by parallel link means, the rotation of the transfer member, the rotation of the first arm, and the rotation of the second arm being each conducted by operation of a servo motor through a ball screw, and further comprising the foregoing bending drive member, pivoting member and their drive means.
Thus, according to the present invention, the foregoing problems are solved by a friction stir welding apparatus wherein the means for changing the position of the rotating tool comprises arm-like members of a parallel link structure and the operation of each of the arm-like members is performed by means of a ball screw which is rotated with a servo motor.
In friction stir welding, it is necessary to control the push-in quantity of the rotating tool to a value of the order of {fraction (1/10)} mm at the same time when the rotating tool is pushed into workpieces with a force of several hundred to several thousand kilograms (a high-load high-accuracy operation). Welding robots or the like which are currently popular are generally 100 kg or less in terms of a transportable load at a tip end of an arm and are thus not applicable to friction stir welding. Welding robots or the like are generally of a structure wherein a drive motor is mounted directly to a link pin of an arm, and the arm is actuated with the torque of the motor itself. According to this structure, the use of a large-sized motor is needed for increasing the transportable load of the arm. Thus the size of the equipment is increased.
On the other hand, as a structure for realizing a large transportable load, there is known a parallel link structure which is used in construction machines for example. In a construction machine, an arm is actuated with a hydraulic cylinder. With a hydraulic cylinder, however, there is not obtained a satisfactory operation accuracy.
According to the present invention, a high load is realized by adopting a parallel link structure and a high-accuracy operation can be effected by rotating a ball screw with a servo motor, thus permitting both high load and high-accuracy operation to be attained at a time.
According to the present invention there is provided a friction stir welding apparatus comprising a rotating tool, a rotating tool drive means for rotating the rotating tool through a transfer member, a bending drive means which causes the rotating tool to bend through a rotational axis bending member without changing the angle of a rotational axis of the transfer member, a pivoting drive means which causes the rotational axis bending member and the bending drive means to rotate through a pivoting member, the pivoting member having the same rotational axis as a rotational axis of the rotating member and being rotatable independently of the rotation of the rotating tool, a first arm which holds the pivoting member at a fulcrum, a drive means for vertically actuating the fulcrum side of the first arm, a second arm which supports the first arm, a drive means which vertically actuates the first arm side of the second arm, a support base for fixing thereto of the second arm, and a rotary table which supports the support base rotatably on an apparatus base.
Thus, according to the present invention, the foregoing problems are solved by providing a rotational axis bending member and a pivoting member for an arm-like member. With an arm structure, it is possible to attain the reduction of size in comparison with an apparatus constituted by a linear moving axis. By providing a rotational axis bending member and a pivoting member in the arm structure it is possible to afford a friction stir welding apparatus of a more compact structure capable of joining arbitrary curved surfaces.
According to the present invention there is provided a friction stir welding apparatus comprising a rotating tool, a rotating tool drive means which causes the rotating tool to rotate through a transfer member, a bending drive means which causes the rotating tool to bend through a rotational axis bending member without changing the angle of a rotational axis of the transfer member, a pivoting drive means which causes the rotational axis bending member and the bending drive means to rotate through a pivoting member, the pivoting member having the same rotational axis as a rotational axis of the rotating tool and being capable of rotating independently of the rotation of the rotating tool, a drive means which causes the pivoting member to pivot about a fulcrum provided in the pivoting member, a first holding means for holding the pivoting member, a second holding member for holding the first holding member vertically movably, a column which holds the second holding member, a base which holds the column horizontally movably, and a workpiece mount installed on the base and movable horizontally in a direction different 90° from a moving direction of the column.
Thus, according to the present invention, the foregoing problems are solved by a friction stir welding apparatus including three moving means provided on a table with three axes orthogonal to one another as moving axes, and wherein the pivoting member and the rotational axis bending member are movable in association with one of the three moving means. The three moving means cause the tip end of the rotating tool to move to a desired position of workpieces and the pivoting member and the rotational axis bending member function to keep the rotational axis of the rotating tool proper. With the above configuration, therefore, it is possible to join arbitrary curved surfaces.
According to the. present invention, the foregoing problems are solved by using a sensor of the type having a wide measurement range in the width direction of the joint region as a sensor for measuring the distance between workpieces and the rotating tool. As noted previously, for ensuring the soundness of the joint region it is important that the joint line and the axis of the rotating tool be drawn as close as possible in the width direction. The use of a sensor is needed in specifying a joint line position. Various sensors are available, including stylus sensor, spin sensor, and laser displacement meter. For detecting the shape of such a fine region as the recess formed in the abutted region, the spin sensor is unsuitable, while the stylus sensor and the laser displacement meter are suitable. However, even with use of such stylus sensor or laser displacement meter, it is still insufficient to detect the recess in the abutted region. It is necessary that the sensor used be scanned in the width direction of the joint line. There is known a method wherein the sensor itself is reciprocated mechanically. But it is substantially difficult to make an instantaneous measurement in the width direction with advance of welding. Thus, it is most practical to use a sensor of the type having a wide measurement range in the width direction of the joint region.
According to the present invention, the foregoing problems are solved by using an arithmetic unit which calculates a movement quantity of the rotating tool in accordance with the shape of workpieces and a control unit which controls the movement quantity of the rotating tool. For amending the positional relation between workpieces and the rotating tool successively during welding, it is necessary to calculate to what degree the positional relation is to be amended. It is effective and economical to use such an arithmetic unit as typified by a microcomputer which is popular at present. It is also effective and economical to control the thus-calculated amendment quantity by means of a control unit with a microcomputer installed therein.
According to the present invention, by using a rotating tool having two rotational axes rotatably in orthogonal directions different 90° from each other, it is possible to easily set a normal line direction of a joint region and a tangential direction of a joint line from the shape of workpieces, whereby all curved surfaces in three dimensions can be joined. Besides, if those two directions—normal line direction and tangential direction—are detected with use of a sensor, it is possible to determine a rotational axis direction at the tip end of the rotating tool and therefore arbitrary curved surfaces of a three-dimensional shape can be joined while maintaining the rotating tool and the workpieces always in a proper geometrical relation.
Moreover, since the friction stir welding apparatus according to the present invention is provided with a rotational axis bending member for bending a rotational axis in an arbitrary amount in the rotating section from a rotating tool drive unit up to the tip end of the rotating tool and is also provided with a pivoting member which is rotatable about a rotational axis in an unbent region from the rotating tool drive unit up to the bending member and which can stop at a desired rotational angle, even in the case of workpieces having curved surfaces of a three-dimensional shape, the rotating tool and the workpieces can be arranged in an appropriate geometrical relation.
Further, since the means for changing the position of the rotating tool is constituted by an arm-like member of a parallel link structure and the arm-like member is actuated by a ball screw which is rotated by a servo motor, both a large rotating tool push-in load and a highly accurate rotating tool position control can be realized with compact equipment.
Thus, according to the present invention, for arbitrary curved surfaces of a three-dimensional shape it is possible to realize, with compact equipment, a large rotating tool push-in load and a highly accurate rotating tool position control.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an entire configuration diagram of a friction stir welding apparatus according to the present invention.
FIG. 2 is a conceptual diagram showing an entire configuration of a rotating tool assembly used in the present invention.
FIG. 3 is a configuration diagram showing a flat plates butt welding.
FIG. 4 is a configuration diagram showing a flat plates lap welding.
FIG. 5 is a configuration diagram showing welding of cylindrical members.
FIG. 6 is a configuration diagram showing welding of flat plates which is performed along a rectangular joint line.
FIG. 7 is a configuration diagram showing a positional relation between workpieces and a rotating tool.
FIG. 8 is a configuration diagram of a rotating tool used in a conventional apparatus.
FIG. 9 is a configuration diagram showing a positional relation between workpieces and a rotating tool in flat plates welding performed along a rectangular joint line.
FIG. 10 is an entire configuration diagram of a friction stir welding apparatus according to the present invention.
FIG. 11 illustrates the whole of a friction stir welding apparatus as a comparative example.
FIG. 12 is a system block diagram of a friction stir welding apparatus including an arithmetic unit and a control unit.
FIG. 13 is a configuration diagram showing a relation between workpieces and a sensor detection range in butt welding.
FIG. 14 is a configuration diagram showing a relation between workpieces and a sensor detection range in lap welding.
FIG. 15 is a configuration diagram showing a relation between workpieces with projections and a sensor detection range.
DESCRIPTION OF THE PREFERRED EMBODIMENT
First Embodiment
FIG. 1 is an entire block diagram showing an example of a friction stir welding apparatus according to the present invention. The numerals 1 a, 1 b and 1 c denote ball screws, numerals 2 a, 2 b and 2 c denote servo motors, numerals 3 a, 3 b and 3 c denote bearings, numerals 4 a, 4 b and 4 c denote link pins, numerals 5 a and 5 b denote second and first arms, respectively, numeral 6 denotes a main spindle rotating motor, numeral 7 denotes a pivoting member, numeral 8 denotes a bending drive member, numeral 9 denotes a rotational axis bending member, numeral 10 denotes a chucking member, numerals 11 , 11 a and 11 b denote rotating tools, numeral 12 denotes a support base, numeral 13 denotes a rotary table, and numeral 14 denotes an apparatus base.
The second and first arms 5 a, 5 b are pivotable about the link pins 4 a and 4 b, respectively, as fulcrums. The main spindle rotating motor 6 and the rotating tool 11 are mounted to a distal end of the first arm 5 b and can be moved to desired positions by pivotal movements of the second and first arms 5 a, 5 b. The whole of the portion located above the support base 12 is rotated with rotation of the rotary table 13 .
The ball screws 1 a and 1 b are rotated by operation of the servo motors 2 a and 2 b, and with this rotation, the distances between the bearings 3 a, 3 b and the servo motors 2 a, 2 b change, the second arm 5 a moves right and left, and the rotating tool 11 , which is connected to the first arm 5 b through the link pin 4 c, moves vertically.
The ball screw 1 c is rotated by operation of the servo motor 2 c, and with this rotation, the distance between the bearing 3 c and the servo motor 2 c changes, the rotating tool 11 pivots right and left with the link pin 4 c as a fulcrum, and the main spindle rotating motor 6 , pivoting member 7 , rotational axis bending member 9 and bending drive means 8 rotate integrally. The pivoting member 7 can rotate in both right and left directions independently on the same axis as a rotational axis of the rotating tool 11 and is received and fixed into another member with the link pin 4 c as a fulcrum.
FIG. 2 is a perspective view of a rotating tool assembly which causes the rotating tool 11 to bend and rotate. The rotating tool 11 is bent and rotated by the rotational axis bending member 9 . With rotation of the rotating tool 11 through the pivoting member 7 the rotational axis bending member 9 is rotated together with the rotation of the rotating tool 10 by the rotation of the bending drive means 8 in a direction different 90°, i.e., in an orthogonal direction, relative to the aforesaid pivotal rotation.
The rotational axis bending member 9 comprises a bevel gear mounted on a rotating tool-side end of a transfer member 41 which is for the transfer of rotation from the main spindle rotating motor 6 for the rotating tool 11 , a bevel gear which is for the transfer of rotation from the bending drive means 8 , and a bevel gear which transmits a driving force from the bevel gear just mentioned to the rotating tool 11 and which is mounted on rotational axis bending member 9 side of the rotating tool. By means of these bevel gears an angle of insertion of the rotating tool 11 relative to workpieces is changed in all directions. 190° or less is allowable for the rotational angle of the rotational axis bending member 9 as its configuration. The combination of these bevel gears function to effect both rotation of the rotating tool 11 from the main shaft rotating motor and bent rotation of the rotating tool.
The pivoting member 7 is composed of a worm gear for the transfer of driving force from a pivoting drive means 40 and a worm wheel gear for pivoting driving force provided from the worm gear. The pivotal motion causes the rotating tool 11 to rotate while being bent. In this connection, the angle of insertion of the rotating tool 11 is changed by the combination of the bevel gear connected to the main spindle rotating motor 6 , the bevel gear connected to the rotating tool 11 side and the bevel gear connected to the bending drive means 8 side. The rotational axis bending member 9 constituted by such connections of the three bevel gears and the pivoting member 7 are coupled integrally. The combination of these two rotations orthogonal to each other permits any curved surfaces in three dimensions to be joined together in angles and directions which are best suited for the curved surfaces. The total pivoting angle is 370°.
The friction stir welding apparatus of this embodiment, which joins workpieces by pushing the rotating tool 11 into workpieces under rotation of the rotating tool and moving it along a joint line, is provided with the main spindle rotating motor 6 serving as a drive means for rotating the rotating tool 11 , a pivoting drive means which transmits power from the main spindle rotating motor 6 to the rotating tool 11 through the pivoting member 7 and which causes both main spindle rotating motor 6 and rotating tool 11 to pivot about a fulcrum provided in the pivoting member 7 , the bending drive means 8 which causes the rotating tool 11 to rotate through the rotational axis bending means 9 in a direction different 90° from the direction of rotation induced by the pivoting drive means, the first arm 5 b which supports the pivoting member at a fulcrum, a drive means which actuates the fulcrum side of the first arm vertically, the second arm 5 a which supports the first arm 5 b, a drive means which causes the first arm 5 b side of the second arm 5 a to rotate, the support base 12 which fixes the second arm 5 a, and the rotary table 13 which supports the support base 12 rotatably.
As is seen from the above embodiment, the rotating tool 11 has two rotational axes formed rotatably in orthogonal directions different 90° from each other on the basis of both a normal line direction relative to joint surfaces of workpieces and a tangential direction of a joint line. Workpieces can be joined while setting rotational angles of the rotational axes respectively, thus permitting easy welding for three-dimensional curved surfaces.
Second Embodiment
FIG. 10 is an entire configuration diagram showing another example of a friction stir welding apparatus according to the present invention, in which the numeral 28 denotes a column, numeral 27 denotes an apparatus base, and numeral 26 denotes a workpiece mount.
In the same figure, the directions (X, Y, Z) indicated with both-end arrows are moving axis directions, which are orthogonal to one another. A main spindle rotating motor 6 , pivoting member 7 , bending drive member 8 , rotational axis bending member 9 , chucking member 10 , and rotating tool 11 are mounted to a member adapted to move in Z-axis direction. All of these components move with motion of the Z axis.
With a driving force from a servo motor, the pivoting member 7 pivots about an axis parallel to the Z axis though not shown. The total pivoting angle is 370° as is the case with the previous embodiment.
With the bending drive member 8 , the direction of the rotational axis of the rotating tool 11 changes from the portion of the bending drive member 8 so as to rotate in at an angle different 90° relative to the rotation of the pivoting member 7 . The bending operation of the bending drive member 8 is performed using a servo motor through a reduction mechanism (a harmonic drive) of a high. reduction ratio, though not shown. The use of a harmonic drive permits the use of a small-sized motor and hence. permits the reduction in size of the tip end portion extending from the bending drive member 8 up to the rotating tool 11 . The angle of bending by the bending drive member 8 can be set at ±100° with respect to a rotational axis of the main spindle rotating motor 6 .
By allowing the pivoting member 7 to pivot in a bent state of a rotational axis of the rotating tool 11 by means of the bending drive member 8 , the rotating tool 11 can be inserted into workpieces while adding an attack angle in a normal line direction or to a normal line with respect to various portions on arbitrary curved surfaces of the workpieces.
Also in this embodiment there is used the same configuration as in the previous embodiment, whereby the pivoting member 7 can be pivoted in a bent state of the rotational axis of the rotating member 11 by the bending drive member 8 . By a bending angle-pivoting angle combination the rotating tool 11 can be set in a normal line direction for the whole surface of a hemisphere.
The rotating tool 11 is formed using a material substantially harder than the material of workpieces. As the material of the rotating tool 11 there may be used a metal as a typical example. In the present invention there was used a material obtained by heat-treating a tool steel. Ceramics and surface-hardened materials are also employable if only they satisfy requirements for toughness and heat resistance in addition to the required hardness.
In a plane including a joint line and a normal line of workpieces the rotational axis of the rotating tool 11 may be tilted at a predetermined angle (attack angle) backward in the welding direction relative to the normal line. The attack angle is, say, 3° to 10°, of which 3° is adopted in this embodiment.
The friction stir welding apparatus of this embodiment, which joins the workpieces by pushing the rotating tool 11 into the workpieces under rotation of the rotating tool and moving the rotating tool along a joint line, is provided with a pivoting drive means 38 which causes the portion from the main spindle rotating motor 6 up to the tip end of the rotating tool to rotate, the motor 6 serving as a drive means for rotating the rotating tool 11 , the bending drive means 8 which causes the rotating tool 11 to rotate through the rotational axis bending member 9 in a direction different 90° from the direction of rotation induced by the pivoting drive means 38 , a first holding means 38 which holds the rotational axis bending member 9 at a fulcrum, a second holding means 39 which holds the first holding means 38 vertically movably, the column 28 which holds the second holding means 39 , the apparatus base 27 which holds the column 28 horizontally movably, and the workpiece mount 26 which is mounted on the apparatus base 27 and which is movable horizontally in a direction different 90° from the moving direction of the column 28 .
In the apparatus of this embodiment described above, the rotating tool 11 has two rotational axes formed rotatably in directions different 90° from each other on the basis of a normal line direction with respect to joint surfaces of the workpieces and a tangential direction of the joint line, and the workpieces can be joined while setting rotational angles of the rotational axes, whereby a three-dimensional welding can be effected easily.
Third Embodiment
FIG. 12 is a conceptual diagram showing a system configuration of a friction stir welding apparatus according to the present invention, in which the numeral 29 denotes a sensor, numeral 30 denotes the friction stir welding apparatus, numeral 31 denotes a workpiece, numeral 32 denotes an arithmetic unit, and numeral 33 denotes a control unit.
A coordinate value calculated from the shape of workpiece before the start of welding, a normal line direction of a joint region, and a tangential direction of a joint line are inputted as initial values to the control unit 33 .
The friction stir welding apparatus 30 starts welding on the basis of the initial values. At the same time, the sensor 29 detects a positional relation between a rotating tool 11 and the workpieces 31 and inputs the result of the detection to the arithmetic unit 32 . The arithmetic unit 32 collates the detection result with the initial values and inputs amendment values based on a deviation of the two to the control unit 33 . Through these flows the welding proceeds while the initial values are amended in various portions of the joint region.
The arithmetic unit 32 and the control unit 33 are illustrated as separate components in FIG. 12, but in this embodiment both are installed within a single personal computer.
In this embodiment, welding can be performed while allowing a movement path of the rotating tool 11 to be shifted on the basis of a preset joint line and while detecting a relation between the position of a joint line during welding and the position of a tip end of the rotating tool 11 by the sensor 29 and amending the detected value.
Further, welding can be done while detecting the position of a joint line at a preceding position in the advancing direction of the rotating tool 11 by the sensor 29 and while amending the position of the tip end of the rotating tool 11 during welding on the basis of the detected position.
Fourth Embodiment
FIGS. 13 to 15 are conceptual diagrams showing states in which joint regions are measured by a method according to the present invention using the apparatus of the first to the third embodiment. In these figures, the numeral 16 denotes a joint line, numeral 34 denotes a wide angle region measuring type laser displacement meter, numerals 35 , 35 a and 35 b denote edge portions of workpieces, and numeral 36 denotes a measurement region. FIG. 13 illustrates butt welding of flat plates, FIG. 14 illustrates lap welding of flat plates, and FIG. 15 illustrates welding of workpieces formed with projections.
In FIG. 13, laser beam is radiated from the wide angle region measuring type laser displacement meter 34 so that the joint line 16 is located within the measurement region 36 , and the joint line 16 is identified from the measured value. Edges of workpieces 15 a and 15 b are rounded, which is unavoidable in the manufacturing process. When the workpieces are abutted against each other, the round edges define a recess like a groove in the abutted region. In the example shown in FIG. 13, the said recess is identified to identify the joint line 16 .
In FIG. 14, a joint line 16 lies on smooth surfaces of workpieces and therefore it is difficult to directly identify the position of the joint line 16 . However, if a workpiece 17 a is positioned so that an edge portion 35 thereof is within the measurement region 36 of the laser displacement meter 34 , it is possible to identify the position of the edge portion 35 and calculate the joint line on the basis of the edge position.
In the case of such workpieces formed with projections as in FIG. 15, both of the above methods are applicable. One may be selected according to a finished state of workpieces 37 a and 37 b.
In this embodiment the position of a groove formed between workpieces or the position of edge portions at ends of the workpieces is detected and the position of the rotating tool 11 in the width direction of the joint line can be amended on the basis of the detected position of the groove or of the edges.
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A friction stir welding system capable of maintaining a rotating tool and workpieces at a substantially constant geometrical relation for arbitrary curved surfaces having a three-dimensional shape, as well as a welded structure obtained thereby. A method comprises joining workpieces while setting rotational angles of two rotational axes of a rotating tool which the two rotational axes are rotatable in intersecting directions or perpendicularly intersecting directions independently of rotation of the rotating tool, detecting a normal line direction with respect to joint surfaces of the workpieces and a tangential direction of a joint line, and joining the workpieces in three-dimensional directions while setting, on the basis of the detected normal line direction and tangential direction, an angle relative to a normal line direction, as well as a tangential direction, at a tip end of the rotating tool, and also resides in a friction stir welding apparatus using the method.
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CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is related to application Ser. No. 445,778, filed Nov. 30, 1982; application Ser. No. 445,603, filed Nov. 3, 1982; application Ser. No. 445,603, filed Jan. 26, 1983; and application Ser. No. 461,087, filed of even date herewith.
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the batch treatment of materials at low temperature and is particularly concerned with the construction of an insulated chamber for carrying out such treatment, and the insulated access door to such chamber.
BACKGROUND OF THE INVENTION
Various systems are known in the art wherein materials are subjected to treatment within an insulated enclosure at temperatures substantially below those prevailing externally of the enclosure. Among such systems, for example, are included refrigerators and freezers for foods and other perishables as well as insulated chambers wherein articles are chilled to effect embrittlement of associated flash or coatings to facilitate removal of the embrittled portions by high velocity impact with particles of blasting media. To reduce heat leaks from such enclosure and heat transfer through the walls of the enclosure, the walls are thermally insulated and suitable gaskets and other sealing means provided at appropriate places. In installations wherein the temperature differential maintained within the enclosure and the external environment is relatively large, such as a ΔT in the order of 200°-300° F. (=93°-149° C.) or more, there are construction problems associated with the expansion and contraction of structural elements leading, among other untoward effects, to warpage of the chamber walls and the access door thereto. These problems are particularly pressing in relatively large installations, because of the increased dimensional extent of thermal contraction and expansion at a given temperature ranges, and even more so in systems operated in the batch mode wherein the cold chamber is subjected to frequent opening and closing of the access door. This is the case, for example, with systems wherein workpieces, such as coated articles are subjected to cryogenic temperatures within an insulated chamber in a batch operation for embrittlement of the coating to facilitate removal of the coating. Such coating removal will entail a relatively short cycle time of generally less than ten minutes, involving frequent opening of the door between batches while the system is operating at a temperature in the order of about -200° F. (-129° C.). In commercial installations of large size, accordingly, the problems of structural stability despite frequent exposure to changing temperature, are correspondingly aggravated.
Also, in insulated chambers used for low temperature processes, the chamber insulation system needs to be sealed to preclude moisture condensation within the insulation, since such condensation will damage the insulation and render the same ineffective. Commonly, such low temperature insulation systems are protected from moisture condensation therein by lining the interior and exterior surfaces with a metallic material. Such inner metallic liner, of course, will exhibit thermal contraction and expansion as the system cycles from room temperature to cryogenic temperature. Accordingly, the amount of the thermal contraction usually limits this construction technique to relatively small sections, for example less than 60 inches (=152 cm.) in the longest dimension.
It should also be noted in the described prior insulation systems employing outer and inner metallic liners, the outer liner is usually reinforced to provide mechanical strength and stability to the insulated chamber assembly. The inner liner contracts and expands with changes in temperature to which it is alternately exposed, with some buckling and warping thereby resulting. The maximum length of the inner liner and the lowest operating temperature to which it is exposed, determine the total shrinkage of such liner. For example, in a freezer employing liquid nitrogen, wherein the inner liner of the cabinet wall is about 46 inches (=117 cm.) and is exposed to a temperature of about -280° F. (-173° C.), it has been found that there is a shrinkage of about 0.121 inches (0.31 cm.). The extent of buckling and warping of the inner liner under these conditions can be tolerated.
In a freezer employing CO 2 , on the other hand, where the lowest temperature of the operating range is about -90° F. (=-68° C.), an inner liner having a length of 98 inches (=249 cm.) will shrink a maximum of about 0.134 inches (=0.34 cm.), which extent of shrinkage would not effect buckling and warping of the inner liner beyond tolerable limits. However, when the combination of maximum length of the inner liner and the low operating temperature to which the liner is exposed, causes a total shrinkage in excess of the indicated limits, the inner liner will buckle and warp to an extreme degree, causing failure of the inner liner as well as the outer liner. Accordingly, in previous structures having metal panels subjected to extreme changes in temperature, construction was limited in size and temperature variation range to dimensions that will experience a total thermal change in length of no more than about 0.121 to 0.134 inches (=0.31 to 0.34 cm.).
As in the case of the stationary walls the insulated doors of cold chambers are also constructed with metallic outer and inner liners to protect the insulation therebetween from moisture condensation effects. When the metallic edge of the insulated door has a temperature variation from the "cold" face to the "warm" face, the edge of the door will bow. As the amount of the temperature difference increases the extent of distortion, the door will no longer effectively seal, and a gas leak then ensues. The magnitude of the distortion is also proportional to the size of the door; i.e. the length of the door edge. In large conventional insulated doors it is known to incorporate a massive frame external to the insulated door, to resist warpage of the door. Such external frames, besides being very heavy and costly, have only a limited value in controlling warpage of the door.
For efficient operation of systems of the type described, it will be appreciated that it is necessary to maintain a tight seal when the door to the chamber is closed, to prevent influx of warmer air and loss of cold cryogenic gas. To assure the required effective sealing the insulated doors must remain dimensionally stable and withstand the variation in temperatures to which the outer and inner faces of the door are exposed while the door is in its closed position, as well as the immediate change in temperature to which the inner face of the door is exposed between the frequent opening and closing of the door. Any warping or buckling beyond acceptable limits of the door itself and/or of the doorway of the chamber within which the door fits in closed position, will result in poor sealing of the chamber and entail additional expense in the cost of the cryogenic gas needed to maintain desired low temperature operation therein.
Among the several objects of the present invention is to provide a thermally insulated chamber with an insulated access door of novel construction, overcoming the problems heretofore encountered in or presented by prior art structures. A further object is to provide an improved construction adapted for use in large cryogenic chambers having insulated doors, which can be operated efficiently and effectively over a long period of useful life, without suffering excessive warping and deformation at low operating temperatures. A further object is to provide an improved thermally insulated chamber wherein effective hermetic sealing is maintained during operations therein and wherein the insulation within the walls and the door of the chamber is protected against moisture condensation therein.
The foregoing objectives are achieved by the novel construction and arrangement of the present invention.
While not limited thereto, the novel construction of the present invention has its most beneficial advantages in connection with systems employed in removal of flash and coatings by embrittlement and impact. In such systems the workpieces to be decoated, for example, are placed in a thermally insulated chamber wherein they are subjected to a low temperature gaseous atmosphere to effect the desired embrittlement and therein contacted with a high velocity stream of an impact medium such as plastic particles. The cryogenic chamber employed for such decoating operations requires a rigid frame to provide structural integrity for supporting the various mechanical systems in addition to the weight of the chamber itself, which systems include one or more throwing wheels for centrifugally hurling the impact media at high velocity against the workpiece, a plurality of conveyor systems for circulation of the impact media, and mechanically operated means for opening and closing the relatively heavy access door to the treating chamber. The structural framework of the chamber, accordingly, must be sufficiently rigid to maintain the position and alignment of the associated mechanical systems without excessive deflection or vibration.
Decoating operations in particular can be carried out in these cryogenic chambers relatively rapidly, such that in a batch operation the cycle time from one batch to the next needs to be no more than about six to eight minutes. Thus, the outer door to the chamber needs to be opened and closed frequently while the system is at operating temperature, in the order of about -200° F. (=-129° C.).
Examples of various prior art systems for cryogenic deflashing and decoating are described in U.S. Pat. Nos. 2,996,846; 3,110,983; 3,824,739; and Canadian Pat. No. 1,112,048; as well as in the copending U.S. patent applications hereinabove listed.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided a rigid but relatively light skeletal framework for the stationary walls of the insulated chamber, which framework remains at near the ambient temperature prevailing outside the chamber. The outer access door of the chamber comprises a rectangular frame into which a preformed insulated panel is fitted. The door panel comprises an outer rectangular sheet metal liner and several separate adjoined inner sheet metal liners affixed to the outer liner. Each such inner liner is in the form of a rectangular pan having a flat face and a peripheral wall formed by bending up the edges of the liner and then bending each of such bent up opposed edges inwardly towards one another to provide a narrow peripheral lip. The lip so formed provides a flange by which each of the several inner liners is fixedly attached to the outer liner inwardly of the periphery of the outer liner, thus leaving a free peripheral band bordering the assembled door panel. The space between the outer liner and the inner liners of the door panel is filled with suitable insulation material. The assembled insulated door panel is fixedly attached to the rectangular frame of the door by rivets or the like passed through the peripheral band bordering the assembled door panel. The size of each inner liner is limited such that the liner exposed to the lowest temperature prevailing on the inside of the chamber, will shrink to no more than the extent to which buckling can be tolerated without untoward effect on maintaining structure integrity and good sealing of the closed door.
The sidewalls and backwall of the chamber are similarly constructed by provision of a structural skeleton framework and panels attached to the framework of each of said walls. Each of the panels is provided with an inner liner and an outer liner between which liners insulating material is arranged.
While the inner liners of the panel forming the access door as well as those forming the walls of the insulated chamber undergo the full extent of contraction determined by the largest dimension of such liner, this shrinkage is accommodated by the provision of flexible expansion joints in the inner surface and flexible support members through which the linings are attached to the basic framework. The supports and attachments of the inner component are so designed that only paths of low thermal conductance are had.
To minimize the entry of warmer ambient air when the outer door is in open position, a dimensionally stable inner door is provided, in accordance with the preferred embodiment of the invention, which inner door is arranged to swing into position to close off the access space and thus seal the chamber inlet during the period that the outer door is open.
The particular details of the various elements and features of construction in accordance with the invention will be understood and their advantages will be evident from the detailed description below, read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an insulated chamber with the outer door in open position and the inner door shown in phantom;
FIG. 2 is a perspective view of the same chamber as in FIG. 1, taken from another angle, and with the outer door in closed portions; positions being broken away to show internal structure;
FIG. 3 is a view of the chamber door in elevation looking at the inner face thereof, with a portion being broken away to show part of the framework and the outer panel of the door;
FIG. 4 is an enlarged partial view showing details of the attachment between the inner and outer linings of the door and the attachment of the assembled panel to the structural framework;
FIG. 5 is a front elevation of the chamber facing the doorway frame, the door being detached therefrom;
FIG. 6 is a top plan view of the chamber with the outer liner removed, taken from the outside thereof and along line 6--6 of FIG. 5;
FIG. 7 is a bottom plan view of the chamber with the outer liner removed, taken along the line 7--7 of FIG. 5;
FIG. 8 is an elevational view of a side wall of the chamber with the outer liner removed taken at the inside thereof;
FIG. 9 is an enlarged fragmentary view showing details of the attachment of the inner panel of the door to the structural framework of the chamber;
FIG. 10 is an elevational view of the other side wall of the chamber with the outer liner removed, opposite the wall shown in FIG. 8;
FIG. 11 is an elevational view of the rear wall of the chamber with the outer liner removed, taken from the inside thereof;
FIG. 12 is a fragmentary enlarged sectional view of a chamber wall, showing the insulation between the inner and outer liners.
DETAILED DESCRIPTION
The particular embodiment illustrated in the accompanying drawings is one especially designed for decoating of work pieces in batch processes within a chamber maintained at cryogenic temperature, wherein frequent opening and closing of the access door occurs. As seen in FIGS. 1 and 2 the chamber 10 is provided with an outwardly swinging access door 11. Flexible sealing means, such as gasket 12, are provided on the inner face of door 11 approximate to its periphery, designed to fit tightly against the jamb and lintel of frame 13 when the door is in closed position.
Mechanical drive means 14 are supported on a shelf or ledge 15 affixed to the roof of the chamber, for rotating the shaft 16. The upper end of shaft 16 is operatively connected to drive means 14 and the lower end of the shaft is journaled in and supported by a bearing bracket 17 affixed adjacent the bottom of a side wall of the chamber, in line with shelf 15. Hinges 18 and 19 respectively are attached to the outer face of door 11, the free ends of which are affixed to shaft 16, whereby the door can be mechanically opened and closed through rotation of shaft 16 under control of the operator.
The framework of door 11 is made of vertical and horizontal steel channel beams, 21 and 22 respectively, rigidly interconnected at their ends to form a rectangular "picture" frame structure as shown in FIG. 3. Horizontal joists or cross members 23 are fixedly attached at their ends to the upper inner liner 26 and lower inner liner 27 at several levels, to reinforce and stabilize the access door. A sheet metal liner 24 which constitutes the outer face of door 11, is rigidly affixed at its peripheral edges to the channel members 21 and 22 of the frame in the manner indicated in FIG. 4.
Upper and lower inner liners 26 and 27 are each attached to the outer liner 24 to provide an inner space 30 between the outer and inner sheet metal liners for insertion of thermal insulation material in the space provided. Thus, as seen in FIG. 4, liner 27 (as well as liner 26) is doubly bent at right angles 32, 33, at its outer edges in the form of a rectangular C, the short horizontal arm 34 of which faces inwardly, parallel to the width of sheet 27. Stated otherwise, each of the inner liners 26 and 27 is formed into the shape of a rectangular pan having a flat bottom and peripheral side walls, each of said peripheral walls being bent inwardly at its free end to provide a lip or flange 34, by means of which the inner liner can be attached to the outer liner by rivets or the like. The several inner liner pans thus formed are attached to the outer liner 24 inwardly of the periphery of liner 24, thus leaving an outward extending band or border 35 by which the assembled panel is fixedly attached, by rivets or the like, to the channel steel framework such as at 21 and 22. To prevent access of moisture through any of the joints formed at the abutment of flange 34 with the face of liner 24, these joints are sealed by caulking with a bead of RTV silicone rubber or other suitable flexible cement as indicated at 36. A metal plate 37 is attached at the boundary of consecutive inner liners. Thus, as seen in FIGS. 1 and 3, plate 37 is attached to liner 26 along the bottom edge thereof and overlaps the seam at the abutting edges. The lower portion of plate 37 is left free and is adapted to slide vertically over the exposed face of lower liner 27 along the upper edge of that liner; to compensate shrinkage of the panel liners. Space 30 is filled with suitable insulation material; preferably about half the space is occupied by rigid urethane foam adjacent the inner panel 26 and 27, and by fiber glass compressed to fill the remaining space to the outer panel 24.
The rigid framework of the chamber proper is provided by thick metal angle bars welded to one another at their ends to form the structural skeletons of the rectangular side walls, back wall and the front doorway frame of the chamber 10. Additional rigidity, except in the case of the doorway frame 13, is achieved by the provision of additional vertical and horizontal angle members at various locations of the walls. Thus, as seen in FIG. 8, the side wall 40 is formed of vertical beams 50 and 51 and upper and lower horizontal beams 52 and 53. Each of the rectangular frames of opposite side wall 41, back wall 42 as well as doorway frame 13 comprise the same basic rectangular frame structure formed of joined angle steel beams; the pattern of reinforcing beams and interconnecting reinforcing struts of the several walls may vary as required.
Referring again to FIG. 8, side wall 40, on which the two throwing wheels 45 and 46 are to be mounted, includes further reinforcement members to assure structural rigidity. The details of the throwing wheels are described in the related application, Ser. No. 445,778, which description is incorporated herein by reference.
These reinforcement members are provided by horizontal angle bar cross pieces, such as 54, at several spaced intermediate levels along the length of the uprights 50 and 51, vertical struts between the horizontal beams and cross pieces as shown at 57; and additional short cross pieces at selected locations, as shown at 65. The particular arrangement of the reinforcing structure is designed to accommodate particular stress factors associated with each of the individual walls.
The construction of the skeletal framework of the sidewall 41 and backwall 42 are substantially similar and are shown respectively in FIGS. 10 and 11. In each of these structures an additional long upright beam 70 is provided intermediate the vertical beams 71 and 72 of the frame, the beam 70 being joined at its respective ends to the horizontal members of the frame 73 and 74. Further reinforcement for rigidity of the skeleton is had by cross pieces, such as is shown at 75, at several levels intersecting beam 70 and extending at their ends to be fixedly joined to beams 71 and 72.
As shown in FIG. 6, the top of the rigid framework of the chamber proper is reinforced with angle bars 60 and 61. Opening 64 is designed to receive line 67 through which gases in chamber 10 are vented. The bottom of the rigid framework, as shown in FIG. 7, is reinforced with angle bars 62 in a similar manner.
The framework skeletons of the rear wall, each of the side walls, the top and the bottom are covered by a plurality of inner sheet metal liners 76 and an outer sheet metal liner 77; the inner liners and outer liner being spaced apart to provide a space for insertion of insulation material therebetween. As shown in FIG. 12 two such inner liners 76 and 76' are provided in abutting relation. The peripheral edges of the inner liners are bent outwardly at about 90° angles and are continuously welded at the outer ends 82, thereby forming an expansion joint 78 at the seam line between these liners. Rigid polyurethane foam insulation is installed adjacent the inner liners as indicated at 79, the remaining space to the outer liner 77 is filled by compression of fiber glass therein as indicated at 80. The size of the insulation space between the outer and inner liners is maintained by a pattern of retainers, as shown in FIG. 9. Clips 81 formed of sheet steel bent at right angles are provided with one arm welded to the structural angles of the wall frame at selected locations and the other arm welded to the adjacent inner liner. To prevent media particles or other debris from clogging the expansion joint 78, the joint is covered by a flat seal strip 83, one end of which is riveted or bolted to the liner adjacent the seam of joint 78 with the other end of the strip free to ride over the seam.
The outer liner panels are attached to the structural angles by spot welding. All joints in the inner and outer liners are continuously welded except for the corners of chamber 10. These corners are sealed with RTV silicone rubber contained by corner moldings (not shown). Preferably stainless steel is used for the inner and outer liners as well as the structural angles. Additional reinforcement is provided as required, at the inner and outer liners of the chamber and of the outer door, by attachment of steel plate thereto, particularly at locations where mechanical elements are affixed. Thus, in FIG. 8, for example, steel plate is attached to the outer wall spanning struts 57 and struts 54 for mounting of the throwing wheel housings, the plates having openings therein as well as in the outer and inner liners, as indicated at 85, 86, for admission of impact media into the chamber. Similar plate steel reinforcement is provided on the outer and inner panels of door 11 at locations where mechanical accessories are attached thereto.
The illustrated embodiment is designed for an insulated decoating chamber of about 9 feet (2.74 meters) in height and about 5×5 feet (1.52×1.52 meters) in cross section, wherein each of the three walls and the outer door have two inner panels. In a structure of larger dimensions, three or more of such abutting inner liners would be employed. The largest linear dimension, without an expansion joint, of any inner liner of the door and of any wall of the chamber should not exceed that undergoing a shrinkage of 0.22% of such longest dimension at room temperature when exposed to the lowest operating temperature.
Referring again to FIGS. 1 and 2, a cantilever beam 90 extends laterally from the inner face of door 11 near the top thereof, which beam will extend into chamber 10 when the door is in its closed position. Drive mechanism, comprising a motor 91 and speed reduction gearing 92, is mounted on the outer face of the door. The gearing is provided with a horizontal drive shaft 94 passing through a bore in beam 90 and operatively arranged by suitable mechanical means to rotate a work piece-supporting fixture 95, operated within the chamber when door 11 is closed. The particular construction of fixture 95 and the driving means therefor forms no part of the present invention but is the subject of copending application Ser. No. 461,087 filed Jan. 26, 1983.
Extending laterally from the inner face of panel 27, adjacent the bottom thereof is a support arm 96, provided with a slot 97 at its free end. Fixture 95 comprises a suitable shaft 98, the upper end of which is operatively connected for rotation by drive shaft 94 and the lower end of which is slidably supported within slot 97. Thus, any relative movement between panels 26 and 27 as a result of expansion or contraction, is readily accommodated without distortion of shaft 98.
Chamber 10 is also provided with an inner door 100, arranged to swing into closed position when door 11 is opened and to swing back into the chamber to a position adjacent the inner face of a side wall. Inner door 100 comprises a frame made from square aluminum tubing, with an aluminum sheet affixed to one side of the frame.
In its closed position (shown by the dotted outline in FIG. 1) the peripheral edge of door 100 fits tightly against the inner face of the opposed jamb and doorway frame of the chamber. Door 100 is fixedly hinged adjacent top and bottom thereof to a rotatable shaft 101, whereby rotation of the shaft through an arc of about 90° effects corresponding movement of door 100 between its open and closed positions. Rotation of shaft 101 is effected by means of an air cylinder 103 or other suitable operating mechanism, arranged to be actuated in cycle through relays or other interconnecting means communicating with drive means 14, such that door 100 swings to closed position when outer door 11 is opened and returns to open position when door 11 is closed.
Preferably, a guard plate 105 may be affixed to the front face of door 100 to protect the door surface from being bombarded by impact media during decoating or deflashing of articles within chamber 10.
As shown particularly in FIGS. 5 and 7, an opening is provided in the floor of chamber 10 into which opening a chute 106 is fitted and sealed at its outer walls. Chute 106 permits the coating material and spent media to be removed continuously from the chamber. This material empties into 107 for transportation to a separation device (not shown). A preferred arrangement for removing this material from the floor of chamber 10, is that more fully shown and described in copending application Ser. No. 445,603.
While not limited to any particular dimensions of the chamber and structural parts thereof, the invention provides a reliable solution of problems presented by thermal expansion and contraction in structures of a size wherein the extent of warping and buckling of walls or doors would otherwise be prohibitive. Thus, for example, by construction in accordance with the invention, cryogenic treating chambers of about nine feet in height (2.74 meters) can be reliably employed in batch operation for decoating of workpieces at temperatures in the order of -200° F., despite frequent opening and closing of the access door thereto. This is accomplished without resort to massive structural elements. The metallic framework used for both the chamber and the door, although relatively light, provide a structure of required rigidity substantially free of distortion and misalignment. Thermal insulating properties are maintained, although the inner linings will undergo their full thermal contraction, the shrinkage being accommodated by the flexibile expansion joints provided and by the flexible support members which attach the lining to the basic framework. The extent of expansion is limited by resort to the use of two separate and independent panels. The integrity of the insulation is maintained because of the provided protection against access of moisture. Such protection is afforded by the continuous welding of joints in the liners and use of silicone rubber seals at corners where welding is impractical.
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Novel construction is disclosed for a thermally insulated chamber for batch treatment of materials therein at low temperature wherein frequent opening and closing of the outer door of the chamber is practiced. The chamber walls as well as the insulated outer door of the chamber are constructed of rigid but relatively light metallic frames which remain at near ambient temperature. These frames are covered by sheet metal linings on their outer faces and by a plurality of abutting sheet metal inner liners spaced from the outer liners, the space therebetween being filled with insulating material. Buckling and warping of the walls and door as a result of shrinkage is avoided by limiting the maximum linear dimension of each inner liner, by provision of flexible expansion joints in the inner surface and flexible support members which attach the linings to the basic framework, so arranged that paths of only low thermal conductance occur.
The designed chambers are especially useful for removal of coatings on material at cryogenic temperature by contacting the chilled material with a high velocity stream of impact medium. An inner door is provided to close the doorway when the outer door is opened.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to transdermal transport using ultrasound or other skin permeation methods, and, more particularly, to a system and method for continuous non-invasive glucose monitoring.
2. Description of Related Art
The benefits of an intensive glucose management protocol on the mortality of critically ill adult patients is starting to be understood. Dr. James Stephen Krinsley has reported that, in a study recently conducted at the Intensive Care Unit at Stamford Hospital, a protocol that attempts to keep blood glucose levels lower than 140 mg/dL was associated with a significant decrease in motality among critically ill patients. See Krinsley, James Stephen “Effect of Intensive Glucose Management Protocol on the Mortality of Critically III Adult Patients,” Mayo Clin Proc . August 2004; 79(8): 992-1000 (the contents of which are incorporated by reference in their entirety).
Before Dr. Krinsley's protocol was introduced, the standard of care at the ICU, which was typical for most ICUs, was to tolerate moderate levels of hyperglycemia. Thus, insulin was typically not administered unless the blood glucose levels exceeded 200 mg/dL on two successive finger sticks. If the blood glucose level was not above 200 mg/dL, no treatment was provided.
With Krinsley's protocol in place, the glucose levels of patients in the ICU was initially to be measured at least every three hours. To accomplish this, nurses were required to perform a finger stick initially every three hours to obtain a glucose value. If the glucose value exceeded 200 mg/dL on two successive finger sticks, intravenous insulin was administered to the patient. For lower glucose levels, subcutaneous regular insulin was administered. If the glucose value was below 140 mg/dL, no treatment was administered.
Dr. Krinsley's protocol imposed a significant amount of extra work on the nursing staff at the hospital. It required a willingness and commitment on behalf of the nursing staff to take repeated glucose measurements, and by a finger stick.
SUMMARY OF THE INVENTION
According to one embodiment of the present invention, a method for real time remote monitoring and display of a level of at least one analyte in a body fluid of a subject is disclosed. The method includes the steps of (1) contacting a remote device to an area of biological membrane having a permeability level, the remote device comprising a sensor and a transmitter; (2) extracting the at least one analyte through and out of the area of biological membrane and into the sensor; (3) generating an electrical signal representative of a level of the at least one analyte; (4) transmitting the electrical signal to a base device; (5) processing the electrical signal to determine the level of the at least one analyte, and (6) displaying the level of the at least one analyte in real time.
According to another embodiment of the present invention, a system for real time remote monitoring of a level of at least one analyte in a body fluid is disclosed. The system includes a remote device that includes a sensor that generates an electrical signal representative of the concentration of the at least one analyte; and a transmitter that transmits the electrical signal. The system further includes a base device that includes a receiver that receives the electrical signal; a processor that processes the electrical signal; and a display that displays the processed signal in real time.
According to another embodiment of the present invention, a transdermal sensor is disclosed. The transdermal sensor includes a substrate having a first and a second surface. A first electrode trace is formed on the first surface of the substrate. A second electrode trace is formed on the second surface of the substrate. A third electrode trace is formed on the second surface of the substrate. A fourth electrode trace is formed on the second surface of the substrate. A fifth electrode trace is formed on the second surface of the substrate. A dielectric is formed on the second surface of the substrate. A plurality of electrical contacts are provided.
It is a technical advantage of the present invention that a system for continuous non-invasive glucose monitoring is disclosed. It is another technical advantage of the present invention that a method for continuous non-invasive glucose monitoring is disclosed. It is another technical advantage of the present invention that a transdermal sensor is disclosed. It is still another technical advantage of the present invention that a remote device and a base device are disclosed. It is another technical advantage of the present invention that the remote device and the base device may communicate by a wireless protocol, such as a wireless application protocol link, a general packet radio service link, a Bluetooth radio link, an IEEE 802.11-based radio frequency link, a RS-232 serial connection, an IEEE-1394 (Firewire) connection, a fibre channel connection, an infrared (IrDA) port, a small Computer Systems Interface (SCSI) connection, and a Universal Serial Bus (USB) connection.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention, the objects and advantages thereof, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:
FIG. 1 illustrates a block diagram of a system for continuous, noninvasive monitoring of a subject's glucose levels according to one embodiment of the invention;
FIG. 2 illustrates exemplary modules that may be associated with system of FIG. 1 ;
FIG. 3 a is a top perspective view of and FIG. 3 b is a bottom perspective view of a remote device according to one embodiment of the present invention;
FIG. 4 is an illustration of a sensor according to one embodiment of the present invention;
FIG. 5 is an illustration of a transdermal sensor according to one embodiment of the present invention;
FIG. 6 is a detailed schematic for a remote device according to one embodiment of the present invention;
FIG. 7 is an illustration of a state machine executed by controller according to one embodiment of the present invention;
FIG. 8 is a data format in accordance with one embodiment of the present invention is provided;
FIG. 9 is a schematic for a base device according to one embodiment of the invention;
FIG. 10 is an example of a display according to one embodiment of the present invention;
FIG. 11 is an illustration of a method for continuous, noninvasive monitoring of a subject's glucose level according to one embodiment of the present invention; and
FIG. 12 illustrates a method for identifying errors in the transmission of data according to one embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Preferred embodiments of the present invention and their advantages may be understood by referring to FIGS. 1-12 , wherein like reference numerals refer to like elements, and are described in the context of a portable skin permeation system for pretreating an area of skin with ultrasound and then transdermally extracting a continuous flux of glucose to be measured by a sensor.
It is known that ultrasound can be used to increase the permeability of the skin, thereby allowing the extraction of analytes, such as glucose, through the skin. For example, U.S. Pat. No. 6,234,990 to Rowe et al., the disclosure of which is hereby incorporated by reference, discloses methods and devices using a chamber and ultrasound probe to non-invasively extract analyte and deliver drugs (i.e., broadly transdermally transport substances). This provides many advantages, including the ability to create a small puncture or localized erosion of the skin tissue, without a large degree of concomitant pain. The number of pain receptors within the ultrasound application site decreases as the application area decreases. Thus, the application of ultrasound to a very small area will produce less sensation and allow ultrasound and/or its local effects to be administered at higher intensities with little pain or discomfort.
By applying a brief duration of ultrasound, the outer most layer of skin (i.e., stratum corneum) becomes permeable. In an exemplary embodiment of the invention, the area of the pretreated skin site is approximately 0.8 cm 2 . In-vivo studies demonstrate that skin conductivity is significantly enhanced by ultrasound pretreatment and that the enhancement lasts for approximately twenty-four (24) hours. In order to control the ultrasound pretreatment, particularly the duration thereof, the change in skin conductance (or impedance) is measured during the application of ultrasound. When a desired level of skin conductivity is achieved, and hence a desired level of skin permeability, application of ultrasound is terminated. After permeation, passive diffusion or iontophoresis enhances the transport of a drug, such as an anesthetic agent across the treated skin site. In the case of ion ophoresis, a low-level current to a drug delivery electrode and a grounding electrode are employed. The potential difference between the two electrodes allows the drug ions to migrate efficiently from the drug delivery electrode into the skin. The delivery dose is proportional to the level of applied current and the treatment time. Similarly, analytes can be passively or iontophoretically transported across the skin for measurement.
Moreover, U.S. Pat. No. 6,190,315 to Kost et al., the disclosure of which is incorporate by reference, discloses that application of ultrasound is only required once for multiple deliveries or extractions over an extended period of time rather than prior to each extraction or delivery. That is, it has been shown that if ultrasound having a particular frequency and a particular intensity of is applied, multiple analyte extractions or drug deliveries may be performed over an extended period of time. For example, if ultrasound having a frequency of 20 kHz and an intensity of 10 W/cm 2 is applied, the skin retains an increased permeability for a period of up to four hours.
Nevertheless, the amount (e.g., duration, intensity, duty cycle) of ultrasound necessary to achieve this permeability enhancement varies widely. Several factors on the nature of skin must be considered. For example, the type of skin which the substance is to pass through varies from species to species, varies according to age, with the skin of an infant having a greater permeability than that of an older adult, varies according to local composition, thickness and density, varies as a function of injury or exposure to agents such as organic solvents or surfactants, and varies as a function of some diseases such as psoriasis or abrasion.
Once the permeability of the skin is increased, by ultrasound or by another means, the system of the present invention may be implemented. FIG. 1 illustrates a block diagram of a system for continuous, noninvasive monitoring of a subject's glucose levels according to one embodiment of the invention. System 100 generally includes remote device 110 and base device 150 . Remote device 110 , which preferably includes sensor 120 , is provided to a subject and produces a signal (e.g., an amperometric current signal) related to an analyte concentration, such as glucose, in the subject. Remote device 110 may consist of a reusable assembly that produces a signal that represents the magnitude of the current produced by transdermal sensor. Remote device may also produce signals that represent the subject's skin temperature and the charge level of batteries. Remote device 110 also preferably includes transmission unit 130 that transmits the signal to base device 150 . Remote device may also include a unique identifier, such as an identification number.
Base device 150 preferably includes processor 160 that processes the signal to determine the analyte concentration in the subject. Base device 150 preferably also includes display 170 that displays the results for a user.
FIG. 2 illustrates exemplary modules that may be associated with system 100 for carrying out the various functions and features of the embodiments described herein. In some embodiments, the modules may be included that perform the following functions: (1) quantify the current produced by remote device 110 ; (2) measure the subject's skin temperature; (3) measure the voltage level of a battery that may be used to power system 100 ; (4) transmit data among system 100 modules; (5) receive data representing measured values and store them in memory units; (6) receive at least a calibration standard for the subject's glucose level via an input device; (7) predict the subject's glucose level, the glucose level's rate of change, and the percent change in the user's skin temperature; (8) transmit data to base device 130 ; (9) operate the device's alarm functions; and (10) operate the device's error functions. A brief description of each module is provided below. Although the modules are discussed individually by function, it should be understood that a single module may perform more than one function, or, alternatively, that more than one module may be required to perform one function.
Sensor module 205 may monitor the amperometric current produced at remote device 110 and produce a time-stamped measurement of its magnitude. In some embodiments of the system 100 , sensor module 205 may use a potentiostat to measure this current. This value is related to the subject's glucose level.
Temperature module 210 may produce a time-stamped measurement of the subject's skin temperature. In some embodiments of the system 100 , temperature module 210 may use a thermally sensitive resistors (i.e., a thermistor) to measure the temperature. Other mechanisms for measuring the subject's skin temperature may also be used.
Battery module 215 may measure the voltage level of battery or other power source that may be used to power at least some of the modules in system 100 . In some embodiments of system 100 , battery module 215 may use a voltmeter to measure this value.
Relay module 220 may transmit data among at least some of the modules of system 100 using any wired or wireless, digital or analog interface or connection. In some embodiments of system 100 , relay module 220 may use a radio frequency transmitter to transmit data among modules.
Memory module 225 may receive data sent from relay module 220 and store it in memory units. Any suitable type of memory may be used. In one embodiment, a non-volatile memory that can store seven days of data may be used. Other types and sizes of memory may be used as appropriate.
Input module 230 may allow a user to enter data for the system, such as glucose level calibration data. This may be based on a measurement taken from a blood sample. In some embodiments of system 100 , input module 230 may use a keypad to allow a user to input calibration data.
Prediction module 235 may combine calibration data with the signals representing the current in remote device 110 to predict the subject's current glucose level, the glucose level's rate of change, and the percent change of the subject's skin temperature. In some embodiments of system 100 , prediction module 235 may include a microcontroller to predict a subject's glucose levels.
Transmit module 240 may transmit a signal to base device 150 using any wired or wireless, digital or analog interface or connection. In some embodiments of the system, this signal may contain data representing, for example, the current in remote device 110 , the subject's predicted glucose value, the predicted rate of change of the subject's glucose value, the measured current voltage of batteries, the percent change of the subject's skin temperature, etc.
Transmit module 240 may also transmit a signal to a hospitals central patient database.
Alarm module 245 may allow the user to set parameters for the devices' alarm function. These alarms may be set to become active when certain conditions are met, such as when the subject's glucose level reach certain values, when a predicted rate of change reaches a certain value, or when battery voltages reach a certain level. The alarms will be discussed in greater detail, below.
Error module 250 may verify that any data transmitted between system 150 modules is transmitted accurately and securely.
In some embodiments of the invention, modules associated with system 100 may be located independently, with remote device 110 , with base device 150 , or located with both. For example, in system 100 , sensor module 205 , temperature module 210 , battery module 215 , relay module 220 , and transmit module 240 may be colocated with remote device 110 . In this embodiment, the remaining modules of system 100 may be located with base device 150 .
Referring to FIGS. 3 a and 3 b , an exemplary embodiment remote device 110 is provided. FIG. 3 a is a top perspective view of remote device 110 and FIG. 3 b is a bottom perspective view of remote device 110 . Upper portion 310 of remote device 110 includes operational indicator 315 , such as a LED, temperature module 320 , such as a thermistor, battery 325 , and contacts 330 for making contact with contacts 355 on sensor 350 . Upper portion 310 may also include relay module (not shown) and transmit module (not shown).
Lower portion 360 of remote device 110 includes target ring 365 and adhesive 370 .
The upper portion 310 and lower portion 360 of remote device 110 preferably interface so they are easily detachable after use, but are not easily detachable during use. In one embodiment, lower portion 360 is disposable, while upper portion 310 is reuseable.
Although remote device 110 and certain portions thereof are illustrated as being circular, other geometries may be used as necessary.
Referring to FIG. 4 , an illustration of sensor 350 according to one embodiment of the present invention is provided. Sensor 350 includes adhesives 405 and 410 . Adhesives 405 and 410 may be commercially-available medical adhesives. In one embodiment, adhesive 405 may be an adhesive ring MED 3044 with a 9/16 inch inner diameter, and a 1⅜ inch outer diameter, and adhesive 410 may be an adhesive disc MED 3044 with a 1⅜ inch diameter. Both are available from Avery Dennison, 150 North Orange Grove Boulevard, Pasadena, Calif. 91103-3596, USA.
Sensor 350 also includes working electrode 415 , counter electrode 420 , and reference electrode 425 . In one embodiment, working electrode 415 is formed by sputter coating pure platinum (Pt) material, and both counter electrode 420 and reference electrode 425 are formed by screen printing carbon and Ag/AgCl materials.
Referring to FIG. 5 , an illustration of sensor 350 according to one embodiment of the present invention is provided. Electrode 500 may of sensor 350 has an outer diameter of 9/16″. Electrode 500 is mounted on substrate 550 , which is preferably heat annihilated PET. Electrode 500 includes, on a front surface of substrate 550 , silver 505 on a front of substrate 550 , silver/silver chloride 510 , platinum 515 , carbon 520 , and clear dielectric 525 . On a back surface of substrate 550 , silver (not shown) is provided. Connection points to electronics are located on the back of the sensor using a mill-and-fill and printing process by CTI.
Sensor 350 may be provided with a hyrdogel (not shown). In one embodiment, hydrogel may be polyethylene glycol diacrylate (PEG-DA) hydrogel with entrapped glucose oxidase (GOx). Such a hydrogel is disclosed in U.S. patent application Ser. No. 11/275,043, entitled “Biocompatible Chemically Crosslinked Hydrogels For Glucose Sensing,” filed Dec. 2, 2005, the disclosure of which is incorporated reference in its entirety. The hydrogel may be sized to be inserted in the inner diameter of adhesive 405 .
Once sensor 355 is connected and adhered to the subject's skin, it may begin to produce a signal representing an amperometric current proportionate to the subject's glucose level.
Referring to FIG. 6 , a detailed schematic for remote device 110 according to one embodiment of the present invention is provided. Remote device 110 includes switch 610 . Switch 610 may be a contact switch that is triggered when remote device 110 is secured to a subject. For example, transmitter 615 may be electrically disconnected until remote device 110 is secured to a subject.
Remote device 110 also includes battery 620 . In one embodiment, battery 620 is a single 3V Lithium “coin-cell.” It is anticipated that this type of battery will power remote device 110 for a minimum of 1 week. In one embodiment, the voltage of battery 620 is transmitted to and monitored by base device 150 . This voltage may be transmitted at a predetermined time interval, discussed below.
Potentiostat 625 is provided to quantify the amperometric current produced by sensor 350 . In one embodiment, potentiostat 625 sets remote device 110 at a predetermined voltage, such as 500 mV. Once set, sensor 350 will initially start with a high current, such as 50 μA and then ramps down to 200 nA. While at a high current, it is important that potentiostat 625 does not saturate (i.e., the working electrode moves above ground). For this reason, currents above 1 μA will be detected with a low value resistor (kOhms) and currents below 1 μA will be accurately measured with a high value resistor (MOhms).
In one embodiment, potentiostat 625 is bi-polar, splitting the supply voltage in half. For example, potentiostat 625 may split supply voltage 3 V DC into ±1.5 V DC. Because, in one embodiment, the data from potentiostat 625 is downloaded to base device 150 periodically, adequate filtering and roll-off may be provided to average the data over the predetermined time interval.
In addition, signal filtering (not shown) may be provided to reduce spurious noise events, such as current spikes on the order of 5 nA to 10 nA, or greater per minute.
Thermistor 630 is provided to monitor the temperature near the surface of the subject's skin. In one embodiment, this data may be transmitted to base device 150 at a predetermined interval, discussed below.
Analog to digital (A/D) converters 635 are provided to digitize the outputs of potentiostat 625 , thermistor 630 , and the voltage of battery 620 . In one embodiment, this data is collected and stored in memory for transmission to base device 150 . Although three A/D converters 635 are illustrated in FIG. 5 , additional A/D converters may be used, or a single A/D converter with a multiplexed input may also be used.
Controller 640 , which may be a miniature low power controller or state machine is provided to coordinate all hardware interaction. Controller 640 will be discussed in greater detail, below.
Memory 645 is provided to store a unique identifier that is common between the transmitter 615 and base device 150 . In one embodiment, base device 150 may be programmed such that it will only recognize data from a transmitter with a certain unique identifier. Memory 645 may be programmed via programming port 650 .
Programming port 650 is provided to allow firmware and/or a unique identifier to be programmed. Any suitable interface may be used.
Transmitter 615 may be provided to transmit data to base device 150 . Transmitter 615 may communicate via any wired or wireless, digital or analog interface or connection including a Wireless Application Protocol (WAP) link, a General Packet Radio Service (GPRS) link, a Bluetooth radio link, an IEEE 802.11-based radio frequency link, a RS-232 serial connection, an IEEE-1394 (Firewire) connection, a Fibre Channel connection, an infrared (IrDA) port, a Small Computer Systems Interface (SCSI) connection, or a Universal Serial Bus (USB) communication. Other non-protocol based communication methods may also be employed. Transmitter 615 may transmit data to base device 150 at a predetermined interval, such as once every minute. Other intervals may be used as required.
In one embodiment, the same data may be transmitted multiple times during the predetermined interval. For example, if the predetermined time interval is one minute, the same data may be transmitted three times during the predetermined interval. These transmissions may occur at random intervals during the predetermined interval. This provides redundancy to the transmission.
The operation frequency and power are set so that transmitter 615 can communicate with base device 150 . Preferably, the operation frequency and power are in compliance with FCC and FDA requirements.
In one embodiment, prior to transmitting, transmitter 615 checks to ensure that no other transmitter within range are transmitting. This reduces the likelihood of data corruption.
Resistor Rshunt 655 and switch 660 are provided to set the range of the sensor. When switch 660 is closed, the resistance seen is 1 K ohm. This sets the range of the sensor at greater than 1 μA. If switch 660 is opened, the resistance seen is 1 M ohm. This sets the range of the sensor at less than 1 μA.
FIG. 7 is an illustration of a state machine executed by controller 640 . At state 705 , if the power is on, the state machine proceeds to state 710 .
In state 710 , the timer is reset (i.e., the timer is set to zero) and then started. In state 720 , shunt resistor Rshunt is closed. Resistor Rshunt switches in or out a 1 k ohm resistor that is in parallel with the 1 M ohm sense resistor. When resistor Rshunt is open, the measurement resistance is 1 M ohm. Thus, a current of 1 μA is measured as a drop of 1 volt across the resistor. Essentially this provides a very sensitive gain of 1V/1 μA.
When resistor Rshunt is closed, the measurement resistance is 1K ohm in parallel with 1 M ohms, or 999 Ohms (approximately 1 K ohm). The 1 μA now represents a 1 mV drop across the resistor. This reduces the sensitivity to 1 mV/μA.
During sensor conditioning the sensor operates at higher currents therefore the 1 mV/μA gain is used. Once the sensor stabilizes at a lower current, the resistor Rshunt is opened and a gain of 1V/μA is used.
In state 725 , the system waits for a predetermined passage of time, such as a minute. Once that predetermined time is met, in states 730 , 740 , and 745 measurements are made or captured. For example, in step 730 , the current at potentiostat 725 is measured. If the current is less than 1 μAmp, in step 735 , shunt resistor Rshunt is opened.
In state 740 , the voltage at battery 620 is measured, and at state 745 the subject's temperature is measured.
In state 750 , the collected data is formatted for transmission. Any suitable data format may be used. Referring to FIG. 8 , a data format in accordance with one embodiment of the present invention is provided. Data format 800 includes current field 810 , battery voltage field 820 , subject temperature field 830 , device identification number field 840 , minute field 850 , and checksum 860 . Rshunt field (not shown) may be provided to indicate whether Rgain is shunted or not shunted. Additional or fewer fields may be included as necessary and/or desired.
In one embodiment, current field 810 may have a width of 16 bits, battery voltage field 820 may have a width of 7 bits, subject temperature field 830 may have a width of 8 bits, device identification number field 840 may have a width of 16 bits, minute field 850 may have a width of 16 bits, and checksum 860 may have a width of 16 bits.
Referring again to FIG. 7 , in state 755 , the state machine waits to transmit the formatted data. In one embodiment, the state machine waits to ensure that no other devices are transmitting at the same time.
In state 760 , the formatted data is transmitted to base device 150 . Following transmission, the state machine loops back to state 725 .
Referring again to FIG. 1 , base device 150 receives the signal transmitted from remote device 110 . Base device 150 processes the received signal, resulting in a signal that is indicative of the predicted analyte concentration in the subject.
Referring to FIG. 9 , schematics for base device 150 according to one embodiment of the invention are provided. Base device 150 includes receiver 910 that receives the signal transmitted by remote device 110 . In one embodiment as base device 150 receives data from remote device 110 , the data is error checked and written to non-volatile memory 935 . This will be described in greater detail, below.
In one embodiment, base device 150 monitors the operation of remote device 110 . In one embodiment, when base device 150 detects that remote device 110 has been transmitting for a predetermined time, indicating that remote device is attached to a subject, base device 150 prompts the operator to enter calibration data from the blood draw. The calibration data may be a time-stamped measurement of the subject's glucose level taken from a venous blood sample or finger stick meter reading. Preferably, this may take place after one hour of operation. Therefore the blood draw time and date occur between Sensor On+1 hour and the Current Sensor Time.
Programming port 915 is provided in the same manner as programming port 550 .
Interface 920 is provided to allow access to the data stored and/or received by base device 150 . In one embodiment this may be a RS-232 serial connection. Other communications protocols, such as a Wireless Application Protocol (WAP) link, a General Packet Radio Service (GPRS) link, a Bluetooth radio link, an IEEE 802.11-based radio frequency link, an EEE-1394 (Firewire) connection, a Fibre Channel connection, an infrared (IrDA) port, a Small Computer Systems Interface (SCSI) connection, or a Universal Serial Bus (USB) connection may also be used.
Interface 920 may also transmit data to the hospital's patient database and to a patent terminal, central nurse's station, etc.
In one embodiment, seven days worth of data will be stored in a buffer and downloaded via interface 920 .
Clock 925 is provided. In one embodiment, clock 925 is used to time-stamp data that is received from remote device 110 .
Base device 150 is provided with processor 930 . Processor 930 may be either a 16 or 18-series microcontroller. For example, the MicroChip PIC-18 family of processors may be used. In one embodiment, processor 930 preferably includes an internal analog to digital converter (not shown) and program memory (not shown). Processor 930 also preferably includes memory 935 , such as a nonvolatile memory. Memory 935 can be located internal to processor 930 , or it can be located external to processor 930 . In one embodiment, memory 935 should be of adequate size to hold a minimum of 24 hours worth of data.
Processor 930 executes software, firmware, and/or microcode. This will be discussed in greater detail, below.
Memory 935 may store a unique identification code in the same manner as memory 645 .
Base device 150 includes a power supply, such as battery pack 940 . In one embodiment, battery pack 940 supplies base device 150 with power for 1 week without replacement. In one embodiment, battery pack 940 may be a rechargeable battery pack.
During operation, battery voltage may be monitored. This may require an analog to digital converter (not shown). If the voltage of battery pack 940 falls below a predetermined voltage, the operator is alerted. This may include a visual indication, or an audible indication. Preferably, powering-down base device 150 , or replacing battery pack 940 does not result in any data being lost.
Alarm 950 and mute switch 955 are provided. In one embodiment, alarm 950 is a piezoelectric alarm that is used to alert the operator of certain events, alarm states and error conditions. These, as well as other types of alarms and notifications will be discussed in greater detail below.
In one embodiment, mute switch 955 is provided to mute or silence alarm 950 .
Base device 150 may include an input device, such as keypad 960 . Keypad 960 may include several input switches, such as nine poly dome-type switches, that are used to input data and control remote device 110 and/or base device 150 in another embodiment a touch-screen may be used.
Base device 150 also includes display 965 . In one embodiment, display 965 is a liquid crystal display. The operating characteristics of display 965 may be configured (e, contrast, viewing angle, backlight, etc.) as necessary.
Display 965 may graphically present information to a user in real time. For example, in one embodiment of the invention a subject's glucose level may be graphically displayed for a certain period of time. Notable events, such as actual blood measurements, injections of insulin, etc. may be graphically displayed on the timeline so that the impact of such on the subject's glucose level may be viewed.
Other parameters, such as the subject's glucose rate of change, temperature, and temperature rate of change, may also be graphically displayed. In addition to display 965 , base device 150 may also include LEDs (not shown) as necessary to provide status information (e.g., power on/off, battery status, etc.) to the user.
Referring to FIG. 10 , an example of a display according to one embodiment of the present invention is provided. Display 1000 includes graphical representation 1010 of blood glucose versus time. In one embodiment, graphical plot 1010 for the past four hours is displayed; other time periods may be displayed as desired. In another embodiment, the scales may be selected by a user.
Marker 1020 may be provided to indicate when insulin was administered to the subject. In one embodiment, marker 1020 may comprise a vertical line, such as that shown in FIG. 10 , Label 1030 may also be provided to indicate what marker 1020 is marking. In another embodiment, marker 1020 may be selected by a user such that it most effectively indicates the time at which the insulin was administered
Marker 1020 may also provide additional information, such as the doseage of the insulin, the person who administered the insulin, and the time of that the administration occurred. This may be continuously provided in display 1000 , or it may be provided in a drop-down box (not shown) that is selected by a user.
FIG. 11 illustrates a method 1100 for continuous, noninvasive monitoring of a subject's glucose level, preferably in an intensive care unit, according to one embodiment of the invention. In some embodiments, method 1100 may be performed by system 100 of FIG. 1 .
In step 1105 , the permeability of an area of a subject's skin is increased. This may be accomplished by any suitable mechanism, including the application of ultrasound, mechanical disruption, laser skin ablation, electroporation, RF ablation, microneedles, chemical peel, etc. In one embodiment, the SonoPrep® Skin Permeation Device, available from Sontra Medical Corp., Franklin, Mass., may be used to increase the permeability of the area of skin. Other devices, such as the QuickPrep™ automated patient prep system available from Quinton, Inc., 303 Monte Villa Parkway, Bothell, Wash. 98021-8906, may also be used.
In step 1110 , the remote device is positioned and affixed to the area of skin. Preferably, remote device is affixed to the area of skin by a medical grade adhesive. Remote device should be securely affixed so that it is not unintentionally removed from the area of skin, but not preferably does not cause significant skin damage when removed.
A medium may be provided between the surface of the skin and the sensor in order to keep the two in aqueous contact. In one embodiment, a hydrogel disc may be positioned between the skin and the sensor. Referring to FIG. 4 , the hydrogel disc is preferably inserted in the interior portion of adhesive ring 405 .
Referring again to FIG. 11 , in step 1115 , once the remote device is affixed, the sensor begins to produce a signal, such as an amperometric current, that is representative of a subject's glucose level. In step 1120 , the magnitude of the signal is measured, and may associated with the current time (i time-stamped). Additionally, other modules, such as the temperature module and the battery module, may measure the subject's skin temperature and the voltage level of the a battery, respectively. These measurements may also be time-stamped.
In step 1125 , the time-stamped measurements may be transmitted from the remote device to the base device. As discussed above, this transmission may be made by any suitable wired or wireless protocol. Prior to transmission, a unique identification number and checksum value may be added to this data in order to produce a secure and accurate transmission.
In step 1130 , the base device receives the transmitted data and stores it in memory. In one embodiment, the base device may verify the integrity of this transmitted data. This may be accomplished through the use of a checksum value. In addition, the identification number may be compared to one that is stored in the base device's memory.
At step 1135 , the user may input at least a glucose calibration standard for the subject. This calibration standard may be a time-stamped measurement of the subject's glucose level taken from a venous blood sample or finger stick meter reading. The user may input this calibration standard through the use of a keypad or other input device attached to the base device.
At step 1140 , the base device may combine the time-stamped data representing the current produced by the remote device and the inputted calibration standard to predict the value of the subject's glucose level. The base device may calculate the predicted glucose value, current, and percent change in skin temperature by using the following equations:
Predicted Glucose t =I t ×(Measured Glucose t=cal /I t=cal );
I t =sensor current−baseline; and
Displayed Temp t =(Temp t /Temp t=cal )×100
where baseline is a preprogrammed value in nA.
Predicted Glucose Rate of change=Predicted Glucose T −Predicted Glucose T=1
Predicted glucose displayed may also be adjusted to compensate for temperature changes and temporal changes. This is discussed in greater detail in U.S. patent application Ser. No. 10/974,963, entitled “System and Method for Analyte Sampling and Analysis,” the disclosure of which is incorporated by reference in its entirety.
In some embodiments of the method, these calculations may be performed by the prediction module using a microcontroller.
At step 1145 , the base device displays this data, including data representing the current in the remote device; the subject's predicted glucose value; the predicted rate of change of the subject's glucose value and a future estimated glucose value (T+10 minutes, for example) based on the rate of change; the voltage of the batteries in either remote device, base device, or both; the percent change of the subject's skin temperature; and the status of the piezo alarm. The number of minutes that have elapsed since the remote device was first attached to the subject may also be displayed.
In one embodiment, the results may be displayed graphically, as discussed above with reference to FIG. 10 .
As discussed above, the method and device of the present invention included an alarm function that provides an audible and/or visual notification when predetermined conditions are met. In one embodiment, the following alarms may be provided: (1) hypoglycemic; (2) hypoglycemic anticipated; (3) hyperglycemic; (4) hyperglycemic anticipated; (5) low remote device battery; (6) low base device battery; (7) communication link lost; (8) communication link disturbed; (9) bad sensor data; (10) 1 hour left; and (11) 24 hours exceeded. Other alarms may be provided as necessary and desired.
These messages may also be transmitted to and displayed on a patient terminal via a central database, and/or displayed at a central nurse's station.
In general, a single measurement that meets a predetermined condition is insufficient to trigger an alarm. Rather, two (or more) consecutive alarm conditions are required to trigger the alarm. The number of consecutive alarm conditions may be increased or decreased as necessary and/or desired.
Each of these alarms will be discussed in greater detail below. Although a variety of conditions precedent for each alarm may be used, a set of preferred conditions will be discussed.
The hypoglycemic alarm may be triggered when two consecutive glucose predictions are below a preset limit. In one embodiment, the preset limit may be 60 mg/dl. In addition, the preset limit may vary from subject to subject.
The hypoglycemic anticipated alarm may be triggered when five minute averaged rate of change predicts that two consecutive glucose readings will be below the hypoglycemic preset limit within ten minutes.
The hyperglycemic alarm may be triggered when two consecutive glucose predictions are above a preset limit. In one embodiment, the preset limit may be 200 mg/dl. In one embodiment, the preset limit may be 160 mg/dl. In addition, as with the preset limit for the hypoglycemic alarm, the preset limit may vary from subject to subject.
The hyperglycemic anticipated alarm may be triggered when five minute averaged rate of change predicts that two consecutive glucose readings will be above the hyperglycemic preset limit within ten minutes.
The low remote device battery and low base device battery alarms may be triggered when the measured voltage on either battery falls below a predetermined voltage. In one embodiment, the predetermined voltage may be set in order to provide at least a certain amount of time before the battery fails. For example, when the battery voltage for the remote device falls below 2.8 VDC for two consecutive transmissions, or when the battery voltage for the remote device falls below 6.0 VDC, the respective alarms are triggered.
Power-saving techniques, such as a reduction in power to the display, may be employed to conserve power once the alarm condition is met.
The communication link lost alarm may be triggered when two consecutive measurements are missed.
The communication link disturbed alarm may be triggered when two consecutive data streams with valid identification code have invalid check sum values.
The bad remote device data alarm may be triggered when two consecutive data streams have sensor currents below a predetermined value, such as 10 nA (any time) or above a predetermined value, such as 1 uA, after a certain period of operation, such as 35 minutes.
The 1 hour left alarm may be triggered when two consecutive data streams report times greater than 1380 minutes (i.e., 23 hours).
The 24 hours exceeded alarm may be triggered when two consecutive data streams report times greater than 1440 minutes (i.e., 24 hours)
The alarms may be displayed until the mute switch is pressed. In the case of multiple alarms, the base device may queue the alarms in a first in first out sequence. Each time the mute switch is pressed, the current alarm will be cleared and the next alarm in the queue will be displayed. In one embodiment, certain alarms, such as hypoglycemic and hyperglycemic will have priority over all other alarms and be displayed regardless of their position in the queue.
FIG. 12 illustrates a method for identifying errors in the transmission of data. In step 1205 , data may be transmitted wirelessly between the remote device and the base device of the system. As discussed above, in some embodiments, this data may contain a measurement of the current produced at remote device, a measurement of the subject's skin temperature, and a measurement of the transmitter unit's battery. This data may also have been formatted to include a timestamp value, checksum value, and a ID number.
In step 1210 , the security and accuracy of this transmitted data may be verified. In one embodiment of the method, an error module may use a microprocessor to compare the timestamp of the most recent data transmission to that of previous transmissions, to compare the data identification f the most recent data transmission to that which is stored in the base device's memory, to verify the transmitted data's checksum value, and to analyze the value of the current produced in the remote device.
In step 1215 , the system may notify the user if the data is found to be insecure or inaccurate. In one embodiment of the method, the error module may sound an alarm if (1) a comparison of the data timestamps shows that two consecutive transmissions have been missed (2) two consecutive data transmissions have incorrect checksum values (3) a predetermined number of measurements for the current in remote device are below or above certain preset values. In one embodiment, it two measurements are below or above the preset values, the alarm is activated.
in one embodiment, system 100 may interface with a mechanism for providing insulin. Thus, with this addition, not only is the hypoglycemic or hypoglycemic conditions detected and/or predicted, but the conditions are appropriately treated automatically. In one embodiment, the initiation of treatment requires human authorization, the insulin cannot be administered without a human authorizing the administration. In other embodiments, human authorization is only required for the administration of insulin in extreme conditions.
The present invention contemplates a system that continuously monitors the amount of insulin treatment and the effect of that insulin treatment on the subject's glucose level. Because the effect of insulin on a glucose level will vary from subject to subject, and even within the same subject, the system may attempt to determine an optimum insulin treatment based on past performance. However, until several insulin treatments are observed, it may be difficult for the contemplated system to accurately determine the amount of an insulin treatment required. Therefore, until a sufficient number of observations have been completed, the system may require all insulin to be administered by a human.
The various embodiments of the systems and methods described and claimed herein provide numerous advantages. For example, the systems and methods permit continuous, noninvasive detection of a subject's glucose levels. Thus, a user can monitor the a subject's post operative glucose levels more frequently, effectively, and comfortably. Such improved systems and methods for monitoring post operative glucose levels may help to reduce a subject's risk of infection and reduce hospitalization.
Other embodiments, uses, and advantages of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. The specification and examples should be considered exemplary only.
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A system and method for continuous non-invasive glucose monitoring is disclosed. According to one embodiment of the present invention, the method includes the steps of (1) contacting a remote device to an area of biological membrane having a permeability level, the remote device comprising a sensor and a transmitter; (2) extracting the at least one analyte through and out of the area of biological membrane and into the sensor; (3) generating an electrical signal representative of a level of the at least one analyte; (4) transmitting the electrical signal to a base device; (5) processing the electrical signal to determine the level of the at least one analyte; and (6) displaying the level of the at least one analyte in real time. The system includes a remote device that includes a sensor that generates an electrical signal representative of the concentration of the at least one analyte; and a transmitter that transmits the electrical signal. The system further includes a base device that includes a receiver that receives the electrical signal; a processor that processes the electrical signal; and a display that displays the processed signal in real time.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for charging a secondary battery.
2. Description of the Related Art
Methods for charging a secondary battery can be generally classified into constant-voltage methods and constant-current methods. The constant-current method is capable of rapid charging but is likely to result in overcharging. The constant-voltage method generally controls the charge voltage at a level which is equal to or less than a voltage which causes hydrogen gas generation within the secondary battery. As a result, the charge current decreases as the charging process proceeds, thereby minimizing overcharging.
Thus, the constant-voltage method minimizes overcharging but may result in undercharging. Therefore, methods have been used which combine both the constant-voltage method and the constant-current method.
In the case of combining both the constant-voltage method and the constant-current method, the control voltage, current, and charge time are prescribed so that the proper charge electricity amount equals about 105% to about 120% of the discharged electricity amount.
In recent years, lead-based secondary batteries have replaced conventional liquid-type lead secondary batteries as power sources for various cycle services such as electric automobiles. In particular, lead secondary batteries of a sealed type, which absorb gaseous oxygen generated within the batteries at the negative plates by employing a limited amount of electrolytic solution, have been in use.
Sealed-type lead secondary batteries for cycle services may be subjected to various loads depending on the specific device for which they are used, and various usage time and/or frequency depending on the user. Therefore, the degree of discharge or “discharge depth” which is experienced by sealed-type lead secondary batteries may vary from battery to battery.
It has been discovered that, in the case of aforementioned sealed-type lead secondary batteries for cycle services, merely prescribing a certain charge electricity amount relative to the discharged electricity amount does not allow the sealed-type lead secondary batteries to exhibit desired longevity characteristics.
For example, it to conceivable that a sealed-type lead secondary battery which has not been well-discharged (i.e., “shallowly discharged”) may be charged by using a charger which is intended for a well-discharged (i.e., “deeply discharged”) sealed-type lead secondary battery. Such a charger has a relatively high charge voltage. In such cases, the lifetime of the sealed-type lead secondary battery may be drastically shortened even is a ratio of discharged electricity amount to charge electricity amount within a conventionally acceptable range is prescribed. The problem of such shortened lifetimes becomes especially conspicuous with sealed-type lead secondary batteries employing a Pb—Ca—Sn type alloy (not containing any Sb) as a positive grid alloy and employing a limited amount of electrolytic solution.
Moreover, the above-mentioned problem may unpredictably occur or may not occur at all, depending on the manner in which a given device associated with such a sealed-type lead secondary battery is used by a user. It is practically impossible to select different types of chargers depending on the manner in which a device associated with such a sealed-type lead secondary battery in used by a user.
SUMMARY OF THE INVENTION
A method for charging a secondary battery according to the present invention includes: a first step of precharging the secondary battery; a second step of measuring a first secondary battery voltage Vba 1 after performing the precharging; and a third step of charging the secondary battery based on the measurement of the first secondary battery voltage Vba 1 .
In one embodiment of the invention, the first step includes a fourth step of measuring a second secondary battery voltage Vba 0 prior to the charging of the secondary battery, and the third step includes: a fifth step of comparing the first secondary battery voltage Vba 1 against a first prescribed voltage V 1 , a second prescribed voltage V 2 , and a third prescribed voltage V 3 , where V 3 <V 2 <V 1 ; a sixth step of performing a first charging in a first charge mode if the first secondary battery voltage Vba 1 is between and including the first prescribed voltage V 1 and the second prescribed voltage V 2 ; a seventh step of performing a second charging in a second charge mode if the first secondary battery voltage Vba 1 is between and including the second prescribed voltage V 2 and the third prescribed voltage V 3 ; and an eighth step of performing an active charging if the first secondary battery voltage Vba 1 is lower than the third prescribed voltage V 3 .
In another embodiment of the invention, the eighth step includes: a ninth step of repeating a cycle including the active charging and an ensuing measurement of a third secondary battery voltage Vba 2 , within a predetermined cycle limit, until the third secondary battery voltage Vba 2 becomes higher than the third prescribed voltage V 3 , and performing a second charging in the second charge mode if the third secondary battery voltage Vba 2 becomes higher than the third prescribed voltage V 3 within the predetermined cycle limit; and a tenth step of terminating the charging for the secondary battery if the third secondary battery voltage Vba 2 has not become higher than the third prescribed voltage V 3 within the predetermined cycle limit.
In still another embodiment of the invention, the sixth step includes: a step of subjecting the secondary battery to a constant-voltage charge using a first charge voltage Vch 1 and a step of subjecting the secondary battery to a constant-voltage charge using a second charge voltage Vch 2 after a charge current has decreased to a predetermined value Ia, where Vch 2 <Vch 1 . The seventh step includes: a step of subjecting the secondary battery to a constant-voltage charge using a third charge voltage Vch 3 ; an eleventh stop of subjecting the secondary battery to a constant-current charge using a predetermined charge current Ic after the charge current has decreased to a predetermined value Ib, and a step of subjecting the secondary battery to a constant-voltage charge using a charge voltage Vch 4 after the eleventh stop, where Vch 4 <Vch 3 .
In still another embodiment of the invention, the method further includes: a step of terminating the charging for the secondary battery if the first secondary battery voltage Vba 1 measured after performing the precharging is higher than the first prescribed voltage V 1 or if the first secondary battery voltage Vba 1 is lower than a fourth prescribed voltage V 4 , where V 4 <V 3 .
In still another embodiment of the invention, the first stop includes: a step performed in a case where the second secondary battery voltage Vba 0 is equal to or greater than a fifth prescribed voltage V 5 , the stop including: measuring the first secondary battery voltage Vba 1 after the precharging is measured if a charge current Ip during the precharging to equal to or smaller than Imax and equal to or greater than Imin (where Imin>0): displaying a warning message to indicate abnormal operation of a charging device and terminating the charging if the charge current Ip is greater than Imax; or displaying a warning message to indicate abnormality of the secondary battery and terminating the charging if the charge current Ip during the precharging is smaller than Imin; and a step performed in a case where the second secondary battery voltage Vba 0 is lower than the fifth prescribed voltage V 5 , the step including: displaying a warning message to indicate abnormal operation of the charging device and terminating the charging if the charge current Ip to greater than Imax; and measuring the first secondary battery voltage Vba 1 after the precharging if the charge current Ip during the precharging is equal to or smaller than Imax.
In still another embodiment of the invention, the first step includes a step of measuring an ambient temperature Ta prior to the charging of the secondary battery, and the first charge voltage Vch 1 , the second charge voltage Vch 2 , the third charge voltage Vch 3 , and the fourth charge voltage Vch 4 have negative characteristics with respect to the ambient temperature Ta.
In another aspect of the invention, there is provided a method for charging a lead secondary battery including a positive grid of Pb—Ca alloy and an electrolytic solution including a diluted sulfuric acid having a specific gravity equal to or greater than about 1.280 at about 20° C., the method including: controlling a charge voltage so as to be about 2.40 V/cell or less where a discharge depth of the lead secondary battery is about 50% or less of a rated capacity of the lead secondary battery.
In one embodiment of the invention, a battery value immediately after the charging is begun is used as a parameter indicating the discharge depth.
In another embodiment of the invention, a charge time which elapses from the beginning of charging until attaining a predetermined battery value is used as a parameter indicating the discharge depth.
In still another embodiment of the invention, the charge voltage is controlled so as to maintain negative characteristics with respect to an ambient temperature at which the charging is performed.
In still another embodiment of the invention, the lead secondary battery includes a sealed-type lead secondary battery which absorbs an oxygen gas at a negative plate of the sealed-type lead secondary battery, the oxygen gas being generated from a positive plate of the sealed-type lead secondary battery.
In yet another aspect of the invention, there is provided a method for charging a secondary battery by controlling a charge voltage so as to be equal to or lower than a predetermined control voltage value, wherein the control voltage value is controlled so as to maintain negative characteristics with respect to an ambient temperature at which the charging is performed, and to maintain positive characteristics with respect to a discharge depth of the secondary battery.
In one embodiment of the invention, a parameter indicating the discharge depth is selected from a charge voltage value at the beginning of charging and a time which elapses from the beginning of charging until the charge voltage increases to a predetermined voltage.
In yet another aspect of the invention, there is provided a charging device for charging a secondary battery including: a charge voltage control section for controlling a charge voltage so as to be equal to or lower than a predetermined control voltage value, an ambient temperature measurement section for measuring an ambient temperature during the charging; and a discharge depth detection section for detecting a discharge depth of the secondary battery wherein the charge voltage control section controls the control voltage value so as to maintain negative characteristics with respect to the ambient temperature measured by the ambient temperature measurement section, and to maintain positive characteristics with respect to the discharge depth measured by the discharge depth detection section.
In one embodiment of the invention, the discharge depth detection section includes means for measuring a parameter selected from a charge voltage value at the beginning of charging and a time which elapses from the beginning of charging until the charge voltage increases to a predetermined voltage, and the discharge depth detection section detects the discharge depth by using the measured parameter.
In yet another aspect of the invention, there is provided a method for charging a lead secondary battery including: a first step of detecting a discharge state of the lead secondary battery; and a second step of subjecting the lead secondary battery to a constant-voltage charging if the detected discharge state is shallow as compared to a predetermined discharge state, and subjecting the lead secondary battery to a constant-current charging if the detected discharge state is deep as compared to the predetermined discharge state.
In one embodiment of the invention, the second step includes detecting the discharge state based on a parameter which is selected from a charge voltage value at the beginning of charging and a time which elapses from the beginning of charging until attaining a predetermined charge voltage.
Thus, the invention described herein makes possible the advantage of providing a charger (charging device) for cycle services which is capable of preventing the problem of shortened lifetimes which is typical of sealed-type lead secondary batteries, independent of how a device associated with a sealed-type lead secondary battery is used by a user.
This and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a flowchart illustrating a charge method for a secondary battery according to a first embodiment of the present invention.
FIG. 1B is a block diagram illustrating a charger for a secondary battery according to the first embodiment of the invention.
FIG. 2 is a detailed flowchart illustrating the charge method for a secondary battery according to the first embodiment of the present invention.
FIG. 3 is a graph illustrating a charge pattern of the first charging performed in the first charge mode in the charge method for a secondary battery according to the first embodiment of the present invention.
FIG. 4 is a graph illustrating a charge pattern of the second charging performed in the second charge mode in the charge method for a secondary battery according to the first embodiment of the present invention.
FIG. 5 is a graph illustrating the respective cycle life characteristics of a sealed-type lead secondary battery obtained by using the charge method according to the first embodiment of the present invention and a charge method according to a conventional example.
FIG. 6 is a graph illustrating the respective capacity recovery characteristics of a sealed-type lead secondary battery which has been overdischarged, obtained by using the charge method according to the first embodiment of the present invention and a charge method according to a conventional example.
FIG. 7 is a graph illustrating the charge characteristics according to the second embodiment of the present invention.
FIG. 8 is a graph illustrating a modification of the charge characteristics according to the second embodiment of the present invention.
FIG. 9 is a graph illustrating the results of a cycle life test with respect to various positive grid alloys, electrolytic solutions with various specific gravity values, and various discharge depths in a preliminary experiment according to the second embodiment of the present invention.
FIG. 10 is a graph illustrating the results of a cycle life test with respect to various charge control voltages and various discharge depths in a preliminary experiment according to the second embodiment of the prevent invention.
FIG. 11 is a graph illustrating the results of a cycle life test with respect to various discharge depths, obtained by the charge method according to the second embodiment of the present invention and a charge method according to a conventional example.
FIG. 12 is a graph illustrating the charge characteristics of a conventional constant-voltage charge method.
FIG. 13 is a flowchart illustrating a charge method according to a third embodiment of the present invention.
FIG. 14 is a graph illustrating the charge characteristics according to the third embodiment of the present invention.
FIG. 15 is a flowchart illustrating a modification of the charge method according to the third embodiment of the present invention.
FIG. 16 is a graph illustrating the charge characteristics according to a modification of the third embodiment of the present invention.
FIG. 17 is a graph illustrating the charge characteristics of a conventional constant-voltage charge method.
FIG. 18 is a graph illustrating the respective cycle life characteristics of a secondary battery obtained by using the charge method according to the third embodiment of the present invention and a charge method according to a conventional example.
FIG. 19 is a graph illustrating the charge characteristics according to a fourth embodiment of the present invention.
FIG. 20 is a graph illustrating the charge characteristics according to one modification of a fourth embodiment of the present invention.
FIG. 21 to a graph illustrating the respective cycle characteristics according to the fourth embodiment of the present invention and Conventional Examples 1 and 2.
FIG. 22 is a graph illustrating the charge characteristics of a conventional constant-voltage charge method.
FIG. 23 is a graph illustrating the charge characteristics of a conventional constant-current charge method.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment of the Invention
Hereinafter, a method for charging a secondary battery according to a first embodiment of the present invention will be described with reference to the accompanying figures.
FIG. 1A is a flowchart illustrating a charge method for a secondary battery according to a first embodiment of the present invention. It is assumed that the secondary battery to be charged in the illustrative embodiment is a sealed-type lead secondary battery.
Prior to charging the sealed-type lead secondary battery, a secondary battery voltage Vba 0 and an ambient temperature Ta are measured (S 101 ). Next, the sealed-type lead secondary battery is precharged (S 102 , S 103 ). After an interval of about 5 seconds, a secondary battery voltage Vba 1 is measured (S 105 ).
Then, the secondary battery voltage Vba 1 is compared against a first prescribed voltage V 1 , a second prescribed voltage V 2 , and a third prescribed voltage V 3 , where V 3 <V 2 <V 1 .
If the secondary battery voltage Vba 1 is between the first prescribed voltage V 1 and the second prescribed voltage V 2 , a first charging in a first charge mode is performed (S 106 ). If the battery voltage Vba 1 is between the second prescribed voltage V 2 and the third prescribed voltage V 3 , a second charging in a second charge mode is performed (S 107 ).
If the secondary battery voltage Vba 1 is lower than the third prescribed voltage V 3 , an active charging is performed (S 108 ). A cycle consisting of an active charging and an ensuing measurement of the secondary battery voltage Vba 2 is repeated, within a predetermined cycle limit, until the secondary battery voltage Vba 2 becomes higher than the third prescribed voltage V 3 . If the secondary battery voltage Vba 2 becomes higher than the third prescribed voltage V 3 within the predetermined cycle limit, a second charging in the second charge mode is performed (S 108 , S 107 ). If the secondary battery voltage Vba 2 has not become higher than the third prescribed voltage V 3 within the predetermined cycle limit, the charge operation for the sealed-type lead secondary battery is terminated (S 108 ).
If the secondary battery voltage Vba 1 is higher than the first prescribed voltage V 1 , or if the secondary battery voltage Vba 1 is lower than a fourth prescribed voltage V 4 (where V 4 <V 3 ), the charge operation is terminated (S 110 , S 109 ).
In the case where the second secondary battery voltage Vba 0 is equal to or greater than a prescribed voltage V 5 , either one of the following operations occurs: If a charge current Ip during the aforementioned precharging is equal to or smaller than Imax and equal to or greater than Imin (where Imin>0), the secondary battery voltage Vba 1 after the precharging is measured (S 103 ). If the charge current Ip during the precharging is greater than Imax, a warning message in displayed to indicate abnormal operation of the charger (charging device) and the charge operation is terminated (S 103 ). If the charge current Ip during the precharging is smaller than Imin, a warning message is displayed to indicate abnormality of the battery and the charge operation is terminated (S 103 ).
In the case where the secondary battery voltage Vba 0 is lower than the fifth prescribed voltage V 5 , either one of the following operations occurs: If the charge current Ip during the aforementioned precharging is greater than Imax, a warning message is displayed to indicate abnormal operation of the charger (charging device) and the charge operation is terminated (S 102 ). If the charge current Ip during the precharging is equal to or smaller than Imax, the secondary battery voltage Vba 1 after the precharging is measured (S 102 ).
FIG. 1B is a block diagram illustrating a charger (charging device) 100 for a secondary battery 101 according to the present embodiment of the invention.
The secondary battery charger 100 includes a charge voltage control section 104 for controlling the charge voltage of the secondary battery 101 at a level which is equal to or smaller than a predetermined value, an ambient temperature measurement section 102 for measuring the ambient temperature Ta during charging, a discharge depth detection section 103 for detecting the depth of discharge of the secondary battery 101 , and a power supply section 105 for supplying power to the charge voltage control section 104 .
The charge voltage control section 104 controls the charge voltage so as to maintain negative characteristics with respect to the ambient temperature Ta which is measured by the ambient temperature measurement section 102 , and to maintain positive characteristics with respect to the discharge depth detected by the discharge depth detection section 103 .
As used herein, a parameter value is said to have or maintain “positive characteristics” with respect to another parameter value when the former parameter value varies in proportion with the latter parameter value. Similarly, a parameter value is said to have or maintain “negative characteristics” with respect to another parameter value when the former parameter value varies in inverse proportion with the latter parameter value.
The discharge depth detection section 103 measures either the charge voltage at the beginning of the charge operation or the time which elapses between the beginning of the charge operation and the point at which the charge voltage reaches a predetermined voltage. The discharge depth detection section 103 detects the discharge depth by utilizing as a parameter either the charge voltage at the beginning of the charge operation or the time which elapses between the beginning of the charge operation and the point at which the charge voltage reaches the predetermined voltage.
FIG. 2 is a detailed flowchart illustrating the charge method for a secondary battery according to the first embodiment of the present invention.
First, the secondary battery voltage Vba 0 of the secondary battery in an open circuitry state is measured, and the ambient temperature Ta of a surrounding area of the secondary battery is measured (S 201 ). The temperature measurements can be taken by a thermistor, for example.
After the measurement of the secondary battery voltage Vba 0 , a precharging is performed for a predetermined period of time using the charge current Ip (S 203 , S 204 ). According to the present embodiment, measurements of the charge current Ip are utilized to detect an abnormality of the charger or the battery. Specifically, the secondary battery voltage Vba 0 which was measured before the precharging is compared against the fifth prescribed voltage V 5 (S 202 ).
If the secondary battery voltage Vba 0 is lower than the fifth prescribed voltage V 5 and the charge current Ip during the aforementioned precharging is greater than Imax (as indicated by Ip>Imax at S 209 ), or if the secondary battery voltage Vba 0 is equal to or greater than the fifth prescribed voltage V 5 and the charge current Ip during the aforementioned precharging is smaller than Imin (as indicated by Ip<Imin at S 205 ), then the charge operation is terminated (S 210 , S 206 ). This makes it possible to detect secondary batteries which have internal short-circuiting and/or secondary batteries which have deteriorated through excessive charging and discharging.
If the secondary battery voltage Vba 0 which was measured before the precharging is equal to or greater than the fifth prescribed voltage V 5 and the charge current Ip is greater than Imax, the charger is determined to be in an abnormal state and the charge operation is terminated (as indicated by Ip>Imax at S 205 ).
After a predetermined interval following completion of the precharging, the secondary battery voltage Vba 1 in an open circuitry state is measured (S 207 , S 208 , S 211 ). The present invention relies on the value of the secondary battery voltage Vba 1 to determine the state (especially the discharge state) of the secondary battery.
As mentioned above, it is preferable to measure the secondary battery voltage Vba 1 after a predetermined interval following completion of the precharging. It should be noted that determining the discharge state of the secondary battery based on a charge voltage value required during charging of the secondary battery, for example, might load to misdetection. The reason is that the charge voltage of the secondary battery may increase in the case where the secondary battery is overdischarged or left unused for a long period of time, and such an increased charge voltage may falsely produce an indication that the charging for the secondary battery is complete.
On the other hand, if the discharge state is determined based only on the secondary battery voltage in an open circuitry state, without performing any precharging, a large fluctuation may occur in the results of discharge state determination. The reason is that it is possible for secondary batteries which now have the same discharge state to later have various open circuitry voltages, depending on how the respective secondary batteries have been stored or maintained.
The aforementioned phenomenon will be further described. If a lead secondary battery which is in a certain discharge state is left unused, a thin layer of lead sulfate may form especially on the surface of the negative active material due to the self-discharging. Since such a layer in itself has a small self-discharge amount, the discharge state does not substantially change after the secondary battery has been left unused. However, the potential of the negative plate increases anodically so as to lower the secondary battery voltage.
In such cases, determining the discharge state based only on the open circuitry voltage of the secondary battery will falsely indicate too large a discharge depth for the actual discharge state, thereby preventing appropriate charging. Furthermore, the secondary battery voltage immediately after discharging is unstable due to concentration polarization of the electrolytic solution. Employing such an unstable voltage for the discharge state determination will greatly degrade the.
According to the present invention, the secondary battery voltage Vba 1 in an open circuitry state is measured after a predetermined interval following completion of the precharging. As a result, the fluctuation in the results of discharge state determination is minimized so as to enable accurate discharge state determination. The precharging acts to reduce the thin layer of lead sulfate which has been generated due to slight self-discharging, and promotes the elimination of concentration polarization immediately after discharging, thereby making it possible to obtain a secondary battery voltage in an open circuitry state which reflects the actual discharge state.
According to the present invention, the secondary battery voltage Vba 1 is used as a parameter for controlling the charge operation. Specifically, if the secondary battery voltage Vba 1 is between the first prescribed voltage V 1 and the second prescribed voltage V 2 (where V 2 <V 1 ), the discharge state of the secondary battery is determined as “shallow”, and accordingly a first charging (charging 1 ) by a first charge mode is performed (S 212 ).
If the secondary battery voltage Vba 1 is between the second prescribed voltage V 2 and the third prescribed voltage V 3 (where V 3 <V 2 ), the discharge state of the secondary battery is determined as “deep”, and accordingly a second charging (charging 2 ) by a second charge mode is performed (S 213 ).
If the secondary battery voltage Vba 1 is even lower than the third prescribed voltage V 3 , the secondary battery is determined as having low charging acceptance due to overdischarging and the like, and accordingly an active charging is performed (S 214 ). The active charging can be performed, for example, by using a constant current for a short period of time, so as to charge the passivation layer between the positive grid and the positive active material formed due to overdischarging and the enlarged lead sulfate (which has low charging acceptance) formed while the secondary battery has been left unused for a long time. Thus, the secondary battery can be revived for further charging.
After the active charging, the secondary battery is now considered as having a “deep” discharge state, so that it is subjected to a second charging (charging 2 ) in the second charge mode.
Depending on the extent of overdischarging and how long the battery has been left unused, the secondary battery may not be revived through a single active charging. Therefore, a cycle consisting of an active charging and an ensuing measurement of the secondary battery voltage Vba 2 in an open circuitry state is repeated, within a predetermined cycle limit (N cycles), until the secondary battery voltage Vba 2 becomes higher than the third prescribed voltage V 3 . Once the third secondary battery voltage Vba 2 has become higher than the third prescribed voltage V 3 within the predetermined cycle limit (N cycles), a second charging (charging 2 ) in the second charge mode is performed (S 215 , S 216 , S 217 , S 213 ). If the third secondary battery voltage Vba 2 has not become higher than the third prescribed voltage V 3 within the predetermined cycle limit (N cycles), secondary battery abnormality or exhaustion is determined and the charge operation for the sealed-type lead secondary battery is terminated (S 210 ).
For further security during the charge operation, it is preferable to determine charger abnormality or secondary battery abnormality/exhaustion if the secondary battery voltage Vba 1 after the completion of precharging is higher than the first prescribed voltage V 1 , or if the secondary battery voltage Vba 1 is lower than the fourth prescribed voltage V 4 (where V 4 <V 3 ), and to terminate the charge operation (S 206 , S 210 ).
Next, a preferred embodiment of the first charging (charging 1 ) (S 212 ) in the firat charge mode and the second charging (charging 2 ) (S 213 ) in the second charge mode are described with reference to FIGS. 3 and 4.
FIG. 3 is a graph illustrating a charge pattern of the first charging (charging 1 ) in the first charge mode. The first charging (charging 1 ) begins with a constant current charging (initial charge current: Ii(A)) in accordance with a first control voltage Vch 1 . After the charge voltage of the secondary battery has reached the control voltage Vch 1 , the charge current is decreased in accordance with a constant-voltage control. Once the charge current has decreased to a predetermined value Ia, the control voltage Vch 1 for the charging is reduced to Vch 2 , where Vch 2 <Vch 1 . As a result, overcharging due to charging a secondary battery which has only experienced shallow discharging is prevented, thereby minimizing the decrease in the secondary battery lifetime.
FIG. 4 is a graph illustrating a charge pattern of the second charging (charging 2 ) in the second charge mode. The second charging (charging 2 ) begins with a constant current charging (initial charge current: Ii(A)) in accordance with a third control voltage Vch 3 . After the charge voltage of the secondary battery has reached the third control voltage Vch 3 , the charge current is decreased in accordance with a constant-voltage control. Once the charge current has decreased to a predetermined value Ib, a constant-current charging is performed by using a current value Ic for a predetermined period of time. It will be appreciated that Ib and Ic may be of equal values.
The constant-current charging with the current value Ic prevents undercharging due to charging a secondary battery which has experienced deep discharging, thereby maximizing the lifetime of the secondary battery. Following the constant-current charging, charging is continued with a control voltage Vch 4 , where Vch 4 <Vch 3 .
The same value may be prescribed for both of the initial control voltages Vch 1 and Vch 3 used in the first charge mode and the second charge mode, respectively. In view of charging acceptance as a function of the ambient temperature during charging, it is preferable to control the control voltages Vch 1 and Vch 3 so as to maintain negative characteristics with respect to the ambient temperature Ta measured prior to the charging, thereby maximizing the effects attained by the present invention.
It is also possible to prescribe the same value for the second control voltage Vch 2 and the fourth control voltage Vch 4 so that the relevant portion of the charge voltage control section can be used in both the first charge mode and the second charge mode, thereby effectively reducing the charger cost. It is also preferable to control the control voltages Vch 2 and Vch 4 so as to maintain negative characteristics with respect to the ambient temperature Ta.
First Embodiment of the Invention—Example 1
Referring to FIG. 5, Example 1 of a first embodiment of the present invention will be described.
The inventors conducted charge/discharge cycle life tests on a sealed-type lead secondary battery which had a nominal voltage of 24 V and a 10-hour rated capacity of 28 Ah by using the charge method according to the first embodiment of the invention.
The following parameter values were used in the tests:
Current value during precharging
Ip: 0.6 A
Imax: 0.7 A
Imin: 0.2 A
Precharging: 10 sec.
Measurement timing for secondary battery voltage Vba 1 :
5 sec. after completion of precharging
first prescribed voltage V 1 : 34 V
second predscribed voltage V 2 : 24 V
third prescribed voltage V 3 : 20 V
fourth prescribed voltage V 4 : 2 V
fifth prescribed voltage V 5 : 20 V
initial charge current Ii: 5 A
first control voltage Vch 1 : 29.4-0.06(Ta-25)
second control voltage Vch 2 : 27.6-0.06(Ta-25)
predetermined current Ia: 0.6 A
third control voltage Vch 3 : 29.4-0.06(Ta-25)
fourth control voltage Vah 4 : 27.6-0.06(Ta-25)
current value Ib: 0.6 A
current value Ic: 0.6 A
active charge current: 0.6 A
active charge time: 15 min./cycle
cycle limit for active charge N: 9 cycles
(In the above parameter conditions, Ta represents the ambient temperature (° C.).)
Three discharge conditions A, B, and C were used in the test:
Condition A (indicated as A in FIG. 5 ):
perform discharge {circle around (1)} (discharge for 2.4 hs with a constant current of 7 A (about 60% discharge of the rated capacity)).
Condition B (indicated as B in FIG. 5 .):
perform discharge {circle around (2)} (discharge for 22 min with a constant current of 7 A (about 10% discharge of the rated capacity)).
Condition C (indicated as C in FIG. 5 ):
perform discharge {circle around (1)} for odd-numbered cycles and perform {circle around (2)} for even-numbered cycles.
As conventional examples, tests were conducted for the same 24 V/28 Ah secondary battery (described above) but using discharge conditions D, E, F, and G as follows:
Condition D (indicated as D in FIG. 5 ):
perform discharge {circle around (1)}, followed by a charging 1 in the first charge mode alone.
Condition E (Indicated as E in FIG. 5 ):
perform discharge {circle around (1)}, followed by a charging 2 in the second charge mode alone.
Condition F (indicated as P in FIG. 5 ):
perform discharge {circle around (2)} followed by a charging 1 in the first charge mode alone.
Condition G (indicated as G in FIG. 5 ):
perform discharge {circle around (2)}, followed by a charging 2 in the second charge mode alone.
Each test was performed for a charge time of 12 hours. The capacity of the secondary battery was measured by allowing the secondary battery to completely discharge down to 21 V (with 7 A) per every 20 cycles. The results of these test are shown in FIG. 5 .
From the results shown in FIG. 5, it can be seen that, in accordance with the first embodiment of the invention, appropriate charging can always be performed by detecting any change in the discharge depth of the sealed-type lead secondary battery used. In accordance with the invention. all of the tested sealed-type lead secondary batteries stably exhibit a lifetime of about 450 to about 500 cycles without substantial variation.
In accordance with the conventional examples, however, the battery lifetime is under a large influence by the discharge depth and the charge method, resulting in a variety of lifetimes from about 150 to about 500 cycles. Such instability indicates that short lifetimes may be incurred due to variation in the manner In which a device associated with such a sealed-type lead secondary battery is used by a user.
First Embodiment of the Invention—Example 2
Next, a overdischarged battery was prepared by coupling the 24 V/28 Ah sealed-type lead secondary battery employed in Example 1 to a fixed resistor of 2Ω for 24 hours, after which the secondary battery was left unused for 1 month. Thereafter, this overdischarged battery was subjected to a 5-cycle process, where each cycle consisted of a charging in accordance with Example 1 of the first embodiment of the invention and a constant-current (7 A) discharging (final voltage: 21 V) (condition H; indicated as H in FIG. 6 ).
As a conventional example, a similarly-prepared overdischarged battery was subjected to a 5-cycle process, where each cycle consisted of a charging 2 in the second charge mode alone and a constant-current (7 A) discharging (final voltage: 21 V) (condition I; indicated as I in FIG. 6 ). The results of these test are shown in FIG. 6 .
From the results shown in FIG. 6, it can be seen that, in accordance with the first embodiment of the invention, a sufficient discharge capacity is already attained at the first cycle. On the other hand, the conventional example takes three cycles to attain the level of discharge capacity that is attained at the first cycle in accordance with the first embodiment of the invention.
Thus, in accordance with the first embodiment of the invention, overdischarging of a secondary battery in detected, upon which the secondary battery in subjected to active charging. The active charging serves to restore sufficient capacity within a relatively few cycles. As a result, unwanted and unexpected decrease in the capacity of the secondly battery can be prevented for the convenience of the user of a device associated with the secondary battery.
Thus, in accordance with the first embodiment of the invention, appropriate charging can always be performed by detecting any user-induced variation in the discharge depth of a secondary battery (in particular a sealed-type lead secondary battery). An a result, the sealed-type lead secondary battery can enjoy an enhanced longevity, thereby making a substantial contribution in the industry.
Second Embodiment of the Invention
Hereinafter, a method for charging a secondary battery according to a second embodiment of the present invention will be described with reference to the accompanying figures.
FIG. 7 is a graph illustrating the charge characteristics of the charge method according to the second embodiment of the invention. First, a constant-current charging with an initial charge current Is is performed for a lead secondary battery. The charge voltage (Vs) immediately after the charging in begun is measured. The value of Vs is compared against a discharge depth reference voltage (Vc). If Vs≧Vc, a shallow discharge state is determined (i.e., discharge depth of about 50% or less).
Then, a constant-voltage charge is performed by using a control voltage V 1 (≦2.4 V/cell; indicated by the solid line in FIG. 7) which is lower than the charge control voltage V 2 for a deep discharge state (indicated by the broken line in FIG. 7 ). It is preferable to employ a timer so that the charge is terminated after the lapse of a predetermined period of time (T 2 ) from the point at which the charge voltage reaches a predetermined value (V 3 ), for example, in order to secure a proper charge electricity amount within a predetermined charge time.
Toward the same end, it is also possible to prescribe shorter charge times T 2 , T 3 as a higher charge control voltage is employed. It is preferable that the respective control voltages satisfy V 3 <V 1 , V 2 to ensure a secure detection despite any fluctuation in the detected voltage, although It is also applicable to use V 3 =V 1 , V 2 .
Second Embodiment of the Invention—Modification
FIG. 8 is a graph illustrating one modification of the charge pattern according to the second embodiment of the present invention, where a different method for determining the discharge depth is employed. Specifically, a constant-current charging is performed with an initial charge current (Is), and the time (T 4 ) which elapses from the beginning of charging until the charge voltage reaches a predetermined voltage value (V 4 ) is measured. The measured time T 4 is compared against a discharge depth reference time (Tc). If T 4 ≦Tc, a shallow discharge state is determined (i.e., discharge depth of about 50% or less). Thereafter, the charging is controlled in the same manner as in the case of Vs≧Vc in the second embodiment of the invention.
In the above-described second embodiment of the invention and the modification thereof, the charge control which is performed in the case of determining a shallow discharge state (i.e., discharge depth of about 50% or less) is illustrated as a single level constant-voltage control using a timer. However, the present invention is not limited thereto; multiple levels of constant-voltage control may be performed depending on the value of Vs or T 4 for even better charging.
Second Embodiment of the Invention—Example 1
For a preliminary experiment, a cycle life test was performed for 12 V/30 Ah lead secondary batteries by using a conventional charge method illustrated in FIG. 12 . The charge method employed a charge control voltage V 1 of 15.0 V (at 25° C.), a maximum charge current of 5.0 A, and a charge time of 12 hours, The discharge was performed to various discharge depths by varying the discharge time with a constant current of 7.5 A. The charging and discharging were repeated.
After every 50 cycles of these charging and discharging, the capacity of each battery was checked by subjecting the battery to complete discharge with a constant current of 7.5 A, down to a final voltage of 10.5 V. The exhaustion, or expiration of lifetime, of the battery was determined when the discharge capacity reached about 50% or lose of the initial value.
As a positive grid alloy, the tested batteries incorporated either a Pb—Ca(0.08%)-Sn(1.0%) alloy, which is a conventionally employed Pb—Ca type alloy, or a Pb—Sb (3.0%)-As(0.2%) alloy, which is a Pb—Sb type alloy mainly employed for liquid-type lead secondary batteries.
An electrolytic solution having a specific gravity of 1.320 (20° C.) was used for the lead secondary batteries incorporating a Pb—Sb type positive grid alloy. Various electrolytic solutions having a specific gravity of 1.260 to 1.340 were used for the lead secondary batteries incorporating a Pb—Ca type positive grid alloy in order to confirm the influence of the specific gravity of the electrolytic solution on the cycle life.
The results are shown in FIG. 9 . As seen from FIG. 9, a decrease in the cycle life of the lead secondary batteries incorporating a Pb—Ca type positive grid alloy was observed in a region corresponding to an electrolytic solution specific gravity of 1.280 or more (20° C.) and a discharge depth of about 50% or less. This decrease in the cycle life was caused by a decrease in the capacity of the positive plate. Moreover, a passivated accumulation of lead sulfate was observed near the interface between the positive active material, which had been converted into lead dioxide through charging, showed softening presumably due to overcharging. It is presumed, without certainty, that unevenness in the discharge distribution due to partial discharge is involved in the softening of the positive active material.
Next, a cycle life test was performed by employing various charge control voltages in the above-described preliminary experiment. The results are shown in FIG. 10 . The batteries used in the test incorporated a Pb—Ca type positive grid alloy, and an electrolytic solution having a specific gravity of 1.320 at 20° C. was used.
From the results shown in FIG. 10, it can be seen that the decrease in the cycle life is reduced by employing a charge control voltage of 2.40 V/cell or less in a region corresponding to a discharge depth of about 50% or less, while a conspicuous decrease in the cycle life was observed in a region corresponding to large discharge depths due to insufficient charging. The reduced decrease in the cycle life in the region corresponding to small discharge depths was presumably a result of a relatively uniform charge reaction, which was made possible by lowering the charge voltage to about 2.40 V/cell.
In the case of employing a high charge voltage, where a large extent of anodic polarization of the positive plate occurs during charging, a charge reaction progresses in a region with relatively high charging acceptance. However, in other regions, the generation of gaseous oxygen may occur rather than an oxidation reaction into lead dioxide, thereby resulting in an accumulation of lead sulfate. It in also presumable that the portion which has been converted into lead dioxide is subjected to charging with an increased priority, thereby resulting in overcharging and hence reduced lifetime.
In the second embodiment of the invention where a charge control voltage of 2.40 V/cell or less is employed, it is predicated that a small degree of anodic polarization exists so that the charge react on progresses in a relatively slow and uniform manner. This presumably causes the unevenly distributed lead sulfate (which resulted due to a partial reaction) to effectively react into lead dioxide, thereby substantially eliminating overcharging in other portions and minimizing the decrease in cycle life.
Thus, it has been confirmed that the method according to the present embodiment of controlling the charge voltage by detecting the discharge depth in applications which may result in various discharge depths can effectively minimize the decrease in cycle life.
Second Embodiment of the Invention—Example 2
Cycle life tests were conducted for the aforementioned 12V/30 Ah lead secondary batteries in an atmosphere at a temperature of 25° C., by employing charge methods according to the second embodiment of the invention as illustrated in FIG. 7 and according to a conventional charge method for comparison.
{circle around (1)} The charge method according to the second embodiment of the invention was performed under the conditions of:
initial charge current (Is)=5.0 A;
discharge depth reference voltage (Vc)=12.0 V;
and, (a) in the case where Vs≧Vc (where Vs is the charge voltage immediately after the charging is begun), the following conditions were used:
charge control voltage (V 1 )=14.1 V (2.35 V/cell)
charge time: A timer is started when the charge voltage reaches V 3 (=14.0 V) and the charging is terminated in 8 hours after the timer is started;
or (b) in the case where Vs<Vc, the following conditions were used:
charge control voltage (V 1 )=15.0 V (2.50 V/cell)
charge times: A timer is started when the charge voltage reaches V 3 (=14.0 V) and the charging is terminated in 8 hours after the timer is started.
{circle around (2)} The conventional charge method was performed under the conditions of:
initial charge current (Is)=5.0 A;
charge control voltage=14.7 V; and
charge time=12 hours.
By employing the charge method according to Example 2 of the second embodiment of the invention and by employing the conventional charge method an described above, cycle life comparative tests were conducted with respect to electrolytic solutions with various specific gravity values, various positive grid alloys, and various discharge depths. The results are shown in FIG. 11 .
From the results shown in FIG. 11, it can be seen that the decrease in cycle life, in the problematic region corresponding to a discharge depth of about 50% or less, was successfully minimized for lead secondary batteries employing a Pb—Ca type positive grid alloy and an electrolytic solution with a specific gravity of 1.280 or more. Incidentally, the charge electricity amount in a region corresponding to small discharge depths indicated an excellent value of about 105% to about 113% of the discharge electricity amount, with substantial stability.
It is preferable to change the charge control voltage value with respect to a reference discharge depth of about 50%. This charge method is especially useful for lead secondary batteries incorporating a Pb—Ca type positive grid alloy. It will be appreciated that the charge method according to the second embodiment of the invention is very useful especially for sealed-type lead secondary batteries, which cannot incorporate a Pb—Sb type positive grid alloy for structural reasons.
As has been described with respect to the aforementioned modification of the second embodiment of the invention, in accordance with Example 2 of the second embodiment of the invention, the time which elapses from the beginning of charging until the charge voltage reaches a predetermined voltage value can be used as a parameter to indicate the discharge depth because the elapsed time will decrease as the discharge depth becomes small and the time will increase as the discharge depth becomes large.
Although the present example employe a discharge depth reference voltage Vs of 12.0 V, this value is susceptible to changes depending on various design factors of each individual secondary battery and should be adjusted according to such design factors. Similarly, the time which elapses from the beginning of charging until the charge voltage reaches a predetermined voltage value should be determined according to such design factors.
It will be appreciated that it is preferable to prescribe the control voltage values so as to maintain negative characteristics with respect to the ambient temperature Ta. The reason is that an increase in the ambient temperature Ta, even with the same charge control voltage, may result in the same behavior as if there is enhanced polarization, for example. This must be compensated for by decreasing the charge voltage.
Thus, according to the charge method of the second embodiment of the invention, the decrease in cycle life, in the region corresponding to a small discharge depth, can be minimized for lead secondary batteries employing a Pb—Ca type positive grid alloy and an electrolytic solution with a specific gravity of 1.280 or more at 20° C. The charge method according to the second embodiment of the invention is very useful especially for sealed-type lead secondary batteries, for which a Pb—Ca type positive grid alloy is indispensable.
Third Embodiment of the Invention
FIG. 13 is a flowchart illustrating a charge method according to a third embodiment of the present invention. First, the secondary battery is charged with an initial charge current Is (S 1301 ). A charge voltage Vs immediately after the charging is begun is measured (S 1302 ). The Vs value is compared against a discharge depth reference voltage Vr (S 1303 ). If Vs is equal to or greater than Vr, the discharge depth is determined as small (i.e. “shallow”) so that the charge control voltage Vc is decreased (S 1305 ). If Vs is lower then Vr, the discharge depth is determined as large (i.e., “deep”) so that the charge control voltage Vc is increased (S 1304 ).
FIG. 14 is a graph illustrating the charge characteristics according to the third embodiment of the present invention, where the solid line indicates the case where a deep discharge depth is determined and the broken line indicates the case where a shallow discharge depth is determined.
Third Embodiment of the Invention—Modification
FIG. 15 is a flowchart illustrating a modification of the charge method according to the third embodiment of the present invention.
First, the secondary battery is charged with an initial charge current Is (S 1501 ), and a timer is started to measure time (S 1502 ). The timer stops as the charge voltage reaches a predetermined voltage Va, thereby measuring the time Tt which elapses from the beginning of charging until the charge voltage reaches Va (S 1503 ). The time Tt is compared against a discharge depth reference time Tr (S 1504 ). If Tr is greater than Tt, the discharge depth is determined as large (i.e. “deep”) so that the charge control voltage Vc is increased (S 1505 ). If Tr is equal to or smaller than Tt, the discharge depth to determined as small (i.e. “shallow”) so that the charge control voltage Vc is decreased (S 1506 ).
FIG. 16 is a graph illustrating the charge characteristics according to the present modification of the third embodiment of the invention, where the solid line indicates the case where a deep discharge depth is determined and the broken line indicates the case where a shallow discharge depth is determined.
In the above-described third embodiment of the invention and the modification thereof, it is preferable to determine the discharge depth so that a discharge depth which in larger than about 30% to about 50% of the rated capacity is determined an deep and that a discharge depth which is smaller than about 30% to about 50% of the rated capacity is detained as shallow, in order to minimize the decrease in the lifetime of the secondary battery.
Instead of the above-described discharge depth dichotomy of either “deep” or “shallow” as determined with respect to a predetermined reference value, it is more preferable to continuously vary the charge control voltage Vc relative to the discharge depth parameter Tt or Vs. Furthermore, as is practiced in conventional constant-voltage charge control methods, it is desirable to prescribe the control voltage values so as to maintain negative characteristics with respect to the ambient temperature.
FIG. 18 is a graph illustrating the results of respective cycle life tests for a sealed-type lead secondary battery (6 V/10 Ah) performed by using the charge method according to the third embodiment of the present invention and a conventional constant-voltage charge method illustrated in FIG. 17 . In the tests, the discharge depth was varied so as to be 10%, 20%, 30%, 40%, 50%, or 70% of the rated capacity. The charge control voltage value Vc and the discharge depth reference value Vr were prescribed so that the charge control voltage value was controlled to be 6.9 V at a discharge depth of about 40% or less and to be 7.35 V at a discharge depth of more than about 40%.
The conventional constant-voltage charge method was performed with a charge control voltage of 6.9 V or 7.35 V. In all of the charge methods performed in the tests, the charge current was 4 A, the charge time was 8 hours, and the charging was performed at an ambient temperature at 25° C. The results of these cycle life tests are shown in FIG. 18 .
As seen from the results shown in FIG. 18, the decrease in the cycle life associated with variation in the discharge depth is minimized by the charge method in accordance with the third embodiment of the invention as compared to the conventional constant-voltage charge method. The charge method according to the third embodiment of the invention always maintained a charge electricity amount equal to about 105% to 110% of the discharged electricity amount.
An additional cycle life test was conducted at an ambient temperature of 40° C., whereby it was confirmed that it is appropriate to impart the charge control voltage with negative characteristics at a rate of −0.0025 to 0.0035 V/cell · ° C. per increase of 1° C.
As described above, in accordance with the charge method of the third embodiment of the invention, appropriate charging control can always be made with a proper voltage regardless of variation in the discharge depth of the secondary battery. As a result, the problems of undercharging and overcharging associated with the conventional constant-voltage charge methods are alleviated so as to minimize the decrease in the cycle life of secondary batteries, thereby making a substantial contribution in the industry.
Fourth Embodiment of the Invention
Hereinafter, a method for charging a secondary battery according to a fourth embodiment of the present invention will be described with reference to the accompanying figures.
FIG. 19, is a graph illustrating the charge characteristics according to the fourth embodiment of the present invention. First, a lead secondary battery is charged with an initial charge current Is(A). A charge voltage (Vs) at the beginning of charging is measured. The Vs value is compared against a discharge depth reference Voltage Vc (S 1303 ). The charging is controlled depending on the relationship between the values of Vs and Vc as follows:
{circle around (1)} If Vs≧Vc (as indicated by the solid line in FIG. 19 ), a shallow discharge state is determined, and a constant-voltage charging is performed (with a control voltage V 2 ; indicated by the solid line in FIG. 19 ). It is preferable to employ a timer so that the charge is terminated after the lapse of a predetermined period of time (T 3 ) from the point at which the charge voltage reaches a predetermined value (V 1 ), for example, in order to secure a proper charge electricity amount. It is preferable that the respective control voltages satisfy V 1 <V 2 to ensure a secure detection despite any fluctuation in the detected voltage, although it is also applicable to use V 1 =V 2 .
{circle around (2)} If Vs<Vc (as indicated by the broken line in FIG. 19 ), a deep discharge state is determined, and a constant-current charging is performed (indicated by the broken line in FIG. 19 ). It is preferable to employ a timer so that the charge is terminated after the lapse of a predetermined period of time (T 4 ) from the point at which the charge voltage reaches the predetermined value (V 3 ) in order to prevent overcharging and secure a proper charge electricity amount.
Although the comparison results are divided into {circle around (1)} Vs≧Vc and {circle around (2)} Vs<Vc in the above example, it is also applicable to employ {circle around (1)} Vs>Vc and {circle around (2)} Vs≦Vc depending on the needs of the specific control method.
Fourth Embodiment of the Invention—Modification
FIG. 20 is a graph illustrating one modification of the charge pattern according to the fourth embodiment of the present invention, where a different method for determining the discharge depth is employed. Specifically, a constant-current charging is performed with an initial charge current (Is), and the time (T 5 ) which elapses from the beginning of charging until the charge voltage reaches a predetermined voltage value (V 4 ) is measured. The measured time T 5 is compared against a discharge depth reference time (Tc).
{circle around (1)} If T 5 ≧Tc (indicated by the broken line in FIG. 20 ), a deep discharge state is determined. Thereafter, the charging is controlled in the same manner as in the case of “{circle around (2)} Vs≧Vc” in the fourth embodiment of the invention.
{circle around (1)} If T 5 <Tc (indicated by the solid line in FIG. 20 ), a shallow discharge state is determined Thereafter, the charging is controlled in the same manner as in the case of “{circle around (1)} Vs≧Vc” in the fourth embodiment of the invention.
Although the comparison results are divided into {circle around (1)} T 5 ≧Tc and {circle around (2)} T 5 <Tc in the above example, it is also applicable to employ {circle around (1)} T 5 >Tc and {circle around (2)} T 5 ≦Tc depending on the needs of the specific control method, as in the fourth embodiment of the invention.
In the above-described fourth embodiment of the invention and the modification thereof, the charge control which is performed in the case of determining a shallow discharge state is illustrated as a single level constant-voltage control. However, the present invention is not limited thereto; for example, a two level constant-voltage control may be performed where the charge voltage is decreased upon detection of a decrease of the charge current. In the case of determining a deep discharge state, a two level constant-current charging may be performed where the charge current is decreased upon detection of an increase in the charge voltage V 3 , thereby further minimizing overcharging.
In a charger having the above-described charge characteristics, the control circuits for the constant-voltage charge and the constant-current charge can be constructed based on substantially the same circuitry. Therefore, such a charger can be realized by merely adding circuitry for detecting the charge voltages V 1 and V 2 at the beginning of the charging and circuitry for selecting either constant-voltage charging or constant-current charging.
Fourth Embodiment of the Invention—Example
The inventors conducted charge/discharge cycle life tests by using the charge method according to the fourth embodiment of the invention and by using conventional constant-voltage charging and constant-current charging methods.
The following parameter values were used in the tests:
Fourth Embodiment of the Invention—Charge Method According to the Fourth Embodiment of the Invention as Illustrated in FIG. 19
initial charge current Is: 4.5 A
discharge depth reference voltage Vc: 12.0 V
charge control voltage V 2 for a shallow discharge state: 14.7 V
(A timer is started when the charge voltage equals V 1 =14.5 V and the charging it terminated after a lapse of T 3 =10 h from the start of the timer)
charge control current for a deep discharge state: 4.5 A
(A timer is started when the charge voltage equals V 3 =14.5 V and the charging it terminated after a lapse of T 4 =1.5 h from the start of the timer)
Conventional Example 1—Constant-voltage Charge Method as Illustrated in FIG. 22
initial charge current: 4.5 A
charge control voltage: 14.7 V
charge time: 12 hs
Conventional Example 2—Constant-current Charge Method as Illustrated in FIG. 23
initial charge current: 4.5 A
(A timer is started when the charge voltage equals 14.5 V and the charging is terminated after a lapse of T 4 =1.5 h from the start of the timer)
By employing the charge methods according to the fourth embodiment of the invention and Conventional Examples 1 and 2, cycle life tests were conducted for sealed-type lead secondary batteries (12 V/30 Ah) by varying the discharge depth so as to be 5%, 10%, 30%, 60%, or 90% of the rated capacity. The results are shown in FIG. 21 .
As seen from the results shown in FIG. 21, the charge electricity amount was about 105% to about 115% of the discharge electricity amount, indicative of substantial stability, regardless of the discharge depth. The cycle life of the secondary batteries in a deep discharge state was greatly improved according to the fourth embodiment of the invention as compared to that obtained by the constant-voltage charging of Conventional Example 1. The cycle life of the secondary batteries in a shallow discharge state was greatly improved according to the fourth embodiment of the invention as compared to that obtained by the constant-current charging of Conventional Example 2.
Thus, in accordance with the charge method of the fourth embodiment of the invention, either constant-voltage charging or constant-current charging can be selected depending on the discharge state, so that a constant charge electricity amount relative to the discharged electricity amount can be provided irrespective of the discharge depths. As a result, a stable cycle life can be expected regardless of a deep or shallow discharge state. As seen from the results shown in FIG. 21, about 30% to about 50% of the rated capacity can be suitably used as a reference value for determining the discharge depth. It is preferable to determine the discharge depth so that a discharge depth which is larger than about 30% to about 50% of the rated capacity is determined an deep (so that a constant-current control is performed) and that a discharge depth which is smaller than about 30% to about 50% of the rated capacity is determined as shallow (so that a constant-voltage control is performed).
Thus, in accordance with the charge method of the fourth embodiment of the invention, a proper charge electricity amount can always be provided through appropriate charging control, regardless of variation in the discharge depth of the secondary battery, without causing undercharging or overcharging. As a result, the decrease in the cycle life of secondary batteries is minimized, thereby making a substantial contribution in the industry.
Thus, in accordance with the charge method of the present invention, appropriate charging can always be performed by detecting any user-induced variation in the discharge depth of a secondary battery (in particular a lead secondary battery). As a result, the sealed-type lead secondary battery can enjoy an enhanced longevity, thereby making a substantial contribution in the industry.
Thus, according to the charge method of the present invention, the decrease in cycle life, in the region corresponding to a small discharge depth, can be minimized for lead secondary batteries employing a Pb—Ca type positive grid alloy and an electrolytic solution with a specific gravity of 1.280 or more at 20° C. The charge method of the invention is very useful especially for sealed-type lead secondary batteries, for which g Pb—Ca type positive grid alloy is indispensable.
As described above, in accordance with the charge method of the present invention, appropriate charging control can always be made with a proper voltage regardless of variation in the discharge depth of the secondary battery. As a result, the problems of undercharging and overcharging associated with the conventional constant-voltage charge methods are alleviated so as to minimize the decrease in the cycle life of secondary batteries, thereby making a substantial contribution in the industry.
Thus, in accordance with the charge method of the present invention, a proper charge electricity amount can always be provided through appropriate charging control, regardless of variation in the discharge depth of the secondary battery, without causing undercharging or overcharging. As a result, the decrease in the cycle life of secondary batteries is minimized, thereby making a substantial contribution in the industry.
Various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but rather that the claims be broadly construed.
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A method for charging a secondary battery by measuring the static/open circuit voltage and comparing it to a predetermined value includes: a first step of precharging the secondary battery; thereafter pausing a predetermined interval; a step of measuring a secondary battery voltage Vba1 after performing the pausing; and a step of charging the secondary battery based on the measurement of the secondary battery voltage Vba1.
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BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to improvements in woodwind musical instrument mouthpieces, and in particular to improvements to the mouthpieces which enable variations in the tone quality of the instrument. Specifically, the invention contemplates a modification of the mouthpiece for single reed instruments, such as clarinets and saxophones, wherein an independent and interchangeable secondary reed having mounted thereon a wedge is positioned inside the hollow mouthpiece chamber, the secondary reed vibrating sympathetically when the primary reed is placed in vibrating motion during ordinary use of the instrument to which the mouthpiece is attached and the wedge altering the cross-sectional area of the tone chamber of the mouthpiece.
Disclosure Statement
Interchangeable wedge-shaped members have been positioned within the interior of mouthpiece chambers of woodwind instruments in order to change the cross-sectional area of the chamber and thereby modify the tone quality which is produced. Such structures are shown in U.S. Pat. Nos. 2,397,593, issued Apr. 2, 1946, to Brilhart; 3,202,032, issued Aug. 24, 1965, to Strathmann; and 2,530,155, issued Nov. 14, 1950, to DeLuca. U.S. Pat. No. 4,041,827, issued Aug. 16, 1977, to Daglis, discloses a tone enhancing element which is incorporated within the mouthpiece of a reed instrument, the element having two steps projecting into the air flow-through passage of the mouthpiece at a point opposite the opening over which the reed is mounted. U.S. Pat. Nos. 2,224,719, issued Dec. 10, 1940, to Brilhart and 2,499,855, issued Mar. 7, 1950, to Gamble, disclose adjusting the tone quality of woodwind instruments by including means which contact the primary reed in order to alter the tone quality produced by the instrument. Another mouthpiece is disclosed in U.S. Pat. No. 1,583,382, issued May 4, 1926, to Bauer, wherein a single piece of stamped bifurcated metal is secured to the inside surface of the mouthpiece, where functioning depends on a critical position in the mouthpiece of the inserted piece of metal in order to accomplish tone alteration. In U.S. Pat. No. 4,212,223, issued July 15, 1980, to the present inventor, a mouthpiece for a woodwind musical instrument is disclosed which contains a primary reed and a secondary reed positioned within the interior of the mouthpiece and which is positioned substantially parallel to the primary reed. While the inventor's prior patent has proven successful in altering the tonal quality of reed instruments, the present invention provides an interchangeable member which combines a secondary reed with a wedge-shaped member placed thereon to alter the tone quality of the reed instrument. None of the other mentioned patents contains a disclosure of a secondary reed suspended in the instrument mouthpiece tone chamber substantially parallel to the primary reed, nor do any of the patents disclose the interchangeable tone-altering member of the present invention which includes a combination of a sympathetically vibrating secondary reed and a wedge-shaped member placed thereon which alters the cross-sectional area of the tone chamber.
SUMMARY OF THE INVENTION
In accordance with the present invention, a woodwind musical instrument mouthpiece is provided in the interior thereof with an interchangeable tone-altering member comprising a secondary reed which vibrates inside the tone chamber of the mouthpiece for the purpose of adding intensity and character to the tone quality when the mouthpiece is played with an associated appropriate musical instrument and which includes on one end thereof a wedge-shaped member which alters the size of the tone chamber and thereby further changes the tone produced by the instrument. The instruments which are particularly contemplated for modification according to the teachings of the present invention include but are not limited to various types of clarinets and saxophones, such as a B-flat clarient, an alto clarinet, a bass clarinet, and the like; also contemplated are alto saxophones, tenor saxophones, baritone saxophones, soprano saxophones, bass saxophones, and the like. The interchangeable tone-altering element is preferably mounted within the interior of the tone chamber such that the secondary reed is positioned in a plane substantially parallel to the plane of the longitudinal extent of the tone chamber. The wedge-shaped member is positioned on the flat side of the secondary reed facing the primary reed and is positioned on the secondary reed at the end nearest the opening of the mouthpiece. The wedge-shaped member tapers in the direction of the opening of the mouthpiece. The combined tone-altering member is positioned within the interior of the tone chamber and moved therein by a pair of retaining grooves which are formed along the interior surface on opposite sides of the tone chamber. By varying the sizes of the wedge, the interchanging of the combined tone-altering element will thus modify the tone or sound of the instrument and allow the individual artist to produce the varying types of sound which may be required.
Accordingly, it is an object of the present invention to provide a mouthpiece for reed instruments, wherein the mouthpiece is provided with an interchangeable tone-altering member mounted within the mouthpiece for altering the tone produced by the instrument.
Another object of the invention is to provide an interchangeable tone-altering member which can be positioned within the interior of the mouthpiece of a wind instrument, the tone-altering member comprising a secondary reed which vibrates sympathetically within the tone chamber of the musical instrument mouthpiece and a wedge positioned on one end of the secondary reed for altering the cross-sectional area of the tone chamber.
Still another object of the invention is to provide a mouthpiece for a wind instrument with an interchangeable tone-altering member formed of a secondary reed which vibrates sympathetically with the primary reed of the instrument and which further includes a wedge positioned on one end of the secondary reed for altering the cross-sectional area of the tone chamber, the interchangeable member being positioned into and out of the interior of the tone chamber by means of a pair of retaining grooves.
Still yet another object of the invention is to alter the tone quality of a reed instrument by incorporating within the interior of the tone chamber of the instrument an interchangeable tone-altering member which comprises a secondary reed which vibrates sympathetically with the primary reed and a wedge-shaped member which is positioned at one end of the secondary reed and which alters the cross-sectional area of the tone chamber.
These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a mouthpiece for use with a reed instrument and illustrating the placement of the tone-altering member of the present invention within the tone chamber.
FIG. 2 is a longitudinal sectional view of the mouthpiece of FIG. 1 showing the placement of the tone-altering member within the tone chamber, the primary reed and holding device therefor shown in phantom.
FIG. 3 is a transverse sectional view illustrating the placement and retention of the tone-altering member of the present invention within the mouthpiece by means of a pair of retaining grooves.
FIG. 4 is a perspective view illustrating the combined tone-altering member of the present invention.
FIG. 5 is a view of the secondary reed without the wedge and illustrating the pair of mounting flanges.
DETAILED DESCRIPTION OF THE INVENTION
The mouthpiece for single reed instruments is conventionally carved from wood or plastic, or, if made from plastic, can be made by conventional lost wax casting or molding techniques. Although varying somewhat in size, external appearance, and shape, according to the intended instruments with which the mouthpiece is to be used, the general configuration and structure of mouthpiece to be used with various single reed musical instruments is shown in FIGS. 1 and 2, wherein a mouthpiece frame 10 is illustrated, over which a tapered annular ligature 12 slides in order to retain primary reed 14 in contact with the lower surface 16 of mouthpiece 10. Mouthpiece frame 10 is made up of tubular connection 18 for insertion within the upper end of a conventional wind instrument body (not shown), and frame 10 also has an inclined wall 20 against which the musical performer's upper lip rests during operation of the instrument. Thumb screw 22 passes through a through hole in ligature 12, with rotation of thumb screw 22 effecting tightening action of ligature 12 against the lower surface 16 of mouthpiece frame 10 to hold primary reed 14 in place. The construction and operation of ligature 12 is standard and conventional and does not relate to the operation or mounting of the tone-altering member of the present invention.
Referring now to FIG. 2, primary reed 14 can be seen held in place against lower surface 16 of mouthpiece frame 10 by ligature 12. Primary reed 14 is conventionally cut out of elastic reed plates, such as cane, and tapers to primary reed edge 24, which projects somewhat below arcuate end 26 of inclined wall 20 of mouthpiece frame 10, leaving a chink through which the musician blows in order to set tapered edge 24 in vibratory motion in conventional operation of the instrument. Vibrations of primary reed 14 set the entire column of air in the instrument in motion, and reinforcement from waves of air which arise in the interior of the instrument produces an alternation in the pressure of air adjacent to reed 14 sufficiently powerful to make it vibrate sensibly. The tones produced by instrument has a pitch determined by the length of the column of air in the instrument, the acoustic length of which can be altered by opening the side holes located in the body (not shown) of the instrument. The time of vibration of primary reed 14 consists of the time of forward motion, the time of rest, and the time of recoil. When the reed is placed in the mouth, the air pressure on inside surface 28 of reed 14 is equal to the pressure against outside surface 30 of reed 14. As the musician blows through the chink, a suction is created against inside surface 28, drawing edge 24 in the direction of end 26 after the pulse of compressed air exits at the first found point of outlet on the musical instrument, external air then rushes in to restore equilibrium and cause edge 24 of reed 14 to recoil. Cyclic repetition of this process sets the entire column of air within mouthpiece frame 10 and the associated instrument body (not shown) in periodic motion which generates the acoustic tone or sound characteristic of the musical instrument. Accordingly, the air within mouthpiece tone chamber 32 oscillates to form a wave characteristic of the musical instrument with its side holes opened as desired by the musician to generate the desired tone. Positioned within tone chamber 32 is the tone-altering member 34 of the present invention comprising secondary reed 36 and wedge 38. The oscillatory motion of the air within tone chamber 32 sets secondary reed 36 into sympathetic vibration and causes a modification in the tone quality obtained. Similarly, the thickness of wedge 38 alters the cross-sectional area of tone chamber 32 and thus the column of air which is set in motion in tone chamber 32 and thereby further modifies the tone quality obtained from the musical instrument.
The phenomenon of sympathetic resonance is well-known to musicians. When, for example, the strings of two violins are tuned to the same pitch, and one string is bowed, the other will begin to vibrate. Even when the pitch of the primary sounding body is not exactly that of the sympathetically vibrating body, the latter will nevertheless often make sensible sympathetic vibrations, which diminish in amplitude as the difference of pitch increases. Light elastic bodies which offer little resistance can be more easily adapted to vibrate sympathetically to a primary tone than massive elastic bodies. Moreover, sympathetic vibration can also be induced corresponding to the harmonic upper partial tones of the primary body. The mode of transmission from a primary vibrating body to a secondary vibrating body is well-known in the theory of sound, involving principles of wave motion observable in response to periodic changes in air pressure created by mechanical motion. Accordingly, when primary reed 14 begins to vibrate by movement of edge 24 alternately toward and away from end 26 of mouthpiece frame 10, thereby setting in oscillatory motion the air in tone chamber 32 and producing the characteristic combination of proper and harmonic tones which are unique to the particular instrument with which the mouthpiece is associated, sympathetic reed 36 begins to vibrate through the action of the oscillatory motion of the air within tone chamber 32, with end 40 of secondary reed 36 describing vibratory motion in a direction essentially perpendicular to its plane. The addition of a sympathetic reed within the tone chamber of the mouthpiece of a wind instrument is disclosed in U.S. Pat. No. 4,212,223, issued to the present inventor. By incorporating a secondary reed within the tone chamber of the mouthpiece, it was found that the tone quality of the instrument is altered and that greater intensity and character of the tone quality results. Aesthetically speaking, use of the invention adds another dimension to the tone and adds life to the tone. With the use of a secondary reed, not only is the quality of the musical experience enhanced, but the musician is capable of achieving a wider variety of artistic effects, in somewhat the same manner as a musician playing a trumpet or trombone with an added mute or a musician playing a violin or viola when modifying the tone quality with an appropriate muting device. Unlike the various known muting devices, however, a secondary reed does not shade the tone quality toward a more subdued or mellow character, but instead achieves the opposite tone modification, by adding extra intensity, character and life without detracting therefrom.
The present invention is an improvement on the earlier patented secondary reed. In accordance with the present invention and as illustrated in FIGS. 2 and 4, tone-altering member 34 comprises secondary reed 36 and wedge 38 which is built on one end of secondary reed 36 and which is also placed within tone chamber 32. Wedge 38 alters the tone chamber so that it comprises a smaller cross-sectional area, and thereby changes the tone quality of the instrument to a thinner, more piercing type of tone and further increases the volume. The thicker the wedge 38, the louder the tone emanating from the musical instrument will be. As can be seen, wedge 38 is placed on secondary reed 36 so as to face and lie in a plane substantially parallel to primary reed 14. The wedge tapers in a direction from the interior of tone chamber 32 toward end 26 of surface 20.
Tone-altering member 34 can be constructed of the same material as mouthpiece frame 10. Secondary reed 36 and wedge 38 can be made as an integral unit or the two members can be formed separately and bonded together by either a separate bonding agent or fused together if formed from plastic. Accordingly, tone-altering member 34 can be made of metal, wood, cane, or plastic.
Although the invention has been described and illustrated with respect to modification of a single reed mouthpiece, such as that in use with saxophones and clarinets of various types, the concept of the invention can be extended to modify a tone quality of double reed instruments, such as the oboe, bassoon and English horn. Materials of construction for mouthpiece 10 can vary, including the plastic illustrated in the drawings, but also encompassing metal, hard rubber, and the like. Moreover, primary reed 14 can be selected from a plurality of possible construction materials, including plastic, elastic wood, French cane, and the like.
An important feature of the present invention relates to the interchangeability of tone-altering member 34. Accordingly, various sizes and types of second reeds 36 can be associated with wedges 38 of various thicknesses so as to allow the musician to change the tone quality of the instrument by simply interchanging the various tone-altering members 34. Referring to FIGS. 3, 4 and 5 it can be seen that tone-altering member 34 is provided with a pair of mounting flanges 41 and 42 which are formed on opposite sides of reed 36 at the end which supports wedge 38. Flanges 41 and 42 fit within a pair of longitudinal retaining grooves 44 and 46 formed in the interior of mouthpiece 10. Accordingly, simply by placing tone-altering member 34 within tone chamber 32 such that flanges 41 and 42 are retained within grooves 44 and 46, tone-altering member 34 is maintained in place. To remove one particular tone-altering member 34 and replace it with another, one simply inserts a pointed object into hole 50 placed at the outer end of wedge 38 and slides tone-altering member 34 such that flanges 41 and 42 are no longer retained within grooves 44 and 46. It can be seen that primary reed 14 needs to be removed prior to removing tone-altering member 34.
The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
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A mouthpiece for use with single reed woodwind musical instruments, such as saxophones, clarinets, and the like, includes a secondary reed containing a wedge-shaped element built on one end thereof, the secondary reed being contained within the interior of the mouthpiece and interchangeable with other secondary reeds having juxtaposed thereon wedges of various sizes to alter the tone of the instrument. The secondary reed is held in position in the interior of the mouthpiece by a pair of retaining grooves placed in opposite sides of the mouthpiece and which receive opposite side edges of the secondary reed which is positioned into and out of the interior of the mouthpiece by simply sliding the secondary reed within the pair of retaining grooves.
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This application is a divisional of U.S. Ser. No. 09/754,467, filed Jan. 4, 2001, which is hereby incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates broadly to Stirling engines. More particularly, the invention relates to a Stirling engine having a fluid heat exchanger adapted to have improved heat transfer and operate under high pressure and temperature.
2. State of the Art
Frequently heat energy must be exchanged between two or more fluids which do not mix and which may be flowing or stagnant. The heat energy is transferred from the hotter fluid to a separating wall by convection and/or radiation. Heat energy is conducted through the wall from the hot side to the cold side. Heat energy is then transferred from the separating wall to the cooler fluid by convection and/or radiation. The purpose of the heat exchanger may be to raise the temperature of a relatively cool fluid (as a heater) or to lower the temperature of a relatively hot fluid (as a cooler).
Except for radiative only heat exchangers, all heat exchangers have large surfaces where heat energy is absorbed or given off by the surface contacted by the fluids. There are basically three types of fluid heat exchangers for Stirling engines defined by the fluid interfacing configurations. Heat exchangers for Stirling engines may be annular, finned, or tubular, or various combinations of these. Annular heat exchangers consist of concentric tubes with the fluids contained in or between them. The tubes may be cylindrical or of other closed cross sections. One tube separates the fluids and provides the surface area and conductive path required for heat exchange. Finned heat exchangers increase the surface area exposed to one or both fluids by providing finned structures on one or both sides of the wall, which effectively increase the surface area of the wall thus improving heat transfer. Tubular heat exchangers contain one fluid within relatively small diameter tubes that are surrounded by the other fluid. Heat is conducted through the tube wall. Various combinations of these three types may also be used in a heat exchanger. For example, fins may be added to the tubes of an annular heat exchanger to increase the contacted surface area.
Annular (with and without fins) and tubular heat exchangers have been used for Stirling engines. Tubular heat exchangers (with and without fins) have been traditionally used for engines with power outputs greater than 1 kW mechanical. Many small diameter tubes provide large surface area and the small diameters have lower stress at high pressures. Tubular heat exchangers are the most expensive to produce and are susceptible to burnout due to uneven heating and high stresses at the attachment points due to thermal expansion deformation of long tubes.
Often one or more of the fluids may be pressurized to a relatively high level. In such case, the separating wall must structurally resist the difference in pressure between the fluids. For high heat exchanger efficiency, large fluid contacted surfaces and low thermal resistance through the separating wall are desired. Low thermal resistance is achieved by using a thin separating wall, large contact area, and a material with high thermal conductivity. On the other hand, high structural strength to resist deformation by pressure is achieved by using thick walls, small surface areas, and high strength materials. In general materials with high thermal conductivity do not have high strength and high strength materials have low thermal conductivity. Thus, the desired characteristics of heat exchanger designs assuring high thermal efficiency and high strength conflict.
With particular reference to Stirling engines, such engines are typically provided with four heat exchangers: a heater, a regenerator, a cooler, and an exhaust/inlet air preheater. A more detailed explanation of the respective functions of the heat exchangers of Stirling engines can be found in G. Walker in “Stirling Engines”, Clarendon Press, 1980, pp. 124-126, 133-144, and 156-159, which is hereby incorporated by reference herein in its entirety. The above described annular, tubular, and finned heat exchangers, as well as combinations thereof, have all been used in various Stirling engines for heaters and coolers. For example, U.S. Pat. No. 4,671,064, which is hereby incorporated by reference herein in its entirety, describes an annular heat exchanger for a Stirling engine. C. M. Hargreaves in “The Philips Stirling Engine”, Elsevier, 1991, pp. 185-187, describes finned heat exchangers (referred to as “concertina” and “partition” heaters) in Stirling engines.
For maximum efficiency, the Stirling engine working fluid temperature should be as high (as close to the heating fluid temperature) as possible at the heater and as low (as close to the cooling fluid temperature) at the cooler as possible. For maximum power production, the working fluid pressure should be as high as possible. This requires high thermal conductivity of the wall separating the fluids and high strength at the operating temperature. Heating fluid temperature should be as high as the heat exchanger construction material can withstand at the working fluid pressure.
One manner of increasing the pressure-resisting strength of a pressure vessel is to use “orthogonal grillage” about a separating wall; i.e., providing straight internal fins parallel to the cylinder axis combined with disk-like external fins perpendicular to the axis and integral to the separating wall. The straight and disk-like fins cross each other at right angles. “Orthogonal grillage” is described in more detail in J. F. Harvey in “Theory and Design of Modern Pressure Vessels”, 2 nd Ed., Van Norstrand Reinhold, 1974, pp. 120-122, which is hereby incorporated by reference herein in its entirety. However, orthogonal grillage has the disadvantage in that it is complicated and difficult to move a heating fluid around the pressure vessel to permit the heat exchange.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a heat exchanger for heating or cooling a fluid in a high pressure vessel.
It is another object of the invention to provide a heat exchanger which has a relatively high structural integrity.
It is a further object of the invention to provide a heat exchanger through which it is relatively easy to circulate heating fluid.
It is an additional object of the invention to provide a heat exchanger which has a high heat transfer efficiency.
It is also an object of the invention to provide a heat exchanger which is relatively light weight.
It is still another object of the invention to provide a heat exchanger which is relatively inexpensive to manufacture.
It is yet another object of the invention to provide a heat exchanger for a Stirling engine.
In accord with these objects, which will be discussed in detail below, an annular heat exchanger having helical fins is provided. According to preferred aspect of the invention, an outer reinforcing sleeve is provided about the helical fins. The sleeve improves the pressure resisting ability of a thin separating wall (e.g., the heater wall of a Stirling engine) resulting in a high-pressure heat exchanger with high heat transfer efficiency. In addition, the sleeve and helical fins together define fluid passages for the flow of a heating fluid.
The heat exchanger according to the invention has an ability to resist high pressures at high temperatures without excessive or permanent distortion, has an improved heat transfer capability, better reliability, and lower production cost than prior art heat exchangers.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial cut-away side elevation view of a Stirling engine according to the invention;
FIG. 2 enlarged partial cut-away side elevation view of a hot end heat exchanger and heating fluid passages of a Stirling engine according to the invention, revealing heating fluid passages;
FIG. 3 is a section view across line 3 — 3 in FIG. 2;
FIG. 4 is a section view across line 4 — 4 in FIG. 2; and
FIG. 5 an enlarged section through a cylinder wall, and heater wall fins and outer sleeve of the heat exchanger according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, a Stirling engine 10 generally includes a pressure vessel 12 , a hot end heat exchanger (heater) 16 , a cold end heat exchanger (cooler) 18 , a regenerator 20 , a piston 22 , a displacer 24 , and a crank assembly 25 . The pressure vessel 12 defines a working space containing a pressurized working fluid (not shown). The heater 16 (described in detail below) adds heat to the working fluid in the pressure vessel (to increase total working fluid pressure in the system). The cooler 18 removes heat from the working fluid (and decreases total working fluid pressure in the system). The regenerator 20 serves as a thermal storage medium and increases the engine efficiency by reducing energy losses as the working fluid is alternately transferred between the hot and cold ends. The heater 16 is preferably integrated with the regenerator 20 , and both are preferably positioned on top of the cooler 18 .
The working space, mentioned above, is defined as all of the space or internal volume occupied by the working fluid, and includes the fixed internal volumes of the heater 16 , regenerator 20 , and cooler 18 as well as any connecting ducts or passageways. The working space also includes a variable compression space 26 and a variable expansion space 27 . The compression space 26 is the volume contained between the displacer 24 and the piston 22 that varies as the displacer 24 and piston 22 move axially in a cylinder 29 (discussed below) relative to each other. The expansion space 27 is the volume contained between the displacer 24 and a closed hot end of the pressure vessel (end cap 38 , discussed below).
The axial position of the displacer 24 in the cylinder 29 is always ahead of the position of the piston 22 with respect to time. Oscillating motion of the displacer 24 transfers or displaces working fluid alternately between the compression space 26 and expansion space 27 . Working fluid flow to and from the compression space 26 and expansion space 27 must flow through the heater 16 , regenerator 20 and cooler 18 .
In general, the working fluid pressure in the total working space is uniform at any instant in time. When working fluid flow is from the regenerator 20 , through the heater 16 , and into the expansion space 27 , working fluid temperature and pressure increase and the piston 22 is forced out by having a higher pressure on the working fluid side than on the opposite side. When working fluid flow is from the regenerator 20 , through the cooler 18 , and into the compression space 26 , working fluid temperature and pressure decrease and the piston 22 returns. Thus, the oscillating motion of the displacer 24 creates an oscillating pressure wave in the working fluid that moves the piston 22 in and out. The piston, acting on crank assembly 25 , moves the displacer 24 to provide the pressure wave and also produces mechanical energy at an output shaft 28 .
Before explaining the heater 16 of the invention, it is helpful to more fully understand particular elements of the pressure vessel 12 containing the working fluid. Referring to FIGS. 2 through 5, the pressure vessel 12 includes the cylinder 29 , a tubular wall 30 about the cylinder, preferably axial internal fins 32 between the cylinder 29 and the wall 30 , axial flow fluid passages 34 bounded by the cylinder 29 , wall 30 , and internal fins 32 between the cylinder and the wall, a transition cone 36 , and an end cap 38 . At the location of the transition cone 36 and above the end of the cylinder, radial ports 40 at the ends of the fluid passages 34 permit the working fluid to move alternately to and from the expansion space 27 and the axial flow fluid passages 34 . In the preferred configuration, the cylinder ends below the ends of the passageways 40 , as shown by the cross-hatching in FIG. 4 . Alternatively, the cylinder 29 may extend higher and have ports cut into it that correspond to the ends of passages 34 . The pressure vessel also includes a flange 39 which mates with the cooler 18 and provides a sealed annular opening at the bottom of the regenerator 20 for passage of the working fluid between the regenerator and the cooler.
The function of the heater 16 is to add heat to the pressurized working fluid within the axial fluid passages 34 . The heater 16 is an annular heat exchanger which, according to a first preferred aspect of the invention, has external helical fins 42 integral with the exterior of wall 30 and axial internal fins 32 integral with the interior of wall 30 . The helical fins 42 preferably taper away from wall 30 , but may also have uniform thickness. An exemplar size for the fins includes a width of 0.125″ at the root 42 a of the fin (against the wall 30 ), a width of 0.06″ at the tip 42 b , and a height 42 c of 0.5″ (FIG. 5 ), though fins of other sizes may be used. It will be appreciated that because in FIG. 5 the fins are sectioned at an oblique angle, the exemplar preferred relative dimensions of the fins are distorted. An exemplar preferred lay angle for the helical fins 42 is one revolution every 3.5 inches about a 3.5 inch diameter wall 30 . The helical fins 42 increase heat transfer across the wall 30 by effectively increasing the surface area of the wall that can be wetted (contacted) by the heating fluid. It will be appreciated that helical fins 42 are longer than either of annular fins or longitudinal fins, and therefore provide a relatively larger surface over which heat transfer between the heating fluid and the working fluid can occur. Longer fins 42 imply longer passages 48 and therefore more time for heat transfer with the heating fluid at any given heating fluid velocity. Furthermore, the helical fins 42 add substantial structural integrity to the heat exchanger.
According to a second preferred aspect of the invention, an outer tubular reinforcing sleeve 44 is attached to the outer edges of the helical fins 42 . The resulting unified construction of the wall 30 , axial fins 32 , helical fins 42 , and sleeve 44 provides a composite pressure vessel wall with an effective thickness much greater than the wall 30 alone; in effect, providing a wall with an effective wall strength approximating the combined material of the sleeve 44 , the helical fins 42 , axial fins 32 , and the wall 30 , while retaining the superior heat transfer performance of a single wall of the thickness of wall 30 . As such, the sleeve 44 greatly improves the pressure resisting ability of the wall 30 resulting in a high-pressure and temperature heat exchanger with high heat transfer efficiency.
The sleeve 44 , transition cone 36 , lower portion of end cap 38 , and wall 30 define a plenum 46 (FIG. 2) which distributes heating fluid to numerous inlets of the relatively long helical fluid passages 48 defined between the sleeve 44 , the helical fins 42 , and the wall 30 . The number of helical fins 42 and passages 48 are optimized according to a particular application, and is based on factors such as fluid nature (liquid, gas, or a combination), fluid velocity, temperature, viscosity, etc. The thermal and structural properties of the wall 30 , helical fins 42 , axial fins 32 , and sleeve 44 determine the optimum dimension of those components. A preferred material for both of the helical fins and sleeve is a high temperature, high strength metal or alloy, such as stainless steel or a superalloy including Inconel® NiCrFe alloy, Allvac Waspaloy® (UNS-N07001), Rene® 41, etc.
The sleeve 44 is preferably permanently bonded to the ends of the helical fins 42 by welding, casting, brazing, or some other permanent attachment process. The wall 30 , axial fins 32 , and helical fins 42 are also preferably a unitary construction. The cylinder 29 is optionally permanently bonded to the end of the axial fins 32 by welding or brazing to increase the pressure resisting strength of the vessel.
The heater 16 also includes an insulating barrier 54 , an exhaust cylinder 56 , and an insulating wall 58 . The insulating barrier 54 deflects the heating fluid leaving the helical passages 48 at the bottom of the heater and protects the flange 39 and other engine components from heat. The exhaust cylinder 56 forms an exhaust passage 60 through which the heating fluid exhausts after passing through the helical passages 48 . The exhaust cylinder can be insulated or non-insulated. Once heating fluid is exhausted, it can be directed to another location for use in preheating incoming fluid at 64 (FIG. 1) or other purposes needing heated fluid. The insulating wall 58 surrounds the sleeve 44 and insulates the sleeve from the relatively cooler heating fluid in the exhaust passage 60 , thus maintaining a relatively high temperature at the sleeve.
The heater 16 is less expensive to produce than the tubular heat exchangers of the prior art, has increased surface area over traditional annular heat exchangers of the prior art, and does not have the thermal expansion and uneven heating problems associated with tubular heat exchangers.
In operation, heated fluid is created (e.g., as combustion gas) at 66 (FIG. 1 ). The heated fluid enters the system, surrounds the cap 38 (thereby heating the cap), and enters the plenum 46 of the heater 16 . Because the net heat flow in the structure composed of the sleeve 44 , helical fins 42 , axial fins 32 , and the wall 30 is from the fins 32 into the working fluid in passage 34 , there is a temperature gradient created where the temperature of the sleeve 44 is higher than the temperature of the wall 30 . As a result, there is heat transfer from the sleeve 44 and fins 42 to the wall 30 to heat the working fluid in the axial passages 34 defined by the axial fins 32 .
The work output per revolution and efficiency of a Stirling engine are directly related to the high working fluid pressure and the temperature differential obtained. In view thereof, it will be appreciated that the ability of the heat exchanger 16 to operate under extremely high working fluid pressures (e.g., 150 psi-450 psi or more) and large temperature differentials (e.g., 1000° F. or more) permit the realization of a high efficiency heat exchanger and enable a relatively high power output and particularly efficient engine. The heat exchanger of the invention can be used anywhere a high efficiency high temperature heat exchanger operating with high-pressure fluid is needed.
There have been described and illustrated herein a Stirling engine and particularly a heat exchanger suitable for a Stirling engine. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while a both helical fins and an outer reinforcing sleeve have been disclosed on the heat exchanger, it is believed that each component provides advantage over prior art heat exchanger, and each component may be used alone without the other. As such, the external fins may be radial or axial in shape with a reinforcing sleeve thereabout. Regardless of which shape, it is preferable that the angle between the internal and external fins should be relatively large (e.g., 70°-110°) such that the strengthening advantage of orthogonal grillage is maintained. In addition, if desired, bumps, wall variations and/or inserts can be added to the helical passages or axial passages to induce turbulence in the fluid flows and/or increase the surface area available for heat transfer. Also, while a particular heating fluid (combustion gas) has been disclosed, it will be appreciated that other heating fluids, in gas and liquid form, may be used as well. Furthermore, while the axial internal fins are described as defining axial flow passages, it will be appreciated that such fins may be radial or helical in shape, as this may be an advantage in lengthening the working fluid flow path to give more time for heat exchange at higher fluid velocities. In addition, the heating fluid direction may be reversed with flow through the helical fluid passages in the opposite direction. Flow may also be reversing or oscillating, if desired. Moreover, it will appreciated that the heat exchanger can be configured as a Stirling engine cooler. When used as a cooler, the sleeve and helical fins are preferably made from aluminum. Also, while particular materials have been disclosed, it will be appreciated that other suitable materials may be used. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.
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A Stirling engine includes a heat exchanger having helical and axial fins forming an orthogonal grillage on either side of a pressure resisting wall, and an outer reinforcing sleeve about the helical fins. The sleeve improves the pressure resisting ability of a thin separating wall between a pressurized fluid and an outside working environment, resulting in a high-pressure and temperature heat exchanger with high heat transfer efficiency. In addition, the sleeve and helical fins together define fluid passages for the flow of heating fluid. The heat exchanger according to the invention has the ability to resist high pressures at high temperatures without excessive distortion, has improved heat transfer capability, better reliability, and lower production cost than prior art heat exchangers.
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FIELD OF THE INVENTION
[0001] The present invention relates to methods, kits and assay system for detecting drug-resistant Mycobacterium tuberculosis from samples of suspected patient.
BACKGROUND OF THE INVENTION
[0002] Tuberculosis (TB) is the leading infectious killer of youth and adults and the first most common infectious disease worldwide. One third of the world's population is currently infected and 20 million of those infected are active cases; TB will kill 30 million people this decade. More than 50 million people may already be infected with multidrug-resistant (MDR) strains of TB. Prior to MDR tuberculosis, the success rate of drug combination treatment was greater than 90%, even in AIDS patients. MDR tuberculosis, however, is not only highly infectious but also essentially incurable with a mortality of 50%.
[0003] Tuberculosis is caused by infection with Mycobacterium tuberculosis , a bacillus bacterium. It is spread by aerosol droplets and causes irreversible lung destruction. Recently, because of complications due to multidrug-resistant strains, the number and combination of antibiotics administered must be individually tailored depending on the strain the patient is harboring. In general, manifest disease with an MDR strain of Mycobacterium tuberculosis —a strain resistant to both isoniazid and rifampin, and possibly to additional drugs—has a poor clinical outcome since efficient therapeutic strategies are still lacking.
[0004] Initially, antimicrobial susceptibility testing of Mycobacterium tuberculosis is carried out with a primary set of drugs, consisting of the front-line drugs isoniazid, rifampin, ethambutol, pyrazinamide, and, optionally, streptomycin. If resistance to one or several of these drugs is detected, it is common practice to test an extended spectrum of antimicrobial compounds.
[0005] For quite some time three different growth-based laboratory methods have been accepted for determining antimicrobial susceptibility of Mycobacterium tuberculosis : (1) the resistance ratio method, (2) the absolute concentration method, and (3) the proportion method. Most laboratories in the Western hemisphere utilize a modified proportion method on solid medium. For most of the major antituberculous agents, this technique defines resistance of Mycobacterium tuberculosis as a percentage of resistant organisms larger than 1 percent in a given population of bacilli.
[0006] Because antimicrobial susceptibility testing on solid media requires visible growth of the organisms (which requires three weeks of incubation), testing is preferentially done in liquid media today.
[0007] In the last decade antimicrobial susceptibility testing has become a dynamic field spawning many new technologies. They all comply with the standard set by the Centers for Disease Control and Prevention that susceptibility testing results for Mycobacterium tuberculosis have to be available within 28 days of the time the specimen arrives in the laboratory (Bird B R. et al, J Clin Microbiol 996; 34:554-559.).
[0008] An increasing number of approaches assess drug susceptibility by identifying alternative markers of drug-resistant metabolic activities. Among those are colorimetry, flow cytometry (Norden, M A. et al, J Clin Microbiol 1995; 33:1231-1237), bioluminescence assay of mycobacterial adenosine triphosphate (Nilsson, L E et al, Antimicrob Agents Chemother 1988; 32:1208-1212.), and quantitation of mycobacterial antigens (Drowart, A. et al., Int J Tuberc Lung Dis 1997; 1:284-288.). Mycobacteriophage-based methods, for example, with luciferase reporter phages or PhaB phages, appear to be promising as well (Jacobs, W Jr et al., Science 1993; 260:819-822). However, the complexities of these technologies and high cost have largely hampered their wider application in the clinical mycobacteriology laboratory.
[0009] Molecular biology as a tool to detect resistant TB. Mycobacterium tuberculosis resistance to drugs always results from mutations. These mutations are either deleterious for the bacterial cell or, conversely, alter the structure of a protein targeted by a drug without compromising the protein's function for the microorganism. In Mycobacterium tuberculosis these mutations appear to be confined to chromosomal DNA and do not involve mobile genetic elements (such as plasmids).
[0010] In particular, DNA sequencing, but also other techniques such as gel electrophoresis (single-stranded conformation polymorphism [SSCP]-PCR, dideoxy fingerprinting) and hybridization on solid phase (line probe assay, DNA chip technology) or on liquid phase (heteroduplex analysis, mismatch cleaving assay, molecular beacon) can identify those subtle mutations.
[0011] Resistance to rifampin, the most important component of current treatment regimens, is associated with a short core region consisting of 27 amino acids in the rpoB gene, which codes for the β subunit of RNA polymerase (Telenti, A. et al, Lancet 1993; 341:647-650). The ethambutol resistance-determining region (ERDR) has been proposed as a mutational hot spot in the embB gene, whereas the situation with pyrazinamide resistance is less clear. Resistance to isoniazid appears to be the complex result of single or multiple mutations in the katG, inhA, oxyR-ahpC, and/or kasA gene(s) (Heym, B. et al, Lancet 1994; 344:293-298.). Similarly, mutations in the rpsL and/or rrs gene(s) correlate with resistance in approximately 80 percent of streptomycin-resistant strains (Böttger, E C. Trends Microbiol 1994; 2:416-421).
[0012] In light of the worsening global TB epidemic and the extreme vulnerability of HIV-infected individuals to TB, rapid and reliable antimicrobial susceptibility testing in the laboratory is paramount for proper management of patients, particularly those with MDR TB.
[0013] Given the above, current available assay cannot quickly and completely detect drug-resistant Mycobacterium tuberculosis . It requires a quick assay with high specificity and sensitivity to detect drug-resistant Mycobacterium tuberculosis from available samples, especially from sputum of suspected patients.
SUMMARY OF THE INVENTION
[0014] The present invention relates to methods, kits and assay system for detecting drug-resistant Mycobacterium tuberculosis from the samples of suspected patient.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 shows the outline of the detection method of the invention.
[0016] FIG. 2 shows the result of identifying drug-sensitive Mycobacterium tuberculosis using probe P 1 , P 2 , P 3 , P 4 and P 5 .
[0017] FIG. 3 shows the differentiation of drug-sensitive Mycobacterium tuberculosis strains W 191 and W 192 from drug-resistant Mycobacterium tuberculosis Y 94 , P 80 and Y 194 using probe P 1 , P 2 , P 3 , P 4 and P 5 .
[0018] FIG. 4 shows the differentiation of drug-sensitive M. tuberculosis strains W 191 and W 192 from drug-resistant Mycobacterium tuberculosis Y 94 , P 80 and Y 194 using probe P 1 , P 2 and P 5 .
[0019] FIG. 5 shows the differentiation of drug-sensitive Mycobacterium tuberculosis strains F 144 w and E 74 w from drug-resistant Mycobacterium tuberculosis Z 111 R using probe P 1 , P 2 and P 5
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] The present invention provides a method for detecting drug-resistant Mycobacterium tuberculosis DNA comprising:
[0000] (a) hybridizing the drug-resistant Mycobacterium tuberculosis cDNA with drug-resistant Mycobacterium tuberculosis -specific probes in hybridization tube;
(b) adding blocking solution into the tubes;
(c) adding avidin enzyme complex or streptavidin enzyme complex into the tubes;
(d) performing washing reaction to remove interfering material;
(e) adding substrate of enzyme; and
(f) detecting the luminescent or color change adding substrate of enzyme.
[0021] The probe may be linked to magnetic bead. In the method of the invention, it further comprises transferring hybridization tubes to magnetic wells for washing between steps (a) and (b).
[0022] In general, any biological sample such as CSF, serum, blood, sputum, pleural effusion, throat swab and stools can be used in the clinical tests. The preferred samples for drug-resistant Mycobacterium tuberculosis are from CSF, serum, blood, sputum, pleural effusion, throat swab. The method of the invention is shown in FIG. 1 .
[0023] Polymerase Chain Reaction (PCR) PCR is described in Saiki et al. (1985), Science, 230 1350. PCR consists of repeated cycles of DNA polymerase generated primer extension reactions. The target DNA is heat denatured and two oligonucleotides, which bracket the target sequence on opposite strands of the DNA to be amplified, are hybridized. These oligonucleotides become primers for use with DNA polymerase. The DNA is copied by primer extension to make a second copy of both strands. By repeating the cycle of heat denaturation, primer hybridization and extension, the target DNA can be amplified a million fold or more in about two to four hours. PCR is a molecular biology tool that must be used in conjunction with a detection technique to determine the results of amplification. In the present invention, biotinylated primer pairs are used in the PCR amplification.
[0024] As used herein, a “probe” is a substance, e.g., a molecule, which can be specifically recognized by a particular target. Generally, probes will be linked to solid support to facilitate the separation of DNA. In the invention, the probes linked to magnetic beads (MagProbe) are preferred. At least one of the sequence of the probe in MagProbe can be selected from the group consisting of:
[0000]
P1:
1.
5′-CAGCCAGCTGAGCCAATTCAT-3′
(SEQ ID NO:1)
2.
5′-CAGCCAGCTGAGCCAATTCATGGAC-3′
(SEQ ID NO:2)
3.
5′-CAGCCAGCTGAGCCAATTCATGGA-3′
(SEQ ID NO:3)
4.
5′-CAGCCAGCTGAGCCAATTCATGG-3′
(SEQ ID NO:4)
5.
5′-CAGCCAGCTGAGCCAATTCATG-3′
(SEQ ID NO:5)
6.
5′-CAGCCAGCTGAGCCAATTC-3′
(SEQ ID NO:6)
7.
5′-CAGCCAGCTGAGCCAATTCA-3′
(SEQ ID NO:7)
8.
5′-AGCCAGCTGAGCCAATTCATGG-3′
(SEQ ID NO:8)
9.
5′-GCCAGCTGAGCCAATTCATGGA-3′
(SEQ ID NO:9)
10.
5′-GCCAGCTGAGCCAATTCCATG-3′
(SEQ ID NO:10)
P2:
1.
5′-TTCATGGACCAGAACAACCCGCT -3′
(SEQ ID NO:11)
2.
5′-TTCATGGACCAGAACAACCCGC -3′
(SEQ ID NO:12)
3.
5′-TTCATGGACCAGAACAACCCG -3′
(SEQ ID NO:13)
4.
5′-TTCATGGACCAGAACAACCC -3′
(SEQ ID NO:14)
5.
5′-TTCATGGACCAGAACAACC -3′
(SEQ ID NO:15)
6.
5′-ATTCATGGACCAGAACAACCCGC -3′
(SEQ ID NO:16)
7.
5′-AATTCATGGACCAGAACAACCCG -3′
(SEQ ID NO:17)
8.
5′-CAATTCATGGACCAGAACAACCC -3′
(SEQ ID NO:18)
9.
5′-CCAATTCATGGACCAGAACAACC -3′
(SEQ ID NO:19)
10.
5′-CAATTCATGGACCAGAACAAC -3′
(SEQ ID NO:20)
11.
5′-AATTCATGGACCAGAACAACCCGCT -3′
(SEQ ID NO:21)
P5:
1.
5′-CGACTGTCGGCGCTGGGGC-3′
(SEQ ID NO:22)
2.
5′-CGACTGTCGGCGCTGGGGCC-3′
(SEQ ID NO:23)
3.
5′-CGACTGTCGGCGCTGGGGCCC-3′
(SEQ ID NO:24)
4.
5′-CGACTGTCGGCGCTGGGGCCCG-3′
(SEQ ID NO:25)
5.
5′-CGACTGTCGGCGCTGGGGCCCGG-3′
(SEQ ID NO:26)
6.
5′-CGACTGTCGGCGCTGGGGCCCGGC-3′
(SEQ ID NO:27)
7.
5′-CCGACTGTCGGCGCTGGGGC-3′
(SEQ ID NO:28)
8.
5′-GCCGACTGTCGGCGCTGGGGC-3′
(SEQ ID NO:29)
9.
5′-CGCCGACTGTCGGCGCTGGGGC-3′
(SEQ ID NO:30)
10.
5′-GCGCCGACTGTCGGCGCTGGGGC-3′
(SEQ ID NO:31)
11.
5′-AGCGCCGACTGTCGGCGCTGGGGC-3′
(SEQ ID NO:32)
12.
5′-GACTGTCGGCGCTGGGGCC-3′
(SEQ ID NO:33)
13.
5′-ACTGTCGGCGCTGGGGCCC-3′
(SEQ ID NO:34)
14.
5′-CTGTCGGCGCTGGGGCCCG-3′
(SEQ ID NO:35)
15.
5′-CCGACTGTCGGCGCTGGGG-3′
(SEQ ID NO:36)
16.
5′-GCCGACTGTCGGCGCTGGG-3′
(SEQ ID NO:37)
17.
5′-CGCCGACTGTCGGCGCTGGG-3′
(SEQ ID NO:38)
[0025] The oligomer probes described by SEQ ID NOs. 1 to 38 were constructed to hybridize with a specific DNA sequence of drug-resistant Mycobacterium tuberculosis.
[0026] Detectable labels suitable for use in the present invention include any composition detectable by spectroscopic, photochemical, biochemical, immunochemical, electrical, optical or chemical means. Useful labels in the present invention include biotin for combining with labeled streptavidin conjugate, magnetic beads (e.g., Dynabeads™), fluorescent dyes (e.g., fluorescein, texas red, rhodamine, green fluorescent protein, and the like), radiolabels (e.g., .H3, I125, .S35, .C14, or P32), enzymes (e.g., horse radish peroxidase, alkaline phosphatase and others commonly used in an ELISA), and calorimetric labels such as colloidal gold or colored glass or plastic (e.g., polystyrene, polypropylene, latex, etc.) beads. Patents teaching the use of such labels include U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345; 4,277,437; 4,275,149; and 4,366,241.
[0027] The preferred embodiment of the label is biotin. When biotin is employed, it is detected by avidin, streptavidin or the like, which is conjugated to a detectable marker, such as an enzyme (e.g., horseradish peroxidase). Enzyme conjugates are commercially available from, for example, Vector Laboratories (Burlingame, Calif.). Steptavidin binds with high affinity to biotin, unbound streptavidin is washed away, and the presence of horseradish peroxidase enzyme is then detected using a luminescence-emission substrate in the presence of peroxide and appropriate buffers. The product may be detected using a Berthold Luminometer (Pforzheim, Germany).
[0028] Means of detecting such labels are well known to those of skill in the art. Thus, for example, radiolabels may be detected using photographic film or scintillation counters, fluorescent markers may be detected using a photodetector to detect emitted light. Enzymatic labels are typically detected by providing the enzyme with a substrate and detecting the reaction product produced by the action of the enzyme on the substrate, and colorimetric labels are detected by simply visualizing the colored label.
[0029] An extensive guide to the hybridization of nucleic acids is found in Tijssen, Laboratory Techniques in Biochemistry and Molecular Biology—Hybridization with Nucleic Acid Probes, Part I, Chapter 2 “Overview of principles of hybridization and the strategy of nucleic acid probe assays,” Elsevier, N.Y., (1993). Stringency can be controlled by changing temperature, salt concentration, the presence of organic compounds, such as formamide or DMSO, or all of these. The effects of changing these parameters are well known in the art. Changes in the temperature are generally a preferred means of controlling stringency for convenience, ease of control, and reversibility.
[0030] The present invention also provides a diagnostic kit for detecting drug-resistant Mycobacterium tuberculosis cDNA comprising:
[0000] (a) a probe linked to magnetic bead;
(b) bioactive primers;
(c) avidin enzyme complex or streptavidin enzyme complex; and
(d) enzyme substrate.
wherein the probe is selected from the group consisting of
[0000]
5′-CAGCCAGCTGAGCCAATTCAT-3′,
(SEQ ID NO:1)
5′-CAGCCAGCTGAGCCAATTCATGGAC-3′,
(SEQ ID NO:2)
5′-CAGCCAGCTGAGCCAATTCATGGA-3′,
(SEQ ID NO:3)
5′-CAGCCAGCTGAGCCAATTCATGG-3′,
(SEQ ID NO:4)
5′-CAGCCAGCTGAGCCAATTCATG-3′,
(SEQ ID NO:5)
5′-CAGCCAGCTGAGCCAATTC-3′,
(SEQ ID NO:6)
5′-CAGCCAGCTGAGCCAATTCA-3′,
(SEQ ID NO:7)
5′-AGCCAGCTGAGCCAATTCATGG-3′,
(SEQ ID NO:8)
5′-GCCAGCTGAGCCAATTCATGGA-3′,
(SEQ ID NO:9)
5′-GCCAGCTGAGCCAATTCCATG-3′,
(SEQ ID NO:10)
5′-TTCATGGACCAGAACAACCCGCT -3′,
(SEQ ID NO:11)
5′-TTCATGGACCAGAACAACCCGC -3′,
(SEQ ID NO:12)
5′-TTCATGGACCAGAACAACCCG -3′,
(SEQ ID NO:13)
5′-TTCATGGACCAGAACAACCC -3′,
(SEQ ID NO:14)
5′-TTCATGGACCAGAACAACC -3′,
(SEQ ID NO:15)
5′-ATTCATGGACCAGAACAACCCGC -3′,
(SEQ ID NO:16)
5′-AATTCATGGACCAGAACAACCCG -3′,
(SEQ ID NO:17)
5′-CAATTCATGGACCAGAACAACCC -3′,
(SEQ ID NO:18)
5′-CCAATTCATGGACCAGAACAACC -3′,
(SEQ ID NO:19)
5′-CAATTCATGGACCAGAACAAC -3′,
(SEQ ID NO:20)
5′-AATTCATGGACCAGAACAACCCGCT -3′,
(SEQ ID NO:21)
5′-CGACTGTCGGCGCTGGGGC-3′,
(SEQ ID NO:22)
5′-CGACTGTCGGCGCTGGGGCC-3′,
(SEQ ID NO:23)
5′-CGACTGTCGGCGCTGGGGCCC-3′,
(SEQ ID NO:24)
5′-CGACTGTCGGCGCTGGGGCCCG-3′,
(SEQ ID NO:25)
5′-CGACTGTCGGCGCTGGGGCCCGG-3′,
(SEQ ID NO:26)
5′-CGACTGTCGGCGCTGGGGCCCGGC-3′,
(SEQ ID NO:27)
5′-CCGACTGTCGGCGCTGGGGC-3′,
(SEQ ID NO:28)
5′-GCCGACTGTCGGCGCTGGGGC-3′,
(SEQ ID NO:29)
5′-CGCCGACTGTCGGCGCTGGGGC-3′,
(SEQ ID NO:30)
5′-GCGCCGACTGTCGGCGCTGGGGC-3′,
(SEQ ID NO:31)
5′-AGCGCCGACTGTCGGCGCTGGGGC-3′,
(SEQ ID NO:32)
5′-GACTGTCGGCGCTGGGGCC-3′,
(SEQ ID NO:33)
5′-ACTGTCGGCGCTGGGGCCC-3′,
(SEQ ID NO:34)
5′-CTGTCGGCGCTGGGGCCCG-3′,
(SEQ ID NO:35)
5′-CCGACTGTCGGCGCTGGGG-3′,
(SEQ ID NO:36)
5′-GCCGACTGTCGGCGCTGGG-3′,
(SEQ ID NO:37)
5′-CGCCGACTGTCGGCGCTGGG-3′.
(SEQ ID NO:38)
[0031] In the kit, the bioactive primers are made by reacting DNA labeling reagent with the primers. The DNA labeling reagent is one reagent labeling DNA. The preferred reagent is not limited but the compound having the formula:
[0000] Fu-BE-D
[0000] wherein Fu represents a furocoumarin derivative selected from the group consisting of angelicin derivatives and psoralen derivatives; wherein BE represents none or a binding enhancer selected from the group consisting of C 4-12 alkyl, alkyenyl, polyalkylamine and polyethylene glycol; and wherein D represents a detectable group selected from the group consisting of: biotin, fluorescence, acridinium ester and acridinium-9-carboxamide. The most preferred DNA labeling reagent is 9-(4″-(Aminomethyl)-4′,5″-Dimethyl-angelicin) acridinium carboxamide.
[0032] An assay system for detecting microorganisms, the system comprising:
[0000] (i) diagnostic kit for detecting drug-resistant Mycobacterium tuberculosis cDNA comprising:
[0033] (a) a probe linked to magnetic bead;
[0034] (b) bioactive primers;
[0035] (c) avidin enzyme complex or streptavidin enzyme complex; and
[0036] (d) enzyme substrate
[0000] wherein the probe is selected from the group consisting of
[0000] 5′-CAGCCAGCTGAGCCAATTCAT-3′, (SEQ ID NO:1) 5′-CAGCCAGCTGAGCCAATTCATGGAC-3′, (SEQ ID NO:2) 5′-CAGCCAGCTGAGCCAATTCATGGA-3′, (SEQ ID NO:3) 5′-CAGCCAGCTGAGCCAATTCATGG-3′, (SEQ ID NO:4) 5′-CAGCCAGCTGAGCCAATTCATG-3′, (SEQ ID NO:5) 5′-CAGCCAGCTGAGCCAATTC-3′, (SEQ ID NO:6) 5′-CAGCCAGCTGAGCCAATTCA-3′, (SEQ ID NO:7) 5′-AGCCAGCTGAGCCAATTCATGG-3′, (SEQ ID NO:8) 5′-GCCAGCTGAGCCAATTCATGGA-3′, (SEQ ID NO:9) 5′-GCCAGCTGAGCCAATTCCATG-3′, (SEQ ID NO:10) 5′-TTCATGGACCAGAACAACCCGCT -3′, (SEQ ID NO:11) 5′-TTCATGGACCAGAACAACCCGC -3′, (SEQ ID NO:12) 5′-TTCATGGACCAGAACAACCCG -3′, (SEQ ID NO:13) 5′-TTCATGGACCAGAACAACCC -3′, (SEQ ID NO:14) 5′-TTCATGGACCAGAACAACC -3′, (SEQ ID NO:15) 5′-ATTCATGGACCAGAACAACCCGC -3′, (SEQ ID NO:16) 5′-AATTCATGGACCAGAACAACCCG -3′, (SEQ ID NO:17) 5′-CAATTCATGGACCAGAACAACCC -3′, (SEQ ID NO:18) 5′-CCAATTCATGGACCAGAACAACC -3′, (SEQ ID NO:19) 5′-CAATTCATGGACCAGAACAAC -3′, (SEQ ID NO:20) 5′-AATTCATGGACCAGAACAACCCGCT -3′, (SEQ ID NO:21) 5′-CGACTGTCGGCGCTGGGGC-3′, (SEQ ID NO:22) 5′-CGACTGTCGGCGCTGGGGCC-3′, (SEQ ID NO:23) 5′-CGACTGTCGGCGCTGGGGCCC-3′, (SEQ ID NO:24) 5′-CGACTGTCGGCGCTGGGGCCCG-3′, (SEQ ID NO:25) 5′-CGACTGTCGGCGCTGGGGCCCGG-3′, (SEQ ID NO:26) 5′-CGACTGTCGGCGCTGGGGCCCGGC-3′, (SEQ ID NO:27) 5′-CCGACTGTCGGCGCTGGGGC-3′, (SEQ ID NO:28) 5′-GCCGACTGTCGGCGCTGGGGC-3′, (SEQ ID NO:29) 5′-CGCCGACTGTCGGCGCTGGGGC-3′, (SEQ ID NO:30) 5′-GCGCCGACTGTCGGCGCTGGGGC-3′, (SEQ ID NO:31) 5′-AGCGCCGACTGTCGGCGCTGGGGC-3′, (SEQ ID NO:32) 5′-GACTGTCGGCGCTGGGGCC-3′, (SEQ ID NO:33) 5′-ACTGTCGGCGCTGGGGCCC-3′, (SEQ ID NO:34) 5′-CTGTCGGCGCTGGGGCCCG-3′, (SEQ ID NO:35) 5′-CCGACTGTCGGCGCTGGGG-3′, (SEQ ID NO:36) 5′-GCCGACTGTCGGCGCTGGG-3′, (SEQ ID NO:37) 5′-CGCCGACTGTCGGCGCTGGG-3′. (SEQ ID NO:38)
(ii) an apparatus for performing the dissociation of nucleic acid double strands, hybridization, washing, the separation of magnetic beads and thermal control in the same apparatus, comprising:
[0037] (a) the means for fitting reaction containers;
[0038] (b) the means for controlling the temperature of the containers; and
[0039] (c) the means for controlling the magnetic force of the containers,
[0000] wherein the means for controlling the temperature of the containers are connected to the means for fitting reaction containers, and the means for controlling the magnetic force of the containers are connected to the means for fitting reaction containers;
(iii) a magnetic rack to bind the magnetic bead on the wall of the containers; and
(iv) a detector.
[0040] In the assay system of the invention, the kit further comprises hybridization buffer, washing buffer and blocking buffer. These buffers are easily purchased from commercial products such as those of Pierce, Biolab, Qiagen etc. In general, the assay system of the invention can reduce the whole process of drug-resistant Mycobacterium tuberculosis detection to less than 5 hours.
Definitions and Terms
[0041] Unless defined otherwise, all scientific and technical terms used herein have the same meaning as commonly understood by those skilled in the relevant art. General definitions are provided, for example, in Dictionary of Microbiology and Molecular Biology, 2nd ed. (Singleton et al., 1994, John Wiley & Sons, New York, N.Y.) or The Harper Collins Dictionary of Biology (Hale & Marham, 1991, Harper Perennial, New York, N.Y.). Unless mentioned otherwise, the techniques employed or contemplated herein are well known standard methods in the art.
[0042] Units, prefixes, and symbols are denoted in their System International de Unites (SI) accepted form. Numeric ranges are inclusive of the numbers defining the range. Unless otherwise indicated, nucleic acids are written left to right in 5′ to 3′ orientation. The headings provided herein are not limitations of the various aspects or embodiments of the invention, which can be had by reference to the specification as a whole. Accordingly, the terms defined immediately below are more fully defined by reference to the specification in its entirety.
[0043] By “biological sample” is meant any tissue or material derived from a living or dead human which may contain M Mycobacterium tuberculosis nucleic acid. Samples include, for example, CSF, serum, blood, sputum, pleural effusion, throat swab and stools, respiratory tissue or exudates, plasma, cervical swab samples, biopsy tissue, gastrointestinal tissue, urine, feces, semen or other body fluids, tissues or materials. Samples also include bacterial cultures (from liquid or solid media) and environmental samples. A biological sample may be treated to physically disrupt tissue or cell structure, thus releasing intracellular components into a solution which may contain enzymes, buffers, salts, detergents and the like which are used to prepare the sample for analysis.
[0044] By “nucleic acid” is meant a multimeric compound comprising nucleosides or nucleoside analogs which have nitrogenous heterocyclic bases, or base analogs, where the nucleosides are covalently linked via a backbone structure to form a polynucleotide. Conventional RNA, DNA, and analogs of RNA and DNA are included in this term. A nucleic acid backbone may comprise a variety of known linkages known, including one or more of sugar-phosphodiester linkages, peptide-nucleic acid bonds (“peptide nucleic acids”; PCT No. WO 95/32305 (Hydig-Hielsen et al.)), phosphorothioate linkages, methylphosphonate linkages or combinations of known linkages. Sugar moieties of the nucleic acid may be ribose or deoxyribose, or similar compounds having known substitutions, e.g., 2′ methoxy and/or 2′ halide substitutions. Nitrogenous bases may be conventional bases (A, G, C, T, U), known base analogs (e.g., inosine; see The Biochemistry of the Nucleic Acids 5-36, Adams et al., ed., 11.sup.th ed., 1992), or known derivatives of purine or pyrimidine bases (PCT No. WO 93/13121 (Cook)) and a “basic” residues in which the backbone includes no nitrogenous base for one or more residues (U.S. Pat. No. 5,585,481 (Arnold et al.)). A nucleic acid may comprise only conventional sugars, bases and linkages, as found in RNA and DNA, or may include both conventional components and substitutions (e.g., conventional bases linked via a methoxy backbone, or a nucleic acid including conventional bases and one or more analogs).
[0045] By “probe” is meant a nucleic acid oligomer that hybridizes specifically to a target sequence in a nucleic acid or its complement, preferably in an amplified nucleic acid, under conditions that promote hybridization, thereby allowing detection of the target or amplified nucleic acid. Detection may either be direct (i.e., resulting from a probe hybridizing directly to the target sequence or amplified nucleic acid) or indirect (i.e., resulting from a probe hybridizing to an intermediate molecular structure that links the probe to the target sequence or amplified nucleic acid). A probe's “target” generally refers to a sequence in (i.e., a subset of) a larger nucleic acid sequence that hybridizes specifically to at least a portion of the probe sequence by standard hydrogen bonding (base pairing). Sequences that are “sufficiently complementary” allow stable hybridization of a probe oligomer to a target sequence, even if the two sequences are not completely complementary. A probe may be labeled or unlabeled, depending on the detection method used, which methods are well known in the art.
[0046] By “separating” or “purifying” is meant that one or more components of the biological sample are removed from other sample components. Sample components generally are an aqueous solution that includes nucleic acids and other materials (e.g., proteins, carbohydrates, lipids and/or nucleic acids). A separating or purifying step removes at least about 70%, preferably at least about 90%, and more preferably at least about 95% of the other sample components.
[0047] References here to M Mycobacterium tuberculosis refer to Mycobacterium tuberculosis . The sequence of the entire genome of M Mycobacterium tuberculosis is set forth in TubercuList, found at http://genolist.pasteur.fr/TubercuList/.
EXAMPLES
[0048] The examples below are non-limiting and are merely representative of various aspects and features of the present invention.
Example 1
Material and Methods
Major Kit I:
1. Lysis Buffer I (5 ml)
2. Lysis Buffer II (4 ml)
3. Hybridization Buffer (5 ml)
4. Wash Buffer (60 ml)
[0049] 5. Lysis tubes (1.8 ml, 25 tubes)
6. Hybridization tubes (12×75 mm, 50 tubes)
7. Extension buffer (3 ml, stored in −20° C. after arriving)
Major Kit-II:(50 reactions/kit, store in 4° C.)
1. MagProbe (450 μl, stored in 4° C. after arriving)
Detection kit-I:(250 reactions/kit, store in 4° C.)
1. Blocking buffer (0.5%, 60 ml, stored in 4° C.)
2. Horseradish Peroxidase (HRP) Substrate A (7.5 ml, stored in 4° C.)
3. HRP Substrate B (7.5 ml, stored in 4° C.)
Detection kit-II:(250 reactions/kit, store in −20° C.)
1. Bioactive catalyst (Straptavidin-HRP; BC; 1 mg/ml, 15 μl, stored in −20° C.)
2. Other material and equipments:
1. Magnetic Rack
2. NALC (N-acetyl-L-cysteine)
[0050] 3.4% NaOH solution
4. 2.94% sodium citrate solution
5. PBS, pH7.0
[0051] 6. 0.1% PBST (PBS with 0.1% tween-20)
7. 0.5% PBST (PBS with 0.5% tween-20)
8. Magnetic Dry Bath
[0052] 9. Berthol Luminometer with PC connection
Procedures:
I. Decontamination of Clinical Samples (Performed in P 3 Level Laboratory)
[0053] 1. Collect and keep clinical samples in 4° C. refrigerator.
2. Dissolve 1 g of NALC into 100 ml of sterile 4% NaOH and 100 ml of 2.94% sodium citrate solution (daily prepared).
3. Add equal volume of NaOH-citrate-NALC into each clinical sample.
4. Vortex for 30 second and invert sample tube for several times keep in room temperature (RT) for 15 minutes.
5. Add PBS to 50 ml level of sample tube, then centrifuge at 3000 rpm for 20 minutes.
6. Remove supernatant and use 1 ml of PBS to resuspend precipitate.
II. Lysis of Precipitate (can be Performed in P 2 Laboratory)
[0054] 1. Mix 10 ml ddH 2 O with 1 ml of resuspended precipitate. Vortex 20 sec, then centrifuge at 3,800 rpm for 15 min.
2. Remove supernatant; add 150 μl of Lysis buffer I and vortex for 1 min. Keep at RT for 10 min.
3. Keep Lysis tube in 100° C. water bath for 20 min and then add 125 μl of Lysis buffer II.
4. Centrifuge at 10,000 rpm for 2 min, collect DNA lysate and store it in −20° C. freezer.
III. Target Amplification:
[0055] 1. Set up a new 0.2 ml microfuge tube by adding up the following reagent:
[0000]
Reagent
Volume
DNA
1
μl
Reaction mixture *
49
μl
* The reaction mixture contains the following cocktail:
[0000] !Reagent? Volume 10X extension buffer 5 μl #1 primer (GCACGTCGCGGACCTCC) 5 μl #2 primer (CGCCGCGATCAAGGAG) 5 μl dNTP 1 μl Taq DNA polymerase(2U/μl) 0.5 μl ddH 2 O 32.5 μl
2. Initiate the following program with heated lid enabled
Extension Program:
[0056]
[0000]
Temperature
Time
Number of cycles
1
94°
C.
3
min
1
cycle
2
94°
C.
1
min
40
cycles
55°
C.
1
min
72°
C.
30
sec
3
72°
C.
5
min
1
cycle
4
4°
C.
Hold
—
IV. Hybridization
[0057] 1. In a hybridization tube, mix 115 μl of ddH 2 O, 15 μl of MagProbe, 150 μl of hybridization buffer and 20 μl of each amplified DNA sample together.
2. Keep hybridization tubes at 95° C. dry bath for 5 min.
3. Transfer hybridization tubes to a 60° C. dry bath and hold for 20 min.
4. Transfer hybridization tubes to magnetic wells of a magnetic dry bath and hold for 5 min.
5. Remove hybridization buffer by aspiration.
6. Add 1 ml of pre-heated 60° C. Wash buffer to each tube, vortex and put tubes back to magnetic wells and hold for 5 min.
7. Remove hybridization buffer by aspiration.
8. Repeat Step 6-7.
[0058] 9. Keep hybridization tubes at RT.
V. Detection
[0059] 1. Add 200 μl of blocking solution into each tube, vortex.
2. Add 5 μl of freshly prepared BC (99 μl 0.1% PBST+1 μBC stock), vortex and disperse evenly. Sit at RT for 20 min. Avoid light.
3. Put hybridization tubes into magnetic rack and sit for 5 min. Then remove solution by aspiration.
4. Add 1 ml of 0.5% PBST, vortex and put tubes back to magnetic rack. Sit for 5 min then remove solution by aspiration. Repeat once.
5. Use 200 μl of PBS each tube to resuspend magnetic beads by vortexing.
6. Take 20 μl of resuspend solution from step 5.
7. Add 50 μl of mixed substrate to each tube (25 μl substrate A+25 μl substrate B).
8. Read luminescence by Luminometer.
VI. Interpretation of Results (the Same Interpretation)
[0060] 1. ≧100,000 RLU: Positive for drug-sensitive M. tuberculosis
2. <25,000 RLU: Positive for drug-resistant M. tuberculosis
3. 25,000˜100,000 RLU: Probable drug-resistant M. tuberculosis positive;
Retest to verify results.
1. Retest value≧25,000 RLU: Positive for drug-sensitive M. tuberculosis.
2. Retest value<25,000 RLU: Positive for drug-resistant M. tuberculosis
Example 2
[0061] Following the above procedures, ten fentogram (10 fg) of genomic DNA from wild type M. tuberculosis were analyzed using five probes: P 1 , P 2 , P 3 , P 4 and P 5 . It is clearly indicated in FIG. 2 that the probe 1 , 2 and 5 showed high RLU value when reacting with genomic DNA from wild type M. tuberculosis strains W 191 and W 192 .
Example 3
[0062] As indicated in FIG. 3 , probe P 1 , P 2 , P 3 , P 4 and P 5 exhibited high RLU value when reacted with wild type M. tuberculosis strains W 191 and W 192 but low RLU when reacted with Rifampin-resistant M. tuberculosis strains Y 94 , P 80 and Y 194 .
Example 4
[0063] Different samples were assayed by the assay system of the invention. As indicated in FIG. 4 , probe P 1 , P 2 and P 5 clearly differentiates drug-sensitive M. tuberculosis strains W 191 and W 192 from Rifampin-resistant strains Y 94 , P 80 and Y 194 .
Example 5
[0064] Different samples were assayed by the assay system of the invention. As indicated in FIG. 5 , probe P 1 , P 2 and P 5 clearly differentiates drug-sensitive M. tuberculosis strains F 144 w and E 74 w from Rifampin-resistant strains Z 111 R. The results in FIG. 5 were identical to that mentioned prior. These results had shown that the drug-resistant M. tuberculosis detection kits of the invention achieved extremely high sensitivity and specificity.
[0065] While the invention has been described and exemplified in sufficient detail for those skilled in this art to produce and use it, various alternatives, modifications, and improvements should be apparent without departing from the spirit and scope of the invention.
[0066] One skilled in the art readily appreciates that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The cell lines, embryos, animals, and processes and methods for producing them are representative of preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention. Modifications therein and other uses will occur to those skilled in the art. These modifications are encompassed within the spirit of the invention and are defined by the scope of the claims.
[0067] It will be readily apparent to a person skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention.
[0068] All patents and publications mentioned in the specification are indicative of the levels of those of ordinary skill in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference.
[0069] The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations, which are not specifically disclosed herein. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.
[0070] Other embodiments are set forth within the following claims.
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The present invention relates to methods, kits and assay system for detecting drug-resistant Mycobacterium tuberculosis of suspected patient. The system of the present invention largely reduces the whole process of drug-resistant M. tuberculosis detection in less than 5 hours.
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BACKGROUND OF THE INVENTION
This invention relates to a non-retrievable plug for sealing the bore of hollow cylindrical or tubular members, particularly conductor pipe employed with offshore platforms, and to a method for sinking such conductor pipes.
A typical offshore platform has a plurality of conductor pipes running from the top of the platform to the bottom thereof. After the platform is set in place, the conductor pipes are driven into the sea bottom and wells drilled from the platform through the pipes. To give added buoyancy to the platform as it is moved and set in place, the end of each conductor pipe is sealed with a plug to prevent the ingress of water. As an offshore platform may be 1,000 or more feet from top to bottom, the plug in the conductor pipe must be capable of withstanding large hydrostatic pressures when the platform is installed on the sea bottom.
Several different prior art approaches have been taken in plug design and construction. One typical prior art plug comprises a steel cup retained within a cylindrical housing welded to the end of a conductor pipe of the same diameter. The steel cup is retained within the housing by means of a molded elastomeric member which has a portion of the cup retrieving cable spirally wrapped within. To retrieve the cup from the conductor pipe an upward force is applied to the free end of the cable at the top of the pipe, whereupon the cable molded in the elastomeric member progressively rips the elastomeric member apart, freeing the steel cup to move upwardly in the conductor pipe. Such a plug is easy to use, but it is difficult to control the molding process and the accurate placement of the cable within the elastomeric member to ensure proper performance. Furthermore, this type of plug leaves a residue of elastomeric material within the conductor pipe, which may, if large enough, interfere with subsequent drilling operations through the pipe. Another approach to conductor pipe plugs is disclosed in U.S. Pat. No. 4,178,967, issued on Dec. 18, 1979 to Steven G. Streich and assigned to the assignee of the present application. The patent discloses a retrievable, reusable conductor pipe plug which is mechanically locked into place in a housing welded to the bottom of the conductor pipe until it is retracted and withdrawn from the conductor pipe by application of upward force on a cable. While this type of plug is reusable, manufacturing costs are relatively high and failure or jamming of the retraction mechanism is always possible, which events would require the destruction of the plug and removal of the resulting debris, a laborious and difficult procedure. In addition, unless the plug incorporates a device to equalize pressure on both sides of the plug, it is necessary to fill the conductor pipe with fluid prior to removal to prevent rapid and possibly damaging upward movement of the plug due to the large hydrostatic forces acting upon the plug bottom. Finally, certain parts of the plug must be replaced prior to every re-use.
In using the prior art plugs, the step of removing the plug comprises an additional operation to the procedure of driving the conductor pipe and sinking the well therethrough, requiring additional time on the job as well as care in removing the plug.
SUMMARY OF THE INVENTION
In contrast to the prior art, the present invention is a destructible, non-retrievable, single-use plug comprising a cylindrical housing filled with a core of frangible material, the housing being fixed to the end of a conductor pipe of like diameter. The physical configuration of the frangible material, as well as its composition, may be altered depending on the hydrostatic pressure to be encountered, and whether the operator wishes to break up the plug core at the same time the conductor pipe is being driven, or wishes to drill it out after it is embedded in the sea bottom by the drill used to sink the well associated with that conductor pipe. Thus, there is disclosed an inexpensive, easily removable plug which does not leave damaging debris in the conductor pipe after use.
The foregoing advantages and the preferred embodiments of the present invention will be better understood from the following specification taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a first preferred embodiment of the present invention.
FIG. 2 is a cross-sectional view of a second preferred embodiment of the present invention.
FIG. 3 is a cross-sectional view of a third preferred embodiment of the present invention.
FIGS. 4, 5, 6 and 7 are cross-sectional views of alternative embodiments of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a first preferred embodiment of the present invention is shown.
The plug 10 comprises a cylindrical housing 11 having a substantially uniform outer diameter 12, and a substantially uniform upper inner surface 13. Below upper inner surface 13 is annular surface 15, defined by chamfered surfaces 14 and 16, thereby forming a channel. Below the aforesaid channel is disposed lower inner surface 17, of substantially the same diameter as surface 13. The lowest extremity of cylindrical housing 11 is outwardly beveled annular surface 18. Within cylindrical housing 11 is core 19 cast or poured of a frangible, preferably cementitious material, having conical upper surface 20 and conical lower surface 21 extending to pointed tip 22. Core 19 extends into the channel defined by annular surface 15 and chamfered surfaces 14 and 16, ensuring its attachment to cylindrical housing 11. The upper edge 23 of cylindrical housing 11 is bonded, as by welding, shown at 24, to the lower edge of conductor pipe 25. Inner surface 26 of conductor pipe 25 is of substantially the same diameter as that of upper inner surface 13 of cylindrical housing 11. Bore 27 of conductor pipe 25 extends from the top of the pipe to plug 10.
A second preferred embodiment is depicted in FIG. 2. Plug 30, like plug 10, comprises cylindrical housing 11, having the same features as previously noted. Cast or poured within housing 11 is a core 32 of frangible, preferably cementitious material, having upper conical surface 33 and lower inverted conical surface 34. Core 32, as core 19 in plug 10, extends into the channel defined by surfaces 14, 15 and 16 of housing 11. Plug 30, as plug 10, is fixed to the bottom of a conductor pipe (not shown) by welding.
A third preferred embodiment is depicted in FIG. 3. Plug 40 again utilizes cylindrical housing 11, having cast or poured within housing 11 frangible core 42. Core 42 has a flat upper surface 43, which is penetrated by axial bore 44. The lower surface of core 42 curves at 45 from the lowest outer edge of housing 11 to flat lower surface 46. As in plugs 10 and 30, core 42 is held within housing 11 by its engagement with the annular channel on the inside of the housing.
A cementitious material which may be used in forming the plug cores disclosed above and hereafter is a concrete based upon Maryneal Incor® cement, available as Pozmix® A cement (Lone Star Special Incor®) from Halliburton Services, Duncan, Oklahoma. However, there are various suitable high compressive and shear strength concretes which have been developed in the petroleum industry as evident to one of ordinary skill in the art.
The use of a particular plug core configuration is dependent on the results the operator sinking the conductor pipe wishes to obtain. Plug 10 of FIG. 1 provides a pointed end which facilitates driving of the conductor pipe, with breakup of the cementitious material later effected by drilling from the inside of the conductor pipe when the well associated with the conductor pipe is sunk. Upper conical surface 20 of core 19 provides a guiding effect to keep the drill bit centered as it encounters the mass. Alternatively, if the operator wishes to effect breakup of the plug core when driving the conductor pipe, plug 30 of FIG. 2 may be employed. Inverted conical surface 34 at the bottom of core 32 directs the driving forces to the center of the mass, where upper conical surface 33 is also oriented to provide a relatively thin, weak point to effect a fracture. Plug 40 of FIG. 3 provides a flat core bottom 46 which may fracture upon the driving of the conductor pipe to which it is attached, depending on the composition of the sea bottom and driving force exerted, as well as axial bore 44 which will facilitate fracture both from driving forces or, if they are not sufficient, from a drill bit encountering upper flat surface 43.
In the preferred embodiments of FIGS. 1, 2 and 3, the core would have a design thickness capable of withstanding 1,000 PSI hydrostatic pressure; this parameter is, of course a matter of choice depending upon the particular application and depth to which the plug is subjected.
DESCRIPTION OF THE ALTERNATIVE EMBODIMENTS
Alternative embodiments of the invention are depicted in FIGS. 4, 5, 6 and 7. As in the preferred embodiments, all of the alternative embodiments employ cylindrical housing 11.
Plug 50 shown in FIG. 4 comprises a cementitious core 51 poured or cast with concave upper surface 52, and curved lower edge 53 leading to flat lower surface 54. Concave upper surface 52 is designed to facilitate drilling out of the plug core by orienting the drill bit toward the center of the mass.
The embodiment of FIG. 5, plug 60, shows core 61 with a flat upper surface 62 and two alternative lower curved surfaces 63 and 64, both of which give a bulbous shape to the end of the plug to facilitate driving into the sea bottom.
FIG. 6, showing plug 70, depicts core 71 having flat upper and lower surfaces 72 and 73, respectively. This shape is, of course, the easiest to form of those disclosed, but possesses no special features to assist conductor pipe driving or subsequent breakings of the plug core.
FIG. 7, showing plug 80, has a relatively simple configuration similar to plug 70, but core 81 has a conical upper surface 82 to provide a weaker center area for possible breakup during driving and to facilitate drilling out, if necesary. Lower surface 83 is substantially flat.
While the embodiments disclosed herein deal with the use of cement as a plug core, the scope of the invention is, of course, not so limited. Any frangible material may be employed, such as glass or hard plastic. The important consideration is that the plug core be able to withstand relatively high static pressure yet be drillable and/or breakable under impact force so as not to interfere with the drill bit, a problem noted with respect to one of the prior art plugs described above. Furthermore, if desired to assure core integrity until drilling out occurs, reinforcing elements of drillable material may be incorporated in the core. The annular channel shown to hold the core in place in the housing of the plug may be replaced with several smaller annular channels or individual depressions in the housing wall, if desired. Furthermore, small protrusions or a shallow annular ring of drillable material fixed to the inner wall of the housing may be employed to hold the core in place.
It is apparent from the foregoing description that the present invention has significant advantages of:
Extremely simple construction;
Low cost;
Ease of quality control;
Positive assurance of removal from the end of the conductor pipe;
Lack of residue or obstructions in the conductor pipe after removal, as the fractured core material is conducted back to the platform with drilling fluid; and
Ease of operation.
Although the invention has been described with reference to sealing off the end of conductor pipe driven from offshore platforms, it is understood that the invention may be employed whenever it is desired to provide a seal across the bore of a cylindrical member, and that conductor pipes or other cylindrical members using the plug of the present invention may be embedded in the sea bottom by methods other than driving; for example jetting may be employed.
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A plug for sealing the end of conductor pipe of off-shore platforms comprising a cylindrical housing filled with a core of cementitious material, the housing being fixed to the end of the conductor pipe. A method of installing the conductor pipe is also disclosed.
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FIELD OF THE INVENTION
The present invention relates to a skin whitening cosmetic for eliminating, reducing or preventing skin browning due to ultraviolet light or pigmentation in the skin, e.g., spots or freckles, and more particularly to a cosmetic comprising a base for cosmetics and a linoleic acid-vitamin C ester.
BACKGROUND OF THE INVENTION
Known cosmetics for giving fairness to the facial skin include compositions containing vitamin C or derivatives thereof, reducing agents, or a tyrosinase inhibitor, e.g., a placenta extract. These conventional skin whitening cosmetics exhibit inhibitory activity against melanin production when tested in vitro using tissue cultures. However, they have not succeeded in obtaining sufficient effects on elimination or reduction of pigmentation when actually applied to the skin.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a cosmetic which exhibits excellent skin whitening effects without any adverse side effects when actually applied to the skin.
Other objects and effects of the present invention will be apparent from the following description.
The inventors have conducted extensive investigations and, as a result, found that a linoleic acid-vitamin C ester produces excellent effects on elimination and reduction of pigments deposited in the skin and thus attained the present invention.
That is, the present invention relates to a skin whitening cosmetic containing a compound represented by formula (I): ##STR2## wherein R 1 , R 2 , R 3 and R 4 , which may be the same or different, each represents a hydrogen atom or CH 3 (CH 2 ) 3 (CH 2 CH═CH) 2 (CH 2 ) 7 CO--, provided that at least one of R 1 , R 2 , R 3 and R 4 is not a hydrogen atom.
DETAILED DESCRIPTION OF THE INVENTION
Linoleic acid-vitamin C esters which can be used in the present invention typically include ascorbyl 6-monolinoleate, ascorbyl 5-monolinoleate, ascorbyl 2,5-dilinoleate, ascorbyl 2,6-dilinoleate, ascorbyl 2,5,6-trilinoleate and ascorbyl 3,5,6-trilinoleate. These compounds may be used either individually or in combinations of two or more thereof.
Among these compounds, ascorbyl 6-monolinoleate, ascorbyl 2,6-dilinoleate and ascorbyl 2,5,6-trilinoleate, and more preferably ascorbyl 6-monolinoleate and ascorbyl 2,6-dilinoleate, are preferably used in the present invention.
Linoleic acid-vitamin C esters have been known to have the same activities as vitamin C or anti-inflammatory activity as described in Swiss Patent 339,632 but have not yet been known to have a skin whitening effect.
The linoleic acid-vitamin C esters can be prepared by conventional processes for ester synthesis (as described, e.g., in Swiss Patent 339,632 incorporated herein by reference), for example, by the reaction between linoleic acid chloride and ascorbic acid (vitamin C). These processes produce a mixture of linoleic acid-vitamin C esters. In the present invention, such a mixed ester may be used either as it is or after being separated into each ester.
A proportion of the linoleic acid-vitamin C ester(s) in the cosmetic of the present invention is not particularly limited and may be selected from a broad range. It is generally from 0.01 to 10% by weight, preferably from 0.05 to 5% by weight, more preferably from 0.5 to 5% by weight, and particularly preferably from 1 to 5% by weight, based on the total amount of the cosmetic of the present invention.
The skin whitening effect of the linoleic acid-vitamin C esters of the present invention was tested as follows in comparison with other various conventional compounds.
Test Method
Ultraviolet light (UVB intensity: 1 J/cm 2 ) was irradiated on the shaved back of English brown guinea pigs. One week later, a pigmentation was formed.
A linoleic acid-vitamin C ester, vitamin C or other test compound were dissolved in a 70% aqueous solution of ethanol to prepare solutions. The solutions each was then repeatedly applied over 4 weeks on the back of the guinea pigs having the pigmentation. The coated amount was 0.1 ml/cm 2 once per day.
The degree of pigmentation was evaluated based on the following rating system.
0: No reduction of pigmentation was observed (corresponding to the degree of pigmentation on the skin area where no test compound was applied.)
-1: Slight reduction in pigmentation was observed.
-2: Reduction in pigmentation was observed.
The results of the evaluation are shown in Table 1 below.
TABLE 1______________________________________ Concentration Degree ofTest Compound (w/v %) Pigmentation______________________________________None -- 0Vitamin C 1 0Vitamin C 5 0Ascorbyl 6-palmitate 1 0Ascorbyl 6-palmitate 5 0Ascorbyl 6-stearate 1 0Ascorbyl 6-stearate 5 0Ascorbyl 6-linoleate 1 -1Ascorbyl 6-linoleate 5 -2Ascorbyl 2,6-dilinoleate 1 -1Ascorbyl 2,6-dilinoleate 5 -2Ascorbyl 2,5,6-trilinoleate 1 -2Ascorbyl 2,5,6-trilinoleate 5 -2Placenta extract 1 0Placenta extract 5 0______________________________________
As is apparent from the results in Table 1, linoleic acid-vitamin C esters, such as ascorbyl 6-monolinoleate, ascorbyl 2,6-dilinoleate and ascorbyl 2,5,6-trilinoleate exhibit, significant effects on reduction of pigmentation, whereas no such effects are observed in vitamin C or esters thereof with other straight chain saturated fatty acid esters. The cosmetics of the present invention can be formulated into lotions, cosmetic oils, creams, emulsions (or milky lotions), masks (or packs), powders, and so on according to known techniques. For example, the linoleic acid-vitamin C esters may be directly incorporated into cosmetic compositions, such as creams and milky lotions, or may be previously dissolved in an oil phase component of these cosmetic compositions. Also, they may be dissolved in an appropriate solvent, such as alcohols, and then formulated into cosmetics by emulsification, mixing, dispersion, or dissolution.
The cosmetic compositions which can be used in the present invention are not particularly limited and may be any conventional compositions as long as the effects of the present invention are not impaired.
If desired, the cosmetics of the present invention may further contain other conventional components as long as the effects of the present invention are not impaired.
The conventional compositions and its production process as well as the conventional components added therefor of the cosmetic compositions are described, e.g., in Keshohin-Gaku (Cosmetic Science), edited by T. Ikeda, published on May 20, 1979 by Nanzando, Japan, which is incorporated herein by reference, but the present invention is not construed as being limited thereto. Related portions of this reference are shown in Table 2 below.
TABLE 2______________________________________ Compositions and OtherCosmetics production process components______________________________________Lotions page 220, line 14 to page 251, Table 31 page 221, line 12 upCreams page 235, line 9 up to page 227, line 6 up to page 236, line 6 up page 228, line 5Emulsions page 243, line 10 to page 242, line 12 to page 244 line 6 upPacks page 246, line 11 to page 245, line 16 to page 248 line 21Powders page 253, line 3 to page 251, line 10 to page 255, line 8 up page 253, line 2______________________________________
Furthermore, if desired, the cosmetics of the present invention can contain various conventional additives, such as melanin production inhibitors (whitening agents) (e.g., straight chain saturated fatty acid esters of vitamin C and placenta extract), ultraviolet absorbents, ultraviolet scattering agents, anti-inflammatory agents, and antioxidants, as long as the effects of the present invention are not impaired.
Examples of the conventional additives and their addition amounts are shown in Table 3 below but they are not limited thereto. The addition amounts are shown in terms of percent by weight (except Vitamin A) based on the total amount of the cosmetic compositions.
TABLE 3______________________________________ Addition amountAdditives (% by weight)______________________________________Whitening agentPlacenta extract 0.1 to 3Kojic acid 0.1 to 3Photosensitive 0.0001 to 0.002element No. 201Plant extract 0.01 to 1Vitamin A 500 IU to 2,500 IUAnti-inflammatory agentDipotassium 0.01 to 0.2grycyrrhizic acidStearil 0.01 to 0.2grycyrrethinateAllantoin 0.01 to 0.2ε-Aminocaproic acid 0.01 to 0.1Methyl salicylate 0.01 to 0.1Ultraviolet absorbentUrocanic acid 0.01 to 12-Ethoxyethyl 0.01 to 54-methoxycinnamateEthyl paraaminobenzoate 0.01 to 4Oxybenzone 0.01 to 5Octyl salicylate 0.01 to 0.1Ultraviolet scattering agentTitanium oxide 0.1 to 10Zinc oxide 0.1 to 10Kaolin 0.1 to 20Talc 0.1 to 30Magnesium silicate 0.1 to 10AntioxidantDibutylhydroxytoluene 0.01 to 1Butylhydroxyanisole 0.01 to 1Propyl gallate 0.01 to 0.2Tocopherol 0.01 to 1Erythorbic acid 0.0001 to 0.05______________________________________
The cosmetics according to the present invention can be applied to the skin by conventional manners. For example, a lotion containing 1 wt % of the compound of the present invention can be applied by hands 1 to several times per day; one or two drops of a cosmetic oil containing 3 wt % of the compounds can be applied to the portion at which pigmentation occurs by fingers 1 to 3 times per day; a cream containing 5 wt % of the compound can be applied by hands 1 to several times per day; an emulsion containing 2 wt % of the compound can be applied by hands 1 to 3 times per day; and a pack can be used in such a manner that 5 to 10 g of the pack is applied to the facial skin other than eyes and nose, and it allows to stand for about 30 minutes followed by being removed 1 to 2 times per week.
The present invention is now illustrated in greater detail by way of the following Examples, but it should be understood that the present invention is not deemed to be limited thereto. All the percents are by weight unless otherwise indicated.
EXAMPLE 1
______________________________________Lotion:______________________________________Ascorbyl 6-monolinoleate 1.0%Glycerin 6.0%Ethanol 8.0%Polyoxyethylene hydrogenated castor 0.8%oil (60 E.O.)Methyl p-hydroxybenzoate 0.05%Citric acid 0.05%Sodium citrate 0.07%Flavor 0.1%Water-soluble placenta extract 2.0%Purified water balance______________________________________
Glycerin, citric acid, sodium citrate and water-soluble placenta extract were dissolved in purified water. Separately, ascorbyl 6-monolinoleate, polyoxyethylene hydrogenated castor oil (60E.O.), methylparaben (i.e., methyl p-hydroxybenzoate) and the flavor were dissolved in ethanol, and the ethanol solution was added to the above prepared aqueous solution. The mixture was filtered to obtain a lotion. The flavors used in the examples were conventional flavors generally used for cosmetics.
EXAMPLE 2
______________________________________Cosmetic Oil:______________________________________Ascorbyl 2,6-dilinoleate 3.0%Ethyl linoleate 1.0%Retinol acetate 0.3%Cholesteryl stearate 1.0%Olive oil 2.0%Squalane balance______________________________________
In squalane were uniformly dissolved other components to obtain a beauty oil.
EXAMPLE 3
______________________________________Cream:______________________________________Component A:Ascorbyl 6-monolinoleate 5.0%d,l-α-Tocopheryl acetate 0.2%Bleached bees wax (White Wax) 4.0%Cetanol 2.0%Linoleic acid 1.0%Lanolin 2.0%Liquid paraffin 9.0%Self-emulsifiable glycerol monostearate 3.0%Polyoxyethylene sorbitan monostearate 1.5%(20 E.O.)Propyl p-hydroxybenzoate 0.1%Component B:Methyl p-hydroxybenzoate 0.2%Propylene glycol 5.0%Flavor 0.2%Purified water balance______________________________________
A mixture of components A was heat-melted and kept at 80° C. Separately, a mixture of components B other than the flavor was heat-melted and kept at 80° C., and the molten mixture of components A was added thereto while stirring. After sufficient mixing was stirring, the mixture was cooled while stirring, and the flavor was added thereto, followed by cooling to obtain a cream.
EXAMPLE 4
______________________________________Emulsion:______________________________________Component A:Ascorbyl 2,6-dilinoleate 2.0%Stearyl glycyrrhetinate 0.1%Liquid paraffin 5.0%Vaseline 2.0%Bees wax 1.0%Sorbitan sesquioleate 2.0%Component B:Polyoxyethylene oleyl ether (20 E.O.) 2.5%Ethyl p-hydroxybenzoate 0.2%Propylene glycol 5.0%Carboxyvinyl polymer 0.5%Potassium hydroxide 0.3%Flavor 0.2%Purified water balance______________________________________
A mixture of components A was heat-melted and kept at 80° C. Separately, a mixture of components B other than the flavor was heat-melted and kept at 80° C., and the molten mixture of components A was added thereto while stirring. After sufficient mixing with stirring, the mixture was cooled while stirring, and the flavor was added thereto, followed by cooling to obtain an emulsion.
EXAMPLE 5
______________________________________Pack:______________________________________Ascorbyl 2,5,6-trilinoleate 5.0%Oil-soluble placenta extract 2.0%Vinyl acetate-styrene copolymer 10.0%Polyvinyl alcohol 10.0%Sorbitol 5.0%Titanium oxide 8.0%Kaolin 7.0%Ethanol 5.0%Flavor 2.0%Ethyl p-hydroxybenzoate 0.2%Purified water balance______________________________________
Ascorbyl 2,5,6-trilinoleate, the flavor, and ethanol were uniformly mixed to form a solution, and the solution was added to a uniform mixture of the vinyl acetate-styrene copolymer, polyvinyl alcohol, sorbitol, titanium oxide, and kaolin. To the mixture was further added a uniform solution of the oil-soluble placenta extract and ethyl p-hydroxybenzoate in purified water, followed by uniformly mixing to obtain a pack.
The cosmetics according to the present invention, when applied to the skin, exhibit excellent effects to eliminate or reduce browning due to a suntan or pigmentation in the skin.
While the invention has been described in detail with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
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A cosmetic comprising a compound represented by formula (I) is disclosed: ##STR1## wherein R 1 , R 2 , R 3 and R 4 , which may be the same or different, each represents a hydrogen atom or CH 3 (CH 2 ) 3 (CH 2 CH═CH) 2 (CH 2 ) 7 CO--, provided that at least one of R 1 , R 2 , R 3 and R 4 is not a hydrogen atom.
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BACKGROUND OF THE INVENTION
The invention relates to the patterning of circular knitting machines.
The use of striping boxes to increase the versatility of patterns which can be knit on a circular knitting machine is very well known. Conventionally, each striping box is comprised of a plurality of yarn-carrying fingers or other members, for example four such fingers. Often, each feeding station of the circular knitting machine will be provided with a striping box.
Depending upon which one of the four yarn-carrying fingers of each striping box is in dropped or activated state, a different one of four different yarns will be fed to needles travelling past the striping box. By controlling the activation and deactivation of the yarn-carrying fingers at the feeding stations of the machine in accordance with a preselected pattern, it is possible to knit patterns which could not otherwise be produced.
The most common use of striping boxes is in the formation of club stripes, i.e., horizontal stripes having a height, expressed in courses, equal to a multiple of the number of courses which the knitting machine could otherwise produce per needle cylinder rotation if its feeding stations were not provided with striping boxes.
Conventionally, the yarn-carrying fingers of the striping box are activated and deactivated under the control of a control drum provided with removably mounted finger-activating jacks. The jacks may have the form of flat members which are inserted into holding recesses or alternatively pins which are screwed or pushed into holding sockets of the drum. In the latter case, the control drum is provided with a plurality of such holding portions arranged in tracks, each track being associated with one yarn-carrying finger, the holding portions furthermore being arranged in rows, each row corresponding to a predetermined rotation of the needle cylinder.
The control drum is indexed in synchronism with needle cylinder rotation in a manner which is very well known. Usually a control chain is provided having high and low links. The control chain is driven in synchronism with the rotation of the needle cylinder, one link per cylinder rotation. A high link on the control chain causes the control drum to be indexed by one step, whereas a low link on the control chain fails to index the control drum; i.e., the control drum idles. When the control drum is indexed one step in this manner, one control jack or pin will move out of the finger-activating position and another will move into the finger-activating position. If the second control member (jack or pin) is in the same track as the one which it replaces, there will be no change in the activation of the yarn-carrying fingers and the same yarn will continue to be fed; if the second control member is in a track different from the one in which was located the pin which it replaces, then there will be a change in the activation of the yarn-carrying fingers and a different yarn (for example, yarn of a different color) will be fed.
For reasons well known in the art, it is often desired to form a knitted cloth using thick yarns, to give bulk to the cloth or to create any of a variety of special effects. When the feeding station is provided with a striping box, it is conventional practice to thread one of the yarn-carrying fingers of the striping box with the thick yarn. When the thick yarn is to be employed, the finger on which it is threaded is activated. Usually, the thick yarn is too thick to be actually knit and is instead utilized merely as the float for any of a variety of types of lay-in cloth.
A significant drawback of threading one of the thick lay-in yarns onto a yarn-carrying finger of a striping box is that the versatility of the striping box becomes reduced. If the striping box has only four yarn-carrying fingers, then one fourth of its capacity is relegated to the carrying of a yarn which can be laid in only and not knit, or which can at most be knit to the extent of one or a few stitches. This decrease of capacity becomes most apparent, for example, when the pattern to be knit consists of a succession of differently colored and/or patterned horizontal stripes, with only one or a few of the stripes requiring the thick lay-in yarn. Likewise, if two successive stripes of lay-in cloth are to be produced utilizing a thick lay-in yarn of different color for each of the stripes, then two of the four yarn-carrying fingers must be set aside for carrying the two thick lay-in yarns, one for the one stripe and the other for the second. This means that only the two remaining yarn-carrying fingers are available for the carrying of yarn which can actually be knit. This clearly limits very greatly the variety of stripe colors which can be produced.
SUMMARY OF THE INVENTION
It is a general object of the invention to provide a new type of striping-box action which considerably increases the patterning flexibility of circular knitting machines provided with striping boxes.
This general object, and other more specific objects which will become more understandable from the subsequent description of preferred embodiments, can be met, according to one advantageous concept of the invention, by keeping more than one of the yarn-holding members of the striping box of at least one of the feeding stations of the circular knitting machine simultaneously activated so that each of at least some of the needles being fed yarn at such station will receive yarn from each of the more than one activated yarn-holding members.
This expedient makes it possible to achieve several important advantages.
If, for example, the first, second, third and fourth yarn-carrying fingers of each striping box of the knitting machine are respectively threaded with red, blue, white and black yarn, then there exists the possibility of using any combination of two of these yarns to form a double-thickness float for knitting lay-in cloth. Thus, for example, the white and black yarn-carrying fingers may be simultaneously dropped so that the float fed by these fingers to needles travelling past the striping box will consist of one white and one black yarn. The white and black yarn together will give the visual impression of a tweedy colored yarn or, depending upon the size of the yarn and the tightness of the knit and subsequent surface finishing (such as brushing) may even combine to give the impression of a gray lay-in float. If this two-yarn black-white float is utilized to knit a tall club stripe of lay-in cloth, such stripe can be followed by another tall club stripe which utilizes, for example, white but no black yarn, or black but no white yarn. For example, the following club stripe can be a stripe of lay-in cloth wherein the float consists of two yarns, for example a white yarn and a blue yarn, with the body of the stripe being of red yarn and no black yarn being used whatsoever in such stripe.
It will be appreciated that in this way the patterning and design capacity of the knitting machine is greatly increased. On the one hand, it is not necessary to set aside one or more of the yarn-carrying fingers for the holding of a thick lay-in yarn not utilizable for ordinary knitting; on the contrary, the yarn threaded onto each of the yarn-carrying members can be used for ordinary knitting. At the same time, the number of different floats which can be formed for the production of lay-in cloth, or a stripe of lay-in cloth, is greatly increased, being equal to the number of combinations of two different yarns, 16 in the case of four yarn-carrying fingers.
A comparison with the design capacity of prior-art striping boxes can be made in numerical terms. If one considers a prior-art four-finger striping box wherein one finger is relegated to the carrying of a thick yarn which can be used only for lay-in effects and is too thick for actual knitting, then there is available a total of three yarns for knitting and one yarn for a lay-in float. With a comparable four-finger striping box according to the invention, there are available four, not three, yarns for knitting and 16, not just one, different lay-in floats possibilities.
It is possible in some circumstances to simultaneously drop more than two fingers, to combine more than two yarns in forming a lay-in float. When that is feasible, the design flexibility of the knitting machine is even further increased.
A further advantage of the inventive expedient resides in the elimination of the need of back winding two yarns together to form special-order combined yarns for use as lay-in floats. For example, it is known to back wind together two yarns when it is desired to form lay-in fabric wherein the lay-in float is of two colors. Such backwinding is disadvantageous per se in that it requires a separate winding operation. In addition, once two yarns have been backwound to form a combined yarn, it is not feasible to subsequently unwind them to regain the individual component yarns. This is particularly significant because, due to uncertainty as to the actual amount of backwound two-color lay-in yarn which may be needed, it is conventional practice to backwind an amount considerably in excess of the actual need, to avoid an insufficient supply. As a consequence, when a particular order has been filled, the knitter is often left with a supply of two-color backwound combined yarn for which he has no immediate need, or no need whatsoever. Supplies of such unneeded two-color backwound yarn are often accumulated in great quanitity, without any assurance that they can ever be utilized.
The present invention eliminates the need for this expensive, time-consuming and awkward practice of the prior art by making it possible in effect to form two-color yarns for lay-in floats or heavy jersey ends right at the striping box itself, as the production of cloth actually proceeds, and with no commitment to the formation of any particular amount of two-color yarn.
Furthermore, it can actually be more advantageous to form two-color lay-in floats according to the invention than through the use of backwinding. This is because when two yarns of different color are backwound together to form a thicker two-color yarn for a lay-in float, the twisting together of the two component yarns may decrease the extent to which such yarns can be subsequently processed, compared to the extent to which the combined yarns formed according to the present invention can be subsequently processed. For example, if the lay-in cloth is to be brushed, floats formed of component yarns which are not twisted together may be more effectively brushed than backwound float yarns.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a fragmentary top plan view showing the striping box of the invention on a circular knitting machine;
FIG. 2 is an elevational view of the striping box of FIG. 1 taken from the inside of the circular knitting machine;
FIG. 3 is a diagrammatic cross sectional view on the plane of the line 3--3 of FIG. 2;
FIG. 4 is an elevational view of the striping box of FIG. 1 taken from the outside of the circular knitting machine;
FIG. 5 is an enlarged exploded view showing portions of the striping box of FIG. 1;
FIG. 6 is a cross sectional view of the drum of the striping box;
FIG. 7 is a sectional view taken on the plane of line 7--7 of FIG. 6;
FIG. 8 is a fragmentary sectional view showing a conventional finger-actuating jack in one position between drum teeth;
FIG. 9 is a fragmentary sectional view showing the jack of FIG. 8 in a second position between the drum teeth;
FIG. 10 is a fragmentary sectional view showing the jack in a third position between the drum teeth;
FIG. 11 is a fragmentary sectional view showing the jack in a fourth position between the drum teeth;
FIG. 12 is a view similar to FIG. 8 showing one novel jack in a first position between the drum teeth;
FIG. 13 is a view showing the jack of FIG. 12 in a second position between the drum teeth;
FIG. 14 depicts a further novel jack in position between the drum teeth; and
FIG. 15 depicts a striping-box control drum of different design wherein the jacks are replaced by removable control pins.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, as disclosed in U.S. Pat. No. 3,620,049, reference character 10 designates one of a plurality of striping boxes mounted on a stationary carrier ring 12. The striping box 10 contains four striping fingers or yarn carriers 14, 16, 18 and 20, such fingers being of conventional construction and containing apertures through which extend yarns 22, 24, 26 and 28, respectively, from cones on a yarn stand (not shown).
The striping fingers are pivotally mounted on rod 30 between check plates 32 and 34, and are each movable between an upper inoperative position and a lower operative position. When a selected finger such as finger 18 is in its lower operative position, the yarn 26 carried thereby is operatively engageable with a needle 36 whereby the yarn may be knitted into a fabric 35. Movement of the striping fingers from their inoperative to their operative positions determine which striping yarns are incorporated into the fabric.
Each striping box contains an inner rotatable drum 38 mounted on a shaft 40 having one end affixed to an operating lever 42 as by set screw 44. The drum 38 includes a midline annular groove 46 and the like teeth 48 and 50, respectively, on opposite sides of the groove. L-shaped jacks 52 are mounted in selected spaces between the teeth of drum 38 to actuate the striping fingers 14, 16, 18 and 20. Such jacks are held in the drum by a spring 54 which registers with the groove 46 and engages the jacks in one of the recesses formed in the jacks.
Each finger has connected thereto a spring 64 normally urging the rear arm of the finger downwardly and the yarn carrying end of the finger upwardly. The rear arm of a finger, if not engaged by a jack 52, rests upon the surface of the drum teeth and the yarn carrying end of the finger is in its inoperative position. The drum may, however, be moved to bring a jack into a position under the end of the rear arm and so cause elevation of the rear arm and a consequent depression of the forward part of the finger, whereby the finger is brought into its operative position (see finger 18 in FIGS. 1, 2 and 3).
The striping box is operated by an actuator 66 which is responsive to a camming mechanism (not shown) of the type described for example in U.S. Pat. No. 2,543,121. In per se conventional manner, the camming mechanism is controlled by a control chain consisting of high and low links. The control chain is advanced by conventional means one link per rotation of the needle cylinder. A high link activates the camming mechanism and causes the latter to cause the drum 38 to be indexed by one step, so that the next aligned pair of recesses 96 and the jack (if any) therein moves into the position wherein a yarn-carrying finger 14, 16, 18 or 20 becomes activated. A low link in the chain does not activate the camming mechanism, so that the drum 38 will idle, i.e., it will not be indexed during the needle cylinder rotation corresponding to the low link. Actuator 66 includes push rod 68 which acts on one end of lever 42 at 70, the other end 74 of the lever being engageable with a plunger 76 slidably mounted in member 78 and biased against lever 42 by a spring 80. Spring 80, acting through lever 42, urges the push rod 68 to a position wherein flange 82 on the lever engages surfaces 84 on member 78, and the spring is effective to return the lever to such stop engaging position after actuation of the lever by push rod 68.
Drum 38 is operatively connected to a uni-directional roller clutch comprising race 86 affixed in the drum, and rollers 88. The shaft 40 directly engages the rollers 88 and also forms part of the clutch. Whenever lever 42 is actuated by push rod 68, shaft 40 which is affixed to the lever 42 turns a fraction of a revolution and causes the clutch rollers 88 to bind in the race 86 such that the drum is immediately forced to turn with the shaft. As shown the drum 38 includes a number of detents 90 which project from one end surface of the drum, such detents being biased outwardly by springs 92 held in the drum by screws 94. A plurality of recesses 96 equal in number to the number of pairs of aligned teeth in the drum 38 are provided in check plate 34 to receive the detents 90 and cause the drum when actuated by lever 42 acting through shaft 40 to move into a precise position which is defined by engagement of detents 90 in recesses 96 and wherein a pair of slots between adjacent teeth 48 and 50 and any jack therein is disposed directly under the extreme end of the rear part of a striping finger such that the finger is moved into its operative position. After the drum 38 is positioned by the shaft 40, the lever 42 is returned to its stop engaging position by spring 80 and the shaft turns with the lever but without moving the drum which maintains a fixed position wherein the detents 90 register in recesses 96. When the drum is rotated to remove a jack from under a finger, the finger is moved into its inoperative position by attached spring 64. As may be seen in FIG. 7 the shaft 40 is supported for rotation relative to the drum 38 on a ball bearing 98 mounted in a thrust washer 100 which is affixed in the drum. C-ring 102 supports the shaft 40 against longitudinal movement in one direction and the lever 42 prevents longitudinal movement of the shaft in the other direction.
Although striping box 10 has been described as having striping fingers 14, 16, 18 and 20 movable between an upper inoperative position and a lower operative position, it should be appreciated that the striping box construction described is not the only possible construction and that in another construction the striping fingers might, for example, be spring biased toward a lower inoperative position and be subject to actuation by jacks of the striper drum into an upper operative position.
Jacks 52 are located in particular slots of the drum and in particular locations within the slots to provide for operation of the striping levers in a predetermined sequence. As noted hereinbefore, the jacks 52 may be disposed with leg 62 in position A or in position B, and the jacks may also be disposed with leg 60 in position C or position D. The jacks 52 may be slid under the spring 54 between positions A and B or between positions C and D, and may be pivoted (FIG. 10) about the spring 54 between positions B and C. The jack 52 for any particular pair of slots of the drum may therefore readily be positioned to operate any one of the striping fingers 14, 16, 18 or 20.
It will be appreciated that each of the four positions of the jack 52 shown in FIGS. 8-11 causes the activation of a different respective one of the four yarn-carrying fingers 14, 16, 18 or 20. Only one yarn-carrying finger can be actuated at a time using these jacks.
FIGS. 12, 13 and 14 show the use of novel jacks 52' and 52". In FIG. 12, jack 52' has one leg which is of a breadth such as to cause the simultaneous activation of two of the yarn-carrying fingers, corresponding to positions A and also B of the single jack 52. In FIG. 13, jack 52' has been reversed so as to cause the simultaneous activation of the two yarn-carrying fingers corresponding to positions C and D of the single jack 52. FIG. 14 depicts a further novel jack 52" so configurated as to simultaneously activate the two yarn-carrying fingers corresponding to positions B and C of the single jack 52. The jack 52" of FIG. 14 has the advantage over the jack 52' that it can be moved into any of the three positions, so as to simultaneously activate the left two, the middle two, or the right two yarn-carrying fingers 14, 16, 18, 20. It will be appreciated that other designs for the jacks are also possible. For example, a jack can be designed to simultaneously activate the leftmost one and the rightmost one of the four yarn-carrying fingers.
FIG. 15 depicts another well known conventional construction for the control drum of a striping box. Control drum constructions of this type are disclosed, for example, in U.S. Pat. Nos. 2,543,121 and 2,549,701. Here, the jacks 52, 52' or 52" are replaced by a single, a pair, or three control pins 146. It will be seen that row #2 of the control holes is occupied by two adjoining control pins l46, located in the two leftmost tracks of the control drum. Row #3 of the control holes is occupied by a single control pin, located in the leftmost track of the drum. Row #4 of the control drum is occupied by two control pins 146, one located in the leftmost track and the other in the rightmost track.
The control drum of FIG. 15 in per se conventional manner is indexed row by row, in synchronism with the rotation of the needle cylinder. In conventional manner, a (non-illustrated) control chain composed of high and low links controls the indexing of the control drum. The chain is advanced one link per needle cylinder rotation. A high link causes the control drum to be advanced by one row, whereas a low link has no effect upon the control drum so that the control drum idles in the angular position thereof into which it was moved by the most recent high link of the control chain.
Let it be assumed that three successive links of the control chain are each high links and are associated with rows #2, #3 and #4 of the control drum of FIG. 15. Consequently, during the needle cylinder rotation corresponding to row #2, the left two yarn fingers will be activated and the striping box will feed the left two yarns. During the next needle cylinder rotation, only the leftmost yarn finger is activated, and only a single yarn is fed by the striping box. During the subsequent needle cylinder rotation, two yarns are again fed by the striping box, but now the leftmost and rightmost yarns.
It may be that during each of these three needle cylinder rotations the pattern wheel for the feeding station in question is programmed to merely lay in a float. In that event, during the first and third of these rotations a double thickness of yarn will be laid in as, for example, a two-color float, with the color combination being different for the two cylinder rotations. During the second of these rotations, on the other hand, only a single thickness of yarn will be fed as lay-in float.
If the feeding station provided with the striping box of FIG. 15 is provided with a conventional pattern placer mechanism (pattern wheel nullifier), then the latter may be programmed to override the pattern wheel of the feeding station during the second of the aforementioned three rotations. For example, during the first and third of the three rotations it may be desired to knit lay-in cloth wherein the lay-in float is a double-thickness two-color float, whereas during the second of these three rotations it may be desired to activate all pattern placer mechanisms (in proper sequence) so that a stripe of plain jersey cloth will be knit. In that event, the single yarn fed by the striping box of FIG. 15 during the second of the three cylinder rotations will be actually knit into stitches, and not merely laid in as a float in the formation of lay-in cloth.
It is to be understood that in principle more than two of the yarn-carrying fingers can be simultaneously activated, for example to form a three-color triple-thickness lay-in float for lay-in cloth.
It will be appreciated that the increase in design versatility and capability resulting with the expedients described above is very great. The number of combinations of multiple-thickness, multi-color threads which can be formed, as needed, is very considerable. Moreover, not one of the fingers of the striping box need be relegated to the carrying of a lay-in yarn too thick for actual knitting.
The invention has been illustrated and described as embodied in a circular knitting machine and a method of operating the same, where the circular knitting machine is provided with striping boxes which are operated by rotating control drums indexed in synchronism with the rotation of the needle cylinder of the knitting machine. However, the basic concept of the invention would also be applicable to knitting machines of different and especially more complicated design, for example, knitting machines in which the various control operations are performed not by cyclically operated cams and control chain links, but instead under the control of a programmed electronic computer, or the like.
The invention in its broadest aspect embraces the activation of more than one yarn-carrying finger, or other equivalent mechanism of a multi-finger striping box in general, so as to effect the feeding to needles of the yarn from more than one of the yarn-carrying fingers of the striping box at a time.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.
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A circular knitting machine has a rotating needle cylinder provided with cylinder needles disposed about the periphery of the cylinder and a plurality of yarn feeding stations at least some of which are provided with striping boxes. Each striping box has a plurality of yarn-holding members individually activatable for causing yarn from different ones of the yarn-holding members of the striping box to be fed to needles travelling past the striping box. According to the novel method, more than one of the yarn-holding members of the striping box of at least one of the feeding stations are kept simultaneously activated during at least part of a rotation of the needle cylinder so that each of at least some of the needles being fed yarn at such station during such part of a rotation will receive yarn from each of the more than one activated yarn-holding members.
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RELATED APPLICATION
This application is a continuation of U.S. patent application Ser. No. 11/657,042 filed Jan. 24, 2007 now U.S. Pat. No. 7,837,740, the entire disclosure of which is incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally directed toward an allograft cartilage repair implant and is more specifically directed toward a two piece allograft cancellous bone implant having a demineralized cancellous bone cap member and a mineralized or partially demineralized cancellous bone base member, both pieces being held together with an allograft bone pin. The construct is shaped for an interference fit implantation in a shoulder, knee, hip, or ankle joint. The base member is provided with an axially positioned blind bore and a plurality of smaller diameter through-going bores which allow transport of cellular materials throughout the implant site to stimulate cartilage growth.
2. Description of the Prior Art
Articular cartilage injury and degeneration present medical problems to the general population which are constantly addressed by orthopedic surgeons. Every year in the United States, over 500,000 arthroplastic or joint repair procedures are performed. These include approximately 125,000 total hip and 150,000 total knee arthroplastics and over 41,000 open arthroscopic procedure to repair cartilaginous defects of the knee.
In the knee joint, the articular cartilage tissue forms a lining which faces the joint cavity on one side and is linked to the subehondral bone plate by a narrow layer of calcified cartilage tissue on the other. Articular cartilage (hyaline cartilage) consists primarily of extracellular matrix with a sparse population of chondrocytes distributed throughout the tissue. Articular cartilage is composed of chondrocytes, type II collagen fibril meshwork, proteoglycans and water. Active chondrocytes are unique in that they have a relatively low turnover rate and are sparsely distributed within the surrounding matrix. The collagens give the tissue its form and tensile strength and the interaction of proteoglycans with water give the tissue its stiffness to compression, resilience and durability. The hyaline cartilage provides a low friction bearing surface over the bony parts of the joint. If the lining becomes worn or damaged resulting in lesions, joint movement may be painful or severely restricted. Whereas damaged bone typically can regenerate successfully, hyaline cartilage regeneration is quite limited because of it's limited regenerative and reparative abilities.
Articular cartilage lesions generally do not heal, or heal only partially under certain biological conditions due to the lack of nerves, blood vessels and a lymphatic system. The limited reparative capabilities of hyaline cartilage usually results in the generation of repair tissue that lacks the structure and biomechanical properties of normal cartilage. Generally, the healing of the defect results in a fibrocartilaginous repair tissue that lacks the structure and biomedical properties of hyaline cartilage and degrades over the course of time. Articular cartilage lesions are frequently associated with disability and with symptoms such as joint pain, locking phenomena and reduced or disturbed function. These lesions are difficult to treat because of the distinctive structure and function of hyaline cartilage. Such lesions are believed to progress to severe forms of osteoarthritis. Osteoarthritis is the leading cause of disability and impairment in middle-aged and older individuals, entailing significant economic, social and psychological costs. Each year, osteoarthritis accounts for as many as 39 million physician visits and more than 500,000 hospitalizations. By the year 2020, arthritis is expected to affect almost 60 million persons in the United States and to limit the activity of 11.6 million persons.
There are many current therapeutic methods being used. None of these therapies has resulted in the successful regeneration of hyaline-like tissue that withstands normal joint loading and activity over prolonged periods. Currently, the techniques most widely utilized clinically for cartilage defects and degeneration are not articular cartilage substitution procedures, but rather lavage, arthroscopic debridement, and repair stimulation. The direct transplantation of cells or tissue into a defect and the replacement of the defect with biologic or synthetic substitutions presently accounts for only a small percentage of surgical interventions. The optimum surgical goal is to replace the defects with cartilage-like substitutes so as to provide pain relief, reduce effusions and inflammation, restore function, reduce disability and postpone or alleviate the need for prosthetic replacement.
Lavage and arthroscopic debridement involve irrigation of the joint with solutions of sodium chloride, Ringer or Ringer and lactate. The temporary pain relief is believed to result from removing degenerative cartilage debris, proteolytic enzymes and inflammatory mediators. These techniques provide temporary pain relief, but have little or no potential for further healing.
Repair stimulation is conducted by means of drilling, abrasion arthroplasty or microfracture. Penetration into the subchondral bone induces bleeding and fibrin clot formation which promotes initial repair, however, the tissue formed is fibrous in nature and not durable. Pain relief is temporary as the tissue exhibits degeneration, loss of resilience, stiffness and wear characteristics over time.
The periosteum and perichondrium have been shown to contain mesenchymal progenitor cells capable of differentiation and proliferation. They have been used as grafts in both animal and human models to repair articular defects. Few patients over 40 years of age obtain good clinical results, which most likely reflect the decreasing population of osteochondral progenitor cells with increasing age. There have also been problems with adhesion and stability of the grafts, which result in their displacement or loss from the repair site.
Transplantation of cells grown in culture provides another method of introducing a new cell population into chondral and osteochondral defects. CARTICELL® is a commercial process to culture a patient's own cartilage cells for use in the repair of cartilage defects in the femoral condyle marketed by Genzyme Biosurgery in the United States and Europe. The procedure uses arthroscopy to take a biopsy from a healthy, less loaded area of articular cartilage. Enzymatic digestion of the harvested tissue releases the cells that are sent to a laboratory where they are grown for a period ranging from 2-5 weeks. Once cultivated, the cells are injected during a more open and extensive knee procedure into areas of defective cartilage where it is hoped that they will facilitate the repair of damaged tissue. An autologous periosteal flap with a cambium layer is used to seal the transplanted cells in place and act as a mechanical barrier. Fibrin glue is used to seal the edges of the flap. This technique preserves the subchondral bone plate and has reported a high success rate. Proponents of this procedure report that it produces satisfactory results, including the ability to return to demanding physical activities, in more than 90% of patients and those biopsy specimens of the tissue in the graft sites show hyaline-like cartilage repair. More work is needed to assess the function and durability of the new tissue and determine whether it improves joint function and delays or prevents joint degeneration. As with the perichondrial graft, patient/donor age may compromise the success of this procedure as chondrocyte population decreases with increasing age. Disadvantages to this procedure include the need for two separate surgical procedures, potential damage to surrounding cartilage when the periosteal patch is sutured in place, the requirement of demanding microsurgical techniques, and the expensive cost of the procedure which is currently not covered by insurance.
Osteochondral transplantation or mosaicplasty involves excising all injured or unstable tissue from the articular defect and creating cylindrical holes in the base of the defect and underlying bone. These holes are filled with autologous cylindrical plugs of healthy cartilage and bone in a mosaic fashion. The osteochondral plugs are harvested from a lower weight-bearing area of lesser importance in the same joint. This technique, shown in Prior Art FIG. 2 , can be performed as arthroscopic or open procedures. Reports of results of osteochondral plug autografts in a small numbers of patients indicate that they decrease pain and improve joint function, however, long-term results have not been reported. Factors that can compromise the results include donor site morbidity, effects of joint incongruity on the opposing surface of the donor site, damage to the chondrocytes at the articular margins of the donor and recipient sites during preparation and implantation, and collapse or settling of the graft over time. The limited availability of sites for harvest of osteochondral autografts restricts the use of this approach to treatment of relatively small articular defects and the healing of the chondral portion of the autograft to the adjacent articular cartilage remains a concern.
Transplantation of large allografts of bone and overlying articular cartilage is another treatment option that involves a greater area than is suitable for autologous cylindrical plugs, as well as for a non-contained defect. The advantages of osteochondral allografts are the potential to restore the anatomic contour of the joint, lack of morbidity related to graft harvesting, greater availability than autografts and the ability to prepare allografts in any size to reconstruct large defects. Clinical experience with fresh and frozen osteochondral allografts shows that these grafts can decrease joint pain, and that the osseous portion of an allograft can heal to the host bone and the chondral portion can function as an articular surface. Drawbacks associated with this methodology in the clinical situation include the scarcity of fresh donor material and problems connected with the handling and storage of frozen tissue. Fresh allografts carry the risk of immune response or disease transmission. Musculoskeletal Transplant Foundation (MTF) has preserved fresh allografts in a media that maintains a cell viability of 50% for 35 days for use as implants. Frozen allografts lack cell viability and have shown a decreased amount of proteoglycan content which contribute to deterioration of the tissue.
A number of United States patents have been specifically directed towards bone plugs which are implanted into a bone defect. Examples of such bone plugs are U.S. Pat. No. 4,950,296 issued Aug. 21, 1990 which discloses a bone graft device comprising a cortical shell having a selected outer shape and a cavity formed therein for receiving a cancellous plug, which is fitted into the cavity in a manner to expose at least one surface; U.S. Pat. No. 6,039,762 issued Mar. 21, 2000 discloses a cylindrical shell with an interior body of deactivated bone material and U.S. Pat. No. 6,398,811 issued Jun. 4, 2002 directed toward a bone spacer which has a cylindrical cortical bone plug with an internal through-going bore designed to hold a reinforcing member. U.S. Pat. No. 6,383,211 issued May 7, 2002 discloses an invertebral implant having a substantially cylindrical body with a through-going bore dimensioned to receive bone growth materials.
U.S. Pat. No. 6,379,385 issued Apr. 30, 2002 discloses an implant base body of spongious bone material into which a load carrying support element is embedded. The support element can take the shape of a diagonal cross or a plurality of cylindrical pins. See also, U.S. Pat. No. 6,294,187 issued Sep. 25, 2001 which is directed to a load bearing osteoimplant made of compressed bone particles in the form of a cylinder. The cylinder is provided with a plurality of through-going bores to promote blood flow through the osteoimplant or to hold a demineralized bone and glycerol paste mixture. U.S. Pat. No. 6,096,081 issued Aug. 1, 2000 shows a bone dowel with a cortical end cap or caps at both ends, a brittle cancellous body and a through-going bore.
While these implants have been used for bone tissue regeneration, the same will not work to repair cartilage areas due to the osteoinductive nature of the bone which causes bone growth.
The use of implants for cartilage defects is much more limited. Aside from the fresh allograft implants and autologous implants, U.S. Pat. No. 6,110,209 issued Nov. 5, 1998 shows the use an autologous articular cartilage cancellous bone paste to fill arthritic defects. The surgical technique is arthroscopic and includes debriding (shaving away loose or fragmented articular cartilage), followed by morselizing the base of the arthritic defect with an awl until bleeding occurs. An osteochondral graft is then harvested from the inner rim of the intercondylar notch using a trephine. The graft is then morselized in a bone graft crusher, mixing the articular cartilage with the cancellous bone. The paste is then pushed into the defect and secured by the adhesive properties of the bleeding bone. The paste can also be mixed with a cartilage stimulating factor, a plurality of cells, or a biological glue. All patients are kept non-weight bearing for four weeks and used a continuous passive motion machine for six hours each night. Histologic appearance of the biopsies has mainly shown a mixture of fibrocartilage with hyaline cartilage. Concerns associated with this method are harvest site morbidity and availability, similar to the mosaicplasty method.
U.S. Pat. No. 6,379,367 issued Apr. 30, 2002 discloses a plug with a base membrane, a control plug, and a top membrane which overlies the surface of the cartilage covering the defective area of the joint.
SUMMARY OF THE INVENTION
A cartilage repair allograft construct implant comprising a two piece allograft bone construct with a mineralized cylindrical cancellous bone base member and a demineralized and non-osteoinductive cancellous bone cap member that is mounted in a blind bore cut in the cancellous bone base member. The base and cap members are held together by an allograft bone pin. The two piece construct is used for replacing articular cartilage defects and is placed in a bore which has been cut into the patient to remove the lesion defect area. The bone base member has an axially aligned blind bore, at least one transverse lateral bore which intersects the blind bore, and has a plurality of longitudinal through-going bores which extend parallel to the axis of the cylindrical bone base member. The cap member has a stem which fits into the blind bore of the base member with the stem defining a transverse radial bore. The bottom surface of the cap member overlies the upper surface of the cylindrical base member with the radial bore of the stem and the longitudinal bore(s) of the base member being aligned to receive a cortical bone pin. Additives may be applied to the lateral and/or radial bores, the blind bore or the cap member of the construct in order to increase or accelerate cartilaginous or bony tissue formation. Each allograft construct can support the addition of a variety of chondrogenic stimulating factors including, but not limited to, morselized allogenic cartilage, growth factors (FGF-2, FGF-5, IGF-1, TGF-β, BMP-2, BMP-7, PDGF, VEGF), human allogenic or autologous chondrocytes, human allogenic or autologous bone marrow cells, stem cells, demineralized bone matrix, insulin, insulin-like growth factor-1, transforming growth factor-B, interleukin-1 receptor antagonist, hepatocyte growth factor, platelet-derived growth factor, Indian hedgehog and parathyroid hormone-related peptide or bioactive glue. It is also an object of the invention to provide a cartilage repair implant which is easily placed in a defect area by the surgeon using an arthroscopic, minimally invasive technique.
It is also an object of the invention to provide a cartilage repair implant which is easily placed in a defect area by the surgeon using an arthroscopic, minimally invasive technique.
It is still another object of the invention to provide an allograft implant which has load bearing capabilities.
It is further an object of the invention to provide an allograft implant procedure which is applicable for both partial and full thickness lesions.
It is yet another object of the invention to provide an allograft implant which facilitates growth of hyaline cartilage.
It is an additional object of the invention to provide a cancellous construct which is treated with chondrogenic stimulating factors.
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
The present invention will be further explained with reference to the attached drawings, wherein like structures are referred to by like numerals throughout the several views. The drawings shown are not necessarily to scale, with emphasis instead generally being placed upon illustrating the principles of the present invention.
FIG. 1 is an anatomical illustration of a knee joint having articular cartilage in which a lesion has formed;
FIG. 2 is a schematic illustration of a mosaicplasty procedure, as known in the prior art;
FIG. 3 is an exploded perspective view of a cancellous construct produced in accordance with an exemplary embodiment of the present invention;
FIG. 4 is a top plan view of a base member employed by the construct of FIG. 3 ;
FIG. 5 is a side elevation view of a base member and a cap member employed by the construct of FIG. 3 , wherein the cap member is mounted on the base member;
FIG. 6 is a side elevation view of the base member and cap member of the construct of FIG. 3 , wherein the base member and cap member have been rotated 90° from their position shown in FIG. 5 ;
FIG. 7 is a top perspective view of the base member employed by the construct of FIG. 3 ;
FIG. 8 is a bottom perspective view of the cap member employed by the construct of FIG. 3 ;
FIG. 9 is a top plan view of the cap member of FIG. 8 ;
FIG. 10 is a side elevation view of the cap member of FIG. 8 ; and
FIG. 11 is a side elevational view of the cap member of FIG. 8 , wherein the cap member has been rotated 90° from its position shown in FIG. 10 .
DESCRIPTION OF THE INVENTION
The term “tissue” is used in the general sense herein to mean any transplantable or implantable tissue, the survivability of which is improved by the methods described herein upon implantation. In particular, the overall durability and longevity of the implant are improved, and host-immune system mediated responses, are substantially eliminated.
The terms “transplant” and “implant” are used interchangeably to refer to tissue, material or cells (xenogeneic or allogeneic) which may be introduced into the body of a patient.
The terms “autologous” and “autograft” refer to tissue or cells which originate with or are derived from the recipient, whereas the terms “allogeneic” and “allograft” refer to cells and tissue which originate with or are derived from a donor of the same species as the recipient. The terms “xenogeneic” and “xenograft” refer to cells or tissue which originates with or are derived from a species other than that of the recipient.
The present invention is directed towards a cartilage repair construct constructed of two separate pieces of allograft cancellous bone.
Both pieces of the two-piece allograft construct are to be derived from dense cancellous bone that may originate from proximal or distal femur, proximal or distal tibia, proximal humerus, talus, calceneus, patella, or iliium. Cancellous tissue is first processed into blocks and then milled into the desired shapes. The top piece or cap member is substantially demineralized in dilute acid until the bone contains less than 0.2% wt/wt residual calcium. Subsequently, the resultant tissue form is predominantly Type I collagen, which is sponge-like in nature with an elastic quality. Following decalcification, the tissue is further cleaned and may also be treated so that the cancellous tissue is non-osteoinductive. This inactivation of inherent osteoinductivity may be accomplished via chemical or thermal treatment or by high energy irradiation. In a preferred embodiment, the cancellous cap member is treated with an oxidizing agent such as hydrogen peroxide in order to achieve a non-osteoinductive material. The bottom piece will be formed from mineralized cancellous bone or partially demineralized cancellous bone.
The two piece allograft cancellous construct 20 has a base member 22 with a cap member 30 which is held fixed in place in the base member 22 by a pin 40 . The base member 22 is preferably constructed of mineralized cancellous bone and is shaped in the form of a cylinder for easy insertion into bores cut into the patient to cut away cartilage defect areas. However, the base member 22 may be surface or partially demineralized or contain a region of cortical bone so that it is cortical/cancellous. The body of the base member 22 defines a blind bore 23 which holds a stem 36 of the cap member 30 , as further described below. The bottom surface 24 of the blind bore, as seen in FIGS. 5-7 , has a plurality of longitudinal through-going bores 25 extending through the base member 22 and ending on the distal end surface 26 of the base member, which is preferably planar. The top surface 27 of the base member 22 is also preferably planar, forming a seat for the cap member 30 . A first lateral bore 28 extends generally transversely from an exterior wall of the base member 22 , above the bottom surface 24 of the blind bore 23 , and intersects the blind bore 23 . A second lateral bore 29 extends generally transversely from the exterior wall of the base member 22 , above the bottom surface 24 of the blind bore 23 , and intersects the blind bore 23 so as to be opposite the first lateral bore 28 (see FIGS. 4 , 5 and 7 ) and in coaxial alignment therewith. A second plurality of longitudinal through-going bores 31 are circumferentially positioned around the blind bore 23 parallel to the central axis of the base member 22 and extend from the top surface 27 to the bottom surface 26 . The longitudinal through-going bores 25 and 31 have a smaller diameter than the blind bore 23 , with a diameter ranging from 0.5 to 2.0 mm.
The cap member 30 has a cylindrical top section 32 which has a thickness of about 3 mm with a top planar surface 33 , an outer curved wall 34 and a bottom planar surface 35 which is seated adjacent the top surface 27 of the base member 22 when the components are mounted together. The top surface 33 , while preferably planar may be milled to a degree of curvature that matches the physiological curvature. Larger constructs may have a cap member that has multiple stem sections and a base with an inverse “female” pattern which receives the stem sections.
The cap member 30 includes an integral cylindrical stem 36 that depends from the bottom planar surface 35 of the top section 32 . The stem 36 has a length which is not longer than the depth of the blind bore 23 and has a diameter which is equal to or less than the diameter of the blind bore 23 . The stem 36 includes a transverse radial bore 37 which is aligned with the first and second lateral bores 28 , 29 of the base member 22 to receive a cylindrical pin 40 . More particularly, the pin 40 is inserted radially through the construct 20 to hold the cap member 30 in place within the base member 22 (see FIG. 3 ). The cap member 30 is preferably formed of demineralized cancellous allograft bone with a calcium content of less than 0.2% calcium. Alternatively, the cap member 30 has a substantially demineralized region, such as the top section 32 , with a calcium content of less than 0.2% calcium. The cylindrical pin 40 is preferably constructed of cortical bone and has a length equal to or less than the diameter of the base member 22 . The pin 40 can also be constructed of a synthetic material.
The cap member 30 can be secured to the base member 22 by a staple, suture, press fit or an adhesive compound such as fibrin based glue.
The construct 20 is placed in a defect area bore which has been cut in the lesion area of the bone of a patient with the upper surface 26 of the cap member 30 being slightly proud, slightly below, or substantially flush with the surface of the original cartilage remaining at the area being treated. The construct 20 has a length which can be the same as the depth of the defect or more or less than the depth of the bore. If the construct 20 is the same as the depth of the bore 60 , the base of the implant is supported by the bottom surface of the bore and the top surface 33 of cap 30 is substantially level with the articular cartilage. If the construct 20 is of a lesser length, the base of the construct is not supported but support is provided by the wall of the defect area bore or respective cut out area as the plug is interference fit within the bore or cut out area with the cap being slightly proud, slightly below, or flush with the surrounding articular cartilage depending on the surgeon's preference. With such load bearing support the graft surface is not damaged by weight or bearing loads which can cause micromotion interfering with the graft interface producing fibrous tissue interfaces and subchondral cysts.
Including the pluralities of longitudinal through-going bores 25 and 31 in the construct 20 facilitates cell migration throughout the construct 20 . Such cell migration promotes cartilage growth in the cartilage area and bone growth in the adjacent bone region.
In operation, the lesion or defect is removed by cutting a bore removing a lesion in the implant area. If desired, the open cancellous structure of the cap member 30 may be loaded with a cartilage paste or gel as noted below and/or one or more additives namely recombinant or native growth factors (FGF-2, FGF-5, FGF-7, IGF-1, TGF-β, BMP-2, BMP-4, BMP-7, PDGF, VEGF), human allogenic or autologous chondrocytes, human allogenic cells, human allogenic or autologous bone marrow cells, human allogenic or autologous stem cells, demineralized bone matrix, insulin, insulin-like growth factor-1, interleukin-1 receptor antagonist, hepatocyte growth factor, platelet-derived growth factor, Indian hedgehog parathyroid hormone-related peptide, viral vectors for growth factor or DNA delivery, nanoparticles, or platelet-rich plasma. The construct 20 is then placed in the bore or cut away area in an interference fit with the surrounding walls.
If the construct is moveable within the bore, suitable organic glue material can be used to keep the implant fixed in place in the implant area. Suitable organic glue material can be found commercially, such as for example; USSEEL® or TISSUCOL® (fibrin based adhesive; Immuno AG, Austria), Adhesive Protein (Sigma Chemical, USA), Dow Corning Medical Adhesive B (Dow Corning, USA), fibrinogen thrombin, elastin, collagen, casein, albumin, keratin and the like.
The base of the blind bore 23 of the construct 20 can alternatively be provided with a matrix of minced cartilage putty or gel consisting of minced or milled allograft cartilage which has been lyophilized so that its water content ranges from 0.1% to 8.0% ranging from 25% to 50% by weight, mixed with a carrier of sodium hyaluronate solution (HA) (molecular weight ranging from 7.0×10 5 to 1.2×10 6 ) or any other bioabsorbable carrier such as hyaluronic acid and its derivatives, gelatin, collagen, chitosan, alginate, buffered PBS, Dextran, or polymers, the carrier ranging from ranging from 75% to 50% by weight. The cartilage is milled to a size ranging up to 1 mm.
In the gel form, the minced cartilage has been lyophilized so that its water content ranges from 0.1% to 8.0%, ranging from 15% to 30% by weight and the carrier ranges from 85% to 70% by weight. The particle size of the cartilage when milled is less than or equal to 1 mm dry. The cartilage pieces can be processed to varying particle sizes and the HA or other carrier can have different viscosities depending on the desired consistency of the putty or gel. This cartilage matrix can be deposited into the demineralized cap member. The putty or gel enhances the tissue integration between the plug and host tissue.
It is also envisioned that demineralized bone matrix and/or growth factors such as (FGF-2, FGF-5, FGF-7, IGF-1, TGF-β, BMP-2, BMP-4, BMP-7, PDGF, VEGF) or soluble factors such as insulin, interleukin-1 receptor antagonist, hepatocyte growth factor, Indian hedgehog and parathyroid hormone-related peptide, viral vectors for growth factor or DNA delivery, nanoparticles may be adsorbed or combined with the construct or the cartilage pieces. In another embodiment, platelet-rich plasma may be added to the construct.
It is also envisioned that cells which have been grown outside the patient can be inserted by syringe into the cancellous cap member 30 before, during or after deposit of the construct 20 into the defect area. Such cells include allogenic or autologous, bone marrow cells, stem cells and chondrocyte cells. The cellular density of the cells preferably ranges from 1.0×10 8 to 5.0×10 8 or from about 100 million to about 500 million cells per cc of putty or gel mixture. The cap member 30 can support the previously mentioned chondrogenic stimulating factors.
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 claim:
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The invention is directed toward a cartilage repair assembly comprising a shaped allograft two piece construct with a demineralized cancellous cap and a mineralized cylindrical base member defining a blind bore with a through-going transverse bore intersecting the blind bore. The demineralized cancellous cap has a cylindrical top portion and a smaller diameter cylindrical stem extending away from the top portion which fits into the blind bore of the mineralized base member. The cap stem defines a transverse through-going bore which is aligned with the through-going bore of the base member to receive a cylindrical cortical pin holding the cap within the base member. The shaped structure is dimensioned to fit in a drilled bore in a cartilage defect area so that the assembly engages the side wall of the drilled bore in an interference fit.
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RELATED APPLICATION
[0001] This application claims priority to German Patent Application No. 10120432.9-12 filed Apr. 26, 2001, which application is herein expressly incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to a centered double universal joint, especially for driving, or for drives in, agricultural implements and tractors.
BACKGROUND OF THE INVENTION
[0003] U.S. Pat. No. 3,470,12 describes a centered double universal joint. Two outer joint yokes are each articulatably connected via a cross member to two inner joint yokes. Each inner joint yoke is provided with a bearing housing portion. The bearing housing portions are bolted to one another. The bearing housing portions delimit an annular guiding recess which radially displaceably supports a guiding disc. Floatingly arranged annular guiding plates are provided between both sides of the guiding plates and the inner joint yokes in the guiding recess. The guiding disc has a centrally arranged guiding projection which, on both sides, projects from the guiding disc. A bore starts from each end face of the guiding projection. The bore is initially cylindrical and then hollow-spherical. The outer joint yoke arms of each outer joint yoke are connected to one another by a welded-in bridge. Each bridge has a journal projection with a spherical face that engages the associated bearing bore of the guiding projection of the guiding disc. At high torque values and large articulation angles, this design leads to a concentrated load. Thus, the concentrated load leads to an increase in wear in the region of contact between the spherical journal, associated with the bridge, and the respective cylindrical bearing bore which is engaged by the spherical journal. The purpose of the above-described centring means is to control the connected universal joints onto half the articulation angle between an input shaft and an output shaft in order to achieve constant velocity. If wear leads to play, the relationship is disturbed.
SUMMARY OF THE INVENTION
[0004] It is an object of the present invention to provide a centered double universal joint which ensures accurate control of the universal joints that form the double universal joint onto half the articulation angle. This achieves a long service life.
[0005] In accordance with the invention, a centered double universal joint comprises: A first outer joint yoke has first yoke arms and a first bridge that connects the two first yoke arms. The first bridge carries a first cylindrical bearing journal. A first inner joint yoke includes a first bearing housing portion. A first cross member articulatably connects the first outer joint yoke to the first inner joint yoke. A second outer joint yoke has second yoke arms and a second bridge that connects the two second yoke arms. The second bridge carries a second cylindrical bearing journal. A second inner joint yoke includes a second bearing housing portion. The second bearing housing portion is connected to the first bearing housing portion and forms an annular guiding recess. A second cross member articulatably connects the second outer joint yoke to the second inner joint yoke. A guiding disc has a central guiding projection which projects on both sides of the guiding disc towards the first and the second bearing journal. The guiding projection has a continuous cylindrical bearing bore. The two bearing journals extend into the bearing bore from different ends. The guiding disc is adjustable in the guiding recess. A bearing ball is on each bearing journal. The bearing ball has the shape of an outer spherical zone and has a through-bore. The through-bore enables the bearing ball to be positioned on the bearing journal. The bearing ball is held at least axially with reference to the axis of the bearing journal. The bearing ball has a spherical outer face. A bearing race for each bearing ball is supported in the cylindrical bearing bore. The bearing race supports the spherical outer face of the bearing ball. The bearing race includes a corresponding hollow spherical bore that enables the bearing ball to pivot in all directions. The bearing race and the bearing ball form a preassembled unit. The bearing race has a cylindrical outer face which is adjustably positioned in the cylindrical bearing bore of the guiding disc.
[0006] An advantage of this design is that a lower surface pressure and, in consequence, greatly reduced wear is achieved between the guiding disc bearing bore and the bearing race, on the one hand, and between the bearing race and the bearing ball, on the other hand. This is achieved by a surface to surface contact between the conforming surfaces. In addition, it is possible to provide at least one of the components with a friction-reducing coating or to produce it from a material with advantageous friction value. The bearing ball and the bearing race can be pre-assembled to form one unit. The bearing ball and race are then connected to the associated bearing journal of the outer joint yoke. Finally, the inner joint yoke can be assembled with the cross member and the outer joint yoke. These units can then be connected to the guiding disc.
[0007] According to a further embodiment of the invention, the bearing race is formed as one piece and the bearing ball is pressed into the hollow-spherical bore in the bearing race. The axis of the through-bore extends perpendicular relative to the longitudinal axis of the cylindrical outer face of the bearing race. To achieve as large a joint articulation angle as possible, the bearing race is axially delimited by two end faces. The bearing race defines a longitudinal axis on which the cylindrical outer face is centered. The hollow-spherical bore is axially and eccentrically arranged between the two end faces. This embodiment is additionally advantageous since the process of fitting the bearing ball in the bearing race has been facilitated. This is due to, towards one end face, a larger aperture is obtained in the bearing race relative to the hollow-spherical bore.
[0008] The two bearing housing portions are preferably bolted to one another. Accordingly, a releasable unit is obtained which enables the exchange of components. However, it is also possible to connect the two bearing housing portions to one another after assembly, using a material-locking connection, such as a low-heat welding process. To achieve the largest possible articulation angle and to keep the amount of wear in the bearing region of the guiding disc in the guiding recess to a minimum, annular guiding plates are arranged in the annular guiding recess on both sides of the guiding disc. Also, the guiding recess is closed on the radial outside and open on the radial inside. Further, the outer diameter of the guiding plates is greater than the inner diameter of the guiding recess and smaller than the greatest diameter of the guiding recess. Furthermore, the inner diameter of the guiding plates is greater than the outer diameter of the guiding projection of the guiding disc and smaller than the outer diameter of the guiding disc.
[0009] An advantageous situation, with respect to strength, is achieved if the bridge forms an integral part of the associated outer joint yoke.
[0010] Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from a reading of the subsequent description of the preferred embodiment and the appended claims, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
[0012] [0012]FIG. 1 is a side view, partially in section, of an inventive double universal joint.
[0013] [0013]FIG. 2 is an enlarged section view of a detail Z of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
[0015] [0015]FIG. 1 illustrates a double universal joint with two individual universal joints which are connected to one another by a centring mechanism in accordance with the invention. Both joints each accommodate half the articulation angle when an input shaft is articulated relative to an output shaft in order to ensure constant velocity conditions. The two individual joints are substantially identical in design.
[0016] The double universal joint according to FIG. 1 comprises a first outer joint yoke 1 with two first yoke arms 2 connected to one another at their free ends by a first bridge 3 . The first bridge 3 carries a first bearing journal 4 . The first bearing 4 journal defines an axis 5 and has a cylindrical outer face. A first bearing ball 6 , with a spherical zone shape, is non-displaceably held on the first bearing journal 4 along the first axis 5 . The spherical outer face of the first bearing ball 6 is given the reference number 7 . The first outer joint yoke 1 is articulatably connected to the first inner joint yoke 8 by a first cross member 10 . Via its two yoke arms 2 , the first inner joint yoke 8 is integrally formed onto the first bearing housing portion 9 .
[0017] The second joint includes a second outer joint yoke 11 with two second yoke arms 12 of which, again, only one yoke arm 12 is visible. The two second yoke arms 12 are connected to one another by a second bridge 13 . The second bridge 13 carries a second bearing journal 14 . The second bearing journal 14 has a cylindrical outer face and is centered on the second axis 15 . A second bearing ball 16 is non-displaceably held on the second bearing journal 14 along the second axis 15 . The second bearing ball 16 includes a second spherical outer face 17 . The second outer joint yoke 11 is articulatably connected to the yoke arms of a second inner joint yoke 18 by a second cross member 20 . The yoke arms of the second inner joint yoke 18 are being integral with a second bearing housing portion 19 .
[0018] The first bearing housing portion 9 and the second bearing housing portion 19 are removably connected to one another by bolts 38 . The two bearing housing portions 9 , 19 , together, form an annular guiding recess 21 . The guiding recess 21 is closed on the radial outside and open on the radial inside. A guiding disc 22 is radially adjustably received together with guiding plates 27 arranged on both sides of guiding disc 22 in the guiding recess 21 . The diameters D 1 to D 6 of the two annular guiding plates 27 of the guiding disc 22 and of the guiding recess 21 are adjusted to one another such that it is possible to carry out the adjustment of the guiding disc 22 in the annular guiding recess 21 . The diameters D 1 to D 6 are set according to the adjustment necessitated by the articulation requirement, and to hold the guiding disc 22 securely held in the recess 21 .
[0019] In consequence, the diameter D 1 of the guiding recess 21 is greater than the outer diameter D 3 of the two annular guiding plates 27 and greater than the outer diameter D 5 of the guiding disc 22 . The inner diameter D 4 of the two annular guiding plates 27 , however, is smaller than the outer diameter D 5 of the guiding disc 22 . The guiding disc 22 includes a guiding projection 23 . A cylindrical bearing bore 24 is provided in the guiding projection 23 . The guiding projection 23 projects from the planar faces on both sides of the guiding disc 22 . For this reason, the smallest diameter D 2 of the annular guiding recess 21 is greater than the outer diameter D 6 of the guiding projection 23 . Furthermore, the inner diameter D 4 of the annular guiding plates 27 has to be greater than the outer diameter D 6 of the guiding projection 23 .
[0020] A first bearing race 25 is positioned on the first bearing ball 6 . The hollow spherical bore of the first bearing race 25 is adapted to the spherical outer face 7 of the first bearing ball 6 . The first bearing race 25 includes a cylindrical outside which is displaceably guided in the bearing bore 24 of the guiding projection 23 . The second bearing ball 16 , by its second spherical outer face 17 , is received in a corresponding hollow-spherical bore of a second bearing race 26 . The second bearing race 26 , via its cylindrical outer face, is also displaceably received in the bearing bore 24 of the guiding projection 23 .
[0021] [0021]FIG. 2 is in an enlarged view of the second bearing ball 16 arranged on the second bearing journal 14 . The second bearing ball 16 is provided with a cylindrical through-bore 28 . The second bearing race 26 together with the second bearing ball 16 is received on the cylindrical seat face 29 which represents the outer face of the second bearing journal 14 . The second bearing ball 16 , by means of an end face, is contactingly held against a shoulder 30 of the second bearing journal 14 . The second bearing ball 16 is axially secured along the axis 15 at the second bearing journal 14 by deformation regions 31 distributed along the circumference of the second bearing journal 14 in the region of the end face. The deformation regions 31 lead to an accumulation of material in the region of the other end face of the second bearing ball 16 .
[0022] Furthermore, with reference to the second bearing race 26 it can be seen that the hollow-spherical bore 32 , with its center on the longitudinal axis 37 of the second bearing race 26 , is offset away from the end face 35 towards the end face 36 . As a result, a collar is obtained towards the end face 35 . In the region of the end face 36 , the hollow spherical bore 32 ends in a circular-shaped aperture. In consequence, in the region of the end face 36 , a sufficiently large articulation relative to the second bearing journal 14 and the second bridge 13 is achieved in order to ensure the desired large articulation angle. The collar formed towards the end face 35 provides the second bearing race 26 with the required stiffness. In this region, sufficient free space exists which enables the second bearing ball 16 to project beyond the end face 35 under articulation conditions.
[0023] Furthermore, it can be seen that the second bearing race 26 includes a cylindrical outer face 33 which includes a continuous groove 34 . The second bearing race 26 is displaceably supported by the cylindrical outer face 33 in the bearing bore 24 of the guiding projection 23 . The longitudinal axis 37 , on which the hollow spherical bore 32 is centered, simultaneously forms the axis on which the cylindrical outer face 33 and thus the bearing bore 24 are centered. The first bearing ball 6 and the first bearing journal 4 are designed and arranged as described above in connection with the second bearing ball 16 and the second bearing journal 14 .
[0024] 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 centered double universal joint has a first outer joint yoke ( 1 ) carrying a first cylindrical bearing journal ( 4 ). A unit including a first bearing ball ( 6 ) and a first bearing race ( 25 ) are secured on the journal ( 4 ). Via a cylindrical outer face ( 33 ), first bearing race ( 25 ), the unit is positioned in a bearing bore ( 24 ) of a guiding projection ( 23 ) of a guiding disc ( 22 ). Accordingly, a surface to surface contact is achieved between the cylindrical outer face ( 33 ) and the bearing bore ( 24 ) as well as between the hollow spherical bore ( 32 ) of the bearing race ( 26 ) and the spherical outer face ( 17 ) of the bearing ball ( 16 ). The other outer joint yoke is provided with a similar bearing ball and a bearing race arrangement.
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BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to monitoring of lens aberration during a semiconductor process, and more particularly, to a test key layout for precisely monitoring a 3-foil lens aberration during the fabrication of deep-trench capacitor memory devices by eliminating the COMA aberration.
2. Description of the Prior Art
The relentless drive in the integrated circuit industry toward greater packing density and higher speeds has served as the impetus for optical lithography to reduce printed image sizes. Deep-UV (DUV) lithography has been developed to scale minimum feature sizes of devices on semiconductor chips to sub-micron dimensions. However, all optical projection systems for micro-lithography depart from perfection because of various lens aberrations, especially when large image field size is combined with high numerical aperture (NA). Such aberrations have a variety of effects on lithographic imaging: shifts in the image position, image asymmetry, reduction of the process window, and the appearance of undesirable imaging artifacts. These undesirable effects are sometimes exacerbated through use of resolution enhancement techniques such as phase-shift masks or nonstandard illumination. Consequently, the lens aberration monitoring system plays an important role in the semiconductor processes.
FIG. 1 illustrates an enlarged plan view of a prior art test key layout 10 for monitoring lens aberrations that occur during the fabrication of deep trench (DT) capacitor devices. As shown in FIG. 1 , the test key layout 10 comprises a plurality of DT test pairs including pair A, pair B, and pair C. Each of the pairs A, B, and C comprises a left side DT pattern 12 and a right side DT pattern 14 . Typically, both of the left side DT pattern 12 and right side DT pattern 14 are rectangular shaped and, as specifically indicated, have a length L and width W. According to the prior art, pair A is disposed at a center position of the test key area 20 , the pair B is arranged in 45 degree direction with respect to the pair A in the test key area 20 , while the pair C is disposed in 45 degree direction with respect to the pair B. The pair A and pair C are aligned with a reference Y-axis. As seen, pair C is disposed a distance from the pair A along the ±Y-axis. In the indicated circle region 30 , i.e., the area substantially surrounded by the pair A and pair B, no DT test pair is disposed therein. Typically, the lens aberration is monitored and evaluated by measuring the image distortion of the DT test pair A.
During the fabrication of DT capacitor devices, the image of the DT test pair A is affected by so-called three-foil (3-foil) aberration. However, in the meantime, the image of the DT test pair A is also affected by COMA aberration when using the same optical system. COMA is an aberration, which results in a point object being turned into a pear-shape or comet shape at the focal plane, most commonly off-axis. It is caused by unequal magnification in different zones of a lens for obliquely incident rays from an off-axis object. It is also known in the art that COMA aberration typically results in asymmetric photoresist image patterns in a photoresist layer for the originally symmetric patterns on the photo mask. The above-described prior art test key layout 10 for monitoring lens aberrations is not capable of abstracting the 3-foil aberration effect. Consequently, there is a need in this industry to provide an improved test key layout for precisely and exclusively monitoring single lens aberration effect, but not combined lens aberration effect, during the fabrication of DT capacitor devices.
SUMMARY OF INVENTION
It is therefore the primary object of the present invention to provide a test key layout for precisely monitoring a 3-foil lens aberration during the fabrication of DT capacitor devices by eliminating the COMA aberration.
According to the claimed invention, an H-shaped test key layout is provided. A first test pattern is substantially disposed at a center position of a test key area. The first test pattern consists of a pair of rectangular shaped symmetric patterns having a length L and a width L. The test key area comprises a reference X-Y coordinate. A second test pattern (corner pattern) is arranged in close proximity to the first test pattern in 45-degree directions with respect to the first test pattern. A third test pattern is disposed next to the first test pattern along an X-axis of the reference X-Y coordinate. The first test pattern, second test pattern, and third test pattern are arranged like capital “H” within the test key area.
It is an unexpected benefit of the present invention that by adding the third test pattern next to first test pattern along the reference X-axis, the COMA aberration effect can be eliminated, thereby exclusively monitoring the 3-foil aberration effect during the fabrication of DT capacitor devices.
Other objects, advantages and novel features of the invention will become more clearly and readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:
FIG. 1 is an enlarged plan view of a conventional test key layout for monitoring lens aberrations that occur during the fabrication of DT capacitor devices;
FIG. 2 is a schematic plan view of a test key layout for monitoring lens aberrations during the fabrication of DT capacitor devices according to the first preferred embodiment of this invention; and
FIG. 3 is a schematic plan view of a test key layout for monitoring lens aberrations during the fabrication of DT capacitor devices according to the second preferred embodiment of this invention.
DETAILED DESCRIPTION
The present invention pertains to a test key layout or pattern, which may be made on a photomask or be transferred through the photomask containing the test key layout to a photoresist layer coated on a wafer. The present invention is particularly suited for monitoring the 3-foil aberration during the fabrication of DT capacitor devices with an optical lithographic system utilizing a high numerical aperture (NA) such as NA>0.7 and an off-axis illumination such as QUASAR 90, but not limited thereto.
Please refer to FIG. 2 . FIG. 2 is a schematic plan view of a test key layout 100 for monitoring lens aberrations during the fabrication of DT capacitor devices according to the first preferred embodiment of this invention, wherein like numerals designate the same or similar regions or elements. As shown in FIG. 2 , the test key layout 100 comprises a plurality of DT test pairs including pair A, pair B, pair C and pair D arranged in test key area 20 . Generally, the test key area 20 is defined on a scribe line of a wafer or on peripheral region of a die (not shown). Each of the pairs A, B, C and D comprises a left side DT pattern 12 and a right side DT pattern 14 . Both of the left side DT pattern 12 and right side DT pattern 14 are rectangular shaped and, as specifically indicated, have a length L and width W. According to the preferred embodiment, the dimension (length L and width W) of the left side DT pattern 12 and right side DT pattern 14 and the dimension of the DT capacitors made in the memory array are substantially the same. By way of example, for a 0.11-micron process, the length L of the left side DT pattern 12 and right side DT pattern 14 is 220 nm, and the width W of the left side DT pattern 12 and right side DT pattern 14 is 110 nm. On a photomask, the left side DT pattern 12 and right side DT pattern 14 are opaque regions. Light irradiating the test key area 20 passes through the photomask substrate except the opaque left side DT pattern 12 and right side DT pattern 14 .
According to the present invention, the pair A is substantially disposed at a center position of the test key area 20 , the pair B is arranged in 45 degree direction with respect to the pair A in the test key area 20 , while the pair C is substantially disposed in 45 degree direction with respect to the pair B. The pair A and pair C are aligned with a reference Y-axis. As seen in FIG. 2 , the pair C is disposed a distance (spacing) S 1 from the pair A along the ±Y-axis (supposing that the pair A is located on the coordinate origin of the reference X-Y axis coordinate system). In accordance with the preferred embodiment of this invention, the length L of the left side DT pattern 12 and right side DT pattern 14 is three times the spacing S 1 between the pair A and pair C (i.e., S 1 =3L). In the indicated circle region 30 , i.e., the area substantially surrounded by the pair A and pair B, DT test pair D is disposed therein. The pair A and pair D are aligned with a reference X-axis. As seen in FIG. 2 , the pair D is disposed a distance from the pair A along the ±X-axis.
The pair D is disposed a distance S 2 from the pair B. In accordance with the preferred embodiment of this invention, the length L of the left side DT pattern 12 and right side DT pattern 14 is substantially equal to the spacing S 2 between the pair B and pair D (i.e., S 2 =L). As specifically indicated, the spacing between the left side DT pattern 12 of the pair A and the right side DT pattern 14 of the pair D is denoted as “S 3 ”. In accordance with the preferred embodiment of this invention, the spacing S 3 is substantially equal to the width W of the left side DT pattern 12 and right side DT pattern 14 (i.e., S 3 =W). The arrangement of the pairs A, B, and D is somewhat like a capital “H” within the test key area 20 (H-shaped layout).
It is an unexpected benefit of the present invention that by adding the DT test pair D inside the circle regions 30 next to the pair A, the COMA aberration effect can be eliminated, thereby enabling exclusively monitoring of the 3-foil aberration effect during the fabrication of DT capacitor devices.
Please refer to FIG. 3 . FIG. 3 is a schematic plan view of an H-shaped test key layout 102 for monitoring 3-foil lens aberration during the fabrication of DT capacitor devices according to the second preferred embodiment of this invention, wherein like numerals designate the same or similar regions or elements. Comparing to the first preferred embodiment, the second preferred embodiment as depicted in FIG. 3 is a further simplified version. As shown in FIG. 3 , the H-shaped test key layout 102 comprises a central DT test pair A, and single DT test pattern B″ and single DT test pattern D″ arranged in the test key area 20 . Generally, the test key area 20 is defined on a scribe line of a wafer or on peripheral region of a die (not shown).
The central DT test pair A comprises a left side DT pattern 12 and a right side DT pattern 14 . The left side DT pattern 12 and right side DT pattern 14 , the single DT test pattern (corner pattern) B′ and single DT test pattern (COMA eliminating pattern) D′ are all rectangular shaped and, as specifically indicated, have a length L and width W. According to the preferred embodiment, the dimension (length L and width W) of the left side DT pattern 12 and right side DT pattern 14 and the dimension of the DT capacitors made in the memory array are substantially the same. By way of example, for a 0.11-micron process, the length L is about 220 nm, and the width W is about 110 nm. On a photomask (not shown), the left side DT pattern 12 , right side DT pattern 14 , the single DT test pattern B′ and single DT test pattern D′ are opaque regions. Light irradiating the test key area 20 passes through the transparent photomask substrate except the opaque regions.
According to the second preferred embodiment of the present invention, the DT test pair A is substantially disposed at a center position of the test key area 20 , the single DT test pattern B′ is arranged in 45 degree direction with respect to the DT test pair A in the test key area 20 . In the circle region 30 , i.e., the area substantially defined by the DT test pair A and corner pattern B′, single DT test pattern D′ is disposed therein. The DT test pair A and single DT test pattern D′ are aligned with a reference X-axis. As seen in FIG. 3 , the single DT test pattern D′ is disposed a distance S 3 from the pair A along the ±X-axis. In accordance with the second preferred embodiment of this invention, the length L is substantially equal to the spacing S 2 (i.e., S 2 =L). The spacing S 3 is substantially equal to the width W (i.e., S 3 =W). The arrangement of the pair A, single DT test pattern B′, and single DT test pattern D′ is some-what like a capital “H” within the test key area 20 (H-shaped layout).
Those skilled in the art will readily observe that numerous modification and alterations of the present invention may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
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An H-shaped test key layout for exclusively monitoring 3-foil lens aberration effects during the fabrication of deep-trench capacitor memory devices is disclosed. The COMA lens aberration effect that used to occur along with the 3-foil lens aberration effect is now eliminated by this test key layout.
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PRIORITY CLAIM
This Application claims priority to, and incorporates by reference, U.S. Provisional Patent Application No. 60/203,452, which was filed on May 10, 2000.
FIELD OF THE INVENTION
This invention generally relates to the rehabilitation and improvement of utility conduits, including sewer, water, electrical, natural gas, telephone, telecommunication and similar systems. More particularly, the invention relates to the rehabilitation of conduits such that they may serve their originally intended uses while adding new functionality to the conduits.
BACKGROUND OF THE INVENTION
In recent years, the industry concerned with the rehabilitation of existing water, sewage, natural gas or similar pipelines has grown dramatically as existing infrastructure is found wanting either because of its deterioration or its inability to manage the volume of materials which currently need to be transported.
A parallel, yet separate, industry, which is concerned with telecommunications cable, including high speed fiber optic lines for computer or cable television, and various other uses, is similarly expanding its capacity and reach. However, in many cases this industry is creating new infrastructure, rather than rehabilitating existing lines. The costs involved in expanding telecommunications networks are prohibitive and, unlike water systems, may be indefinitely postponed if costs are excessive. This problem is particularly acute in lower density population areas where the returns on investment in expensive telecommunications lines may be much lower than in more populous areas.
Various methods for replacing or rehabilitating existing conduits are known. The most basic method involves digging up existing pipe and replacing it length by length. U.S. Pat. No. 353,680 to Hurlbut discloses replacement pipes which have multiple chambers for carrying different media. However, the “dig and replace” method is extremely expensive, slow and unnecessarily disturbs the ground surface above the entire length of the conduits.
A improvement over this method essentially comprises digging an access trench or entering manholes at both ends of an old conduit and feeding a new conduit through the length of the old conduit so that the existing conduit is left as a casing around the new conduit. Some of these methods are described in U.S. Pat. Nos. 5,525,049 and 6,058,978, both to Paletta. These methods result in an easier, more efficient and cheaper conduit replacement process that does not disturb the ground above the conduit except for the access trench locations, when necessary. Methods for modifying a pipe so that is becomes a dual containment pipe are also disclosed.
Further examples of patents concerning pipe rehabilitation include U.S. Pat. No. 5,395,472 to Mandich and U.S. Pat. No. 5,971,029 to Smith et al. which concern a second replacement conduit being placed within the first replacement conduit in a two step process so that a space remains between the two liners. The space may contain, for example, a sensing system to detect leaks in the inner most conduit.
U.S. Pat. No. 4,738,565 to Streatfield et al.; U.S. Pat. No. 5,054,677 to Carruthers; U.S. Pat. Nos. 4,983,071; 5,078,546; Re. 35,271; and Re. 35,542, all to Fisk et al. disclose pipe-bursting and spreading methods and apparatuses which can be used to expand the inner diameter of an existing conduit from the inside. The existing conduit is destroyed or spread as an expansion apparatus pushes out from within the conduit and simultaneously compacts the soil which surrounds the conduit. The result is a tunnel which has a larger internal diameter than the original conduit, such that a replacement conduit inserted therein may have an internal diameter which is equal to or larger than the original conduit.
Thus, there is a need for methods for installing replacement or rehabilitating existing utility conduits while simultaneously installing new conduits suitable for telecommunications or other cables in one step, such that existing infrastructure may be utilized and multiple installation procedures may be avoided. Further, there is a need for an installation method which allows costs to be shared by multiple industries. Also, there is a need for a method for simultaneously installing multiple conduit arrangements without reducing the capacity of the original conduit. In addition, there is a need for a system which easily accommodates the needs of different industries by providing uncomplicated methods for separating multiple conduit arrangements such that they can be directed to different destinations or separate independent networks so that system access, maintenance and upgrading remains as efficient as possible.
SUMMARY OF THE INVENTION
The present invention provides a method for rehabilitating a conduit which comprises bursting a first conduit to create a tunnel, and inserting a plurality of new conduits into the tunnel, such that at least one of the new conduits has a capacity equal to or greater than a capacity of the first conduit.
The invention further provides a method wherein the new conduits are inserted simultaneously and are either separate from or removeably connected to one another, such that the new conduits are capable of being diverted from the tunnel at separate locations.
In accordance with another preferred embodiment a method for rehabilitating a conduit which comprises bursting a first conduit to create a tunnel, and inserting a new conduit into the tunnel, the new conduit comprising a plurality of channels, such that at least one of the channels has a capacity equal to or greater than a capacity of the first conduit.
In other preferred embodiments the invention provides methods for simultaneously inserting multiple conduits for various uses into an existing conduit.
The invention further provides methods and related apparatuses for bursting existing conduits to create tunnels, installing new conduits into the tunnels and diverting the new conduits or conduit channels from one another such that they can be directed to different locations.
The invention further provides a junction between two multi channel conduits and a multi channel conduit with an outer annular region which is particularly suitable for drilling such that a central bore may thereby be accessed.
Other objects, features and advantages of the present invention will be apparent when the detailed description of the preferred embodiments of the invention are considered in conjunction with the drawings, which should be construed in an illustrative and not in a limiting sense.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a preferred embodiment of the invention showing a multiple conduit arrangement.
FIGS. 2 ( a ) and 2 ( b ) are perspective views of other preferred embodiments of the invention showing a single conduit with multiple channel arrangements.
FIG. 3 is a perspective view showing a preferred arrangement which may be used to perform a bursting/conduit replacement method of the invention.
FIG. 4 is a perspective view showing a close up view of another preferred arrangement which may be used to perform a bursting/conduit replacement method of the invention.
FIG. 5 is a perspective view of a preferred alignment collar of the invention.
FIG. 6 is a left side view of a preferred bursting head of the invention.
FIG. 7 is a cross sectional view of the bursting head shown in FIG. 6, taken along line 7 — 7 .
FIG. 8 is a perspective view of a preferred arrangement of the multiple conduit system of the invention after installation.
FIG. 9 ( a ) is a perspective view of an adapter which may be used with multi channel conduits.
FIGS. 9 ( b ), 9 ( c ) and 9 ( d ) are cross sectional views of the adapter shown in FIG. 9 ( a ), taken along lines 9 ( b ), 9 ( c ) and 9 ( d ), respectively.
FIG. 10 is a perspective view of one preferred arrangement of the invention showing a junction between two multi channel conduits.
FIG. 11 is a perspective view of another preferred arrangement of the invention showing an arrangement for connecting an end user to a multi channel conduit.
FIG. 12 is a perspective view of another preferred arrangement of the invention showing an arrangement for connecting an end user to a multi conduit system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In a preferred method of the invention, multiple conduits, such as those shown in FIG. 1, are inserted into an existing conduit or a tunnel which is created by bursting or spreading the inner walls of an existing conduit outward to form a tunnel. Methods and apparatuses related to pipe bursting are described in U.S. Pat. No. 4,738,565 to Streatfield et al.; U.S. Pat. No. 5,054,677 to Carruthers; U.S. Pat. Nos. 4,983,071; 5,078,546; Re. 35,271; and Re. 35,542, all to Fisk et al., all of which are incorporated herein by reference (Hereafter referred to as “pipe bursting patents”).
Pipe bursting entails the insertion of a device into a conduit, such as an existing water pipe, and applying pressure to the interior surface of the conduit so that it breaks apart or is spread apart after it is cut down its length. The medium surrounding the conduit, such as soil, is simultaneously compressed by the outward force of the apparatus so that, after the operation is complete, a tunnel with an interior diameter larger than the outer diameter of the original conduit generally results. The walls of this tunnel are generally lined with pieces of conduit and compressed soil. Alternatively, existing conduits may be reamed before new conduits are installed. Reaming is generally defined as a process by which the inner diameter of an existing conduit is increased by cutting or grinding the inner surface of the conduit. As used herein, the term “bursting” or “pipe bursting” refers to any method for expanding the inner diameter of an existing conduit including, but not limited to, the methods and apparatuses detailed below, those described in the aforementioned pipe bursting patents, and other methods, including reaming, which are well known by those familiar with conduit rehabilitation. Various pipe bursting techniques may be used to burst almost any pipe, including, but not limited to those formed of vitrified clay, reinforced concrete, cast iron, ductile iron, asbestos cement and steel.
The advantage of these methods is that a new conduit that has an inner diameter at least as large as the original conduit may be inserted into the tunnel. Thus, in situations where, for example, a sewer line to a home needs to be replaced because of leaking, pipe bursting allows for the insertion of a new conduit which has equal or greater capacity to that of the original conduit. For example, an 8″ diameter conduit can be replaced with a 12″ diameter conduit. This is important in applications where the original conduit is at maximum capacity and the use of a smaller diameter conduit is unacceptable. In technologies using inner sleeves or liners which are inserted into existing conduits, without pipe bursting, it is necessarily the case that the new conduit will have an inner diameter, and capacity, which is somewhat less than the original conduit because the thickness of the liner material occupies some of the inner diameter of the original conduit.
FIG. 1 shows one possible arrangement when a relatively larger diameter conduit 2 , such as that which may be suitable for water or sewage is inserted into a tunnel, after pipe bursting, along with relatively smaller diameter conduits 4 , 6 , 8 , 10 , 12 , 14 and 16 which may, for example, be suitable for fiber optic, electrical, coaxial or other cables. Conduits 4 , 6 , 8 , 10 , 12 , 14 and 16 may also be used to carry fluids or gas depending on the circumstances. The conduits may be manufactured from a variety of materials including at least high density polyethylene, extra high molecular weight polyethylene, medium density polyethylene, polypropylene, polyvinyl chloride or similar materials. Rigid conduits, such as those formed from steel or ductile iron, can also be installed. However, most preferred embodiments utilize a flexible plastic pipe. When rigid conduits are used, there must be sufficient space in the trench or manhole so that sections of conduit may be lowered to the existing conduit without the need for significant bending of the new conduit section. Conduits intended for carrying water or sewage will preferably range in size from approximately 4″ to 18″, and conduits for fiber optic and other cables are preferably in the range of 1 cm to 5 cm. However, the invention may be used to rehabilitate conduits with a 36″ diameter, or larger. Conduits are typically installed in lengths of 200′ to 500′ but may be installed in shorter or much longer sections depending on the type of conduit used and the existing field conditions. Conduits may be joined to one another to increase their overall length by various known methods, including butt fusion. Though a plurality of new conduits may be inserted into an existing conduit, pipe-bursting methods allow, if desired, at least one of the new conduits, conduit 2 as depicted in FIG. 1, to have an inner diameter, and consequential capacity, at least as large as the original conduit which is being replaced (not shown).
In most applications it is beneficial for at least one of the new conduits to have a capacity substantially equal to or greater than the capacity of the existing conduit, though a conduit with a smaller capacity may suffice if its capacity is large enough to handle the media which is carried by the existing conduit, since the existing conduit may not utilize its full capacity. Notably, a new conduit with a smaller diameter may have an equal or even greater capacity than a larger diameter existing conduit because the new conduit may have a smaller C factor (roughness coefficient), i.e. better flow properties.
Conduits 4 - 16 need not be attached, though they may be attached, to conduit 2 . If they are attached it is generally preferred that they be detachable after installation so that they may be diverted to a destination(s) separate from conduit 2 . Also, conduits 4 - 16 may have related or different purposes from one another. Thus, in one possible arrangement, conduit 2 will carry sewage away from a building, conduit 4 will house fiber optic cable and conduit 6 will house coaxial cable. In the most preferred method the new conduits are installed without data or cables therein, as these cables can easily be blown or pulled through the conduits at a later date to meet specific needs. However, any of the conduits shown in FIG. 1 could themselves be fiber optic or other data lines, rather than hollow conduits which will house data cables at some time in the future.
Further, conduits 2 - 16 need not share a common source or destination, so long as they need to travel the same route for any distance these methods are appropriate. In this example, the cost of pipe bursting, if done, and insertion of replacement conduits may be shared, for example, among telecommunications, gas and electric companies and a municipal sewage department.
FIG. 2 ( a ) shows a similar arrangement where an inner wall 18 /outer wall 20 assembly is inserted into a tunnel such that inner channel 22 is created, and has, preferably, though not necessarily, an inner diameter at least equal to the old conduit, and outer channels 24 , 26 and 28 are created by baffles or compartment separators 30 and 32 . Channels 22 , 24 , 26 and 28 and conduits 2 - 16 (FIG. 1) may contain cables, wiring or roping (which may be used to pull cables through at a later date) during installation or may remain essentially empty and available for insertion of various cables or media as the need arises.
FIG. 2 ( b ) is an alternate embodiment in which the outer channels are cylindrical in shape.
Though not shown in the figures, “Fold and Form” technology may also be utilized to install new conduits into a tunnel. Methods and apparatuses related to this system are described fully in U.S. Pat. Nos. 5,525,049 and 6,058,978, both to this applicant, and are incorporated herein by reference. These systems essentially comprise the insertion of a folded liner into existing conduits, expanding them against the inner surface of the existing conduits and setting them to form a permanently relined conduit. Additional liners may be inserted within the first liner which is distanced from the first liner with spacer members. The descriptions of “trenchless rehabilitation” in these patents are complimentary to the methods described in the present application.
FIG. 3 shows a preferred arrangement for installing a multi-conduit system. A reel 34 of coiled pipe 36 (4″ in this example) and multiple fiber pipes 38 , 39 (11 mm in this example) are pulled into an access pit 40 where the pipes are attached to a bursting head 42 . The bursting head 42 is pulled through an existing conduit 44 by a cable or rod 46 , which is attached to a winch 48 at the other end of the existing conduit 44 . Since the outer diameter of the bursting head 42 is larger in diameter than the existing conduit 44 , the bursting head 42 breaks apart the existing conduit 44 as it moves (to the right as shown in FIG. 3) creating a tunnel whose diameter is larger than the original conduit. The bursting action may be enhanced by means of a hammering action that is created by the pulling head itself. This “hammering” action can be caused by pneumatic or hydraulic devices as explained in the aforementioned pipe bursting patents. The conduits 36 , 38 , 39 are simultaneously pulled in behind the bursting head 42 so that in one step a tunnel is created along the path of the existing conduit 44 and a multi-conduit arrangement is installed therein. In this embodiment, the new conduits may be connected at one end to a house 35 and at another end to other conduits 37 running down the center of a street 41 . Alternatively, the bursting head 42 may be pushed or pulled through the existing conduit by various other methods known in the industry which may or may not require a winch or similar apparatus.
FIG. 4 is a close-up view of a similar arrangement where two lengths of 1.25″ conduit 50 , 51 are fed from reel 52 while a larger diameter conduit 54 is fed from a second reel (not shown) through an alignment collar 55 to a bursting head 56 with larger dimensions than that shown in FIG. 3 .
FIG. 5 is a detailed view of a preferred alignment collar 56 which may be bracketed in place in a position as shown in FIG. 4 so that, just prior to insertion within the tunnel, the larger pipe 54 can be aligned by larger guide aperture 58 and conduits 50 , 51 can be aligned through any of smaller guide apertures 60 . The invention may be practiced without the collar, but the collar is helpful for aligning new conduits in deep trenches where the new conduits are bent to a relatively large degree prior to their insertion in the tunnel.
FIG. 6 shows a side view of a bursting head (ref. numeral 42 in FIG. 3; ref. numeral 56 in FIG. 4 ). The bursting head may be in a variety of shapes and sizes, though it is preferred that the bursting head tip 62 be cone shaped or rounded or at least of a smaller diameter than the existing conduit so that it will easily enter into it. At its widest point, the diameter, as measured along line “X” is preferably the same or slightly less than the diameter of the existing conduit in applications where the new conduits are being installed inside the existing conduit. Where, as is most preferred, the existing conduit is being bursted to create a larger tunnel, the diameter must be larger than the inner diameter of the existing conduit. In this embodiment it is the force created by the winch 48 (FIG. 3 ), which is connected by a cable 46 to the bursting head tip 62 , which bursts the pipe, so the bursting head itself need not, unless field conditions make it necessary, include the mechanical structure detailed in the aforementioned pipe bursting patents.
The bursting head further includes flanges 64 , 66 , 68 and 70 to which the new conduits attach before the pulling procedure. Conduit 54 (FIG. 4) may connect to flange 64 , and conduits 50 , 51 (FIG. 4) may connect to any two of flanges 66 , 68 and 70 . The number of flanges surrounding flange 64 may vary depending upon the application.
FIG. 7 is a cross section along line 7 (FIG. 6) of the bursting head. As seen in FIG. 7, flange 64 fits inside of an end of conduit 54 and is removeably affixed thereto with fastening devices 72 , such as bolts, screws or pins, during the pulling process. In similar fashion, flanges 66 and 70 fit inside ends of conduits 50 and 51 , respectively, and are removeably affixed thereto with fastening devices 74 during the pulling process. Other embodiments may include flanges which attach to the outside of the conduits by surrounding a portion of the conduit outer surface. The exact manner in which the conduits are attached to the bursting head is not critical, so long as the conduits may readily be attached at one manhole or access trench and detached at another after being pulled through the tunnel. The flanges may be removeably connected to a variety of conduits including, but not limited to, those shown in FIGS. 2 ( a ) and 2 ( b ), which, in a preferred method, would be connected to flange 64 .
FIG. 8 is a perspective view of a preferred arrangement of the multiple conduit system of the invention after installation. FIG. 8 shows one preferred arrangement whereby the conduit 54 runs directly to, and is accessible from, the sewer manhole 76 . While conduits 50 and 51 diverge from conduit 54 and lead to a telecommunications manhole 78 . Notably, conduit 54 does not enter the telecommunications manhole 78 and conduits 50 and 51 do not enter the sewer manhole 76 . Thus, even though all conduits are installed together for the majority of their lengths, they diverge from one another so that maintenance may be conducted independently on each system. In other embodiments, conduits 50 and 51 may enter the sewer manhole, if desired. As shown in FIG. 8 the sewer pipe 54 does not continue through the manhole but, instead, ends at one end of the manhole and continues at the other. This is generally the case, but the arrangement may vary.
FIG. 9 ( a ) is a perspective view of an adapter which may be used with the multi channel conduits shown in FIGS. 2 ( a ) and 2 ( b ) so as to achieve a diversion of the smaller channels in a similar manner to that shown in FIG. 8 . The adapter redirects channels 80 , 82 , 84 , 86 and 88 from a position on the outer circumference of channel 90 (line 9 ( b )) to a position at one circumferential point of channel 90 (line 9 ( d )), where channels 80 - 88 can be further diverted as a group or independently to different destinations. In a preferred embodiment, the total length of the adapter (from lines 9 ( b ) to 9 ( d )) may be approximately 10 feet. FIGS. 9 ( b ), 9 ( c ) and 9 ( d ) are cross sectional views of the adapter through lines 9 ( b ), 9 ( c ) and 9 ( d ), respectively.
FIG. 10 shows a preferred method of connecting a smaller multi channel conduit to a larger multi channel conduit so that, for instance, a home may gain access to a combination water main/telecommunications conduit arrangement. As shown in FIG. 10, a smaller pipe 92 may be branched off from a main conduit 94 in such a manner that an outer chamber 96 of conduit 92 is in communication with an outer chamber 98 of conduit 94 . Further, inner channel 100 of conduit 92 is in communication with inner channel 102 of conduit 94 . Thus, for example, channels 100 and 102 could carry water or sewage and channels 96 and 98 could carry fiber optic cable. A similar arrangement could be placed in channel 104 for, as an example, a house across the street from the house connected by conduit 92 .
FIG. 11 shows another arrangement wherein channels 108 and 110 of conduit 106 are comprised of a solid material, such as plastic, which may be easily drilled or tapped by a tap 112 so that conduit 118 is in communication with channel 120 and gas or steam may be directed to an end user. In this arrangement, another conduit 114 may be attached to conduit 106 such that channel 116 is in communication with channel 122 and fiber optic cables may be run to the end user.
FIG. 12 shows another arrangement wherein channels 124 and 126 are in communication with conduit 128 ; conduits 130 and 132 are in communication with conduit 134 and conduits 136 and 138 are in communication with conduit 140 . In this embodiment, conduits 128 , 134 , 140 and 142 may be main lines running down a street while conduits 124 , 130 and 136 may run to a house on the street and conduits 126 , 132 and 138 may run to a second house on the street. Conduit 142 may be connected to conduits running to another house (not shown) or may be installed with conduit 128 , 134 and 140 and left for possible use in the future.
While the invention has been described with reference to preferred embodiments, 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. For example, the exact arrangement or dimensions of the conduits or the apparatuses used during the pulling/bursting process may be altered while still accomplishing essentially the same result.
In addition, many modifications may be made to adapt a particular situation 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 embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
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Methods and apparatuses for rehabilitating and increasing the functionality of existing underground conduits wherein a plurality of conduits are simultaneously inserted into an existing conduit by bursting the existing conduit to create a tunnel and inserting a plurality of new conduits into the tunnel, such that at least one of the new conduits has a capacity equal to or greater than the capacity of the existing conduit, are provided. The new conduits are either separate from or removeably connected to one another, such that the new conduits are capable of being diverted from the tunnel at separate locations and the new conduit system can be used primarily for carrying media similar to that of the original conduit or additionally for completely different and unrelated media such as fiber optic cable, coaxial cable or electrical cable.
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CLAIM OF BENEFIT OF PROVISIONAL AND PARENT APPLICATION
This Application is a CIP of U.S. application Ser. No. 10/395,831, filed 24 Mar. 2003 and claims the benefit of the filing date of U.S. Provisional Application No. 60/452,870, filed Mar. 6, 2003.
FIELD OF THE INVENTION
The present invention relates generally to radio telephony, and more specifically to a method and apparatus for receiving and processing a radio signal that is subject to transmission-channel distortion.
BACKGROUND OF THE INVENTION
Radio telephones, commonly called cellular (or “cell”) phones, have become ubiquitous in recent years. Formerly the domain of the wealthy, or those in specialized professions for whom the great expense then associated with them was justified, radio telephones are now used by a majority of the population in this country and in many other regions around the world. Considerable leaps in technology have contributed significantly to this evolution. These advances have not only made radio telephone service available to many subscribers at a reasonable price, but they have also permitted great increases in the capacity of the communication networks providing the service.
The cell phone is so called because it is designed to operate within a cellular network. Such a network has infrastructure that switches and routes calls to and from network subscribers who are using portable radio devices. Rather than having one or two antennas to handle all of this radio traffic, however, the cellular network is divided into a great many smaller areas, or “cells”, each having an antenna of their own. A cellular wireless system has several advantages over a central antenna system. As the cells are much smaller than the large geographic area covered by a central antenna, transmitters do not need as much power. This is particularly important where the transmitter is housed in a small device such as a cell phone. In addition, the use of low-power transmitters means that although the number of them operating in any one cell is still limited, the cells are small enough that a great many may operate in an area the size of a major city. The mobile stations do not transmit with enough power to interfere with others operating in other cells, or at least those cells that are not adjoining. In some networks, this enables frequency reuse, that is, the same communication frequencies can be used in non-adjacent cells at the same time without interference. This permits the addition of a larger number of network subscribers. In other systems, codes used for privacy or signal processing may be reused in a similar manner.
At this point, it should also be noted that as the terms for radio telephones, such as “cellular (or cell) phone” and “mobile phone” are often used interchangeably, they will be treated as equivalent herein. Both, however, are a sub-group of a larger family of devices that also includes, for example, certain computers and personal digital assistants (PDAs) that are also capable of wireless radio communication in a radio network. This family of devices will for convenience be referred to as “mobile stations” (regardless of whether a particular device is actually moved about in normal operation).
In addition to the cellular architecture itself, certain multiple access schemes may also be employed to increase the number of mobile stations that may operate at the same time in a given area. In frequency-division multiple access (FDMA), the available transmission bandwidth is divided into a number of channels, each for use by a different caller (or for a different non-traffic use). Time-division multiple access (TDMA) improves upon the FDMA scheme by dividing each frequency channel into time slots. Any given call is assigned one or more of these time slots on which to send information. More than one voice caller may therefore use each frequency channel. Code-division multiple access (CDMA) operates by spreading and encoding transmissions. By encoding each transmission in a different way, each receiver (i.e. mobile station) decodes only information intended for it and ignores other transmissions.
The number of CDMA mobile stations that can operate in a given area is therefore limited by the number of encoding sequences available, rather than the number of frequency bands. The operation of a CDMA network is normally performed in accordance with a protocol referred to as IS-95 (interim standard-95) or, increasingly, according to its third generation (3G) successors, such as those sometimes referred to as 1xEV-DO and 1xEV-DV, the latter of which provides for the transport of both data and voice information.
A wireless network using any of these schemes employs a certain basic structure such as the one illustrated in FIG. 1 . FIG. 1 is a simplified block diagram illustrating selected components of a wireless transmission system 100 . Wireless transmission system 100 includes a transmit side 105 and a receive side 155 . This illustration implies that the two sides are located in different terminals that are attempting to communicate with each other, although typically a communication terminal will include both transmit and receive functions.
The information to be transmitted, which may be voice or data information, is first provided to an encoder 110 to be encoded into digital form. Note that the terms ‘data’ and ‘information’ may be used interchangeably herein. No formal distinction is thereby intended unless it is specifically stated or apparent from the context. The encoded information is then mapped to symbols in a modulator 120 and provided to transmitter 130 , where it is modulated onto a carrier wave and amplified for transmission via radio channel 150 through antenna 140 .
The receiver 170 receives the transmitted radio frequency (RF) signal x through antenna 160 . The received signal y is processed by the receiver 170 provides and the result {circumflex over (d)} to a demodulator 180 , which recovers the encoded sequence û (as well as it is able) taking into account the characteristics h of channel 150 . This encoded sequence û is provided to a decoder 190 for replication of the originally transmitted information. As should be apparent, the goal of any such communication system is the faithful reproduction of this information.
There are a number of obstacles, however, to reliable and effective transmission of information over the air interface. One of the most significant is multipath fading. Transmitted radio signals, generally speaking, spread out as they propagate, and different portions of the signal may reflect off or be otherwise impeded by the various objects each portion encounters. The result is that the different portions of same signal take different paths to the receiver and therefore arrive at slightly different times. These different portions may then interfere with each other and cause fading.
One manner of addressing this challenge is through the use of transmission diversity, for example time diversity or space diversity. Time diversity involves introducing time-delayed redundancy into the transmitted data and, where the fading is time variant, allows the receiver to more accurately recover the transmitted information. Spatial diversity may also be used. In spatial diversity more than one transmission antenna is used, the antennas being spaced apart at a distance selected to provide a desired level of correlation between the data transmitted by each of the antennas. A combination of these two types of transmit diversity may be referred to as space-time transmit diversity (STTD).
The present invention is a receiver, a system, and a method for utilizing STTD transmitted signals and is of particular advantage when applied to a third-generation CDMA network, for example one operating according to the 1xEV-DV protocol.
SUMMARY OF THE INVENTION
The present invention is directed to the reception of data in radio signals transmitted in a network that employs space-time transmit diversity (STTD). In one aspect, the present invention is a receiver for receiving an STTD transmitted signal including a RAKE-STTD receiver as a first stage of the receiver for receiving and processing the STTD signal and at least a second stage receiver. The second stage receiver performs STTD parallel interference cancellation (STTD-PIC) using the output of the first stage and the received signal as its input, and produces a refined estimate of the transmitted data. The second state preferably includes an STTD-linear minimum mean square error (LMMSE) receiver that is used to process the refined estimate before it is output. The receiver may also include a third stage including an STTD-PIC and an STTD-LMMSE for further processing the output of the second stage to produce a further refined estimate. Stages subsequent to the RAKE-STTD may also process the received signal itself to produce an improved channel estimate.
In another aspect, the present invention is a system for communicating data via radio signals including an STTD transmitter and an STTD-signal receiver having at least one antenna, the receiver including a first stage RAKE-STTD for receiving the radio signals and a STTD-PIC second stage for receiving the output of the RAKE-STTD and further processing it to produced a refined estimate of the transmitted data. The second stage may also include an STTD-LMMSE. The receiver of the system may also include a plurality of antennas to increase the diversity gain.
In yet another aspect, the present invention is a method of receiving a data-bearing radio signal that has been transmitted using STTD including the steps of receiving indications of the received radio signal in a first stage RAKE-STTD receiver and processing the signal in the first stage to produce an estimate of the transmitted data as output, receiving as input in a second stage of the receiver the output of the first stage, and the original received signal as well, and processing the input received in the second stage to produce a refined estimate of the data as output.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified functional block diagram illustrating selected components of a wireless transmission system.
FIG. 2 is a functional block diagram illustrating selected components that may be used on the transmit side of a system employing STTD according to an embodiment of the present invention.
FIG. 3 is a simplified schematic drawing illustrating the antenna configuration of a telecommunication system utilizing transmit diversity for operating according to an embodiment of the present invention.
FIG. 4 is a simplified schematic drawing illustrating the 2-1 diversity transmit antenna diversity configuration of FIG. 3 .
FIG. 5 is a functional block diagram illustrating selected components of a receiver 500 according to an embodiment of the present invention
FIG. 6 is a simplified schematic drawing illustrating the antenna configuration of a telecommunication system utilizing both transmit and receive diversity according to an embodiment of the present invention.
FIG. 7 is a flow chart illustrating a method of receiving and processing a radio signal according to an embodiment of the present invention.
DETAILED DESCRIPTION
FIGS. 1 through 7 , discussed herein, and the various embodiments used to describe the present invention are by way of illustration only, and should not be construed to limit the scope of the invention. Those skilled in the art will understand the principles of the present invention may be implemented in any similar radio-communication device, in addition to those specifically discussed herein.
The present invention presents an innovative design for a hybrid radio receiver that may be used, for example, in a code division multiple access (CDMA) telecommunication system that employs space-time transmit diversity (STTD). As mentioned above, STTD is in many systems an effective way to combat the effects of multipath distortion. FIG. 2 is a functional block diagram illustrating selected components that may be used on the transmit side 200 of a system employing STTD according to an embodiment of the present invention. Naturally, the selected transmission components 200 are arranged with the intent of sending a signal to a compatible receiver (not shown in FIG. 2 ), such as one operable according to an embodiment of the present invention.
The information (data) to be transmitted is provided to encoder 205 , and the encoded information is then provided to modulator 210 . In order to achieve transmit diversity, the modulated bit stream b 0 , b 1 , b 2 , b 3 , . . . is provided to splitter 215 where it is split into two streams: b 0 , b 1 , b 2 , b 3 , . . . and −b 1 *, b 0 *, −b 3 *, b 2 *, . . . (where “*” denotes a complex conjugate). Each of these streams is then spread with respect to time using a spreading code W 32 , such as a Walsh-Hadamard code (length 32), by multiplier 220 and multiplier 230 , respectively. Pilot signals are added to the spread signal in adders 224 and 234 , respectively, then a pseudonoise (PN) code is applied to each stream in respective multipliers 228 and 238 to create two multi-coded spread sequences represented in FIG. 2 by the vectors s and s*.
FIG. 3 is a simplified schematic drawing illustrating the antenna configuration of a telecommunication system 300 utilizing transmit diversity for operating according to an embodiment of the present invention. Transmit antenna TX 1 and transmit antenna TX 2 are both transmitting different forms of the same information for reception by receive antenna RX 1 . In FIG. 3 , the information being transmitted from antenna TX 1 is designated as signals s 0 , s 1 , and the information transmitted from antenna TX 2 as signals −s 1 * , s 0 *. Transmit antennas TX 1 and TX 2 are typically present in the same physical device, for example a wireless network base station, and may form a transmit station as described above in relation to FIG. 2 . Receiver RX 1 , of course, will typically be part of another wireless communication device such as a mobile station. The configuration of FIG. 3 is said to exhibit 2-1 diversity in reference to the number of transmit and receive antennas. Note, however, that for a given transmission there may be any number of intended receiving stations (each having its own antenna). In other words, 2-1 diversity may be used to send broadcast or multicast transmissions, in addition to those intended for a single recipient.
Each combination of transmit antenna and receive antenna defines a channel, and therefore in the embodiment of FIG. 3 there are two, designated h 11 and h 21 . Presuming that antenna TX 1 transmits signal s 0 at time t and s 1 at time t+T, where T is the symbol period, and that antenna TX 2 transmits signal −s 1 * at time t and s 0 * at t+T, then the signals r 0 and r 1 received at receive antenna RX 1 may be characterized as:
r 0 =h 11 s 0 −h 21 s 1 *+n 0 and
r 1 =h 11 s 1 +h 21 s 0 *+n 1 ,
where n 0 and n 1 represent the additive noise at times t and t+T, respectively.
This configuration achieves a diversity order of 2 utilizing a single receive antenna. The STTD-transmitted signals so and si may be decoded (estimated) using the following linear operations:
{tilde over (s)} 0 =h* 11 r 0 +h 21 r 1 *=(| h 11 | 2 +|h 21 | 2 ) s 0 +n
{tilde over (s)} 1 =−h 21 r 0 *+h 11 *r 1 =(| h 11 | 2 +h 21 | 2 ) s 1 +n′
where n and n′ are noise terms.
FIG. 4 is a simplified schematic drawing illustrating the 2-1 diversity transmit antenna diversity configuration 300 of FIG. 3 , except that for simplicity the STTD transmitted signals s 0 , s 1 are generally represented as x 1 and the signals −s 1 *, s 0 * are represented as x 2 . Correspondingly, the received signal r 0 , r 1 are together represented as y and the additive noise v. Note, however, that although only two signals were illustrated in FIG. 3 , the vectors x and y could represent any number of signals.
Using this notation, the received signal y may be represented as:
y = [ H 11 H 21 ] [ x 1 x 2 ] + v
where y=[y n+F , y n+F−1 , . . . y n ] T , with n being the chip index, and F+1 the number of filter (chip equalizer) taps per transmit antenna. In this equation, the transmitted signal vector of size (F+1+L) for the first antenna is x 1 =[x 1,n+F , x 1,n+F−1 , . . . , x 1,n , . . . x 1,n−L ] T (and likewise for the second antenna). Further, v=[v n+F , v n+F−1 , . . . v n ] T , and represents the additive noise sequence of autocorrelation matrix R vv .
H 11 , H 21 are Sylvester matrices of size (F+1)×(F+1+L) containing shifted versions of the corresponding overall channel impulse responses, where h j1 =[h j1,0 , h j1 , . . . h j1,L ] T for j=1, 2.
H 11 = [ h 11 , 0 h 11 , 1 ⋯ H 11 , L 0 ⋯ 0 0 h 11 , 0 h 11 , 1 ⋯ h 11 , L ⋰ ⋮ ⋮ ⋰ ⋰ ⋰ 0 0 ⋯ 0 h 11 , 0 h 11 , 1 ⋯ h 11 , L ] , and H 21 = [ h 21 , 0 h 21 , 1 ⋯ H 21 , L 0 ⋯ 0 0 h 21 , 0 h 21 , 1 ⋯ h 21 , L ⋰ ⋮ ⋮ ⋰ ⋰ ⋰ 0 0 ⋯ 0 h 21 , 0 h 21 , 1 ⋯ h 21 , L ] .
Letting H=[H 11 H 21 ] and
x = [ x 1 x 2 ] , y
can also be expressed y=Hx+v.
On the receive side of the transmission, the transmitted STTD signals are received and processed. FIG. 5 is a functional block diagram illustrating selected components of a receiver 500 according to an embodiment of the present invention. Receiver 500 includes an STTD-RAKE receiver as a first-stage 510 that processes incoming signal y as described above, and outputs estimated encoded bits û and/or symbols {circumflex over (d)}. Note that CDMA devices commonly employ RAKE receivers to combat multipath fading.
The basic principle of the RAKE receiver involves selecting a limited number of individual paths of the transmitted signal. The time-delay between different paths arises because the signal is traveling from the transmitter to the receiver. Each selected path is provided to a different RAKE “finger”.
In operation, each finger of the RAKE-STTD receiver (not shown individually) uses a time-aligner to compensate for the path delay. The pilot PN quadrature spreading is then removed and the characteristics of the transmission channel are estimated using the pilot channels. A code such as a 32-length Walsh-Hadamard code (assuming the same having been employed in the transmitter) is used to despread the received signal, and then the STTD-transmitted signal is decoded as described above. The decoded results of all fingers are then combined and passed to the demodulator to yield the RAKE-STTD output represented in FIG. 5 as û, {circumflex over (d)}. Estimated data û, {circumflex over (d)} is provided to second stage 520 .
The second stage 520 of receiver 500 is a first STTD-PIC, which then operates to refine the estimate as follows. Using K to represent the number of active spreading codes (except those used for the pilot channels), and 11 and 21 represent the overall channel impulse response between each respective transmit antenna and the receive antenna (see, for example, FIG. 3 ). The overall channel impulse response is represented by a Sylvester matrix =[ 11 , 21 ]. Then, setting j=1, {circumflex over (x)} j =[{circumflex over (x)} 1,j T , {circumflex over (x)} 2,j T ] T is used to represent the reconstructed chip signal of a whole transmitted frame from both antennas, based on decisions of the previous stage, of all the active spreading codes of the system (including the pilot)—except the j th spreading code. The multiuser interference “seen” by the j th spreading code is {circumflex over (x)} j where is defined over the entire frame. The PIC of second stage 520 then subtracts this interference from the received chip vector y to produce (ideally) an interference-free signal for the j th spreading code. This signal, which may be represented as y− {circumflex over (x)} j , is then passed through an STTD-LMMSE receiver 525 incorporated as part of second stage 520 to yield the symbol estimates for the j th code for the next stage.
The STTD-LMMSE (linear minimum mean square error) receiver is an LMMSE chip equalizer filter followed by a bank of matched filters, which in turn is followed by a decision device. An LMMSE chip equalizer filter seeks to minimize the mean-squared error between its output and the transmitted chip sequence x n (n being the chip index). In this embodiment, the STTD-LMMSE will try to detect the two transmitted streams (x 1 and x 2 ), and it is the solution to the minimization:
W LMMSE =arg m n E{∥w H y−x n ∥ 2 },
where w is the (F+1)×2 filter to be found and
x n = [ x 1 , n x 2 , n ] .
Minimization of this quantity will lead to R yy W LMMSE =R yx where R yy ≡E{yy H }=HR xx H H +R vv . (R vv is the noise process correlation matrix.) And finally
R yx ≡E{yx n *}=HE{xx n H }=σ x 2 {tilde over (h)} F
where the autocorrelation of the transmitted signal is assumed:
R xx =σ x 2 I,
{tilde over (h)} F is an (F+1)×2 matrix whose first and second columns are the F th columns of H 11 and H 21 (shown above ), respectively (counting starts from 0). Assuming that the transmitted signal is independent of the additive noise, this yields:
w LMMSE = ( HH H + 1 σ x 2 R vv ) - 1 h ~ F .
Naturally, the process described above is repeated with respect to each j=2, 3, . . . K, where K is the number of active spreading codes (a user may have an assigned one, or multiple codes). The symbol estimates and the bit estimates of all users are denoted {circumflex over (d)} (2) , û (2) , respectively and are passed to the third stage 530 of receiver 500 . Third stage 530 is also an STTD-PIC incorporating an STTD-LMMSE 535 , and performs an operation similar to that described above with reference to the (first STTD-PIC of) second stage 520 , but using its input {circumflex over (d)} (2) , û (2) and y to produce a further refined data estimate û (3) , {circumflex over (d)} (3) . Bit or symbol estimates û (3) , {circumflex over (d)} (3) may be provided to a decoder (not shown), or may be subjected to further refinement in one or more additional STTD-PIC stages (also not shown).
In a particularly advantageous embodiment of the present invention, stages that include a PIC receiver can apply parallel interference cancellation to the pilot signal (or signals) for each transmit antenna, in an analogous fashion to that used for user symbols. This alternative may significantly improve channel estimation.
In another embodiment, the system may also employ receive diversity. FIG. 6 is a simplified schematic drawing illustrating the antenna configuration of a telecommunication system 600 utilizing both transmit and receive diversity according to an embodiment of the present invention. Similar to the embodiment of FIG. 4 , transmit antenna TX 1 and transmit antenna TX 2 are used to achieve transmit diversity for the transmitted signals. In the embodiment of FIG. 6 , however, each of the each of these transmissions is received by both receive antennas RX 1 and RX 2 , creating four separate transmission channels represented as h 11 , h 12 , h 21 , and h 22 . This configuration is said to exhibit 2-2 diversity.
Note that in contrast to the system of FIG. 4 , the two receivers RX 1 and RX 2 are normally located at the same device. There may be many such devices, of course, each receiving the same signal. In one embodiment of the present invention, the transmit diversity signal may be received and processed by devices having a single receive antenna as well as by devices having two (or more) receive antennas.
In the embodiment of FIG. 6 , the signals transmitted by antennas TX 1 and TX 2 are represented as x 1 and x 2 , respectively. The combined signal received at receiver RX 1 (including additive noise v 1 ) is represented as y 1 , and the combined signal received at antenna RX 2 (plus noise v 2 ) as y 2 . In this case, the received signal y is represented as:
y
=
[
y
1
y
2
]
=
[
H
11
H
21
H
12
H
22
]
[
x
1
x
2
]
+
[
v
1
v
2
]
FIG. 7 is a flow chart illustrating a method 700 of receiving a radio signal according to an embodiment of the present invention. Initially, (START), it is presumed that the receiver of FIG. 5 is being utilized; the operation of various other embodiments of the present invention should be apparent, however, in light of this disclosure and the accompanying drawings. The method begins when a radio signal is received at a receive filter (not shown in FIG. 5 ) of the receiver and then downsampled (steps not shown), resulting in a signal represented by a vector y. The downsampled signal y is then received at a first stage of the receiver (step 705 ), where it is processed using a RAKE-STTD receiver (step 710 ). The output û, {circumflex over (d)} (see FIG. 5 ) of the first stage is then received at the STTD-PIC second stage along with the downsampled signal y (step 715 ).
In the STTD-PIC second stage, multiuser interference is identified and subtracted from the signal (step 720 ), and the result provided to an STTD-LMMSE receiver incorporated within the STTD-PIC second stage (step 725 ) and processed to produce output û (2) , {circumflex over (d)} (2) (step 730 ). The STTD-LMMSE chip equalizer (filter) attempts to minimize the mean-squared error between the transmitted chip signal and the received LMMSE filtered signal. This is then received at the STTD-PIC third stage, which is provided with the downsampled signal y as well (step 745 ). There, as in the STTD-PIC second stage, multiuser interference is identified and subtracted from the signal (step 750 ), and the result provided to an STTD-LMMSE receiver incorporated within the STTD-PIC third stage (step 755 ). The third-stage STTD-LMMSE then processes the signal to produce output û (3) , {circumflex over (d)} (3) (step 760 ). This output is then provided to a decoder or, if present, a subsequent STTD-PIC stage or stages (step not shown).
The preferred descriptions are of preferred examples for implementing the invention, and the scope of the invention should not necessarily be limited by this description. Rather, the scope of the present invention is defined by the following claims.
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A receiver, a system, and an associated method, for receiving a radio signal carrying transmitted data that is subject to distortion in the transmission channel. The receiver includes a plurality of stages that perform parallel interference cancellation (PIC) with respect to a received space-time transmit diversity (STTD) signal to establish successively more accurate estimates of the transmitted data, including a receiver first stage being a RAKE-STTD receiver, a second stage including an minimum mean-square error (LMMSE) equalizer, and preferably a third stage also including an LMMSE. Each stage processes the estimates of the transmitted signal provided by the stage preceding it, as well as the received signal, to mitigate or eliminate as much transmission-channel interference as possible and provide a refined estimate for processing by subsequent stages. Improved channel estimation may be achieved by processing the pilot signal in similar fashion as well.
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TECHNICAL FIELD
The present invention relates to fuels for transportation which are derived from natural petroleum, particularly processes for the production of components for refinery blending of transportation fuels which are liquid at ambient conditions. More specifically, it relates to integrated processes which include selective oxygenation of organic compounds in suitable petroleum distillates. The organic compounds are oxygenated in a liquid reaction medium with an oxidizing agent and heterogeneous oxygenation catalyst system which exhibits a capability to enhance the incorporation of oxygen into a mixture of liquid organic compounds to form a mixture comprising hydrocarbons, oxygenated organic compounds, water of reaction, and acidic co-products. The mixture is separated to recover at least a first organic liquid of low density and at least a portions of the catalyst metal, water of reaction and acidic co-products. Advantageously, the organic liquid is washed with an aqueous solution of sodium bicarbonate solution, or other soluble chemical base capable to neutralize and/or remove acidic co-products of oxidation, and recover oxygenated product. Product can be used directly as a blending component, or fractionated, as by further distillation, to provide, for example, more suitable components for blending into diesel fuel. Integrated processes of this invention can also provide their own source oxygenation feedstock as a low-boiling fraction of hydrotreated distillate. Beneficially, integrated processes include selective oxidation of the high-boiling fraction whereby the incorporation of oxygen into the hydrocarbon, sulfur-containing organic and/or nitrogen-containing organic compounds assists by oxidation removal of sulfur and/or nitrogen.
BACKGROUND OF THE INVENTION
It is well known that internal combustion engines have revolutionized transportation following their invention during the last decades of the 19th century. While others, including Benz and Gottleib Wilhelm Daimler, invented and developed engines using electric ignition of fuel such as gasoline, Rudolf C. K. Diesel invented and built the engine named for him which employs compression for auto-ignition of the fuel in order to utilize low-cost organic fuels. Development of improved diesel engines for use in transportation has proceeded hand-in-hand with improvements in diesel fuel compositions. Modern high performance diesel engines demand ever more advanced specification of fuel compositions, but cost remains an important consideration.
At the present time most fuels for transportation are derived from natural petroleum. Indeed, petroleum as yet is the world's main source of hydrocarbons used as fuel and petrochemical feedstock. While compositions of natural petroleum or crude oils are significantly varied, all crudes contain sulfur compounds and most contain nitrogen compounds which may also contain oxygen, but the oxygen content of most crudes is low. Generally, sulfur concentration in crude is less than about 8 percent, with most crudes having sulfur concentrations in the range from about 0.5 to about 1.5 percent. Nitrogen concentration is usually less than 0.2 percent, but it may be as high as 1.6 percent.
Crude oil seldom is used in the form produced at the well, but is converted in oil refineries into a wide range of fuels and petrochemical feedstocks. Typically fuels for transportation are produced by processing and blending of distilled fractions from the crude to meet the particular end use specifications. Because most of the crudes available today in large quantity are high is sulfur, the distilled fractions must be desulfurized to yield products which meet performance specifications and/or environmental standards. Sulfur containing organic compounds in fuels continue to be a major source of environmental pollution. During combustion they are converted to sulfur oxides which, in turn, give rise to sulfur oxyacids and, also, contribute to particulate emissions.
Even in newer, high performance diesel engines combustion of conventional fuel produces smoke in the exhaust. Oxygenated compounds and compounds containing few or no carbon-to-carbon chemical bonds, such as methanol and dimethyl ether, are known to reduce smoke and engine exhaust emissions. However, most such compounds have high vapor pressure and/or are nearly insoluble in diesel fuel, and they have poor ignition quality, as indicated by their cetane numbers. Furthermore, other methods of improving diesel fuels by chemical hydrogenation to reduce their sulfur and aromatics contents, also causes a reduction in fuel lubricity. Diesel fuels of low lubricity may cause excessive wear of fuel injectors and other moving parts which come in contact with the fuel under high pressures.
Distilled fractions used for fuel or a blending component of fuel for use in compression ignition internal combustion engines (Diesel engines) are middle distillates that usually contain from about 1 to 3 percent by weight sulfur. In the past a typical specifications for Diesel fuel was a maximum of 0.5 percent by weight. By 1993 legislation in Europe and United States limited sulfur in Diesel fuel to 0.3 weight percent. By 1996 in Europe and United States, and 1997 in Japan, maximum sulfur in Diesel fuel was reduced to no more than 0.05 weight percent. This world-wide trend must be expected to continue to even lower levels for sulfur.
In one aspect, pending introduction of new emission regulations in California and Federal markets has prompted significant interest in catalytic exhaust treatment. Challenges of applying catalytic emission control for the diesel engine, particularly the heavy-duty diesel engine, are significantly different from the spark ignition internal combustion engine (gasoline engine) due to two factors. First, the conventional TWC catalyst is ineffective in removing NOx emissions from diesel engines, and second, the need for particulate control is significantly higher than with the gasoline engine.
Several exhaust treatment technologies are emerging for control of Diesel engine emissions, and in all sectors the level of sulfur in the fuel affects efficiency of the technology. Sulfur is a catalyst poison that reduces catalytic activity. Furthermore, in the context of catalytic control of Diesel emissions, high fuel sulfur also creates a secondary problem of particulate emission, due to catalytic oxidation of sulfur and reaction with water to form a sulfuric acid mist. This mist is collected as a portion of particulate emissions.
Compression ignition engine emissions differ from those of spark ignition engines due to the different method employed to initiate combustion. Compression ignition requires combustion of fuel droplets in a very lean air/fuel mixture. The combustion process leaves tiny particles of carbon behind and leads to significantly higher particulate emissions than are present in gasoline engines. Due to the lean operation the CO and gaseous hydrocarbon emissions are significantly lower than the gasoline engine. However, significant quantities of unburned hydrocarbon are adsorbed on the carbon particulate. These hydrocarbons are referred to as SOF(soluble organic fraction). Thus, the root cause of health concerns over diesel emissions can be traced to the inhalation of these very small carbon particles containing toxic hydrocarbons deep into the lungs.
While an increase in combustion temperature can reduce particulate, this leads to an increase in NOx emission by the well-known Zeldovitch mechanism. Thus, it becomes necessary to trade off particulate and NOx emissions to meet emissions legislation.
Available evidence strongly suggests that ultra-low sulfur fuel is a significant technology enabler for catalytic treatment of diesel exhaust to control emissions. Fuel sulfur levels of below 15 ppm, likely, are required to achieve particulate levels below 0.01 g/bhp-hr. Such levels would be very compatible with catalyst combinations for exhaust treatment now emerging, which have shown capability to achieve NOx emissions around 0.5 g/bhp-hr. Furthermore, NOx trap systems are extremely sensitive to fuel sulfur and available evidence suggests that they need would sulfur levels below 10 ppm to remain active.
In the face of ever-tightening sulfur specifications in transportation fuels, sulfur removal from petroleum feedstocks and products will become increasingly important in years to come. While legislation on sulfur in diesel fuel in Europe, Japan and the U.S. has recently lowered the specification to 0.05 percent by weight (max.), indications are that future specifications may go far below the current 0.05 percent by weight level.
Conventional hydrodesulfurization (HDS) catalysts can be used to remove a major portion of the sulfur from petroleum distillates for the blending of refinery transportation fuels, but they are not active for removing sulfur from compounds where the sulfur atom is sterically hindered as in multi-ring aromatic sulfur compounds. This is especially true where the sulfur heteroatom is doubly hindered (e.g., 4,6-dimethyldibenzothiophene). Using conventional hydrodesulfurization catalysts at high temperatures would cause yield loss, faster catalyst coking, and product quality deterioration (e.g., color). Using high pressure requires a large capital outlay.
In order to meet stricter specifications in the future, such hindered sulfur compounds will also have to be removed from distillate feedstocks and products. There is a pressing need for economical removal of sulfur from distillates and other hydrocarbon products.
The art is replete with processes said to remove sulfur from distillate feedstocks and products. One known method involves the oxidation of petroleum fractions containing at least a major amount of material boiling above a very high-boiling hydrocarbon materials (petroleum fractrions containing at least a major amount of material boiling above about 550° F.) followed by treating the effluent containing the oxidized compounds at elevated temperatures to form hydrogen sulfide (500° F. to 1350° F.) and/or hydroprocessing to reduce the sulfur content of the hydrocarbon material. See, for example, U.S. Pat. No. 3,847,798 in the name of Jin Sun Yoo and U.S. Pat. No. 5,288,390 in the name of Vincent A. Durante. Such methods have proven to be of only limited utility since only a rather low degree of desulfurization is achieved. In addition, substantial loss of valuable products may result due to cracking and/or coke formation during the practice of these methods. Therefore, it would be advantageous to develop a process which gives an increased degree of desulfuriztion while decreasing cracking or coke formation.
Several different oxygenation methods for improving fuels have been described in the past. For example, U.S. Pat. No. 2,521,698 describes a partial oxidation of hydrocarbon fuels as improving cetane number. This patent suggests that the fuel should have a relatively low aromatic ring content and a high paraffinic content. U.S. Pat. No. 2,912,313 states that an increase in cetane number is obtained by adding both a peroxide and a dihalo compound to middle distillate fuels. U.S. Pat. No. 2,472,152 describes a method for improving the cetane number of middle distillate fractions by the oxidation of saturated cyclic hydrocarbon or naphthenic hydrocarbons in such fractions to form naphthenic peroxides. This patent suggests that the oxidation may be accelerated in the presence of an oil-soluble metal salt as an initiator, but is preferably carried out in the presence of an inorganic base. However, the naphthenic peroxides formed are deleterious gum initiators. Consequently, gum inhibitors such as phenols, cresols and cresyic acids must be added to the oxidized material to reduce or prevent gum formation. These latter compounds are toxic and carcinogenic.
U.S. Pat. No. 4,494,961 in the name of Chaya Venkat and Dennnis E. Walsh relates to improving the cetane number of raw, untreated, highly aromatic, middle distillate fractions having a low hydrogen content by contacting the fraction at a temperature of from 50° C. to 350° C. and under mild oxidizing conditions in the presence of a catalyst which is either (i) an alkaline earth metal permanganate, (ii) an oxide of a metal of Groups IB, IIB, IIIB, IVB, VB, VIB, VIIB or VIIIB of the periodic table, or a mixture of (i) and (ii). European Patent Application 0 252 606 A2 also relates to improving cetane number of a middle distillate fuel fraction which may be hydro-refined by contacting the fraction with oxygen or oxidant, in the presence of catalytic metals such as tin, antimony, lead, bismuth and transition metals of Groups IB, IIB, VB, VIB, VIIB and VIIIB of the periodic table, preferably as an oil-soluble metal salt. The application states that the catalyst selectively oxidizes benzylic carbon atoms in the fuel to ketones.
Recently, U.S. Pat. No. 4,723,963 in the name of William F. Taylor suggests that cetane number is improved by including at least 3 weight percent oxygenated aromatic compounds in middle distillate hydrocarbon fuel boiling in the range of 160° C. to 400° C. This patent states that the oxygenated alkylaromatics and/or oxygenated hydroaromatics are preferably oxygenated at the benzylic carbon proton.
More recently, oxidative desulfurization of middle distillates by reaction with aqueous hydrogen peroxide catalyzed by phosphotungstic acid and tri-n-octylmethylammonium chloride as phase transfer reagent followed by silica adsorption of oxidized sulfur compounds has been described by Collins et al. (Journal of Molecular Catalysis (A): Chemical 117 (1997) 397-403). Collins et al. described the oxidative desulfurization of a winter grade diesel oil which had not undergone hydrotreating. While Collins et al. suggest that the sulfur species resistant to hydrodesulfurization should be susceptible to oxidative desulfurization, the concentrations of such resistant sulfur components in hydrodesulfurized diesel may already be relatively low compared with the diesel oils treated by Collins et al.
U.S. Pat. No. 5,814,109 in the name of Bruce R. Cook, Paul J. Berlowitz and Robert J. Wittenbrink relates to producing Diesel fuel additive, especially via a Fischer-Tropsch hydrocarbon synthesis process, preferably a non-shifting process. In producing the additive, an essentially sulfur free product of these Fischer-Tropsch processes is separated into a high-boiling fraction and a low-boiling fraction, e.g., a fraction boiling below 700° F. The high-boiling of the Fischer-Tropsch reaction product is hydroisomerizied at conditions said to be sufficient to convert the high-boiling fraction to a mixture of paraffins and isoparaffins boiling below 700° F. This mixture is blended with the low-boiling of the Fischer-Tropsch reaction product to recover the diesel additive said to be useful for improving the cetane number or lubricity, or both the cetane number and lubricity, of a mid-distillate, Diesel fuel.
U.S. Pat. No. 6,087,544 in the name of Robert J. Wittenbrink, Darryl P. Klein, Michele S Touvelle, Michel Daage and Paul J. Berlowitz relates to processing a distillate feedstream to produce distillate fuels having a level of sulfur below the distillate feedstream. Such fuels are produced by fractionating a distillate feedstream into a light fraction, which contains only from about 50 to 100 ppm of sulfur, and a heavy fraction. The light fraction is hydrotreated to remove substantially all of the sulfur therein. The desulfurized light fraction, is then blended with one half of the heavy fraction to product a low sulfur distillate fuel, for example 85 percent by weight of desulfurized light fraction and 15 percent by weight of untreated heavy fraction reduced the level of sulfur from 663 ppm to 310 ppm. However, to obtain this low sulfur level only about 85 percent of the distillate feedstream is recovered as a low sulfur distillate fuel product.
There is, therefore, a present need for catalytic processes to prepare oxygenated aromatic compounds in middle distillate hydrocarbon fuel, particularly processes, which do not have the above disadvantages. An improved process should be carried out advantageously in the liquid phase using a suitable oxygenation-promoting catalyst system, preferably an oxygenation catalyst capable of enhancing the incorporation of oxygen into a mixture of organic compounds and/or assisting by oxidation removal of sulfur or nitrogen from a mixture of organic compounds suitable as blending components for refinery transportation fuels liquid at ambient conditions.
This invention is directed to overcoming the problems set forth above in order to provide components for refinery blending of transportation fuels friendly to the environment.
SUMMARY OF THE INVENTION
Economical processes are provided for production of components for refinery blending of transportation fuels by integrated processes which include selective oxygenation of organic compounds in suitable petroleum distillates, preferably a hydrotreated distillate. Integrated processes of this invention advantageously also provide their own source of oxygenation feedstock as a low-boiling fraction of hydrotreated distillate. Beneficially, integrated processes include selective oxidation of the high-boiling fraction whereby the incorporation of oxygen into hydrocarbon, sulfur-containing organic and/or nitrogen-containing organic compounds assists by oxidation removal of sulfur and/or nitrogen.
This invention contemplates the treatment of various type hydrocarbon materials, especially hydrocarbon oils of petroleum origin which contain sulfur. In general, the sulfur contents of the oils are in excess of 1 percent.
One aspect of this invention provides a process for production of refinery transportation fuel or blending components for refinery transportation fuel, which process comprises: providing organic feedstock comprising a mixture of organic compounds derived from natural petroleum, the mixture having a gravity ranging from about 10° API to about 75° API; contacting the organic feedstock with an oxidizing agent and heterogeneous oxygenation catalyst system which exhibits a capability to enhance the incorporation of oxygen into a mixture of liquid organic compounds, while maintaining the reaction medium substantially free of halogen and/or halogen-containing compounds, to form a liquid mixture comprising hydrocarbons, oxygenated organic compounds, water of reaction, and acidic co-products; and separating from the reaction medium at least a first organic liquid of low density comprising hydrocarbons, oxygenated organic compounds and acidic co-products, and at least portions of the heterogeneous oxygenation catalyst system, water of reaction and acidic co-products.
In one aspect, this invention provides a process wherein the organic feedstock comprises sulfur-containing and/or nitrogen-containing organic compounds one or more of which are oxidized in the liquid reaction medium. Advantageously, at least a portion of the oxidized sulfur-containing and/or nitrogen-containing organic compounds are sorbed onto the heterogeneous oxygenation catalyst. Typically, a second separated liquid is an aqueous solution containing at least a portion of the oxidized sulfur-containing and/or nitrogen-containing organic compounds.
Beneficially, processes according to the invention further comprise contacting the separated organic liquid with a neutralizing agent and recovering a product having a low content of acidic co-products.
Processes of the present invention advantageously include catalytic hydrotreating of the oxidation feedstock to form hydrogen sulfide which may be separated as a gas from the liquid feedstock, collected on a solid sorbent, and/or by washing with aqueous liquid. In a preferred aspect of the invention, the all or at least a portion of the organic feedstock is a product of a hydrotreating process for petroleum distillates consisting essentially of material boiling between about 50° C. and about 425° C. which hydrotreating process includes reacting the petroleum distillate with a source of hydrogen at hydrogenation conditions in the presence of a hydrogenation catalyst to assist by hydrogenation removal of sulfur and/or nitrogen from the hydrotreated petroleum distillate.
In another aspect, this invention provides a process for selective oxygenation of organic compounds wherein all or at least a portion of the organic feedstock is a product of a hydrotreating process for petroleum distillates consisting essentially of material boiling between about 50° C. and about 425° C. The hydrotreating process includes reacting the petroleum distillate with a source of hydrogen at hydrogenation conditions in the presence of a hydrogenation catalyst to assist by hydrogenation removal of sulfur and/or nitrogen from the hydrotreated petroleum distillate. Generally, useful hydrogenation catalysts comprise at least one active metal, selected from the group consisting of the d-transition elements in the Periodic Table, each incorporated onto an inert support in an amount of from about 0.1 percent to about 30 percent by weight of the total catalyst. Suitable active metals include the d-transition elements in the Periodic Table elements having atomic number in from 21 to 30, 39 to 48, and 72 to 78.
Hydrogenation catalysts beneficially contain a combination of metals. Preferred are hydrogenation catalysts containing at least two metals selected from the group consisting of cobalt, nickel, molybdenum and tungsten. More preferably, co-metals are cobalt and molybdenum or nickel and molybdenum. Advantageously, the hydrogenation catalyst comprises at least two active metals, each incorporated onto a metal oxide support, such as alumina in an amount of from about 0.1 percent to about 20 percent by weight of the total catalyst.
In one aspect, this invention provides for the production of refinery transportation fuel or blending components for refinery transportation fuel wherein the hydrotreating process further comprises partitioning of the hydrotreated petroleum distillate by distillation to provide at least one low-boiling liquid consisting of a sulfur-lean, mono-aromatic-rich fraction, and a high-boiling liquid consisting of a sulfur-rich, mono-aromatic-lean fraction, and wherein the organic feedstock is predominantly the low-boiling liquid.
The heterogeneous oxygenation catalyst system for use according to the invention comprises an active metal selected from the group consisting of vanadium, chromium, molybdenum, tungsten manganese, iron, cobalt, nickel, palladium, platinum, copper, silver, or mixture thereof. The metal or metals may be employed in elemental, combined, or ionic form. Preferably the form of the metal is as metal oxide, mixed metal oxide, and/or basic salts of the metal or mixed metal oxide. Advantageously the heterogeneous oxygenation catalyst system further comprises an alkali metal, alkaline earth metal and/or a member of group V of the periodic table. The alkali metal is any of the univalent mostly basic metals of group I of the periodic table comprising lithium, sodium, potassium, rubidium, cesium and francium, preferably potassium, and/or cesium. The alkali earth metal is any of the bivalent strongly basic metals comprising calcium, strontium and barium and magnesium, preferably magnesium. Useful group V metals are phosphorus, arsenic, antimony, and bismuth, preferably phosphorus and/or bismuth. Beneficially, at least a portion of the catalyst system is recovered, and all or a portion of the recovered catalyst system is injected into the liquid reaction medium.
In one aspect of the invention, the heterogeneous oxygenation catalyst system for selective oxygenation of organic compounds according to the invention comprises a particulate oxygenation catalyst containing from about 1 percent to about 30 percent chromium as oxide and from about 0.1 percent to about 5 percent platinum on a solid support. Preferably, the support comprises gamma alumina (γ-Al 2 O 3 ).
Preferably, the heterogeneous oxygenation catalyst system for selective oxygenation of organic compounds according to the invention comprises a source of a particulate form of chromium molybdate or bismuth molybdate and optionally magnesium. In another preferred aspect of the invention the heterogeneous oxygenation catalyst system for selective oxygenation of organic compounds according to the invention comprises from about 0.1 percent to about 1.5 percent of a catalyst represented by formula Na 2 Cr 2 O 7 on support comprising gamma alumina.
In another aspect of this invention there is provided a process for the production of refinery transportation fuel or blending components for refinery transportation fuel, which process comprises: partitioning by distillation an organic feedstock comprising a mixture of organic compounds derived from natural petroleum, the mixture having a gravity ranging from about 10° API to about 75° API, preferably having a gravity ranging from about 15° API to about 50° API, to provide at least one low-boiling organic part consisting of a sulfur-lean, mono-aromatic-rich fraction, and a high-boiling organic part consisting of a sulfur-rich, mono-aromatic-lean fraction; contacting a gaseous source of dioxygen with at least a portion of the low-boiling organic part in a liquid reaction medium containing a heterogeneous oxygenation catalyst system which exhibits a capability to enhance the incorporation of oxygen into a mixture of liquid organic compounds while maintaining the reaction medium substantially free of halogen and/or halogen-containing compounds, to form a liquid mixture comprising hydrocarbons, oxygenated organic compounds, water of reaction, and acidic co-products; and, while maintaining the liquid reaction medium substantially free of halogen and/or halogen-containing compounds, to form a mixture comprising hydrocarbons, oxygenated organic compounds, water of reaction, and acidic co-products; separating from the mixture at least a first organic liquid of low density comprising hydrocarbons, oxygenated organic compounds and acidic co-products and at least portions of the catalyst metal, water of reaction and acidic co-products; and contacting all or a portion of the separated organic liquid with a neutralizing agent thereby recovering a low-boiling oxygenated product having a low content of acidic co-products.
Beneficially, at least a portion of the separated organic liquid is contacted with an aqueous solution of a chemical base, and the recovered oxygenated product exhibits a total acid number of less than about 20 mg KOH/g. The recovered oxygenated product advantageously exhibits a total acid number of less than about 10 mg KOH/g. More preferred are oxygenated products which exhibit a total acid number of less than about 5, and most preferred less than about 1. Preferably, the chemical base is a compound selected from the group consisting of sodium, potassium, barium, calcium and magnesium in the form of hydroxide, carbonate or bicarbonate.
In one preferred aspect of the invention, all or at least a potion of the organic feedstock is a product of a process for hydrogenation of a petroleum distillate consisting essentially of material boiling between about 50° C. and about 425° C. which hydrogenation process includes reacting the petroleum distillate with a source of hydrogen at hydrogenation conditions in the presence of a hydrogenation catalyst to assist by hydrogenation removal of sulfur and/or nitrogen from the hydrotreated petroleum distillate.
In another aspect this invention provides an integrate process for the production of refinery transportation fuel or blending components for refinery transportation fuel, which process comprises: partitioning by distillation an organic feedstock comprising a mixture of organic compounds derived from natural petroleum, the mixture consisting essentially of material boiling between about 75° C. and about 425° C. to provide at least one low-boiling organic part consisting of a sulfur-lean, mono-aromatic-rich fraction, and a high-boiling organic part consisting of a sulfur-rich, mono-aromatic-lean fraction; contacting a gaseous source of dioxygen with at least a portion of the low-boiling organic part in a liquid reaction medium containing a heterogeneous oxygenation catalyst system which exhibits a capability to enhance the incorporation of oxygen into a mixture of liquid organic compounds while maintaining the reaction medium substantially free of halogen and/or halogen-containing compounds, to form a liquid mixture comprising hydrocarbons, oxygenated organic compounds, water of reaction, and acidic co-products; and, while maintaining the liquid reaction medium substantially free of halogen and/or halogen-containing compounds, to form a mixture comprising hydrocarbons, oxygenated organic compounds, water of reaction, and acidic co-products; separating from the mixture at least a first organic liquid of low density comprising hydrocarbons, oxygenated organic compounds and acidic co-products and at least portions of the catalyst metal, water of reaction and acidic co-products; and contacting all or a portion of the separated organic liquid with a neutralizing agent and recovering a low-boiling oxygenated product having a low content of acidic co-products. The integrated process further comprises contacting the high-boiling organic part with an immiscible phase comprising at least one organic peracid or precursors of organic peracid in a liquid reaction mixture maintained substantially free of catalytic active metals and/or active metal-containing compounds and under conditions suitable for oxidation of one or more of the sulfur-containing and/or nitrogen-containing organic compounds; separating at least a portion of the immiscible peracid-containing phase from the oxidized phase of the reaction mixture; and contacting the oxidized phase of the reaction mixture with a solid sorbent, an ion exchange resin, and/or a suitable immiscible liquid containing a solvent or a soluble basic chemical compound, to obtain a high-boiling product containing less sulfur and/or less nitrogen than the high-boiling fraction.
Generally for use in this invention, the immiscible phase is formed by admixing a source of hydrogen peroxide and/or alkylhydroperoxide, an aliphatic monocarboxylic acid of 2 to about 6 carbon atoms, and water. Advantageously, the immiscible phase is formed by admixing hydrogen peroxide, acetic acid, and water. Advantageously, at least a portion of the separated peracid-containing phase is recycled to the reaction mixture. Preferably, the conditions of oxidation include temperatures in a range upward from about 25° C. to about 250° C. and sufficient pressure to maintain the reaction mixture substantially in a liquid phase.
Sulfur-containing organic compounds in the oxidation feedstock include compounds in which a sulfur atom is sterically hindered, as for example in multi-ring aromatic sulfur compounds. Typically, the sulfur-containing organic compounds include at least sulfides, heteroaromatic sulfides, and/or compounds selected from the group consisting of substituted benzothiophenes and dibenzothiophenes.
Beneficially, the instant oxidation process is very selective in that selected organic peracids in a liquid phase reaction mixture maintained substantially free of catalytic active metals and/or active metal-containing compounds, preferentially oxidize compounds in which a sulfur atom is sterically hindered rather than aromatic hydrocarbons.
According the present invention, suitable distillate fractions are preferably hydrodesulfureized before being selectively oxidized, and more preferably using a facility capable of providing effluents of at least one low-boiling fraction and one high-boiling fraction.
This invention provides a process wherein all or at least a potion of the oxidation feedstock is a product of a process for hydrogenation of a petroleum distillate consisting essentially of material boiling between about 50° C. and about 425° C. Preferably the petroleum distillate consisting essentially of material boiling between about 150° C. and about 400° C., and more preferably boiling between about 175° C. and about 375° C. According to a further aspect of this invention, the hydrogenation process includes reacting the petroleum distillate with a source of hydrogen at hydrogenation conditions in the presence of a hydrogenation catalyst to assist by hydrogenation removal of sulfur and/or nitrogen from the hydrotreated petroleum distillate.
Advantageously, the hydrogenation catalyst comprises at least one active metal, each incorporated onto an inert support in an amount of from about 0.1 percent to about 2.0 percent by weight of the total catalyst. Preferably, the active metal is selected from the group consisting of palladium and platinum, and/or the support is mordenite.
According to a further aspect of this invention, the hydrogenation process includes partitioning of the hydrotreated petroleum distillate by distillation to provide at least one low-boiling blending component consisting of a sulfur-lean, mono-aromatic-rich fraction, and a high-boiling fraction consisting of a sulfur-rich, mono-aromatic-lean fraction. Advantageously, the oxygenation feedstock consists essentially of the high-boiling fraction. Typically, an integrated process of this invention further comprises blending at least a portion of the low-boiling fraction with the acid-free product to obtain components for refinery blending of transportation fuel friendly to the environment.
Where the oxidation feedstock is a high-boiling distillate fraction derived from hydrogenation of a refinery stream, the refinery stream consists essentially of material boiling between about 200° C. and about 425° C. Preferably the refinery stream consisting essentially of material boiling between about 250° C. and about 400° C., and more preferably boiling between about 275° C. and about 375° C.
In other aspects of this invention, continuous processes are provided wherein the step of contacting the oxidation feedstock and immiscible phase is carried out continuously with counter-current, cross-current, or co-current flow of the two phases.
Where the oxidation feedstock is a high-boiling distillate fraction derived from hydrogenation of a refinery stream, the refinery stream consists essentially of material boiling between about 200° C. and about 425° C. Preferably the refinery stream consisting essentially of material boiling between about 250° C. and about 400° C., and more preferably boiling between about 275° C. and about 375° C.
Preferably, the immiscible peracid-containing phase is an aqueous liquid formed by admixing, water, a source of acetic acid, and a source of hydrogen peroxide in amounts which provide at least one mole acetic acid for each mole of and hydrogen peroxide. Beneficially, at least a portion of the separated peracid-containing phase is recycled to the reaction mixture.
In another aspect of this invention the treating of recovered organic phase includes use of at least one immiscible liquid comprising an aqueous solution of a soluble basic chemical compound selected from the group consisting of sodium, potassium, barium, calcium and magnesium in the form of hydroxide, carbonate or bicarbonate. Particularly useful are aqueous solution of sodium hydroxide or bicarbonate.
In one aspect of this invention the treating of the recovered organic phase includes use of at least one solid sorbent comprising alumina.
In another aspect of this invention the treating of recovered organic phase includes use of at least one immiscible liquid comprising a solvent having a dielectric constant suitable to selectively extract oxidized sulfur-containing and/or nitrogen-containing organic compounds. Advantageously, the solvent has a dielectric constant in a range from about 24 to about 80. Useful solvents include mono- and dihydric alcohols of 2 to about 6 carbon atoms, preferably methanol, ethanol, propanol, ethylene glycol, propylene glycol, butylene glycol and aqueous solutions thereof. Particularly useful are immiscible liquids wherein the solvent comprises a compound that is selected from the group consisting of water, methanol, ethanol and mixtures thereof.
In yet another aspect of this invention the soluble basic chemical compound is sodium bicarbonate, and the treating of the organic phase further comprises subsequent use of at least one other immiscible liquid comprising methanol.
In other aspects of this invention, continuous processes are provided wherein the step of contacting the oxidation feedstock and immiscible phase is carried out continuously with counter-current, cross-current, or co-current flow of the two phases.
In one aspect of this invention, the recovered organic phase of the reaction mixture is contacted sequentially with (i) an ion exchange resin and (ii) a heterogeneous sorbent to obtain a product having a suitable total acid number.
For a more complete understanding of the present invention, reference should now be made to the embodiments illustrated in greater detail in the accompanying drawing and described below by way of examples of the invention.
BRIEF DESCRIPTION OF THE DRAWING
The drawings are schematic flow diagrams depicting preferred aspects of the present invention for continuous production of components for the blending of transportation fuels which are liquid at ambient conditions. Elements of the invention in the schematic flow diagram of FIG. 1 include oxygenating an organic feedstock with dioxygen in a liquid reaction medium containing a heterogeneous oxygenation catalyst system which exhibits a capability to enhance the incorporation of oxygen into a mixture of liquid organic compounds while maintaining the reaction medium substantially free of halogen and/or halogen-containing compounds, to form a liquid mixture comprising hydrocarbons, oxygenated organic compounds, water of reaction, and acidic co-products. The mixture is separated to recover at least a first organic liquid of low density comprising hydrocarbons, oxygenated organic compounds and acidic co-products and at least portions of the catalyst metal, water of reaction and acidic co-products. The organic liquid is washed with an aqueous solution of sodium bicarbonate solution, or other soluble chemical base capable to neutralize and/or remove acidic co-products of oxidation, and recover oxygenated product.
Elements of the invention in the schematic flow diagram of FIG. 2 include hydrotreating a petroleum distillate with a source of dihydrogen (molecular hydrogen), and fractionating the hydrotreated petroleum to provide a low-boiling blending component consisting of a sulfur-lean, mono-aromatic-rich fraction, and a high-boiling oxidation feedstock consisting of a sulfur-rich, mono-aromatic-lean fraction. This high-boiling oxidation feedstock is contacted with an immiscible phase comprising at least one organic peracid or precursors of organic peracid, in a liquid reaction mixture maintained substantially free of catalytic active metals and/or active metal-containing compounds and under conditions suitable for oxidation of one or more of the sulfur-containing and/or nitrogen-containing organic compounds. Thereafter, the immiscible phases are separated by gravity to recover a portion of the acid-containing phase for recycle. The other portion of the reaction mixture is contacted with a solid sorbent and/or an ion exchange resin to recover a mixture of organic products containing less sulfur and/or less nitrogen than the oxidation feedstock.
GENERAL DESCRIPTION
For the purpose of the present invention, the term “heterogeneous oxygenation catalyst” means any composition solid at the conditions of oxygenation which enhances incorporation of oxygen into organic compounds and/or assists by oxidation removal of sulfur or nitrogen from a mixture of organic compounds for refinery blending of transportation fuels which are liquid at ambient conditions.
Useful heterogeneous oxygenation catalyst systems are based upon a variety of supported or unsupported transition metal compounds active for liquid phase oxidation of organic compounds comprising the low-boiling fraction. Generally, oxygenation catalyst systems comprise at least one active metal, selected from the group consisting of the d-transition elements in the Periodic Table, e.g., active metals are selected from the d-transition elements in the Periodic Table elements having atomic number in from 21 to 30, 39 to 48, and 72 to 78. Advantageously, one or more active metal is each incorporated onto an inert support in an amount of from about 0.01 percent to about 30 percent by weight of the total catalyst, preferably from about 0.1 percent to about 15 percent, and more preferably from about 0.1 percent to about 10 percent for best results.
Oxygenation catalysts beneficially contain a combination of active metals are selected from the d-transition elements in the Periodic Table elements and optionally a metal of Groups IV and V.
A preferred class of hydrogenation catalysts containing at least two metals selected from the group consisting of cobalt, nickel, molybdenum and tungsten. More preferably, co-metals are cobalt and molybdenum or nickel and molybdenum. Advantageously, the hydrogenation catalyst comprises at least two active metals, each incorporated onto a metal oxide support, such as alumina in an amount of from about 0.1 percent to about 20 percent by weight of the total catalyst. Other preferred heterogeneous oxygenation catalyst systems contain chromium molybdate and/or bismuth molybdate which optionally can be promoted with magnesium, CuO/SiO 2 , CrFeBiMoO, (chrome molybdate/iron promoted with magnesium) and MgFeBiMoO, (bismuth molybdate/iron promoted with magnesium).
A particularly preferred heterogeneous oxygenation catalyst system includes from about 0.1 percent to about 10 percent platinum and from about 5 percent to about 30 percent chromium as oxide on γ-Al 2 O 3 (CrOPt/Al 2 O 3 ), and more preferably from about 1 percent to about 5 percent platinum and from about 15 percent to about 20 percent chromium as oxide on γ-Al 2 O 3 . Another preferred heterogeneous oxygenation catalyst system contains from about 0.01 percent to about 5 percent Na 2 Cr 2 O 7 on γ-Al 2 O 3 ), and more preferably from about 0.1 percent to about 3 percent Na 2 Cr 2 O 7 on γ-Al 2 O 3 .
Suitable feedstocks generally comprise most refinery streams consisting substantially of hydrocarbon compounds which are liquid at ambient conditions. Suitable oxidation feedstock generally has an API gravity ranging from about 10° API to about 100° API, preferably from about 10° API to about 75° API, and more preferably from about 15° API to about 50° API for best results. These streams include, but are not limited to, fluid catalytic process naphtha, fluid or delayed process naphtha, light virgin naphtha, hydrocracker naphtha, hydrotreating process naphthas, alkylate, isomerate, catalytic reformate, and aromatic derivatives of these streams such benzene, toluene, xylene, and combinations thereof. Catalytic reformate and catalytic cracking process naphthas can often be split into narrower boiling range streams such as light and heavy catalytic naphthas and light and heavy catalytic reformate, which can be specifically customized for use as a feedstock in accordance with the present invention. The preferred streams are light virgin naphtha, catalytic cracking naphthas including light and heavy catalytic cracking unit naphtha, catalytic reformate including light and heavy catalytic reformate and derivatives of such refinery hydrocarbon streams.
Suitable oxidation feedstocks generally include refinery distillate steams boiling at a temperature range from about 50° C. to about 425° C., preferably 150° C. to about 400° C., and more preferably between about 175° C. and about 375° C. at atmospheric pressure for best results. These streams include, but are not limited to, virgin light middle distillate, virgin heavy middle distillate, fluid catalytic cracking process light catalytic cycle oil, coker still distillate, hydrocracker distillate, and the collective and individually hydrotreated embodiments of these streams. The preferred streams are the collective and individually hydrotreated embodiments of fluid catalytic cracking process light catalytic cycle oil, coker still distillate, and hydrocracker distillate.
It is also anticipated that one or more of the above distillate steams can be combined for use as oxidation feedstock. In many cases performance of the refinery transportation fuel or blending components for refinery transportation fuel obtained from the various alternative feedstocks may be comparable. In these cases, logistics such as the volume availability of a stream, location of the nearest connection and short term economics may be determinative as to what stream is utilized.
Typically, sulfur compounds in petroleum fractions are relatively non-polar, heteroaromatic sulfides such as substituted benzothiophenes and dibenzothiophenes. At first blush it might appear that heteroaromatic sulfur compounds could be selectively extracted based on some characteristic attributed only these heteroaromatics. Even though the sulfur atom in these compounds has two, non-bonding pairs of electrons which would classify them as a Lewis base, this characteristic is still not sufficient for them to be extracted by a Lewis acid. In other words, selectively extraction of heteroaromatic sulfur compounds to achieve lower levels of sulfur requires greater difference in polarity between the sulfides and the hydrocarbons.
By means of liquid phase oxidation according to this invention it is possible to selectively convert these sulfides into, more polar, Lewis basic, oxygenated sulfur compounds such as sulfoxides and sulfones. Compounds such as dimethylsulfide are very non-polar molecules. Accordingly, by selectively oxidizing heteroaromatic sulfides such as benzo- and dibenzothiophene found in a refinery streams, processes of the invention are able to selectively bring about a higher polarity characteristic to these heteroaromatic compounds. Where the polarity of these unwanted sulfur compounds is increased by means of liquid phase oxidation according to this invention, they can be selectively extracted by a polar solvent and/or a Lewis acid sorbent while the bulk of the hydrocarbon stream is unaffected.
Other compounds which also have non-bonding pairs of electrons include amines. Heteroaromatic amines are also found in the same stream that the above sulfides are found. Amines are more basic than sulfides. The lone pair of electrons functions as a Bronstad-Lowry base (proton acceptor) as well as a Lewis base (electron-donor). This pair of electrons on the atom makes it vulnerable to oxidation in manners similar to sulfides.
During contacting the oxidation feedstock with an immiscible phase comprising at least one organic peracid or precursors of organic peracid in the liquid phase, conditions suitable for oxidation include any pressure and temperature upward from about 10° C. at which the reaction proceeds. Preferred temperatures are between about 25° C. and about 250° C., with between about 50° and about 150° C. being more preferred. The most preferred temperatures are between about 115° C. and about 125° C.
As disclosed herein oxidation feedstock is contacted with an immiscible phase comprising at least one organic peracid which contains the —OOH substructure or precursors of organic peracid, and the liquid reaction mixture is maintained substantially free of catalytic active metals and/or active metal-containing compounds and under conditions suitable for oxidation of one or more of the sulfur-containing and/or nitrogen-containing organic compounds. Organic peracids for use in this invention are preferably made from a combination of hydrogen peroxide and a carboxylic acid.
With respect to the organic peracids the carbonyl carbon is attached to hydrogen or a hydrocarbon radical. In general such hydrocarbon radical contains from 1 to about 12 carbon atoms, preferably from about 1 to about 8 carbon atoms. More preferably, the organic peracid is selected from the group consisting of performic acid, peracetic acid, trichloroacetic acid, perbenzoic acid and perphpthalic acid or precursors thereof. For best results processes of the present invention employ peracetic acid or precursors of peracetic acid.
Broadly, the appropriate amount of organic peracid used herein is the stoichiometric amount necessary for oxidation of one or more of the sulfur-containing and/or nitrogen-containing organic compounds in the oxidation feedstock and is readily determined by direct experimentation with a selected feedstock. With a higher concentration of organic peracid, the selectivity generally tends to favor the more highly oxidized sulfone which beneficially is even more polar than the sulfoxide.
Applicants believe the oxidation reaction involves rapid reaction of organic peracid with the divalent sulfur atom by a concerted, non-radical mechanism whereby an oxygen atom is actually donated to the sulfur atom. As stated previously, in the presence of more peracid, the sulfoxide is further converted to the sulfone, presumably by the same mechanism. Similarly, it is expected that the nitrogen atom of an amino is oxidized in the same manner by hydroperoxy compounds.
The statement that oxidation according to the invention in the liquid reaction mixture comprises a step whereby an oxygen atom is donated to the divalent sulfur atom is not to be taken to imply that processes according to the invention actually proceeds via such a reaction mechanism.
By contacting oxidation feedstock with a peracid-containing immiscible phase in a liquid reaction mixture maintained substantially free of catalytic active metals and/or active metal-containing compounds, the tightly substituted sulfides are oxidized into their corresponding sulfoxides and sulfones with negligible if any co-oxidation of mononuclear aromatics. These oxidation products due to their high polarity, can be readily removed by separation techniques such as adsorption and extraction. The high selectivity of the oxidants, coupled with the small amount of tightly substituted sulfides in hydrotreated streams, makes the instant invention a particularly effective deep desulfurization means with minimum yield loss. The yield loss corresponds to the amount of tightly substituted sulfides oxidized. Since the amount of tightly substituted sulfides present in a hydrotreated crude is rather small, the yield loss is correspondingly small.
Broadly, the liquid phase oxidation reactions are rather mild and can even be carried out at temperatures as low as room temperature. More particularly, the liquid phase oxidation will be conducted under any conditions capable of converting the tightly substituted sulfides into their corresponding sulfoxides and sulfones at reasonable rates.
In accordance with this invention conditions of the liquid mixture suitable for oxidation during the contacting the oxidation feedstock with the organic peracid-containing immiscible phase include any pressure at which the desired oxidation reactions proceed. Typically, temperatures upward from about 10° C. are suitable. Preferred temperatures are between about 25° C. and about 250° C., with temperatures between about 50° and about 150° C. being more preferred. Most preferred temperatures are between about 115° C. and about 125° C.
Integrated processes of the invention can include one or more selective separation steps using solid sorbents capable of removing sulfoxides and sulfones. Non-limiting examples of such sorbents, commonly known to the skilled artisan, include activated carbons, activated bauxite, activated clay, activated coke, alumina, and silica gel. The oxidized sulfur containing hydrocarbon material is contacted with solid sorbent for a time sufficient to reduce the sulfur content of the hydrocarbon phase.
Integrated processes of the invention can include one or more selective separation steps using an immiscible solvent having a dielectric constant suitable to selectively extract oxidized sulfur-containing and/or nitrogen-containing organic compounds. Preferably the present invention uses an solvent which exhibits a dielectric constant in a range from about 24 to about 80. For best results processes of the present invention employ solvent comprises a compound is selected from the group consisting of water, methanol, ethanol and mixtures thereof.
Integrated processes of the invention can include one or more selective separation steps using an immiscible liquid containing a soluble basic chemical compound. The oxidized sulfur containing hydrocarbon material is contacted with the solution of chemical base for a time sufficient.
Generally, the suitable basic compounds include ammonia or any hydroxide, carbonate or bicarbonate of an element selected from Group I, II, and/or III of the periodic table, although calcined dolomitic materials and alkalized aluminas can be used. In addition mixtures of different bases can be utilized. Preferably the basic compound is a hydroxide, carbonate or bicarbonate of an element selected from Group I and/or II element. More preferably, the basic compound is selected from the group consisting of sodium, potassium, barium, calcium and magnesium hydroxide, carbonate or bicarbonate. For best results processes of the present invention employ an aqueous solvent containing an alkali metal hydroxide, preferably selected from the group consisting of sodium, potassium, barium, calcium and magnesium hydroxide. In general, an aqueous solution of the base hydroxide at a concentration on a mole basis of from about 1 mole of base to 1 mole of sulfur up to about 4 moles, of base per mole of sulfur is suitable.
In carrying out a sulfur separation step according to this invention, pressures of near atmospheric and higher may be suitable. For example, pressures up to 100 atmosphere can be used.
Processes of the present invention advantageously include catalytic hydrodesulfurization of the oxidation feedstock to form hydrogen sulfide which may be separated as a gas from the liquid feedstock, collected on a solid sorbent, and/or by washing with aqueous liquid. Where the oxidation feedstock is a product of a process for hydrogenation of a petroleum distillate to facilitate removal of sulfur and/or nitrogen from the hydrotreated petroleum distillate, the amount of peracid necessary for the instant invention is the stoichiometric amount necessary to oxidize the tightly substituted sulfides contained in the hydrotreated stream being treated in accordance herewith. Preferably an amount which will oxidize all of the tightly substituted sulfides will be used.
Useful distillate fractions for hydrogenation in the present invention consists essentially of any one, several, or all refinery streams boiling in a range from about 50° C. to about 425° C., preferably 150° C. to about 400° C., and more preferably between about 175° C. and about 375° C. at atmospheric pressure. For the purpose of the present invention, the term “consisting essentially of” is defined as at least 95 percent of the feedstock by volume. The lighter hydrocarbon components in the distillate product are generally more profitably recovered to gasoline and the presence of these lower boiling materials in distillate fuels is often constrained by distillate fuel flash point specifications. Heavier hydrocarbon components boiling above 400° C. are generally more profitably processed as FCC Feed and converted to gasoline. The presence of heavy hydrocarbon components in distillate fuels is further constrained by distillate fuel end point specifications.
The distillate fractions for hydrogenation in the present invention can comprise high and low sulfur virgin distillates derived from high- and low-sulfur crudes, coker distillates, catalytic cracker light and heavy catalytic cycle oils, and distillate boiling range products from hydrocracker and resid hydrotreater facilities. Generally, coker distillate and the light and heavy catalytic cycle oils are the most highly aromatic feedstock components, ranging as high as 80 percent by weight. The majority of coker distillate and cycle oil aromatics are present as mono-aromatics and di-aromatics with a smaller portion present as tri-aromatics. Virgin stocks such as high and low sulfur virgin distillates are lower in aromatics content ranging as high as 20 percent by weight aromatics. Generally, the aromatics content of a combined hydrogenation facility feedstock will range from about 5 percent by weight to about 80 percent by weight, more typically from about 10 percent by weight to about 70 percent by weight, and most typically from about 20 percent by weight to about 60 percent by weight. In a distillate hydrogenation facility with limited operating capacity, it is generally profitable to process feedstocks in order of highest aromaticity, since catalytic processes often proceed to equilibrium product aromatics concentrations at sufficient space velocity. In this manner, maximum distillate pool dearomatization is generally achieved.
Sulfur concentration in distillate fractions for hydrogenation in the present invention is generally a function of the high and low sulfur crude mix, the hydrogenation capacity of a refinery per barrel of crude capacity, and the alternative dispositions of distillate hydrogenation feedstock components. The higher sulfur distillate feedstock components are generally virgin distillates derived from high sulfur crude, coker distillates, and catalytic cycle oils from fluid catalytic cracking units processing relatively higher sulfur feedstocks. These distillate feedstock components can range as high as 2 percent by weight elemental sulfur but generally range from about 0.1 percent by weight to about 0.9 percent by weight elemental sulfur. Where a hydrogenation facility is a two-stage process having a first-stage denitrogenation and desulfurization zone and a second-stage dearomatization zone, the dearomatization zone feedstock sulfur content can range from about 100 ppm to about 0.9 percent by weight or as low as from about 10 ppm to about 0.9 percent by weight elemental sulfur.
Nitrogen content of distillate fractions for hydrogenation in the present invention is also generally a function of the nitrogen content of the crude oil, the hydrogenation capacity of a refinery per barrel of crude capacity, and the alternative dispositions of distillate hydrogenation feedstock components. The higher nitrogen distillate feedstocks are generally coker distillate and the catalytic cycle oils. These distillate feedstock components can have total nitrogen concentrations ranging as high as 2000 ppm, but generally range from about 5 ppm to about 900 ppm.
The catalytic hydrogenation process may be carried out under relatively mild conditions in a fixed, moving fluidized or ebullient bed of catalyst. Preferably a fixed bed of catalyst is used under conditions such that relatively long periods elapse before regeneration becomes necessary, for example a an average reaction zone temperature of from about 200° C. to about 450° C., preferably from about 250° C. to about 400° C., and most preferably from about 275° C. to about 350° C. for best results, and at a pressure within the range of from about 6 to about 160 atmospheres.
A particularly preferred pressure range within which the hydrogenation provides extremely good sulfur removal while minimizing the amount of pressure and hydrogen required for the hydrodesulfurization step are pressures within the range of 20 to 60 atmospheres, more preferably from about 25 to 40 atmospheres.
According the present invention, suitable distillate fractions are preferably hydrodesulfureized before being selectively oxidized, and more preferably using a facility capable of providing effluents of at least one low-boiling fraction and one high-boiling fraction.
Where the particular hydrogenation facility is a two-stage process, the first stage is often designed to desulfurize and denitrogenate, and the second stage is designed to dearomatize. In these operations, the feedstocks entering the dearomatization stage are substantially lower in nitrogen and sulfur content and can be lower in aromatics content than the feedstocks entering the hydrogenation facility.
Generally, the hydrogenation process useful in the present invention begins with a distillate fraction preheating step. The distillate fraction is preheated in feed/effluent heat exchangers prior to entering a furnace for final preheating to a targeted reaction zone inlet temperature. The distillate fraction can be contacted with a hydrogen stream prior to, during, and/or after preheating. The hydrogen-containing stream can also be added in the hydrogenation reaction zone of a single-stage hydrogenation process or in either the first or second stage of a two-stage hydrogenation process.
The hydrogen stream can be pure hydrogen or can be in admixture with diluents such as hydrocarbon, carbon monoxide, carbon dioxide, nitrogen, water, sulfur compounds, and the like. The hydrogen stream purify should be at least about 50 percent by volume hydrogen, preferably at least about 65 percent by volume hydrogen, and more preferably at least about 75 percent by volume hydrogen for best results. Hydrogen can be supplied from a hydrogen plant, a catalytic reforming facility or other hydrogen producing process.
The reaction zone can consist of one or more fixed bed reactors containing the same or different catalysts. Two-stage processes can be designed with at least one fixed bed reactor for desulfurization and denitrogenation, and at least one fixed bed reactor for dearomatization. A fixed bed reactor can also comprise a plurality of catalyst beds. The plurality of catalyst beds in a single fixed bed reactor can also comprise the same or different catalysts. Where the catalysts are different in a multi-bed fixed bed reactor, the initial bed is generally for desulfurization and denitrogenation, and subsequent beds are for dearomatization.
Since the hydrogenation reaction is generally exothermic, interstage cooling, consisting of heat transfer devices between fixed bed reactors or between catalyst beds in the same reactor shell, can be employed. At least a portion of the heat generated from the hydrogenation process can often be profitably recovered for use in the hydrogenation process. Where this heat recovery option is not available, cooling may be performed through cooling utilities such as cooling water or air, or through use of a hydrogen quench stream injected directly into the reactors. Two-stage processes can provide reduced temperature exotherm per reactor shell and provide better hydrogenation reactor temperature control.
The reaction zone effluent is generally cooled and the effluent stream is directed to a separator device to remove the hydrogen. Some of the recovered hydrogen can be recycled back to the process while some of the hydrogen can be purged to external systems such as plant or refinery fuel. The hydrogen purge rate is often controlled to maintain a minimum hydrogen purity and remove hydrogen sulfide. Recycled hydrogen is generally compressed, supplemented with “make-up” hydrogen, and injected into the process for further hydrogenation.
Liquid effluent of the separator device can be processed in a stripper device where light hydrocarbons can be removed and directed to more appropriate hydrocarbon pools. Preferably the separator and/or stripper device includes means capable of providing effluents of at least one low-boiling liquid fraction and one high-boiling liquid fraction. Liquid effluent and/or one or more liquid fraction thereof is subsequently treated to incorporate oxygen into the liquid organic compounds therein and/or assist by oxidation removal of sulfur or nitrogen from the liquid products. Liquid products are then generally conveyed to blending facilities for production of finished distillate products.
Operating conditions to be used in the hydrogenation process include an average reaction zone temperature of from about 200° C. to about 450° C., preferably from about 250° C. to about 400° C., and most preferably from about 275° C. to about 350° C. for best results. Reaction temperatures below these ranges can result in less effective hydrogenation. Excessively high temperatures can cause the process to reach a thermodynamic aromatic reduction limit, hydrocracking, catalyst deactivation, and increase energy costs. Desulfurization, in accordance with the process of the present invention, can be less effected by reaction zone temperature than prior art processes, especially at feed sulfur levels below 500 ppm, such as in the second-stage dearomatization zone of a two-stage process.
The hydrogenation process typically operates at reaction zone pressures ranging from about 400 psig to about 2000 psig, more preferably from about 500 psig to about 1500 psig, and most preferably from about 600 psig to about 1200 psig for best results. Hydrogen circulation rates generally range from about 500 SCF/Bbl to about 20,000 SCF/Bbl, preferably from about 2,000 SCF/Bbl to about 15,000 SCF/Bbl, and most preferably from about 3,000 to about 13,000 SCF/Bbl for best results. Reaction pressures and hydrogen circulation rates below these ranges can result in higher catalyst deactivation rates resulting in less effective desulfurization, denitrogenation, and dearomatization. Excessively high reaction pressures increase energy and equipment costs and provide diminishing marginal benefits.
The hydrogenation process typically operates at a liquid hourly space velocity of from about 0.2 hr−1 to about 10.0 hr −1 , preferably from about 0.5 hr −1 to about 3.0 hr −1 , and most preferably from about 1.0 hr −1 to about 2.0 hr −1 for best results. Excessively high space velocities will result in reduced overall hydrogenation.
Useful catalyst for the hydrodesulfurization comprise a component capable to enhance the incorporation of hydrogen into a mixture of organic compounds to thereby form at least hydrogen sulfide, and a catalyst support component.
The catalyst support component typically comprises mordenite and a refractory inorganic oxide such as silica, alumina, or silica-alumina. The mordenite component is present in the support in an amount ranging from about 10 percent by weight to about 90 percent by weight, preferably from about 40 percent by weight to about 85 percent by weight, and most preferably from about 50 percent by weight to about 80 percent by weight for best results. The refractory inorganic oxide, suitable for use in the present invention, has a pore diameter ranging from about 50 to about 200 Angstroms and more preferably from about 80 to about 150 Angstroms for best results. Mordenite, as synthesized, is characterized by its silicon to aluminum ratio of about 5:1 and its crystal structure.
Further reduction of such heteroaromatic sulfides from a distillate petroleum fraction by hydrotreating would require that the stream be subjected to very severe catalytic hydrogenation order to convert these compounds into hydrocarbons and hydrogen sulfide (H 2 S), Typically, the larger any hydrocarbon moiety is, the more difficult it is to hydrogenate the sulfide. Therefore, the residual organo-sulfur compounds remaining after a hydrotreatment are the most tightly substituted sulfides.
Subsequent to desulfurization by catalytic hydrogenation, as disclosed herein further selective removal of sulfur or nitrogen from the desulfurized mixture of organic compounds can be accomplished by incorporation of oxygen into sulfur or nitrogen containing organic compounds thereby assisting in selective removal of sulfur or nitrogen from oxidation feedstocks.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In order to better communicate the present invention, still another preferred aspect of the invention is depicted schematically in FIG. 1 . Referring now to FIG. 1, organic feedstock comprising a liquid mixture of organic compounds derived from natural petroleum, the mixture having a gravity ranging from about 10° API to about 80° API is supplied through conduit 32 and into oxygenation reactor 110 containing a fixed, ebullient, or fluidized bed of heterogeneous oxygenation catalyst system for oxidation in the liquid phase with a gaseous source of dioxygen, such as air or nitrogen enriched air. In the embodiment illustrated in FIG. 1, the oxygenation reactor 110 contains an ebullating bed of heterogeneous catalyst, for example a particulate form of chromium molybdate or bismuth molybdate with or without magnesium.
Generally, oxygenation reactions are conducted at temperatures in a range of from about 25° C. to about 250° C., preferably at temperatures in a range of from about 65° C. to about 200° C., and more preferably at temperatures in a range of from about 100° C. to about 180° C. Suitable pressure for oxygenation reactions is pressure sufficient to maintain the organic feedstock in substantially a liquid state, typically pressure are in a range of from about 50 psi to about 600 psi.
Air or nitrogen enriched air is supplied to compressor 114 through supply conduit 116 , and the compressed gas is sparged into the bottom of oxygenation reactor 110 through conduit 118 . Heat generated by the exothermic oxidation reaction may cause a portion of the volatile organic compounds in the reaction medium to vaporize. Gaseous reactor effluent containing any such vaporized organic compounds, carbon oxides, nitrogen from the gas charged to the oxidation reaction and unreacted dioxygen pass through conduit 112 , effluent cooler 122 , and thereafter into overhead knock-out drum 120 through conduit 124 . Levels of dioxygen in the gaseous reactor effluent are low, preferably zero, but in some cases may be as high as 8 percent by volume.
Separated organic liquid from drum 120 is returned to oxygenation reactor 110 through conduit 126 . As needed aqueous liquid is discharged from drum 120 to blowdown disposal (not shown) through conduit 144 . Gas is vented from drum 120 , through conduit 128 , to a vent gas treatment unit (not shown) or flared. Beneficially, a portion of gases from drum 120 are supplied to compressor 114 for recycle to oxygenation reactor 110 .
Reactor effluent containing entrained particles of the heterogeneous oxygenation catalyst system in a mixture of gases and the liquid portion of the reaction mixture, is diverted from oxidation reactor 110 through conduit 132 and into centrifugal separator 130 . While a portion of the separated solids may be returned directly to oxidation reactor 110 , according to the embodiment illustrated in FIG. 1, separated solids concentrated in a liquid portion of the reaction mixture is supplied to catalyst recover/regeneration unit 138 from centrifugal separator 130 through conduit 136 .
Gases and liquid portions of the reaction mixture are transferred from centrifugal separator 130 into separation drum 140 . Gases separated by gravity from the other phase of the reaction mixture are transferred from separation drum 140 into the cooler overhead knock-out drum 120 through conduit 142 .
The separated organic liquid phase of the reaction mixture is supplied from settling drum 140 to liquid—liquid extractor 150 through conduit 152 . Preferably, the design of extractor 150 provides about 2 to about 5 theoretical stages of liquid—liquid extraction. Aqueous sodium bicarbonate solution, or other soluble chemical base capable to neutralize and/or remove acidic co-products of oxidation, is supplied to extractor 150 from source 156 through conduit 154 . Oxygenated product is transferred from extractor 150 to fuel blending facility 100 through conduit 92 .
In order to better communicate the present invention, still another preferred aspect of the invention is depicted schematically in FIG. 2 . Referring now to FIG. 2, a substantially liquid stream of middle distillates from a refinery source 12 is charged through conduit 14 into catalytic reactor 20 . A gaseous mixture containing dihydrogen (molecular hydrogen) is supplied to catalytic reactor 20 from storage or a refinery source 16 through conduit 18 . Catalytic reactor 20 contains one or more fixed bed of the same or different catalyst which have a hydrogenation-promoting action for desulfurization, denitrogenation, and dearomatization of middle distillates. The reactor maybe operated in upflow, downflow, or counter-current flow of the liquid and gases through the bed.
One or more beds of catalyst and subsequent distillation operate together as an integrated hydrotreating and fractionation system. This fractionation system separates unreacted dihydrogen, hydrogen sulfide and other non-condensable products of hydrogenation from the effluent stream and the resulting liquid mixture of condensable compounds is fractionated into a low-boiling fraction containing a minor amount of remaining sulfur and a high-boiling fraction containing a major amount of remaining sulfur.
Mixed effluents from catalytic reactor 20 are transferred into separation drum 24 through conduit 22 . Unreacted dihydrogen, hydrogen sulfide and other non-condensed compounds flow from separation drum 24 to hydrogen recovery (not shown) through conduit 28 . Advantageously, all or a portion of the unreacted hydrogen may be recycled to catalytic reactor 20 , provided at least a portion of the hydrogen sulfide has been separated therefrom.
Hydrogenated liquids flow from separation drum 24 into distillation column 30 through conduit 26 . Gases and condensable vapors from the top of column 30 are transferred through overhead cooler 40 , by means of conduits 34 and 42 , and into overhead drum 46 . Separated gases and non-condensed compounds flow from overhead drum 46 to disposal or further recovery (not shown) through conduit 49 . A portion of the condensed organic compounds suitable for reflux is returned from overhead drum 46 to column 30 through conduit 48 . Other portions of the condensate are beneficially recycled from overhead drum 46 to separation drum 24 and/or transferred to other refinery uses (not shown).
The low-boiling fraction having the minor amount of sulfur-containing organic compounds is withdrawn from near the top of column 30 . It should be apparent that this low-boiling fraction from the catalytic hydrogenation is a valuable product in itself. Beneficially, all or a portion of the low-boiling fraction in substantially liquid form is transferred through conduit 32 and into an oxygenation process unit 90 for catalytic oxidation in the liquid phase with a gaseous source of dioxygen, such as air or oxygen enriched air, for example as shown in FIG. 1. A stream containing oxygenated organic compounds is subsequently separated to recover, for example, a fuel or a blending component of fuel and transferred to fuel blending facility 100 through conduit 92 . The stream can alternatively be utilized as a source of feed stock for chemical manufacturing.
A portion of the high-boiling liquid at the bottom of column 30 is transferred to reboiler 36 through conduit 35 , and a stream of vapor from reboiler 36 is returned to distillation column 30 through conduit 35 .
From the bottom of column 30 another portion of the high-boiling liquid fraction having the major amount of the sulfur-containing organic compounds is supplied as oxidation feedstock to oxidation reactor 60 through conduit 38 .
An immiscible phase including at least peracetic acid and/or other organic peracids, is supplied to oxidation reactor 60 through manifold 50 . The liquid reaction mixture in oxidation reactor 60 is maintained substantially free of catalytic active metals and/or active metal-containing compounds and under conditions suitable for oxidation of one or more of the sulfur-containing and/or nitrogen-containing organic compounds. Suitably the oxidation reactor 60 is maintained at temperatures in a range of from about 80° C. to about 125° C., and at pressures in a range from about 15 psi to about 400 psi, preferably from about 15 psi to about 150 psi.
Liquid reaction mixture from reactor 60 is supplied to drum 64 through conduit 62 . At least a portion of the immiscible phase is separated by gravity from the other phase of the reaction mixture. While a portion of the immiscible phase may be returned directly to reactor 60 , according to the embodiment illustrated in FIG. 1 the phase is withdrawn from drum 64 through conduit 66 and transferred into separation unit 80 .
The immiscible phase contains water of reaction, carboxylic acids, and oxidized sulfur-containing and/or nitrogen-containing organic compounds which are now soluble in the immiscible phase. Acetic acid and excess water are separated from high-boiling sulfur-containing and/or nitrogen-containing organic compounds as by distillation. Recovered acetic acid is returned to oxidation reactor 60 through conduit 82 and manifold 50 . Hydrogen peroxide is supplied to manifold 50 from storage 52 through conduit 54 . As needed, makeup acetic acid solution is supplied to manifold 50 from storage 56 , or another source of aqueous acetic acid, through conduit 58 . Excess water is withdrawn from separation unit 80 and transferred through conduit 86 to disposal (not shown). At least a portion of the oxidized high-boiling sulfur-containing and/or nitrogen-containing organic compounds are transferred through conduit 84 and into catalytic reactor 20 .
The separated phase of the reaction mixture from drum 64 is supplied to vessel 70 through conduit 68 . Vessel 70 contains a bed of solid sorbent which exhibits the ability to retain acidic and/or other polar compounds, to obtain product containing less sulfur and/or less nitrogen than the feedstock to the oxidation. Product is transferred from vessel 70 to fuel blending facility 100 through conduit 72 . Preferably, in this embodiment a system of two or more reactors a system of two or more reactors containing solid sorbent, configured for parallel flow, is used to allow continuous operation while one bed of sorbent is regenerated or replaced.
Transportation fuels friendly to the environment are transferred from blending facility 100 through conduit 102 to storage and/or shipping (not shown).
In view of the features and advantages of processes in accordance with this invention using selected organic peracids in a liquid phase reaction mixture maintained substantially free of catalytic active metals and/or active metal-containing compounds to preferentially oxidize compounds in which a sulfur atom is sterically hindered rather than aromatic hydrocarbons, as compared to known desulfurization systems previously used, the following examples are given. The following examples are illustrative and are not meant to be limiting.
GENERAL
Oxygenation of a hydrocarbon product was determined by the difference between the high precision carbon and hydrogen analysis of the feed and product. Oxygenation , percent , = ( percent C + percent H ) analysis of feed - ( percent C + percent H ) analysis of oxygenated product
EXAMPLE 1
In this example a refinery distillate containing sulfur at a level of about 500 ppm was hydrotreated under conditions suitable to produce hydrodesulfurized distillate containing sulfur at a level of about 130 ppm, which was identified as hydrotreated distillate 150. Hydrotreated distillate 150 was cut by distillation into four fractions which were collected at temperatures according to the following schedule.
Fraction
Temperatures, ° C.
1
Below 260
2
260 to 288
3
288 to 316
4
Above 316
Analysis of hydrotreated distillate 150 over this range of distillation cut points is shown in Table I. In accordance with this invention a fraction collected below a temperature in the range from about 260° C. to about 300° C. splits hydrotreated distillate 150 into a sulfur-lean, monoaromatic-rich fraction and a sulfur-rich, monoaromatic-lean fraction.
TABLE I
ANALYSIS OF DISTILLATION FRACTIONS OF
HYDROTREATED DISTILLATE 150
Fraction Number
Item
1
2
3
4
Total
Weight, %
45
21
19
16
100
Sulfur, ppm
11.7
25
174
580
133
Mono-Ar, %
40.7
26.3
15.6
14.0
28.8
Di-Ar, %
0.4
5.0
5.4
5.6
3.1
Tri-Ar, %
0
0
0
0.8
0.1
Mono-Ar is mono-aromatics. Di-Ar is di-aromatics. Tri-Ar is tri-aromatics.
EXAMPLE 2
In this example a refinery distillate containing sulfur at a level of about 500 ppm was hydrotreated under conditions suitable to produce a hydrodesulfurized distillate containing sulfur at a level of about 15 ppm, which was identified as hydrotreated distillate 15.
Analysis of hydrotreated distillate 150 over the range of distillation cut points is shown in Table II. In accordance with this invention a fraction collected below a temperature in the range from about 260° C. to about 300° C. splits hydrotreated distillate 15 into a sulfur-lean, monoaromatic-rich fraction and a sulfur-rich, monoaromatic-lean fraction.
TABLE II
ANALYSIS OF DISTILLATION FRACTIONS OF
HYDROTREATED DISTILLATE 15
Fraction Number
Item
1
2
3
4
Total
Weight, %
53
16
20
11
100
Sulfur, ppm
1
2
13
80
12.3
Mono-Ar, %
35.8
20.9
14.8
12.0
5.6
Di-Ar, %
1.3
8.0
7.4
5.6
4.0
Tri-Ar, %
0
0
0
1.4
0.2
Mono-Ar is mono-aromatics. Di-Ar is di-aromatics. Tri-Ar is tri-aromatics.
EXAMPLE 3
This example describes a heterogeneous catalytic oxygenation according to the invention of a refinery distillate with a gaseous source of dioxygen. The distillate had a gravity of 20° API. Analysis of the distillate gave 233 ppm of sulfur, 4 ppm of nitrogen. A stirred autoclave, having a nominal volume of 1 liter, was charged with 299.5 g of distillate and 2.98 grams of a particulate oxygenation catalyst containing bismuth molybdate/iron promoted with magnesium. The oxygenation was carried out at a temperature of 160° C. and a pressure of 200 psig using gaseous oxygen diluted to 7 percent with nitrogen at a flow rate of 1200 sccm for 180 minutes. Analyses of the product determined a sulfur content of 12 ppm, a nitrogen content of 6 ppm, and a total acid number of 12.9 mg KOH/g. Oxygenation of the hydrocarbon portion of the product was 3.43 percent by weight.
EXAMPLE 4
This example describes heterogeneous catalytic oxygenation with a gaseous source of dioxygen according to the invention of another portion of the refinery distillate oxygenated in Example 3. The stirred autoclave was charged with 299.7 g of distillate and 3.01 grams of a particulate oxygenation catalyst containing 18 percent chromium as oxide and 1.5 percent platinum on γ-Al 2 O 3 (CrOPt/Al 2 O 3 ). This oxygenation was also carried out at a temperature of 160° C. and a pressure of 200 psig using gaseous oxygen diluted to 7 percent with nitrogen at a flow rate of 1200 sccm, but for 300 minutes. Analyses of the product determined a sulfur content of 13 ppm, a nitrogen content of 2 ppm, and a total acid number of 0.7 mg KOH/g. Oxygenation of a hydrocarbon product was 1.01 percent by weight.
EXAMPLE 5
This example describes a heterogeneous catalytic oxygenation according to the invention of a hydrotreated refinery distillate identified as S-25. This hydrotreated distillate had a gravity of 35° API. Analysis of the distillate gave 20 ppm of sulfur, 18 ppm of nitrogen. The stirred autoclave was charged with 185.8 g of distillate and 1.84 grams of a particulate oxygenation catalyst containing bismuth molybdate/iron promoted with magnesium. The oxygenation was carried out at a temperature of 160° C. and a pressure of 200 psig using gaseous oxygen diluted to 7 percent with nitrogen at a flow rate of 1200 sccm for 300 minutes. Analyses of the product determined a sulfur content of 12 ppm, a nitrogen content of 7 ppm, and a total acid number of 2.37 mg KOH/g. Oxygenation of the hydrocarbon portion of the product was 1.48 percent by weight.
EXAMPLE 6
This example describes heterogeneous catalytic oxygenation with a gaseous source of dioxygen of another portion of the hydrotreated distillate oxygenated in Example 5. The stirred autoclave was charged with 299.3 g of distillate and 3 grams of a particulate oxygenation catalyst containing 18 percent chromium as oxide and 1.5 percent platinum on γ-Al 2 O 3 (CrOPt/Al 2 O 3 ). The oxygenation was also carried out at a temperature of 160° C. and a pressure of 200 psig using gaseous oxygen diluted to 7 percent with nitrogen at a flow rate of 1200 sccm, but for 245 minutes. Analyses of the product determined a sulfur content of 9 ppm, a nitrogen content of 8 ppm, and a total acid number of 2.89 mg KOH/g. Oxygenation of a hydrocarbon product was 1.01 percent by weight.
EXAMPLE 7
This example describes heterogeneous catalytic oxygenation with a gaseous source of dioxygen of another portion of the hydrotreated distillate oxygenated in Example 5. The stirred autoclave was charged with 299.4 g of distillate and 3 grams of a particulate oxygenation catalyst containing 0.5 percent Na 2 Cr 2 O 7 on γ-Al 2 O 3 . The oxygenation was also carried out at a temperature of 160° C. and a pressure of 200 psig using gaseous oxygen diluted to 7 percent with nitrogen at a flow rate of 1200 sccm. Analyses of the product determined a sulfur content of 6 ppm, a nitrogen content of 9 ppm, and a total acid number of 7.77 mg KOH/g. Oxygenation of a hydrocarbon product was 2.45 percent by weight.
EXAMPLES 8-11
Hydrotreated refinery distillate S-25 was partitioned by distillation to provide feedstock for oxidation using hydrogen peroxide and acetic acid. The fraction collected below temperatures of about 300° C. was a sulfur-lean, monoaromatic-rich fraction identified as S-25-B300. Analyses of S-25-B300 determined a sulfur content of 3 ppm, a nitrogen content of 2 ppm, and 36.2 percent mono-aromatics, 1.8 percent di-aromatics, for a total aromatics of 37.9 percent. The fraction collected above temperatures of about 300° C. was a sulfur-rich, monoaromatic-poor fraction identified as S-25-A300. Analyses of S-25-A300 determined a sulfur content of 35 ppm, a nitrogen content of 31 ppm, and aromatic content was 15.7 percent mono-aromatics, 5.8 percent di-aromatics, and 1.4 percent tri-aromatics, for a total aromatics of 22.9 percent.
Into a 250 mL, three-neck round bottom flask equipped with a reflux condenser, a mechanical agitator, a nitrogen inlet and outlet, were charged 100 g of S-25-A300. The reactor was also charged with varying amounts of glacial acetic acid, distilled and deionized water, and 30 percent aqueous hydrogen peroxide. The mixture is heated with stirring and under a slight flow of nitrogen at approximately 93° C. to 99° C. for approximately two hours. At the end of the reaction period, the agitation ceased and the contents of the flask rapidly formed into two liquid layers. A sample of the top layer (organic) was withdrawn and dehydrated with anhydrous sodium sulfate. Contents of the flask was stirred and permitted to cool to ambient temperature before approximately 0.1 g of manganese dioxide is added to decompose any residual hydrogen peroxide. At this point, the mixture was stirred for an additional 10 minutes before the entire reactor content was collected.
Table III gives variables and analytical data which demonstrate that increasing concentration of acetic acid increases concentration of total sulfur in the aqueous layer. Increasing level of acetic acid caused sulfur in the organic layer to decrease by 35 ppm. These data clearly indicate that an essential element of the present of invention is the use of organic peracids where the carbonyl carbon is attached to hydrogen or a hydrocarbon radical. In general such hydrocarbon radical contains from 1 to about 12 carbon atoms, preferably from about 1 to about 8 carbon atoms. Acetic acid was shown to extract oxidized sulfur compounds from the organic phase and into the aqueous phase. Without acetic acid, no noticeable sulfur transfer into the aqueous phase was observed.
TABLE III
EXPERIMENTAL PARAMETERS AND ANALYTICAL RESULTS
FOR OXIDATIONS OF LS-25-A300
EXAMPLE
8
9
10
11
H 2 O 2 , mL
34
34
34
34
HOAc, mL
0
25
50
75
H 2 O, mL
100
75
50
25
Sulfur Aq, ppm
<2
<2
13
14
Sulfur Org, ppm
33
30
21
18
H 2 O 2 is 30 percent hydrogen peroxide. HOAc is glacial acetic acid.
H 2 O is distilled water.
EXAMPLE 12
Hydrotreated refinery distillate S-25 was partitioned by distillation to provide feedstock for oxidation using an immiscible aqueous solution phase containing hydrogen peroxide and acetic acid. The fraction of S-25 collected above temperatures of about 316° C. was a sulfur-rich, monoaromatic-poor fraction identified as S-25-A316. Analyses of S-25-A316 determined a sulfur content of 80 ppm, and a nitrogen content of 102 ppm.
A 250 mL, three-neck round bottom flask equipped with a reflux condenser, a magnetic stir bar or mechanical agitator, a nitrogen inlet and outlet, was charged with 100 g of the S-98-25-A-316, 75 mL glacial acetic acid, 25 mL water, and 17 mL (30%) hydrogen peroxide. The mixture was heated to 100° C. and stirred vigorously under a very slight flow of house nitrogen for two hours.
At the end of the reaction period, analysis of the top layer (organic) found total sulfur and nitrogen of 54 ppm sulfur and 5 ppm nitrogen. Contents of the flask was again stirred and cooled to room temperature. At room temperature, approximately 0.1 g of manganese dioxide (MnO 2 ) was added to decompose any excess hydrogen peroxide and stirring continued for 10 minutes. The entire contents of the flask were then poured into a bottle with a vented cap. Analysis of the bottom layer (aqueous) found 44 ppm of total sulfur.
EXAMPLE 12a
A second oxidation of hydrotreated refinery distillate S-25-A316 was conducted as described in Example 12 by charging 100 mL glacial acetic acid, but no water. The organic layer was found to contain 27 ppm sulfur and 3 ppm nitrogen. The aqueous layer contained 81 ppm sulfur.
EXAMPLE 12b
The entire contents of the flask from both Example 12 and Example 12a were combined. A bottom layer was then removed, leaving behind a combined organic layer from both experiments. The organic layer was dried over anhydrous sodium sulfate to remove any residual water from the process. After the spent sodium sulfate was removed via vacuum filtration, the filtrate was percolated through enough alumina so that the filtrate to alumina ratio ranged from 7:1 to 10:1. Analysis of organic layer emerging from the alumina was 32 ppm of total sulfur and 5 ppm of total nitrogen.
EXAMPLE 13
A hydrotreated refinery distillate identified as S-150 was partitioned by distillation to provide feedstock for oxidations using peracid formed with hydrogen peroxide and acetic acid. Analyses of S-150 determined a sulfur content of 113 ppm, and a nitrogen content of 36 ppm. The fraction of S-98 collected above temperatures of about 316° C. was a sulfur-rich, monoaromatic-poor fraction identified as S-150-A316. Analyses of S-150-A316 determined a sulfur content of 580 ppm and a nitrogen content of 147 ppm.
A 3 liter, three neck, round bottom flask equipped with a water-jacketed reflux condenser, a mechanical stirrer, a nitrogen inlet and outlet, and a heating mantel controlled through a Variac auto-transformer, was charged with 1 kg of S-150-A316, 1 liter of glacial acetic acid and 170 mL of 30 percent hydrogen peroxide.
A slight flow of nitrogen was initiated and this gas then slowly swept over the surface of the reactor content. The agitator was started to provide efficient mixing and the contents were heated. Once the temperature reaches 93° C., the contents were held at this temperature for reaction time of 120 minutes.
After the reaction time had elapsed, the contents continued to be stirred while the heating mantel turned off and removed. At approximately 77° C., the agitator was stopped momentarily while approximately 1 g of manganese dioxide (MnO 02 ) was added through one of the necks of the round bottom flask to the biphasic mixture to decompose any unreacted hydrogen peroxide. Mixing of the contents with the agitator was then resumed until the temperature of the mixture was cooled to approximately 49° C. The agitation was ceased to allow both organic (top) and aqueous (bottom) layers to separate, which occurred immediately.
The bottom layer was removed and retained for further analysis in a lightly capped bottle to permit the possible evolution of oxygen from any undecomposed hydrogen peroxide. Analysis of the bottom layer was 252 ppm of sulfur.
The reactor was cautiously charged with 500 mL of saturated aqueous sodium bicarbonate to neutralize the organic layer. After the bicarbonate solution was added, the mixture was stirred rapidly for ten minutes to neutralize any remaining acetic acid. The organic material was dried over anhydrous 3A molecular sieve. Analysis of the dry organic layer, identified as PS-150-A316, was 143 ppm of sulfur, 4 ppm of nitrogen, and a total acid number of 0.1 mg KOH/g.
EXAMPLE 14
A 500 mL separatory funnel was charged with 150 mL of PS-150-A316 and 150 mL of methanol. The funnel was shaken and then the mixture was allowed to separate. The bottom methanol layer was collected and saved for analytical testing. A 50 mL portion of the product was then collected for analytical testing and identified as sample ME14-1.
A 100 mL portion of fresh methanol was added to the funnel containing the remaining 100 mL of product. The funnel was again shaken and the mixture was allowed to separate. The bottom methanol layer was collected and saved for Analytical testing. A 50 mL portion of the methanol extracted product was collected for analytical testing and identified as sample ME14-2.
Into the remaining 50 mL of product in the funnel, 50 mL of fresh methanol was added. The funnel was again shaken and the two layers were allowed to separate. The bottom methanol layer was collected and saved for analytical testing. 50 mL of the product is collected for analytical testing and identified as sample ME14-3.
The Analytical results obtained for this example are shown in Table IV.
TABLE IV
REDUCTION OF SULFUR & TOTAL ACID NUMBER
BY METHANOL EXTRACTIONS
TAN,
Sulfur,
Sample
mg KOH/g
ppmw
PS-150-A316
0.11
143
ME14-1
0.02
35
ME14-2
0.02
14
ME14-3
0.02
7
These results clearly show that methanol was capable of selectively removing oxidized sulfur compounds. Additionally, acidic impurities were also removed by methanol extraction.
EXAMPLE 15
A separatory funnel was charged with 50 mL of PS-150-A316 and 50 mL water. The funnel was shaken and the layers were allowed to separate. The bottom water layer was collected and saved for analytical testing. The hydrocarbon layer was collected for analytical testing and identified as E15-1W. Table V presents these results.
TABLE V
REDUCTION OF SULFUR BY WATER EXTRACTION
TAN
Nitrogen
Sulfur
Sample
mg KOH/g
ppmw
ppmw
PS-150-A316
0.11
4
143
E15-1W
—
5
100
The water extraction results show that water was useful in removing oxidized sulfur compounds from the distillate.
EXAMPLE 16
Five hundred grams of PS-150-A316 were percolated through 50 grams of anhydrous acidic alumina. The collected product was identified as E16-1A and analyzed. The data are presented in Table VI.
TABLE VI
REDUCTION OF SULFUR AND NITROGEN BY ALUMINA
TREATMENT
Nitrogen
Sulfur
Sample
ppmw
ppmw
PS-150-A316
4
143
E16-1A
2
32
These data demonstrate that alumina treatment was also effective in the removal of oxidized sulfur and nitrogen compounds from the distillate.
Analysis was conducted on alumina treated material E16-1A and compared with the PS-150-A316. The analysis showed an absence of any dibenzothiophene in the products, while the feed contained about 3,000 ppm of this impurity.
EXAMPLE 17
Hydrotreated refinery distillate S-25 was partitioned by distillation to provide a feedstock for oxidations using peracid formed with hydrogen peroxide and acetic acid. The fraction of S-25 collected below temperatures of about 288° C. was a sulfur-lean, monoaromatic-rich fraction identified as S-DF-B288. The fraction of S-25 collected above temperatures of about 288° C. was a sulfur-rich, monoaromatic-poor fraction identified as S-DF-A288. Analyses of S-DF-A288 determined a sulfur content of 30 ppm.
A series of oxidation runs were conducted as described in Example 13 and the products combined to provide amounts of material needed for cetane rating and chemical analysis. A flask equipped as in Example 13 was charged with 1 kg of S-DF-A288, 1 liter of glacial acetic acid, 85 mL of deionized and distilled water and 85 mL of 30 percent hydrogen peroxide.
In one procedure a batch of dried oxidized distillate was percolated through a second column packed with 250 mL of dried, acidic alumina (150 mesh). The distillate to alumina ratio was about 4:1 (v/v). The alumina was used for approximately 4 batches of 1,000 mL, and replaced.
In another procedure approximately 100 grams of alumina was placed in a 600 mL Buchner funnel equipped with a fritted disc (fine). Dried distillate was poured over the alumina and more quickly treated as the vacuum draws the distillate through the alumina in a shorter time.
Every batch of post-alumina treated material was submitted for total sulfur analysis to quantify the sulfur removal efficiency from the feed. All alumina treated materials had a sulfur concentration of less than 3 ppmw, and in general about 1 ppmw sulfur. A blend of 32 batches of alumina treated material was identified as BA-DF-A288.
For the purposes of the present invention, “predominantly” is defined as more than about fifty percent. “Substantially” is defined as occurring with sufficient frequency or being present in such proportions as to measurably affect macroscopic properties of an associated compound or system. Where the frequency or proportion for such impact is not clear, substantially is to be regarded as about twenty per cent or more. The term “essentially” is defined as absolutely except that small variations which have no more than a negligible effect on macroscopic qualities and final outcome are permitted, typically up to about one percent.
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Economical processes are disclosed for production of components for refinery blending of transportation fuels which are liquid at ambient conditions by selective oxygenation of refinery feedstocks comprising a mixture of organic compounds. The organic compounds are oxygenated in a liquid reaction medium with an oxidizing agent and heterogeneous oxygenation catalyst system which exhibits a capability to enhance the incorporation of oxygen into a mixture of liquid organic compounds to form a mixture comprising hydrocarbons, oxygenated organic compounds, water of reaction, and acidic co-products. The mixture is separated to recover at least a first organic liquid of low density and at least a portions of the catalyst metal, water of reaction and acidic co-products. Advantageously, the organic liquid is washed with an aqueous solution of sodium bicarbonate solution, or other soluble chemical base capable to neutralize and/or remove acidic co-products of oxidation, and recover oxygenated product.
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BACKGROUND AND SUMMARY OF THE INVENTION
As the number of oil and gas wells completed in sensitive environments has increased so has the need to provide a dependable shutoff valve, for use in subsurface well tubing and in other critical locations, and to provide for adequate testing of such a valve, to make more certain that it will close when required to do so in an emergency.
The present invention is directed to a subsurface shutoff valve in the form of a sleeve and control means, which is summarized in the following objects:
First, to provide a sleeve type of shutoff valve the sleeve of which provides, when open, an unobstructed flow passage of maximum internal diameter for a given external sleeve diameter and is surrounded by a peripheral control chamber which, when pressurized, causes the valve to effect a full seal;
Second, to provide a sleeve type shutoff valve the sleeve of which is formed of readily deformable elastomeric material and is provided with novel reinforcing so arranged that, when subjected to external pressure to close the valve, the reinforcing limits axial displacement of the elastomeric material even when the valve is subjected to an extreme pressure differential between its ends.
Third, to provide a shutoff valve, as indicated in the preceding objects, and control means therefore embodying a pressure-fluid reservoir as well as novelly arranged control valves connected to the surface through control and vent lines.
Fourth, to provide a shutoff valve and control means, as indicated in the preceding objects, in which the control means causes the shutoff valve to close automatically in the event of either surface damage at the wellhead that ruptures the control line or the development of a leak in the control line.
Fifth, to provide a shutoff valve and control means, as indicated in the other objects, whereby at regular intervals or at any other time the high-pressure reservoir can be checked for adequate pressure and if necessary replenished from a reserve surface supply of high-pressure fluid.
Sixth, to provide a shutoff valve and control means whereby the shutoff valve may be operated manually from the surface.
DESCRIPTION OF THE FIGURES
FIG. 1 is an essentially diagrammatical view of a tubing string provided with the subsurface shutoff valve and control means, illustrating the relative position of the major components.
FIG. 2 is a similar view of the tubing string, showing diagrammatically the internal mechanism provided in the control valve housing, and also indicating diagrammatically the surface equipment utilized in the control means.
FIG. 3 is a fragmentary longitudinal sectional view of the shutoff valve shown in its open position.
FIG. 4 is a transverse view taken at section 4--4 of FIG. 3.
FIG. 5 is a fragmentary transverse view taken at section 5--5 of FIG. 3, with the end-loops in the prestressed longitudinal reinforcing cord exposed.
FIG. 6 is an enlarged fragmentary transverse view taken at section 6--6 of FIG. 4.
FIG. 7 is a fragmentary longitudinal sectional view corresponding to FIG. 3 but showing the valve in the closed, or shutoff, condition.
FIG. 8 is an enlarged fragmentary transverse view taken at section 8--8 of FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference is first directed to FIGS. 3 through 8 which show the shutoff valve designated generally by 1. The shutoff valve includes a housing 2 which is cylindrical and is provided with a small pressure fluid supply duct 3 extending axially along the housing. The supply duct is provided with an entrance end 4 at the upper end of the housing and an inlet port directed into the housing at its midportion.
The ends of the housing 2 receive end collars 6 which are joined and sealed to the housing by means of welds 7. The end collars are provided with internal screw threads 8 so that the shutoff valve may be interposed in a tubing string 9.
Continuing from each collar 6 is a short tubular stem 10 spaced from the inner wall of the housing. Adjacent the corresponding collar 6 each tubular stem is provided with an outwardly directed peripheral channel 11. Adjacent the channel 11 each tubular stem is provided with a peripheral set of radially projecting rib elements or prongs 12 which are divided into pairs by the outwardly directed peripheral channel 11. The middlemost extremity of each tubular stem 10 terminates in a lip 60, which is rounded to a maximal radius for the purpose of minimizing bending stresses in the closed sleeve and its reinforcing, particularly in the pre-stressed longitudinal reinforcing cord 14.
The reinforcing cord 14 is strung longitudinally between the two sets of projecting rib-elements 12. It is pre-stressed, i.e., optimally tensioned during installation, and is folded over the axial extremities of the two sets of projecting rib-elements, forming the U-shaped end-loops 15. The two extremities of the pre-stressed reinforcing cord 14 are joined together near the midportion of the sleeve by suitable means, not shown. When looped over the projecting rib-elements 12, the reinforcing cord 14 forms a plurality of parallel longitudinally extending pre-stressed reinforcing elements. Wrapped about these pre-stressed longitudinal elements is a helical reinforcing cord 17 and wrapped about this helical reinforcing 17 are several convolutions of reinforcing fabric 18. This fabric extends at each end to cover the pre-stressed longitudinal reinforcing elements where they cross the channel 11. The fabric is bound within the channel 11 by being tightly wrapped with the circumferential retainer cord 16. The cords 14, 16, and 17 and the fabric 18 are formed of high strength plastic material or maybe fiberglass or maybe steel strands or a mixture of steel strands with the plastic or glass fiber strands.
The cords 14, 16 and 17 and the fabric 18 are molded within a tubular sleeve 19 formed of rubber or other elastomeric material. This sleeve has approximately the same internal diameter as that of the tubular stems 10, and forms a substantial inner lamination 20 extending between the stems 10. The sleeve also includes an outer lamination 21 encompassing the reinforcing. Also, the sleeve includes end portions 22 which extend over the tubular stems 10 and into the channels 11 and 13, and completely surround the ribs 12. The exterior of the sleeve 19 forms with the interior of the housing 2 an annular control-chamber 23.
The housing 2 withstands the various stresses arising from its being interposed in and part of the tubing string 9, and in addition withstands the pressure exerted by the pressure fluid in the annular control-chamber 23 and the axial compression exerted through the end collars 6 by the plurality of pre-stressed longitudinal elements that comprise the reinforcing cord 14.
Operation of the shutoff valve is as follows:
The inside diameter of the sleeve 19 is essentially the same as the internal diameter of the tubing string 9 in which the shutoff valve is founded. Thus under normal flow conditions the sleeve functions merely as a length of tubing, without increased flow resistance. The distance between the tubular stems 10 is on the order of one foot or more. By reason of the reinforcing a substantial excess of external pressure over internal pressure is required to compress the sleeve radially inward. When pressure fluid at such required excess pressure is applied through the duct 3, the inner lamination 20 contracts and folds upon itself as indicated in FIG. 8 until the midportion of the sleeve forms a closed cylinder. As the external pressure increases, the typical cross-section of the pre-stressed longitudinal reinforcing cord 14 compresses circumferentially and expands radially, as indicated in FIG. 8, and the helical reinforcing as well as the fabric reinforcing tend to assume a corrugated form. Adjacent to each tubular stem 10 in the closed sleeve there is formed a diameter-transition zone 24, along which the axial aperture varies from fully closed to fully open and in which the longitudinal reinforcing 14 is formed into a bell shape with an arched profile. This curvature permits the reinforcing in this zone to both support the sleeve 19 against the collapsing effect of the excess of external over internal pressure and anchor the sleeve against any substantial axial displacement, even though the pressure differential between the two ends of the sleeve may be extremely high.
Reference is now made to FIGS. 1 and 2, in which the shutoff valve 1 is shown interposed in the tubing string 9. Interposed in the tubing string above the shutoff valve is an annular housing 25 for the control valves, which is joined by a connecting line 29 to the pressure fluid supply 31. Interposed in the tubing string 9 below the shutoff valve is an annular subsurface pressure-reservoir 27 joined by a connecting line 28 to the control-valve housing 25. Extending upwardly from the control-valve housing 25 to the surface of the well is a control line 29 and a vent line 30. At the surface the control line is connected to a pressure tank 31 through a valve 32 and is also connected to the pressure tank through a bypass line having a regulator 33 and isolation valves 34. The control line 29 is also provided with a bleed valve 35. To facilitate the control and operation of the subsurface equipment both the control line 29 and the vent line 30 are provided at the the surface with indicating flow meters 58, of the rotameter or orifice-meter type. The vent line 30 is also provided with an emergency closure valve 59, which is normally sealed and locked in the open position.
Within the control-valve housing are four control valves, comprising an emergency valve 36, an overriding delivery valve 37, a low-pressure vent-valve 38, and a high-pressure vent-valve 39. As the volume of pressure fluid that must pass through the duct 3 in order to close the shutoff valve is relatively small, the various pressure fluid lines may be of small diameter and the four control valves 36, 37, 38 and 39 may also be of small diameter, so that they may be fitted into the annular housing 25, spaced equally around its central passage-way for the tubing string 9.
The valves contained in the control valve housing may be similar in most respects. Each valve includes a charging chamber 40 separated by an upper bulkhead 41 from a bellows chamber 42 containing a bellows 43 which is joined to the upper bulkhead 41. Each bellows chamber 42 is separated by a middle bulkhead 44 from an upper flow-chamber 45 which in turn is separated by a lower bulkhead 46 from a lower flow-chamber 47.
The bellows 43 in each control valve contains an upper valve element 48 which moves upwardly to close the port in the upper bulkhead 41. Each control valve is also provided with a lower valve-element 49. In control valves 36 and 39 this element 49 is located in the lower flow-chamber 47, so that upward movement of the element will close the port in the lower bulkhead 46. In control valves 37 and 38, however, the lower valve element 49 is located in the upper flow-chamber 45 and moves downward to close the port in the lower bulkhead 46. In all four control valves the upper and lower valve elements 48 and 49 are joined by a valve stem 50. Each of these valve stems is provided with a spring 51 which in control valves 36, 38 and 39 extends between the middle bulkhead 44 and the bellows 43, whereas in control valve 37 the spring extends between the middle bulkhead 44 and the lower valve element 49. In every case the valve stem 50 is sealed where it penetrates the bellows 43. The middle bulkhead 44 in control valves 36, 38 and 39 is provided with a packing gland 52 to seal the valve stem 50, but this seal is not necessary in control valve 37.
Branch lines 53 extend from the control line 29 to each of the bellows chambers 42. In control valve 37 this line also connects to the upper flow chamber 45. There is also a branch line 54 from the control line 29 to the connecting line 28, which extends to the reservoir 27. The branch line 54 is connected to the flow chamber 45 in control valve 36, and includes the check valve 55 to prevent backflow from the reservoir 27 to the control line 29. A cross line 56 connects the chambers 47 of valves 36, 37 and 38. The cross line 56 is joined to connecting line 26 leading to the pressure fluid supply duct 3. Another cross-line 57 extends between flow chamber 45 of valve 38 and flow chamber 47 of valve 39.
The surface pressure-tank 31 is maintained at a pressure above that required to close the shutoff valve 1. This tank pressure must substantially exceed the pressure in the well tubing at the shutoff valve 1. High pressure fluid is delivered from the tank 31 through line 29, branch line 54 through check valve 55 to line 28 and the reservoir 27. In all of the control valves the bellows 43 and the lower portion of the charging chamber 40 are filled with an inert liquid. The upper portion of the charging chamber is filled with inert gas to an accurately measured charging pressure. In control valves 36, 38 and 39 the charging pressure is below the constant maintenance pressure that is normally sustained by the pressure regulator 33, or may be essentially equal to such maintenance pressure due to the presence of the springs 51. In control valve 37 the charging pressure is commensurate with that in the reservoir 27.
The control line 29 and the chambers 42 surrounding the bellows 43 are normally pressurized at the maintenance pressure, for example 300 pounds per square inch, this being sufficient to hold the upper and lower valve elements 48 and 49 of valve 36 in a closed position and to hold valve element 48 in valve 38 in a closed position. Valve 38, however, is constructed so that in this condition of valve element 48 the valve element 49 is in an open position. The chamber 40 of valve 39 is pressurized to a point above the maintenance pressure, so that the pressure in its chamber 40 is sufficient to hold both of its valve elements 48 and 49 in open position.
The maintenance pressure that is normally present in the control line 29 is sufficient to hold valve element 49 of valve 36 in its closed position, as the effective area of the valve element 49 is substantially less than the effective area of the corresponding bellows 43. Under these conditions there is no release of pressure fluid from the reservoir 27. Should the pressure in the control line 29 be substantially reduced below the maintenance pressure, either deliberately or by an accident, such as damage to the upper region of the tubing string to which the line 29 is attached, the resulting reduction in the seating force exerted upward by the control-line pressure on the bellows 43 will cause the opening forces exerted downward by the charging pressure against the bellows and by the reservoir pressure against the valve element 49, to predominate and thereby open the valve element 49, thus connecting the reservoir 27 to the shutoff valve 1. The drop in pressure in the control line 29 causes the valve element 49 of valve 38 to close and prevent the escape of pressure fluid through the vent line 30. Meanwhile the valve element 49 of valve 39 remains open, but with no effect, since valve 38 is closed. The pressure fluid reaching the control chamber of the shutoff valve 1 closes it by acting upon the tubular valve body 19.
Whenever the maintenance pressure is subsequently restored control valve 36 closes off the flow of pressure fluid from the reservoir 27, the pressure fluid trapped in the shutoff valve is vented by the opening of valve 38, and the shutoff valve 1 then opens.
Should it be desired to operate the shutoff valve 1 directly without use of the pressure fluid from the reservoir 27, the control line 29 is connected directly to the pressure tank 31 which provides sufficient pressure to cause valve element 49 of valve 37 to open connecting the control line 29 directly to the line 26 and the supply duct 3 of the shutoff valve. Such high pressure closes valve element 49 of valve 39 so that the high pressure may be maintained. When it is desired to reopen the valve 1, the bleed valve 35 is opened permitting the control-line pressure to drop to the maintenance pressure, at which pressure valve 39 opens first, followed by valve 1.
Although the shutoff valve 1 is intended primarily for full-bore shutoff it may also be used for annular shutoff, in case the bore of the shutoff valve is occupied when it is closed by some such object as a rod, wire, cable, or tube.
Having fully described my invention it is to be understood that I am not to be limited to the details herein set forth, but that my invention is of the full scope of the appended claims.
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A shutoff valve and control means particularly adapted for subsurface use in oil or gas wells, the shutoff valve being in the form of a sleeve having both circumferential and pre-stressed-longitudinal reinforcing, so arranged as to permit radial contraction of the sleeve under external closing pressure until passage therethrough is completely closed, while preventing rupture of the sleeve from pressure differential, between either its ends or its exterior and interior; the shutoff valve, being controlled by a set of four control valves and a pressure-fluid reservoir, both adjacent to the shutoff valve, is connected to the surface by a control line and a vent line; the set of control valves comprising an emergency-delivery valve, a overriding-delivery valve, a low-pressure vent-valve, and a high-pressure vent-valve.
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TECHNICAL FIELD
This invention relates to methods and apparatus for cutting elastomeric materials at low skive angles, in particular cutting layered composites of elastomeric materials including layers containing reinforcing materials.
BACKGROUND OF THE INVENTION
Various methods and apparatus have been used for the cutting of sheets of elastomeric material. Such elastomeric material might consist of single sheets of the homogeneous material, or multiple layered sheets of materials having properties that are different from one another. In the case of multiple layered sheets of elastomeric material that, for various reasons, need to be cut, one or more of the layers might contain reinforcing cords or fibers made of metal or fabric. Such reinforcing cords or fibers might be simply aligned in such a way as to be parallel to one another. Furthermore, the elastomeric materials that are to be cut may or may not be cured or vulcanized at the time of cutting.
Prior art cutting methods and apparatus include cutting wheels, ultrasonic cutters, guillotine knives, wire cutters and vibrating scroll cutters whose active cutting principle is a saw blade or a blade or a tensioned wire.
While such prior art cutting methods are effective to varying degrees, each has disadvantages. For example, the guillotine knife is somewhat effective in cutting composite elastomeric materials, but it has the disadvantage of having a tendency to deform the cut surfaces of the elastomeric material as the knife penetrates the material. Such deformation of the cut edge increases the difficulty of subsequent splicing the ends of the elastomeric material. Moreover, the guillotine knife produces a continually degraded cut surface as the blade becomes dull and as small pieces of elastomer began to build up on the blade. Yet another disadvantage was the inability of the blade to cut at an angle less than 30 degrees relative to the plane of the material being cut. The guillotine blade also tends to generate heat during the cutting process such that, as numerous cuts are made, the temperature of the knife becomes sufficiently elevated in some cases to induce precuring of unvulcanized elastomer in the region of the cut, which then inhibits subsequent proper splicing along the cut edges.
Another prior art cutting system and method, disclosed in U.S. Pat. No. 5,638,732, employs a cutting wire. This system could not, however, be used to cut preassembled elastomeric composite sheets containing reinforcing cords because the reinforcing cords themselves, though aligned more or less parallel to the direction of the cut, get severed. This deficiency is actually inherent to nearly every prior art cutting technology including ultrasonic knives, that cut composite elastomeric preassemblies at relatively low skive angles. That is to say, nearly all prior art cutting methods tended to cut the parallel-aligned cords that are used to reinforce one or more layers of reinforced ply. The cut is ideally intended to be made between the parallel-aligned reinforcing cords. One prior art exception is the scroll cutter, which can cut at low skive angles without also risking cutting the reinforcing cords.
The scroll cutter cannot, however, initiate its cut at a low skive angle through a cord reinforced sheet of preassembled composite elastomeric sheets, because of its geometry, which includes a wire held at each end by a fixture. The scroll cutter must start its cut from the side of the preassembly, such that the cutting has difficulty entering the ply without splitting the reinforcing cords. Even at a 90-degree skive angle, the reliability of not splitting cords is in question. At low skive angles it becomes exponentially difficult to enter the ply without splitting a ply cord. Sometimes the reinforced ply end will be buried under the other layers, such as, in the case of tire manufacturing, the sidewall layer or other layers such as the extreme edge of the preassembly within the context of envelope construction. This adds another dimension of difficulty for the wire scroll cutter to cut reliably a preassembly with reinforced layers, such as specifically, the ply of tires.
Ultrasonic cutting systems as disclosed in U.S. Pat. No. 5,265,508, can cut stock material at low skive angles. However, they require that the material be secured to an anvil during cutting. Another system, disclosed in U.S. Pat. No. 4,922,774, employs an ultrasonic cutting device, which vibrates a knife that moves across an elastomeric strip. However, this system is limited to cutting angles of between 10 and 90 degrees, and it does not provide for cutting between parallel disposed, reinforcement cords within the strip, which is to say, the cords can get cut.
Various method have been attempted to cut through cord-reinforced composites employing ultrasonic knives. In PCT publication No. WO 00/23261, a pair of ultra sonic blades are employed wherein after the article to be cut is pierced in a central region the two blades cut in opposite directions toward each lateral edge of the composite.
In PCT publication No WD 00151810 an ultrasonic skive cuts above the cord reinforced member as a cutting knife follows making a second cut through the ply and between parallel cords thus forming an abutment surface for subsequent tire splicing of the cut to length segment. Each of these concepts requires multiple cutting mechanisms and are arguable complex to build and maintain the equipment.
A significant problem with the prior art cutting systems and methods is the inability to cut at angles less than 30 degrees relative to the plane of the elastomeric layers being cut without deformation or precuring the material. This can be a problem in, for example, automated tire building operations wherein the cutting has to be done precisely and quickly and where the cutter can also provide improvements to the cut surface which is subsequently to be spliced.
An ideal cutting method and apparatus should be able to make cuts at low angles relative to the plane of the elastomeric sheet being cut, and it should be able to do so without cutting the parallel-aligned reinforcing cords between which the cutter is ideally to move. It should also be able to make these low angle cuts rapidly and reliably.
SUMMARY OF THE INVENTION
A method of cutting segments to desired lengths from the strip of elastomeric material as disclosed. The segments have a width W, elastomeric strips being formed of a plurality of tire components, at least one of the tire components being a cord reinforced component. The cords of the reinforced tire component are substantially parallel oriented in the direction of a cutting path formed across the width W.
The method has the step of moving an ultrasonic knife into cutting engagement of the elastomeric strip while supporting the strip along the cutting path. Cutting the segment at a skive angle α. Impacting a cord of the cord reinforced component while cutting thereby lifting said cord over the ultrasonic knife as the segment is being cut. The impacted cord is at a cut end adjacent to the cutting path. The method further has the step of orienting a cutting edge on the ultrasonic knife inclined at an acute angle θ relative to the strip-cutting path. In one embodiment of the invention, the method further has the step of movably restraining the strip ahead of the cutting.
The step of supporting the strip may further include supporting the strip at an angle θ1 less than the skive angle α on one side of the cutting path and at an angle θ2 greater than the skive angle on the opposite side of the cutting path. This causes the location of the impacted cord to occur approximately at the location wherein the supporting angle changes from θ1 to θ2.
In another embodiment the step of positioning the cutting edge of the ultrasonic knife includes the step of setting a gap distance (d) above the support approximately slightly less than or equal to the thickness of the cord reinforced component, along the region wherein the support is oriented at the angle θ2. The method further includes forming one cut end of the segment wherein a plurality of cords is beneath and adjacent to a flat cut surface.
A segment formed by the method described above results in a first cut end having a cut splicing surface extending outward from the cord reinforced component and a second cut end having a plurality of cords beneath and adjacent to a flat cut surface. The segment, when the first cut end and the second cut end are joined, forms a lap splice having one or more overlapping cords.
An apparatus for cutting segments from a strip of multi-layered elastomeric material containing reinforcing cords, the cords being substantially parallel and more or less oriented in the direction of the cut path, is described by the following features. A cutting element for cutting the strip to form cut ends has a cutting edge oriented to cut along a line 3 , the line 3 being tangent to one or more cords and inclined at a desired skive angle α, and a means for supporting the strip along the cutting path, the means for supporting the strip having a first surface oriented at an angle θ1 less than the skive angle α, and a second surface oriented at an angle θ2 greater than or equal to the skive angle α, and a means for restraining the strip against the means for supporting, the means for restraining the strip preferably lying ahead of the cutting element, and being moveable. The apparatus further has a means for moving both the cutting element and the means for restraining during the cutting of the strip. In one embodiment, the apparatus has the cutting element having a cutting edge inclined at an acute angle β relative to the width of the strip. The cutting edge when oriented as described initiates cutting on the surface furthest away from the means for supporting the strip. The skive angle α is normally set about 10° or less forming a cut path adjacent to one or more cords of the strip being cut. While the means or supporting the strip has two surfaces inclined at angles θ n , and θ2 respectively, θ1 is preferably set about 2° less than the skive angle α, the angle θ2 is about 2° more than the skive angle α. In one embodiment the skive angle α is set to about 8°.
In a preferred embodiment the cutting element is an ultrasonic knife. The cutting element has a planer surface adjacent to the supporting means. The cutting element has a wedge shape increasing in thickness away from the cutting edge.
In a preferred embodiment the means for supporting the strip includes the vacuum-means for adhering the strip to the means for supporting during the cutting procedure.
Definitions
“Aspect Ratio” means the ratio of a tire's section height to its section width.
“Axial” and “axially” means the lines or directions that are parallel to the axis of rotation of the tire.
“Bead” or “Bead Core” means generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers.
“Belt Structure” or “Reinforcing Belts” means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17° to 27° with respect to the equatorial plane of the tire.
“Bias Ply Tire” means that the reinforcing cords in the carcass ply extend diagonally across the tire from bead-to-bead at about 25-65° angle with respect to the equatorial plane of the tire, the ply cords running at opposite angles in alternate layers
“Breakers” or “Tire Breakers” means the same as belt or belt structure or reinforcement belts.
“Carcass” means a laminate of tire ply material and other tire components cut to length suitable for splicing, or already spliced, into a cylindrical or toroidal shape. Additional components may be added to the carcass prior to its being vulcanized to create the molded tire.
“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction; it can also refer to the direction of the sets of adjacent circular curves whose radii define the axial curvature of the tread as viewed in cross section.
“Cord” means one of the reinforcement strands, including fibers, which are used to reinforce the plies.
“Inner Liner” means the layer or layers of elastomer or other material that form the inside surface of a tubeless tire and that contain the inflating fluid within the tire.
“Inserts” means the crescent—or wedge-shaped reinforcement typically used to reinforce the sidewalls of runflat-type tires; it also refers to the elastomeric non-crescent shaped insert that underlies the tread.
“Ply” means a cord-reinforced layer of elastomer-coated, radially deployed or otherwise parallel cords.
“Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire.
“Radial Ply Structure” means the one or more carcass plies or which at least one ply has reinforcing cords oriented at an angle of between 65° and 90° with respect to the equatorial plane of the tire.
“Radial Ply Tire” means a belted or circumferentially-restricted pneumatic tire in which the ply cords which extend from bead to bead are laid at cord angles between 65° and 90° with respect to the equatorial plane of the tire.
“Sidewall” means a portion of a tire between the tread and the bead.
“Skive” or “skive angle” refers to the cutting angle of a knife with respect to the material being cut; the skive angle is measured with respect to the plane of the flat material being cut.
BRIEF DESCRIPTION OF THE DRAWING
The structure, operation, and advantage of the invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying drawings wherein:
FIG. 1 is a schematic view of a multi-component strip ( 1 ) of elastomeric material, showing a path ( 3 ) where the ends of a segment are to be formed;
FIGS. 2 and 3 are detailed views of one type of multi-component strip of elastomeric material shown in FIG. 1;
FIG. 4A is a detailed view of a multi-component cord reinforced elastomeric strip wherein the cords are in a parallel layer oriented at a bias angle relative to the length of the strip;
FIG. 4B is a detailed view of a multi-component cord reinforced elastomeric strip wherein the cords are in a parallel layer oriented at an angle normal to the length of the strip.
FIG. 5A is an edge view of an elastomeric strip showing the forming of the low skive angle surface.
FIG. 5B is an edge view of the preferred method of after impacting a cord and then forming the rest of the low angle skive surface on an elastomeric strip.
FIG. 5C is another edge view of the preferred method of forming the ends ( 12 , 14 ) on the elastomeric strip of FIG. 5B showing the strip separating at the cut ends.
FIG. 6A is a perspective view show in the segment being formed cylindrically about a tire-building drum.
FIG. 6B is a perspective view of the cylindrically formed segment of FIG. 6 A.
FIG. 7 is a perspective view of a first cutting element for forming the low skive angle surface, the preferred first cutting element being an ultrasonic knife.
FIG. 8A is an edge view of the segment first end.
FIG. 8B the second end.
FIG. 8C the cut-to-length segment.
FIG. 9 is a perspective view of the preferred apparatus ( 100 ) or forming the segment.
FIGS. 10A and 10B show a cross-section of the cut ends, 10 B being the joined lap splice.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, a strip of elastomeric material is illustrated in oblique view. The strip ( 1 ) has a transverse width W and an indefinite length designated by the L direction. The strip ( 1 ) is transported upon a conveyor means (not shown) in the direction D. The strip ( 1 ) comprises one or more elastomeric components. The dotted line ( 3 ) shows the location or path of a lateral cut that is to be made across the width of the strip ( 1 ) of elastomeric material from edge 4 a to edge 4 b.
The path ( 3 ) that extends across the width W of the strip ( 1 ) can be perpendicular to the length L of the strip or obliquely traversing across the width W. If the strip ( 1 ) has one or more layers of the parallel cords ( 22 ) that are similarly oriented, then it is preferred that the path ( 3 ) is similarly oriented relative to the cord ( 22 ) path.
In the various figures shown, the elastomeric strips ( 1 ) are various components used in the manufacture of tires. FIGS. 2 and 3, for example, is a detailed view of a multi-component strip ( 1 ) of elastomeric material, the strip ( 1 ) as shown has ply ( 20 ) having a width Wp less than the strip width W, inserts ( 30 ), shoulder gum strips ( 40 ), a liner ( 50 ), a pair of chaffer strips ( 60 ), and a pair of sidewall components ( 70 ). In FIGS. 4A and 4B, multi-component strips are shown. In FIG. 4A, the combination of tire components of FIG. 2 are combined with a bias ply ( 20 ) reinforced by cords ( 22 ) that are parallel and similarly oriented at an oblique angle relative to the length of the ply ( 20 ), generally in an angular orientation of 30° to 65°. In FIG. 4B, the combination tire components of FIGS. 2 and 3 is combined with a ply ( 20 ) having parallel and similarly oriented cords ( 22 ) that are inclined at an angle in the range of 65° to 90° relative to the length of the strip ( 1 ). In FIGS. 4A and 4B, the cords of the multi-component strip ( 1 ) are substantially shorter in length than the path ( 3 ) across the strip. In such a case, the ends of the cords ( 22 ) are not exposed making it very difficult to form a splice end without cutting or damaging a cord ( 22 ). While the inventive method of the present invention is not limited to the creation of splice surfaces for tire components and is readily applicable to any elastomeric strip having tacky surface adhesion properties, for the purpose of discussing the inventive method apparatus, tire components as described above will be used to exemplify the inventive principles of the claimed method and apparatus.
In practicing the invention, it is understood that the forming of the ends ( 12 , 14 ) of a segment ( 10 ) taken from a strip ( 1 ) of elastomeric material is accomplished in a similar way regardless of the component types. This is true if the strip ( 1 ) is reinforced with parallel cords ( 22 ) perpendicular to the strip length or reinforced with bias angled cords ( 22 ).
In practicing the invention, as shown in FIGS. 5A through 5C, a strip ( 1 ) of elastomeric material is shown on an edge view. As shown in FIG. 5A, the preferred method has the strip ( 1 ) supported on a second side ( 4 ) and a cutting element ( 120 ) cutting edge ( 124 ) passes through the strip ( 1 ) along a path that transverses across the entire width of the strip ( 1 ). The cutting element ( 120 ) is positioned to cut at a very low skive angle α of less than 30° relative to the first side ( 2 ) of the strip ( 1 ), preferably the skive angle α is approximately 10° or less.
As shown, the cutting element ( 120 ) is an ultrasonic blade. The ultrasonic blade initiates cutting to one side of the elastomeric strip ( 1 ) while the strip is supported on a supporting means ( 110 ). The supporting means ( 110 ) is preferably an anvil that has an outer surface adjacent to the cord reinforced tire component. This outer surface preferably has a first surface ( 111 ) inclined at an angle of θ1, θ1 being less than the skive angle α. A second surface ( 112 ) is provided wherein the second surface ( 112 ) is inclined at an angle θ2, θ2 being at an angle equal to or greater than the skive angle α. As illustrated, the cord reinforced tire component ( 20 ) is adjacent to the surfaces ( 111 , 112 ). As can be seen, the ultrasonic blade ( 120 ) is positioned at a slight distance (d) spaced above the anvil ( 110 ). That distance creates a gap (d) of approximately 0.0030 inch. This gap (d) is sufficient to allow the cord reinforced tire component ( 20 ) to pass under the ultrasonic blade ( 120 ) during the cutting procedure.
With reference to FIG. 5B, as the ultrasonic blades ( 120 ) transverses through the strip ( 1 ) being cut, the blade ( 120 ) will make initial contact with non cord reinforced components prior to meeting with the cord-reinforced component ( 20 ). The blade ( 120 ) will impact a cord ( 22 ), which results in the cord ( 22 ) being lifted off of the anvil ( 110 ) slightly and thus rides over the blade ( 120 ) over the cutting edge ( 124 ). On the opposite side of the cut, the cords ( 22 ) are pressed under the ultrasonic blade ( 120 ) and occupy the gap (d) that was provided between the anvil ( 110 ) and the blade ( 120 ) for this cutting procedure. As illustrated, three or more cords ( 22 ) are shown adjacent to the flat surface ( 122 ) of the cutting blade ( 120 ). The ability of the cords ( 22 ) to be lifted over the blade ( 120 ) permits the ultrasonic knife blade ( 120 ) to pass through the cords ( 22 ) without cutting any of the cords ( 22 ). This is true because of the separation of the cut ends ( 12 , 14 ) is created by the sharp cutting edge ( 121 ) of the blade ( 120 ). By combining the rate of speed at which the blade ( 120 ) is moving and the fact that the cords ( 22 ) are a more resistant material than the elastomeric rubber, it is possible to easily cut through the rubber without damaging the cords ( 22 ). As illustrated in FIG. 5C, once the blade ( 120 ) is interposed between two adjacent cords ( 22 ) the cut surface ( 6 ) riding over the blade ( 120 ) is allowed to ride freely upward and is lifted slightly. This prevents the cut surface ( 6 ) of end 14 from reattaching itself to the other cut end ( 12 ) of the elastomeric strip ( 1 ).
As shown in the invention, all the cutting is shown with the components lying in a horizontal direction and being cut from the top. It should be noted that in normal cutting and for simplicity of tire building it is sometimes desirable, even preferable to invert these strips such that the entire figure could be inverted relative to the ground and that the cutting is actually occurring from below the surface upward. For purposes of this invention, however, it is sufficient to note that these materials can be cut from either direction as shown or in an inverted position cutting from the underside.
As illustrated in the FIG. 5C, the ultrasonic blade ( 120 ) itself provides a key feature in enabling the strip to be cut in such a fashion that one end ( 14 ) of the cut segment ( 10 ) lifts and rides over the blade ( 120 ) as the blade ( 120 ) traverses through the strip while the other cut end ( 12 ) is actually held down by the blade ( 120 ) as the blade is making the cut. As illustrated, one cord ( 22 ) is generally snagged or raised off the anvil ( 110 ) slightly as the cutting blade ( 120 ) enters the ply edge. This snagged cord ( 22 ) often times can be slightly bent even pulled out from the cut ends ( 12 , 14 ). It has been determined in tire building that this cord ( 22 ) is of no consequence to the tire's structural integrity in that when the cord is snagged or bent, that portion of the impacted cord ( 22 ) will lie on the turn-up side of a bead and is not part of a structural component of the tire or the working component of the tensioned ply because the bend portion of the impacted cord lies at the radially outer portion of the ply turn up. It is important, however, that the cord ( 22 ) that is snagged does not prevent good uniform splicing. It has been found by having the cutting edge ( 121 ) of the cutting element ( 120 ) inclined at an acute angle of approximately 60° or less relative to the width of the ply, the cutting initials from the top surface to the anvil supported surface and can be accomplished with minimal damage to the one impacted cord ( 22 ).
It has been found that by transitioning the support ( 110 ) from an angle θ1 at one surface ( 111 ) to θ2 at the other surface ( 112 ) and fixing the gap (d) at the transition location ( 114 ), one can predict where the cord ( 22 ) impact with the blade edge 121 will occur rather repeatedly. This is important in establishing a precise length of the cut segment ( 10 ). As shown in the cross sectional view of the segment ( 10 ), the cutting blade ( 120 ) has a flat surface ( 122 ) and the lower portion or second side ( 4 ) of the strip ( 1 ) adjacent to the support ( 111 ) at surface ( 112 ) is inclined at an angle θ2 is approximately equal to the lower inclination of the surface ( 122 ) of the cutting blade ( 120 ) ensures that the elastomeric strip ( 1 ) is cut in such a fashion that a flat surface ( 8 ) occurs directly above two or more preferably three or more of the ply cords ( 22 ). This effectively filets the elastomeric material directly above the ply cords, exposing these ply cords ( 22 ) to a flat cut surface ( 8 ). This flat cut surface ( 8 ) greatly facilitates the ability to create an overlapping splice joint ( 15 ) in tire building. This overlapping splice joint heretofore was hindered by the elastomeric components being directly above the lapped ply cords ( 22 ). By removing this material, in this unique cutting fashion it is possible to create an overlap cord splice ( 15 ) that is stronger than other splices used in radial tire building. It is well known that when the cord splices ( 15 ) are overlapped, one can insure a stronger lap spliced joint. Heretofore, these lap splice joints were avoided due to the fact that the multi-layered components would create too much mass imbalance at the lap splice ( 15 ) due in part to the amount of material directly above the cord ( 22 ). In attempts to reduce this problem, the skive angle α was reduced to a very low angle of 10° or less. Nevertheless, this resulted in still too much material at the lap splice joint creating a slight mass imbalance. Therefore, it had been recommended in the past to create butt splices such that the cords ( 22 ) to not overlap. While this prevented the problem of mass imbalance, it creates generally a more difficult splice to repeatedly make in mass production. This is true because the variation in length between the cut end ( 12 , 14 ). If the segment ( 10 ) varies in length by only a few thousandths of an inch, cord spacing can be affected. Overlapping the splice cords prevents this from being an issue. The present invention permits multi-layered components to be lap spliced with overlapping cords without creating an undue mass imbalance. This is due to the fact that the ply ( 20 ) as it is being cut is allowed to lift such that the elastomeric material above the cutting element ( 120 ) is removed forming a flat cut surface ( 8 ) for approximately a length of three or more cords ( 22 ) as shown in the illustrated embodiment of FIG. 5 C. This permits lap splices ( 15 ) to be done effectively and efficiently. What is unusual is that this can be accomplished without additional cutting or additional steps. All cutting is done in one simple operation of passing the ultrasonic blade ( 120 ) through the multi-layered component or strip ( 1 ).
With reference to the supporting means ( 110 ), it is shown that the supporting means is angled as previously discussed, the first outer surface ( 111 ) is inclined at a first angle θ1 and the second outer surface ( 112 ) is inclined at a second angle θ2. Internal of the supporting means ( 110 ) preferably are a plurality of holes ( 116 ) that intersect the surfaces ( 111 , 112 ) and are connected to vacuum system. This vacuum system helps keep the strip ( 1 ) secure to the support during the cutting procedure and helps assist in this matter. To further assist and holding the elastomeric strip ( 1 ) in place during the cutting procedure a retraining means ( 130 ) is provided just ahead of the cutting element ( 120 ). This restraining means ( 130 ) as illustrated, is a wheel ( 132 ) that rotates and is moveable along the same path as the cutting means ( 120 ). This wheel ( 132 ) traverses directly in front of the cutting path ( 3 ) but is at a sufficient distance to enable the strip ( 1 ) to lift and pass over the cutting blade ( 120 ) as the blade is traversing.
With reference to FIGS. 6A and 6B, the joining of the splice ends ( 12 , 14 ) occurs when the cut-to-length segment ( 10 ) is cylindrically formed around a tire building drum ( 5 ) as illustrated. As shown, the tire builder ideally brings the cut surfaces ( 12 , 14 ) together in a lapping splice relationship along a common plane P. This precisely sets the circumferential length of the segment. The surfaces ( 6 , 8 ) are then pressed together in a technique commonly referred to as stitching.
The apparatus ( 100 ) has a means ( 120 ) for forming a low angle skive surfaces across the width of the strip. The means preferably is a cutting element ( 120 ). In the most preferred apparatus the cutting element ( 120 ) is an ultrasonic knife. As shown in FIG. 7, the knife ( 120 ) preferably has a somewhat wedge like shape with a cutting edge ( 121 ) that is oriented at a fixed angle alpha relative to the strip cut path ( 3 ) and is also canted at an angle β such that the cutting edge ( 121 ) is inclined slightly at an acute angle relative to the width of the ply. This dual angle setting of the cutting element ( 120 ) achieves a superior more uniformed cut because the knife's cutting edge ( 124 ) is really the tip of a chisel type-cutting tool. Unlike a conventional ultrasonic low amplitude high frequency knife that cuts along a side of the blade, the chisel type blade has no node along the cutting edge ( 121 ) because the cutting edge ( 121 ) is really the tip of the blade tilted and canted slightly. This means that the excitation frequency is traveling in the same distance all along the cutting edge ( 121 ). This fact enables the rubber to be cut more uniformly than conventionally by standard ultrasonic blade type cutters.
A second feature, the preferred apparatus ( 100 ) is a means for moving the means ( 120 ) for forming and the means ( 130 ) for restraining. The means ( 140 ) for moving preferably has a motor driven mechanism that slidedly traverses the means ( 120 ) for forming and the means ( 130 ) for restraining across the width of the strip ( 1 ). The means ( 120 ) ideally can be moved angularly relative to the strip length to accommodate cutting along any bias angle.
The means for moving ( 140 ) may also include a means 141 for orienting the cutting element ( 120 ) at a range of angles to achieve the optimum skive surface area. As shown in FIG. 9, the prefer apparatus ( 100 ) may include a conveyor means ( 150 ) to advance the strip ( 1 ) along the direction of the strip ( 1 ) length preferably the conveyor means ( 150 ) would be capable of advancing the strip ( 1 ) to a predetermined distance to enable the strip ( 1 ) to be cut to form a segment ( 10 ) having a fixed length L between the cut surfaces ( 12 , 14 ) at a location S 1 and S 2 as previously shown.
Once cut, the segment ( 10 ), when spliced has the cut ends ( 12 , 14 ) joined and the strip ( 1 ) cylindrically forms a tire as previously discussed. The segment ( 10 ) as shown in FIGS. 8A, 8 B and 8 C can be thick, thin, flat, or irregularly contoured, a single cord reinforced component ( 20 ) or a multi-component as discussed. The angular orientation of the surfaces ( 6 , 8 ) relative to a normal plane NB can be selected for optimum lap joint splicing for the particular strip as shown in FIGS. 10A and 10B.
While the strip may include some cured or partially cured components, it is preferred that portions of this strip ( 1 ) be uncured or at least partially uncured. This permits the spliced surfaces ( 6 , 8 ) to exhibit the tacky, self-sticking properties to facilitate joint adhesion at the lap splice ( 15 ). While certain representative embodiments and details have been shown for the purpose of illustrating the invention will be appreciated there is still in the art various changes and modifications may be made therein without departing from the spirit or scope of the invention.
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A method of an apparatus for cutting segments ( 10 ) to desired lengths from a strip ( 1 ) of elastomeric tire components having at least one cord reinforced component involves the step of impacting one cord ( 22 ) as the cut is being made and lifting the cord ( 22 ) to avoid cutting cords ( 22 ) while directing the cutting path along the lifted cord( 22 ). The article resulting from the method has a plurality of cords ( 22 ) adjacent a flat cut splicing surface ( 8 ) suitable for lap splicing.
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BACKGROUND OF THE INVENTION
This invention relates to a single purpose implement, this purpose being to cut and match "grouted-tile-pattern" vinyl sheet floor covering, commonly referred to as `linoleum roll stock`, so that pieces of stock may be abutted longitudinally, precisely matching the pattern but without showing the "joint" (that is, the line along which adjoining pieces of stock are longitudinally joined). By "grouted-tile-pattern" stock, I refer to linoleum in which individual tiles are laid out geometrically and grouted between each tile so as to form a "field" of repeating geometrical patterns such as are disclosed in product catalogues of manufactures of such rolled stock, for example Armstrong, Congoleum, G.A.F., Mannington Mills, Biscayne Corporation, and the like, the patterns from which catalogues are incorporated by reference thereto as if fully set forth herein.
More specifically, I refer to linoleum roll stock with simulated grouted tile patterns which stock is normally available in rolls either 6 feet wide or 12 feet wide, and of arbitrary length. Some roll stocks are quite flexible, with considerable "give" (referred to as "cushioned floors"), while other are relatively stiff (referred to as "inlaid floors"). Such roll stock to which this invention applies closely duplicates the visual impact of (a) ceramic tile floors in which individual tiles are separated by a cementitious material ("grouting"), or (b) brick or stone floors in which individual bricks or stones are separated by grouting. As is well known, ceramic tile floors are extremely durable and have a timeless beauty peculiar to such floors in which tiles are manually set and grouted in substantially uniform relationship with each other. It is this substantially uniformly spaced apart relationship, which, because it is not perfectly uniform imparts the characteristic "look" of a manually laid tile floor.
As presently conventionally done, a pair of linoleum sheets ("roll-portions") are longitudinally matched by an average linoleum flooring installer ("floor mechanic") who cuts the "salvage edge" while kneeling on the linoleum and measuring the width of the stock along a line he wishes to cut. He then marks the linoleum at several locations, longitudinally, with the blade of the cutting knife, or a colored pencil, places a straight edge along the marks and cuts the roll longitudinally for a distance of from 2 to 3 feet. He then moves himself on his knees along the straight edge without moving it, and continues the cut for another 1 or 2 feet, having thus made a cut of about 4 feet in total length without moving the straight edge. He then makes additional measurements and repeats the process to make a continuous incision as he moves intermittently along the length of the stock. Instead of measuring and marking the linoleum, he may overlap a first and second roll-portion (or "sheet") so that the "field" is matchingly repeated, and he then cuts both portions simultaneously so that they have a common linear edge which may be abutted without showing the joint. Though overlapping and cutting two sheets simultaneously solves the problem of obtaining a flush joint, and matched in this sense, the problem of matching the field precisely, remains, since he cannot see the precise width of grouting to be left on the bottom sheet when it is overlapped with a second sheet. How accurately he makes the longitudinal cut, both with respect to obtaining a flush joint, and, a precisely matched field, irrespective of which method he uses, will determine how well he solves the problem of "hiding" the joint he makes.
This problem of forming a matching joint between a first and second roll-portion of a pair of linoleum roll-portions has been addressed over a period of decades and numerous solutions have been proffered. None has been addressed to the specific problem of satisfactorily matching longitudinal grouting patterns in grouted-tile-pattern roll stock.
For example, U.S. Pat. No. 2,383,368 teaches a device for making a beveled straight lateral cut, but there is no provision for visually inspecting the lateral portion of the stock being cut, which lateral portion is contiguous to the cut edge. The most notable feature of the device is that it permits cutting with a blade without the blade being drawn against a guiding straight edge. As will be evident, if a blade is drawn against a straight edge made of steel or other hard material the blade will tend to be dulled more quickly than if it was cutting only the linoleum. Stated differently, once the longitudinal path is set along which the holder of the blade is to traverse, there is no means for visually determining the precise line along which the blade is cutting, until after the "blind" cut is made. It will be evident that it is more preferable to be able to observe the precise line to be cut, before it is cut, and to make such adjustments as might be deemed necessary. It will also be evident that it would be preferable not to use a blade holder because of the error that is introduced in mounting the blade, and then preserving its mounting accurately while the blade is being used.
U.S. Pat. No. 2,487,237 discloses a device which allows the line of cutting to be inspected visually just before the cut is made and if the machine is guided along a straight edge, it would be capable of making a longitudinal cut in the roll stock. The adequacy of the cut, judged by how well the pattern is matched and the joint between adjoining sheets of linoleum is hidden, will depend upon the expertise of the cutter and the steadiness of his hand, not to mention other factors such as the sharpness of the blade, inter alia.
The cost of the machine such as is disclosed in the +237 patent militates against its use by a floor mechanic with normal financial resources, and the maintenance and operation of such a machine is beyond the ordinary skill of a floor mechanic. There is a pressing need for a simple and inexpensive implement which will faciliate the laying of grouted-tile-pattern linoleum roll stock because the implement is efficient, easy to use quickly, and accurate to make an incision manually with a blade, along a longitudinal grout line in the salvage edge so as to enable a pair of adjoining linoleum sheets to be joined precisely without noticing the joint. The device of this invention is such an implement. I know of no prior art device which permits a flooring man to lay a floor with grouted-tile-pattern linoleum roll stock as simply, effectively and easily as the device of my invention.
SUMMARY OF THE INVENTION
It has been discovered that the problem of matching first and second roll-portions of grouted-tile-pattern linoleum roll stock along the longitudinal edges thereof, so as to maintain the overall repeating grouted-tile pattern without showing the joint, stems for the most part from (a) an inability to visually align a boundary of a linearly continuous simulated grouting before cutting through it to match another boundary, as is the case with overlapping edges of sheets and cutting through them, and (b) errors in measuring and marking one of the sheets and cutting through the marks.
It is therefore a general object of this invention to provide an implement for grouted-tile-pattern linoleum roll stock which implement comprises a combined visual gauge and guide laminar member of relatively thin metal having see-through rectangular apertures, serving as "sights", which member permits a manually operable blade means to be moved along its exterior longitudinal edge which is nearer the apertures, so as to cut the stock. The cut salvage edge of stock is left with a vertical face which facilitates precise abutment for a hidden joint.
A specific object of this invention is to provide a remarkably simple implement for cutting grouted-tiled-pattern linoleum roll stock along a longitudinally continuous grout line with a manually operable blade means, by making no measurement other than visually inspecting the width of the grout line through spaced apart apertures in an elongated relatively thin metal laminar strip member, and positioning its longitudinal edge, nearest the apertures, on the salvage edge in such a way as to leave a predetermined width thereof when cut with the blade's manually guided edge.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects and advantages of my invention will appear more fully from the following description, made in connection with the accompanying drawings, of a preferred embodiment of the invention, wherein like reference characters refer to the same or similar parts throughout the several views, and in which:
FIG. 1 is a perspective view from a slight elevation of the device of this invention as used to cut grouted-tile-pattern linoleum roll stock.
FIG. 2 is a plan view of a combination visual gauge and metal guide member, showing rectangular apertures spaced apart from the nearer longitudinal edge by a marginal portion.
FIG. 3 is a plan view of a portion FIG. 2, shown in enlarged detail, with the visual gauge and guide member placed on a longitudinal salvage edge of roll stock, after a predetermined width of salvage has been trimmed, showing the inner boundary of the remaining portion of salvage visible in the apertures.
FIG. 4 is a cross section along the lines 4--4 in FIG. 3 showing reference marks scored in the metal separating successive apertures.
FIG. 5 is a cross sectional view along the line 5--5 showing a portion of FIG. 3, between apertures, in which the reference marks are scored in the metal.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
A detailed description of the invention is desirably preceded with a definition of the problem solved by the invention, referring particularly to a typical grouted-tile-pattern in linoleum roll stock, a portion of which is illustrated in FIG. 1. There is schematically shown, in slightly elevated, perspective view, the implement of this invention being used to trim a longitudinal "salvage" edge of a first roll-portion 10 of stock which is to be abutted against a longitudinal edge of a second roll-portion of stock (not shown). Numerous patterns of grouted tile are available, but what they all have in common is a linear, either continuous or interrupted grouting along a salvage edge which is to be joined to another roll-portion without showing the joint, and without disrupting the overall repeating pattern ("field").
Typically, this longitudinal salvage edge of linoleum stock has embossed or otherwise imprinted on its surface, a linearly continuous simulated grouting ("grouting" for brevity) indicated by reference numeral 11, which grouting is too wide to be abutted, as is (without being trimmed), against a longitudinal salvage edge of a second roll-portion of the same stock. The combined width of the longitudinal grouting in the patterns of the abutted roll-portions would be too wide and inappropriate in the overall field. Therefore, a portion' (trimmed portion) of the salvage edge 11 is to be longitudinally trimmed so as to leave a portion 11" (remaining portion) which is the precise width required to duplicate the width of grouting (at that joint), so as to fit in the field precisely. This is normally done by manually cutting through the salvage edge 11 with a blade means 12 which is drawn against a conventional straight edge, appropriately located in the usual manner, so as to align its edge with marks made in the linoleum. The problem is to leave precisely the right width of remaining portion 11" so that the longitudinal edges of the first and second roll-portions can be satisfactorily matched without making any measurement, other than visual, and without making any marks in the linoleum before it is trimmed. If this can be done without sacrificing accuracy, it would save time which is a critical economic factor in laying linoleum roll stock.
The foregoing problem has been solved by the implement of this invention, shown in plan view in FIG. 2, which includes a combined visual gauge and guide member, indicated generally by reference numeral 13, having a longitudinal edge 14 against which blade means 12 is held and drawn. this edge 14 is the guiding edge for the blade and the only guiding edge for cutting, because of its specific relationship to the apertures 15, described in greater detail hereinafter.
The member 13 is a laminar, elongated, generally rectangular metal strip of bronze or ferrous metal, preferably stainless steel, having a thickness in the range from about 0.02" (inch) to about 0.25", and at least 3' (feet) long. More preferably the member 13 is from about 3' to about 6' long, and most preferably about 4' long. The member cannot be made from soft metal or a synthetic resinous material because it will not be essentially immune to damage from the blade during use, and it cannot practically be constructed of transparent glass which is frangible and ill-suited for commercial use. Further, synthetic resins, whether opaque or not, are prone to distortion over a period of time, and it is critical that the longitudinal edge 14 of the member 13 be straight.
The width of the member 13 is necessarily at least 1" wide so as to be able to locate the member on the linoleum by exerting a downward force on it, and more preferably from about 2" to 5" wide to allow the member to be located by kneeling on it. The thickness of the member is such that it is flexible enough to follow closely any unevenness in the surface of the linoleum, though it is also essential that the member 13 be relatively thin to prevent its edges from casting a distracting shadow on the linoleum, which shadow would make it difficult to see where the cut is to be made, and how well the desired portions of the tile pattern are matched, before the cut is made. For the best joint "fit" it is desirable that the manually made cut be vertical, that is, have a vertical, unbeveled face.
Near one longitudinal edge 14, the member 13 is provided with a plurality of longitudinally spaced apart rectangular apertures 15, this edge being the edge against which the blade means 12 is to be drawn. The edge 14 is critically linear within a tolerance of ±0.010" over the entire length of the member. The other edge 16 provides no particular critical purpose. One aperture edge 15' (longitudinal edge of aperture 15) is spaced apart from the longitudinal edge of the member 13 by a distance which corresponds to the narrowest grouting width in the field, typically 0.1875", and the longitudinal edges 15' of all the apertures 15 are aligned so as to be parallel to longitudinal edge 14 of the member 13. The purpose of the row of aligned apertures is to be able to see the inner boundary 18 of the grouting 11 therewithin, so as to visually determine pecisely where the longitudinal edge 14 of the member 13 is to be located. The width of each aperture is not critical provided it is wide enough to examine the inner boundary 18 of the grouting 11 to be trimmed. Typically the apertures are from about 0.375" to about 0.5" wide and from about 0.5" to about 6.0" long, and when their edges 15' are aligned, as they must be, they will provide a narrow marginal portion 17 of uniform width in the member 13 which marginal portion has a width corresponding to the minimum thickness of grouting in the tile pattern, as mentioned hereinabove.
Since it is critical that the aperture edges 15" be located visually so as to display a preselected amount of grouting within the apertures, and to align this display within the serially aligned plural apertures so as to have the precise width of remaining portion 11" of grouting, it is essential that the inner boundary of the salvage edge be visible within the apertures where the inner boundary of the salvage edge be visible within the apertures where the inner boundary can be properly aligned before the member 13 is located for making the cut. To assist in aligning the inner boundary, one or more reference marks 21, 22 and 23 are provided, longitudinally, between the apertures, for substantially the entire length of the member 13, as is illustrated in FIGS. 4 and 5, should the width of grouting 11" be greater than the width of the marginal portion 17. Fewer reference marks may be provided, but it is desirable to have marks at each end of the member 13, and at each end of each set of apertures. As is more readily evident in FIG. 3, inner boundary 18 is aligned with reference mark 22 across the length of each aperture, before a cut is made.
Since member 13 is a combined visual gauge and guide with no quantitatively fixed measuring marks such as divisions for fractions of an inch, or centimeter thereon, it carries only the reference marks which correspond to the widths of grouting usually and commonly provided in grouted-tile-pattern linoleum roll stock. To observe the reference inner boundary of a salvage edge effectively, it is necessary to have an aperture at least every 6" so as to facilitate sighting of the reference inner boundary. An effective arrangement of "sights" is to provide relatively small apertures about 1" long and about 0.25" wide in repetitively spaced apart groups of two and four apertures, as shown in the drawing. If desired, plural wider apertures may also be provided for those instances where it might be desired to sight a wider portion of a relatively wide salvage edge.
One end of member 13 is provided with a 45° wedge 19 to facilitate pivoting the member 13 about the wedge's point, when the point is placed against a base of a wall surface.
To use the implement of this invention, a flooring man simply lays the member 13 on the field and aligns the cutting edge 14 of the marginal portion 17 along the outer boundary of the field grout line. He now observes where the inner boundary of the grout line is aligned relative to the reference marks 21, 22 and 23, or relative to the longitudinal edges of the apertures. He notes which particular reference mark (say 22) is aligned with the inner boundary of the field grout line, and this determines the width of the grout line to be cut from the salvage edge. He then transfers the member 13 to the salvage edge and aligns the inner boundary of the grout line at this edge with the noted reference marks 22. He then locates the member by exerting a force on it, preferably by placing his knee on it, then manually makes an incision with a sharp cutting blade 12 along the longitudinal edge of the member 13, which edge is nearest the aligned apertures 15, without moving the member, for a distance through which his arm can comfortably travel while making the incision. He then moves himself along the member, on his knees, without moving the member, and continues the cut for substantially the entire length of the member. He then moves the member longitudinally while aligning its longitudinal edge 14 (nearest the apertures) with the incision made, and then again fixedly locates the member, as before, and repeats the process step of making an incision along the line until a sufficient length of the first roll-portion is cut to match a corresponding length of a second roll-portion to which it is to be joined.
Typically, a floor mechanic will determine the width of grouting he desires (by the procedure described hereinabove) and trim the excess from the salvage edge of the first roll-portion. Since the second roll portion of stock which is to be abutted to the trimmed first portion will not require any grouting, (the first roll portion already having the precise width required by the field), the entire width of grouting will be trimmed ffrom the salvage edge of the second roll portion. When the first and second roll portions are abutted, the pattern of the field will have been precisely matched and the joint will be effectively hidden. It will be evident to a floor mechanic that, should the need arise, he may just as easily trim a portion of the grouting from the salvage edge of the second roll portion, and all the grouting from the first roll portion; or, if the need arises, he may leave a portion of the required width of grouting on the first roll portion and then trim the grouting on the second roll portion to have a sufficient width so that when the first and second roll portions are abutted, the desired width of grouting in the field will have been duplicated.
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This invention is directed to solving the problem of matching first and second roll-portions of grouted-tile-pattern linoleum roll stock along the longitudinal edges thereof, so as to maintain the overall repeating grouted-tile pattern ("field") without showing the joint. The problem is solved by a remarkably simple implement for cutting the grouted-tiled-pattern linoleum roll stock along a longitudinally continuous grout line with a manually operable blade means, by making no measurement other than visually inspecting the width of the grout line through spaced apart apertures in an elongated relatively thin metal laminar strip member, and positioning its longitudinal edge, nearest the apertures, on the salvage edge in such a way as to leave a predetermined width thereof when cut with the blade's manually guided edge.
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The present application claims priority under 35 U.S.C. §119 to Korean Patent Application Nos. 2000-49908 filed on Aug. 26, 2000; 2000-69366 filed on Nov. 21, 2001; and 2001-09384 filed on Feb. 23, 2001, the contents of which are all herein incorporated by reference in their entirety for all purposes.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radio-frequency (RF) matching unit, and more particularly to an RF matching unit having a variable inductor which facilitates variable control, for use in a high frequency and high power application, such as for coupling RF power to a plasma within a plasma reaction chamber of a semiconductor wafer processing system and the like.
2. Description of Related Art
A plasma enhanced semiconductor wafer processing system generally includes a plasma reaction chamber within which certain plasma enhanced processes are performed on a semiconductor wafer. To produce a plasma within the reaction chamber, a reactant gas is pumped into the chamber and a high power RF signal is coupled to the gas. The RF energy excites the reactant gas and produces a plasma within the chamber.
To uniformly maintain the plasma at a level which the plasma enhanced processes require, the RF energy has to be supplied stably to the chamber. For this purpose, an RF matching unit is used to match impedance of an RF generator to the impedance of the chamber atmosphere. However, since the impedance of the chamber atmosphere is time variant, the RF matching unit must be dynamically tuned to maintain the impedance match.
A conventional RF matching unit generally includes a variable inductor having a spiral shaped fixed coil and a plurality of rotating shield blades. Each of shielding blades is interspersed between each pair of coil turns of the fixed coil. To tune inductance of the variable inductor, the position of the shielding blades is controlled by using a position feedback technique well known in the art. However, it takes a long time for an RF match between the RF generator and the chamber to be achieved, and the variable inductor generates a large amount of heat. Also, since current flow through the fixed coil is shielded according to a rotated angle of the shielding blades, the shielding blades are apt to be heated. As a result, surfaces of the shielding blades are often oxidized to generate arcs, increasing contact resistance of contact portions of the variable inductor, thereby deteriorating RF match efficiency. Particularly, in the case that the shielding blades formed of metal material are oxidized, the time needed to achieve the RF match is lengthened to an even greater extent.
Also, when the shielding blades that are heated are used for a long time, a silver film coated on the surfaces of the shielding blades can be transformed into a carbon film, which deteriorates the ability of the shielding blades to shield the magnetic field of the fixed coil. To reduce the drop in shield efficiency of the shielding blades due to the heat, there is proposed a method of forming the fixed coil by using a material having a low heat loss characteristic. However, in this case, there is a problem in that the inductance of the material is relatively small, and thereby RF match efficiency is deteriorated.
SUMMARY OF THE INVENTION
The present invention is therefore directed to providing an improved RF matching apparatus which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art.
It is an object of the present invention to provide an improved RF matching apparatus having an inductor which generates relatively small heat, has a long life, and prevents arcs from being generated.
It is another object of the present invention to provide an improved variable inductor which facilitates variable control, and which is adaptable for use in high frequency and high power applications.
These and other objects are provided, according to the present invention, by an apparatus for matching the impedance of an RF generator to the impedance of an RF load for use in manufacturing semiconductor devices by using a plasma, comprising a variable inductor coupled to a variable capacitor and an invariable capacitor. The variable inductor having two inductors coupled electrically with each other and disposed adjacent to each other. At least one of the two inductors is disposed movably to make the magnetic flux of the one inductor interfere with the magnetic flux of the other inductor, thereby to control the inductance of the variable inductor.
According to an RF matching apparatus of one embodiment of the present invention, the two inductors include a fixed inductor formed of an oval and spiral shaped coil having a given number of coil turns, and a rotating inductor formed of an oval and spiral shaped coil having a given number of coil turns and disposed rotatably at the magnetic flux of the fixed inductor. The inner diameter of the fixed inductor is larger than the outer diameter of the rotating inductor. The rotating inductor is rotatably disposed upward or downward from the fixed inductor, or the rotating inductor may be disposed in the fixed inductor. Alternatively, the inner diameter of the rotating inductor may be larger than the outer diameter of the fixed inductor, whereby the fixed inductor is disposed in the rotating inductor. The combined magnetic flux of the fixed and rotating inductors is increased or decreased according to a rotated angle of the rotating inductor.
Each of the coils may be formed of a conductive pipe and a plurality of conducting wires disposed in the conductive pipe. Also, the conductive pipe may be formed of conductive material, for example copper (Cu) or aluminum (Al). A surface of the conductive pipe may be coated with gold or silver having good conductivity. Alternatively, each of the coils can be formed of a single conductive wire having the same diameter as the conductive pipe.
The RF matching apparatus of one embodiment of the present invention further includes a transfer unit that moves the rotating inductor toward and away from the fixed inductor. Accordingly, overlapping width between the fixed and rotating inductors may be increased, so that the inductance value of the variable inductor may be controlled at a greater width.
Also, the RF matching apparatus of one embodiment of the present invention includes a fixing unit that fixes coil turns of the coils in a spaced-apart relation to one another. The fixing unit includes ‘E’ shaped rings disposed at regular intervals between the coil turns of the coils. Each of the ‘E’ shaped rings is designed to have a minimized capacity to thereby not have influence on the magnetic field generated by the rotating and fixed inductors.
Also, the RF matching apparatus of one embodiment of the present invention includes connection members at connecting portions between the coils, or between the coils and the capacitors. Each connection member is composed of a gripper having semi-arc shaped gripping portions, and a locking member for fastening the gripping portions.
According to an RF matching apparatus of another embodiment of the present invention, the two inductors include a band type rectangle and whirl shaped fixed coil, and a band type rectangle and whirl shaped rotating coil having a rotating axis penetrating the fixed coil. An output end of the fixed coil is coupled electrically with an input end of the rotating coil. An input end of the fixed coil and an output end of the rotating coil are coupled electrically with the output end of the variable capacitor and the input end of the invariable capacitor, respectively. The combined magnetic flux of the fixed and rotating coils is increased or decreased according to a rotated angle of the rotating coil.
According to an RF matching apparatus of another embodiment of the present invention, the two inductors include a band type rectangle and whirl shaped fixed coil, and a band type rectangle and whirl shaped moving coil disposed movably in parallel to the fixed coil. The fixed and moving coils are positioned to be spaced apart from each other and opposite with respect to each other. An output end of the fixed coil is coupled electrically with an input end of the moving coil. An input end of the fixed coil and an output end of the moving coil are coupled electrically with the output end of the variable capacitor and the input end of the invariable capacitor, respectively. The combined magnetic flux of the fixed and moving coils is varied according to overlapping width between the fixed and moving coils controlled by moving the moving coil.
According to an RF matching apparatus of another embodiment of the present invention, the two inductors are a circular and spiral shaped fixed coil having a given number of coil turns, and a circular and spiral shaped moving coil disposed from the fixed coil upward to be moved up and down, thereby to be overlapped with or separated from the fixed coil having a given number of coil turns. The coil turns of the fixed coil are formed to have winding width enough to be interspersed between each pair of coil turns of the moving coil. An output end of the fixed coil is coupled electrically with an input end of the moving coil. An input end of the fixed coil and an output end of the moving coil are coupled electrically with the output end of the variable capacitor and the input end of the invariable capacitor, respectively. The combined magnetic flux of the fixed and moving coils is varied according to overlapping width between the fixed and moving coils controlled by moving the moving coil up and down.
According to an RF matching apparatus of another embodiment of the present invention, the RF matching apparatus comprises a variable inductor having a band type rectangle and whirl shaped fixed coil, and a rectangle shaped magnetic shield rotating plate disposed in the fixed coil and having a rotating axis penetrating the fixed coil. Input and output ends of the fixed coil are coupled electrically with the output end of the variable capacitor and the input end of the invariable capacitor, respectively. The magnetic flux of the variable inductor is varied according to a rotated angle of the magnetic shield rotating plate.
According to an RF matching apparatus of another embodiment of the present invention, the RF matching apparatus comprises a variable inductor having a circular and spiral shaped fixed coil having a given number of coil turns, and a circular shaped magnetic shield rotating plate disposed rotatably at the magnetic flux of the fixed coil and having rotating axes formed on both sides thereof Input and output ends of the fixed coil are coupled electrically with the output end of the variable capacitor and the input end of the invariable capacitor, respectively. The magnetic flux of the variable inductor is varied according to a rotated angle of the magnetic shield rotating plate.
According to an RF matching apparatus of another embodiment of the present invention, the RF matching apparatus comprises a variable inductor having a circular and spiral shaped variable coil, a mounting plate for mounting the variable coil, and a moving bar for adjusting the length of the variable coil and being fixed to one end of the variable coil through the center of the mounting plate and the variable coil. The other end of the variable coil is fixed to the mounting plate. Both ends of the variable coil are coupled electrically with the terminal of the variable capacitor and the input end of the invariable capacitor, respectively. The magnetic flux of the variable inductor is varied according to a length of the variable coil controlled by moving the moving bar.
As described above, the apparatus of the present invention can vary the magnetic flux, i.e., the inductance of the variable inductor by changing relative position, for example the relative angle or the relative distance between two coils or between a coil and a magnetic shield plate forming a variable inductor. Also, the apparatus of the present invention can vary the magnetic flux of the variable inductor by changing length of a magnetic coil with a given number of coil turns forming a variable inductor.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
FIG. 1 is a schematic diagram showing a general circuit of an equipment using a RF matching unit.
FIG. 2 is a perspective view of an RF matching unit in accordance with a first embodiment of the present invention.
FIG. 3 is a perspective view showing a connecting member between components of the RF matching unit shown in FIG. 2 .
FIG. 4 is a perspective view of an ‘E’ shaped ring for spacing out and fixing coil turns of conductive pipes forming a rotating inductor and a fixed inductor of the RF matching unit shown in FIG. 2 .
FIG. 5 is a partial perspective view showing a portion of the conductive pipe and conducting wires of the rotating and fixed inductors of the RF matching unit shown in FIG. 2 .
FIG. 6 is an exploded perspective view of a wire connecting portion of the rotating inductor shown in FIG. 2 .
FIG. 7 is a perspective view showing a different form of the variable inductor of the RF matching unit shown in FIG. 2 .
FIG. 8 is a schematic perspective view showing a variable inductor of an RF matching unit in accordance with a second embodiment of the present invention.
FIG. 8A illustrates an example of the manner in which the coils of FIG. 8 are electrically coupled together.
FIG. 9 is a graph showing the inductance characteristic of the variable inductor of the RF matching unit shown in FIG. 8 .
FIG. 10 is a perspective view showing a variable inductor of an RF matching unit in accordance with a third embodiment of the present invention.
FIG. 11 is a graph showing the inductance characteristic of the variable inductor of the RF matching unit shown in FIG. 10 .
FIG. 12 is a perspective view showing a variable inductor of an RF matching unit in accordance with a fourth embodiment of the present invention.
FIG. 13 is a perspective view showing a variable inductor of an RF matching unit in accordance with a fifth embodiment of the present invention.
FIG. 14 is a graph showing the inductance characteristic of the variable inductor of the RF matching unit shown in FIG. 13 .
FIG. 15 is a perspective view showing a variable inductor of an RF matching unit in accordance with a sixth embodiment of the present invention.
FIG. 16 is a perspective view showing a variable inductor of an RF matching unit in accordance with a seventh embodiment of the present invention.
FIG. 17 is a graph showing the inductance characteristic of the variable inductor of the RF matching unit shown in FIG. 16 .
FIG. 18 illustrates an example of a phase magnitude (PM) sensing board.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be through and complete, and will fully covey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
FIG. 1 shows schematically a general circuit of an equipment using an RF matching unit. The RF matching unit is an apparatus for matching the RF energy of an RF generator 14 to the RF energy of a plasma reaction or process chamber 15 . As shown in FIG. 1, the RF matching unit 1 receives the RF power from the RF generator 14 , and regulates and supplies the RF power to the process chamber 15 . The RF matching unit 1 comprises a variable capacitor 12 , an invariable capacitor 13 , a variable inductor 16 , and a phase magnitude (PM) sensing board 17 . The PM sensing board 17 controls the relative position of two inductors ( 4 , 5 in FIG. 2) of the variable inductor 16 to match the impedance. Also, the RF matching unit 1 further includes a controller (not shown in FIG. 1) for controlling property values of the variable capacitor 12 and the variable inductor 16 , as will be described later.
FIG. 2 is a perspective view of an RF matching unit in accordance with a first embodiment of the present invention. As shown in FIG. 2, the RF matching unit 1 of the present invention comprises a variable capacitor 2 , an invariable capacitor 3 , and a variable inductor 45 . The RF power inputted to the RF matching unit 1 from a RF generator is supplied to a process chamber through an output terminal 8 via the variable capacitor 2 , the variable inductor 45 and the invariable capacitor 3 . The variable capacitor 2 of the RF matching unit 1 contains a plurality of shield blades 6 and a plurality of capacitive plates (not shown) interspersed between each pair of blades 6 . In a conventional manner, increasing or decreasing the area of each capacitive plate that overlaps the blade 6 alters the capacitance of the variable capacitor 2 .
The variable inductor 45 of the RF matching unit 1 has a rotating inductor 4 and a fixed inductor 5 . The fixed inductor 5 of the variable inductor 45 is formed of a conductive pipe 26 having an oval and spiral shaped figure, and a plurality of conducting wires 27 disposed in the conductive pipe 26 , as shown in FIG. 5 . An input end of the conducting wires 27 of the fixed inductor 5 are coupled to an output end of the variable capacitor 2 . Alternatively, the conducting wires 27 can be replaced by one conductive wire having the same diameter as that of the conductive pipe 26 .
The rotating inductor 4 of the variable inductor 45 is also formed of a conductive pipe 26 having an oval and spiral shaped figure, and a plurality of conducting wires 27 disposed in the conductive pipe 26 . The conducting wires 27 of the rotating inductor 4 can be also replaced by one conductive wire having the same diameter as that of the conductive pipe 26 . A rotation angle of the rotating inductor 4 is controlled by means of a controller (not shown) of the RF matching unit. The inner diameter of the fixed inductor 5 is larger than the outer diameter of the rotating inductor 4 . Therefore, the rotating inductor 4 can be inserted into the fixed inductor 5 and rotated in a direction B, as shown in FIG. 2 . The degree of overlap between the two inductors 4 and 5 can be controlled by increasing or decreasing the distance between the rotating axis of the rotating inductor 4 and the center of the fixed inductor 5 .
In order to control the degree of overlap between the two inductors 4 and 5 , the RF matching unit 1 of the present invention further includes a transfer device that moves the rotating inductor 4 in a direction A, i.e., up and down direction as shown in FIG. 2 . The transfer device includes a motor and gear arrangement, for example a rack and pinion for transforming a rotating movement of the motor into a reciprocating movement. Thus, the rotating inductor 4 can be rotated and moved in the directions B and A to control the degree of overlap, so that an inductance value of the variable inductor 45 can be controlled at a greater width.
Alternatively, a transfer device can be configured to move the fixed inductor 5 , instead of moving the rotating inductor 4 . For example, a transfer device that moves the fixed inductor 5 can be formed of a motor/gear structure having a motor disposed on an end of an axis of the fixed inductor 5 and a gear arrangement, i.e., a rack and pinion for transforming a rotating movement of the motor into a reciprocating movement, or a bolt/nut structure having mounting racks for receiving and guiding both ends of an axis of the fixed inductor 5 and bolts and nuts for fixing the both ends of the axis of the fixed inductor 5 at a given position.
FIG. 3 is a perspective view showing a connecting member between components of the RF matching unit 1 shown in FIG. 2 . The connecting member 7 can be used to connect the output end of the variable capacitor 2 with the input end of the fixed inductor 5 , or the output end of the rotating inductor 5 with the input end of the invariable capacitor 3 . The connecting member 7 of the present invention comprises upper and lower grippers 9 , 9 ′ having semi-arc shaped gripping portions, and bolts 10 , 10 ′ and/or nuts (not shown) for fastening the upper and lower grippers 9 , 9 ′, as shown in FIG. 3 . The conductive pipes 26 of the corresponding components are connected to each other by placing welded ends thereof between the gripping portions of the upper and lower grippers 9 , 9 ′ and fastening the upper and lower grippers 9 , 9 ′ with bolts 10 , 10 ′ and/or nuts. Thus, the conductive pipes 26 are connected to each other without being penetrated by locking means such as bolts, so that loss of RF energy is minimized.
FIG. 4 is a perspective view of an ‘E’ shaped ring 11 for fixing coil turns of the rotating and fixed inductors 4 , 5 shown in FIG. 2 and FIG. 5, in a spaced-apart relation with respect to one another. The ‘E’ shaped rings 11 of the RF matching unit 1 are disposed at regular intervals between the coil turns of the conductive pipes 26 forming the rotating and fixed inductors 4 , 5 , as shown in FIG. 2 . Each of the ‘E’ shaped rings 11 are designed to have a minimized capacity so as not to influence the magnetic field generated by the rotating and fixed inductors 4 , 5 . The ‘E’ shaped rings 11 are formed of a non-conductive and heat-resistant material, for example a plastic or ceramic material.
FIG. 6 is an exploded perspective view of a wire connecting portion of the rotating inductor 4 shown in FIG. 2 . The rotating inductor 4 respectively coupled with the input end of the invariable capacitor 3 and with an output end of the fixed inductor 5 , is apt to become broken at connecting portions therebetween since it is rotated continuously within a limit of about 180°. To prevent breaking of the connecting portions, the wire connecting portions formed as shown in FIG. 6 are disposed at both ends of the rotating inductor 4 .
As shown in FIG. 6, the wire connecting portion of the rotating inductor 4 coupled with the input end of the invariable capacitor 3 comprises a mount 25 for mounting one end of the rotating inductor 4 , a stopper 21 for maintaining the one end of the rotating inductor 4 in a given position during the rotation, a rotation supporting section 22 having a plurality of the conducting wires 27 disposed therein, an elastic plate 20 having a contact section 23 for receiving and supporting the rotation supporting section 22 , and an output connecting section (not shown) for connecting the conducting wire 27 with the invariable capacitor 3 by using a connector including wire connecting member 7 . The induced current generated by the rotation of the rotating inductor 4 flows in a direction C to be outputted to the invariable capacitor 3 through the output connecting section connected with the conducting wire 27 . Thus, the conducting wires 27 can perform within the operation limit, i.e., about 180° of the rotating inductor 4 without breaking.
The wire connecting portion of the rotating inductor 4 coupled with the output end of the fixed inductor 5 has the same structure as that of the wire connecting portion of the rotating inductor 4 coupled with the input end of the invariable capacitor 3 , except that it is disposed at the other end thereof and is arranged with an axis of a motor that rotates the rotating inductor 4 .
During operation of the RF matching unit 1 of the present invention to match the input impedance to the load impedance, a controller determines a rotating angle and a vertical position of a rotating inductor 4 according to an electrical signal from the PM sensing board 17 as illustrated in FIG. 1, and generates a control signal to a driving portion, such as a motor that rotates the rotating inductor 4 . At this time, the controller calculates combined inductance between the rotating and fixed inductors 4 , 5 as a nonlinear function of the rotating angle and the vertical position of the rotating inductor 4 . Thus, the rotating inductor 4 is rotated and positioned at the proper place through several feedback processes until the process chamber reaches a stable state.
In more detail, PM sensing board 17 of FIG. 1 controls variable inductor 16 to match the impedance of RF generator 14 with that of process chamber 15 . To this end, the RF matching unit 1 determines as a first condition whether the voltage (V) supplied from RF generator 14 to process chamber 15 is in phase with the current (I) thereto, and as a second condition whether the absolute ratio value of the voltage and the current (i.e., V/I) is a specific value (e.g., 50 Ohms).
FIG. 18 illustrates on example of phase magnitude (PM) sensing board 17 . With regard to the above noted first condition, the RF power (P) from RF Generator 14 can be effectively or maximally transferred to process chamber 15 without any loss when there is no phase difference (θ) between the voltage (V) and the current (I), because the RF power (P) is defined by V*I*cos θ. If the voltage (V) and the current are proportional to the voltage of capacitor C 1 and the current induced by inductor L 1 , respectively, and the phase difference (θ) between the voltage (V) and the current (I) can be detected across variable resistor VR 1 . The resistance of resistor VR 1 is adjusted such that the voltage across the resistor VR 1 is zero when the current (I) and the voltage (V) are in phase with one another.
Accordingly, if the current (I) leads the voltage (V) in phase, then the voltage across resistor VR 1 has a positive (+) value. If the current (I) is in phase with the voltage (V), then the voltage across resistor VR 1 is equal to zero (0). If the current (I) lags the voltage (V) in phase, then the voltage across resistor VR 1 has a negative (−) value. The circuit portion consisting of components C 1 , L 1 , R 1 -R 5 , D 1 , D 2 and VR 1 functions to convert the phase difference into a DC value. Responsive to the voltage across resistor VR 1 , a motor (not shown) is driven in either a clockwise or counter clockwise direction, to control the relative position of inductors 4 and 5 of variable inductor 16 .
With regard to the above noted second condition, RF generator 14 must also satisfy a specific required load value (e.g., 50 Ohms) for impedance matching. The resistance of variable resistor VR 2 is adjusted such that the voltage across resistor VR 2 is zero when the ratio of V/I at the output of RF generator 14 is equal to the required load value (e.g., 50 Ohms).
Accordingly, if the ratio of V/I is greater than the required load value, then the voltage across the resistor VR 2 has a positive (+) value. If the ratio is equal to the required load value, then the voltage across resistor VR 2 is equal to zero (0). If the ratio is less than the required load value, then the voltage across resistor VR 2 has a negative (−) value. The circuit portion consisting of components L 1 , C 2 , D 3 , D 4 , R 7 -R 8 , and VR 2 converts the V/I ratio of RF generator 14 into a DC value. The voltage across resistor VR 2 is used to drive a motor (not shown) in either a clockwise or counter clockwise direction, to control the relative position of electrodes of variable capacitor 12 . The above noted motors (not shown) thus function to control property values of variable inductor 16 and variable capacitor 12 , responsive to PM sensing board 17 .
FIG. 7 shows a different form of the variable inductor 45 of the first embodiment of the present invention shown in FIG. 2 . The variable inductor of the different form comprises a fixed coil 130 , and a rotating coil 133 having a rotating axis. Each of the fixed and rotating coils 130 , 133 are formed of a single spiral and oval shaped conducting wire different from that of the variable inductor 45 shown in FIG. 2 . In this embodiment, the turns of coils 130 and 133 are separated from each other by E-shaped rings or an electrical isolation material coated thereon.
An output end 132 of the fixed coil 130 is coupled electrically with an input end 135 of the rotating coil 133 . An input end 310 of the fixed coil 130 and an output end 134 of the rotating coil 133 are coupled electrically with the output end of the variable capacitor 12 and the input end of the invariable capacitor 13 shown in FIG. 1, respectively. Also, the inner diameter of the fixed coil 130 is larger than the outer diameter of the rotating coil 133 . Therefore, the rotating coil 133 can be rotated at the magnetic flux of the fixed coil 130 , as shown in FIG. 7 . Thus, according to the rotation of the rotating coil 133 , the inductance of the variable inductor is changed.
In order to be disposed within the RF matching unit, the variable inductor shown FIG. 7 can include various means, such as for example a mounting element that fixes the fixed coil 130 on the RF matching unit, a motor that rotates the rotating coil 130 , and a connector that connects an axis of the motor with an axis of the rotating coil 133 . The fixed and rotating coils 130 , 133 generating the induced current can be connected electrically in series or in parallel with each other.
FIG. 8 is a schematic perspective view showing a variable inductor of an RF matching unit in accordance with a second embodiment of the present invention. The variable inductor of the RF matching unit of the second embodiment comprises a band type rectangle and whirl shaped fixed coil 110 , and a band type rectangle and whirl shaped rotating coil 113 having a rotating axis 116 penetrating the fixed coil 110 . The inner diameter of the fixed coil 110 is larger than the outer diameter of the rotating coil 113 so that the rotating coil 113 is disposed in the fixed coil 110 . An output end 112 of the fixed coil 110 is coupled electrically with an input end 114 of the rotating coil 113 , in a manner as illustrated in FIG. 8A for example. An input end 111 of the fixed coil 110 and an output end 115 of the rotating coil 113 are coupled electrically with the output end of the variable capacitor 12 and the input end of the invariable capacitor 13 shown in FIG. 1, respectively.
During operation of the variable inductor, when the power is supplied to the variable inductor, the fixed and rotating coils 110 , 113 generate magnetic fluxes, respectively. At this time, the magnetic flux of the fixed coil 110 is fixed in a given direction, but the magnetic flux of the rotating coil 113 is formed at certain angles with respect to the magnetic flux of the fixed coil 110 , as much as a rotated angle thereof. Therefore, the magnetic fluxes of the fixed and rotating coils 110 , 113 have influence on each other to vary the whole magnetic flux of the variable inductor. Thus, according to the rotated angle of the rotating coil 113 , the whole magnetic flux of the variable inductor is varied.
In order be disposed within to the RF matching unit, the variable inductor of the second embodiment of the present invention also includes various means, such as for example a mounting element that fixes the fixed coil 110 on the RF matching unit, a motor that rotates the rotating coil 113 , and a connector that connects an axis of the motor with the axis 116 of the rotating coil 113 . Also, the fixed and rotating coils 110 , 113 can be connected electrically in series or in parallel with each other.
FIG. 9 is a graph showing the inductance characteristic of the variable inductor of the RF matching unit of second embodiment of the present invention. Referring to FIG. 9, when the fixed and rotating coils 110 , 113 of the variable inductor are respectively positioned at the same angle to respectively generate magnetic flux in the same direction, the whole magnetic flux, i.e., the whole inductance of the variable inductor, becomes a maximum value Lmax. Then, when the rotating coil 113 begins to be rotated in one direction, the whole magnetic flux of the variable inductor is decreased, and thereby the whole inductance of the variable inductor is reduced.
When the rotating coil 113 is rotated and positioned at π/2, the magnetic flux of the rotating coil 113 is crossed at right angles with the magnetic flux of the fixed coil 110 , so that reciprocal influence on the magnetic flux is minimized. At this time, the inductance of the variable inductor is almost the same as a summation of respective inductance native to the fixed and rotating coils 110 , 113 . This case also occurs when the rotating coil 113 is rotated and positioned at 3π/2.
When the rotating coil 113 is positioned at π, the magnetic fluxes of the fixed and rotating coils 110 , 113 are positioned in opposite directions with respect to each other. At this time, the whole inductance of the variable inductor becomes a minimum value Lmin. Thereafter, when the rotating coil 113 is rotated and positioned at 2π, the whole inductance of the variable inductor once again becomes the maximum value Lmax. Thus, according to the rotation of the rotating coil 113 , the whole inductance of the variable inductor is varied.
During operation of an RF matching unit 1 , after articles such as wafers to be processed are put into a process chamber 15 , a controller determines a rotating angle and a vertical position of a rotating inductor according to an electrical signal from a PM sensing board 17 , and generates a control signal to a driving portion such as a motor for rotating the rotating inductor. Thus, the rotating inductor is rotated and positioned at the proper place to match the impedance of an RF generator to the impedance of the process chamber 15 .
FIG. 10 is a schematic perspective view showing a variable inductor of an RF matching unit in accordance with a third embodiment of the present invention. Referring to FIG. 10, the variable inductor of the second embodiment of the RF matching unit comprises a band type rectangle and whirl shaped fixed coil 140 , and a band type rectangle and whirl shaped moving coil 143 . The fixed and moving coils 140 , 143 are arranged to generate magnetic fluxes in the same direction and are positioned to be spaced apart from each other and opposite from each other. The moving coil 140 can be moved horizontally in parallel with respect to the fixed coil 143 , as shown in FIG. 10 . An output end 142 of the fixed coil 140 is coupled electrically with an input end 144 of the moving coil 143 . An input end 141 of the fixed coil 140 and an output end 145 of the moving coil 143 are coupled electrically with the output end of the variable capacitor 12 and the input end of the invariable capacitor 13 shown in FIG. 1, respectively.
During operation, when power is supplied to the variable inductor, the fixed coil 140 and the moving coil 143 respectively generate magnetic flux. At this time, if the moving coil 143 is moved horizontally, the magnetic fluxes of the fixed and moving coils 140 , 143 have influence on each other in proportion to overlapping degree therebetween, to vary the whole magnetic flux. Thus, according to the overlapping degree controlled by moving the moving coil 143 , the whole magnetic flux of the variable inductor is varied and thereby the inductance is also varied.
Alternatively, the fixed and moving coils 140 , 143 can be arranged to generate magnetic fluxes in the opposite direction. Also, the fixed and rotating coils 140 , 143 can be connected electrically in series or in parallel with respect to each other. In order to be disposed within the RF matching unit, the variable inductor of the third embodiment of the present invention also includes various means, such as for example a mounting element that fixes the fixed coil 140 on the RF matching unit, and a moving element including a motor that moves the moving coil 143 .
FIG. 11 is a graph showing the inductance characteristic of the variable inductor of the third embodiment of the present invention. Referring to FIG. 11, in the case that the fixed and moving coils 140 , 143 are disposed to generate the magnetic fluxes in the same direction with respect to each other and are placed opposite each other, the magnetic fluxes of the fixed and moving coils 140 , 143 are completely overlapped. At this time, the whole inductance becomes a maximum value Lmax 1 . When the moving coil 143 is moved horizontally, overlapping area between the fixed and moving coils 140 , 143 is decreased and thereby the inductance of the variable inductor is also reduced. When the moving coil 143 reaches to a distance dth to thereby not have influence on the magnetic fluxes, the whole inductance becomes a minimum value Lmin 1 .
On the contrary, in the case that the fixed and moving coils 140 , 143 are disposed to generate the magnetic fluxes in opposite directions with respect to each other, the more that overlapping area between the fixed and moving coils 140 , 143 is increased, the more the inductance of the variable inductor is reduced. Namely, when the fixed and moving coils 140 , 143 are completely overlapped, the inductance becomes a minimum value Lmin 2 , whereas when the moving coil 143 reaches to the distance dth to thereby not have influence on the magnetic fluxes, the inductance becomes a maximum value Lmax 2 .
FIG. 12 is a perspective view showing a variable inductor of an RF matching unit in accordance with a fourth embodiment of the present invention. Referring to FIG. 12, the variable inductor of the RF matching unit of the second embodiment comprises a circular and spiral shaped fixed coil 160 , and a circular and spiral shaped moving coil 163 . Coil turns of the fixed coil 160 are formed to have winding width enough to be interspersed between each pair of coil turns of the moving coil 163 . The moving coil 163 disposed from the fixed coil 160 upward can be moved up and down to be overlapped with or separated from the fixed coil 160 .
An output end 161 of the fixed coil 160 is coupled electrically with an input end 164 of the moving coil 163 . An input end 162 of the fixed coil 160 and an output end 165 of the moving coil 163 are coupled electrically with the output end of the variable capacitor 12 and the input end of the invariable capacitor 13 shown in FIG. 1, respectively. The fixed and moving coils 160 , 163 are arranged to generate magnetic fluxes in the same direction. Alternatively, the fixed and moving coils 160 , 163 can be disposed to generate magnetic fluxes in opposite directions with respect to each other. Also, the fixed and rotating coils 160 , 163 can be connected electrically in series or in parallel with respect to each other.
During operation, according to overlapping degree between the fixed and moving coils 160 , 163 controlled by moving up or down the moving coil 163 , the whole magnetic flux of the variable inductor is varied and thereby the inductance is also varied. In the variable inductor of the fourth embodiment, the inductance characteristic is similar to that of the variable inductor of the third embodiment of the present invention, shown in FIG. 11 .
In order be disposed within to the RF matching unit, the variable inductor of the fourth embodiment of the present invention also includes various means, such as for example a mounting element that fixes the fixed coil 160 on the RF matching unit, and a moving element including a motor for moving the moving coil 163 .
FIG. 13 is a perspective view showing a variable inductor of an RF matching unit in accordance with a fifth embodiment of the present invention. The variable inductor of the RF matching unit of the fifth embodiment comprises a band type rectangle and whirl shaped fixed coil 170 , and a rectangle shaped magnetic shield rotating plate 173 disposed in the fixed coil 170 . The magnetic shield rotating plate 173 has a rotating axis 174 penetrating the fixed coil 170 . Input and output ends 171 , 172 of the fixed coil 170 are coupled electrically with the output end of the variable capacitor 12 and the input end of the invariable capacitor 13 shown in FIG. 1, respectively.
During operation, when the power is supplied to the variable inductor, the fixed coil 170 generates magnetic flux. At this time, the magnetic flux of the variable inductor is varied according to a rotated angle of the magnetic shield rotating plate 173 , since the magnetic flux of the fixed coil 170 is fixed in a given direction. Thus, the inductance of the variable inductor is varied.
In order be disposed within the RF matching unit, the variable inductor of the fifth embodiment of the present invention can also include various means, such as for example a mounting element that fixes the fixed coil 170 on the RF matching unit, a motor for rotating the magnetic shield rotating plate 173 , and a connector that connects an axis of the motor with the axis 174 of the magnetic shield rotating plate 173 .
FIG. 14 is a graph showing the inductance characteristic of the variable inductor of the fifth embodiment of the present invention. Referring to FIG. 14, when the magnetic shield rotating plate 173 is positioned to be crossed at right angles to the magnetic flux of the fixed coil 170 at first, most of the magnetic flux of the fixed coil 170 is shielded and thereby the magnetic flux, i.e., the inductance of the variable inductor, becomes a minimum value Lmin. Then, when the magnetic shield plate 173 begins to be rotated in one direction, shielding extent of the magnetic flux is decreased and thereby the inductance of the variable inductor is increased.
When the magnetic shield plate 173 is rotated and positioned at δ/2, the magnetic shield plate 173 is crossed at right angles with the fixed coil 170 and the shielding extent of the magnetic flux is minimized. At this time, the inductance of the variable inductor becomes a maximum value Lmax. This case also occurs when the magnetic shield plate 173 is rotated and positioned at 3π/2.
When the magnetic shield plate 173 is positioned at π, the shielding extent of the magnetic flux is maximized. At this time, the whole inductance of the variable inductor becomes a minimum value Lmin. Thereafter, when the magnetic shield plate 113 is rotated and positioned at 2π, the inductance of the variable inductor once again becomes the minimum value Lmin as that at first. Thus, according to the rotation of the magnetic shield plate 173 , the inductance of the variable inductor is varied.
FIG. 15 is a perspective view showing a variable inductor of an RF matching unit in accordance with a sixth embodiment of the present invention. The variable inductor of the RF matching unit of the sixth embodiment comprises a circular and spiral shaped fixed coil 190 , and a circular shaped magnetic shield rotating plate 193 . The magnetic shield rotating plate 193 disposed rotatably at the magnetic flux of the fixed coil 190 has rotating axes 194 , 195 formed on both sides thereof. Input and output ends 191 , 192 of the fixed coil 190 are coupled electrically with the output end of the variable capacitor 12 and the input end of the invariable capacitor 13 shown in FIG. 1, respectively.
During operation, when the power is supplied to the variable inductor, the fixed coil 190 generates magnetic flux. At this time, the magnetic flux of the variable inductor is varied according to a rotated angle of the magnetic shield rotating plate 193 , since the magnetic flux of the fixed coil 190 is fixed in a given direction. Thus, the inductance of the variable inductor is varied. In the variable inductor of the sixth embodiment, the inductance characteristic is similar to that of the variable inductor of the fifth embodiment of the present invention shown in FIG. 14 .
In order be disposed within the RF matching unit, the variable inductor of the sixth embodiment of the present invention can also include various means, such as for example a mounting element that fixes the fixed coil 190 on the RF matching unit, a motor for rotating the magnetic shielding rotating plate 193 , and a connector that connects an axis of the motor with the axes 194 , 195 of the magnetic shield rotating plate 193 .
FIG. 16 is a perspective view showing a variable inductor of an RF matching unit in accordance with a seventh embodiment of the present invention. The variable inductor of the RF matching unit of the seventh embodiment comprises a circular and spiral shaped variable coil 1100 , a mounting plate 1130 for mounting the variable coil 1100 , and a moving bar 1140 for adjusting the length of the variable coil 1100 . The moving bar 1140 is fixed to one end 1110 of the variable coil 1100 through the center of the mounting plate 1130 and the variable coil 1100 . The other end 1120 of the variable coil 1100 is fixed to the mounting plate 1130 . Both ends 1110 , 1120 of the variable coil 1100 are coupled electrically with the output of the variable capacitor 12 and the input end of the invariable capacitor 13 shown in FIG. 1, respectively.
During operation, as the moving bar 1140 is moved forward or rearward within the limit of the distance d, the length of the variable coil 1100 is increased or decreased and thereby the magnetic flux, i.e., the inductance of the variable inductor is varied.
FIG. 17 is a graph showing the inductance characteristic of the variable inductor of the seventh embodiment of the present invention. Referring to FIG. 17, when the length of the variable coil 1100 is minimized, the inductance becomes a maximum value Lmax, and when the length of the variable coil 1100 is maximized, the inductance becomes a minimum value Lmin.
In order be disposed within the RF matching unit, the variable inductor of the seventh embodiment of the present invention can also include various means, such as for example a motor for moving the moving bar 1140 , and a connector that connects an axis of the motor with the moving bar 1140 .
As apparent from the foregoing description, it can be appreciated that the present invention provides a RF matching unit that can vary the magnetic flux, i.e., the inductance by changing the relative position, for example the relative angle or the relative distance between two coils, or between a coil and a magnetic shield plate forming a variable inductor. Also, the present invention can vary the magnetic flux by changing a length of a magnetic coil with a given number of coil turns, thereby forming a variable inductor.
Also, it is noted that a variable inductor of the present invention can be applied to various RF matching networks for matching impedance of a RF source to the impedance of various RF loads, such as for example etching equipment, sputtering equipment, plasma equipment for surface treatment, and a plasma scrubber for removing contaminants in which corresponding semiconductor fabrication processes are performed on articles such as semiconductor wafers or modules, thereby to perform the processes under more stable conditions.
Also, the present invention facilitates variable control and adapts to use in high frequency and high power applications, since the inductance is controlled by magnetic shielding or overlapping of magnetic fluxes.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
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An apparatus for matching the impedance of an RF generator to the impedance of an RF load, for use in manufacturing semiconductor devices by using a plasma. The apparatus includes a variable inductor coupled to a variable capacitor and an invariable capacitor, the variable inductor having two inductors coupled electrically with each other in series and disposed adjacent to each other. At least one of the two inductors is disposed movably to make the magnetic flux of the one inductor interfere with the magnetic flux of the other inductor, thereby to control the inductance of the variable inductor. In the case of a plasma enhanced semiconductor wafer processing system, the apparatus can reduce the time necessary to achieve an RF match between the RF generator and the RF load, thereby increasing the life of the apparatus.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is the US National Stage of International Application No. PCT/EP2007/052518 filed Mar. 16, 2007, and claims the benefit thereof. The International Application claims the benefits of German application No. 10 2006 022 595.3 DE filed May 15, 2006. Both of the applications are incorporated by reference herein in their entirety.
FIELD OF INVENTION
The present application relates to a method for checking the transmission backlash in an arrangement (such as a production machine, for example a machine tool) in which a motor moves a load via a transmission, a transducer being arranged on a drive element of the motor. It also relates to a production machine, in particular machine tool, with a motor which includes a drive element on which a transducer determines an angular position or translatory position of the drive element and/or a value derived therefrom, and with a transmission by means of which the motor transmits a force to a load.
BACKGROUND OF INVENTION
A toothed belt may be used as the transmission; however, the transmission may also include gear wheels. Usually, the transmission backlash increases constantly as a result of wear when the arrangement (production machine) is operated. If the transmission backlash becomes excessive, the operation of the machine is impaired. In the prior art the transmission backlash is monitored by the provision of purpose-made sensors. In this case, in addition to the transducer on the drive element, a second transducer (e.g. shaft encoder) is provided which determines the angular position or the position of the load downstream of the transmission. The transmission backlash is then measured directly by subtraction between the two transducers. As a rule, a second transducer is expensive.
In most cases the transmission backlash is monitored by manual checking at regular test intervals using measuring instruments. In the case of toothed belts the belt tension is measured, for example, acoustically. If the tension becomes too low and the transmission backlash therefore too large, the toothed belt is exchanged. The use of additional sensors is complex and costly. In comparison to manual monitoring of the transmission backlash, it must be ensured, in particular, firstly that excessive transmission backlash is detected reliably, and secondly that maintenance does not have to take place too early. The objective is therefore to find an optimum time for maintenance, and preferably for exchanging transmission parts.
EP 1 489 401 A1 describes a method for determining the amount of wear in a drive arrangement comprising, for example, a gear rack and a pinion. A base torque and a harmonic thereof are applied to the arrangement and a response signal, in particular the angular velocity or angular offset as a function of time, is measured by a transducer (sensor) present in the arrangement in any case. The response signal is analyzed, for example using discrete fast Fourier transformation. The response signal can be compared to a corresponding response signal which was obtained under ideal running conditions of the arrangement.
The selected harmonic of the torque is selected explicitly such that the frequency is lower than 90% of the lowest natural frequency in the arrangement. An optimum evaluation result is claimed to be obtained thereby.
SUMMARY OF INVENTION
It is an object of the invention to provide a method for checking transmission backlash which is especially efficient. A production machine of the type mentioned is to be developed correspondingly.
The object is achieved by a method with the features according to the independent claim.
The method comprises the steps:
a) application of a test control signal, which includes two periodic signals with two defined frequencies, to the motor in a base state of the arrangement (the base state preferably corresponds to a state of minimum transmission backlash at the start of operation of the machine, for example after adjustment of the transmission; the test control signal may have substantially practically any desired form, provided it contains the two periodic signals), b) measurement with the transducer of a measurement value, for example the angular position or a translatory position of the drive element (depending on whether a rotation or translatory motion of the drive element is concerned), and/or of the first and/or of the second derivative of the position, in response to the test control signal, c) determination of the ratio of the amplitudes for the two defined frequencies from the measurement value, d) application of a test control signal (which again may have practically any desired form) to the motor at a test time after operation of the arrangement since carrying out step a) (that is, when wear and therefore a large amount of transmission backlash are to be expected), e) measurement with the transducer of a measurement value, for example the angular position or a translatory position of the drive element and/or of the first and/or of the second derivative of the position, in response to the test control signal, f) determination of the ratio of the amplitudes for the two defined frequencies, g) comparison of the ratios obtained in steps c) and f) with one another or with a threshold value, and determination, on the basis of a predefined criterion, of whether the transmission backlash at the test time deviates from the transmission backlash in the base state to such an extent that maintenance is required.
The method is based on recognition of the fact that transmission backlash affects the motion of the drive element. The forces/moments of the motor, for example magnetic forces and the external forces of the load which react on the drive element through the transmission, act on the drive element. The motion of the drive element therefore results from the sum of all the forces. In certain frequency ranges, the forces of the load react on the drive element in such a manner that the motion of the drive element is heavily damped. In this case the load, in conjunction with the transmission, acts as an absorber. The absorption becomes smaller the greater the transmission backlash becomes. If the type of analysis, for example the two frequencies, is suitably selected, there are, at these frequencies, large differences in amplitudes and phases of the Fourier components in the actual signal, in relation to a predefined reference signal (predefined by the test control signal). A numerical value for the transmission backlash does not need to be determined; rather, it needs only to be determined whether the transmission backlash influences the reaction of the drive element on the transmission, i.e. the absorption, to such an extent that maintenance of the transmission is required. For this reason, various types of test control signal are possible, and there are also a large number of possibilities in determining measurement values and in deriving further values from these measurement values.
Steps a) to g) may be carried out while interrupting the process or may accompany the process.
A test signal which includes two periodic signals with two defined frequencies is used as the test signal, the ratio of the amplitudes is determined as another value, and these ratios can then be compared to one another in step g). Preferably, however, the ratio determined at the test time is compared to a threshold value. If the two frequencies are selected such that an amplitude increase occurs at the one frequency and an amplitude decrease occurs at the other frequency, with increasing transmission backlash, this effect increases mathematically as a ratio value is formed, and thereby becomes clearer.
The test control signal may also contain a multiplicity of Fourier components for frequency portions between a lower and an upper frequency, i.e. a complete frequency band. Accordingly, in steps c) and f) amplitude and phase for a whole multiplicity of frequencies can be determined. Measurement curves are then obtained, and in step g) a curve evaluation can be carried out. For example, it can be established from the curve where the so-called absorber frequency is located, that is, at which frequency the absorption is strongest. The invention, in which two frequencies were selected, implies that the location of the absorber frequency is approximately known. By contrast, the embodiment now mentioned, in which the frequency band is used at the outset, helps in seeking the absorber frequency.
The test control signal may also be a noise signal. In other words, the time curve of the test control signal does not need to be defined.
A production machine (where in the present case a machine tool may also fall under the concept of a production machine) or robot is characterized by the fact that the motor can adopt an operating state and a test state. (These states might also be defined with reference to a motor control system and not to the motor itself.) In the test state the motor receives and processes test control signals. Also in the test state, an evaluation unit evaluates measurement signals of the transducer as a function of the test control signals.
Therefore, the motor is not operated (or switched off) continuously, but is tested automatically in operating pauses or in parallel to the process.
The motor is preferably designed to adopt the test state for monitoring the transmission slack at regular time intervals. In the test state the evaluation unit then determines in each case, on the basis of a predefined criterion, whether maintenance of the transmission is required. In the event that maintenance is required, it emits a warning signal.
By virtue of this embodiment, intervention by an operator is no longer required. The motor control system automatically initiates the test state. Because this type of testing is considerably simpler than if a human operator had to carry out the test manually, the test can take place considerably more often. It is thereby avoided that maintenance takes place too frequently or, conversely, too late.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are described below with reference to the drawing, in which:
FIG. 1 shows schematically the basic structure of an arrangement in which the invention is used;
FIG. 2 shows a physical model of the basic structure;
FIGS. 3A to 3C show frequency responses of amplitude and phase in an arrangement according to FIG. 1 or FIG. 2 which were recorded in connection with the invention;
FIG. 4A shows a test control signal such as may be used in the invention, and
FIGS. 4B and 4C show response signals to the test control signal for two different situations.
DETAILED DESCRIPTION OF INVENTION
An arrangement comprises a motor (drive) with a drive element 10 (e.g. a motor shaft) on which a transducer 12 measures the position of the drive element. In the example shown, this is a rotational position, that is, the angular position of the drive element 10 , so that the transducer 12 may be an incremental shaft encoder. The drive element 10 exerts a force on a load 14 via a transmission 13 , which may be a toothed belt or may include gear wheels. If the arrangement in FIG. 1 is a production machine the load is, for example, a sealer jaw, a ball screw drive or a robot arm.
In physical terms, a model as shown in FIG. 2 can be produced. The drive element 10 has a mass m antr . The force F antr (in the case of translatory motion), or a torque M antr (in the case of rotary motion), acts on this mass. The mass m antr changes its position x antr , where x antr denotes either a translatory position or an angle. (Correctly formulated, in the rotary case a mass moment of inertia J is defined instead of the mass.)
The load has a mass m Last on which the forces F prozess (process force) and friction F reib act. In the case of a rotary motion, a corresponding torque acts. Regardless of whether a translatory or a rotary motion is concerned, the change of position of the load 14 is described by means of the position value x Last .
The masses m antr of the drive element 10 and m Last of the load 14 are, of course, connected to one another via the transmission, which exerts, firstly, a spring force with the spring constant k and, secondly, a damping effect with the damping constant d.
The transmission 13 therefore has the effect that the value F antr and M antr is not transmitted directly to the load. Rather, oscillation processes take place in the transmission, for example in the toothed belt 13 , as a result of the spring constant k, which oscillation processes are damped with the damping constant d. This system represents (in relation to the motor shaft) an absorber. In this case, the motion of the load 14 acts on the drive element 10 by means of the transmission 13 in such a manner that the drive element 10 does not directly follow its drive force F antr or its drive moment M antr . Therefore, x antr deviates in its actual behavior from its reference behavior.
In FIGS. 3A to 3C , measurements of frequency behavior are shown for three different settings of the transmission backlash. The measuring structure used for this purpose need not be explained in detail. It is sufficient to note that the measuring structure enabled the transmission backlash to be varied by means of a screw. The millimeter figures specified in FIGS. 3A to 3C refer to a position of the screw. For interpretation, it is sufficient that FIG. 3A shows the state in which practically no transmission backlash is present, FIG. 3B shows the state with medium transmission backlash and FIG. 3C shows the state with relatively large transmission backlash.
A rotary system was used. The amplitude-frequency responses (in each case the upper curves in FIGS. 3A to 3C ) show, in logarithmic representation, the ratio of the rotational speed actual value of the drive 10 to the torque reference value (which is substantially proportional to acceleration) acting on the drive element 10 .
For the present purposes it is sufficient to understand that an actual value is compared to a reference value. The absorption is reflected in the actual values; more precisely, the absorption causes a major reduction in the resulting actual value of the rotational speed of the drive in relation to the torque reference value, in a frequency range in the vicinity of the absorber frequency, which results in a downwardly oriented peak in the upper curves in FIGS. 3A to 3C . The respective phases are shown below the amplitude-frequency responses in FIGS. 3A to 3C . In the region of absorption of the frequency, the phase rises from −90° to +90°.
The absorber frequency can therefore be derived from amplitude-frequency responses and phase curves of the kind shown in FIGS. 3A to 3C , as a function of the adjustment travel of the screw, which is a measure for the transmission backlash.
Adjustment travel [mm]
Absorber frequency [Hz]
0.0
103
0.5
102
0.67
101
0.84
90
0.92
73
1.0
60
In Table 1, the absorber frequency determined is shown as a function of adjustment travel.
As can be readily seen from the table, the absorber frequency varies only slightly at the start. With an adjustment travel above 0.67, the absorber frequency decreases rapidly.
In principle, sufficient information can be derived from curves of the type shown in FIGS. 3A to 3C , and from both the amplitude-frequency response and the phase curve, to determine whether the transmission backlash is too great. From the sharp drop in the absorber frequency in the range between 0.67 and 0.84 in Table 1, it can be deduced that a rapid deterioration of the drive occurs precisely between these values of the adjustment travel, and that the transmission must be exchanged or adjusted. (Of course, with the use of the measurement structure not explained in detail here this does not apply, since the transmission backlash is generated artificially. With real systems, it can be recognized clearly from the change in the absorber frequency that the transmission backlash is becoming excessive.)
In principle, it is not necessary to analyze a whole spectrum, as is done for FIGS. 3A to 3C .
Rather, it is possible to select a particular frequency for excitation of the system in a tailored manner. FIG. 4A shows a test control signal which is applied to the drive element 10 and which is purely periodic, with an excitation frequency f anreg and therefore with a period T anreg =1/f anreg . The absorber frequency of the system with a tensioned toothed belt with little transmission backlash was selected for f anreg .
In the event that the toothed belt 13 is tensioned and the transmission backlash is small, the curve shown in FIG. 4B is obtained when measuring the value x antr by means of the transducer 12 . The response signal is naturally also periodic, with the same period T anreg , and has a low amplitude in relative terms.
If a large amount of transmission backlash is present, i.e. the toothed belt 13 is loose, a curve as shown in FIG. 4C is obtained when measuring x antr with the transducer 12 . (In this case the same scales are assumed for the y-axis in comparison to FIG. 4B , although in the present case they are represented in arbitrary units.)
The amplitude of the Fourier component f anreg is therefore increased if a large amount of transmission backlash is present, as compared to the case when little transmission backlash is present. This amplitude alone is therefore sufficient as a criterion for determining whether or not the transmission backlash is excessive.
As a rule, a ratio value between the amplitude of oscillation for the curve in FIG. 4C in comparison to FIG. 4B will be formed. If this value exceeds a threshold value (which is to be defined as a function of the position f anreg in relation to the absorber frequency in the base state), it can be determined by means of a threshold criterion when maintenance should take place and when it should not.
The example explained with reference to FIGS. 4A to 4C applies only to a given frequency. There are also frequencies at which the amplitude decreases with an increase of transmission backlash. In those cases, too, ratio values can be defined and threshold criteria applied.
The case represented in FIGS. 4A to 4C relates to an excitation frequency f anreg which is lower than that the absorber frequency. The opposite case therefore applies when the frequency f anreg is higher than the absorber frequency.
Thus, the following values can, for example, be obtained: in a measurement with the test frequency 80 Hz, the amplitude 100 (arbitrary unit) is obtained with a tensioned toothed belt and the amplitude 80 with a loosened toothed belt. With a test frequency of 110 Hz the amplitude 200 is obtained with a tensioned toothed belt and the amplitude 240 with a loosened toothed belt. Because the amplitude is lowered by loosening the toothed belt at the frequency of 80 Hz, and the amplitude is increased by loosening the toothed belt at the frequency of 110 Hz, the amplitude ratio, for example the amplitude at 80 Hz in comparison to the amplitude at 110 Hz, can be defined. With the above-mentioned exemplary values, the amplitude ratio with a tensioned toothed belt is therefore 0.5, and with a loosened toothed belt 0.33. The change is therefore reflected more strongly in the numerical value than in the individual values, so that the amplitude ratio is an especially suitable value, which is therefore used in the invention claimed.
The test control signal does not necessarily contain only two frequency components. Rather, it is also possible to subject the motor or the drive element 10 to noise signals. Although analysis of the measurement values obtained by the transducer 12 is not quite so simple in this case, curves of the type shown in FIGS. 3A to 3C can nevertheless be derived.
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To determine the backlash in an arrangement in which a motor moves a load via a transmission mechanism, a transducer is used which is present anyway in conventional production machines and which measures an angular position or translatory position of the drive element or a derivative of this quantity. Via the transducer the effect of the backlash on the actual position of the drive element is measured, the actual position being different from the desired position, which is defined by the forces or torques acting on the drive. On the basis of a frequency analysis, quantities can be derived which permit the use of threshold criteria. For example, the drive is driven with a periodic signal which is close to the absorber frequency, i.e. a frequency at which the absorption by the transmission mechanism is greatest.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No. 08/036,149, filed on Mar. 24, 1993, now U.S. Pat. No. 5,441,240.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fence panel assembly and fence that do not permit a line of vision from one side of the panels between the panels to the other side of the panels while still providing ventilation channels between the panels for resistance to high wind.
2. Description of the Prior Art
A variety of fence devices have been used to provide the fence owner with protection and privacy. Prior art fence devices have consisted of fence posts, vertical panels, and horizontal mounting members.
Prior art fences are typically assembled with mechanical fasteners such as bolts, nuts, screws, nails or slipnotch fasteners. The use of multiple mechanical attachments, such as those disclosed in U.S. Pat. Nos. 4,324,388; 3,993,289; 4,471,947; 4,809,955; and 4,202,532, results in time consuming assembly.
Prior art fences typically are open fences such as those disclosed in U.S. Pat. Nos. 4,202,532; 4,809,955; 4,324,388; and 3,993,289. These fences do not provide privacy to the fence owner. The spaces that exist between conventional fence panels often increase in size over time as a result of warping, aging, shrinking, or rotting of the panels. Prolonged exposure of the fence panels to adverse environmental conditions such as sunlight, rain, and wind can weaken the structural integrity of the fence. A closed fence design, such as that disclosed in U.S. Pat. No. 4,471,947, does not provide ventilation for wind or rain forces. Such a design is more likely to be blown over in a high wind than a fence with spaces between panels.
Many prior art fence panels are composed of wood, metal, or plastic resins. These materials require periodic maintenance and are difficult to assemble.
Prior art fence devices fail to solve the problem of providing privacy by not permitting a line of vision between the fence panels and providing resistance to high winds by providing ventilation channels between the fence panels.
The present invention overcomes the problems of the prior art by requiring minimal use of mechanical fasteners and easy assembly of the fence, and providing ventilation channels between fence panels while not permitting a line of vision between adjacent panels. The present invention is uniquely designed to allow the fence panels to successively slide onto two horizontal stringers. The fence panel edges are designed to overlap the edges of adjoining fence panel to form a closed fence with ventilation air channels. This provides the fence owner with privacy and a weather resistant fence. The fence panels and stringers of the present invention are made of a vinyl material. This material is light and requires little to no maintenance.
SUMMARY OF THE INVENTION
The present invention relates to a fence panel assembly and a fence that do not permit a line of vision through the fence or the fence panel assembly. The fence panels are uniquely designed to form angulated ventilation channels that resist rain and wind abuse.
Fence posts are driven into the ground to provide a mounting assembly for the placement of the stringers. The required number and height of the fence posts will vary with the individual fence owner's needs. Two substantially parallel horizontal mounting members, such as stringers, are secured in a substantially horizontal orientation to the fence posts by mechanical fasteners such as bolts and nuts. The stringers run the full length of the fence and comprise upper and lower lobed wings that engage the fence panels.
The fence panels are arranged in a substantially perpendicular orientation to the stringers. A plurality of fence panels, each with upper and lower mounting channels, slidably engage the lobed wings of the two stringers. Each panel comprises a front channel border and a rear channel border extending outwardly from opposite sides of the central body region of the panel. At least one spacer member slidably engages the rear channel border in a substantially perpendicular configuration to each fence panel. The spacer member is attached to ensure maintenance of a uniform distance between the adjacent fence panels and may be of various sizes to accommodate the desired distance between panels. The overlap of these borders forms angulated channels for ventilation. As used herein, the term "angulated channel" means a channel comprising a bend or an angle of sufficient magnitude such that an air current entering one end of the channel must change direction in order to exit the other end of the channel, as shown in FIG. 3. Line of sight vision from one side of the fence, between the panels, to the other side is not permitted by the overlap of the front channel border with the rear channel border of adjoining fence panels.
The angulated channels permit a flow of air between the two adjacent fence panels, which enhances the structural integrity of the fence during adverse environmental conditions such as rain and high winds.
Arch panel members connect the fence panel assemblies at substantially right angles. The use of the arch panel members permits a combination of four fence panel assemblies to enclose a substantially rectangular area. Two extension arms extend outward from the arch panel member. The extension arms are attached to fence panels located at one end of each fence panel assembly. The stringers are secured to fence posts by mechanical fasteners.
The fence panels and fence posts may be equipped with a plurality of caps. The cap slidably fits over the top of the panel or post.
The fence posts may be of a galvanized metal and the stringers, fence panels, arch panel members, spacer and caps may be made of a vinyl material. The fence and fence panel assembly design of the present invention may be easily assembled.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of the invention.
FIG. 2 is a side view of the invention.
FIG. 3 is a top view of the invention.
FIG. 4 is an isometric view of the invention.
FIG. 5 is an isometric view of the fence post and panel caps.
FIG. 6 is an end view of the spacer member.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIGS. 1 and 2, the fence embodiment of the present invention comprises two stringers 1 in a substantially parallel arrangement, each of said stringers comprising a mounting assembly 7 capable of securing the stringer to a fence post 5. The fence embodiment further comprises a plurality of fence panels 3 slidably mounted on the stringers in a substantially parallel arrangement. Each of the fence panels is mounted in a substantially perpendicular configuration to the stringers. The fence panels further comprise angulated channels 25 capable of permitting air flow between the fence panels such that the fence panels are capable of being spaced apart with respect to each other so as not to permit a line of vision from one side of the fence panels between the fence panels to the other side of the fence panels while permitting air flow through the angulated channels, as shown in FIGS. 3 and 4.
In a preferred embodiment, the stringers comprise an upper lobed wing 9 and a lower lobed wing 11. The fence panels comprise an upper mounting channel 13 and a lower mounting channel 14, capable of slidably engaging the upper lobed wing and lower lobed wing, respectively, of the stringers. The upper lobed wing and lower lobed wing of the stringer extend substantially the length of the stringer.
In a preferred embodiment, as shown in FIG. 3, the panels comprise a central body region 19 comprising a first side 20 and a second side 22. A rear channel border 21 extends outward from the first side of the central body region and a front channel border 23 extends outward from the second side of the central body region. The spacer member 24, as shown in FIGS. 3 and 6, is capable of maintaining uniform distance between adjacent fence panels. The spacer member slidably engages the rear channel border as shown in FIG. 3. The angulated channel 25 is formed by the overlap of the front channel border of one panel with the rear channel border of an adjacent panel. The angulated channel extends the length of the fence panel, as shown in FIG. 4. As used herein, the term "front side of the panels" is that side of the fence panels depicted in FIG. 4. As used herein, the term "rear side of the panels" is that side of the fence panels opposite to the front side of the panels. As shown in FIGS. 3 and 4, the angulated channels permit air flow from the front side of the panels, between the panels, to the rear side of the panels.
In another preferred embodiment, as shown in FIG. 4, the present invention is a fence comprising a first pair of stringers in a substantially parallel arrangement, where each end of the stringers is mounted to a fence post 5. The respective ends of the stringers are referred to as the first end 2 and the second end 4. A plurality of fence panels are slidably mounted on the first pair of stringers in a substantially parallel arrangement extending from the first end to the second end of the stringers. Each of the panels is mounted in a substantially perpendicular configuration to the first pair of stringers. Each panel comprises substantially angulated channels capable of permitting air flow between the fence panels. The panels are capable of being spaced apart with respect to each other so as not to permit a line of vision from one side of the panels between the panels to the other side of the panel while permitting air flow through the angulated channel.
This preferred embodiment of the invention further comprises a plurality of fence post caps 26 and fence panel caps 28, as shown in FIG. 5, where the caps are slidably mounted on the top surface of the posts and panels.
This preferred embodiment of the invention further comprises a second pair of stringers in a substantially parallel arrangement, where each end of the stringers is mounted to a fence post 5. The respective ends of this second pair of stringers are referred to as first ends and second ends. A second plurality of fence panels is slidably mounted on the second pair of stringers in the same manner that the first plurality of fence panels is mounted on the first pair of stringers. This embodiment of the invention further comprises an arch panel member 15 comprising two extension arms 17 extending outward from the arch panel member in a substantially perpendicular arrangement to each other. The first extension member is attached to a panel at one end of the first pair of stringers and the second extension member is attached to a panel at one end of the second pair of stringers such that the first pair and second pair of stringers are arranged at a substantially right angle, as shown in FIGS. 3 and 4.
In another preferred embodiment of the present invention, the stringers are mounted to the fence posts by a mechanical fastener, such as a nut and bolt assembly 7, as shown in FIG. 3. In a preferred embodiment, the fence panels are made of vinyl material.
Another preferred embodiment of the present invention is a fence panel assembly comprising two fence panels capable of being slidably mounted adjacent each other in a substantially parallel arrangement on two horizontal mounting members, such as stringers, as shown in FIG. 1. The fence panel assembly comprises substantially angulated channels capable of permitting air flow between the fence panels. The panels are capable of being spaced apart with respect to each other so as not to permit a line of vision from one side of the panels between the panels to the other side of the panels while permitting air flow through the angulated channels. In a preferred embodiment, the fence panels comprise an upper mounting channel and a lower mounting channel capable of slidably engaging each horizontal mounting member.
Many modifications and variations may be made in the embodiments described herein and depicted in the accompanying drawings without departing from the concept of the present invention. Accordingly, it is clearly understood that the embodiments described and illustrated herein are illustrative only and are not intended as a limitation upon the scope of the present invention.
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The present invention relates to a fence panel assembly and fence that do not permit a line of vision from one side of the panels between the panels to the other side of the panels while still providing ventilation channels between the panels for resistance to high wind.
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RELATED APPLICATIONS
The present application claims priority to Japanese Application Number 2014-002014, filed Jan. 8, 2014, the disclosure of which is hereby incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a tool changer with cover means configured to prevent foreign matter from getting into a turret.
Description of the Related Art
Tool changers are conventionally used to automatically change tools to be mounted on the spindle of a machine tool. A plurality of necessary work tools are previously set on this tool changer so that a tool specified for replacement in accordance with the machining state can be automatically mounted on the spindle of the machine tool.
Japanese Patent Applications Laid-Open Nos. 2010-99766, 5-38651, 6-739 and 2006-123116, Japanese Patent No. 3990441, etc., each disclose an example in which a machine tool is fitted with one such automatic tool changer for automatically changing tools. This tool changer comprises a turret with a plurality of grips for gripping the tools.
Conventionally, a turret is provided with cover means that prevents chips and cutting fluid from getting into the turret during workpiece machining. FIG. 11 shows an example of a conventional technique in which a tool changer comprising the turret with the cover means is attached to a machine tool.
In FIG. 11 , a tool (not shown) is mounted on the distal end portion of a spindle 2 of a machine tool 1 . Further, a Z-axis motor 3 is connected to the spindle 2 by a Z-axis ball screw so that the spindle 2 can be driven vertically by the Z-axis motor 3 . Furthermore, the tool changer is provided with a turret 6 for use as a member for changing the tool.
The spindle 2 is provided with a turret cam 4 and a cam follower 5 , whereby the angle of the turret 6 can be changed. The turret 6 comprises a turret mechanism portion 604 and a turret-inside mechanism portion 606 , whereby the turret 6 can be rotated.
Further, a front cover 601 and a rear cover 602 are provided on the front and rear sides, respectively, of the turret 6 , in order to prevent chips and cutting fluid from getting into the turret-inside mechanism portion 606 and adversely affecting it. The rear cover 602 comprises a truncated-cone portion 605 and an outer rear surface portion 603 behind it.
Since the turret cam 4 is provided on the spindle 2 in this tool changer, the turret 6 is subjected to a swinging motion by the cam follower 5 that follows the turret cam 4 as the Z-axis motor 3 is driven to move the spindle 2 vertically.
In the conventional automatic tool changers disclosed in the patent documents described above, the turret is fitted with a plurality of tools and is indexed to change a tool mounted on the spindle, so that the tool change can be performed rapidly and accurately. Since the front side of the turret and a turret base are only connected by simply providing a gap between them, the cutting fluid and chips produced during machining may possibly get into various parts of the turret and adversely affect them.
According to the conventional technique shown in FIG. 11 , moreover, chips produced as a workpiece is machined and cutting fluid used in the machining may sometimes drop along the outer rear surface portion 603 of the rear cover 602 and get into the turret mechanism portion 604 . When the turret 6 is swung, furthermore, the chips and cutting fluid collected on an upper part of the truncated-cone portion 605 of the rear cover 602 may get into the turret mechanism portion 604 in the same way.
Thus, in some cases, the rear cover of the conventional technique may not be able to fully prevent the chips and cutting fluid from getting into the turret mechanism portion 604 .
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a tool changer attached to a machine tool and comprising cover means configured to prevent chips and cutting fluid from getting into a turret mechanism portion.
A tool changer according to the present invention comprises a turret with a plurality of grips for holding tools such that the turret is turned to index a desired tool to change the tools. The tool changer comprises a front cover which covers a front surface of the turret, a rear cover which comprises an outer rear surface portion and covers a rear surface of the turret, a drive source for turning the turret, and a turret mechanism portion configured to transmit a force from the drive source, thereby turning the turret. The outer rear surface portion of the rear cover is formed with a projection and/or a recess which defines a flow passage on an upper side of, or on a left and right sides of, the turret mechanism portion.
According to the tool changer of the present invention, the rear cover of the turret is provided with the projection and/or the recess which defines the flow passage, so that chips and cutting fluid adhering to the rear cover of the turret become liable to drop along the flow passage and can be prevented from flowing on the outer rear surface of the rear cover and getting into the turret mechanism portion.
In a machine tool of the type in which the turret is swung during tool change, even when chips produced as a workpiece is machined and used cutting fluid are collected on the upper side of the rear cover, they are guided along the passage by the swinging motion during the tool change. Thus, the chips and cutting fluid can be kept from getting into the turret mechanism portion.
The passage may be shaped so as to outwardly extend left and right from a transversely central portion of the rear cover as viewed from the front.
Since the passage is shaped so as to outwardly extend left and right from the transversely central portion of the rear cover as viewed from the front, according to this aspect, chips and cutting fluid flow outward as they drop along the passage. Thus, the chips and cutting fluid can be more effectively prevented from getting into the turret mechanism portion.
The cross-sectional shape of the projection or recess may be semicircular, triangular, or square.
According to the present invention, there can be provided a tool changer attached to a machine tool and comprising cover means configured to prevent chips and cutting fluid from getting into a turret mechanism portion.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects and features of the present invention will be obvious from the ensuing description of embodiments with reference to the accompanying drawings, in which:
FIG. 1 is a schematic view showing an example of a rear cover constituting a turret of a first embodiment of a tool changer according to the present invention;
FIG. 2 is a schematic view showing a first modification of the rear cover shown in FIG. 1 ;
FIG. 3 is a schematic view showing a second modification of the rear cover shown in FIG. 1 ;
FIG. 4 is a schematic view showing a third modification of the rear cover shown in FIG. 1 ;
FIG. 5 is a schematic view showing a fourth modification of the rear cover shown in FIG. 1 ;
FIG. 6 is a schematic view showing a fifth modification of the rear cover shown in FIG. 1 ;
FIGS. 7A to 7H are views showing examples of cross-sectional shapes different from those of projections formed on the rear covers shown in FIGS. 1 to 6 ;
FIG. 8 is a schematic view showing an example of a rear cover constituting a turret of a second embodiment of the tool changer according to the present invention;
FIG. 9 is a schematic view showing a first modification of the rear cover shown in FIG. 8 ;
FIGS. 10A to 10D are schematic views showing a second modification of the rear cover shown in FIG. 8 ;
FIG. 11 shows an example of a conventional technique in which a tool changer comprising a turret with cover means is attached to a machine tool; and
FIG. 12 is a view showing a rear cover constituting a turret of the tool changer of FIG. 11 .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A first embodiment of a tool changer according to the present invention will first be described with reference to FIGS. 1 to 6 .
FIG. 1 is a view showing an example of a rear cover 602 constituting a turret of the first embodiment of the tool changer according to the present invention. A projection 607 is provided on an upper part of an outer rear surface portion 603 of the rear cover 602 . The projection 607 is semicircular in cross-section, arranged so that its central portion is higher than its opposite end portions, and inverted V-shaped as a whole. Thus, chips and cutting fluid drop along a flow passage defined by the outer rear surface portion 603 and the projection 607 of the rear cover 602 , as indicated by arrows C and D in FIG. 1 , so that they can be prevented from getting into a turret mechanism portion 604 . Also if the chips and cutting fluid are collected on an upper part of an outer truncated-cone portion 605 of the rear cover 602 , in the tool changer of the type in which the turret 6 is swung during tool change, they drop along the passage indicated by arrows C and D in FIG. 1 , so that they can be prevented from getting into the turret mechanism portion 604 .
As described above, FIG. 1 shows the example in which the projection 607 having the semicircular cross-section is formed in the shape of an inverted V on the upper part of the outer rear surface portion 603 of the rear cover 602 . However, the projection 607 is not limited to this shape and some modifications, such as those shown in FIGS. 2 to 6 , can be effected.
In a first modification of the rear cover 602 , as shown in FIG. 2 , a projection 608 having a semicircular cross-section is formed on the upper part of the outer rear surface portion 603 so that its central portion is higher than its opposite end portions, and is curved as a whole. Also in this modification, chips and cutting fluid drop outward from the central portion of the rear cover 602 (or the outer rear surface portion 603 ), so that they can be prevented from getting into the turret mechanism portion 604 .
In a second modification of the rear cover 602 , as shown in FIG. 3 , a projection 609 having a square cross-section is formed on the upper part of the outer rear surface portion 603 so that its upper side extends horizontally and its left and right sides continuous with the upper side are declined, and is trapezoidal as a whole. Also in this modification, chips and cutting fluid drop downward along the left and right sides from the upper side of the projection 609 of the outer rear surface portion 603 of the rear cover 602 after they are temporarily collected on the upper side. Thus, the chips and cutting fluid can be prevented from getting into the turret mechanism portion 604 .
In a third modification of the rear cover 602 , as shown in FIG. 4 , an inverted U-shaped projection 610 is formed on the upper part of the outer rear surface portion 603 so as to enclose the upper, left, and right sides of the turret mechanism portion 604 (see FIG. 12 ). In this modification, chips and cutting fluid outwardly drop left and right from the central portion of the projection 610 of the outer rear surface portion 603 of the rear cover 602 (or a curved portion of the projection 610 above the turret mechanism portion 604 ). Thereafter, they are dropped along the rear cover 602 by left and right straight portions of the projection 610 (or straight portions located individually on the left and right of the turret mechanism portion 604 ). Thus, the chips and cutting fluid can be prevented from getting into the turret mechanism portion 604 .
In a fourth modification of the rear cover 602 , as shown in FIG. 5 , a projection 611 on the upper part of the outer rear surface portion 603 comprises an inverted V-shaped first portion located above the turret mechanism portion 604 and straight second portions located individually on the left and right of the turret mechanism portion 604 . The projection 611 has substantially the same function as that of the third modification of the rear cover 602 ( FIG. 4 ).
In a fifth modification of the rear cover 602 , as shown in FIG. 6 , a projection 612 is provided also on the truncated-cone portion 605 of the rear cover 602 shown in FIG. 4 (third modification). Specifically, the rear cover 602 is provided with an inverted U-shaped projection (first projection 610 ) identical to that shown in FIG. 4 on the upper part of the outer rear surface portion 603 and a projection (second projection 612 ) on the upper part of the truncated-cone portion 605 . In this modification, chips and cutting fluid dropped on the truncated-cone portion 605 of the rear cover 602 are guided to the first projection 610 by a flow passage defined by the second projection 612 and then outwardly drop left and right from the central portion of the first projection 610 . Thus, the chips and cutting fluid can be prevented from getting into the turret mechanism portion 604 .
The projections 608 and 609 formed on the outer rear surface portion 603 of the rear cover 602 shown in FIGS. 2 and 3 are semicircular or square in cross-section. However, the cross-sections of these projections are not limited to such shapes and may also be of various other shapes, as shown in FIGS. 7A to 7H .
Projections shown in FIGS. 7A and 7F are shaped so that a portion having a square cross-section projects outward from a cover material. Projections shown in FIGS. 7B and 7C are shaped so that a portion having a triangular cross-section projects outward from a cover material. Projections shown in FIGS. 7D and 7G are shaped so that a portion having a trapezoidal cross-section projects outward from a cover material. Projections shown in FIGS. 7E and 7H are shaped so that a portion having a semicircular cross-section projects outward from a cover material. The projections of the various cross-sectional shapes shown in FIGS. 7A to 7H on the outer rear surface portion 603 of the rear cover 602 , like the projections of the shapes shown in FIGS. 1 to 6 , can prevent chips and cutting fluid from getting into the turret mechanism portion 604 .
A second embodiment of the tool changer according to the present invention will now be described with reference to FIGS. 8 to 10 .
FIG. 8 is a view showing an example of a rear cover 602 constituting a turret of the second embodiment of the tool changer according to the present invention. A recess 613 is provided in an upper part of an outer rear surface portion 603 of the rear cover 602 . The recess 613 is semicircular in cross-section, arranged so that its central portion is higher than its opposite end portions, and inverted V-shaped as a whole. Thus, chips and cutting fluid drop along a flow passage defined by the outer rear surface portion 603 and the recess 613 of the rear cover 602 , as indicated by arrows E and F in FIG. 8 , so that they can be prevented from getting into a turret mechanism portion 604 . Also if the chips and cutting fluid are collected on an upper part of a truncated-cone portion 605 of the rear cover 602 , in the tool changer of the type in which the turret 6 is swung during tool change, they drop along the passage indicated by arrows E and F in FIG. 8 , so that they can be prevented from getting into the turret mechanism portion 604 .
FIG. 9 shows a modification of the recess 613 shown in FIG. 8 . A first recess 614 , like the recess 613 of FIG. 8 , is semicircular in cross-section, and comprises a first portion, which is arranged so that its central portion is higher than its opposite end portions and is inverted V-shaped as a whole, and straight second portions located individually on the left and right of the turret mechanism portion 604 . Further, a second recess 615 is formed on the upper part of the truncated-cone portion 605 of the rear cover 602 . In this modification, chips and cutting fluid dropped on the truncated-cone portion 605 of the rear cover 602 are guided to the first recess 614 by a passage defined by the second recess 615 and then drop outward from the central portion of the first recess 614 . Thus, the chips and cutting fluid can be prevented from getting into the turret mechanism portion 604 . Furthermore, a suitable modification may be made such that the first portion of the first recess 614 , which is arranged so that its central portion is higher than its opposite end portions and is inverted V-shaped as a whole, and the straight second portions located individually on the left and right of the turret mechanism portion 604 are formed continuously with each other or that the second recess 615 of the truncated-cone portion 605 is omitted.
The recesses 613 and 614 formed in the outer rear surface portion 603 of the rear cover 602 shown in FIGS. 8 and 9 are semicircular in cross-section. However, the cross-sections of these recesses are not limited to this shape and may also be of various other shapes, as shown in FIGS. 10A to 10D .
A recess shown in FIG. 10A is formed by inwardly extruding a portion having a triangular cross-section from a cover material. A recess shown in FIG. 10B is formed by inwardly extruding a portion having a square cross-section from a cover material. A recess shown in FIG. 10C is formed by inwardly extruding a portion having a semicircular cross-section from a cover material. A recess shown in FIG. 10D is formed by inwardly extruding a portion having a trapezoidal cross-section from a cover material. The recesses of the various cross-sectional shapes shown in FIGS. 10A to 10D in the outer rear surface portion 603 of the rear cover 602 , like the recesses of the shapes shown in FIGS. 10A to 10D , can prevent chips and cutting fluid from getting into the turret mechanism portion 604 .
In the embodiments and modifications described above, the projections or recesses that define the cutting fluid passages are provided in the upper part of or in the upper part and the left and right side portions of the outer rear surface portion 603 of the rear cover 602 . However, in a case where another member is provided in the upper part of the outer rear surface portion 603 , for example, chips and cutting fluid can be prevented from getting into the turret mechanism portion 604 by simply providing projections or recesses for passages at only the left and right side portions of the outer rear surface portion 603 .
In above-described embodiments and modifications, moreover, only the projections or recesses are used as members that define flow passages. Alternatively, however, projections and recesses may be used in a mixed manner.
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A tool changer comprises a turret with a plurality of grips for holding tools such that the turret is turned to index a desired tool to change the tools. The front and rear surfaces of the turret are covered by front and rear covers, respectively. A projection or a recess which defines a passage for cutting fluid is formed in an outer rear surface portion of the rear cover at portions above and/or on each lateral side of a turret mechanism portion.
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FIELD OF THE INVENTION
This invention relates to troughed idlers for use in a bulk material handling system, and, more particularly, it relates to a double-walled plastic roller having blind sockets formed within self-lubricating plastic bearing members for receiving stainless steel bearings.
CROSS-REFERENCES
This is an improvement over the application Ser. No. 457,859, filed Apr. 4, 1974, now U.S. Pat. No. 3,931,878. This application is assigned to the same assignee as the above-referenced application.
DESCRIPTION OF THE PRIOR ART
Bulk material conveyors commonly carry loose material upon a conveyor belt looped around a set of drive pulleys and rotatably supported by rollers placed at spaced apart locations along the conveyor belt's path. The bulk material, such as sand, gravel, grain, sugar, fertilizer, cement, etc., being in a nonpackaged loose state, would spill over the edge of a flat belt, so the outer roller or rollers on each side of the belt are inclined to form a depression or trough in the center of the belt to carry loose material in the center of the troughed belt. The bulk material deposited at one end of the continuous conveyor belt is carried in this fashion to an unloading area where the belt travels around a pulley to discharge material at this point. The empty belt is returned underneath the conveyor frame assembly and is supported by a number of flat return idlers.
Heretofore, the troughed rollers for supporting the conveyor belt have been made of steel or other metal to provide the necessary rigidity and strength to support a loaded conveyor belt, while withstanding the turning torque stress produced by the advancing conveyor belt. Ball bearings have been used for rotatably supporting the rollers, but such bearings often fail because of exposure to moist or abrasive material getting inside the bearing, or lack of proper lubrication and maintenance. A roller that fails from any of these reasons locks up and cannot turn so that the belt wears through the steel wall of the roller, thereby cutting the belt with the sharp edges of the roller.
Moreover, some types of bulk material will adhere to the metal rollers, causing the belt to travel unevenly and track to one side. This can cause the belt to wear out from rubbing against the framework or dump material over the side since the belt is no longer properly troughed. Troughed rollers of the prior art require frequent lubrication and often fail because the bulk handling system are generally used in environments such as in overhead framework, in tunnels, in mines, or underground that make lubrication difficult or impossible. In addition, steel rollers now in use require excessive horsepower to overcome the initial start-up inertia present in such a bulk handling system, as well as excessive energy losses from keeping the steel rollers turning.
The troughed roller of the present invention overcomes many of the disadvantages associated with the prior art devices. Lubrication problems are eliminated since the troughed roller of the present invention does not require any lubricants. The lightweight plastic material utilized in constructing the present troughed roller results in a roller that is only one third the weight of a conventional metal roller. This reduction in the weight of the rollers reduces the horsepower requirements to operate the bulk handling system, enabling it to conserve energy.
SUMMARY OF THE INVENTION
The present invention provides a highly durable lightweight plastic troughed roller, offering reduced maintenance and operating costs when used in a bulk material handling system.
In accordance with the present invention, an outer plastic elongated tube for supporting an advancing conveyor belt has an inner plastic elongated tube concentrically disposed within the outer tube. A pair of cylindrical plastic end pieces, having an aperture extending through the center of each, are dimensioned so that the end of the inner tube is closely received within the aperture, while the exterior cylindrical surface of the end piece is received within the end of the outer plastic tube. The outer and inner plastic tubes are rigidly interconnected to the end pieces. Self-lubricating plastic bearing members are dimensioned to be closely received within the apertured plastic end pieces. Annular flanges formed on the outer end of the bearing members regulate the bearing members seating depth within the end pieces. A blind socket is formed in center of the outer end of the bearing members to receive a generally spherical bearing.
In accordance with another aspect of the invention, an improved hollow cylindrical roller for use in a troughed roller assembly has self-lubricating plastic bearing members rigidly mounted in the ends of the rollers, each bearing member having a blind right circular cylindrical socket formed in its center. A plurality of opposed metal stub shafts having generally spherical bearing portions are located at spaced apart locations for being closely received within the blind sockets to rotatably suspend the roller carried thereby between.
In accordance with yet another aspect of the invention, an improved hollow cylindrical roller for use in a troughed roller assembly includes low friction self-lubricating plastic bearing members rigidly mounted in the ends of the rollers with a blind right circular cylindrical socket formed in the end of the bearing members. Two metal stub shafts located at each end of the roller assembly have generally spherical bearing portions on one end for being received with the blind socket in the outer end of the two inclined rollers. The interior roller supports include two curved metal stub shafts with generally spherical bearing portions formed on each end thereof, one bearing portion of each being received within the blind sockets of a central roller to rotatably suspend it, while the bearing portion on the other end of the curved metal stub shaft is closely received within the blind socket of the inner bearing member of the inclined rollers to thereby form a troughed roller assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention and further objects and advantages thereof, reference is now made to the following description taken in conjunction with the following drawings:
FIG. 1 illustrates an elevated side view of a bulk material handling system utilizing troughed rollers.
FIG. 2 illustrates a front view taken along the lines 2--2 of FIG. 1.
FIG. 3 illustrates an alternate embodiment of the troughed roller assembly of the present invention shown in FIG. 2.
FIG. 4 illustrates a cut away side view of a troughed roller of the present invention. p FIG. 5 illustrates a cut away side view of a troughed roller of the present invention with an alternately shaped blind socket.
FIG. 6 illustrates a side view of the bearing portion and stub shaft employed in the present invention.
FIG. 7 illustrates a side view of an interior stub shaft having two bearing portions formed on an end thereof.
FIG. 8 illustrates a bottom view of the interior stub shaft shown in FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates a side view of a typical bulk material handling system, generally referred to by the numeral 10. The system 10 employs a plurality of troughed rollers 12 of the present invention. As shown in FIG. 1, a troughed roller support assembly 14 utilizes one troughed roller 12 in the middle surrounded by two inwardly inclined troughed rollers 12 to form a trough or depression therebetween. The trough roller support assembly 14 is in turn rigidly mounted upon a conveyor frame 16, which includes a plurality of flat return idlers 18.
A continuous conveyor belt 20 is shown looped around a pair of drive pulleys 22 and 24 to advance the belt over the troughed roller assemblies 14 in the direction shown by arrow 26. The conveyor belt 20 is flexible so that it conforms to the troughed shaped roller assemblies 14. The drive pulleys 22 and 24 are in turn driven by a power source (now shown) to control the operation of the bulk material handling system 10.
In a typical operation, a bulk material 28 is discharged from a hopper 30 at one end of the troughed conveyor 20. The bulk material 28 is thus carried by conveyor belt 20 as long as the material 28 is retained within this depression. The bulk material 28 is carried in the direction shown by arrow 26 until it is discharged at a point 32 as the conveyor belt 20 returns to a flat shape as it passes over the pulley 24. The flat conveyor belt 20 is now carried upon a series of flat return idlers 18 until it loops around drive pulley 22 to the point where it receives additional material from discharge hopper 30. (The flat return idlers 18 may be constructed similar to the troughed roller 12, described below, to eliminate lubrication for the idlers 18.)
FIG. 2 illustrates a front view of the troughed roller assembly 14 taken along the lines 2--2 of FIG. 1. The troughed roller assembly 14 includes a pair of exterior roller support arms 40 extending upwards from the conveyor frame 16. The ends of the exterior roller support pieces 40 are bent inwardly to achieve the desired angle of inclination for the troughed rollers 12. A stub shaft bearing assembly, generally referred to by the numeral 42, is secured in the inclined ends of each of the exterior roller supports 40 for being received by an inclined roller 12.
A pair of interior roller supports 44 are rigidly mounted to the conveyor frame 14 to support stub shaft bearing assemblies 42 for the central troughed roller 12 located therebetween and the stub shaft bearing assemblies 42 for the interior end of each of the inclined troughed rollers 12. Each of the interior roller supports 44 orients the opposed stub shaft bearing assemblies 42 so that the central troughed roller 12 has its axis of rotation parallel to the plane containing the conveyor frame 16. In addition, each of the interior roller support assemblies 44 supports a stub shaft bearing assembly 42 for the interior ends of the inclined troughed rollers 12 at the desired angle of inclination "a." The troughed rollers 12 in combination with the stub shaft bearing assemblies 42 are shown in greater detail in FIGS. 4 and 5 below.
FIG. 3 illustrates a curved stub shaft bearing assembly 50 to be supported by a pair of interior troughed roller supports 52. The stub shaft bearing assembly 50 is curved to incline the rollers 12 at the desired angle of inclination "a." Each stub shaft bearing assembly 50 rotatably supports the central troughed roller 12 and the inner end of each of the inclined troughed rollers 12. (The curved bearing assembly 50 is described in greater detail below in the description of FIGS. 8 and 9.)
FIG. 4 illustrates a cut away side view of the troughed roller 12 shown in FIGS. 1-3. An inner elongated hollow plastic tube 54 is concentrically disposed within an outer hollow elongated plastic tube 56. Concentric tubes 54 and 56 may be made from polyvinyl chloride or a similar light-weight plastic. A plastic cylindrical end piece 58 having an aperture 60 formed in the center thereof holds the concentric tubes 54 and 56 together to form the basic configuration for the troughed roller 12. The outside diameter of the cylindrical end piece 58 is dimensioned to be closely received within the outer tube 56, while the inner diameter of end piece 58 created by the aperture 60 is dimensioned to closely receive the inner tube 54. An annular flange 62 is formed around the outer perimeter of the cylindrical end piece 58 to regulate the seating depth of the end piece 58 within the outer tube 56. Similarly, an interior annular flange 64 regulates the seating depth of the inner tube 54 within the end piece 58.
Notches 66 are cut around the interior and exterior cylindrical surfaces of the end pieces 58 to provide a means for rigidly connecting the concentric inner and outer tubes 54 and 56 to the end pieces 58. The interior and exterior cylindrical surfaces around the notches 66 are coated with an appropriate solvent or cement before assembly. The adjoining surfaces of the inner and outer tubes 54 and 56 dissolve or swell into these notches 66 to rigidly interconnect the rollers 54 and 56 to end pieces 58 when the solvent or cement hardens the plastic in these notches 66. The troughed roller assembly consisting of the inner tube 54, outer tube 56 and two end pieces 58 are now fused into one solid piece.
The plastic construction of the troughed roller 12 gives it a greater resiliency than the conventional steel troughed roller of the prior art. However, at particular points along the advancing conveyor belt, like the load point, additional resiliency or give may be desired in the roller to prevent cuts and abrasions in the rubber belt 20 from bulk material having sharp and irregular edges. To achieve greater resiliency, a high impact styrene, such as "Styrofoam", may be foamed in place in the interstices 68 between the concentric hollow tubes 54 and 56. Additional resiliency may be obtained by foaming the high impact styrene in the hollow space 70 within the inner plastic tube 54. It is understood of course that such highly resilient troughed rollers 12 may be used throughout the bulk material handling system 10 to reduce the wear on the belt from heavy bulk material that has numerous sharp and protruding edges.
A self-lubricating plastic cylindrical bearing member 72 is dimensioned to be closely received within the aperture 60 of each of the end pieces 58. The outside diameter of the bearing member 72 is slightly greater than the interior diameter of the overlapping edge of the interior tube 54 to provide an interference fit when the bearing member 72 is pressed into place. The cylindrical bearing members 72 may be made from a plastic material known commercially as "LUBRA-TUF" (a specially processed UHMW polyethylene) that has a low coefficient of friction. The cylindrical bearing members 72 have right circular cylindrical blind sockets 74 formed in the center of the outer ends of the bearing members 72. The blind sockets 74 of the bearing member 72 shown in FIG. 4 extends to a concave inner end surface 75. With the cylindrical bearing members 72 pressed into place, the plastic trough roller 12 is completely sealed, preventing any possible entry of foreign or gaseous matter into the interior of the hollow roller 12. Preventing the entry of foreign matter into the hollow troughed roller 12 would be of great advantage in many environments where bulk material handling systems are used. For example, in the fertilizer industry, fumes from the fertilizer pass through the ball bearings supporting the hollow steel rollers of a prior art trough roller, thereby filling the interior of the roller with an explosive gas. The failure of a bearing can cause either heat or generate a spark to explode the roller. Such problems are eliminated by the trough roller 12 of the present invention.
FIG. 4 also illustrates the stub shaft bearing assembly 42 received within the blind socket 74 of the troughed roller 12. The assembly 42 includes a stub shaft 76 with a generally spherical bearing portion 78 formed on the end thereof. The end of the stub shaft 76 is rigidly mounted to an exterior support assembly 40 or an interior roller support 44, as described above in FIG. 2. The spherical bearing portion 78 is dimensioned to be closely received within the blind socket 74 of the bearing member 72. In the configuration shown in FIG. 4, the bearing portion 78 extends inwardly and conforms to the concave inner end surface 75 of the blind sockets 74. This particular configuration evenly distributes the load forces produced by the belt 20 carrying a bulk material 28.
FIG. 5 illustrates an alternate embodiment of the stub shaft bearing assembly 42 in the bearing member 72. In this configuration, the blind socket 74 extends to a flat planar inner end surface 80, and the spherical bearing 78 received within the blind sockets 74 extends inwardly to tangentially engage inner end surface 80. This point contact configuration of the bearing 78 in the blind socket 74 is more suitable for use in a bulk material handling system where the belt 20 is carrying a lighter weight bulk material, and the system operates at higher speeds.
FIG. 6 illustrates an alternate stub shaft bearing assembly 82 for use in conjunction with the troughed roller 12 described above. The stub shaft bearing assembly 82 has a cylindrical stub shaft 84 made from a metal, such as aluminum, having a relatively high coefficient of thermal conductivity. A generally spherical bearing portion 86 is formed on the end of the stub shaft 84, since it is desirable to have a metal with a high abrasion resistance to be received within the cylindrical bearing member 72. Considerable heat builds up in the blind socket 74 of the bearing member 72 when the troughed rollers 12 are operated under heavy loads for an extended period of time. The build up of heat within the blind socket 74 decreases the life of the bearing member 72, while increasing the friction between the bearing 78 and bearing member 72. The stub shaft bearing assembly 82 conducts heat away from the stainless steel bearing 86 through the aluminum stub shaft 84 to the troughed roller supports 40 and 44 (see FIG. 2).
FIGS. 7 and 8 illustrate an alternate embodiment of a stub shaft and bearing combination to rotatably support the troughed rollers. The one piece curved stub shaft bearing member 50 has a central curved stub shaft section 90 with two spherical bearing portions 92 formed on each end thereof. The stub shaft 90 is curved at an angle "a" which is the desired angle of inclination of the inclined trough roller 12 (not shown). The stub shaft 90 has notches 94 formed on either side thereof so shaft 90 may be adjustably received within an interior roller support 52. The notches 94 enable the stub shaft bearing member 50 to be correctly positioned within the support member 52. The stub shaft bearing member 50 reduces the number of parts in a bulk material handling system when it is used to rotatably suspend a central troughed roller 12 therebetween and the inner end of each of the inclined rollers 12. The stub shaft bearing member 50 also may have its bearing members 92 made from stainless steel while the angle shaft portion 90 is made from aluminum, having a higher coefficient of thermal conductivity, to conduct heat away from the bearing members to prolong the life of the troughed rollers.
It is to be understood, of course, that the bulk material handling system 10 shown in FIGS. 1-3, described hereinabove, is not limited to that configuration employing three troughed rollers 12. The troughed roller support assembly 14 may support any number of troughed rollers 12 to form the desired trough shape to support conveyor belt 20 thereon. For example, the troughed roller support assembly 14 may include two inclined troughed rollers 12 that are proximally located to one another to form a suitable trough for supporting a conveyor belt 20 at the desired angle of inclination "a."
Such a material handling system 10 employing two troughed rollers 12 could employ a centrally located roller support, similar to interior roller support 44 shown in FIG. 2. Such a centrally located roller support assembly could angularly support two stub shaft bearing assemblies, similar to bearing assemblies 42 shown in FIG. 2, for rotatably supporting the interior opposing ends of the inclined troughed rollers 12. The outer ends of the troughed rollers 12 might be supported by a pair of stub shaft bearing assemblies located on exterior roller support arms, similar to roller support arms 40.
In an alternate embodiment of a material handling system 10 employing two inclined troughed rollers 12, the central roller support assembly could be rotatably supported by a curved bearing assembly, such as bearing assembly 50 shown in FIG. 7, and supported on an interior troughed roller support similar to roller support 52 shown in FIG. 3. The desired angle of inclination "a" a of the troughed rollers 12 would be determined by the curvature of the bearing support assembly. The outer ends of the troughed rollers 12 could be supported in the manner shown in FIG. 2 and described hereinabove.
Although preferred embodiments of the invention have been illustrated in the accompanying drawings and described in the foregoing detailed description, it will be understood that the invention is not limited to the embodiments disclosed, it is capable of numerous rearrangements, modifications, and substitution of parts and elements without departing from the spirit of the invention.
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Two concentric tubes made from a lightweight plastic are locked together by two plastic cylindrical end pieces having an aperture formed in the center thereof. The outer plastic tube rotatably supports an advancing conveyor belt carrying a bulk type material, while the inner plastic tube receives the turning torque stress. Self-lubricating plastic bearing members having blind sockets formed in the center thereof are dimensioned to be inserted in the ends of the roller. Stub shafts having generally spherical stainless steel bearing portions formed on the ends thereof are closely received within the blind sockets to rotatably suspend the roller assembly therebetween. Under such high speed, heavy-duty operations the heat built up in the stainless steel bearing is dissipated through an aluminum stub shaft to the frame assembly for the bulk material handling system. In one embodiment, the cylindrical bearing members of a central idler and an adjoining inclined idler are rotatably supported by a single curved stub shaft having generally spherical bearing portions formed on both ends for being received within the blind sockets of these bearing members.
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CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND OF THE INVENTION
The present invention is related to a method for the operation of a wind energy plant with voltage-dependent control of a reactive electric variable which is to be provided, in which a desired value for the reactive electric variable is calculated.
Today's wind parks are required to be voltage-supportingly connected with the electric grid. It is therefore provided that a voltage-dependent reactive power is provided by the individual wind energy plants and/or by the wind park as a whole. This is also designated as an Automatic Voltage Regulation (AVR), and it serves to keep the voltage constant in the grid by providing reactive power and/or reactive current at voltage fluctuations which remain in certain ranges.
From EP 1 282 774, the entire contents of which is incorporated herein by reference, a method for the operation of a wind energy plant with a generator is known, which generates electric power for an electric supply grid. In the wind energy plant it is dealt with a pitch-controlled plant, the power of which is controlled and/or adjusted depending on the grid frequency. Further, it is known that the supplied power is reduced when the grid frequency exceeds a reference value for the grid frequency for more than 3%.
From EP 1 386 078, the entire contents of which is incorporated herein by reference, it is known to change the phase angle depending on the absolute value of a voltage detected in the supply grid. In this, the phase angle remains unchanged inside a dead band. When leaving the dead band, the absolute value of the phase angle, which describes the reactive portion of the power, is increased at rising or decreasing voltage.
From EP 1 508 951 A1, the entire contents of which is incorporated herein by reference, it is known to adapt the reactive power which is to be provided dynamically, depending on parameters of the wind energy plant.
The present invention is based on the objective to provide a method for the operation of a wind energy plant, in which can be reacted to voltage changes by providing a reactive electric variable in a time which is as short as possible.
BRIEF SUMMARY OF THE INVENTION
The invention is related to a method for the operation of a wind energy plant with voltage-dependent control of a reactive electric variable which is to be provided. In the method of the invention, a desired value for the reactive electric variable is calculated. In doing so, the method of the invention presumes that a first upper and/or a first lower limit value of the grid voltage is defined for the grid voltage. Thus, according to the invention, three variants of the method of the invention are embraced, which are related to the case that (first) only a first upper limit value, (second) only a first lower limit value and (third) a first upper limit value as well as a first lower limit value are defined. The method of the invention provides that when the real value of the grid voltage exceeds the first upper limit value, the desired value of the reactive electric variable is increased or diminished such that the deviation of the real value of the grid voltage from its desired value is counter-acted. Also, in the variants two and three, the method of the invention provides that when falling below the first lower limit value, the desired value of the reactive electric variable is increased or diminished such that the deviation of the real value of the grid voltage from its desired value is counter-acted. According to the invention, the desired value of the reactive electric variable is continuously increased or diminished further over the time, as long as the real value of the grid voltage exceeds the first upper limit value or falls below the first lower limit value. Thus, in the method of the invention, a change of the desired value of the reactive electric variable continuous over the time is initiated when the first upper limit value is exceeded and/or the first lower limit value is under-run. This change continues as long as the real values of the grid voltage are above or below the first upper limit value or the first lower limit value, respectively.
In the context of the provision of reactive power, different expressions are used in the art:
For instance, it may be spoken of the provision of capacitive or inductive reactive power, the supply or the withdrawal of reactive power or of an over-excited and an under-excited operation. In the following, if not mentioned otherwise expressively, it is always spoken of a voltage-increasing reactive power or of a voltage-decreasing reactive power, respectively. In the consideration of wind energy plants on the grid, different algebraic sign conventions have also been established in the context of reactive electric variables, let it be electric reactive power or the electric reactive current. In the following, a positive sign is used for voltage-increasing reactive power and a negative sign for voltage-decreasing reactive power.
In a preferred extension of the method of the invention, the first upper limit value of the grid voltage is greater than the desired value or equal to the desired value for the grid voltage. Also, the first lower limit value of the grid voltage is smaller than the desired value or equal to the desired value of the grid voltage. Thus, first upper and lower limit values are preferably above and below the desired value for the grid voltage, respectively.
In a preferred embodiment, the desired value of the reactive electric variable is increased or diminished until the desired value has reached a maximum value or a minimum value. In this preferred embodiment, the change of the desired value for the reactive electric variable is stopped when the desired value has reached a predetermined maximum or minimum value. The advantage of this limitation is that when the wind energy cannot develop a grid-supporting function, from on a certain provided maximum or minimum value, further increase or lowering of the reactive electric variable is interrupted.
In a preferred embodiment, a second lower limit value is defined in addition, which is smaller or equal to the first upper limit value. When the real value of the voltage falls below the second lower limit value, the desired value for the reactive electric variable is continuously increased or diminished over the time, for so long until a first predetermined desired value for the reactive electric variable has been reached. In analogy to this, a second upper limit value is also preferably defined, which is greater or equal to the first lower limit value, wherein when the real value of the voltage exceeds the second upper limit value, the desired value of the reactive electric variable is continuously increased or diminished over the time, for so long until a second predetermined desired value for the reactive electric variable has been reached. The additional second upper and lower limit values permit to define a voltage range in which increasing and lowering to predetermined desired values for the reactive electric variable are possible, respectively. In a preferred embodiment, the predetermined desired values for the first and the second reactive electric variable are equal, particularly preferred both desired values have the value zero. Thus, in this embodiment, the desired value for the reactive electric variable is set back to the value zero when the second lower limit value was under-run. By the introduction of the second upper and lower limit value, an at least partially continuous control can be exerted.
In a preferred embodiment, the desired value for the reactive electric variable is set to a value which is constant over time when the real value of the grid voltage falls below the first upper limit value again, and/or exceeds the first lower limit value again. In this, the value which is constant over time for the reactive electric variable is preferably equal to the actual desired value of the reactive electric variable in the point of time when the same exceeds the first lower limit value again or falls below the first upper limit value again, respectively. Thus, in this embodiment, when the real value of the grid voltage enters again into the range defined by the first upper limit value and the first lower limit value, the desired value for the reactive electric variable is kept constant at its actual value. In analogy to the embodiment of the method of the invention described above, in which the value which is constant over time is provided for the reactive variable, it may also be provided that when the real value of the grid voltage exceeds the second lower limit value again, and/or falls below the second upper limit value again, the desired value for the reactive electric variable is set to a value which is constant over time. In doing so, the value constant over time can be preferably the actual desired value of the reactive electric variable again.
In a preferred embodiment of the method of the invention, the second upper limit value of the grid voltage is smaller or equal to the first upper limit value of the grid voltage. Also, the second lower limit value of the grid voltage is preferably greater or equal to the first lower limit value of the grid voltage.
For those skilled in the art, it is commonly known that there are plural possibilities of the representation of reactive electric variables: reactive power, reactive current, phase angle or power factor.
Also, it is commonly known to those skilled in the art that for providing and influencing a reactive electric variable, control of the generator and/or the converter system and/or the phase shifter system can be applied.
In a preferred embodiment of the method of the invention, the limit values can be set with respect to the desired value for the grid voltage.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
The method of the invention will be explained in more detail by means of an example in the following.
FIG. 1 shows a depiction of the determination of the desired value for the reactive power depending on the measured voltage,
FIG. 2 shows a depiction of an alternative determination of the desired value for the reactive power depending on the measured voltage,
FIG. 3 shows an exemplary course of the voltage and of the desired value of the reactive power over the time,
FIGS. 4 and 5 show depictions of further alternative determinations of the desired value for the reactive power depending on the measured voltage, and
FIG. 6 shows a depiction of the determination of the desired value according to FIG. 1 with another choice of the algebraic signs.
DETAILED DESCRIPTION OF THE INVENTION
While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated
FIG. 1 shows the values for the grid voltage U on the abscissa, wherein U N indicates a desired value for the grid voltage. Along the ordinate, values for the reactive power Q are plotted, wherein a voltage-increasing reactive power is plotted above the abscissa, and a voltage-decreasing reactive power below the abscissa.
When the grid voltage increases, the control method of the invention does not intervene and it does not change the actual desired value for the reactive power until the first upper limit value U 1 is reached. Only when the limit value U 1 is exceeded, lowering of the desired value for the reactive power takes place, i.e. voltage-decreasing reactive power is provided. The desired value for the reactive power is subsequently lowered further and further over time for so long until either a limit value of the reactive power Q min is reached or until the limit value of the voltage U 1 is under-run again. Thus, the desired value of the reactive power is lowered further and further from on the point of time in which the limit value U 1 was exceeded, corresponding to the duration of the transgression of the limit value U 1 , wherein for instance, the lowering of the desired value can take place in a constant amount per unit time: dQ/dt=const. When a limit value of the reactive power Q min is reached, the desired value for the reactive power is kept constant on that value from on this point of time, as indicated in FIG. 1 through the dashed portion at Q min .
When the grid voltage falls below the limit value U 1 again, the desired value for the reactive power is kept constant again, namely on the desired value reached up to this point of time.
Only when the grid voltage falls even below the second lower limit value U 2 , the desired value for the reactive power is increased again, namely from on the point of time of under-running the limit value U 2 , corresponding to the duration of under-running the limit value U 2 . The desired value for the reactive power is further increased for so long until a predetermined reactive power desired value, zero for instance, has been reached or until the limit value U 2 has been exceeded again through a new increase of the grid voltage. Thereafter, the reactive power desired value is kept constant again, namely on the desired value reached up to this point of time.
When the grid voltage drops down, the control method of the invention does not intervene and it does not change the actual desired value for the reactive power until the first lower limit value U 3 is reached. Only when the limit value U 3 is under-run, increase of the desired value for the reactive power takes place, i.e. voltage-increasing reactive power is provided. The desired value for the reactive power is subsequently increased further and further over time for so long until either a limit value of the reactive power Q max is reached or until the limit value of the voltage U 3 is exceeded again. Thus, the desired value of the reactive power is increased farther and further from on the point of time in which the limit value U 3 was under-run, corresponding to the duration of falling below the limit value U 3 , wherein for instance, the increase of the desired value can take place in a constant amount per unit time: dQ/dt=const. When a limit value of the reactive power Q max is reached, the desired value for the reactive power is kept constant on that value from on this point of time, as indicated in FIG. 1 through the dashed portion at Q max .
When the grid voltage exceeds the limit value U 3 again, the desired value for the reactive power is kept constant again, namely on the desired value reached up to this point of time.
Only when the grid voltage exceeds even the second upper limit value U 4 , the desired value for the reactive power is lowered again, namely from on the point of time of the transgression of the limit value U 4 , corresponding to the duration of the transgression of the limit value U 4 . The desired value for the reactive power is further lowered for so long until a predetermined reactive power desired value, zero for instance, has been reached or until the limit value U 4 has been under-run again through a new drop of the grid voltage. Thereafter, the reactive power desired value is kept constant again, namely on the desired value reached up to this point of time.
FIG. 2 shows an alternative embodiment of the method, wherein the limit values U 2 and U 4 are equal. The position of the desired value rated voltage U N is not indicated here, it may be situated in the interval between U 3 and U 1 at any position and has not to coincide with U 2 or U 4 , respectively.
Presumed a desired value of the reactive power is set below the abscissa (=voltage decreasing reactive power) and the grid voltage coming from the interval between U 2 and U 1 drops below the limit value U 2 , the desired value of the reactive power is increased until the preset value (zero for instance) is reached, and then it is kept constant at this preset value. Only when the limit value U 3 was under-run in a further drop of the grid voltage, the desired value of the reactive power is increased further.
In the reverse case that a desired value of the reactive power above the abscissa is set (=voltage-increasing reactive power), and the grid voltage coming from the interval between U 3 and U 4 increases further above U 4 , the desired value of the reactive power is correspondingly decreased at first, until the preset value (for instance, zero) is reached, and thereafter it is kept constant. Only when the limit value U 1 is exceeded in a further rise of the grid voltage, the desired value of the reactive power is lowered further.
The concept which was set forth can be simply clarified by means of FIG. 3 . The upper part of FIG. 3 shows an exemplary course of the voltage over time. The first upper limit value of the voltage U 1 , the first lower limit value of the voltage U 3 and the second limit values U 2 and U 4 can be recognised, wherein U 2 =U 4 was chosen. Thus, this is equivalent to the depiction from FIG. 2 .
The lower part of FIG. 3 shows the corresponding course of the desired value of the reactive power Q over time, which results according to the method of the invention. The preset value zero, the upper limit value Q max and the lower limit value Q min can be recognised.
In the time interval between the point of origin and the point of time t 1 the voltage increases gradually, and in the point of time t 1 it reaches the first upper limit value U 1 . As can be recognised in the lower part of the diagram in FIG. 3 , the desired value of the reactive power remains constantly at the value zero up to the point of time t 1 . From on the point of time t 1 up to t 2 , the voltage exceeds the first upper limit value U 1 , and according to the invention, the desired value of the reactive power Q is lowered in the course of time, as long as the voltage exceeds the limit value U 1 . The linear decrease of the desired value for the reactive power results from the fact that a desired value decrement constant over time is defined, as is depicted in the description for FIG. 1 in the upside. In principle, non-linear forms are possible in the increment and/or decrement of the desired value. For instance, it is also possible to make the change of the desired value proportional to the voltage deviation, dQ/dt˜(U N −U ist ).
In the interval of time from t 2 up to t 3 , the voltage falls below the upper limit value U 1 , in this interval of time the desired value of the reactive power Q is kept constant at that value which had been reached up to the point of time t 2 . From on the point of time t 3 , the voltage exceeds the upper limit value U 1 again, and a lowering of the desired value for the reactive power Q constant over time takes place again. In the point of time t 4 , the limit value of the reactive power Q min is reached, from on this point of time the desired value of the reactive power Q is no more lowered further, but is kept constant on the value Q min , even though the voltage still remains above the upper limit value U 1 and occasionally even rises still further. In the point of time t 5 , the voltage falls below the upper limit value U 1 again, the desired value of the reactive power is further on kept constant on the value Q min which had been reached up to then. In the point of time t 6 , the voltage falls below the second lower limit value U 2 , therefore the desired value of the reactive power Q is raised again over the time. In the point of time t 7 , the lower limit value U 2 is exceeded again, and the desired value of the reactive power Q is kept constant on the value which had been reached up to then. From on the point of time t 8 , the lower limit value U 2 is under-ran again, therefore the desired value of the reactive power is raised further, until the preset value zero has been reached in the point of time t 9 . From on this point of time, the desired value of the reactive power Q is kept constant on the preset value zero.
From on the point of time too, the voltage falls below the first lower limit value U 3 , therefore, the desired value of the reactive power Q is increased over the time. From t 11 up to t 12 , the voltage reverts to the range between the limit values U 3 and U 4 , so that the desired value of the reactive power Q is kept constant in this interval of time, namely on the value which was reached in the point of time t 11 . From on t 12 , the voltage falls below the first lower limit value U 3 again, therefore the desired value of the reactive power Q is increased further, until the limit value Q max of the reactive power is reached in the point of time t 13 . From on t 13 , the desired value of the reactive power is kept constant for so long until the upper limit value U 4 of the voltage is exceeded again in the point of time t 14 . From on t 14 , the desired value of the reactive power Q is therefore lowered again over the time, and in the point of time t 15 it reaches the preset value zero, at which it is kept constant from on t 15 again.
Further variants of the method are depicted in FIGS. 4 and 5 . FIG. 4 shows a case in which the intervals between U 2 and U 1 or U 3 and U 4 , respectively, partly overlap each other.
FIG. 5 shows the case that the two intervals overlap each other completely. In this, the desired value of the reactive power is kept constant in the whole interval between U 3 and U 4 , and only when exceeding U 1 or falling below U 3 , respectively, a change of the desired value of the reactive power sets on.
Thus, FIGS. 1 , 2 , 4 and 5 show different examples how an adaptation of the method to different conditions of location and grid is possible by changing the limit values for the voltage U 1 . . . U 4 . In daily practice, the method will be implemented in such a manner that the limit values U 1 . . . U 4 can be changed in a simple way by changing operation parameters of the wind energy plant, or that the limit values are shifted corresponding to the desired value of the grid voltage U N .
In the same manner, by changing the limit values for the reactive power, Q min and Q max , a simple adaptation of the method is possible. For better exploitation of the technical capacity of the wind energy plant, it makes sense furthermore that the limit values Q min and Q max are matched to the momentary active power delivery and/or power reserve of the wind energy plant in the current operation. A suitable method is described in EP 1 508 951, the entire contents of which is incorporated herebin by reference, for instance.
FIG. 6 illustrates the method according to FIG. 1 for the case that the sign conventions are chosen otherwise, namely in the manner that reactive power above the abscissa acts voltage-lowering and reactive power below the abscissa acts voltage-increasing.
The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.
Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim 1 should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.
This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.
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A method for the operation of a wind energy plant, with control of a reactive electric variable which is to be provided, wherein a desired value for the reactive electric variable is determined as follows: a first upper and/or a first lower limit value of the grid voltage is defined for the grid voltage, when the real value of the grid voltage exceeds the first upper limit value and/or the real value of the grid voltage falls below the first lower limit value, the desired value of the reactive electric variable is increased or diminished such that the deviation of the real value of the grid voltage from its desired value is counter-acted, wherein the desired value of the reactive electric variable is continuously increased or diminished further over the time, as long as the real value of the grid voltage exceeds the first upper limit value or falls below the first lower limit value.
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FIELD OF THE INVENTION
[0001] The present invention relates to a frequency divider; more particularly, relates to operating a static frequency division and an injection-locking frequency division with the same circuit while lowering power consumption.
DESCRIPTION OF THE RELATED ARTS
[0002] General frequency dividers include static frequency dividers, dynamic frequency dividers and injection-locking frequency dividers, as what follows:
[0003] A. Static frequency divider: It has a differential structure of D-type flip-flop; requires an additional clock as a basic clock for a frequency division; has an operation speed depending on the equivalent loading capacitance of loads and transistors; has a capability of dividing frequency by 2 and a characteristic of wide frequency ranges for input/output frequency division; and, has a small circuit layout.
[0004] B. Dynamic frequency divider: It has a differential structure of T-type flip-flop; requires a feed back signal to be mixed with an input signal to run a division; consumes much power by a few transistors formed into stacks; and, is able to be operated in a wide band and a high frequency.
[0005] C. Injection-locking frequency divider: It has a basic oscillator structure, which is an inductor-capacitor (LC) tank structure or a ring structure with signals injected from an injection point; runs a frequency division under a phase synchronization of the injected signals and inner signals; has an operation frequency decided by an oscillator consuming low power and so is fitted for a circuit using low power; has characteristics of being big in put/output divisors and has a small frequency range for frequency division; and, has an operating frequency not high and a circuit layout quite large.
[0006] A prior art, “High frequency divider circuit”, is proclaimed in Taiwan, which outputs a signal of frequency divided with multi-phases of a cycle according to the input signal. The prior art comprises an n-type serial ring magnifier circuit and a modulation current bias circuit. The modulation current bias circuit produces an alternating current having the same frequency as that of the input signal. The modulation current is injected into the serial ring magnifier circuit; and, a fixed oscillating frequency is obtained from the serial ring magnifier circuit. When the serial ring magnifier achieves a stable oscillating status, an output of the serial ring magnifier outputs a signal of dividing a cycle, and the output frequency is one out of N part of a referring frequency.
[0007] Another prior art, “Frequency Divider”, is pro cl aimed in Taiwan, which comprises a frequency dividing member outputting a first clock and a second clock according to an input clock; a switching member outputting an output clock from the first clock when a switching signal of a first status for input appears, or from the second clock when a switching signal of a second status for output appears; and a switching control member outputting the switching signal of the first status or the second status and outputting the switching signal to the switching member according to the output clock of the switching member.
[0008] Although the above prior arts can divide a frequency, only a single mode can be run while a bigger power supply is consumed and a high speed operation is not achievable. Hence, the prior arts do not fulfill users' requests on actual use.
SUMMARY OF THE INVENTION
[0009] The main purpose of the present invention is to operate a static frequency division and an injection-locking frequency division with the same circuit using low voltage, and to improve frequency dividing speed with lower power consumption.
[0010] To achieve the above purpose, the present invention is a dual-mode frequency divider, comprising a differential input, a pair of latch circuits, an output buffer and a differential output, where each latch circuit comprises a pair of input transistors, a pair of flip-flop transistors and a pair of feedback-receiving transistors; and the differential input further comprises a DC controlling signal device inputting a DC controlling voltage to control a self-oscillating frequency of the latch circuit through a dynamic compensation. Accordingly, a novel dual-mode frequency divider is obtained.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0011] The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in con junction with the accompanying drawings, in which
[0012] FIG. 1 is a structural view showing a preferred embodiment according to the present invention;
[0013] FIG. 2 is a view showing a relationship between in put power and frequency range in a static frequency division according to the preferred embodiment of the present invention;
[0014] FIG. 3 is a view showing a wave of a divided frequency outputted through the static frequency division according to the preferred embodiment of the present invention;
[0015] FIG. 4A is a view showing an inputting of a frequency signal for the static frequency division according to the preferred embodiment of the present invention;
[0016] FIG. 4B is a view showing an inputting of a frequency signal for an injection-locking frequency division according to the preferred embodiment of the present invention;
[0017] FIG. 5 is a view showing a relationship between DC controlling input voltage and DC controlling output voltage according to the preferred embodiment of the present invention;
[0018] FIG. 6 is a view showing first output divisors according to the preferred embodiment of the present invention;
[0019] FIG. 7 is a view showing second output divisors according to the preferred embodiment of the present invention; and
[0020] FIG. 8 is a view showing a comparison between a prior art and the preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] The following description of the preferred embodiment is provided to understand the features and the structures of the present invention.
[0022] Please refer to FIG. 1 , which is a structural view showing a preferred embodiment according to the present invention. As shown in the figure, the present invention is a dual-mode frequency divider, a frequency divider 1 used for a static frequency division and an injection-locking frequency division at the same time, comprising a differential input 11 , a pair of latch circuit 12 , an output buffer 13 and a differential output 14 .
[0023] The differential input 11 inputs a differential alternating-current (AC) signal of a to-be-divided frequency; in the other hand, the differential output 14 outputs a magnified divided differential AC signal; and, the differential input 11 is a gate of a p-type metal-oxide semiconductor (MOS).
[0024] Each latch circuit 12 comprises a pair of input transistors 121 (Mp 1 and Mp 2 , Mp 3 and Mp 4 ), a pair of flip-flop transistors 122 (Mn 1 and Mn 2 , Mn 7 and Mn 8 ) and a pair of feedback-receiving transistors 123 (Mn 5 and Mn 6 , Mn 9 and Mn 10 ), where the input transistor is a p-type MOS to receive an input of a differential AC signal; the flip-flop transistor 122 is an n-type MOS to obtain a first buffer signal from the differential AC signal with an inner switching signal; and the feedback-receiving transistor 123 is an n-type MOS to receive a second buffer signal from another latch circuit 12 . The flip-flop transistor 122 is connected with the feedback-receiving transistor 123 in a parallel way and is stacked in each latch circuit 12 . Hence, with the present invention, the static frequency division function is kept, the voltage supplied is lowered, the power consumed is reduced, and the frequency range for dividing is widened. The above statement concerns about a static frequency division; however, the latch circuit 12 can be regarded as a self-oscillating circuit to output a self-oscillating frequency when an injection-locking frequency division is operated.
[0025] The output buffer 13 is connected with an output of the latch circuit 12 to magnify a signal of a divided frequency obtained through a magnifying circuit selected from an emitter-coup led logic (ECL), a common mode logic (CML), a positive-ECL (PECL) and a low voltage differential signaling (LVDS).
[0026] Please refer to FIG. 2 , which is a view showing a relationship between input power and frequency range in a static frequency division according to the preferred embodiment of the present invention. When the frequency range of the differential AC input signal is enlarged, the power of the differential AC input signal has to be increased too for obtaining a divisor of 2. For example, when a first frequency range 21 of the differential AC in put signal is 8 GHz, the power of the differential AC input signal is −10 dBm; and, when a second frequency range 22 of the differential AC input signal is 15 GHz, the power of the differential AC input signal is 0 dBm.
[0027] Please refer to FIG. 3 , which is a view showing a wave of a divided frequency outputted through the static frequency division according to the preferred embodiment of the present invention. As shown in the figure, when a differential AC signal of 5 GHz frequency is inputted for the static frequency division, a differential output signal of 2.5 GHz frequency is obtained. Therein, a grid in the view represents 200 ps, which means the output signal has a frequency cycle of 400 ps.
[0028] Please refer to FIG. 4A and FIG. 4B , which are views showing input-ends of frequency signals for the static frequency division and an injection-locking frequency division according to the preferred embodiment of the present invention. As shown in the figures, a frequency divider 1 according to the present invention comprises functions used for the static frequency division and an injection-locking frequency division. Therein, a DC controlled signal device 42 is further set at the differential input 41 . When the DC controlled signal device 42 inputs a differential AC signal ‘without’ an extra DC controlled voltage 43 added, the frequency divider 1 operates the static frequency division (as shown in FIG. 4A ) and, when the DC controlled signal device 42 inputs a differential AC signal ‘with’ an extra DC controlled voltage 43 added, the frequency divider 1 operates an injection-locking frequency division (as shown in FIG. 4B ).
[0029] Please refer to FIG. 5 , which is a view showing a relationship between DC controlled input voltage and DC control led output voltage according to the preferred embodiment of the present invention. As shown in the figure, a simulation curve 51 and a measurement curve 52 are shown. Before a differential AC signal is inputted, a DC controlled voltage can be inputted first to obtain a self-oscillating frequency from a latch circuit within. Since the DC controlled voltage adjusts a bias status of the transistors in the latch circuit, the self-oscillating frequency is further adjusted.
[0030] Please refer to FIG. 6 , which is a view showing first output divisors according to the preferred embodiment of the present invention. As shown in the figure, under a fixed self-oscillating frequency of 2.5 GHz, when a first signal of 5 GHz frequency is inputted, an output divisor of 2 is obtained; when a first signal of 10 GHz frequency is inputted, an output divisor of 4 is obtained; when a second signal of 15 GHz frequency is inputted, an output divisor of 6 is obtained; and, when a first signal of 20 GHz frequency is inputted, an output divisor of 8 is obtained. Thus, in an injection-locking frequency division, when a differential AC signal of an even number times of a self-oscillating frequency is inputted and the differential AC input signals and output signals are synchronized, the frequencies of the output signals are the even number part of the input signals and output divisors of even numbers are obtained.
[0031] Please refer to FIG. 7 , which is a view showing second output divisors according to the preferred embodiment of the present invention. As shown in the figure, a first 71 , a second 72 , a third 73 and a fourth 71 curves are shown, each of which has a divisor of 2. In the figure, a self-oscillating frequency of the first curve 71 is adjusted into 1.5 GHz to obtain an input signal of 3 GHz frequency; a self-oscillating frequency of the second curve 72 is adjusted into 2 GHz to obtain an input signal of 4 GHz frequency; a self-oscillating frequency of the third curve 73 is adjusted into 2.5 GHz to obtain an input signal of 5 GHz frequency; and, a self-oscillating frequency of the fourth curve 74 is adjusted into 3 GHz to obtain an in put signal of 6 GHz frequency. Here, by dynamic compensations to self-oscillating frequencies, frequency ranges of the input signals become wider than those in an original injection-locking frequency division according to the present invention. Thus, in an injection-locking frequency division done by the present invention, when the frequency of an differential AC input signal is biased from a self-oscillating frequency and so the frequency is not divided, a circuit providing a DC control led voltage can be used to adjust the self-oscillating frequency through a dynamic compensation so that the self-oscillating frequency becomes an even number part of the frequency of the input signal and the frequency range of the input signal is further widened.
[0032] Please refer to FIG. 8 , which is a view showing a comparison between a prior art and the preferred embodiment of the present invention. As shown in the figure, the voltage supplied for the present invention is lower than that for the prior art; no matter in a static frequency division or in an injection-locking frequency division; power consumption is improved; and, the frequency range of the divided frequency is wider than that in the prior art. Hence, the frequency divider of the present invention has a better frequency operating speed. In addition, the self-oscillating frequency of the present invention can be adjusted in a wider range so that the dynamic frequency range of input signal and the output divisor have wider operation possibilities.
[0033] To sum up, the present invention is a dual-mode frequency divider, where a frequency is divided under a low voltage; a frequency dividing speed is improved; a power consumption is reduced; and a dual-mode operation, containing a static and an injection-locking frequency divisions, is obtained.
[0034] The preferred embodiment herein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.
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The present invention improves a frequency divider circuit so that the frequency divider further obtains a capability of operating an injection-locking frequency division without changing or adding any component; and, the frequency divider operates under low voltage and low power consumption yet in high frequency, where the present invention can be use in related fields of radio frequency and optoelectronic communication.
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CROSS-REFERENCE OF RELATED APPLICATIONS
The present invention claims priority under 35 U.S.C. § 119 of Swiss Patent Application No. 02 606/95-0, filed on Sep. 15, 1995, the disclosure of which is incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
A machine frame for an elevator drive including a drive pulley and a deflecting roller. The deflecting roller may be variably positionable relative to the drive pulley. The position of the deflecting roller, relative to a drive pulley, may determine a spacing of carrying cables between the cage and the counterweight cables. Moreover, the deflecting roller position, with respect to the drive pulley, may influence a looping angle β of the carrying cables on the drive pulley. The spacing between the carrying cables may be determined by a horizontal distance between the axes of the drive pulley and the deflecting roller plus their respective radii. The looping angle β may be varied, within certain limits, by variably raising or lowering the arrangement of the deflecting roller relative to the drive pulley.
The above-noted features may be adapted to the individual requirements of construction and arrangement of the drive pulley and the deflecting roller in a machine frame which may depend on, e.g., cage size and nominal load. Thus, a number of arrangement variations may be contemplated depending on specific elevator models in use. Thus, by a single, substantially universally adaptable construction, the present invention may be utilized in a greater range of elevator systems than those in the prior art.
2. Discussion of Background Information
German published specification No. 1 033 383 discloses a simple drive unit for small-load elevators. This unit includes a drive pulley axle carrying a drive pulley and a belt pulley and arranged somewhat eccentrically at a horizontal profile beam. The belt pulley is arranged in driving connection with a motor including a small belt wheel and fastened while suspended below the profile beam. In addition, a pivotable rocker is arranged on the drive pulley axle and at its other end is provided a deflecting roller. The spacing between the carrying cables leading off can be varied within certain limits by the pivotable rocker which is retained in a desired position by a screwed-on vertical stay. Accordingly, the looping angle β changes constrainedly and uninfluenceably. This may potentially negatively influence driving capability. Further, since the above-noted simple drive unit does not meet the applicable safety regulations, the unit is generally not suitable for passenger elevators without significant construction and accessory device modifications.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to create an elevator drive machine frame for an elevator for transporting people and/or goods which can be easily adapted in situ to certain requirements specifically setting looping angle β and spacing between the carrying cables. Such a machine frame may be adjustably mounted such that the drive pulley and the deflecting roller are coplanar with respect to each other and offset (inclined) with respect to the machine room floor. Further, the deflecting roller may be displaceable relative to the machine frame.
The present invention presents a machine frame that can be arranged in different inclined positions and/or a deflecting roller that can be arranged in different positions.
The different inclined settings of the machine frame, which provides a corresponding change in the looping angle β, may be effected by utilizing pedestals at one or both ends. The pedestals may be variable in height and include semi-circular cut-out portions in the bearing supports for pivotally mounting round ends of the machine frame.
The deflecting roller may be carried by a bearing plate which is laterally displaceable along the machine frame and which can be fixed in any desired position within a adjusting slot. Further, the deflecting roller may be arranged above or below the machine frame.
The present invention may be directed to a machine frame for an elevator drive. The machine frame may include a drive pulley, a deflecting roller, a bearing plate for rotatably mounting the deflecting roller, and a first and second support for supporting the machine frame. The bearing plate may adjustably vary a distance between the drive pulley and the deflecting roller.
According to a further feature of the present invention, the bearing plate may adjustably vary a distance between a cage cable and a counterweight cable.
According to another feature of the present invention, the frame may also include a lateral side member. The bearing plate may be movably affixed to the lateral side member.
According to a further feature of the present invention, the bearing plate may movably position the deflecting roller in a direction parallel to a longitudinal direction of the lateral side member.
According to yet another feature of the present invention, the bearing plate may position the deflecting roller at one of above the lateral side member and below the lateral side member.
According to still another feature of the present invention, the frame may also include a pedestal for one of adjustably raising and lowering at least one of the first and second supports.
According to another feature of the present invention, the pedestal may adjustably vary a looping angle.
According to yet another feature of the present invention, the lateral side member may be positioned parallel to a frame floor.
According to another feature of the present invention, the lateral side member may be positioned at an angle with respect to a frame floor.
A laterally arranged attachment drive may be mounted in operative connection with the drive pulley shaft. Additional accessories may be mounted at the machine frame, as will be described in greater detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of preferred embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
FIG. 1 shows a side elevation of the machine frame in inclined setting;
FIG. 2 shows a plan view of the machine frame; and
FIG. 3 shows a side elevation of the machine frame in horizontal setting.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.
As shown in FIGS. 1 and 2, a machine frame 1 is generally shown. Machine frame 1 may include a pair of lateral side members 6. A first end 6' of each lateral side member 6 may be coupled to a cylindrical support 7. Cylindrical support 7 may extend beyond an exposed lateral face of each lateral side member 6, as shown in FIG. 2. A second end 6" of each lateral side member 6 may be coupled to a support arm 8. As with cylindrical support 7, support arm 8 may extend beyond the exposed lateral face of each lateral side member 6. As shown in FIG. 1, cylindrical support 7 may be substantially tangentially coupled to a bottom of first end 6'. Second end 6" may include a semi-circular cut out portion for coupling the second end 6" with substantially one-half of the outer circumference of support arm 8. Triangular bearing plates 4 may be arranged externally at first end 6' of lateral side members 6. Triangular bearing plates 4 may be arranged to be parallel with and adjacent to the exposed lateral face of each lateral side member 6. Further, each triangular bearing plate projects upwardly from its respective lateral side member 6 and may carry a portion of drive pulley axle 19 which supports a drive pulley 2.
A bearing plate 5 which may be laterally displaceable along lateral side members 6 may be arranged on second end 6" of machine frame 1. Bearing plate 5 may include an upwardly and downwardly extending portion 5' and 5", respectively. Each extending portion 5' and 5" may include a bore 23 for receiving an axle of a deflection roller 3. As shown in FIG. 1, the axle of deflection roller 3 is coupled to bore 23 in downwardly extending portion 5", however, the ordinarily skilled artisan will recognize that other advantages may be realized by coupling the axle of deflection roller 3 to bore 23 of upwardly extending portion 5', as discussed below. Within each side member 6 is a longitudinally extending adjusting slot 10. Screws 11 may be utilized to fix the position of bearing plate 5. Further, screws 11 may be loosened to enable adjustment of the position of bearing plate 5 along a longitudinal axis of lateral side member 6 within the range defined by adjusting slot 10. Bearing plate 5 may also include abutment strips 21 and 22 which abut a top and bottom edge of lateral side member 6 in order to prevent bearing plates 5 from dropping out of machine frame 1 when screws 11 are loosened. Thus, abutment strips 21, 22 form guides for slideably adjusting the position of bearing plates 5 longitudinally along the length of lateral side member 6.
Recessed bearing supports 9 may be positioned near the first and second end 6' and 6" of lateral side member 6 to support machine frame 1. Each recessed bearing support 9 may include a semicircular cut-out for receiving a respective end of one of cylindrical support 7 and support arm 8. The recessed bearing support positioned below cylindrical support 7 may be positioned upon a pedestal 12 and the recessed bearing support positioned below support arm 8 may be positioned on machine floor 13. Thus, a predetermined difference is maintained between the distance from cylindrical support 7 to machine room floor 13 and the distance from support arm 8 to machine room floor 13. In the situation illustrated in FIG. 1, the predetermined difference is equal to the height of pedestal 12.
Elevator cables 17 may be characterized as cage cables 15 and counterweight cables 16. Drive pulley 2 may be looped around, e.g., one or twice, etc., by elevator cables 17, an end running vertically downward from drive pulley 2 to an elevator cage (not shown) being known as the cage cable 15. The elevator cables 17 may also run obliquely downward from drive pulley 2 to be guided over deflecting roller 3. Deflection roller 3 may be looped around, e.g., one or twice, etc., by elevator cables 17 prior to running vertically downward from deflection roller 3 to an elevator counterweight (not shown) are known as the counterweight cables 16. As shown in FIG. 1, a looping angle β may be formed on drive pulley 2 at approximately 155°.
Cage cables 15 and counterweight cables 16 may be directed into an elevator shaft through an opening 14 in machine room floor 13. A spacing between cage cables 15 and counterweight cables 16 may be denoted by distance a. An attachment drive 18 may be coupled to the machine frame, as shown. Attachment drive 18 may include mechanical elements of a usual elevator drive, such as a motor, tacho-dynamo, brake, reduction gear, fixed coupling with the drive pulley 2 and torque stay (not shown).
FIG. 2 shows the machine frame of the present invention in plan view. Attachment drive 18 may be arranged at an upper side thereof. However, depending upon requirement, and prevailing space conditions, attachment drive 18 may also be provided at the other side. Bearing supports 9 may each be arranged below respective ends of cylindrical support 7 and support arm 8 to ensure a widest possible support of the machine frame 1. The bearing point below attachment drive 18 may be drawn up somewhat further for the purpose of optimum support and stability, which is indicated by dashed lines.
FIG. 3 shows machine frame 1 according to an alternative arrangement in a horizontal position with respect to machine room floor 13. That is, lateral side members 6 are positioned substantially parallel to machine room floor 13. This change in position of machine frame 1 may be effected through different heights of pedestals 12 (FIG. 1) and 20 and utilizing the semicircular cut-outs of recessed bearing supports 9 as a slide bearing for support arms 7 and 8. Further, the semicircular cut-outs in recessed bearing supports 9 may enable a pivotable bearing of first and second ends 6' and 6" of the machine frame. In the situation illustrated in FIG. 3, a single looping angle β of 120° may be formed at drive pulley 2 by raising second end 6" with respect to first end 6'. By way of comparison with the inclined position depicted in FIG. 1, horizontal positioning of the machine frame 1 may result in a reduction in the looping angle β by approximately 35°. Alternatively, the looping angle β could be increased by approximately 35° by positioning machine frame 1 in an inclined position, as shown in FIG. 1.
However, not only may looping angle β be varied by adjusting the relative inclination of the machine frame 1 with respect to machine room floor 13, but also distance a between cage cables 15 and counterweight cables 16 may be varied. In addition to adjusting the relative inclination of machine frame 1, the distance a and the looping angle β may be adjustably varied by adjusting the position of bearing plate 5 along the length of lateral side number 6 and within adjusting slot 10.
Another alternative manner for varying distance a and/or looping angle β makes use of the upper portion 5' of bearing plate 5. As shown generally in FIGS. 1 and 3, the axle of deflecting roller 3 is mounted in bore 23 of lower portion 5". However, bearing plate 5 may be symmetrically shaped. Thus, the axle of deflecting roller 3 may alternatively be mounted in bore 23 of upper portion 5', as shown in phantom lines in FIG. 3.
Therefore, the two characteristic magnitudes of looping angle β and cable spacing distance a may be varied within certain defined limits by each of the three above-mentioned alternative manners of adjustment. Accordingly, a single machine frame structure may be utilized in a wide field of applications, which results in correspondingly greater production runs and reduced unit costs.
The construction of machine frame 1, according to the present invention, is not intended to be limited or restricted to the construction details shown above. Thus, for example, upper portion 5' with bore 23 may be omitted in the displaceable bearing plate 5. However, bearing plate 5, with only one lobe, offers the same positioning variability as the double lobe bearing plate, except that to change the lower portion to an upper portion the single lobe must be physically removed (or loosened) and reattached to (or rotated with respect to) the lateral side wall 6.
Further, pedestals 12 and/or 20 may include fixed height stackable pedestal plates. The pedestal plates may be immovable relative to each other through shape-locking and may be assembled in a modular manner in accordance with the specific height requirements necessary.
According to the present invention, different accessory apparatuses, e.g., a speed limiter, may be coupled to machine frame 1, e.g., with mechanical connecting parts and assembly holes positioned at suitable places on lateral side members 6.
The specific construction of machine frame 1 may also accommodate an electromechanical or hydraulic cable brake as a second brake. The electromechanical or hydraulic cable brake may be arranged to bridge across the two lateral side members 6.
It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the invention has been described with reference to a preferred embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the invention in its aspects. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein; rather, the invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.
LIST OF DESIGNATED ELEMENTS
1 Machine frame
2 Drive pulley
3 Deflector roller
4 Bearing plate
5 Displaceable bearing plate
5' Upper portion
5" Lower portion
6 Lateral side member
6' First end
6" Second end
7 Cylindrical support
8 support arm
9 Recessed bearing support
10 Adjusting slot
11 Screws
12 Pedestal
13 Machine room floor
14 Opening
15 Cage cables
16 Counterweight cables
17 Elevator cables
18 Attachment drive
19 Drive pulley shaft
20 Pedestal
21 Upper abutment strip
22 Lower abutment strip
23 Bearing bore
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A machine frame with two side members at its ends comprises support arms, which are pivotably mounted in semi-circular cut-out bearing supports. The bearing supports may be arranged on differently high pedestals, which may result in different inclined positions for the machine frame with respect to a machine room floor. The inclined position may provide for a variable looping angle β at the drive pulley and variable cable spacing between the cage cables and the counterweight cables. Furthermore, the deflecting roller may be mounted in laterally displaceable bearing plates. The deflecting roller may be inserted above or below a pair of side members. The position of the deflecting roller with respect to the side members may also have an effect on the looping angle β and the cable spacing. The combination of these adjustment possibilities enables the substantially universally adaptability of the machine frame to different elevator systems and applications.
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TECHNICAL FIELD
The present invention is generally related to gas burners and, more particularly, is related to apparatuses and methods for igniting gas burners.
BACKGROUND OF THE INVENTION
Many cooking and other devices employ burners that use combustible gas as the source of heat energy for the cooking of food products. In these devices, efforts have been made to simplify the igniting of the gas burners. For example, ignition mechanisms have been designed which eliminate the need for manual ignition using matches or butane lighters. Typically, these prior art ignition mechanisms employ a spark generator, or a source of high voltage, that is connected to a single electrode is grounded through a metal frame or support in the device. The arc then ignites the gas emanating from the burner.
Although the prior art ignition mechanisms have generally worked well, the design of these mechanisms leaves them susceptible to failure in certain circumstances. For example, the electrode, or the wire connecting the electrode to the spark generator, can be inadvertently shorted to ground, thus preventing a spark from being generated between the electrode and the burner. Such a short can be caused by a variety of reasons, such as the excessive dripping and buildup of foodstuffs on the ignition mechanism. In such circumstances a potentially dangerous build-up of unignited gas could result. Additionally, corrosion may occur at assembly points in the appliance, thus shorting the ground and reducing the opportunity for an efficacious spark.
Alternative ignition mechanisms include an insulated electrode that is housed in a collector box. Gas from the burner flows into the collector box and out an opening in a side wall of the collector box. Typically the insulated electrode is the same size as the opening through which it protrudes, completely filling the opening. A dimple or protrusion stamped on a side wall of the collector box acts as a grounding electrode. Thus, the spark from the insulated electrode must be large enough to jump into the stream of gas from the burner toward the grounding electrode. If the spark generated is not large enough, is weak, or if it is not in contact with a proper concentration of gas, then the gas, and consequently the burner, do not ignite.
In addition, the collector box may be mounted to a grill casting instead of a burner, or may be screwed onto the burner via various fastening means. The attachment of the collector box to the grill parts may be problematic in that traditional fastening means tend to be cumbersome, and make the ignition system difficult to assemble. The attachments have generally not been universal in nature, with different fastening means required for attachment of the collector box to different grill parts, thus decreasing their usefulness. Because the traditional means of attaching the collector box to the grill or burner is cumbersome, there is an increased risk of erroneously assembling the collector box.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.
BRIEF DESCRIPTION OF THE DRAWINGS
The disclosed ignition system can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the ignition system. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIG. 1 is an exploded perspective view of an embodiment of the disclosed gas burner ignition system.
FIG. 2 is a partial exploded cross-sectional view of an embodiment the gas burner ignition system of FIG. 1 in a barbecue grill casting environment, showing the burner before mating with the collector box.
FIG. 3 is a partial cross-sectional view of the gas burner ignition system of FIG. 2, showing the assembled burner and collector box.
FIG. 4 is a perspective view of the bottom half of a collector box and an insulated electrode of the gas burner ignition system of FIG. 1 .
SUMMARY OF THE INVENTION
The disclosed gas burner ignition system includes a spark generator, the spark generator including a first electrical terminal connected to an insulated electrode via an electrically conductive lead, and a second electrical terminal connected to a ground; an insulated electrode connected to the spark generator via a wire lead; and a collector box. The collector box includes, in an exemplary embodiment, an aperture disposed within the bottom half, the aperture being configured to receive the insulated electrode substantially within the center of the aperture and to allow gas from a gas burner to exit the aperture around the insulated electrode.
The disclosed gas burner ignition system may be incorporated into a cooking device such as a barbecue grill. In such an exemplary embodiment of a barbecue grill, the grill includes a cooking surface, a source of liquid propane gas, a gas burner, and the gas burner ignition system.
DETAILED DESCRIPTION
One way to improve the ignition ability of a gas burner ignition system is to position an insulated electrode in a collector box directly in the path through which gas must flow from a burner. Additionally, placing a grounding electrode also in the path of the gas also helps ensure that the spark from the insulated electrode to the grounding electrode will ignite the stream of gas in the disclosed gas burner ignition system. In this regard, reference is now made to the figures. More specifically, referring now to FIG. 1, a representative gas burner ignition system 100 will be described in greater detail that solves deficiencies in prior art ignition systems.
The ignition system 100 includes a spark generator 1 , an insulated electrode 3 , and a collector box 8 . The spark generator 1 has two electrical terminals 2 , one for an insulated wire lead 5 for the insulated electrode 3 , and one for a ground wire 7 . It should be noted that while reference is made throughout the specification to an “insulated electrode 3 ” and “insulated wire lead 5 ” that leads to the insulated electrode 3 , that the ground wire 7 may, in some embodiments, be insulated as well. For instance, it may be particularly desirable to insulate the ground wire 7 when using the ignition system 100 to ignite more than one burner, e.g., a side burner.
The insulated electrode 3 includes a ceramic insulator 4 , and a mounting bracket 6 attached thereto. The end of the ground wire 7 is, in one embodiment, a standard electrical terminal, such as that having a shape of an elongated “C.” The collector box 8 includes a top half 9 , a bottom half 10 , a first fastening device 11 and an optional second fastening device 12 , thereby forming an enclosure. The first fastening device 11 may be for example, a carriage bolt, or any other fastening device capable of attaching the mounting bracket 6 to the collector box 8 . The second fastening device 12 may be any device that helps secure the mounting bracket 6 to the collector box 8 , for example, a wing nut as shown. Both the top half 9 and the bottom half 10 of the collector box 8 include mounting flanges 15 and side walls 19 . In one embodiment, flanges 15 may be, for example, but are not limited to, approximately one-fourth (¼) to approximately three-eighths (⅜) inch wide. Bottom half 10 of the collector box 8 further includes a tab 13 disposed, for example as shown in FIG. 2, between two flanges 15 that is, in a preferred embodiment, but not limited to, approximately three-thirty-secondths ({fraction (3/32)}) to approximately one-eight (⅛) inch wide.
The ignition system 100 may be assembled in the following manner. The ground wire 7 is attached to the tab 13 on the bottom half 10 of the collector box 8 . In an exemplary embodiment, the tab 13 is thin enough to be bent back manually by a user. By way of example, the tab 13 may be made of twenty-gauge stainless steel, and formed out of the same piece of metal as the bottom half 10 of the collector box 8 .
The electrode 3 is then assembled to the bottom half 10 of the collector box 8 using the fastening device 11 . The tab 13 is bent over the end of the fastening device 11 to aid in retaining the fastening device 11 , and to aid in retaining the electrode 7 to the bottom half 10 of the collector box 8 . The tab 13 may be bent over an end of the fastening device 11 at, for example, a 30-degree angle.
Shown in FIG. 2 is an exemplary gas burner ignition system 100 in an exemplary environment of a barbecue grill casting 22 , before mating of the burner 16 with the collector box 8 . As depicted in FIG. 2, the top half 9 of the collector box 8 is placed on the bottom half 10 of the collector box 8 and secured. The top half 9 and the bottom half 10 are secured together either before or after mating the collector box 8 with the burner 16 . The top half 9 and the bottom half 10 can be arranged to move pivotally with respect to each other, for example, by hinges. Alternatively, the top half 9 and the bottom half 10 may be secured together by threadedly fastening the second fastening device 12 to the first fastening device 11 , such as, for example, with a screw and wing nut as shown.
The side walls 19 of the top half 9 may be disposed within the side walls 19 of the bottom half 10 when the top half 9 and the bottom half 10 are connected. The top half 9 of the collector box 8 may include an optional pivoting connection 18 that aids in alignment of the top half 9 and the bottom half 10 . Thus, in one embodiment, the top half 9 and the bottom half 10 form a clamshell-type design such that the fastening device 11 helps secure the top half 9 and the bottom half 10 in place. In this manner, when the second fastening device 12 is tightened, a gap 14 is decreased between mounting flanges 15 of the top half 9 and the bottom half 10 . Conversely, when the second fastening device 12 is loosened over the first fastening device 11 , the gap 14 increases. In this manner, the gap 14 is adjusted such that a hem, or lip, 20 of a burner 16 may slide in between flanges 15 , mating the collector box 8 and the burner 16 .
As shown in FIG. 3, when the hem 20 of the burner 16 is disposed between flanges 15 of the top half 9 and the bottom half 10 , the flanges 15 are tightened until the flanges 15 clamp down and secure burner 16 , for example, by tightening the second fastening device 12 .
If the gas burner 16 is disposed in a cooking device, the insulated wire lead 5 and the ground wire 7 may also be placed in the cooking device. For instance, in a cooking device such as a barbecue grill (not shown), the wire lead 5 and the ground wire 7 are passed through the grill bottom casting 22 and through a spark generator mounting hole in a control panel of the cooking device. The insulated wire lead 5 of the electrode 3 is attached to the electrical terminal 2 of the spark generator 1 . The ground wire 7 is attached to a second electrical terminal 2 of a spark generator 1 . The spark generator 1 is then attached to the control panel of the cooking device. It should be noted that although the insulated wire lead 5 typically is attached to the very end of the spark generator 1 , as shown in FIG. 1, it does not matter which wire 5 or 7 is attached to either of the terminals 2 of the spark generator 1 . Additionally, the spark generator 1 is not limited to the exact configuration depicted in FIG. 1, but may be, for example, an electronic spark generator.
The disclosed ignition system works in the following manner. Gas from the burner 16 flows into the collector box 8 and out an aperture 21 (depicted in FIGS. 1 and 4) in the bottom half 10 of the collector box 8 . The aperture 21 may be circular in shape, for example. Optionally, at least one grounding electrode 17 protrudes from an edge of the aperture 21 . The insulated electrode 3 is positioned substantially in the center of the aperture 21 . The aperture 21 is configured to be larger in size than the insulated electrode 3 disposed therein, thus allowing gas to exit the aperture 21 around the electrode 3 . Upon triggering the spark generator 1 , a spark is produced between the insulated electrode 3 and either the edge of the aperture 21 , or optionally, one of the grounding electrodes 17 . The grounding electrode 17 is positioned so that gas exiting the collector box 8 through the aperture 21 will pass between the insulated electrode 3 and the grounding electrode 17 .
The grounding electrode 17 may be bent up relative to the bottom half 10 , bent down relative to the bottom half 10 , and substantially planar with a bottom surface of the bottom half 10 . Optionally, as shown more clearly in FIG. 4, the grounding electrode 17 may be bent in a twisted fashion like a fan blade in order to swirl the gas as it exits the collector box 8 through the aperture 21 , creating a vortex-type formation with the gas. The vortex created by the swirling motion will tend to concentrate the gas around the center of the aperture 21 . Additionally, the vortex-type formation serves to swirl the gas with air in the environment, causing a more efficient burning of the spark. Because the insulated electrode 3 is located in the aperture 21 , more reliable gas ignitions result.
As noted with respect to FIGS. 2 and 3, the gas burner ignition system may be used in a barbecue grill. A cross-section of the grill casting 22 is depicted in FIG. 2 . The grill may also include, in addition to the gas burner ignition system, a cooking surface, a source of liquid propane gas, and a gas burner. The disclosed grill is user-friendly in that the gas burner lights more efficiently and consistently than has been heretofore accomplished in the art.
It should be emphasized that the above-described embodiments of the disclosed gas burner ignition systems are merely possible examples of implementations, and are merely set forth for a clear understanding of the described principles. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of this disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and the following claims.
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A collector box for a gas burner ignition system is disclosed, the collector box including a top half; a bottom half; an aperture disposed within the bottom half, the aperture being configured to receive an insulated electrode substantially within the center of the aperture and to allow gas from a gas burner to exit the aperture around the insulated electrode; and a grounding electrode protruding from an edge of the third aperture, where a spark may be produced between the insulated electrode and the grounding electrode. Also disclosed are gas burner ignition systems that include the above-described collector box, as well as a spark generator and an insulated electrode. The gas burner ignition system may be used in, for example, cooking devices such as barbecue grills.
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FIELD OF THE INVENTION
The present invention relates generally to hard sintered compacts for tools employing cubic boron nitrides (hereinafter referred to as "cBN") and, more particularly, to a hard sintered compact for tools having enhanced strength and wear resistance with improvements of a binder.
DESCRIPTION OF THE BACKGROUND ART
cBN is the hardest material next to diamond, and a sintered compact of cBN is employed for various cutting tools.
As one example of cBN sintered compacts suitable for cutting tools, Japanese Patent Publication No. 57-3631 (corresponding U.S. Pat. No. 4,334,928) discloses a hard sintered compact for tools, containing 80-40% by vol. of cBN and the remaining proportion of carbide, nitride, boride and silicide of elements selected from groups of the IVa, Va and VIa periodic table, mixtures thereof or counter solid solution compounds as principal components. These compounds constitute a continuous bound phase in the texture of the sintered compact. This sintered compact exhibits high performance in general as a material for cutting tools; however, it has a disadvantage that the cutting edge of the cutting tool is liable to be damaged due to insufficient strength and abrasion of the cutting edge when subjected to a considerably strong impact, for example, in the application for a continuous cutting of a highly hardened steel.
An improved hard sintered compact for tools, in which the strength and wear resistance of a cutting edge made of the sintered compact is improved in order to eliminate the damage of the cutting edge, is disclosed in Japanese Patent Laying-Open No. 62-228450. In this sintered compact, a binder includes 25-50% by wt. of Al, a compound containing Ti such as carbide of Ti, and 4-40% by wt. of W contained in the compound containing Ti or contained as WC. These components react with cBN in sintering, to produce aluminum boride, titanium boride and the like, which serve to firmly bond the binder and cBN or another binder.
U.S. Pat. No. 4,911,756 discloses a hard sintered compact for tools, including 50-75% by vol. of cBN and 25-50% by vol. of a binder containing 20-50% by wt. of aluminum, carbon nitride titanium and the like and 4-40% by wt. of tungsten.
Even the sintered compacts disclosed in the above-described Japanese Patent Publication No. 57-3631, Japanese Patent Laying-Open No. 62-228450 and U.S. Pat. No. 4,911,756 have, however, the following disadvantages when used for tools for cutting a cast iron. In cutting of a graphite cast iron and fast cutting of a gray cast iron, for example, abrasion of the cutting edge abruptly proceeds, so that the life of the cutting edge is shortened. Further, crater abrasion occurs in the cutting edge, so that the cutting edge is damaged. These problems still remain unsolved.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a hard sintered compact for tools having excellent strength and wear resistance and exhibiting an excellent cutting performance even for a cast iron.
In order to accomplish the above object, a hard sintered compact for tools according to the present invention is a sintered compact obtained by super-high pressure sintering of 45-75% by vol. of cBN powder and the remaining proportion being formed as a binder from a binder powder. The binder contains 5-25% by wt. of A; and the remaining proportion of at least one species of compounds represented by (Hf l-z M z ) C, where M denotes elements of groups IVa, Va and VIa other than Hf in the periodic table, and 0≦z≦0.3 is satisfied. In this specification the designation of groups IVa, Va, and VIa of the periodic table corresponds to the conventional U.S. designation of groups IVb, Vb, and VIb in the periodic table.
In accordance with the present invention, since the binder includes 5-25% by wt. of Al and the remaining proportion of (Hf l-z M z ) C compound as shown in the foregoing composition, these components react with cBN in the sintering under high-temperature and high-pressure, to produce aluminum boride (AlB 2 ), aluminum nitride (AlN), hafnium boride (HfB 2 ) or titanium boride (TiB 2 ). Alternatively, Al and the (Hf l-z M z ) C compound react with each other. These reaction products firmly couple cBN having an excellent resisting property to abrasion and the binder, or the binder and another binder. This results in a sintered compact having excellent strength and excellent wear resistance.
It is confirmed by X-ray diffraction that a slight amount of Al exist also as aluminum oxide in the sintered compact; however, the existing Al does not affect the action and effects of the present invention.
The (Hf l-z M z ) C compound such as HfC and a reaction product such as HfB 2 can provide sufficient resisting properties to heat and oxidation when the temperature of the cutting edge becomes higher by cutting of a cast iron or the like. These compounds and reaction products have excellent wear resistance and excellent strength under high temperature and can enhance the strength, wear resistance, heat resisting properties, etc. of the binder per se.
When the content of Al in the binder is less than 5% by wt., the retention of cBN by the binder decreases due to an insufficient reaction between Al and cBN. When the Al content exceeds 25% by wt., AlB 2 or the like increases, and the bonding strength between cBN and the binder increases. The relative content of the (Hf l-z M z ) C compound such as HfC having superior wear resistance to that of AlB 2 or the like, however, decreases. Accordingly, the hardness of the binder per se decreases, and hence the sintered compact fails to obtain sufficient wear resistance for the cast iron cutting and the like.
As compounds represented by the formula (Hf l-z M z ) C in the binder, there are many kinds of carbides containing Ti, Mo, W, etc. together with Hf in the case of 0<z as well as HfC in the case of z=0. Carbide containing Ti or W is especially preferable because it serves to reduce the wear resistance and the strength of the binder and to exhibit good characteristics. When z exceeds 0.3 in the foregoing formula, however, the content of HfC having relatively excellent wear resistance decreases. Thus, z is set to 0.3 or less.
Further, adding at least one species of iron group elements in the binder causes the strength and hardness of the binder to further increase, resulting in further improvements of the characteristics of the sintered compact. This is because an enhanced wetness between the iron group elements and borides such as HfB 2 and AlB 2 causes the binder to firmly couple or bond the borides.
When the amount of cBN in the sintered compact is less than 45% by vol., the strength and hardness of the sintered compact decreases. In addition, as the number of binders relatively increases, mechanical abrasion advances rapidly by, for example, a hard graphite contained in a cast iron and hard portions of a pearlite base in matrix, a base subjected to austempering and the like. Also, a crack is liable to occur due to an applied impact. When the amount of cBN in the sintered compact exceeds 75% by vol., cBN makes contact with another cBN. Thus, in the case of a strong member to be cut or an interrupted cutting in which high pressure is applied to a cutting edge, a crack is produced in contact portion between particles, and the number of binders relatively decreases. This results in a reduction in bonding strength between the binders and cBN and thus a reduction in strength of the sintered compact.
In abrasion of a general cBN sintered compact, it is considered that since cBN has excellent wear resistance, the binder is abraded first, whereby cBN drops out of the compact. Therefore, the particle size of cBN is preferably controlled as follows in order to make uniform the texture of the compact and to inhibit a premature abrasion of the binder. The average particle size of cBN is preferably smaller. When the particle size exceeds 4 μm in particular, a binder portion becomes larger and abraded with priority. Accordingly, the average particle size of cBN is preferably 4 μm or less. More preferably, if the particle size of cBN is controlled so that cBN of 1 μm or less in particle size may be 35-80% by wt. and that cBN of 3-6 μm in grain size may be 20-65% by wt., smaller cBN particles fill among larger cBN particles, so that the microstructure becomes homogeneous.
It is preferable in view of enhancement of wear resistance to employ micro binder powder having an average size smaller than 1/3 that of cBN because such micro binder powder advances uniform distribution of the binders.
According to another aspect, a hard sintered compact for tools in accordance with the present invention is a sintered compact obtained by super-high pressure sintering of 45-75% by vol. of cubic boron nitride powder and contains the remaining proportion of binder powder. The binder contains 4-20% by wt. of Al and 5-20% by wt. of Hf and contains the remaining proportion of HfC and a compound represented by (Ti l-x M x ) C z , (where M denotes elements of IVa, Va and VIa groups except for Hf in the periodic table; and 0≦x≦0.15, 0.55≦z≦0.9 are satisfied in the range of volume ratio 9:1-1:2.
With this composition, since the binder contains 4-20% by wt. of Al and 5-20% by wt. of Hf, and HfC and the above (Ti l-x M x ) C z compound, these components react with cBN in sintering under high-temperature high-pressure, to produce aluminum boride (AlB 2 ), aluminum nitride (AlN), and hafnium boride (HfB 2 ) or titanium boride (TiB 2 ). Further, Al reacts with HfC or the (Ti l-x M x ) C z compound. These reaction products firmly couple cBN having excellent wear resistance and the binder, or alternatively the binders. Therefore, a sintered compact superior in its strength and wear resistance can be obtained. The HfC and the (Ti l-x M x ) C z compound along with those reaction products can provide sufficient resistance to heat and oxidation when the temperature of the cutting edge becomes higher in cast iron cutting or the like, as has been already described. Since those reaction products and compound have excellent wear resistance and excellent strength under high temperature, the strength, wear resistance, heat resistance, etc. of the binder per se can be enhanced.
When the content of Al in the binder is less than 4% by wt., the reaction between Al and cBN becomes insufficient. When the content of Hf is less than 5% by wt., the reaction between Hf and Al or (Ti l-x M x ) C z becomes insufficient. In both cases, the retention of cBN by the binder decreases. Conversely, when the content of Al or Hf exceeds 20% by wt., a larger amount of AlB 2 , HfB 2 or the like is produced, resulting in increased bonding strength of cBN and the binder. Since the relative content of HfC and the (Ti l-x M x ) C z compound having superior wear resistance to that of AlB 2 and HfB 2 decreases, however, the hardness of the binder per se and the wear resistance of the sintered compact decrease.
The reason why the volume ratio of HfC to the (Ti l-x M x ) C z compound in the binder is limited in the volume range of 9:1-1:2 is given below. First, when the amount of HfC relatively increases exceeding 9:1, Al in the binder still exceeds in amount even if reacting with HfC or the (Ti l-x M x ) C z compound. Thus, the excess Al remains unreacting, to degrade the wear resistance. Conversely, when the (Ti l-x M x ) C z compound relatively increases in amount exceeding 1:2, the reaction between HfC and the (Ti l-x M x ) C z compound becomes supersaturation, and thus Hf remains as a metal component, to degrade the wear resistance.
In the formula (Ti l-x M x ) C z , x=0, i.e., the state where M is not included may be satisfied. When x exceeds 0.15, the amount of TiC having excellent resistance to heat and abrasion relatively decreases, and the wear resistance and the strength under high temperature also decrease, resulting in an inadequate material for tools. The reason why the relation 0.55≦z≦0.9 is satisfied is that when z is less than 0.55, the amount of free Ti increases, and the strength and hardness of the binder per se decreases, whereas when z exceeds 0.9, the free Ti becomes insufficient in amount, and the bonding force of the binder decreases. If W is employed as M, the wear resistance and strength of the binder improves and exhibits good characteristics.
The reason why at least one species of iron group elements is added in the binder and why the amount of cBN in the sintered compact is set to 45-75% by vol. are given in the foregoing description.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiment 1
Carbide containing Hf and Al powder are ground and mixed by employing a superhard alloy pot and bowl, to produce binder powder of 0.9 μm or less in average particle size having such composition as shown in Table 1 below. The produced binder powder and cBN powder of 2.5-4 μm in average particle size are mixed in the volume ratio of 42:58. The mixed powder are then put in a Mo container, heated in a vacuum furnace at 10 -4 torr, 1000° C. for 20 minutes and then deaired. Thereafter, the resultant powder is sintered under the pressure of 55Kb, at the temperature of 1400° C. for 25 minutes.
When each of the resulting sintered compacts is identified by X-ray diffraction, the peak of cBN, that of the carbide containing Hf and those of HfB 2 , AlB 2 and AlN are confirmed with respect to all the sintered compacts. The peaks of carbides including Ti, Mo and W other than Hf are also confirmed from samples. In addition, when the texture of the sintered compacts is observed by a scanning electron microscope, it is confirmed that cBN particles are mutually bonded by binders.
Furthermore, each sintered compact is processed to be an insert for cutting and undergoes a cutting test of a nodular cast iron FCD 45 member (hardness H B =200). The test is carried out on conditions of 280 m/min in cutting speed, 0.25 mm in depth of cut, 0.22 mm/rev in feed rate and 20 minutes in cutting time by dry process. Table 1 shows the result of the test.
TABLE 1______________________________________ Binder Composition Abrasion width ofSample No. (% by wt.) Relief Plane (mm)______________________________________1 HfC:95, Al:5 0.0592 HfC:90, Al:10 0.0423 (Hf.sub.0.7 Ti.sub.0.3)C:80, Al:20 0.0554 HfC:75, Al:25 0.0725 (Hf.sub.0.95 Mo.sub.0.05)C:88, Al:12 0.0476 (Hf.sub.0.95 Mo.sub.0.05)C:92, Al:8 0.0557 (Hf.sub.0.9 Ti.sub.0.1)C:85, Al:15 0.037 8* HfC:97, Al 3 0.098 9* HfC:72, Al:28 0.11010* (Hf.sub.0.65 Mo.sub.0.35)C:75, Al:25 0.12711* (Hf.sub.0.9 Ti.sub.0.1)C:70, Al:30 0.15412* (Hf.sub.0.6 V.sub.0.4)C:90, Al:10 0.108______________________________________
Embodiment 2
HFC powder of 89% by wt. and Al powder of 11% by wt. are ground and mixed in the same manner as embodiment 1, to produce binder powder having average particle size shown in Table 2 below. The produced binder powder is mixed with cBN powder shown in table 2, deaired as in embodiment 1 and then sintered under the pressure of 45 Kb, at the temperature of 1300° C. for 20 minutes, thereby to obtain sintered compacts.
Each of the sintered compacts is processed to be an insert for cutting. Then, the end surface of a cylinder of a ductile cast iron FCD 70 member (hardness H B =290) is cut by dry process at 180 m/min in cutting speed, 0.2 mm in depth of cut and 0.17 mm/rev in feed rate. The cutting time during which the abrasion width of a relief plane reaches 0.2 mm is measured. The result of the test is shown in Table 2.
TABLE 2______________________________________AverageParticle Distribution AverageSize of Amount of cBN Particle CuttingSam- Binder of cBN Particle Size Size of Timeple (μm) (vol %) (μm:%) cBN (μm) (min)______________________________________13 0.3 45 0-1:35 3.6 34 2-4:45 4-8:2014 0.4 55 0-1:40 2.3 40 1-2:25 3-6:3515 0.5 65 0-1:40 3.8 38 3-6:6016 0.2 75 0-1:75 2.2 33 3-6:2517 0.4 60 0-1:45 3.1 45 3-6:5518 0.4 58 0-2:80 2.1 58 3-6:2019 0.3 50 0-1:40 1.9 51 1-2:30 3-6:3020 0.3 70 0-2:65 2.8 47 2-4:3521 1.5 65 0-1:32 4.0 27 3-6:6822 1.4 70 3-6:100 4.1 2423 2.2 65 4-8:100 6.0 21 24* 0.2 43 0-2:58 2.7 Damaged 4-8:42 in 6 min. 25* 0.4 78 0-1:50 3.0 7 4-8:50 26* 1.3 40 2-4:100 3.1 Damaged in 3 min.______________________________________
Embodiment 3
HfC powder, carbide powder containing Ti, Hf powder and Al powder are all ground and mixed together employing a superhard alloy pot and bowl, to produce binder powder of 0.8 μm or less in average particle size having a composition shown in Table 3 below. The produced binder powder and cBN powder of 2.5-4 μm in average particle size are mixed in the volume ratio of 50:50. The mixed powder is put in a Mo container, heated in a vacuum furnace at 10 -4 torr, 100° C. for 20 minutes and then deaired. The resultant powder is then sintered under the pressure of 55 Kb and at the temperature of 1400° C. for 30 minutes.
TABLE 3______________________________________Sample No. Binder Composition (% by wt.)______________________________________27 HfC:87, TiC.sub.0.6 :4, Al:4, Hf:528 HfC:64, (Ti.sub.0.9 W.sub.0.1)C.sub.0.55 :6, Al:10 Hf:2029 HfC:72, TiC.sub.0.9 :14, Al:7, Hf:730 HfC:46, TiC.sub.0.7 :36, Al:12, Hf:631 HfC:41.5, (Ti.sub.0.95 Mo.sub.0.05) C.sub.0.8 :32.5 Al:20, Hf:632 HfC:75, TiC.sub.0.85 :6, Al:9, Hf:1033 HfC:63.6, TiC.sub.0.75 :12.4, Al:15, Hf:934 HfC:75, (Ti.sub.0.95 W.sub.0.05)C.sub.0.6 :10, Al:9 Hf:6 35* HfC:89.6, TiC.sub.0.7 :8.4, Al:2 36* HfC:67.9, (Ti.sub.0.95 W.sub.0.05)C.sub.0.8 :3.1 Al:22, Hf:7 37* HfC:32, TiC.sub.0.89 :38, Al:10, Hf:20 38* HfC:72.2, TiC.sub.0.55 :2.8, Al:20, Hf:5 39* HfC:18.4, (Ti.sub.0.95 Mo.sub.0.05)C.sub.0.7 :71.6 Al:5, Hf:5 40* HfC:45, TiC.sub.0.4 :35, Al:10, Hf:10 41* HfC:41.5, TiC.sub.0.95 :32.5, Al:4, Hf:22______________________________________
Each of the resultant sintered compacts is identified by X-ray diffraction. The peak of cBN, that of carbide including Hf, and those of HfB 2 , AlB 2 , AlN and TiB 2 are confirmed with respect to all the sintered compacts. The peaks of carbides of Mo, W other than Hf are also confirmed from samples. When the texture of the sintered compacts is observed by a scanning electron microscope, it is confirmed that cBN micro particles are mutually coupled by binders.
In addition, each sintered compact is processed to be a insert for cutting and undergoes a cutting test of a nodular graphite cast iron FCD 45 member (hardness H B =200). This test is carried out on such conditions as 300 m/min in cutting speed, 0.3 mm in depth of cut, 0.2 mm/rev in feed rate and 20 min. in cutting time by dry process. The result of the test is shown in Table 4 below.
TABLE 4______________________________________ Abrasion Width Abrasion WidthSample of Relief Plane (mm) Sample of Relief Plane (mm)______________________________________27 0.073 35* Damaged in its course.28 0.091 36* 0.11029 0.058 37* 0.14930 0.087 38* 0.10231 0.099 39* 0.11732 0.065 40* 0.12633 0.086 41* 0.13534 0.048______________________________________
Embodiment 4
HfC powder of 73% by wt., TiC 0 .75 powder of 12% by wt., Al powder of 10% by wt. and Hf powder of 5% by wt. are all ground and mixed together in the same manner as embodiment 1, to produce binder powder having average particle size shown in Table 5 below. The produced binder powder is mixed with cBN powder shown in Table 5 and deaired as in embodiment 1. The resultant powder is then sintered under the pressure of 50 Kb, at the temperature of 1300° C. for 30 minutes, thereby to obtain sintered compacts.
Each of the sintered compacts is processed to be a insert for cutting. The outer circumference of a cylinder of an austempered ductile cast iron FCD100 member (hardness H B =300) is cut by dry process at the cutting speed of 150 m/min, depth of cut 0.15 mm and feed rate of 0.15 mm/rev. The cutting time during which the abrasion width of a relief plane reaches 0.3 mm is measured. The result of the test is shown in Table 5.
TABLE 5______________________________________AverageParticle Distribution AverageSize of Amount of cBN Particle CuttingSam- Binder of cBN Particle Size Size of Timeple (μm) (vol %) (μm:%) cBN (μm) (min)______________________________________42 0.3 55 0-1:35 3.6 47 2-4:45 4-8:2043 0.35 45 0-1:40 2.3 49 1-2:25 3-6:3544 0.5 68 0-1:40 3.8 36 3-6:6045 0.2 73 0-1:75 2.2 28 3-6:2546 0.42 62 0-1:45 3.1 34 3-6:5547 0.41 58 0-2:80 2.1 31 3-6:2048 0.29 52 0-1:40 1.9 41 1-2:25 3-6:3549 0.3 70 0-2:65 2.8 32 2-4:3550 1.3 60 0-1:32 4.0 26 3-6:6851 1.4 50 3-6:100 4.1 2552 2.0 70 4-8:100 6.0 20 53* 0.3 78 0-2:60 2.9 8 4-8:40 54* 0.25 43 0-1:50 3.3 Damaged 3-6:50 in 6 min. 55* 1.5 78 2-4:30 4.2 Damaged 3-6:70 in 4 min.______________________________________
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.
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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A hard sintered compact for tools is a sintered compact obtained by super-high pressure sintering of 45-75% by vol. of cubic boron nitride powder and the remaining proportion of binder powder. The binder includes 5-25% by wt. of Al and the remaining proportion of at least one species of compounds represented by (Hf 1-z M z ) C, where M denotes elements of IVa, Va and VIa groups in a periodic table except for Hf, and 0≦z≦0.3 is satisfied. Because of this composition, improvements are made in strength, wear resistance and heat resisting property of the binder, and a hard sintered compact for tools having excellent strength and excellent wear resistance can be obtained.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to work knives and, more particularly, work knives having multiple purposes including, without limitation, cutting, scraping, grouting, and plastering. The knife is further adapted to the particular needs of left handed workers as well as environments in which it would be advantageous to employ one's left hand for a given purpose.
2. Prior Art
The Field of utility knives includes many examples of previous attempts, extending over many years, all of which are directed to the provision of a utility knife which satisfies one or more of the historic concerns associated therewith. These concerns include those of cost, safety, durability, and ergonomics, that is, compatibility with the human hand. A further need in the prior art is that for the storage of spare knife blades within the utility knife itself. A further need, however rarely addressed in the prior art, is that of a utility knife usable for many purposes and, as well, adaptable for use by workers which are both left and right handed.
The traditional trapezoidal-shaped, double-ended utility knife blade has been well known for over sixty years. See, for example, U.S. Pat. No. 2,145,985 (1939) to Krajecik. More recent efforts to improve upon the classical utility knife are reflected in U.S. Pat. No. 5,012,581 (1991) to Fletcher; U.S. Pat. No. 5,490,331 (1996) to Gold; U.S. Pat. No. 5,613,300 (1999) to Schmidt; U.S. Pat. No. 5,623,737 (1997) to Moyer; and U.S. Pat. No. 6,058,607 (2000) to Gringer.
None of this art, nor other art known to the within inventor, discloses a utility knife having a handle surface which is particularly proportioned to the human hand and the gripping function associated therewith when such a knife is held. Further, the prior art does not provide for a utility knife having integrated therewith a non-utility knife portion capable of both cutting and non-cutting functions. Also, the prior art does not provide for a multi-purpose utility knife having a portion thereof which may be selectably changed on the basis of whether or not the user is left or right handed or if a given work assignment, project or problem within a work environment is one in which a “left” versus a “right” handed tool would be more advantageous for such a particular purpose.
The present invention addresses, in an integrated fashion, all of the above long felt needs that have existed in the art of utility knives.
SUMMARY OF THE INVENTION
A multi-purpose work knife, comprises a universal elongate handle (“UEH”) extending generally upon a UEH axis, said handle having a compound, convex curvature and an assembly within, at a top surface of a first end of said UEH, for holding a UEH utility knife blade in a selectable longitudinal position defined by a cutting edge of said UEH blade, said UEH also defining substantially oval radial cross-sections between said blade holding assembly and a second end thereof, said cross-sections defining slightly smaller radii at about a center region of said UEH, said second end comprising complemental securement means; and a selectable non-universal portion (“SNP”) having a first end and a second end, said second end comprising means for selectable complemental securement to said UEH complemental securement means, said second end of said SNP having a like radius and curvature to said second end of said UEH at opposing surfaces thereof, said UEH axis passing through said complemental securement means of said surfaces of said second ends of said UEH and SNP respectively, said SNP further comprising, at a first end and top surface thereof, an assembly for selectably holding a knife blade having a cutting edge projecting away from said first end of said SNP, in which said cutting edge of said SNP blade defines an angle which intersects said axis of the UEH blade, at a virtual extension external to said work knife, in a range of about 20 to about 40 degrees. Said SNP may selectably take several forms including a left angled axis relative to the axis of the UEH, a right angled axis relative thereto, and an axis substantially co-linear with said UEH axis.
It is an object of the invention to provide a multi-purpose work knife having a universal portion corresponding to the classical function of a utility knife and having a non-common portion which provides for adaptability of the knife to the needs of left versus right handed persons and, as well, affords numerous additional cutting and non-cutting functions.
It is another object to provide a multi-purpose work knife of the above type having a surface curvature and geometry particularly adapted for the requirements of the human hand during the gripping of a utility knife.
It is thereby a further object of the invention to provide an improved multi-purpose knife which is usable with equal facility by both left-handed and right-handed persons.
It is a still further object to provide a work knife which, alternatively, may be employed in numerous non-utility cutting and non-cutting applications.
The above and yet other objects and advantages of the present invention will become apparent from the hereinafter set forth Brief Description of the Drawings, Detailed Description of the invention and claims appended herewith.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the inventive multi-function work knife.
FIG. 2 is a top perspective view of the knife of FIG. 1 .
FIG. 3 is a bottom elevational view thereof.
FIG. 4 is a side elevational view of the invention showing the difference in angulation of the respective planes of the utility knife portion of a tool versus the non-utility knife portion thereof.
FIG. 5 is a top plan exploded view of the multi-purpose work knife.
FIG. 5A is a front plan view of the non-universal portion of the work knife showing the blade holding means associated therewith.
FIG. 6 is a bottom view of the inventive knife particularly showing the relationship between the various virtual axes which define the invention.
FIG. 7 is a front elevational view of the universal handle portion of work knife.
FIG. 8 is a front elevational view of the selectable non-universal portion of the inventive multi-purpose work knife.
DETAILED DESCRIPTION OF THE INVENTION
With reference to views of FIGS. 1 to 6 , the present inventive multipurpose work knife 10 may be seen to include a universal elongate handle part 12 (hereinafter the “universal handle”) or “UEH” the elongation of which extends generally along an “UEH” axis 14 . Said universal handle, as may be noted with reference to FIGS. 1 and 4, defines a compound convex generally cylindrical surface in which a transverse cross-section thereof defines slightly smaller radii at about a center region 16 thereof.
With further reference to FIGS. 1 to 6 , it is noted that the universal handle 12 includes a first end 18 and a second end 20 . Upon a top surface of said universal handle is provided a knife-blade holding assembly 22 which includes several constituent elements, these including a thumb recess 24 , a blade control knob 26 and a blade channel 28 . A utility knife blade 30 and its cutting edge 32 are held within channel 28 and adjustably positioned by the function of knob 26 . Therein, blade 30 may, during periods of non-use, be held in a fully withdrawn position as is shown in FIGS. 2 and 3. Therein, said utility knife blade 30 will reside slightly inwardly of distal edge 34 of first end 18 of universal handle 12 . Said edge defines an axis 69 (see FIG. 2) which exhibits an angle B of about 20 degrees relative to said UEH axis 14 . When knob 26 is employed to facilitate the fullest possible extension of utility knife blade 30 , cutting edge 32 thereof and its associated point 36 will project well beyond distal edge 34 end of first end 18 of universal handle 12 of the work knife 10 . It is to be appreciated that the views of FIGS. 1 and 6 show the inventive knife with UEH blade 30 inserted within holding assembly 22 , while that of FIGS. 2, 3 , and 5 show the work knife and holding means 22 without blade 30 . It is further noted that said cutting edge 32 defines an axis 37 which exhibits an angle G relative to distal edge 34 , and an angle I relative to UEH axis 14 .
A variety of strategies may be employed to secure blade 30 within holding assembly 22 . One such strategy is shown in the views of FIG. 5 . Therein, channel 28 is provided with a linear plurality of pins 38 which are placed and dimensioned for complemental engagement of apertures 40 within the blade 30 . This approach enables a user to select a desired degree of extension of blade 30 from distal edge 34 of first end 18 of the universal handle 12 . Also shown is knob 26 of holding assembly 22 having an axle (not shown) which threadly engages a vertical bore 42 within said channel 28 of the holding assembly 22 . It should be appreciated that holding assembly 22 further includes a hold-down plate 44 which is also secured by knob 26 , this to maintain stability of blade 30 within the assembly 22 and to contribute to the safety and aesthetics associated with the entire structure.
As may be noted with reference to the perspective views of FIGS. 1, 7 , and 8 , radial cross-sections of universal handle 12 defines substantially oval cross-sections between said thumb recess 24 of the holding assembly 22 and second end 20 of the universal handle 12 . Included within said second end 20 of universal handle 12 is female means 45 or complemental securement means, later described below.
With reference to the views of FIGS. 1 through 6, the inventive handheld utility knife 10 may be seen to further include a selectable non-universal portion (“SNP”) 46 having a first end 48 and a second end 50 having a male means 51 is proportioned for complemental engagement with female means 45 of second end 20 of said universal handle 12 . See FIG. 5 . It is further noted that said UEH axis 14 (see FIG. 2) of said universal handle extends through interface 53 which exists at a complemental joinder between said first ends 20 and 50 and into said non-universal portion 46 to a thumb recess 50 which is associated with a blade holding assembly 52 of said non-universal portion 56 , having an axis 54 . See FIGS. 2 and 6. It is to be appreciated that, in a preferred embodiment, the inventive utility knife will be sold in a kit which is provided with both a left and a right hand embodiment of said non-universal portion 46 , this to accommodate the needs of respective right and left handed workers and, as well, to accommodate particular work or cutting environments in which the use of either a left or right handed non-universal portion 46 would be particularly advantageous to the worker without regard to whether the worker is right or left handed. That is, there exist numerous work environments and work spaces in which the desired angle of cut for the work project, or preferred leverage of the worker, is more readily achieved with a non-universal portion directed either to the left or to the right of said UEH axis 14 of universal handle 12 . It is, thereby, to be understood that while the within drawings, and associated description, describe a selectable non-universal portion 46 which, in top view, projects to the left relative to said UEH axis 14 , the instant invention is equally applicable to the use of a selectable non-universal portion which is substantially a mirror image of the non-universal portion 46 shown in the figures and which, thereby, would project to the right relative to said axis 14 . An angulation A of this projection is defined by said axis 54 (see FIG. 2) of non-universal portion 46 relative to UEH axis 14 . This angulation falls in a range of about 110 to about 140 degrees.
Said holding assembly includes a substantially triangular recess 56 (see FIGS. 2 and 5) as well as a securement knob 58 .
As may be noted in FIGS. 1, 5 , 5 A, and 6 , holding assembly 52 is adapted for the securement of a substantially triangular blade 60 or a blade having the general geometry of a parallelogram, and having a cutting edge 61 substantially parallel to an edge of said SNP first end.
It is, however, to be noted that the holding assembly 52 of non-universal portion 56 is adapted to secure transverse, as opposed to longitudinal, movement of blade 60 . This may be more fully appreciated with reference to the view of FIG. 5A in which there is shown a plurality of projections 62 from triangular recess 56 of non-universal portion 46 . Provided on blade 60 is a corresponding plurality of apertures 64 to permit the positioning of blade 60 upon the projections 62 of channel 56 . As in the case of first holding assembly 22 , knob 58 includes an axle, not shown, which threadly engages a vertical bore 66 (see FIG. 5) to selectably effect the positioning and securement of a hold down piece 68 (see FIGS. 4 and 8) upon blade 60 .
One distinguishing parameter of the present invention is that an axis 67 of channel 28 of first holding assembly 22 will, at a point of intersection with UEH axis 14 and, at the axis of rotation of knob 26 , define an acute angle B in a range of 10 to 25 degrees. (See FIG. 2 ). It is further noted that, in a preferred embodiment, distal edge 34 of first end 18 of universal handle 12 defines an axis 69 which intersects said UEH axis 14 at an angle C which is in a range of 40 to 50 degrees, and which is substantially parallel with said axis 54 of said SNP blading holding assembly 52 . See FIGS. 2 and 6.
Generally, first end 48 of non-universal portion 46 is linear and defines an axis 70 which, while substantially normal to said axis 54 , intersects said UEH axis 14 (to the left of non-universal portion 46 ) at a virtual angle D which is in a range of 20 to 40 degrees. This angle will be substantially the same in either the left or right-handed embodiment of the non-universal portion. In the left handed embodiment thereof, i.e., in the embodiment shown in figures, said axis 69 , corresponding to a virtual extension of said edge 34 of first end 18 of universal portion 12 , will intersect with said axis 70 at an angle E which is typically in a range of 80 to 120 degrees.
It has also been found that such an angulation H of axis 70 of the edge 61 of SNP blade 60 relative to axis 37 of edge 32 of UEH blade 30 produces an advantageous leverage to a user of the present work knife, if it is in a range of 20 to 40 degrees. It is to be appreciated that the flared structure of triangular blade 60 of the non-universal portion will have cutting, scraping, grouting, plastering and other applications which will enhance the generalized utility of the present invention.
The utility of the invention is also furthered by triangular side surfaces 72 , 74 and 75 (see FIGS. 4 to 8 ) of the handles as well as the relative positioning of plane 76 of utility knife blade 30 relative to plane 78 which is defined by triangular blade 60 (see FIG. 4 ). Therein, it has been found that an obtuse angle F, formed at an intersection of said planes in a range of 160 to 170 degrees, is most useful. That is, the advantages of the invention are yet further enhanced by such relative angulation F of planes 76 and 78 relative to each other.
It is to be appreciated that said SNP may selectably take several forms including a left angled axis relative to the axis of the UEH, a right angled axis relative thereto, and an axis substantially co-linear with said UEH axis.
While there has been shown and described the preferred embodiment of the instant invention, it is to be appreciated that the invention may be embodied otherwise than is herein specifically shown and described and that, within said embodiment, certain changes may be made in the form and arrangement of the parts without departing from the underlying ideas or principles of this invention as set forth in the claims appended herewith.
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A multi-purpose work knife includes a universal elongate ergonomically-shaped handle (UEH) which defines an axis and includes a blade having an UEH blade axis. Within the handle portion, a channel member is received in a forwardly extending cavity and movably receives a cutting blade carrier for axial movement relative to the handle portion. A selectable non-universal portion (SNP) is secured at one end to said UEH at a plane of continuity of curvature thru which the UEH axis passes. The SNP holds non-standard blade at an angular offset relative to the UEH axis. A cutting edge of the SNP blades defines a virtual angle which intersects the UEH axis within a range of 20 to 30 degrees.
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CLAIM OF PRIORITY
[0001] This application is a divisional application of the following application:
U.S. patent application Ser. No. 10/002,483, entitled APPARATUS AND METHOD FOR ATMOSPHERIC PRESSURE REACTIVE ATOM PLASMA PROCESSING FOR SURFACE MODIFICATION, inventor Jeffrey W. Carr, filed Nov. 1, 2001 (Attorney Docket No. CARR-01000US2), which claims priority from the following application that is hereby incorporated by reference in its entirety:
[0003] U.S. Provisional patent application No. 60/265,332, entitled APPARATUS AND METHOD FOR ATMOSPHERIC PRESSURE REACTIVE ATOM PLASMA PROCESSING FOR SHAPING OF DAMAGE FREE SURFACES, filed Jan. 30, 2001 (Attorney Docket No. CARR-01000US0).
CROSS-REFERENCE TO RELATED APPLICATIONS
[0004] This application is related to the following co-pending application which is hereby incorporated by reference in its entirety:
[0005] J U.S. patent application Ser. No. 10/002,035, entitled APPARATUS AND METHOD FOR ATMOSPHERIC PRESSURE REACTIVE ATOM PLASMA PROCESSING FOR SHAPING OF DAMAGE FREE SURFACES, inventor Jeffrey W. Carr, filed Nov. 1, 2001 (Attorney Docket No. CARR-01000US1)
[[0006]] The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California.
FIELD OF INVENTION
[0007] The field of the invention relates to shaping surfaces using a gas plasma.
BACKGROUND
[0008] Modern materials present a number of formidable challenges to the fabricators of a wide range of optical, semiconductor, and electronic components, many of which require precision shaping, smoothing, and polishing. Current methods, such as conventional grinding and polishing, have a number of disadvantages. Physical contact methods, such as grinding, abrasive polishing, diamond turning and ion milling, involve physical force at the microscopic scale and can create damage in the subsurface of the material being treated. Physical contact methods also have a trade-off between speed and quality. Smooth surfaces can require the use of very slow material removal rates, while hard materials such as silicon carbide can be extremely difficult to polish. Soft or delicate structures can also be difficult to polish, as the physical force involved can crack or bend the structures. Some materials such as glass can also end up with a surface layer of redeposited material, which can affect the properties and behavior of the manufactured component.
[heading-0009] Damage-free Laser Optics
[0010] In one example of such a manufacturing challenge, optics produced with current or prior art polishing methods cannot withstand the high intensity of light produced by high-powered laser systems. One of the engineering challenges in such an advanced system is the need for a large number of defect-free optics to be produced within an acceptable period of time and at an acceptable cost. Subsurface defects in such an optic can cause cracks to form on the rear surface of lenses exposed to high ultraviolet laser light levels. These cracks can grow until a large fraction of the light is obscured or until the lens fractures. Some of these lenses also serve as a vacuum barrier, making catastrophic failure a serious safety concern.
[0011] Conventional abrasives-based polishing can be used for many materials. This polishing process is both chemical and mechanical, involving surface and solution chemistry as well as mechanical abrasion. Mechanical abrasion rapidly removes material, but can produce sub-surface damage and cause the damage to propagate deeper into the workpiece. The chemical portion dissolves and redeposits glass, forming a relatively smooth surface. The chemical kinetics of redeposition favor the formation of smooth surfaces, as high spots are mechanically abraded away while holes are filled through redeposition.
[0012] This process of redeposition can lead to problems in some applications. Analysis of the redeposition layer reveals a tremendous number of contaminants, mostly from the abrasive but also from previous polishing steps. This redeposition layer can affect the adhesion and physical properties of optical coatings. Below this redeposition zone can be an underlying zone of damaged glass, up to tens of microns thick or more. When high fluxes of light pass through this zone, damage sites can nucleate and grow, eventually leading to failure of the entire optic. The quality of the polish, and the underlying redeposition layer and subsurface damage, ultimately control how much light can be transmitted through the optics.
[0013] In order to produce optics capable of routinely withstanding laser intensities as high as 12 J/cm 2 , a process is required to remove the 20-30 microns of damaged material. Conventional polishing can be used to remove this damage layer, but it must be done very slowly—on the order of about 0.1 μm per hour. Polishing for this length of time also necessitates periodic checks of the shape of the part using precision metrology.
[heading-0014] Wet Etching
[0015] Another approach to removing the damage layer in an optic is a wet chemical etch. In such a process, only a limited amount of material can be removed before the surface becomes excessively pitted, with a resulting increase in the amount of light scattered by the optic. Optics processed by wet etch have been tested, with the disappointing result that the damage threshold was unaffected.
[heading-0016] Ion Milling
[0017] Another approach utilizes ion milling after conventional polishing. Ion milling is a well-established technique for removing small amounts of material from a surface using a kinetic beam of ions. Some advantages of ion milling include: no surface contact, no weight on the optic, no edge effects, and correction of long spatial wavelength errors.
[0018] There are numerous disadvantages to ion milling, however, including high surface temperatures, an increase in surface roughness, and the need for vacuum. The temperature is dependant on beam current, so that an increase in etch rate produces an increase in temperature often surpasses several hundred ° C. Nearly all heat must be removed through the chuck, usually requiring a good thermal connection between the workpiece and the holder. This is difficult when working on transmission optics because they must be held by the edges so as not to damage the polished surface. Further, ion beams cannot smooth surfaces. For small amounts of material removal, roughness can be held constant. Large amounts of material removal cause an unfortunate increase in roughness.
[heading-0019] Reduced Pressure Plasma Methods
[0020] Another approach involves plasma etching at reduced temperature, which is used extensively in the semiconductor industry for processing of a wide variety of materials including semiconductors, metals and glasses. Reactive ions are believed to be responsible for the majority of material removal, leading the technique to be known as reactive ion etch (RIE). Considerable effort has been put into developing plasmas with uniform etch rates over the entire discharge, making RIE unsuitable for the production of figured precision components. The greatest practical drawback to RIE for precision finishing of optical components is the need for vacuum and a low material removal rate. Translating either the source or workpiece with precision on a complicated path inside a vacuum chamber is challenging, especially in the case of large optics. In-situ metrology would also be awkward.
[0021] A modified RIE for polishing at reduced pressure has been built using a capacitively coupled discharge. Named “Plasma Assisted Chemical Machining” (PACE), the system has been successful in shaping and polishing fused silica. While the parts polished by PACE have shown no evidence of subsurface damage or surface contamination, it has been found that greater sub-surface damage present before etching resulted in an increased roughness after etching.
[0022] A major limitation of this capacitively-coupled discharge approach is the requirement that the workpiece be either conductive or less than 10 mm thick. In addition, etch rates are dependant on part thickness, decreasing by a factor of ten when thickness changed from 2 to 10 mm. Above 10 mm the rates are too low to be of much use. If metrology is needed in an iterative procedure, the chamber must be vented and pumped down for the next etch step. The convergence rate for PACE is also typically very low, resulting in a long, expensive multi-step process. PACE technology was recently improved by the substitution of a microwave plasma source for the capacitively coupled system, but the rates are still too slow for optics manufacturing.
[heading-0023] Atmospheric Pressure Plasma Methods
[0024] In yet another approach, a direct current (DC) plasma can be used at atmospheric pressure to thin wafers. Originally called a “Plasma Jet” and also referred to as Atmospheric Downstream Plasma (ADP), such a system uses argon as the plasma gas, with a trace amount of fluorine or chlorine for reactive atom production. The main intent of the device is to do backside thinning of processed silicon wafers for smart card and other consumer applications. With the ADP tool, wafers are thinned in a batch mode by placing them on a platten and using planetary type motion to move the sub-aperture plasma in a pseudo-random fashion across the surface.
[0025] Unfortunately, atmospheric DC plasma jets such as ADP are not well suited for the precise shaping and smoothing of surfaces or for material deposition. Because the reactive gas is mixed with the bulk gas prior to excitation, the reactive species in the plasma are widely distributed across the discharge. This substantially increases the footprint and the minimum feature size that can be etched into a surface. Furthermore, the electrodes that are used to establish the arc are eroded by the reactants. This adds particulates to the gas stream, as well as causing fluctuations in plasma conditions, and accounting for the reduced uniformity compared to RIE systems. Detrimental electrode reactions also preclude the use of oxygen and many other plasma gases.
[0026] Another plasma process, known as Chemical Vapor Machining (CVM), is a radio frequency (RF) plasma process that has been used to slice silicon. This plasma is generated around a wire or blade electrode immersed in a noble gas atmosphere containing a trace of reactive components. Like the PACE process it closely resembles, material removal through CVM is entirely chemical in nature. The damage for CVM and wet chemical etching are similar, close to the intrinsic damage typically found in silicon used in the semiconductor industry.
[0027] Several performance characteristics limit the applications of CVM. First, the non-rotationally symmetric nature of the footprint makes the process difficult to model and control. Process rates are limited by the rate at which the plasma converts the reactive precursor gas into radical atoms. The device is difficult to scale up, limiting the maximum removal rate and the practical limit for fine-scale material removal. While no vacuum is required for CVM, the workpiece must be enclosed in a vessel to contain the plasma atmosphere.
[0028] Another type of plasma jet has been developed to etch and deposit material on surfaces as well as to clean surfaces, known as an “ApJet.” This system consists of two concentric electrodes that generate a DC plasma which exits through a nozzle. The discharge is at a low temperature, making the process suitable for cleaning temperature-sensitive materials. The ApJet is not suitable for precisely shaping and polishing surfaces, as etch rates are low and the electrodes and nozzle erode and deposit material onto the surface. This makes precision control difficult. Furthermore, the ApJet cannot smooth rough surfaces.
BRIEF SUMMARY
[0029] Systems and methods in accordance with the present invention overcome deficiencies and obstacles in the prior art to produce a highly-controllable, precise, atmospheric, non-contact material removal process. These systems and methods also provide improved processes for shaping geometric surfaces and rapidly shaping hard-to-machine materials, as well as rapidly thinning finished silicon devices with high smoothness and minimal thickness variation.
[0030] One method for shaping a surface of a workpiece involves placing the workpiece in a plasma processing chamber that includes a plasma torch, such as an ICP torch. The workpiece and plasma torch are moved with respect to each other, whether by translating and/or rotating the workpiece, the plasma, or both. Reactive atom plasma processing is used to shape the surface of the workpiece with the discharge from the plasma torch. Reactive atom plasma processing can also be used for purposes such as to planarize, polish, clean, or thin the workpiece. The processing may cause minimal or no damage to the workpiece underneath the surface, and may involve removing material from the surface of the workpiece.
[0031] Also included in the present invention are tools and systems for accomplishing these and other methods. Such a system for shaping the surface of a workpiece can involve a plasma torch configured to shape the surface of a workpiece using a reactive plasma process. A translator can be used to translate the workpiece, the torch, or both, such that the desired shape, planarization, polishing, or cleaning is achieved. The torch can be contained in a plasma processing or other appropriate chamber.
BRIEF DESCRIPTION OF THE FIGURES
[0032] FIG. 1 is a diagram of a system in accordance with one embodiment of the present invention.
[0033] FIG. 2 is a diagram of the ICP torch of FIG. 1 .
[0034] FIG. 3 is a diagram showing relative concentrations of reactive atoms and reactive ions in a plasma discharge that can be used in accordance with one embodiment of the present invention.
[0035] FIG. 4 is a graph of a footprint of a tool that may be used in accordance with one embodiment of the present invention.
[0036] FIG. 5 is a flowchart showing a process in accordance with one embodiment of the present invention.
[0037] FIG. 6 is a flowchart showing another process in accordance with one embodiment of the present invention.
DETAILED DESCRIPTION
[0038] Systems and methods in accordance with the present invention have advantages over prior art systems, such as PACE and chemical vapor machining, in that the number of potential products increases to include devices fabricated from heat sensitive components and heterogeneous materials that are typically difficult to polish by chemical means. Polishing and planarization are now be possible with little heat gain and minimal material removal.
[0039] FIG. 1 shows one embodiment of a reactive atom plasma (RAP) system that can be used in accordance with the present invention. FIG. 1 shows an ICP torch in a plasma box 106 . The torch consists of an inner tube 134 , an outer tube 138 , and an intermediate tube 136 . The inner tube 134 has a gas inlet 100 for receiving a reactive precursor gas from the mass flow controller 118 . The intermediate tube 136 has a gas inlet 102 for receiving an auxiliary gas from the flow controller 118 . The outer tube 138 has a gas inlet 104 for receiving a plasma gas from the mass flow controller 118 . The mass flow controller 118 receives the necessary gasses from a number of gas supplies 120 , 122 , 124 , 126 , and controls the amount and rate of gasses passed to the respective tube of the ICP torch. The ICP torch generates a plasma discharge 108 , which can be used to, for example, shape or polish a workpiece 110 located on a chuck 112 in the workpiece box 114 . In this embodiment, the plasma box 106 and workpiece box 114 are separate, allowing the plasma discharge 108 and/or torch to pass at least partially between the plasma 106 box and the workpiece box 114 . The workpiece box 114 has an exhaust 132 for carrying away any process gases or products resulting from, for example, the interaction of the plasma discharge 108 and the workpiece 110 . In other embodiments, there may not be separate boxes for the plasma torch and the workpiece.
[0040] The chuck 112 in this embodiment is in communication with a translation stage 116 , which is adapted to translate and/or rotate a workpiece 110 on the chuck 112 with respect to the plasma discharge 108 . The translation stage 116 is in communication with a computer control system 130 , such as may be programmed to provide the necessary information or control to the translation stage 116 to allow the workpiece 110 to be moved along a proper path to achieve a desired shaping or polishing of the workpiece. The computer control system 130 is in communication with an RF power supply 128 , which supplies power to the ICP torch. The computer control system 130 also provides the necessary information to the mass flow controller 118 .
[0041] The torch itself can be seen in greater detail in FIG. 2 . An induction coil 140 surrounds the outer tube 138 of the torch near the plasma discharge 144 . Current from the RF power supply flows through the coil 140 around the end of the torch. This energy is coupled into the plasma. Also shown are the excitation zones 142 , into which the reactive precursor is injected, and the plasma envelop 146 , which can be for example a sheath of argon gas.
[0042] One method for using such a system is shown in FIG. 5 . In this method, a workpiece is placed in a plasma processing chamber that includes a plasma torch 500 . At least one of the workpiece and the plasma torch is translated and/or rotated, such as by translating the workpiece with respect to the torch 502 . Reactive atom plasma processing is then used to shape the surface of the workpiece with the discharge from the plasma torch 504 .
[0043] In another method, shown in FIG. 6 , the workpiece is again placed in a plasma processing chamber including a plasma torch 600 . A controlled flow of precursor is placed in a central channel of the plasma torch 602 . A plasma gas is introduced through an outer tube 604 , and an auxiliary gas is introduced through an intermediate tube of the plasma torch 606 . The gases can be introduced relatively simultaneously. Energy is coupled to the plasma discharge in an annular region of the plasma torch 608 . At least one of the workpiece and the plasma torch is translated and/or rotated, such as by translating the workpiece with respect to the torch 610 . Reactive atom plasma processing is then used to shape the surface of the workpiece with the discharge from the plasma torch 612 .
[heading-0044] Chemistry
[0045] A reactive atom plasma process in accordance with the present invention is based, at least in part, on the reactive chemistry of atomic radicals formed by the interaction of a non-reactive precursor chemical with a plasma. In one such process, the atomic radicals formed by the decomposition of a non-reactive precursor interact with material on the surface of the part being shaped. The surface material is transformed to a gaseous reaction product and leaves the surface. A variety of materials can be processed using different chemical precursors and different plasma compositions. The products of the surface reaction in this process must be a gas under the conditions of the plasma exposure for etching to take place. If not, a surface reaction residue will build up on the surface which will impede further etching.
[0046] In one process in accordance with the present invention, the chemistry is specific to fluorine and materials that react with fluorine to form gaseous products. Following are three specific examples where weight loss was measured. The materials processed include:
Silicon dioxide (fused quartz) where the balanced reaction of concern is
SiO 2 +CF 4 ->SiF 4 +CO 2
Silicon carbide works with or without the addition of O 2 . The use of O 2 can greatly speed the operation. One such balanced equation is given by:
SiC+CF 4+2 O 2 ->SiF 4+ 2CO 2
Silicon works with or without addition of oxygen to the plasma. Oxygen can also be supplied by the ambient air. A balanced equation that can be used with the process is given by:
Si+CF 4 +O 2 ->SiF 4 +CO 2
The reaction may also work with CF 4 supplied by the device and ambient oxygen in the tool enclosure.
[0051] Other fluorocarbons and molecules containing fluorine can work as well. SF 6 has been used as the chemical precursor to successfully etch silica glass. The equation can be the same as for CF 4 , such as may be given by:
3SiO 2 +2SF 6 ->3SiF 4 +2SO 2 +O 2
or
3SiO 2 +2SF 6 ->3SiF 4 +2SO 3
In addition to SF 6 , a large number of fluorine-containing chemicals may be suitable for use as reactive precursors. For example, chemicals of the type C n F 2n+2 , such as C 2 F 6 , C 3 F 8 , and C 4 F10 can be used. Fluorine chemicals with other cations may also be suitable, as well as F 2 . For work on materials that do not contain silicon, such as, but not limited to, oxides, metals, carbides, and organic materials, a different reactive atomic species may be appropriate, such as chlorine or bromine. Compounds containing these elements may also be suitable as reactive precursors. An example of such a suitable class of chemicals would be the class of halocarbons. Mixtures of more than one reactive precursor can also be used.
[0054] In the above examples, the reactive precursor chemical can be introduced as a gas. Such a reactive precursor could also be introduced to the plasma in either liquid or solid form. Liquids can be aspirated into the plasma and fine powders can be nebulized by mixing with a gas before introduction to the plasma. In fact, an aqueous solution of HF can be particularly effective because it supplies both fluorine for etching and oxygen for carbon removal, if needed. The equations for such a process may be given by:
SiO 2 +4HF->SiF 4 +2H 2 O
or
SiC+4HF+2O 2 ->SiF 4 +CO 2 +2H 2 O
Such a process has several advantages over the RIE process. RIE requires a vacuum, whereas RAP processing can be used at atmospheric pressure. RAP has much higher material removal rates and can be used as a sub-aperture tool to precisely shape surfaces, whereas RIE is best suited to remove small quantities of material across an entire surface. Finally, RIE cannot smooth rough surfaces whereas RAP processing rapidly polishes and etches surfaces.
ICP Plasma Torch
[0058] An inductively-coupled plasma (ICP) is an excellent source of reactive atoms useful for shaping damage free surfaces. An ICP discharge has previously been used to produce crystalline films of a number of oxides, such as MgO, ZrO 2 , NiO, SnO 2 , TiO 2 , ZnCr 2 O 4 , Cr 2 O 3 , CoCr 2 O 4 , NiCr 2 O 4 , and several rare earth oxides. Superconducting thin films of Bi—Pb—Sr—Ca—Cu—O have also been fabricated with ICP plasma spray methods.
[0059] The high electrical conductivity of partially ionized gases (for example, 120 ohm/cm-1 at 15,000° K. for argon) may contribute to the ease of inductively coupled plasma formation at high pressures. ICP systems do not require electrodes. A number of gases can be used as the host plasma, though argon may be the principle component. A typical discharge can be characterized by a high current (such as 100 to 1000 amps) and a relatively low voltage (such as 10 to 100 volts). The flowing plasma is not in complete thermodynamic equilibrium, but ion and excited state atom populations can be within 10% of equilibrium values. Electron densities can be high, typically above 10 15 cm − 3, which suggests electron temperatures above 15,000K. A peak temperature of 10,000K can be calculated from the ratio of emission intensities for a set of argon lines (again assuming equilibrium) and gas kinetic temperatures have been estimated to be roughly 6,000K. These high temperatures make the ICP an efficient source for the generation of reactive atoms.
[0060] The current from a 27.12 MHz RF generator flows through a three turn copper load coil around the top of the torch, such as the one shown in FIG. 2 . The energy is coupled into the plasma through an annular “skin region” that is located on the outer edge of the plasma nearest the load coil. The plasma can be supported in a quartz tube by the plasma gas, which can be introduced tangentially to form a stabilizing vortex. The “skin region” is thinnest along the central axis and the droplets or gas easily penetrate the discharge. As the droplets travel through the plasma they becomes progressively desolvated, atomized, excited, and ionized. The relative distribution of ions and atoms in the discharge is represented in FIG. 3 . Spatial profiles at five places in the plasma indicate that the excited ion population decays faster than that of the neutral atoms, most likely a result of ion-electron recombination. The maximum atomic emission from the material injected into the plasma occurs several millimeters above the load coil near the visible tip of the discharge (zone 3 and 4). Radiative decay in this region is used to spectroscopically determine the composition of the injected material.
[0061] A standard, commercially-available three tube torch can be used, such as one having three concentric tubes as discussed above. The outer tube can handle the bulk of the plasma gas, while the inner tube can be used to inject the reactive precursor. Energy can be coupled into the discharge in an annular region inside the torch. As a result of this coupling zone and the ensuing temperature gradient, a simple way to introduce the reactive gas, or a material to be deposited, is through the center. The reactive gas can also be mixed with the plasma gas, although the quartz tube can erode under this configuration.
[0062] Injecting the reactive precursor into the center of the excitation zone has several important advantages over other techniques. Some atmospheric plasma jet systems, such as ADP, mix the precursor gas in with the plasma gas, creating a uniform plume of reactive species. This exposes the electrodes or plasma tubes to the reactive species, leading to erosion and contamination of the plasma. In some configurations of PACE, the reactive precursor is introduced around the edge of the excitation zone, which also leads to direct exposure of the electrodes and plasma contamination. In contrast, the reactive species in the RAP system are enveloped by a sheath of argon, which not only reduces the plasma torch erosion but also reduces interactions between the reactive species and the atmosphere.
[0063] The second of the three tubes, optional in some embodiments, can be used to introduce an auxiliary gas, such as at a rate of about 1 L/min. The auxiliary gas can have at least two functions. First, the gas can keep the hot plasma away from the inner tube, since even brief contact may seal the inner tube shut. Second, the gas can be used to adjust the position of the discharge in space.
[0064] The inner diameter of the outer tube can be used to control the size of the discharge. On a standard torch, this can be on the order of about 18 mm. In an attempt to shrink such a system, torches of a two tube design can be constructed, which can have an inner diameter of, for example, about 6 mm, although larger or smaller inner diameters may be appropriate.
[0065] The outer tube gas, such as a plasma gas, can be introduced tangentially and can stabilize the discharge. The tangential introduction can also be maintained with no auxiliary tube. A de-mountable system can be used, where the tubes are individually held and separately replaced. An advantage to such a system is that the length of the outer tube can be lengthened, allowing the plasma to cool down while preventing reactive radical atoms from reacting with air.
[0066] A small torch erosion problem may exist due to a minor portion of the precursor not entering the central zone but instead going around the outside of the plasma. An increase in skin depth (i.e. a thicker energy coupling zone) can constrict the central channel, possibly restricting the precursor flow and allowing some to escape to the periphery. One of the advantages of systems in accordance with the present invention is that there is little to no electrode or nozzle erosion.
[heading-0067] Housing
[0068] As shown in FIG. 1 , there are several basic blocks to a system in accordance with the present invention. A plasma box can be used to house the ICP torch. The plasma box can be used, for example, to shield an operator from radio frequency energy generated during a process, and/or from UV light produced by a plasma. The plasma box can be kept under a slight negative pressure, such as by hooking it up to a chemical hood exhaust system. The entire enclosure can be constructed, for example, from a single sheet of copper that has been folded, rather than connected from individual plates.
[0069] One of the characteristics of RF is that it travels along a surface of a metal rather than through a metal. RF tends to find and leak out of seams and around door frames. Since it may not be possible to completely avoid edges, the edges of the box can be filled with, for example, silver solder and ground with a radius on them, so that there are no sharp points or edges. Pieces that move, such as doors, can be bolted tight, such as through the use of fasteners.
[0070] Holes and windows can be formed or cut into the box, such as to allow for air to enter the plasma and sample box, as well as to allow access for servicing, and to provide a place for visual inspection of the system while operating. Since RF cannot escape from holes much smaller than the wavelength of the radiation (for 13.56 MHz the wavelength in vacuum is about 23 meters), a 100 mm square window can have very little leakage. The windows can use welders glass, for example, and the service holes can be covered with copper tape or other UV-filtering material.
[0071] An aluminum sample box can be used to contain the workpiece and translation stages. Aluminum plates can be bolted together to form such a box. It may be unnecessary to use copper, as there may be no need to shield from RF. The sample box can be connected directly to an adjoining torch box, such as through a circular hole. There can also be a window to allow an operator of the system to watch the part during the process, as well as ventilation openings if necessary. A main exhaust system can be connected to the top of the chamber, although other designs may have the exhaust hose or the stage in a different location, such as may minimize turbulence around the part. There can also be a gauge to measure the pressure differential between the room and the inside of the chamber.
[0072] The main components inside a sample chamber in accordance with the present invention, with the exception of the sample, are the translation stages and the chuck. The chuck can be a relatively simple vacuum system, which can be mounted to the rotary stage and connected to a pump, such as a carbon vane pump, through a rotary or other appropriate connection. The chuck can be smaller than, or equal in size to, the size of the part. If the chuck protrudes past the part, a small amount of chuck material may deposit on the edge or surface.
[heading-0073] Gas Flow Control
[0074] Devices such as rotometers and mass flow controllers can be used to meter gas flow. A system can, for example, use mass flow controllers with piezoelectric transducers to monitor gas flow on all lines except the auxiliary. A power source and control panel can be rack mounted. This can be a commercial unit useful for low pressure capacitively coupled discharges. The rack can also contain the stage controller and the electronics for the mass flow controllers.
[0075] The introduction of reactive gas into the plasma can be controlled by a mass flow controller over a range, for example, of 2000 ml of CF 4 per minute to 0.05 ml per minute, with an accuracy that may be in the range of +/−2.0%. With such a system, it may be possible to go from, for example, 40 L/min of CF 4 (by using CF 4 in the main body of the plasma) to 0.01 ml/min (using dilution).
[0076] There can be several mass flow controllers controlling gas introduction. Having several controllers in series and/or parallel with flow ranges such as from 10 L/min to 0.1 L/min can provide a great deal of flexibility, and allows for complex chemistries of reactive precursor gases. In one example, 1 ml/min of CF 4 is introduced into the central channel using such a system.
[0077] The main gas flow, such as may contain a plasma gas, can serve to supply the discharge with a flowing stream of, for example, argon. The flow rate can be changed over a fairly wide range, such as from zero to about 40 L/min. If the flow is too fast, the plasma may “blow out.” A large flow rate can result in a dilution of both the reactive gas and of the energy put into the system.
[heading-0078] RF Power Supply and Control
[0079] A wide range of power conditions can be used when operating a system in accordance with the present invention. Standard RF units operate at 13.56 MHz, 27.12 MHz, or 40.68 MHz. The frequencies are presently set by the FCC, and may not effect the performance of atomization but may affect the skin depth of the plasma. While a standard RF unit can have a maximum power of 5 to 10 kW, many applications may never require power above 2.5 kW.
[0080] At certain reactive gas flow rates, the additional power may do nothing but deposit more heat on the part. Surface heating on the part can be important to reaction rates and reaction efficiency. Generally, the rates increase with temperature. It may be undesirable to greatly increase the temperature of the part, as reaction products can be produced that condense on cooler areas of the part and on the housing of the device. Too much heat can also cause thermal stress in the part, as well as a change in shape due to thermal expansion. The additional energy at the high power settings can also serve to reduce the number of active species, such as by converting the reactive atoms to ions and reduce their reactivity.
[0081] In one system in accordance with the present invention, the process must produce a volatile reaction product to be successful. The plasma temperature can be between 5,000 and 15,000° C. As the plasma can be a non-equilibrium system, different techniques for estimating temperature can yield different results. The lower value, 5,000° C., is the gas kinetic temperature and may bear the largest responsibility for heating the part.
[0082] The entire system can be mounted on an optical table, or any other appropriate mounting surface or structure. Since the removal tool is a gaseous flow of reactive atoms, it may not be very vibration sensitive. To eliminate any environmental contribution, a clean room or other appropriate enclosure can be built around the sample chamber and torch box.
[heading-0083] Dynamic Range
[0084] One advantage of a system in accordance with the present invention is the dynamic range of material removal. At a low setting, the reactive gas can be delivered in such minute quantities that single atomic layers are removed, such as over a period of seconds or even minutes. At higher settings, the process can remove at least grams of material per minute. While they might not be practical for material removal, very low etch rates can be important for modifying the surface of materials treated with the plasma.
[0085] By using a range of mass flow controllers and using precursor gas in 100%, 10% and 1% mixtures with argon, a dynamic range of five orders of magnitude in etch rate is available in one embodiment, although additional orders of magnitude in etch rate are possible using different ranges and mixtures. At a high end, such as may be achieved by confining a precursor to the central channel, it is possible to introduce 1000 ml/min of 100% CF 4 . On a low end, a 1% mix of CF 4 in argon can be delivered to a central channel with a flow rate of 1 ml/min. Etch rates can be reduced by two more orders of magnitude such as by using a flow controller that operates, for example, from 0 to 10 ml/min and/or by a further 10× or other appropriate dilution of the gas.
[heading-0086] Precision Shaping
[0087] Using conditions such as those described above, it is possible to get a stable, predictable, reproducible distribution of reactive species that is roughly Gaussian in nature, although other distributions are possible and may be appropriate for certain applications. For many applications, it may only be desirable that the distribution be radially symmetric. For example, a 18 mm inner diameter torch may have a spread of about 30 mm. FIG. 4 is a probe trace of a pit produced by a 1.5 kW plasma with a reactive gas flow rate of 50 mls/minute over a 5 minute period. The distance from the load coils (energy induction zone) to the part surface was 25 mm. As the exposure time is increased or decreased, such a hole can get deeper or shallower, but its width may not vary greatly. Therefore, the tool shape produced by the plasma system can be extremely shallow and broad, which can relax the requirements for precision X-Y positioning of the tool or the part.
[0088] An important factor in this process is the fact that the footprint of the plasma discharge can be stable and reproducible, and dependant on controllable parameters. Fairly similar etch rates can be produced if similar systems are run under identical conditions, and the same system can be highly reproducible from day to day. For extremely precise surfaces, the footprint of the tool may need to be measured before each removal step. It may also be possible, however, to determine the footprint as a byproduct of the iterative shaping process.
[0089] If any shape on the part is required, other than a Gaussian depression of various depths, it may be necessary to translate and/or rotate the part relative to the torch, although it may also be possible to translate and/or rotate the torch with respect to the part, or both with respect to each other. If the torch is held stationary and lowered into the part a depression or pit may result. If the torch translates across the part while spinning, a trench may be produced. The floor of the trench can take on the characteristics of the distribution of reactive species in the torch, and also can be determined by how closely the torch paths approach each other on subsequent passes. It may be necessary to move two stages at the same time. To accomplish this, a second controller can be used, such as may be computer- or machine-controlled. A basic system can be limited to a constant rotation speed, with the translation speed across the part being controlled in a stepwise fashion (i.e. go a certain distance at a fixed speed and at a certain point change the speed).
[0090] In such a process, a rough part can be measured for which a fairly accurate estimate of the footprint is known, such as from previous experiments. The final desired part shape may be known, and a pathway for the tool can be calculated to get the final shape from all of the input variables, including such input variables as initial part shape, plasma conditions, dwell time, and removal behavior of the workpiece material. When completed, the part shape could be accurately measured and compared with the desired shape. The difference may be the error in the assumption of the footprint shape.
[0091] To produce an approximation to complex (or flat) surfaces with such a system, the part can be rotated as it is translated in front of the discharge. For uniform material removal in certain applications, the speed of the torch across the surface may need to be constant. For some applications it may be necessary to vary all parameters simultaneously including tool position, part position, gas flow rate, gas flow composition and excitation energy.
[heading-0092] Rapid Polishing of Rough Surfaces
[0093] One of the more surprising and interesting features of systems in accordance with the present invention is the planarization and/or polishing of rough surfaces. Parameters which can dictate the time required to polish glass or other suitable materials with the plasma system include the concentration of species in the plasma gas (both reactants and products) and the temperature of the surface and surrounding gas. Exchange of species on and off the surface, as well as the local redeposition of material during etching, can be principally responsible for the rapid smoothing of rough surfaces, resulting in planarization on at least a local scale.
[0094] The relatively high concentration of species in the plasma, and the local equilibrium established across the boundary layer by this process, can explain why other lower pressure plasma systems such as PACE do not exhibit such a smoothing effect. The higher pressure gas can reduce the mean free path of the products, keeping the products in the surface region for a greater amount of time. In addition, the higher pressure gas can have a greater heat capacity, keeping the near surface region of the solid at a higher temperature. While low pressure plasma temperatures may be the same, the actual amount of heat deposited on the surface using an atmospheric pressure plasma system can be greater due to the higher flux of gas. This is evident in the fact that one system in accordance with the present invention uses a 1.5 to 2.25 kW plasma while the PACE and microwave devices commonly run at a few hundred watts in a maximum configuration.
[0095] Another way to change the amount of material available for deposition, and to affect the rate of planarization or smoothing, is to add a reactant into the plasma that would cause deposition while the fluorine atoms cause etching. A combination of some volatile silicon compound with the addition of oxygen may be sufficient.
[0096] An equilibrium-deposition state in accordance with the present invention is not the same as previous plasma deposition, as the process does not simply fill in holes but rather involves a local redistribution of material at the surface. This may be important for applications where it is necessary that the structure of the final surface material be nearly identical to the bulk phase.
[0097] The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to the practitioner skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalence.
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Reactive atom plasma processing can be used to shape, polish, planarize and clean the surfaces of difficult materials with minimal subsurface damage. The apparatus and methods use a plasma torch, such as a conventional ICP torch. The workpiece and plasma torch are moved with respect to each other, whether by translating and/or rotating the workpiece, the plasma, or both. The plasma discharge from the torch can be used to shape, planarize, polish, and/or clean the surface of the workpiece, as well as to thin the workpiece. The processing may cause minimal or no damage to the workpiece underneath the surface, and may involve removing material from the surface of the workpiece.
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CONTINUITY
This application is a continuation of co-pending U.S. patent application Ser. No. 07/447,888, filed Dec. 7, 1989, now U.S. Pat. No. 5,074,871.
BACKGROUND OF THE INVENTION
The present invention relates to surgical apparatus and procedures, and particularly to a device for excising portions of the atherosclerotic plaque material causing stenosis in an artery.
Atherosclerosis is a condition which progressively affects many arteries of the body with advancing age. It ultimately produces thickening of the medial layer of the arterial wall, which may involve some or all of the circumference of the blood vessel. Eventually, significantly narrowed internal diameter, or stenosis, of the artery results and restricts the flow of blood to the tissue beyond the stenosis, producing symptoms including angina or myocardial infarction in the heart, claudication or gangrene in the legs, high blood pressure, or deterioration of kidney function.
The art and science involved in modern vascular surgery are comparatively young and began with the successful end-to-end repair of severed arteries in Korean war casualties. Atherosclerotic narrowing of arteries then could only be corrected by complete endarterectomy, which required a longitudinal incision through the entire narrowed segment of an artery. Exposure of an artery for this purpose was difficult, and the wounds resulting from the surgery were large. Although results were often gratifying, the practice was not widespread because of resulting problems such as pseudoaneurysms developing in endarterized segments and the potential for vessel wall dissection at the distal endpoint, and because of the difficulty posed both for the patient and for the surgeon. During the 1950's a variety of synthetic tubular grafts were introduced and perfected for partial arterial replacement and bypasses around stenoses. Because of the relative ease of such procedures by comparison with endarterectomy, bypass grafting soon became the dominant means of correcting arterial narrowing within the pelvis and thigh. Advances in surgical technique in the late 1960's made possible the use of the patient's own reversed saphenous vein to bypass occluded arteries on the heart and below the knee.
As the population of the United States has aged as a group, the manifestations of atherosclerosis have, as a group, become this nation's number one health problem in terms of both suffering and cost. While surgical bypass procedures using saphenous vein or prosthetic conduit remain the procedure of choice in most instances, newer technologies have evolved in the last decade to simplify the treatment of atherosclerotic stenoses in an attempt to reduce patient risk, reduce cost, and to make treatment available to more people. In carefully selected cases involving narrowing of short segments of the coronary, renal, iliac, and femoral arteries balloon dilation has been employed with some success. Generally, however, the duration of arterial patency resulting from such procedures is less than for bypass graft procedures. Utilization of lasers to open narrowed arteries has not yet proven to be clinically successful and is very expensive in all aspects.
In recent years a variety of atherectomy devices have been used experimentally in attempts to extend patency. Some of these devices include rotary cutting mechanisms, which restrict their use to stenoses of short length. Some are driven by high-speed electric motors which add to their complexity and increase the likelihood of breakdown while also reducing the amount of responsiveness and taking the ability to control operation out of the surgeon's hands.
Manually-operated devices for relieving arterial stenoses are disclosed, for example, in Lary U.S. Pat. No. 4,273,128, which discloses a device having a plurality of curved knife blades whose edges are directed radially outward, and Fischell et al. U.S. Pat. No. 4,765,332, which discloses a catheter including a proximally-exposed annular cutting edge which is no greater in diameter than an outer sleeve of the catheter to which it is attached. Luther U.S. Pat. No. 4,650,466, discloses a catheter which includes an expansable woven tube portion which can be used to abrade atherosclerotic plaque from the interior wall of the artery. Clark, III, U.S. Pat. No. 4,020,847, discloses a catheter device including a slot having sharp edges extending longitudinally of the catheter to free dangling matter attached inside an artery, which might otherwise obstruct the lumen of the artery.
Hoffman U.S. Pat. Nos. 2,730,101 and 816,552 disclose teat bistoury devices including blades which can be bowed outwardly along the length of each blade to protrude radially. The device is intended to be rotated to cut away restrictions in a milk canal of a cow's teat.
Several prior art devices useful for manually opening venous valves are disclosed in Chin et al. U.S. Pat. Nos. 4,739,760 and 4,768,508 and Reed U.S. Pat. No. 4,655,217. Chin U.S. Pat. No. 4,559,927 discloses an endarterectomy apparatus including a center-pull annular cutter for removing arteriosclerotic material.
Rotary, mechanically operated devices are disclosed in such patents as Sokolik U.S. Pat. No. 3,320,957, which discloses a device including an array of helical stationary blades inside which an oppositelytwisted helical rotor operates to shear material protruding inwardly between the stationary blades. Auth U.S. Pat. No. 4,445,509 discloses a fluted rotary burr. Kensey U.S. Pat. Nos. 4,589,412 and 4,631,052 disclose turbine-driven rotary devices for opening obstructed arteries, and Kensey et al. U.S. Pat. No. 4,681,106 discloses another turbine-driven rotary cutting device.
Several devices for use in retrieving stones from within bodily passageways by entrapping the stones within baskets including arrays of helical wires are disclosed in Grayhack et al. U.S. Pat. No. 4,611,594, Duthoy U.S. Pat. No. 4,625,726, Dormia U.S. Pat. Nos. 4,347,846 and 4,612,931. Related devices are disclosed by McGirr U.S. Pat. No. 4,807,626, and Hawkins, Jr. et al. U.S. Pat. No. 4,790,812, which discloses a parachute-like basket carried on a distal end of a rotatable interior member of a catheter so that the parachute-like basket can retrieve particles cut free by the interior member of the catheter. Park U.S. Pat. No. 3,704,711 discloses a device in which a radially outwardly disposed edge can be controllably concealed within a distal end of a catheter or exposed so that the blade can be used.
Balloon-tipped catheters are disclosed in Fogarty U.S. Pat. No. 3,435,826, while Fogarty U.S. Pat. No. 3,472,230 discloses a catheter including an umbrella-like skirt useful for retrieval of stones.
There still remains a need, however, for an improved atherectomy device which is simple in concept and operation, manually operable, and immediately responsive, and which is useful for all stenoses regardless of the length of the area of stenosis. There is also a particular need for such a device which can be made small enough for surgical removal of plaque from smaller arteries such as those of the heart.
SUMMARY OF THE INVENTION
The present invention overcomes some of the shortcomings and disadvantages of the devices disclosed in the prior art by providing a catheter atherotome which is manually operable and by which a surgeon can carve away atherosclerotic plaque from within an artery by entering the artery with a catheter at a point proximal to the plaque deposit. The plaque is cut away piece by piece, using serial pullback strokes of an expansible and contractible cutter head carried on the distal end of the catheter. The cutter head is collapsible to a constricted configuration providing a small diameter conforming to the diameter of the catheter itself, or expansible to an appropriate size as determined by the size of an artery where it is to be used. The cutter head of the catheter atherotome of the present invention includes at least one blade carrier and at least one support member, all of which are elongate and flexible. The blade carrier and support member or members are aligned generally parallel with each other when the cutter head is in the collapsed configuration, and are arranged about an inner member of the catheter. The inner member extends distally beyond the distal end of an cuter sheath portion of the catheter when the cutter head is in the constricted configuration. Respective ends of each blade carrier and each support member are attached to the inner member and to the outer sheath of the catheter, so that when the distal end of the inner member is moved closer to the distal end of the outer sheath the blade carriers and support members are forced to bow outward, in respective radial planes with respect to the inner member, expanding the cutter head radially to an expanded configuration. When a blade carrier is bowed outward, a sharpened edge of a blade is exposed, directed proximally along the catheter, so that moving the catheter proximally while it is in the expanded configuration brings the sharpened edge to bear against an atherosclerotic plaque deposit to cut it away from the interior of an artery. At least a significant portion of the sharpened edge extends transversely with respect to the length of the catheter, and the inner member and outer sheath of the catheter are prevented from rotating relative to each other, to preserve this orientation of the sharpened edge.
While it is particularly well-adapted for use in the femoral and popliteal arteries, the catheter atherotome of the invention in an appropriate size is also intended for use in the tibial and peroneal arteries and, in smaller size, for use in the heart and renal arteries.
In a preferred embodiment of the invention, the longitudinal position of the inner member of the catheter is adjustable relative to the outer sheath, and the blade carrier and support members are flexible, so that the amount of radial bowing of the elongate members and the degree of exposure of the sharpened edge are controllable. Preferably, the angle of attack of the sharpened edge is adjusted such that it will engage atherosclerotic plaque but not normal arterial lining tissue.
In a preferred embodiment of the invention a single blade carrier and two support members provide a cutting edge over only a minor portion circumference of the cutter head. As a result, atherectomy can be controllably performed on angular sector of the arterial wall in locations such as the femoral artery, where atherosclerosis normally involves only the posterior one half of the artery.
In a preferred embodiment of the invention a flexible membranous sheath is provided to surround the cutter head assembly except where a cutting edge is provided, so that the shavings of plaque are trapped within the cutter head during each cutting pass of the blade over the plaque. This embodiment is intended for use particularly in smaller arteries where it would be awkward or impractical to insert a balloon-tipped catheter beyond a stenosis, or where the catheter atherotome is introduced into an artery percutaneously.
It is, therefore an important object of the present invention to provide an improved catheter atherotome for use in relief of stenoses in arteries.
It is another important object of the present invention to provide such a device which is manually adjustable between a constricted configuration in which a cutting edge is concealed and an expanded configuration in which the cutting edge is operatively positioned and exposed to a degree controllable by the user of the device.
It is an important feature of the apparatus of one embodiment of the present invention that it includes a blade carrier which is flexible, allowing the blade to move between a position in which it moves along the interior of healthy portions of an artery, and a position in which it cuts away atherosclerotic plaque as the cutter head is drawn through a stenosis.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial view of a catheter atherotome which embodies the present invention, with the catheter portion shown foreshortened, and with the cutter head in a constricted configuration.
FIG. 2 is a sectional view of the catheter atherotome shown in FIG. 1, taken along the line 2--2 of FIG. 1.
FIG. 3 is a view similar to FIG. 2, with the cutter head in an expanded, or cutting configuration.
FIG. 4 is a view of the outside of a blade carrier of the cutter head of the atherotome shown in FIGS. 1-3.
FIG. 5 is a side view of the blade carrier shown in FIG. 4.
FIG. 6 is a sectional view, at an enlarged scale, of the blade carrier shown in FIG. 5, taken along line 6--6.
FIG. 7 is a view of the outside of an elongate flexible support member of the cutter head of the atherotome shown in FIGS. 1-3.
FIG. 8 is a side view of the flexible support member shown in FIG. 7.
FIG. 9 is a perspective view, taken in the direction indicated generally by line 9--9 of FIG. 1, showing a fitting for attaching the distal end of each elongate flexible member to the end of the inner member of the catheter atherotome shown in FIGS. 1-3.
FIG. 10 is a perspective view, taken in the direction indicated generally by the line 10--10 in FIG. 1, of the fitting attaching the proximal ends of the elongate flexible members to the distal end of the outer sheath portion of the catheter atherotome shown in FIGS. 1-3.
FIG. 11 is a sectional view of the catheter atherotome shown in FIG. 3, taken along line 11--11 thereof.
FIG. 12 is a pictorial view of the cutter head portion of a catheter atherotome according to the invention, including a plaque-holding membranous sheath portion associated with the blades of the cutter head.
FIG. 13 is a perspective view of a cutter head having a tubular plaque-holding membrane covering the outside of the elongate flexible members.
FIG. 14 is a fragmentary side elevation view showing a detail of the cutter head shown in FIG. 13.
FIGS. 15, 16, and 17 are sectional views of a portion of an artery including a stenosis, showing the action of the cutter head of the catheter atherotome of the present invention as it is drawn past the stenosis to remove a portion of the plaque material forming the stenosis.
FIG. 18 is a view of an alternative form of blade carrier useful in a catheter atherotome according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings which form a part of the disclosure herein, in FIGS. 1-3 a catheter atherotome 10 includes an elongate flexible tubular outer sheath 12. A similar inner member 14 of somewhat greater length is disposed slidably within the of the outer sheath 12. The outer sheath 12 and inner member 14 are flexible enough to negotiate curves in arteries atraumatically, but are rigid enough to maintain relative position between the two, both longitudinally and rotationally. They might be made, for example, of a suitable polyvinyl chloride plastic material, or, possibly of a graphite-fiber-reinforced synthetic plastic resin. Markings 15 may be provided along the outer sheath 12 to indicate the length of the catheter atherotome distal of each marking as an aid to placement in an artery.
A first lever 16 is connected with the outer sheath 12 near its proximal end. A second lever 18 is pivotally connected with the first lever 16 at a pivot point 19. An elongate loop 20 is attached to the second lever 18 and surrounds the rear or proximal end portion 21 of the inner member 14. A stop 22 is fixedly attached to the proximal end of the inner member 14. Finger loops are provided on the levers 16 and 18 for use in manipulation of the first and second levers 16 and 18 to position the proximal end 21 of the inner member 14 relative to the proximal end 23 of the outer sheath 12, as desired. A second stop 24 is preferably also located on the inner member 14, on the distal side of the loop 20, to be used, if necessary, to push the inner member 14 distally into the proximal end 23 of the outer sheath 12. Preferably, a scale 25 is provided on the first lever 16 as an indicator of the position to which the inner member 14 has been withdrawn relative to the outer sheath 12. A cap 26 is mounted on the proximal, or rear end of the outer sheath 12, preferably by means of mating threads, and an 0-ring 28, held in place by the cap 26, grips the exterior surface of the inner member 14 with an appropriately adjustable amount of force to maintain the desired position of the inner member 14 relative to the outer sheath 12.
The inner member 14 is tubular, with a lumen 29 which is large enough to admit passage of a guide wire (not shown) or a balloon-tipped catheter 30 which may, for example, be a Fogarty® arterial embolectomy catheter. However, the lumen may be too small to admit a balloontipped catheter or may be omitted entirely, in an embodiment of the catheter atherotome 10 intended for use in smaller arteries, such as coronary arteries.
A controllably expansible cutter head 32 includes a plurality of elongate flexible members 34 and 35 extending between the distal end 36 of the outer sheath 12 and the distal end 38 of the inner member 14, which extends, as previously mentioned, beyond the distal end 36 of the outer sheath 12. While three elongate flexible members 34 and 35, equiangularly spaced about the inner member 14, are shown and preferred, fewer or more might also be utilized. In the embodiment shown, one of the elongate flexible members is a blade carrier 35, while the remainder are support members 34. The location of the blade carrier 35 with respect to the circumference of the outer sheath 12 and inner member 14 is established as bearing a known relationship to, for example, the attachment of the first lever 16. It would also be possible to have a larger number of blade carriers 35 and a consequently greater angular extent of cutting with each stroke of the atherotome, as will be more fully understood upon consideration of the complete disclosure herein.
The catheter atherotome 10 can be of an appropriate size, depending on the size of the artery in which it is to be used, and larger elongate flexible members 34 and 35 are required for use in larger arteries.
As shown in FIGS. 1 and 2, when the inner member 14 is located with its distal end 38 in a position of maximum extension beyond the distal end 36 of the outer sheath 12, the elongate flexible members 34 and the blade carrier 35 extend closely alongside the protruding portion of the inner member 14, in a generally cylindrical constricted configuration of the cutter head 32, centered about a central longitudinal axis 40.
The elongate flexible support members 34 and the blade carrier 35 are of flexible resilient material such as spring steel sheet material having a midlength portion 42 and a pair of opposite ends 44. The ends 44 are bent into a convex "U" shape and define bores 46 and 47 which pass through the portions forming the legs of the "U" shape at each of the ends 44, as shown in FIGS. 4, 5, 6, 7 and 8. The midlength portion 42 is wider and is also curved, but with a convex outer surface 43 having a greater radius of curvature, as may be seen in FIG. 6, in order to be able to bend more easily than the end portions.
The blade carrier 35 is similar to the support members 34, except that it includes a U-shaped cut defining a blade opening 48 centrally located in the midlength portion 42, leaving a pair of laterally separated, longitudinally extending, lateral portions 50, one on each side of the blade opening 48.
A blade 52, which may be a continuation of the material of the midlength portion 42 of the blade carrier 35, extends from a distally located first end 54 of the blade opening toward a proximal end 58 of the blade opening 48 and resembles generally the shape of a human fingernail. The proximal end 58 of the blade opening is closer to the end -portion 44 of the blade carrier 35 which is attached to the distal end 36 of the outer sheath. The blade 52 has a sharpened edge 60 which extends generally transversely relative to the length of the blade carrier 35 and faces toward the proximal end 58 of the blade opening 48. The sharpened edge 60 preferably includes a central portion 62 which is arcuately curved as seen in a plane perpendicular to the central longitudinal axis 40 of the cutter head 32 (see FIG. 6), but relatively straight as seen looking radially inward toward the cutter head 32 (see FIG. 4). Lateral portions 64 of the sharpened edge 60 are arcuately curved toward the sides of the blade 52, so that when in a cutting position, the blade can excise a strip of plaque from the interior wall of an artery, cutting free the sides of such a strip without tearing the tissue. The sides of the blade, parallel with the lateral portions 50, however, are not sharpened.
Preferably, the sharpened edge 60 is prepared by grinding the outer surface 65 of the blade 52 to taper toward the radially inner surface of the blade. As a result, the sharpened edge 60 is located a small distance radially inward from the extension of the outer surface 43 at the proximal end 58 of the blade opening 48 when the cutter head 32 is in the constricted configuration as shown in FIGS. 1 and 2. Thus, the sharpened edge 60 will not unintentionally cut the interior surface of an artery as the catheter atherotome 10 is being withdrawn.
The catheter 30 extending through the catheter atherotome 10 has a balloon tip 31 which extends beyond the distal end of the catheter atherotome 10, as may be seen in FIG. 1. The catheter 30 is longer than the entire catheter atherotome 10, so that it can be manipulated at the proximal end of the catheter atherotome 10 while extending through the lumen 29 defined within the inner member 14, as shown in FIGS. 2 and 3. Such length is also desirable to provide room for cutting strokes of the atherotome with the ball con tipped catheter 30 located stationary in an artery.
The midlength portions 42 of each elongate flexible member 34, 35 are flexible in response to movement of the inner member 14 relative to the outer sheath 12, so that retraction of the distal end 38 of the inner member with respect to the distal end 36 of the outer sheath results in flexure of the elongate flexible blade carrier 35 and the associated support members 34 of the cutter head 32 to achieve the expanded configuration shown in FIG. 3. The support members 34 and the blade carrier 35 extend to define generally respective radial planes radiating from the central longitudinal axis 40. It will be understood that other forms of construction of the support members 34 and blade carriers 35 besides those described herein are also possible, with the objective being to provide blade carriers and support members which are flexible to provide outward bow-like bending in radial planes. The diameter 66 of the cutter head in its expanded configuration is determined by both the length of each elongate flexible member 34 or 35 and the degree to which the inner member 14 is withdrawn proximally within the distal end 36 of the outer sheath 12.
When the cutter head 32 is adjusted to its expanded configuration the blade carrier 35 bends primarily in the lateral portions 50. The blade 52, attached at the distal end 54 of the blade opening, extends in the direction established by the adjacent material of the blade carrier 35, so that the sharpened edge 60 is exposed in a location radially outside the lateral portions 50.
As may be seen with reference more particularly to FIGS. 9 and 10, as well as to FIGS. 2 and 3, the elongate flexible support members 34 and the blade carrier 35 are prevented from rotating with respect to the inner member 14 and outer sheath 12 by the manner in which they are attached. An articulating mounting ring 68 extends through the bores 46 of all of the several elongate flexible members 34 and 35. The articulating mounting ring 68 is securely attached to a cutter head distal fitting 70, which has an ogival shape. The cutter head distal fitting 70 is attached to the distal end 38 of the inner member 14 by exterior threads defined on the inner member 14 and interior threads in the distal fitting 70 A bore 72 in the distal fitting 70 is an extension of the lumen 29 of the inner member 14.
The articulating mounting ring 68 is attached to the proximal end of the cutter head distal fitting 70 by a plurality of tethering hasps 74 disposed about the proximal end of the distal fitting 70 and equal in number to the number of elongate flexible members 34 and 35 to be attached to the distal fitting 70. Each of the tethering hasps 74 is bent inwardly to form an arch over the articulating mounting ring 68, although some are shown in an unbent condition in FIG. 9. Adjacent ones of the several tethering hasps 74 cooperatively define radially extending slots 76 between one another, with the distal end 44 of a respective one of the elongate flexible members 34 and 35 being disposed within each of the slots 76. The slots 76, bores 46, and articulating mounting rings 68 prevent each of the elongate flexible members 34 and 35 from rotating about an axis parallel with the central longitudinal axis 40, but permit the distal end portion 44 of each elongate flexible member 34, 35 to pivot about the articulating mounting ring 68 as the elongate flexible members 34 and 35 are bowed in respective radial planes with respect to the central longitudinal axis 40.
A proximal cutter head fitting 78 is attached to the distal end 36 of the outer sheath 12 by exterior threads on the fitting 78 mated with interior threads defined in the outer sheath 12. An articulating mounting ring 80, similar to the articulating mounting ring 68, extends through the several bores 47 defined by the proximal end portions 44 of the elongate flexible members 34, 35, interconnecting the proximal ends of all of the elongate flexible members 34, 35 with the proximal fitting 78. The articulating mounting ring 80 is attached to the cutter head proximal fitting 78 by a plurality of tethering hasps 82 equal in number to the total number of elongate flexible members 34 and 35.
Similar to the tethering hasps 74, the tethering hasps 82 extend from the distal face of the cutter head proximal fitting 78 and are bent arcuately inward toward the central longitudinal axis 40 of the catheter atherotome 10, although for clarity some of the hasps are shown unbent in FIG. 10. The hasps 82 are arched over the articulating mounting ring to retain it and the attached proximal end portions 44 of the elongate flexible blade carrier 35 and support members 34. The tethering hasps 82 define radially extending slots 84 between adjacent ones of the hasps 82 and prevent the proximal end portions 44 of the several elongate flexible members 34 and 35 from rotating about an axis parallel with the central longitudinal axis 40 of the catheter atherotome 10. The proximal end portions 44 of the blade carrier 35 and support members 34 are free to pivot about the articulating mounting ring 80 to the expanded position shown, for example, in FIG. 3 in response to retraction of the distal end 38 of the inner member 14 into the distal end 36 of the outer sheath 12.
In order to establish the location and preserve the transverse orientation of the sharpened edge 60, and particularly the central portion 62, the inner member 14 is prevented from rotating within the outer sheath 12 by providing mating non-circular surfaces. For example, as shown in FIG. 11 the inner member 14 may have an avoid cross-section shape, and the proximal fitting 78 may have a corresponding interior surface shape, permitting longitudinal, but not rotational relative movement.
The blade 52 preferably is stiff enough so that the angle of incidence of the sharpened edge 60 is stable, once the amount of flexure of the blade carrier 35 is established. The blade 52 can thus pare off a thin slice of atherosclerotic plaque or similar material from the interior of an artery during use of the catheter atherotome 10 equipped with the cutter head 32 of the invention.
The cutter head 32 provides cutting edge coverage over only a small angular sector of the interior circumference of an artery. The support members 34, being without sharpened edges, slip along the interior surface of the artery and keep the cutter head 32 centered within the arterial lumen.
In some instances, as in coronary arteries, a catheter atherotome may be required to be of a size that is too small to admit passage of the balloon-tipped catheter 30 therethrough. It is still absolutely imperative to retrieve pieces of plaque as they are cut free from the interior wall of an artery. In order to recover the matter excised from an arterial wall, a cutter head 90, shown in FIG. 12, which is otherwise similar to the cutter head 32, additionally includes a flexible membrane in the form of a sheath 92 arranged about and attached to the elongate flexible members 34 and 35. One end of the membranous sheath 92 is attached to the cutter head distal fitting 70 by means of ferrules 94 and the other end is attached to the cutter head proximal fitting 78 by means of ferrules 96. The sheath 92 is preferably adherently attached to the elongate flexible support members 34 and blade carrier 35, at least along their longitudinal margins 98, and a slit 100 or an equivalent opening is provided to expose the sharpened edge 60 and provide ingress for pieces of plaque into the space within the cutter head. Pieces of plaque or the like cut free from the interior wall of an artery are able to pass through the slit 100 in the same manner in which wood shavings pass along the blade of a plane, into the interior of the cutter head 90, to be collected upon retrieval of the catheter atherotome from within an artery.
As shown in FIG. 13, in a cutter head 91 a membranous sheath 93 which is tabular may be used to surround the blade carrier 35 and support members 34 (not shown) which are similar to the corresponding parts of the cutter head 32. The sheath 93 may be attached in the same manner as is the sheath 92.
The membrane material used as the sheath 92 or 93 must be flexible and thin, yet strong and elastic enough to accommodate the adjustment of the cutter head 90 or 91 to its expanded configuration. One suitable material is a thin sheet latex. The membranous sheath 92 or 93 may be attached to distal fitting 70 and the proximal fitting 78 after assembly of the cutter head 90 or 91.
A distal portion 102 of the sheath 92 or 93 may be of a suitable porous material acting as a filter. For example, an expanded polytetrafluoroethylene (PTFE) membrane may be supported on suitable woven material, in order to allow unclotted whole blood to pass through the porous material, while the particles of plaque excised by the cutter head 91 are retained inside the sheath 93, as shown in FIG. 14.
Referring now to FIGS. 15, 16 and 17, showing a portion of an artery 104 including an atheroma 106, the cutter head 32 of the catheter atherotome 10 is illustrated schematically to show its use. As shown in FIG. 15, the catheter atherotome 10 has been inserted into the artery from right to left while the cutter head 32 is in the constricted configuration. Thereafter, the inner member 14 has been withdrawn a distance into the distal end 36 of the outer sheath 12, so that the elongate flexible members 34 and 35 are bowed. This places the midlength portion 42 of each support member 34 at an increased radial distance away from the inner member 14 and similarly causes the blade carrier 35 to carry the blade 52 to a greater radial distance from the inner member 14, and places placing the sharpened edge 60 in an exposed position.
To excise a portion of the atheroma 106, the catheter atherotome is manually pulled to the right as indicated by the arrow 108 in FIG. 16. As the inwardly projecting atheroma 98 is encountered by the blade 52, and particularly by the sharpened edge 60, the sharpened edge 60 begins to cut a portion of the plaque material free, in the form of a thin strip. The convex shape of the outer surface 64 of the blade 52 helps to control the angle of incidence of the sharpened edge 60, to prevent it from digging too deeply and thus cutting through an arterial wall. Where there is no plaque material present, the sharpened edge 60 of the blade 52 is exposed radially outwardly of the outer surface 43 of the blade carrier 35 adjacent the proximal end of the blade opening, but is oriented so that it does not catch the intima of the arterial wall and simply slides along the interior wall of the artery without doing any cutting.
The surgeon using the catheter atherotome 10 can repeatedly move the cutter head 32 back and forth lengthwise of an artery in the area of an atheroma such as the atheroma 108, cutting away a thin, narrow strip of plaque with each movement of the cutter head 32 in the direction indicated by the arrow 100 in FIGS. 12b and 12c, until the lumen of the artery 96 has been opened sufficiently. While it should not usually be necessary, the cutter head 32 can be placed in the constricted configuration during distal movement following a cutting stroke. After each cutting stroke the entire catheter atherotome 10 should be rotated within the artery through an angle about the central axis 40 which can be determined by the position of the levers 16 and 18, so as to result in excision of plaque in an evenly distributed pattern about the interior of the artery. Thereafter, the inner member 14 is returned to its position extended further beyond the distal end 36 of the outer sheath 12, using the loop 20 (see FIG. 1) to push as necessary against the second stop 24, thus retracting the midlength portions 42 of the elongate flexible members 34 and 35 closer to the inner member 14, and returning the cutter head 32 to its constricted configuration. The catheter atherotome 10 can then be withdrawn from the artery, followed by withdrawal of the balloon-tipped catheter 30, with the balloon 60 (see FIG. 1) remaining inflated to retrieve the material which has been cut free from the arterial wall during the process.
An alternative blade carrier 110, useable in place of a blade carrier 35 and shown in FIG. 18, is of an elongate flexible design basically similar to that of the blade carrier 35. It includes a proximal end portion 44a, a midlength portion 42a, and a distal end portion 44b. The end portions are U-shaped, as are the end portions 44 of the blade carrier 35 and support members 34, and define respective bores 46 and 47. The blade carrier 110 has several small blades 112 similar to those of some cheese graters, each blade 112 having an outwardly protruding arcuate sharpened edge 114 facing toward a proximal end portion 44a. An outwardly protruding arcuate throat portion supports each blade 112, and provides a respective opening between the sharpened edge 114 and the adjacent portion of the blade carrier 110. Material cut free by the blades 112 will be directed inwardly through the respective opening into the interior of the cutter head 32 equipped with the blade carrier 110, in the same way as pieces of cheese are directed into a cheese grater.
The catheter atherotome 10 may be introduced into an artery including a stenosis by providing access to the artery and opening the arterial wall at a position more proximal to the heart than the location of the stenosis. Preferably, a guide wire is introduced into the artery and directed past the stenosis. Thereafter, if required, a dilator, such as a dilating balloon catheter, may be introduced into the artery, guided by the wire, and used to dilate the stenosis to a diameter at which it can accept the catheter atherotome 10. The dilator may then be withdrawn and the catheter atherotcme 10 according to the present invention may be inserted into the artery along the guide wire to a position just beyond the stenosis. The guide wire may then be withdrawn and replaced by the balloon-tipped catheter 30. After inflation of the balloon 31 to prevent loss of pieces of material cut free from the arterial wall by the atherotome 10, the cutter head 32 may be expanded to the required size by squeezing together the finger loops of the levers 16 and 18, withdrawing the inner member 14 into the distal end 35 of the outer member 12 a required distance. The elongate loop 20 acts upon the stop 22 to withdraw the proximal end 21 of the inner member 14 at the proximal end of the catheter atherotome 10. Preferably, the scale 25 provided on the lever arm 16 may be used to determine when the inner member 14 has been withdrawn sufficiently to provide the required expansion of the cutter head 32.
Thereupon, the cutter head 32 may be withdrawn past the location of the atheroma, with the sharpened edge 60 of the blade 52 paring away a portion of the plaque from the interior of the artery. The atherotome 10 is then pushed into the artery until the blade 52 is again beyond the atheroma, and is rotated about the central axis 40 to a desired position for a subsequent pull-back cutting stroke, using the levers 16 and 18 as indicators of the amount of rotation of the atherotome 10 within the artery. After several strokes, for example, six to ten cutting strokes, sufficient enlargement cf the lumen of the artery should have taken place, and the cutter head 32 can be returned to its constricted configuration, contracting the flexible support members 34 and blade carrier 35 into position alongside the inner member 14 as shown in FIG. 1, sc that the catheter atherotome 1O can be positioned from the artery with the sharpened edge 60 safely positioned so that it will not harm the lining of the artery.
The procedure is similar when using the catheter atherotome having a cutter head 90 or 91 (FIG. 12), except that the material cut free from the arterial wall would be retained within the membranous sheath 92 for retrieval along with the cutter head 90 or 91 when it is withdrawn from the artery.
The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
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A catheter atherotome and method for its use for performing partial atherectomy in an artery and thereby enlarging the lumen effectively available for blood flow through the artery. An expansible cutter head at the distal end of a catheter includes several elongate flexible members mounted in a parallel array and spaced angularly apart from one another about the associated ends of two concentric members of the catheter in such a way that longitudinal and rotary relative movement of the members of the catheter selectively either bows the flexible members arcuately outwardly into a cutting position or draws them into alignment parallel with the catheter. A sharpened edge of a blade carried on at least one flexible member extends circumferentially and is directed toward the catheter's proximal end when the flexible members are bowed. Partial removal of an atheroma is effected by manually pulling the cutter head past an atheroma with the sharpened edge exposed, with the speed, force, and amount of expansion of the cutter head determined by the operator. Removal of cut-away pieces of atherosclerotic plaque material is accomplished either by pull-back of a balloon-tipped catheter or by use of a membrane enshrouding the cutter head to trap the shavings.
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TECHNICAL FIELD
[0001] The present invention relates to the field of plastic surgery, and in particular, to an implantable biological device for fixation, support and coverage of the breast prosthesis in various surgical operations such as female breast augmentation, breast reconstruction, mammoplasty and breast orthopedics. The invention also relates to a method to manufacture the device.
BACKGROUND OF THE RELATED ART
[0002] Female breast augmentation, breast reconstruction, mammoplasty and breast orthopedics are widely used in patients with breast cancer after surgical resection and people in need of plasty. During the past 20 years, such surgery techniques have been improved greatly. The probability of complications occurring within a short period after the surgery has been significantly decreased. The breast prosthesis has achieved widespread application in breast augmentation and breast reconstruction. However, performing breast augmentation, breast reconstruction, mammoplasty and breast orthopedics by using breast prosthesis could still cause many serious problems during a longer period after the surgery. These problems include the sclerosis of fibrous (scar) tissue encapsulating the prosthesis and the breast distortion, resulting in undesirable aesthetic effects as well as the problems such as discomfort, mastosis and the like. The sclerosis and contraction of the capsule may rupture the aged breast prosthesis over time. Similar problems may occur in about one out of six patients implanted with breast prosthesis.
[0003] The fixation and support of the breast prosthesis mainly depend on autologous tissues of the patient. Due to the gravity of the breast prosthesis and the relaxation of the human tissue, the breast prosthesis may further prolapse or translocate over time and thereby directly affect the aesthetic effect. For patients with the breast resected, the difficulty for breast reconstruction increases due to the lack of support from autologous surrounding tissues of the patients. Autologous breast reconstruction is also referred to the operation of moving the skin, fat or muscle of other autologous regions to the breast of the patients. The tissue required by autologous reconstruction may be collected from abdomen, upper back, upper hip or hip. This type of surgery increases the complexity of surgery. It could introduce additional donor site wounds and damages during tissue collection and result in a longer recovery time and the formation of extra scars. In addition, autologous reconstruction is not suitable for overweighed and smoking patients, and patients with surgical history or circulatory system diseases in the tissue collection region. Furthermore, it is difficult for lean patients to use this method in breast reconstruction since there are insufficient soft tissues in abdomen and back.
[0004] Tissue matrices made from donated human cadaver tissues or from the properly processed animal tissues began to be utilized in recent few years in various surgical operations such as female breast augmentation, breast reconstruction, mammoplasty and breast orthopedics. Since these tissue materials are generally planar membranaceous materials, during the breast reconstruction surgery, surgeons need to tailor the materials into the shapes and sizes according to the situation of surgeries and implants used. The irregular shapes and sizes of the tissue matrices made by the surgeon during surgical operations often do not fit well to the selected breast prosthesis and the surgical region of a patient, resulting in less desirable plastic and cosmetic effect. For example, it is difficult to avoid folding or pleating, to manage the shape of the breast and to achieve a proper projection of the reconstructed breast. Meanwhile, since the materials are expensive and the operations are also error prone for the surgeons to tailor the materials into shapes on the spot via visual inspection when performing the surgeries, the materials could be wasted that increases the surgical costs.
[0005] Therefore, implantable tissue matrix devices for facilitating the fixation, support and coverage of the breast prosthesis in female breast augmentation, breast reconstruction, mammoplasty and breast orthopedics needs to be further developed and improved. The present invention presents the design and the manufacture methods of several kinds of biological devices based on an acellular tissue matrix material. They provide the supporting, fixing and covering materials for the breast prosthesis in various surgical operations such as mammoplasty and breast orthopedics, enabling the doctors to avoid the tailoring of the materials into shapes on the spot during the surgery and therefore to reduce the operation time. In addition, the ptosis and translocation of the breast prosthesis after reconstruction could be avoided so that better plastic and cosmetic effects may be achieved.
CONTENT OF THE INVENTION
[0006] To solve the above problems in the prior art, the first aspect of the present invention proposes a support device for breast prosthesis based on an acellular matrix of a biological tissue and a method for manufacturing the device. This is accomplished by the following technical solutions:
[0007] a support device for breast prosthesis based on a tissue matrix material, wherein the support device for breast prosthesis is constructed by tailoring a membranaceous material into a petal-shaped planar biological matrix blank and then by connecting adjacent edges thereof;
[0008] preferably, wherein the membranaceous material is an acellular tissue material;
[0009] particularly, wherein the number of the petals is 2-5;
[0010] especially, wherein the support device for breast prosthesis is a support device having bowl-shaped or cup-shaped curved surfaces;
[0011] preferably, wherein the petals comprise at least one drainage hole;
[0012] further, wherein the drainage holes are provided in the middle of the connected petals;
[0013] alternatively, wherein the drainage holes are of a single rounded, square, rectangular or triangular shape, or a combination of a plurality of shapes;
[0014] furthermore, wherein each petal has three convex edges;
[0015] further, wherein a support device having bowl-shaped or cup-shaped curved surfaces is constructed by stitching, adhering, laser-welding or radiofrequency-welding of the convex edges between two adjacent petals together;
[0016] optimally, wherein the membranaceous biological planar material has a length of 10-25 cm, and a width of 8-25 cm;
[0017] preferably, wherein the drainage holes are 2-6 mm.
[0018] The second aspect of this invention presents a method for manufacturing the support device described above for breast prosthesis based on the tissue matrix material, wherein the method comprising the steps of:
[0019] (a) preparing a skin tissue, small intestine submucosa, diaphragm, muscle tendon or bladder as a raw material, that is collected from a donated human cadaver or from an animal;
[0020] (b) performing the decellularization, virus inactivation and sterilization of the raw materials obtained from step (a), to produce a membranaceous planar matrix material; or a membranaceous planar matrix material reconstructed from homogenized tissue matrix and/or extracted collagen;
[0021] (c) tailoring the planar matrix material obtained from step (b) into a petal-shaped planar biological matrix blank; and
[0022] (d) connecting adjacent edges of two petals of the planar biological matrix blank obtained in step (c) to form the support device for breast prosthesis;
[0023] preferably, wherein the number of the petal is 2-5;
[0024] especially, wherein the support device for breast prosthesis is a support device having bowl-shaped or cup-shaped curved surfaces.
[0025] further, wherein the petals comprise at least one drainage hole;
[0026] particularly, wherein, the drainage holes are provided in the middle of the connected petals;
[0027] preferably, wherein the drainage holes are of a single rounded, square, rectangular or triangular shape, or a combination of a plurality of shapes;
[0028] wherein, each petal has three convex edges.
[0029] particularly, wherein, a support device having bowl-shaped or cup-shaped curved surfaces is formed by stitching, adhering, laser-welding or radiofrequency-welding of the convex edges between two adjacent petals together.
[0030] preferably, wherein, the membranaceous biological planar material has a length of 10-25 cm, and a width of 8-25 cm;
[0031] further, wherein the size of the drainage holes is 2-6 mm.
[0032] The third aspect of this invention provides a membranaceous biological matrix material which is based on the membranaceous planar matrix material obtained by the second aspect of the present invention.
[0033] By implementing the technical solution described in the above three aspects, the present invention provides a support, fixation and coverage for the breast prosthesis in various surgical operations such as mammoplasty and breast orthopedics, thereby avoids the tailoring of the materials into shapes on the spot by surgeons during the surgery, and reduces the operation time. Meanwhile, the support device of the present invention can match with the breast prosthesis to avoid the ptosis and translocation of the breast prosthesis. Once being implanted, the matrix material of the biological tissues can be integrated into the surrounding breast tissues and transformed into new tissues in the human body without the residues of foreign bodies, thereby achieving ideal plastic and cosmetic effects.
DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 a is a tailored design of a two petal-shaped planar tissue material;
[0035] FIG. 1 b is a biological tissue device for supporting and covering breast prosthesis, having bowl-shaped or cup-shaped curved surfaces, which is constructed by stitching with the two petal-shaped planar tailored design in FIG. 1 a;
[0036] FIG. 2 a is a tailored design of a three petal-shaped planar tissue material;
[0037] FIG. 2 b is a biological tissue device for supporting and covering breast prosthesis, having bowl-shaped or cup-shaped curved surfaces, which is constructed by stitching with the three petal-shaped planar tailored design in FIG. 2 a;
[0038] FIG. 3 a is a tailored design of a four petal-shaped planar tissue material;
[0039] FIG. 3 b is a biological tissue device for supporting and covering breast prosthesis, having bowl-shaped or cup-shaped curved surfaces, which is constructed by stitching with the four petal-shaped planar tailored design in FIG. 3 a;
[0040] FIG. 4 a is a tailored design of a five petal-shaped planar tissue material;
[0041] FIG. 4 b is a biological tissue device for supporting and covering breast prosthesis, having bowl-shaped or cup-shaped curved surfaces, which is constructed by stitching with the five petal-shaped planar tailored design in FIG. 4 a;
[0042] FIG. 5 is an application diagram of the support device for breast prosthesis based on the tissue matrix. (A) a front view after supporting, fixing and covering the breast prosthesis according to the design of the present invention; (B) a lateral view after supporting, fixing and covering the breast prosthesis according to the design of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0043] Hereinafter, the present invention may be further illustrated in detail with reference to accompanying drawings and specific examples.
[0044] The following examples are merely used to illustrate the technical solutions of the present invention more clearly, rather than hereby to limit the protection scope of the present invention.
[0045] The present invention proposes a biological tissue apparatus having bowl-shaped or cup-shaped curved surfaces, which is produced by tailoring and stitching or adhering an acellular tissue matrix material via a specific 2˜5 petal-shaped design, see FIG. 1 to FIG. 4 , wherein the shape of more than 5 petals may also be used to form a biological tissue support device having bowl-shaped or cup-shaped curved surfaces with different specifications, in order to match with the breast prosthesis with various specifications.
[0046] The present invention may also be a planar biological apparatus produced by tailoring a sheet material via a specific 2˜5 (or more than 5) petal-shaped design. The planar biological apparatus is stitched or adhered to a bowl-shaped or cup-shaped apparatus matching with the breast prosthesis with various specifications before use.
[0047] The middle part of each specific petal-shaped design is provided with a plurality of drainage holes, to facilitate the rapid removal of the postoperative fluid. The drainage holes are between 2˜6 mm in size, and can comprise various shapes, such as a rounded, square, rectangular or triangular shape, and the like, and can further comprise a plurality of different shapes at the same time. The drainage holes can also be disposed in other positions of the petals, and there may be different combination modes for the arrangement of size, number and position of the drainage holes.
[0048] In all petal-shaped designs, each petal has three convex edges, and the adjacent convex edges of two petals can be stitched or adhered together to form a curved surface. The size of the petals and the curvature of the convex edges may vary depending on the following factors: the number of the petals specifically as designed, the shape and specification of the breast prosthesis to be matched, and the mode and extent of covering the breast prosthesis.
[0049] The adjacent convex edges between petals can be stitched or adhered together by various methods, and both permanent surgical sutures and degradable surgical sutures can be used. Further, both a single-needle suture method and a continuous suture method can be used. They can be adhered. Adhesion can be performed with various commonly used tissue adhesives (glues), and can also be welded by laser or radiofrequency energy.
[0050] FIG. 1 a shows a two-petal specific design of the present invention, using a retangular tissue matrix having a length A of 10˜25 cm, a width B of 6˜20 cm and a thickness of 0.5˜2.0 mm. The tissue matrix is tailored into two petals having a width of 6˜18 cm and a height of 5˜12 cm. After the adjacent convex edges between the petals being stitched or adhered together, a biological tissue bowl cover or cup cover having a caliber of 5˜15 cm and a height of 4˜10 cm is formed (see FIG. 1 b ), and can support breast prosthesis at sizes between 125 cc and 1250 cc.
[0051] FIG. 2 a shows a three-petal specific design of the present invention, using a square tissue matrix having a length A of 10˜25 cm, a width B of 10˜25 cm and a thickness of 0.5˜2.0 mm. The tissue matrix is tailored into three petals having a width of 6˜20 cm and a height of 5˜18 cm. After the adjacent convex edges between the petals being stitched or adhered together, a biological tissue bowl cover or cup cover having a caliber of 5˜15 cm and a height of 4˜10 cm is formed (see FIG. 2 b ), and can support breast prosthesis at sizes between 125 cc and 1250 cc.
[0052] FIG. 3 a shows a four-petal specific design of the present invention, using a rectangular tissue matrix having a length A of 10˜25 cm, a width B of 8˜20 cm and a thickness of 0.5˜2.0 mm. The tissue matrix is tailored into two kinds of petals having different sizes and shapes, in which two petals have a width of 6˜12 cm and a height of 4˜10 cm, and the other two petals have a width of 5˜10 cm and a height of 5˜12 cm. After the adjacent convex edges between the petals being stitched or adhered together, a biological tissue bowl cover or cup cover having a caliber of 5˜15 cm and a height of 4˜10 cm is formed (see FIG. 3 b ), and can support breast prosthesis at sizes between 125 cc and 1250 cc. In addition, the four-petal specific design of the present invention can also use a rectangular tissue matrix having a length A of 10˜25 cm, a width B of 10˜25 cm and a thickness of mm. The tissue matrix is tailored into four identical petals having a width of 5˜12 cm and a height of 5˜12 cm.
[0053] FIG. 4 a shows a five-petal specific design of the present invention, using a square tissue matrix having a length A of 10˜25 cm, a width B of 15˜25 cm and a thickness of 0.5˜2.0 mm which is tailored into five identical petals having a width of 5˜11 cm and a height of 4˜10 cm. After the adjacent convex edges between the petals being stitched or adhered together, a biological tissue bowl cover or cup cover having a caliber of 5˜15 cm and a height of 4˜10 cm is formed (see FIG. 4 b ), and can support breast prosthesis at sizes between 125 cc and 1250 cc.
[0054] A specific design of at least five petals can also be used in the invention, and is more precise to fit the breast prosthesis, but the difficulty of the production thereof would increase accordingly.
[0055] In various surgical operations such as breast reconstruction, mammoplasty and breast orthopedics, such bowl-shaped or cup-shaped biological tissue apparatus may be fixed at a desired position, and the breast prosthesis is then placed within the bowl cover or cup cover, where the apparatus functions as the support and the cover for the breast prosthesis (see FIG. 5 ) and makes the breast reconstruction having the desirable projection, thereby achieving better aesthetic and cosmetic effects. Once being implanted, the biological tissue device can be integrated with the surrounding breast tissue and remodeled into new tissue in the human body as the tissue matrix is gradually resorbed without the retention of foreign bodies.
[0056] In some breast reconstructions and plastic surgeries, complications may occur that include malposition, malformation, poor coverage, wrinkling, capsule formation and its contraction and the like. The device of the present invention can be used to treat these complications occurring after breast augmentation. For example, the biological tissue device having bowl-shaped or cup-shaped curved surfaces of the present invention can be used to manage the size and position of the implant pocket in front of the chest, as if an internal bra being implanted into the body, in order to better support and maintain the position of the breast prosthesis, thereby reducing the relaxation of the autologous tissues of the patients caused by pressure and tension.
[0057] A membranaceous acellular tissue material for manufacturing the apparatus of the present invention can be a matrix material produced by a series of steps of decellularization, virus inactivation and sterilization from a raw material of a skin tissue, small intestine submucosa, diaphragm, muscle tendon or bladder and the like from donated human cadavers. Also, it can be a matrix material produced by a series of steps of decellularization, immunogenicity reduction, virus inactivation and sterilization using a raw material of a skin tissue, small intestine submucosa, diaphragm, muscle tendon or bladder and the like from pig, bovine, horse or any nonhuman mammal.
[0058] The support device of the present invention can further be produced from a membranaceous material reconstructed from homogenized acellular tissue material and/or extracted collagen.
EXAMPLE 1
[0059] Fresh pericardium was collected from a newly slaughtered bovine. After the attached adipose tissue being stripped manually, the fresh pericardium was temporarily stored in a 0.9% sodium chloride solution and kept in a refrigerator at 4° C. overnight. After being washed in ultrasonic water bath for 30 minutes, the thickness of the pericardium was measured as 0.4˜0.7 mm. Each of 100 g of the pericardium material was decellularized with 1 L of 2% sodium deoxycholate solution (which was dissolved in a buffer solution of hydroxyethylpiperazine-ethanesulfonic acid containing 10 mM ethylenediamine tetraacetic acid, with the pH of 7.4), and shaked and washed in a rotary shaker for 16 hours. The decellularized pericardium was placed in 1 N sodium hydroxide solution to be treated for one hour. The pH was adjusted to be neutral with 10 N hydrochloric acid. Then, it was treated with a 12% sterile sodium chloride solution for 6 hours, and washed with a 0.9% sterile sodium chloride solution for 4 times, each time for 8 hours. The thickness of the pericardium was increased after treatment. The decellularized pericardium is temporarily kept in a refrigerator at 4° C.
EXAMPLE 2
[0060] The decellularized bovine pericardium having a thickness of 0.6˜0.9 mm, a length of 20 cm, and a width of 16 cm was used. The pericardium was tailored into petals with two kinds of different sizes and shapes as shown in FIG. 3 a , in which two petals have a width of 9 cm and a height of 7 cm, and the other two petals have a width of 7 cm and a height of 9 cm. 16 holes having a diameter of 3 mm were perforated in a region where the four petals were connected to each other, with a space between the holes of 1 cm. After the convex edges connected between the petals being stitched with polypropylene sutures together, a flat bowl cover or cup cover of a biological tissue having a caliber of about 9 cm and a height of about 7 cm was formed (see FIG. 3 b ). Once being stitched, it was washed with 0.9% sodium chloride solution; and then was sterilized using 25 kGy gamma ray after being packaged. The device can support breast prosthesis at sizes between 250 cc and 450 cc, and cover about 180 square centimetres of the surface of the breast prosthesis.
EXAMPLE 3
[0061] Fresh porcine hide was collected from a newly slaughtered pig, and after the hide being dehaired manually, the porcine dermis, having a thickness of about 0.8 mm, was separated and cryopreserved at −20° C. After the dermis being thawed, it was soaked in a saline solution containing 100 mg of gentamicin per litre for 4 hours. The porcine dermis was transferred into 0.5% Triton X-100 solution to be decellularized for 20 hours. Then, after being decellularized and washed, it was firstly rinsed with normal saline twice, each time for 120 minutes. After being washed, it was sterilized and virus inactivated with 0.2% peroxyacetic acid for 4 hours. Finally, it was rinsed with a sterile normal saline until no Triton X-100 and enzyme remained. The thickness of the treated derm was increased by about 20%. The treated dermal matrix was temporarily kept in 0.9% sodium chloride solution.
EXAMPLE 4
[0062] A decellularized porcine dermis having a length of 16 cm, a width of 16 cm, and a thickness of 0.9˜1.1 mm was used. It was tailored into three petals having a width of 9 cm and a height of 7 cm as shown in FIG. 2 a . 16 holes having a diameter of 3 mm were perforated in a region where the three petals were connected to each other, with a space between the holes of 1 cm. After the convex edges connected between three petals being stitched with polypropylene sutures together, a flat bowl cover or cup cover of a biological tissue having a caliber of about 9 cm and a height of 5 cm was formed (see FIG. 2 b ). Once being stitched, it was washed with 0.9% sodium chloride solution; and then was sterilized using 25 kGy gamma ray after being packaged. The apparatus can support breast prosthesis at sizes between 250 cc and 350 cc and cover about 150 square centimeters of the surface of the breast prosthesis.
[0063] It should be noted that the above description merely illustrates preferable examples of the present invention, rather than hereby limits the protection scope of the present invention, and the above technical solutions of the present invention may be improved, or replaced with technical equivalents. Therefore, the equivalent structure variations made by using the content of the specification and the drawings of the present invention, and its direct or indirect applications in the other related technical field are encompassed in the scope defined by the present invention.
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The present invention relates to a support device for breast prosthesis based on an acellular matrix material of a biological tissue. The support device for breast prosthesis is formed by tailoring a membranaceous material into a petal-shaped planar biological matrix blank and by connecting adjacent edges thereof. The support device can match with the breast prosthesis; and provide a support, fixation and coverage for the breast prosthesis in various surgical operations such as mammoplasty and breast orthopedics, to avoid the ptosis and translocation of the breast prosthesis, thereby achieving desirable effects of plastic surgery. Once being implanted, the matrix material of a biological tissue can be integrated into the surrounding breast tissue of the subject, and thus transformed into new tissues in human body without the retention of foreign bodies. The present invention further relates to a method for manufacturing a support device, and a membranaceous biological matrix material.
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BACKGROUND
Computers are ubiquitous in today's society. Computer operating speed is related to the speed of the computer's processor. In general, processor speeds increase continually as the industry witnesses an ever increasing growth in the number of transistors per integrated circuit. As processor speeds increase, other devices coupled to the processor also increase their operating speed to gain the full advantage of increased processor speed. Buses, which are used to couple devices together, also increase in speed in order to provide the full advantage of the increased processor speed to the various devices in the system.
Computer companies strive to keep pace with the changing technology trends. In part, this endeavor includes making decisions based on consumer marketing trends as to which new technologies should be offered in the latest computers. However, consumer needs change rapidly as new technology becomes available. For example, a computer company may have already begun production on a computer system that implements a certain configuration of the bus (e.g., PCI-Express™), and midway through production consumer preferences may change so that consumers desire a different bus configuration. At this point in production, valuable market share may be lost if the computer company has to redesign the computer for a different bus. Accordingly, computers that contain the latest technology and are also adaptable to newer technology trends are desirable.
BRIEF SUMMARY
Methods and apparatuses are disclosed for providing a bus in a computer system. In one embodiment, an apparatus comprises: a central processing unit (CPU), a bridge coupled to the CPU, a first slot configured to receive a device, where a first portion of the bridge is coupled to the first slot, a second slot configured to receive a device, where a second portion of the bridge is coupled to the second slot, and where inserting a jumper board into the first slot couples the first portion of the bridge to the second slot.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of various embodiments of the present invention can be obtained when the following detailed description is considered in conjunction with the following drawings, in which:
FIG. 1 illustrates an exemplary computer system;
FIG. 2 illustrates an exemplary serial bus link;
FIG. 3A illustrates an exemplary implementation of a serial bus link;
FIG. 3B illustrates an exemplary system including a jumper board;
FIG. 4 illustrates another exemplary system including multiple jumper boards; and
FIG. 5 illustrates another exemplary system including a jumper board.
DETAILED DESCRIPTION
FIG. 1 illustrates an exemplary computer system 2 . The computer system of FIG. 1 includes a central processing unit (CPU) 10 that couples to a bridge logic device 12 via a system bus (S-BUS). Bridge logic device 12 is referred to as a “North bridge.” Bridge 12 couples to a memory 14 by a memory bus (M-BUS).
Bridge 12 also couples to PCI-Express slots 18 A–B using the PCI-Express™ bus standard as disclosed in “PCI-Express Base Specification 1.0a,” available from the Peripheral Component Interconnect (PCI) Special Interest Group (PCI-SIG) and incorporated herein by reference. Slots 18 A–B may physically reside on the same printed circuit board (also referred to as a “system board” or “mother board”) as CPU 10 . Alternatively slots 18 A–B may be located on a riser or expansion board mounted on the system board. Many desktop computer systems provide ample space on the system board for slots 18 A–B. In a rack mounted computer system however, where real estate on the system board may be limited, slots 18 A–B may reside on a riser board that plugs into the system board. The configuration of slots 18 A–B will be discussed in more detail below.
Additionally, bridge 12 couples to an additional bridge 20 (sometimes referred to as the “South bridge”) using a PCI-Express bus. Bridge 20 is capable of providing for various different busing schemes. For example, bridge 20 couples to PCI-extended (PCI-X) slots 22 A–B using a PCI-X bus and couples to a universal serial bus (USB) connector 24 via a USB. A keyboard 26 may be coupled to system 2 via USB connector 24 . Bridge 20 also couples to a small computer system interconnect (SCSI) controller 16 that in turn connects to SCSI devices like the hard drives.
CPU 10 executes software stored in memory 14 or other storage devices. Under the direction of the software, CPU 10 may accept commands from an operator via keyboard 26 or an alternative input device, and may display desired information to the operator via a display 25 or an alternative output device. Bridge 12 coordinates the flow of data between components such as between CPU 10 and slots 18 A–B.
Memory 14 stores software and data for rapid access and often complements the type of M-BUS implemented. For example, some busing standards use dual data rate (DDR) principles, and therefore memory 14 would then be DDR-compliant. The SCSI device 16 may be a controller that permits connection for additional storage devices to be accessed by system 2 .
Bridge 20 coordinates the flow of data between bridge 12 and the various devices coupled to bridge 20 . For example, signals from the keyboard 26 may be sent along the USB via USB connector 24 to bridge 20 , and from bridge 20 to bridge 12 via the PCI-Express bus.
PCI-Express represents a recent trend in busing schemes to move away from a “shared” bus toward a point-to-point connection. That is, rather than a single parallel data bus through which all data is routed at a set rate (as is the case, for example, for PCI or PCI-X), a PCI-Express-compliant bus comprises a group of point-to-point conductors, in which data is sent serially and all the conductors are individually clocked. Although the focus of some of the Figures involves the PCI-Express bussing standard, other embodiments may include fiber optic and wireless communication links.
FIG. 2 depicts an exemplary system 30 comprising devices 32 A–B communicating with each other serially via a link 34 . Accordingly, system 30 may implement the PCI-Express standard or any other standard capable of performing serial communications. Device 32 A may be a PCI-Express compliant device inserted into slot 18 A. Device 32 B may comprise a bridge that is PCI-Express compliant, such as bridge 12 .
Device 32 A includes a driver or transmitter TX A.1 and device 32 B includes a receiver RX B.1 . The connection between each transmitter and receiver in system 30 comprises a pair of differential signal lines, designated as + and − respectively. Although there are two lines between TX A.1 and RX B.1 carrying differential signals, the difference between the two differential signals yields a single signal of interest with a minimal amount of noise.
As indicated in FIG. 2 by the direction of the arrows, the lines between TX A.1 and RX B.1 communicate information from device 32 A to device 32 B. Similarly, device 32 B communicates information to device 32 A using transmitter TX B.1 and receiver RX A.1 as indicated by the arrows. In this manner, PCI-Express communication between devices 32 A–B is often referred to as a “dual-simplex” because data is sent on one differential pair of data lines (i.e., the + and − lines connecting TX A.1 and RX B.1 ), and data is received on another differential pair of data lines (i.e., the + and − lines connecting TX B.1 and RX A.1 ). The two pairs of data lines that allow information to be conveyed back and forth between devices 32 A–B are often referred to as “lanes.” FIG. 2 shows the link 34 with one lane 36 coupled to transmitters TX A.1 and TX B.1 and also coupled to receivers RX B.1 and RX A.1. Likewise, link 34 includes another lane 37 coupled to transmitters TX A.2 and TX B.2 and also coupled to receivers RX B.2 and RX A.2. Although link 34 includes two lanes 36 – 37 , any number of lanes are possible where the number of lanes contained therein determines the size of the link 34 . For example, link 34 is shown containing the lanes 36 – 37 and therefore the link 34 is referred to as a “by two” link (sometimes denoted as “x2”).
As discussed above with regard to FIG. 1 , bridge 12 may interface to multiple bus technologies and therefore bridge 12 may provide a limited number of PCI-Express links. The actual number and size of the links that bridge 12 implements in practice often depends on industry trends. For example, bridge 12 may be implemented using an integrated circuit with a limited number of pins to support the multiple bus technologies. In order to support the various bus technologies using the limited number of pins, the number of PCI-Express links may be limited. As such, bridge 12 may be configured to provide one link to slots 18 A–B and another link to bridge 20 as indicated in FIG. 1 .
FIG. 3A depicts an exemplary system 40 where the bus or link is bifurcated into portions that are allocated among slots 18 A–B, where marketing trends, customer requirements, or other considerations may indicate how the portions of the link should be allocated. For example, system 40 includes a x8 link with eight lanes numbered 0 – 7 . The eight lanes in the x8 link are bifurcated into portions that are allocated among slots 18 A–B, thereby providing two independent x4 links. Lanes 0 – 3 are routed to the slot 18 B which enables the slot 18 B to be a x4 link. Similarly, lanes 4 – 7 are routed to the slot 18 A which enables the slot 18 A to be a x4 link.
Although slots 18 A–B in system 40 are configured as two x4 links, the physical connectors used to implement slots 18 A–B may be made larger than the size of the link provided to slots 18 A–B in order to support the full x8 input/output (I/O) adapters. That is, despite slots 18 A–B being configured as x4 links, the connectors used to implement slots 18 A–B may be x8 connectors so that each of slots 18 A–B may be capable of supporting a x8 I/O adapters. The PCI-Express specification refers to this as “down shifting.”
Table 1 below illustrates connections for slots 18 A–B. As was illustrated in FIG. 2 with regard to the lanes 36 – 37 , each PCI-Express lane comprises at least four pins, i.e., one set of + and − lines for receiving signals and another set of + and − lines for transmitting signals. Each of the connections referred to in Table 1 are capable of facilitating connection of a lane, and as such, each connection includes at least four pins. However, for sake of discussion, each connection in Table 1 will be referred to as making a single connection to a lane.
Referring to Table 1 and FIG. 3A , lanes 0 – 3 couple to connections 0 – 3 of the slot 18 B respectively. Likewise, lanes 4 – 7 couple to connections 0 – 3 of the slot 18 A respectively. In this manner, the x8 link is allocated so that slots 18 A–B are capable of providing a x4 link to a device that is coupled to the slot 18 B and a x4 link to a device that is coupled to the slot 18 A. Connections 4 – 7 of slots 18 A–B are shown as dashed lines indicating that connections 4 – 7 of slots 18 A–B are not directly coupled to the lanes from the x8 link as described below.
TABLE 1
Connection 0
Connection 1
Connection 2
Connection 3
Slot 18B
Lane 0
Lane 1
Lane 2
Lane 3
Slot 18A
Lane 4
Lane 5
Lane 6
Lane 7
Since slots 18 A–B are configured as x4 links but implemented with x8 connectors, slots 18 A–B are capable of utilizing the maximum capacity by configuring connections 4 – 7 . For example, as shown in FIG. 3A , connections 4 – 7 of the slot 18 A may couple directly to connections 4 – 7 of the slot 18 B using traces 42 . Traces 42 may be implemented on the same printed circuit board as slots 18 A–B, i.e., the system board or a riser card that couples to the system board. Traces 42 may be used to re-route lanes from the x8 link to another slot. For example, by routing lanes 4 – 7 (which couple to connections 0 – 3 of slot 18 A), to connections 4 – 7 of slot 18 A, slot 18 B may be transformed from a x4 link to a x8 link. That is, all of the lanes coming from the x8 link may be re-routed to a single slot. Similarly, by routing lanes 0 – 3 (which couple to connections 0 – 3 of slot 18 B), to connections 4 – 7 of slot 18 B, slot 18 A may be transformed from a x4 link to a x8 link.
FIG. 3B depicts a jumper board 44 that is inserted into slot 18 A, which re-routes the incoming lanes 4 – 7 to traces 42 and thereby enables slot 18 B to provide a full x8 link as explained below. Jumper board 44 includes traces 46 that couple connections 0 – 3 on slot 18 A to connections 4 – 7 on slot 18 A. Traces 46 cross each other, and these crossings are often referred to as “bowites,” which will be described in more detail below. Lanes 4 – 7 directly couple to connections 0 – 3 of slot 18 A (as indicated by the double sided arrow), and then further couple to connections 4 – 7 of slot 18 A via traces 46 . Connections 4 – 7 on slot 18 A are coupled (via traces 42 ) to connections 4 – 7 of slot 18 B, and therefore lanes 4 – 7 are indirectly coupled to connections 4 – 7 of slot 18 B. Accordingly, lanes 0 – 7 of the original x8 link are reconstituted at slot 18 B, allowing slot 18 B to provide a x8 link. Similarly, by inserting the jumper board 44 into slot 18 B, slot 18 A is capable of providing a x8 link.
Although exemplary system 40 depicts a x8 link allocated among slots 18 A–B, other embodiments are possible that implement different sized links. For example, FIG. 4 illustrates and exemplary system 50 including a x24 link that is allocated among three slots 52 A–C. The exemplary system depicted in FIG. 4 is applicable to various serial bussing standards. Slots 52 A–C are implemented using x24 connectors with connections 0 – 23 . Lanes 0 – 7 of the x24 link are coupled to connections 0 – 7 of slot 52 A. Lanes 8 – 15 of the x24 link are coupled to connections 0 – 7 of slot 52 B. Lanes 16 – 23 of the x24 link are coupled to connections 8 – 15 of slot 52 C. In this manner, although slots 52 A–C are implemented using x24 connectors and are therefore capable of providing x24 links, each slot 52 A–C is configured as a x8 link by default. Akin to system 40 , system 50 includes traces 54 A that couple connections 16 – 23 of slot 52 C to connections 16 – 23 of slot 52 A. System 50 also includes traces 54 B that couple connections 8 – 15 of slot 52 B to connections 8 – 15 of slot 52 A.
By inserting jumper boards 56 A and 56 B in slots 52 C and 52 B respectively, slot 52 A is capable of providing a x24 link. More specifically, lanes 16 – 23 of the x24 link (which are directly coupled to connections 8 – 15 of slot 52 C), are coupled to connections 16 – 23 of slot 52 A via jumper board 56 A and traces 54 A. Similarly, lanes 8 – 15 of the x24 link (which are directly coupled to connections 0 – 7 of slot 52 B), are coupled to connections 8 – 15 of slot 52 A via jumper board 56 B and traces 54 B. Consequently slot 52 A is coupled, either directly or indirectly, to lanes 0 – 23 of the x24 link.
System 50 also comprises an auxiliary slot 58 . In some embodiments, Slot 58 is coupled to the x24 link and may be reserved for use by a jumper board. In this manner, any one of slots 52 A–C may be expanded (potentially to the full x24 link) by inserting one of the jumper boards 56 A–B into slot 58 , and therefore expand the ability of slots 52 A–C to provide the full x24 link without consuming one of the slots 52 A–C.
As described above, traces that couple the various slots together as well as the traces present on the jumper boards may cross each other creating what are know as bowties. For example, referring again to FIG. 3B , the traces that connect connections 0 – 3 of slot 18 A to connections 4 – 7 of slot 18 A cross each other and form bowties as indicated. Since the traces are routed on PCBs (i.e., either on a system board or a jumper board), bowtie connections may add to the total number of layers included in the PCB, which adds to PCB complexity and cost. However, by implementing two features of PCI-Express called “lane polarity inversion” and “lane reversal,” crisscrossing of traces may be minimized and the cost and complexity of the system board and the jumper board may be minimized.
With lane polarity inversion, the receiving device (e.g., devices 32 A–B in FIG. 2 ) inverts the data received on the differential signal lines instead of physically crossing the lines on the PCB. That is, a lane will function properly even if a +signal line from the transmitter is connected to the −signal on the receiver and vice versa.
Lane reversal may be thought of as a lane reordering. Effectively, lane reversal allows for the transmitting and receiving devices to reorder which lanes correspond to a particular transmit-receive pair. For example in FIG. 2 , if TX A.1 and RX A.1 on device 32 A are supposed to connect to RX B.2 and TX B.2 on device 32 B respectively, device 32 B may electronically assign RX B.1 and TX B.1 to take the place of RX B.2 and TX B.2 and receive the signals from TX A.1 and RX A.1 .
FIG. 5 illustrates the system shown in FIG. 3B where lane reversal is implemented in lanes 4 – 7 . By reversing the lanes as shown, connection 0 of slot 18 A may be routed to connection 7 of slot 18 . Similarly, connection 1 of slot 18 A may be routed to connection 6 of slot 18 B; connection 2 of slot 18 A may be routed to connection 5 of slot 18 A; and connection 3 of slot 18 A may be routed to connection 4 of slot 18 A. In this manner, the need for traces crossing each other, and thereby creating bowties, is eliminated and the complexity of the jumper board may be reduced. Although lane reversal was shown for lanes 4 – 7 , lanes 0 – 3 may be reversed to reduce the complexity of a jumper board inserted in slot 18 B. In either case, the jumper board may be inserted into either slot 18 A, thereby expanding slot 18 B to a x8 connection, or the jumper board may be inserted into slot 18 B, thereby expanding slot 18 A to a x8 connection.
While various embodiments of the present invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. For example, any size bus may be bifurcated among multiple slots and multiple jumper boards may be used to enable slots to support the full size of the bus. Further, although FIG. 2 discloses differential communication between devices 32 A–B, single ended communication is also possible. In addition, the principles disclosed above are equally applicable to wireless and fiber optic links. For example, referring to FIG. 3B , Lanes 4 – 7 and Lanes 0 – 3 may comprise two portions of a fiber optic link. In this example, traces 42 , which reroute Lanes 4 – 7 from slot 18 A over to slot 18 B, may be implemented using fiber optic lines rather than electrical conductors.
The embodiments described herein are exemplary only, and are not intended to be limiting. Accordingly, the scope of protection is not limited by the description set out above. Each and every claim is incorporated into the specification as an embodiment of the present invention.
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Methods and apparatuses are disclosed for providing a bus in a computer system. In one embodiment, an apparatus comprises: a central processing unit (CPU), a bridge coupled to the CPU, a first slot configured to receive a device, where a first portion of the bridge is coupled to the first slot, a second slot configured to receive a device, where a second portion of the bridge is coupled to the second slot, and where inserting a jumper board into the first slot couples the first portion of the bridge to the second slot.
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This is a division of application Ser. No. 08/037,751, filed Mar. 26, 1993, now U.S. Pat. No. 5,336,454.
FIELD OF THE INVENTION
This invention relates to a ceramic composite and to a method of making ceramic composites having superior erosion and corrosion resistance to molten metal.
BACKGROUND OF THE INVENTION
In the continuous casting of molten steel a break ring is used to provide a thermal barrier at the interface between the furnace nozzle and the mold. The break ring must possess thermal shock resistance, stability at high temperature and must be corrosion and erosion resistant to the high temperature molten steel which flows through the break ring into the mold. The ability to resist attack from the molten metal passing through the break ring as it flows into the extrusion mold determines the tonnage of metal that can be cast in a single operation without interruption of the process to replace the break ring. Cost is another important factor which requires the break ring to be machinable.
Boron nitride is a conventional material used in the fabrication of break rings. It is desirable because of its good thermal shock resistance, stability at high temperature and machinability. However, it lacks good abrasion resistance which subjects it to high wear rates when exposed to flowing molten metal. Boron nitride has also been combined to form a ceramic composite with alumina (Al 2 O 3 ) which is also used in molten metal applications due to its hardness, abrasion resistance and chemical stability. In addition, boron nitride has been separately combined with aluminum nitride (AlN), titanium diboride(TiB 2 ), mullite(3Al 2 O 3 --2SiO 2 ) and with aluminum nitride and titanium diboride. Other materials have also been combined with boron nitride such as silicon nitride to form a composite for use as a break ring. However a silicon nitride composite is not readily machinable. The boron nitride composites BN--AlN, BN--3Al 2 O 3 --2SiO 2 , and BN--TiB 2 --AlN are readily machinable and are commercially available from the Praxair Inc., advanced ceramics division, located in Cleveland, Ohio. The mechanical and physical properties of Al 2 O 3 --BN and mullite-BN composites are described in Lewis et al in "Microstructure and Thermomechanical Properties in Alumina and Mullite Boron Nitride Particulate Ceramic-Ceramic Composites", Ceram. Eng. Sci. Proc. 2: 719-727 (Nos.7-8,1981) which also includes data on the thermal shock resistance of such composites. In addition, U.S. Pat. No. 4,997,605 discloses a hot pressed ceramic composite formed from a blend of fused zirconia mullite and boron nitride which is indicated as having good resistance to thermal shock and reasonably good erosion and corrosion resistance to metal alloys.
The above identified ceramic composites of boron nitride which are readily machinable are all currently formed by hot pressing and have substantially similar corrosion and erosion resistant properties under test conditions which simulate the process conditions of a continuous casting operation. The composite formulation of any of the known boron nitride composites may be adjusted to increase its corrosion and erosion resistance but only as a tradeoff against other properties particularly machinability.
SUMMARY OF INVENTION
In accordance with the present invention it has been discovered that a ceramic composite containing boron nitride, mullite and aluminum nitride, in combination, yields a substantial increase in corrosion and erosion resistance to attack from molten metals which is completely unexpected in comparison to the corrosion and erosion resistance of the known boron nitride composites BN--AlN and BN--3Al 2 O 3 --2SiO 2 as well as that of boron nitride alone. It was further discovered in accordance with the present invention that the a composite containing boron nitride, mullite and aluminum nitride, in combination, is readily machinable and may be fabricated by either hot pressing or cold forming. When formulated in accordance with the present invention the ceramic composite of BN--AlN--3Al 2 O 3 --2SiO 2 has a high resistance to thermal shock and provides superior corrosion/erosion resistance to molten metals relative to the corrosion/erosion resistance of all presently known readily machinable boron nitride composites under similar operating conditions. When the boron nitride composite of the present invention is hot pressed its corrosion and erosion resistance corresponds to a reduction in mass of less than one (1) percent per hour under simulated continuous casting operating conditions. Alternatively, if the ceramic composite BN--AlN--3Al 2 O 3 --2SiO 2 is cold formed in accordance with the present invention its corrosion/erosion resistant properties are as good, comparitively, to the corrosion/erosion properties of known readily machinable hot pressed boron nitride composites.
The ceramic composite of the present invention comprises, in combination, 18.5 to 29.0 weight percent mullite, 35 to 18 weight percent aluminum nitride, balance boron nitride in a minimum concentration of at least about 40 percent by weight.
The present invention is also directed to a method for cold forming a ceramic composite comprising the steps of:
(a) blending a mixture comprising from 18.5 to 29.0 wt % mullite, 35 to 18 wt % aluminum nitride and at least 40 wt % boron nitride;
(b) milling the blend to an average particle size of less than about 5 microns;
(c) coating the particles with a resinous lubricant composed of a vinyl chloride-vinyl acetate resin dissolved in an organic solvent;
(d) compressing the particles into a cold formed shape; and
(e) pressureless sintering the cold formed shape.
Another aspect of the present invention is a method for producing a hot pressed boron nitride ceramic composite comprising the steps of:
(a) blending a mixture comprising from 18.5 to 29 wt % mullite, 35 to 18 wt % aluminum nitride and at least 40 wt % boron nitride;
(b) heating and compressing the blended mixture in a mold at a temperature of between 1650° C. and 1900° C. and at a pressure of between 1800 and 2500 psi; and
(c) cooling the composite at a gradually decreasing pressure so that fracture of the composite is prevented.
DETAILED DESCRIPTION OF THE INVENTION
The ceramic of the present invention is composed of a composite formed from a mixture of the ceramic materials boron nitride(BN), mullite(3Al 2 O 3 --2SiO 2 ), and aluminum nitride (AlN). A densification aid such as CaO should preferably be added to the mixture. Mullite is an orthorhombic homogeneous solid solution of alumina in sillimanite and is commercially available in powder form having an average particle size of less than 10 microns. Boron nitride and aluminum nitride are also commercially available in powder form. Each of the materials in the composite may vary in the following proportion by weight:
______________________________________Material Maximum Range Preferred Range______________________________________CaO 1% to 5% 3.0% to 2.0%AlN 18% to 35% 18.5% to 2943Al.sub.2 O.sub.3 --2SiO.sub.2 30% to 18% 18.5% to 294BN balance 60% to 40%______________________________________
In order to form a homogeneous mixture a portion of the powders should first be preblended in a mixer such as a V-blender using preferably all of the CaO. The preblend should preferably constitute 25% of the total mixture. The other 75% of the preblended mixture should preferably constitute relatively equal amounts of BN,3Al 2 O 3 --2SiO 2 , and AlN. The preblend should then be mixed for at least 30 minutes preferably with an intensifier bar. After the preblend is prepared the V-blender should then be loaded to produce the main blend for the composite in a systematic fashion preferably by layering the V-blender with successive layers of material as is well known to those skilled in the art. The preferred loading of the V-blender in the preparation of the main blend may be carried out as follows:
1. Add substantially 1/2 of the balance of BN.
2. Add substantially 1/6 of the preblend.
3. Add 1/2 of the balance of AlN.
4. Add 1/6 preblend.
5. Add 1/2 balance of 3Al 2 O 3 --2SiO 2 .
6. Add 1/6 preblend.
7. Repeat steps 1-6.
8. The V-blender should be operated for at least 60 minutes preferably with an intensifier bar.
To hot press the material the main powder blend may be added directly to a graphite mold for densification. However, the main powder blend should at first preferably be prepressed into compacts and granulated before being added to the graphite mold. Densification by hot-pressing takes place as a function of temperature and pressure. Hot pressing may be carried out at a temperature of about 1800° C. and a pressure of 2200 psi with a hold time at maximum conditions for two hours. The temperature should rise at a heat rate of typically about 300° C./hour and pressure should be applied gradually reaching full pressure at a temperature of about 1000° C. Pressure can be retained at maximum during cooling to about 1000° C. and should then drop gradually with further cooling. The raw material powders used for both hot pressing and cold forming should have a purity of at least 95% with the boron nitride, mullite and calcium oxide purity of preferably over 97% and with the boron nitride and aluminum nitride of low oxygen concentration. The boron nitride particles should have an average size of less than 1 micron with the other components of the mixture having a particle size of less than 10 microns. Typical properties for the hot pressed composite both with and without calcium oxide is shown in the following two
TABLE I______________________________________A Few Properties of Hot-Pressed BN-AlN-3Al.sub.2 O.sub.3.2SiO.sub.2______________________________________Composition: 55.64% BN-20.93% AIN - 20.93% 3Al.sub.2 O.sub.3.2SiO.sub.2 + 2.5% CaOFabrication: Hot-Pressed 1800° C.-2200 psi, two-hour hold, pressure decayed gradually to 0 at ˜1600° C. and billet ejected into mold taper at 1100° C.______________________________________ Test Sample Direction to Hot-PressingProperties Parallel Perpendicular______________________________________Density, % Theoretical 92.2 92.2Flexure, psi: 25° C. 10,400 15,6001500° C. 4,400 6,500Sonic Modulus, psi × 5.0 8.010.sup.6 : 25° C.CTE, in./inc/°C. × 10.sup.-6 5.2 5.6Thermal Conductivity, 11.0 14.0Watts/M °K.______________________________________Erosion/Corrosion.sup.(1) in Liquid Metalsas Percent Reduction in Diameter ofTest Sample per Hour: Test Sample PercentMetal °C. Reduction Per Hour______________________________________304 Stainless Steel 1535 0.70Low-Carbon Steel 1550 0.17Gray Cast Iron 1480 0Ductile Cast Iron 1480 0______________________________________ (1) Test sample 1/2 in. diameter × 2.0 in. rotating at 60 rpm for exposure time of four hours
TABLE II______________________________________A Few Properties of Hot-Pressed BN-AlN-3Al.sub.2 O.sub.3.2SiO.sub.2(No CaO) Composition: 57.06% BN - 21.47% AlN - 21.47%Mullite______________________________________ Test Sample Direction to Hot- Pressing Parallel Perpendicular______________________________________Density, g/cc 1.70 1.69% Th. 66.93 66.54% Porosity 33.07 33.46Flexure Strength, psi 25° C. 1598 18201500° C. 1874 2130Sonic Modulus, psi × 10.sup.6 0.83 1.08______________________________________Erosion/Corrosion, PercentReduction in Diameter ofTest Sample per Hour% Reduction Metal______________________________________1.66 L.C. Steel (1500° C.)0.27 304 S. S. (1535° C.)0.83 Grey Cast Iron (1480° C.)______________________________________ (1) 1/2 In. Diameter × 2 In. Long Sample, 60 RPM for four hours
A comparison of the corrosion/erosion rate of the composite of the present invention to the corrosion/erosion rate of boron nitride and composites of boron nitride-aluminum nitride and boron nitride-mullite is shown in the following table III:
TABLE III______________________________________Comparison of the Erosion/Corrosion Rate of Commercial BNComposites in Selected Metal Compared to BN InventionComposite Grades Hot-Pressed InventionComponent HBR ALN-60 MBN MBA-Z______________________________________BN 98.0 56.0 50.0 55.64AlN -- 38.0 -- 20.933Al.sub.2 O.sub.3.2SiO.sub.2 -- -- 50.0 20.93CaO -- 6.0 -- 2.5CaF.sub.2 2.0 -- -- --Erosion/corrosion inMolten Metals asPercent Reduction inDiameter of TestSample (1/2 In.Diameter × 2 In. Long)per Hour When Samplesare Exposed to MoltenMetals at 60 RPM forFour Hours:°C.Metals1535 304 Stainless Steel ˜35.0 2.30 3.20 0.701550 Low-Carbon ˜15.0 2.10 2.15 0.14Steel1480 Grey Cast Iron 0.167 -- 0.138 01480 Ductile Cast Iron 0.50 -- 0 0______________________________________
The boron nitride composite of the present invention can be cold formed and pressureless sintered to result in a strong thermally stable stock that offers excellent resistance to molten metals. The preferred cold forming process involves the following steps:
a. Milling the V-blended main blend, which is preferably blended as indicated earlier in connection with hot pressing, to a predetermined average particle size of 3-5 microns (microtrac).
b. Coating the particles with a lubricant of a resin material formed from vinyl chloride and acetate.
c. Cold-forming the particles into the desired shape.
d. Pressureless sintering the cold-pressed article under an inert atmosphere at a temperature of between about 1800° C. and 1975° C., preferably about 1940° C., to produce a strong structure.
The above identified milling step is preferably wet milled in an organic solvent in which the vinyl chloride and vinyl acetate/polyvinyl acetate is dissolved. The preferred solvent is a ketone such as methylethylketone (MEK). By wet milling in a solvent the particles will automatically be coated as indicated above in step "b". Alternatively, the coating could be put on by spray-drying methods. The wet milled powder is dried and crushed to size and screened to an agglomerated size of between -65+325 mesh. The cold forming step "c" can be conducted at pressures such as 35,000 psi in well lubricated metal dies, isostatically molded or slip cast as is well known to those skilled in the art. The cold formed article has a green density of about 55 to 60% theoretical which is substantially uniform throughout its volume. Moreover, if the cold-formed shape is cured at a temperature of about 120° to 160° C., preferably at about 150° C., machining of the product can be readily carried out.
To avoid the formation of cracks in the cold formed product during the step of pressureless sintering the heating of the product should be uniform. This may be accomplished by enclosing but not confining the green shape in a graphite container to permit the formed shape to freely expand or shrink during the heating cycle. Heat rate depends upon cross sectional size of the product but should not exceed about 400° C./hour, preferably about 200° C./hour to about 1900° C. with no more than a 10% temperature drift for about a holding period of 3 hours. The cold formed articles of BN--AlN--3Al 2 O 3 --2SiO 2 -CaO with a composition of 55.64% BN--20.93% APN--20.93% mullite--2.5% CaO bond during pressureless sintering to produce strong machinable stock with densities in excess of 70% of theoretical, and the structure is not substantially wet by liquid 304 stainless steel or low carbon steel. For example, the reduction in the diameter of test samples (1/2 in. diameter×2 in. long) per hour rotating in liquid metal at 60 rpm for four hours are shown below.
______________________________________ Typical Range Reduction Temperature °C.______________________________________304 Stainless Steel 1.6-1.8 1535Low-Carbon Steel 1.6-2.1 1550______________________________________
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A ceramic composition and method for making ceramic composites having superior erosion and corrosion resistance to molten metal. The composite includes mullite, aluminum nitride and boron nitride in combination. The composite may be hot pressed or cold formed and pressureless sintered into a desired shape.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application No. 61/980,677, filed Apr. 17, 2014.
BACKGROUND OF INVENTION
[0002] The present invention relates to sewing. In particular, the invention relates to particular styles of sewing that incorporate decorative stitching such as quilting. A quilt is a type of blanket typically having three layers: a decorative top layer, a middle layer of insulating material, and a backing layer. “Quilting” refers to the technique of joining these layers by stitches or ties.
[0003] Traditional quilting was done by hand and was very labor intensive. The invention of the sewing machine changed that. Quilting evolved from production of functional blankets by specialized artisans into a popular hobby enjoyed by many.
[0004] Modern quilts are typically made using a long-armed sewing machine, or stitcher, attached to a frame. The frame supports and holds the workpiece in place while the sewing machine moves along the frame with respect to the workpiece. A typical quilting apparatus illustrating the relationship between the workpiece, frame, and sewing machine is shown in US Patent Pub. No. 2013/0190916.
[0005] A common way to quilt today is to use what is known as pantograph patterns. Pantographs are a way to “trace” a pre-printed stitch pattern with the machine in order to stitch that pattern onto the fabric. This allows very consistent work to be completed with a much lower skill level required versus traditional hand-guided stitching alone.
[0006] This is normally accomplished by mounting a paper pattern on the rear of the table supporting the frame and workpiece. A laser pointer may be mounted to the stitcher head. The operator may set up the needle/thread at the front of the machine, and operate the stitcher from the rear of the machine. Handles may be provided at the rear of the machine head to allow the operator to move the head from the rear of the table. By “tracing” the paper pattern with the laser dot, the operator is able to reproduce the patterns from the paper template to the fabric being sewn. Normally, these rear handles are mounted on opposing sides of the head. The user grips the handles by reaching “around” the machine.
[0007] FIGS. 1 and 2 are representative of prior art long-armed sewing machine heads 10 . FIG. 1 is a perspective view of a rear portion of a long-armed sewing machine head 10 (hereinafter referred to simply as head 10 ), and FIG. 2 illustrates a rear view of the same head 10 .
[0008] Head 10 may be used in conjunction with a table including frames used to stretch and hold the fabric to be quilted, as taught in US Patent Pub. No. 2013/0190916. FIG. 1 illustrates the rear portion of a head 10 . The other side of head 10 is not illustrated, where the needle and thread are preferably located, and stitching takes place. A laser (not illustrated) may be attached to the top surface of head 10 such that it points downwardly at a table including a pantograph pattern located in front of a quilt on rollers of a table. Thus an operator of a sewing machine similar to head 10 may use handles such as handles 20 to move head 10 such that the dot or other projection produced by the laser traces the pattern of the pantograph in front of the quilt.
[0009] In FIGS. 1 and 2 , handles 20 are mounted on opposing sides of the head 10 . In operation, when an operator is tracing the pantograph pattern with the laser dot, head 10 moves such that it reproduces the same pattern projected by the dot or other projection, ensuring that the needle and thread at the front portion of head 10 is reproducing the pantograph pattern in its stitches on the quilt or other textile. In order to either see the laser dot tracing the pantograph pattern or to see that the needle and thread are functioning properly and generating the correct pattern, an operator must lean to one side or the other of head 10 , which may generate a strain on the operator's neck and/or back.
[0010] Head 10 includes a number of components that are recognizable to those skilled in the art. Head 10 includes cone holders 30 , 35 which preferably may be semi-permanently or permanently mounted to each handle 20 . Cone holders 30 , 35 of the illustrated embodiments are known in the art for holding large cones of thread used in making a quilt (small horizontal spool holders for holding smaller spools of thread are not illustrated). Cone holders 30 , 35 are substantially similarly sized and shaped, and cone holders 30 , 35 are preferably in substantial alignment with one another. Prior art head 10 further includes a back hand wheel 40 for manually raising and lowering the needle. Head 10 also includes a belt guard 50 for shielding fingers, hair, jewelry, and other objects from getting caught in the motor belt. As FIG. 2 illustrates, head 10 may further include a thread guide 60 for controlling thread extending from a large cone of thread associated with cone holder 30 as it extends to the needle associated with the front portion of head 10 . Head 10 may further include other components known throughout the art including a plug for providing power to a mounted laser, thread and tension guides, and light and power switches (not illustrated).
[0011] The conventional handle configuration shown in FIGS. 1 and 2 has several shortcomings. The user is not positioned in an ergonomically optimal position because the configuration of the handles does not allow for the user to stand upright and view the pattern and laser dot directly in front of them. Rather, the user must lean to the left to see the pattern and laser dot. In addition, it is not possible to see the needle during stitching as the user is placed almost directly behind the machine. The location of the handles also necessarily positions the user within close proximity of moving parts of the stitcher, which may pose safety risks.
SUMMARY OF INVENTION
[0012] The present invention relates to a quilting machine, more specifically a long-armed stitching machine, or stitcher. The stitcher includes a sewing head that includes the sewing machine used to quilt fabric. The fabric may be stretched between two rollers of a frame below the stitcher. An operator at the rear portion of the stitcher may steer the head using handles such that a laser associated with the head that points downwardly traces a pantograph pattern located in front of and below the fabric. By tracing the pantograph pattern with the laser, the operator can provide that the needle and thread at the front portion of the head produces the same pattern in front of and below the fabric.
[0013] The stitcher head of the present invention may include an L-shaped arm member that extends from the left side portion of the head, relative to its operator's position, and extends rearwardly toward the operator therefrom. The arm member may also include a projection extending therefrom for mounting a laser to the projection. The laser mounted to the projection may be used to trace a pantograph pattern, thus ensuring that the thread and needle associated with the sewing head produces a substantially similar pattern.
[0014] In other embodiments the laser associated with the head is not mounted to the projection and may be mounted directly to the arm member or elsewhere on the head. In any case, the laser does not interfere with the operation of the head in the quilting process, and the dot or alternative projection generated by the laser used to trace the pantograph pattern is not obstructed.
[0015] The arm member further may include handles attached thereto for steering the sewing head. Any attachment member may be used to selectively engage the handles with the sewing head, but the L-shaped arm member is the preferred attachment member. The handles are preferably offset from the sewing head, preferably adjacent to the left side of the head (when viewed from the rear). Alternatively, the handles may be adjacent to the right side of the head. The head also may include a number of components known throughout the art that are commonly associated with long-arm stitchers.
[0016] The head may include cone holders which may be semi-permanently or permanently mounted to each handle on opposing sides of the head. The cone holders may be of the type known in the art for holding large cones of thread used in making a quilt. The cone holders may be substantially similarly sized and shaped, and the holders may be in substantial alignment with one another. The head may further include a back hand wheel for manually raising and lowering the needle. The head may also include a belt guard for shielding fingers, hair, jewelry, and other objects from getting caught in the motor belt. Moreover, the head may further include a thread guide for controlling thread extending from a large cone of thread associated with a cone holder as it extends to the needle associated with the front portion of the head.
DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views:
[0018] FIG. 1 is a perspective view of a rear portion of a sewing machine head of a long-armed sewing machine with handles mounted on opposing sides of the head.
[0019] FIG. 2 is a rear elevation view of the sewing machine head and associated handles illustrated in FIG. 1 .
[0020] FIG. 3 is a perspective view of a sewing machine head of a long-armed sewing machine with ergonomic handles attached to the head.
[0021] FIG. 4 is a rear elevation view of the sewing machine head and associated ergonomic handles illustrated in FIG. 3 .
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention is directed generally toward a sewing machine and handles associated therewith for operating the sewing machine. FIGS. 3 and 4 illustrate a head 110 that improves upon prior art head 10 . FIG. 3 is a perspective view of the rear portion of head 110 , and FIG. 4 is a rear elevation view of the same. As illustrated in FIGS. 3 and 4 , head 110 may include an attachment member, preferably L-shaped arm member 115 , that extends from the left side portion of head 110 (when viewed from the rear of head 110 ) and extends rearwardly toward an operator therefrom. Arm member 115 may also include a projection member 117 extending therefrom for mounting a laser to projection 117 in a direction away from head 110 . The laser mounted to projection member 117 would be operated in a substantially similar way to that described above for the prior art head 10 . Principally it may be used to trace a pantograph pattern, thus ensuring that the thread and needle associated with head 110 produces a substantially similar pattern. In alternative embodiments, projection member 117 may be positioned and located elsewhere on arm member 115 or head 110 , so long as the laser associated therewith may project a dot or other projection onto a pantograph pattern below the quilt.
[0023] In other alternative embodiments the laser associated with head 110 is not mounted to projection member 117 . It may be mounted directly to arm member 115 or elsewhere on head 110 . The laser may be positioned and located in a plurality of foreseeable locations, so long as it does not interfere with the operation of head 110 in the quilting process, and the projection generated by the laser used to trace the pantograph pattern is not obstructed.
[0024] Arm member 115 further may include handles 120 substantially similar to handles 20 illustrated in FIGS. 1 and 2 . As a result of handles 120 being attached to the arm member 115 , the handles 120 are offset from the head 110 . As an alternative to arm member 115 , other known or foreseeable attachment members may be used to selectively engage head 110 and handles 120 .
[0025] In the illustrated embodiment, handles 120 are positioned adjacent the left side of the head 110 (when viewed from the rear). In an alternative embodiment, a configuration opposite of that illustrated in FIGS. 3 and 4 is envisioned. In that embodiment, arm member 115 would extend from the right side portion of the head 110 , and handles 120 are also positioned adjacent the right side of the head 110 (when viewed from the rear). Such a configuration allows head 110 to be used in a location ergonomically preferable to an operator, which may depend on factors such as pre-existing conditions or right- or left-handedness.
[0026] Head 110 may include many of the same components as head 10 . For example, cone holders 130 and 135 may be semi-permanently or permanently attached on either side of head 110 . As illustrated in FIG. 4 , one cone holder 130 may be attached to arm member 115 adjacent one side portion of head 110 , while another cone holder 135 may be attached to the opposite side including back hand wheel 140 and belt guard 150 may be associated with head 100 . Hand wheel 140 and belt guard 150 may perform substantially the same functions as those described above associated with head 10 .
[0027] Head 110 further may include thread guide 160 . In the illustrated embodiments, thread guide 160 may be positioned and located above cone holder 130 on the left side of rear portion of head 110 . In the alternative embodiment described above, where the handles 120 are positioned adjacent the right side of the head 110 , thread guide 160 may also extend from the right side of head 110 , in a manner substantially similar to that shown in FIGS. 3 and 4 , and described herein above.
[0028] Head 110 may operate in substantially the same manner as head 10 . By using handles 120 to guide head 110 , an operator may trace a laser dot associated with head 110 in one of the manners described herein above to ensure that needle and thread performing the quilting process at the front portion of head 110 is reproducing a pantograph pattern or other reproducible pattern. In the embodiment utilizing head 110 , however, the operator may operate head 110 via handles 120 and confirm that the laser dot is tracing the pantograph pattern, and the needle and thread is functioning accurately without having to lean to one side or the other.
[0029] It should be noted that as an alternative to using a laser to trace a pantograph pattern, a physical pointer may be used instead. For example, a metal or plastic rod may be attached to and project from the handle such that it is positioned and located to physically trace a pantograph pattern to ensure that the needle and thread at the front portion of head 110 are reproducing the pattern. Other known or foreseeable physical means for tracing a pantograph pattern are further envisioned as being able to be used with the present invention. Moreover, digital means of reproducing a pantograph pattern are further envisioned, such as projecting the pattern or reproducing the pattern on a computer or tablet device.
[0030] From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting.
[0031] The constructions described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.
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The present invention relates to a quilting machine and more specifically a long-arm stitching machine, or stitcher. The stitcher includes handles that are used to trace a laser dot on a pantograph pattern located in front of the fabric being quilted. Tracing the laser dot ensures that the needle and thread associated with the sewing machine head duplicates the pattern being traced. In the present invention, the handles are placed to one side of the sewing machine head to allow an operator to remain upright when watching the laser trace the pattern or the needle and thread quilting the fabric.
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This is a divisional of copending application(s) Ser. No. 07/429,876 filed on 10/30/89.
BACKGROUND OF THE INVENTION
i. Technical Field
The present invention relates to an improvement in methods and apparatus for the batch digesting of cellulosic material such as wood chips, and more particularly to a process and apparatus for conserving the sensible heat contained in black spent liquor at the end of a digestion process.
ii. Prior Art
In conventional batch processes for digesting wood chips, the digester is filled with chips and the digester is then charged with a cooking chemical which in a soda process comprises essentially a solution of sodium hydroxide, and in a kraft process, comprises such a solution with a further inclusion of sulfur compound. The digester is then sealed and, with steam, the temperature of the digester is brought up to cooking temperature at which it is maintained for a period of time. At the conclusion of the cook, a blow valve in the digester is opened, and the contents of the digester is discharged into a blow tank by virtue of the hot liquor therein flashing into steam and forcing the delignified pulp out of the digester.
Much of the heat energy acquired by the contents of the digester during the processing exits through the blow tank with exhaust vapors. To recover such heat energy, attempts have been made to pass such vapors through various forms of heat recovery systems. Many of these recovery systems have not been efficient and, to conserve energy costs, some pulp manufacturers have chosen to install continuous digestion processes. A continuous process is quite distinctive from a batch digestion process, but usually has a more efficient utilization of heat than is achieved by a conventional batch process. However, the cost of equipment needed in a continuous process is normally substantially greater than the cost of equipment required in a batch type process, and the characteristics of the pulp obtained may differ.
Various arrangements have been proposed utilizing batch type processes which effect an energy saving such as those proposed in my U.S. Pat. Nos. 4,578,149 and 4,601,787. In the modified batch processes, at the end of a cook, the digester is held under pressure, and displacement liquids are used to displace the hot cooking liquors under pressure and substantially at cooking temperatures. Two or three accumulators are used to store the displaced cool, hot, and warm liquors in the three accumulator systems. During subsequent digester fills, the liquors in the accumulators are pumped to the digester to displace air and to preheat and pretreat the chips. All liquor fills are done by displacement. In the previously known displacement techniques, the displacing fluid is pumped into the bottom of the digester and the displaced fluid flows out the top of the digester.
An object of the present invention is to provide an improved method and apparatus which utilizes the advantages of a batch type process and which effects an increase in thermal energy saving over the more conventional batch processes.
A further object of the invention is to provide an improved batch type digester cooking system which employs a displacement concept of emptying the black spent liquor at the end of the digestion process and which effects a saving in time for removing the liquor at the end of the process.
A still further object of the invention is to provide a process wherein batch type cooking is employed and the black liquor is removed at the end of the cooking process by adding a displacement liquid wherein intermixing of displacement liquid and hot black liquor is diminished in order to conserve the high temperature of the spent liquor.
FEATURES OF THE INVENTION
In accordance with the concepts of the invention, an apparatus and method are employed wherein a digester is filled with wood chips and with cooking liquor, and at the end of the cooking process, the black spent liquor is removed and retained in a reservoir at a high temperature and a superatmospheric pressure and thereafter used to heat and pretreat chips in a second digester to conserve the sensible heat and residual chemicals within the black liquor. The black liquor is removed and transferred to the reservoir under pressure by pumping in a lower temperature displacement liquid both in the bottom and in the top of the digester. The spent high temperature black liquor is removed at a mid-portion of the digester, being pushed out by the two columns of lower temperature liquid approaching from the top and from the bottom. Displacement during subsequent digester fills is handled in a similar manner.
With this arrangement, the displacements are done in a minimum amount of time. At the front of the approaching displacing liquid, where it is pushing the displaced liquid ahead of it, a certain amount of intermixing occurs. The depth of this interface or amount of intermixing is minimal since the distance along which the interface travels is reduced over conventional displacement techniques, and, by pushing the displaced liquid from both directions, the total time required for displacement is reduced. Also, while there are two interfaces between the displaced and the displacing liquids, the depths of the interfaces are reduced.
Another feature resulting from the arrangement of the dual displacement directions is attributable to the reduced cycle time, in that there is an optimum time of cook for the delignification process. When the cooking time has been completed, it is desirable to terminate the cooking reactions quickly, so as to not overcook the wood chips. The reduction in time for displacement by the cooler liquor has a further advantage in that any reduction in time which may be accomplished in the whole process increases the total output capacity of the system in a mill.
Blowing can be accomplished by removal of all of the black liquor and discharging the contents by conventional means such as steam pressure from the top, by utilizing air admitted to the top of the digester to blow the delignified pulp out of the bottom end or, more preferably, by pumping the contents out of the digester.
With displacement liquid being added from both ends, the pulp at both the upper and lower ends receives essentially the same amount of washing in the digester, and, throughout the digester, a greater uniformity in washing within the digester occurs.
Other objects, advantages and features will become more apparent with the teaching of the concepts of the invention in connection with the disclosure of the preferred embodiments in the specification, claims and drawings, in which:
DESCRIPTION OF THE DRAWING
The single Figure of the drawing labeled FIG. 1 is a schematic illustration of a digester system constructed and operating in accordance with the principles of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In a batch type process, it is typical to charge a digester with wood chips, and then introduce into the digester a reactive liquor including a reactive chemical. In the case of the soda process, the reactive liquor known as white liquor is essentially an aqueous solution of liquor which includes a sulfur compound. Digestion occurs with the contents of the digester at elevated temperature and pressure, the temperature within the digester typically being within the range from 330° to 350° F. (165° to 177° C.). At the conclusion of the cooking cycle, the reactive liquor is referred to as black liquor or spent liquor, which is at digester temperature and still contains residual active chemicals.
In accordance with the present invention, at the conclusion of a cooking cycle, and while maintaining the pressure in the digester, a displacement liquid which preferably may be filtrate from a pulp washing cycle, is pumped into both ends of the digester. A first volume of this lower temperature liquid is pumped in to the top and a second volume of lower temperature liquid is pumped into the bottom of the digester to displace the hot black liquor. The hot black liquor leaves the digester through an outlet at the center of the digester, and is passed to a reservoir or accumulator at the temperature and pressure of the digester. Additional displacements may be utilized to further cook and wash the chips. The total volume of each displacement fluid need not equal the black liquor volume. For example, third and fourth volumes pumped into the top and bottom respectively may result in additional hot spent liquor being displaced out of the digester.
When a digester is subsequently filled, chips are added to the digester with suitable packing such as with steam or air nozzles are arranged to emit pressurized fluid against the chips entering the digester. Upon completion of the fill, the digester is pumped hydraulically full of lower temperature washer filtrate typically utilized as a displacement liquid in a previous digester cycle. This fill forces air from the digester, and initially treats and slightly warms the chips. In a three-stage displacement heating process, this fill will be performed with liquor from a cool black liquor accumulator. The cool black liquor is displaced from the digester utilizing warm black liquor from another liquor accumulator, with a following displacement occurring with hot black liquor and thereafter cooking liquors. In each of the displacements, whether at the beginning or at the end of the cooking cycle, the displacing fluid is pumped into both the top and bottom of the digester, with the displaced fluid being removed intermediate the digester ends. Normally, the separate displacements from the top and from the bottom are performed at nearly the same time; however, in some situations it may be desirable to delay one or the other.
In the particular apparatus utilized for carrying out the method of the invention, the drawing shows a digester 10. In the beginning of the digesting cycle, pretreated chips are inserted into the digester at 11 and are packed such as with steam or air for maximum volume. At the lower end of the digester is an opening 12 with a valve 12a which is opened at the completion of the digestion and displacement process for blowing or pumping the pulp into a blow chamber 13.
To begin the cooking process, preliminary heating may be achieved with cool, warm and hot black liquor from a tank farm 16. The tank farm 16 includes a plurality of accumulators. As is well-known to those versed in the art, and as shown in my previously identified U.S. patents, suitable accumulators will be provided for the cool and hot black liquors and perhaps additionally the warm black liquor. Suitable valve control means 17 and 18 are provided so that all displacement liquids are controllably provided at both the top and bottom of the digester. The control means may be typical flow control valves, allowing control of the start, termination and rate of displacement at each end separately. Following completion of the displacements to preheat and pretreat the chips, the chips are subjected to the cooking process, with the digester being sealed and maintained at the predetermined cooking temperature for a predetermined period of time. Additional heating devices such as heat exchangers may be provided as will be recognized by those versed in the art.
At the completion of the cooking cycle, the pressure and temperature within the digester are maintained, and cool displacement liquid is pumped into the top and bottom of the digester, with the low temperature liquid being obtained from a low temperature tank 19 and being forced into the digester by a pump 20 through control lines having valves 21 and 22. As the lower temperature liquid, which is preferably obtained from the pulp washer, is pumped into the digester, it advances upwardly from the bottom and downwardly from the top of digester 10, thereby forcing the hot spent black liquor out through a line and a valve 23 into a high temperature accumulator in the tank farm 16. The high temperature black liquor is used subsequently to preheat chips in another digester as schematically indicated at 27. It will be recognized by those skilled in the art that the digester 27 typically will be similar in size and operation to the digester 10. While separate inlets are shown for the liquids from the low temperature tank 19 and the tank farm 16 at each the top and bottom of the digester, it will be recognized that separate lines with valves from each may use a common inlet in the digester, so that single fluid inlets are provided at the top and at the bottom of the digester.
The digester 10 has a screen 25 at mid-portion between the top and bottom of the digester. The hot black liquor or other fluid displaced in the digester leaves, through screen 25, the screen preventing the escape of pulp. As the displacement liquid progresses in the digester, moving upwardly from the bottom of the digester and moving downwardly from the top toward screen 25 and the displaced liquid leaves, an interface will be formed between the advancing fronts of the displacing liquid, which may be separately collected from the hot spent black liquor. Thus it can be seen that the displacement liquid and displaced liquid are collected and further processed separately with respect to one another.
Blowing of the digester at the completion of the cook may be accomplished by the insertion of pressurized steam, air or other fluid at a top inlet 31. The admission of fluid will continue until all of the pulp has been forced into the blow pit 13. Alternatively, a pump associated with valve 12a and blow pit 13 can be used for evacuating the digester. The fibers in the blow pit will be delivered to a washer 29 which has an admission of wash water 30. The washing liquid, having picked up some heat from the hot fibers is delivered to a low temperature tank 19 to be used as displacement liquid in the next successive batch cooking process. The low temperature tank 19 may be a part of tank farm 16. Usually a plurality of digesters will be used and operated in sequential batch cooking processes, so that the wash liquid from one digester will be used for successive digesters as was the case in using the hot black liquor from the accumulators in the tank farm 16 for successive digesters such as illustrated at 27.
Thus, it will be seen that I have provided an improved and simplified relatively rapidly operating process which is capable of reducing the loss of thermal energy and reducing air pollution by the removal of the black liquor from the pulp before it is blown. Various changes may be made without departing from the scope of the present invention.
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An apparatus and method for use in a batch digesting process to quantitatively displace fluids in the digester by pumping into the digester under pressure a first volume of displacing fluid at the upper end and a second volume of displacing fluid at the lower end of the digester. Displaced fluids are collected and removed form the digester near the midline between the top and the bottom of the digester.
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CROSS-REFERENCES TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C 119(a) to Chinese Application No. 200810056545.9, filed on Jan. 21, 2008, in the Chinese intellectual property Office, and Chinese Application No. 200810056896.X, filed on Jan. 25, 2008, in the Chinese intellectual property office, each of which is incorporated herein by reference in its entirety set forth in full. The present application is a divisional application of U.S. patent application Ser. No. 12/273,630, filed on Nov. 19, 2008 now U.S. Pat. No. 7,884,891, in the USPTO.
FIELD OF THE INVENTION
The present invention relates to a thin film transistor liquid crystal display (TFT-LCD).
BACKGROUND OF THE INVENTION
TFT-LCDs have advantages of small size, low power consumption, low radiation, etc. TFT-LCDs developed fast in recent years and can offer better display performance with increase in size of display panel. In TFT-LCDs, a normal white driving mode is always adopted, in which a black image is displayed when a voltage is applied to pixel electrodes and the panel is transparent for light when no voltage is applied.
FIG. 9 is an equivalent circuit diagram of a conventional TFT-LCD. As shown in FIG. 9 , when the thin film transistor (TFT) as a switching element of each pixel is turned on, the data signal is transmitted to the pixel electrode of the pixel via the TFT. The voltage applied on the pixel electrode controls the orientation of the liquid crystal molecules in the liquid crystal cell so as to control the light passage. During scanning in one frame, the pixel voltage is maintained through a storage capacitor formed by the pixel electrode and a pixel common electrode line. That is, the pixel voltage is maintained by the storage capacitor (Cst) formed with the pixel common electrode line (Cst on Common). In the operation of the TFT-LCD, the TFTs are turned on in sequence, and data signals are introduced into the pixels in sequence. When the gate line in the nth row is applied with a high voltage (Vgh) and the TFTs in the nth row are turned on, the gate lines in remaining rows are applied with a low voltage signal (Vgl) so that the TFTs in these rows are turned off and the voltage of the pixels in these rows can be maintained with Cst.
FIG. 10 is an equivalent circuit diagram of the design of Cst on Common. A plurality of gate lines 1 and a plurality of data lines 2 intersect with each other to define a plurality of pixels, and each pixel has a pixel electrode 5 formed therein. For each pixel, the gate line, the data line, and the pixel electrode are interconnected with a three-terminal switching element, that is, a pixel TFT 6 . A plurality of pixel common electrode lines 4 are provided for forming storage capacitors, and the pixel common electrode lines 4 are parallel to the gate lines 1 and partially overlap with the pixel electrodes 5 in each row. The pixel common electrode lines 4 are directly connected with a common electrode line 3 in the periphery region of the panel. Therefore, in operation, no matter whether the pixel is turned on, a same voltage is applied to the pixel common electrode line for forming the Cst. After the pixel electrode 5 is charged, the voltage applied on the pixel electrode (data) is maintained until the pixel is recharged in the next frame. When the next frame of image is coming, the image data is refreshed based on the current image. That is, after pixels in the nth row have been turned on and before pixels in the (n+1)th row are turned on, the original display information in the pixels in the (n+1)th row cannot be cleared in time, which causes visual residual and tailing of a motion picture. Thus, the conventional TFT-LCD modifies an existing image to display a new one, which causes visual residual and tailing of a motion picture and also renders a response speed and display quality degraded.
In addition, the gate signal applied on the gate line suffers from delay in transmission, which requires that the resistance of the gate line should be within a certain range, i.e., the line width should be controlled within a range. In design, shading strips are provided on a color filter substrate to shelter the gate line and the pixel common electrode line. Therefore, line width influences aperture ratio of a pixel, and in turn aperture ratio directly affects the ratio of light passing the pixel. If the aperture ratio is larger, the ratio of light passing the pixel is higher. Therefore, in the conventional TFT-LCD, increasing the line width of gate line to reduce signal delay on the gate line conflicts with increasing the aperture ratio of the pixel, and a compromise is needed between a large line width and a large aperture ratio.
SUMMARY OF THE INVENTION
One embodiment of the present invention provides a thin film transistor liquid crystal display (TFT-LCD) comprising: a peripheral common electrode line for providing a constant voltage; a plurality of pixel common electrode lines for maintaining a constant voltage; a plurality of gate lines for providing gate signals; a plurality of data lines for providing data signals, which intersect the gate lines to define a plurality of pixels in rows; a plurality of pixel electrodes, which are formed in the respective pixels and overlap with the respective pixel common electrode lines to form storage capacitors; a plurality of first thin film transistors (TFTs), for each of which, a gate and a source is connected with the gate line in the previous row, and a drain is connected with the pixel common electrode line in a same row; and a plurality of second TFTs, for each of which, a gate is connected with the gate line in the same row, a source is connected with the peripheral common electrode line, and a drain is connected with the pixel common electrode line in the same row.
Another embodiment of the present invention provides a thin film transistor liquid crystal display (TFT-LCD) comprising: a peripheral common electrode line for providing a constant voltage; a plurality of pixel common electrode lines for maintaining a constant voltage; a plurality of gate lines for providing gate signals; a plurality of data lines for providing data signals, which intersect the gate lines to define a plurality of pixels in rows; a plurality of first thin film transistors (TFTs), through one of which an end of one gate line is connected with one pixel common electrode line in a row next to the one gate line; a plurality of second TFTs, through one of which the peripheral common electrode line is connected with an end of the one pixel common electrode line; a plurality of third TFTs, through one of which the other end of the one pixel common electrode line is connected with the peripheral common electrode line; and a plurality of fourth TFTs, through one of which the other end of the one gate line is connected with the other end of the one pixel common electrode line in the row next to the gate line.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein:
FIG. 1 is an equivalent circuit diagram of a TFT-LCD according to a first embodiment of the present invention;
FIG. 2 is an equivalent circuit diagram of a TFT-LCD according to a second embodiment of the present invention;
FIG. 3 is an equivalent circuit diagram of a TFT-LCD according to a third embodiment of the present invention;
FIG. 4 is an equivalent circuit diagram of a TFT-LCD according to a fourth embodiment of the present invention;
FIG. 5 is an equivalent circuit diagram of a TFT-LCD according to a fifth embodiment of the present invention;
FIG. 6 is an equivalent circuit diagram of a TFT-LCD according to a sixth embodiment of the present invention;
FIG. 7 is an equivalent circuit diagram of a TFT-LCD according to a seventh embodiment of the present invention;
FIG. 8 is an equivalent circuit diagram of a TFT-LCD according to an eighth embodiment of the present invention;
FIG. 9 is an equivalent circuit diagram of a conventional TFT-LCD; and
FIG. 10 is an equivalent circuit diagram of the design of Cst on Common in a conventional TFT-LCD.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in detail below with reference to the accompanying drawings and the embodiments.
In the following embodiments, a first end refers to the end of the lines near the gate driver 7 on a panel, and a second end refers to the end of the lines away from the gate driver 7 on the panel.
First Embodiment
FIG. 1 is an equivalent circuit diagram of a TFT-LCD according to the first embodiment of the present invention. As shown in FIG. 1 , the TFT-LCD comprises: a peripheral common electrode line 3 for providing a constant voltage; a plurality of pixel common electrode lines 4 for maintaining a constant voltage; a plurality of gate lines 1 for providing gate signals; a plurality of data lines 2 for providing data signals, which intersect the gate lines 1 to define a plurality of pixels in rows; a plurality of pixel electrodes 5 , each of which is provided in each pixel between one adjacent gate line 1 and one adjacent data line 2 , is connected with, for example, the drain of a pixel TFT 6 as a switching element, and overlaps with the pixel common electrode line 4 in the same row to form a storage capacitor; a plurality of first TFTs 11 , for each of which, the gate and the source is connected with the first end of the respective gate line 1 in the previous row, and the drain is connected with the first end of the pixel common electrode line 4 in the same row; and a plurality of second TFTs 12 , for each of which, the gate is connected with the first end of the gate line 1 in the same row, the source is connected with the peripheral common electrode line 3 , and the drain is connected with the first end of the pixel common electrode line 4 in the same row. In drawings, a gate driver 7 for controlling the gate lines is provided on the left side on a panel, and a data driver 8 for controlling the data lines is provided on the upper side on the panel, but this arrangement is not limitative.
The following description is made with reference to the (n−1)th, nth, and (n+1)th rows of the pixels on the panel. When the nth row is turned on, i.e., the nth row gate line 1 is applied with a high voltage signal (Vgh), the nth row pixel electrodes 5 are applied with the data signals transmitted from the data lines 2 . The remaining rows are controlled by a low voltage signal (Vgl), so that the nth row first TFT 11 is turned off, while the nth row second TFT 12 is in operation. Therefore, the pixel common electrode line 4 in the nth row for forming the storage capacitor (Cst) is applied with a common voltage via the nth row second TFT 12 , so that the nth row pixels can be charged normally and are in operation. At the same time, the (n+1)th first TFT 11 is turned on, i.e., the pixel common electrode line 4 in the (n+1)th row for forming storage capacitor (Cst) is also applied with the high voltage signal (Vgh). That is, when the nth row is in operation, the nth row gate line applies in advance a high voltage to the pixel common electrode line 4 of the storage capacitor (Cst) in the (n+1)th row before the (n+1)th row is turned on. As a result, a black image is displayed before the (n+1)th row is turned on, and motion blur can be alleviated.
According to the present embodiment, the LCD display is driven by inserting black data row by row, so that the image in a row can be cleared, i.e., the gray image is reset to a black image, before the image in the row is refreshed. In this way, the tailing caused by visual residual can be eliminated.
Second Embodiment
FIG. 2 is an equivalent circuit diagram of the TFT-LCD according to the second embodiment of the present invention. As shown in FIG. 2 , the second embodiment differs from the first embodiment in that the TFT-LCD further comprises a plurality of third TFTs 13 . For each of the third TFTs 13 , the gate is connected with the second end of the gate line 1 in the same row, the source is connected with the peripheral common electrode line 3 , and the drain is connected with the second end of the pixel common electrode line 4 in the same row. The second TFTs 12 and the third TFTs 13 have the same function.
The following description is made with reference to the (n−1)th, nth, and (n+1)th rows of the pixels. When the nth row is turned on, i.e., the gate line 1 in the nth row is applied with a high voltage signal (Vgh), the nth row pixel electrodes 5 are applied with the data signal transmitted from the data lines 2 . The remaining rows are controlled by a low voltage signal (Vgl), so that the nth row first TFT 11 is turned off, and the nth row second TFT 12 and the nth row third TFT 13 are in operation. Therefore, the pixel common electrode line 4 of the nth row storage capacitor (Cst) is applied with a common voltage from the peripheral common electrode line 3 via the nth row second TFT 12 and the nth row third TFT 13 , so that the nth row pixels can be charged normally and are in operation. At the same time, the (n+1)th first TFT 11 is turned on, i.e., the pixel common electrode line 4 of the (n+1)th row storage capacitor (Cst) is also applied with the high voltage signal (Vgh). That is, when the nth row is in operation, the nth row gate line 1 applies in advance a high voltage to the pixel common electrode line 4 of the storage capacitor (Cst) in the (n+1)th row before the (n+1)th row is turned on. As a result, a black image is displayed before the (n+1)th row pixel is turned on, and motion blur can be alleviated.
According to the embodiment of the present invention, the LCD display is driven by inserting black data row by row, so that the image in a row can be cleared, i.e., the gray image is reset to a black image, before the image in the row is refreshed. In this way, the tailing caused by visual residual can be eliminated.
Third Embodiment
FIG. 3 is an equivalent circuit diagram of the TFT-LCD according to the third embodiment of the present invention. As shown in FIG. 3 , the third embodiment differs from the first embodiment in that the TFT-LCD further comprises a plurality of fourth TFTs 14 . For each of the fourth TFTs 14 , the gate and the source are connected with the second end of the gate line 1 in the previous row, and the drain is connected with the second end of the pixel common electrode line 4 in the same row. The first TFTs 11 and the fourth TFTs 14 have the same function.
The following description is made with reference to the (n−1)th, nth, and (n+1)th rows of the pixels. When the nth row is turned on, i.e., the gate line 1 in the nth row is applied with a high voltage signal (Vgh), the nth row pixel electrodes 5 are applied with the data signal transmitted from the data lines 2 . The remaining rows are controlled by a low voltage signal (Vgl), so that the nth row first TFT 11 and fourth TFT 14 are turned off, and the nth row second TFT 12 is in operation. Therefore, the pixel common electrode line 4 of the nth row storage capacitor (Cst) is applied with a common voltage from the peripheral common electrode line 3 via the second TFT 12 , so that the nth row pixels can be charged normally and are in operation. At the same time, the (n+1)th first TFT 11 and fourth TFT 14 are turned on, i.e., the pixel common electrode line 4 of the (n+1)th row storage capacitor (Cst) is also applied with the high voltage signal (Vgh). That is, when the nth row is in operation, the nth row applies in advance a high voltage to the pixel common electrode line 4 of the storage capacitor (Cst) in the (n+1)th row before the (n+1)th row is turned on. As a result, a black image is displayed before the (n+1)th row pixel is turned on, and motion blur can be alleviated.
According to the embodiments of the present invention, the LCD display is driven by inserting black data row by row, so that the image in a row can be cleared, i.e., the gray image is reset to a black image, before the image in the row is refreshed. In this way, the tailing caused by visual residual can be eliminated.
Fourth Embodiment
FIG. 4 is an equivalent circuit diagram of the TFT-LCD according to the fourth embodiment of the present invention. As shown in FIG. 4 , the fourth embodiment differs from the first embodiment in that the TFT-LCD further comprises a plurality of third TFTs 13 and a plurality of fourth TFTs 14 . For each of the third TFTs 13 , the gate is connected with the second end of the gate line 1 in the same row, the source is connected with the peripheral common electrode line 3 , and the drain is connected with the second end of the pixel common electrode line 4 in the same row. For each of the fourth TFTs 14 , the gate and the source are connected with the second end of the gate line 1 in the previous row, and the drain is connected with the second end of the pixel common electrode line 4 in the same row. The first TFTs 11 and the fourth TFTs 14 have the same function, and the second TFTs 12 and the third TFTs 13 have the same function.
The following description is made with reference to the (n−1)th, nth, and (n+1)th rows of the pixels. When the nth row is turned on, i.e., the gate line 1 in the nth row is applied with a high voltage signal (Vgh), the nth row pixel electrodes 5 are applied with the data signal transmitted from the data line 2 . The remaining rows are controlled by a low voltage signal (Vgl), so that the nth row first TFT 11 and fourth TFT 14 are turned off, and the nth row second TFT 12 and third TFT 13 are in operation. Therefore, the pixel common electrode line 4 of the nth row storage capacitor (Cst) is applied with a common voltage from the peripheral common electrode line 3 via the second TFT 12 and the third TFT 13 , so that the nth row pixels can be charged normally and are in operation. At the same time, the (n+1)th first TFT 11 and fourth TFT 14 are turned on, i.e., the pixel common electrode line 4 of the (n+1)th row storage capacitor (Cst) is also applied with the high voltage signal (Vgh). That is, when the nth row is in operation, the nth row applies in advance a high voltage to the pixel common electrode line 4 of the storage capacitor (Cst) in the (n+1)th row before the (n+1)th row is turned on. As a result, a black image is displayed before the (n+1)th row pixel is turned on, and motion blur can be alleviated.
According to the embodiment of the present invention, the LCD display is driven by inserting black data row by row, so that the image in a row can be cleared, i.e., the gray image is reset to a black image, before the image in the row is refreshed. In this way, the tailing caused by visual residual can be eliminated.
Fifth Embodiment
FIG. 5 is an equivalent circuit diagram of a TFT-LCD according to the fifth embodiment of the present invention. As shown in FIG. 5 , the TFT-LCD comprises: a peripheral common electrode line 3 for providing a constant voltage; a plurality of pixel common electrode lines 4 for maintaining a constant voltage; a plurality of gate lines 1 for providing gate signals; a plurality of data lines 2 for providing data signals, which intersect the gate lines 1 to define a plurality of pixels in rows; a plurality of pixel electrodes 5 , each of which is formed in a pixel between one adjacent gate line 1 and one adjacent data line 2 , is connected with the drain of a pixel TFT 6 , and overlaps with the pixel common electrode line 4 in the same row to form a storage capacitor; a plurality of first TFTs 11 , for each of which, the gate and the source is connected with the first end of the gate line 1 in the previous row, and the drain is connected with the first end of the pixel common electrode line 4 in the same row; a plurality of third TFTs 13 , for each of which, the gate is connected with the second end of the gate line 1 in the same row, the source is connected with the peripheral common electrode line 3 , and the drain is connected with the second end of the pixel common electrode line 4 in the same row.
The following description is made with reference to the (n−1)th, nth, and (n+1)th rows of the pixels. When the nth row is turned on, the nth row first TFT 11 is turned off, and the nth row third TFT 13 is in operation. Therefore, the pixel common electrode line 4 of the nth row storage capacitor (Cst) is applied with a common voltage via the third TFT 13 , so that the nth row pixels can be charged normally and are in operation. At the same time, the (n+1)th first TFT 11 is turned on, i.e., the pixel common electrode line 4 of the (n+1)th row storage capacitor (Cst) is also applied with the high voltage signal (Vgh). That is, when the nth row is in operation, the nth row applies in advance a high voltage to the pixel common electrode line 4 of the storage capacitor (Cst) in the (n+1)th row before the (n+1)th row is turned on. As a result, a black image is displayed before the (n+1)th row pixel is turned on, and motion blur can be alleviated.
Sixth Embodiment
FIG. 6 is an equivalent circuit diagram of a TFT-LCD according to the sixth embodiment of the present invention. As shown in FIG. 6 , the TFT-LCD comprises: a peripheral common electrode line 3 for providing a constant voltage; a plurality of pixel common electrode lines 4 for maintaining a constant voltage; a plurality of gate lines 1 for providing gate signals; a plurality of data lines 2 for providing data signals, which intersect the gate lines defining a plurality of pixels; a plurality of pixel electrodes 5 , each of which is formed in a pixel between one adjacent gate line 1 and one adjacent data line 2 , is connected with the drain of a pixel TFT 6 , and overlaps with the pixel common electrode line 4 in the same row to form a storage capacitor; a plurality of second TFTs 12 , for each of which, the gate is connected with the first end of the gate line 1 in the same row, the source is connected with the peripheral common electrode line 3 , and the drain is connected with the first end of the pixel common electrode line 4 in the same row; a plurality of fourth TFTs 14 , for each of which, the gate and the source are connected with the second end of the gate line 1 in the previous row, and the drain is connected with the second end of the pixel common electrode line 4 in the same row.
The following description is made with reference to the (n−1)th, nth, and (n+1)th rows of the pixels. When the nth row is turned on, the nth row fourth TFT 14 is turned off, and the nth row second TFT 12 is in operation. Therefore, the pixel common electrode line 4 of the nth row storage capacitor (Cst) is applied with a common voltage via the second TFT 12 , so that the nth row pixels can be charged normally and are in operation. At the same time, the (n+1)th fourth TFT 14 is turned on, i.e., the pixel common electrode line 4 of the (n+1)th row storage capacitor (Cst) is also applied with the high voltage signal (Vgh). That is, when the nth row is in operation, the nth row applies in advance a high voltage to the pixel common electrode line 4 of the storage capacitor (Cst) in the (n+1)th row before the (n+1)th row is turned on. As a result, a black image is displayed before the (n+1)th row pixel is turned on, and motion blur can be alleviated.
Seventh Embodiment
FIG. 7 is an equivalent circuit diagram of the TFT-LCD according to the seventh embodiment of the present invention. As shown in FIG. 7 , the seventh embodiment differs from the fourth embodiment in that the driving device comprises the third TFTs 13 and the fourth TFTs 14 instead of the first TFTs 11 and the second TFTs 12 in the first embodiment. Similarly, the image in a row can be cleared, i.e., the gray image is reset to a black image, before the image in the row is refreshed. In this way, the tailing caused by visual residual can be alleviated. However, since the third TFTs 13 and the fourth TFTs 14 are away from the gate driver 7 , signal delay may be caused with the increase of the line distance of the pixel common electrode line 4 . Although the flickering of image may occur, the technical solution in this embodiment can work to reduce motion blur.
Eighth Embodiment
As shown in FIG. 8 , the TFT-LCD of the present embodiment comprises: a peripheral common electrode line 3 for providing a constant voltage; a plurality of pixel common electrode lines 4 for maintaining a constant voltage; a plurality of gate lines 1 for providing gate signals; a plurality of data lines 2 intersecting with the gate lines 1 to define a plurality of pixels in rows; a plurality of first TFTs 11 , through one of which an end of one gate line 1 is connected with one pixel common electrode line 4 in the row next to the gate line 1 ; a plurality of second TFTs 12 , through one of which the peripheral common electrode line 3 is connected with an end of the pixel common electrode line 4 ; a plurality of third TFTs 13 , through one of which the peripheral common electrode line 3 is connected with the other end of the pixel common electrode line 4 ; and a plurality of fourth TFTs 14 , through one of which the other end of the gate line 1 is connected with the other end of the pixel common electrode line 4 in the row next to the gate line 1 .
As shown in FIG. 8 , in the present embodiment, the gate and the source of the first TFT 11 are connected with one gate line 1 , the drain of the first TFT 11 is connected with the pixel common electrode line 4 in the row next to the gate line 1 ; the gate and the source of the second TFT 12 are connected with the peripheral common electrode line 3 , the drain of the second TFT 12 is connected with the pixel common electrode line 4 . Further in this embodiment, the gate and the source of the third TFT 13 are connected with the peripheral common electrode line 3 , the drain of the third TFT 13 is connected with the other end of the pixel common electrode line 4 ; the gate and the source of the fourth TFT 14 are connected with the other end of the gate line 1 , the drain of the fourth TFT 14 is connected with the other end of the pixel common electrode line 4 in the row next to the gate line 1 .
The following description is made with reference to the (n−1)th, nth, and (n+1)th rows of the pixels. When the (n−1)th row gate line 1 is applied with a high voltage signal (Vgh) and is turned on, the nth row first TFT 11 is turned on. At the same time, the same high voltage signal (Vgh) is applied to the pixel common electrode line of the nth row storage capacitor (Cst), and this signal is transmitted to the rightmost side of the panel together with the signal on the gate line 1 . The fourth TFT 14 is also turned on at this time. Therefore, the input end of the gate line 1 is connected with the pixel common electrode line 4 in the row next to the gate line 1 via the first TFT 11 , and is further connected with the output end of the gate line 1 via the fourth TFT 14 , so that another path is formed. These two paths have the same potential and transmit the gate signal simultaneously, which in effect reduces the resistance of the signal passage. When a high voltage signal (Vgh) is applied to the nth row, the remaining rows are controlled by a low voltage signal (Vgl), so that the nth row second TFT 12 is in operation, and the nth row third TFT 13 at the rightmost side of the panel is also in operation. At the same time, the (n+1)th row first TFT 11 , as well as the (n+1)th row fourth TFT 14 at the rightmost side of the panel, is turned off. Therefore, the two peripheral common electrode lines 3 on the two sides of the panel are connected with each other via the second TFT 12 , the third TFT 13 , and the pixel common electrode line 4 in the (n+1)th row. The nth row storage capacitor is still applied with the signal voltage of the peripheral common electrode lines 3 , and the nth row can be charged normally.
That is, when a row is applied with a high voltage signal, there are two paths for the row which transmit the gate signal, i.e., the original gate line 1 and the path which is formed by connecting the input end and output end of the gate line 1 to the pixel common electrode line 4 in the row next to the gate line 1 via the first TFT 11 and the fourth TFT 14 , respectively. When a row is applied with a low voltage signal, the first TFT 11 and the fourth TFT 14 in the row are turned off, and the peripheral common electrode lines 3 are connected by the second TFT 12 , the third TFT 13 , and the pixel common electrode line 4 in the row, as the common electrode of the storage capacitors.
The structure and design method described above can not only effectively reduce the resistance of the gate line and the delay of signal, but also make a compromise between the aperture ratio and the increase of the line width which is necessary to reduce the signal delay on the gate line.
It should be appreciated that the embodiments described above are intended to illustrate but not limit the present invention. Although the present invention has been described in detail herein with reference to the preferred embodiments, it should be understood by those skilled in the art that the present invention can be modified and some of the technical features can be equivalently substituted without departing from the spirit and scope of the present invention.
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In a thin film transistor liquid crystal display (TFT-LCD), a connection is formed between the gate line and the common electrode line with TFTs. During scanning in one frame, a high voltage signal is applied to the pixels in a next row before the next row is turned on, i.e., a black image is inserted in the normal white mode. When the pixels in one row are in operation and the pixels in the next row are not turned on, a black image data is inserted into the next row. A high voltage is applied before the pixels in a row of the TFT-LCD are turned on, so that a black image is inserted and tailing of motion picture can be alleviated.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wellbore completion. More particularly, the invention relates to effectively increasing the carrying capacity of the circulating fluid without damaging wellbore formations. More particularly still, the invention relates to removing cuttings in a wellbore during a drilling operation.
2. Description of the Related Art
In the drilling of oil and gas wells, a wellbore is formed using a drill bit that is urged downwardly at a lower end of a drill string. After drilling a predetermined depth, the drill string and bit are removed, and the wellbore is lined with a string of casing with a specific diameter. An annular area is thus defined between the outside of the casing and the earth formation. This annular area is filled with cement to permanently set the casing in the wellbore and to facilitate the isolation of production zones and fluids at different depths within the wellbore.
It is common to employ more than one string of casing in a wellbore. In this respect, a first string of casing is set in the wellbore when the well is drilled to a first designated depth. The well is then drilled to a second designated depth and thereafter lined with a string of casing with a smaller diameter than the first string of casing. This process is repeated until the desired well depth is obtained, each additional string of casing resulting in a smaller diameter than the one above it. The reduction in the diameter reduces the cross-sectional area in which circulating fluid may travel.
Typically, fluid is circulated throughout the wellbore during the drilling operation to cool a rotating bit and remove wellbore cuttings. The fluid is generally pumped from the surface of the wellbore through the drill string to the rotating bit. Thereafter, the fluid is circulated through an annulus formed between the drill string and the string of casing and subsequently returned to the surface to be disposed of or reused. As the fluid travels up the wellbore, the cross-sectional area of the fluid path increases as each larger diameter string of casing is encountered. For example, the fluid initially travels up an annulus formed between the drill string and the newly formed wellbore at a high annular velocity due to small annular clearance. However, as the fluid travels the portion of the wellbore that was previously lined with casing, the enlarged cross-sectional area defined by the larger diameter casing results in a larger annular clearance between the drill string and the cased wellbore, thereby reducing the annular velocity of the fluid. This reduction in annular velocity decreases the overall carrying capacity of the fluid, resulting in the drill cuttings dropping out of the fluid flow and settling somewhere in the wellbore. This settling of the drill cuttings and debris can cause a number of difficulties to subsequent downhole operations. For example, it is well known that the setting of tools against a casing wall is hampered by the presence of debris on the wall.
Several methods have been developed to prevent the settling of the drill cuttings and debris by overcoming the deficiency of the carrying capacity of the circulating fluid. One such method is used in a deepwater application where the increased diameter of the drilling riser results in a lower annular velocity in the riser system. Generally, fluid from the surface of the floating vessel is injected into a lower portion of the riser system through a flow line disposed on the outside of the riser pipe. This method is often referred to as “charging the riser”. This method effectively increases the annular velocity and carrying capacity of the circulating fluid to assist in wellbore cleaning. However, this method is not practical for downhole operations.
Another method to prevent the settling of the drill cuttings and debris is by simply increasing the flow rate of the circulating fluid over the entire wellbore interval to compensate for the lower annular velocity in the larger annular areas. This method increases the annular velocity in the larger annular areas, thereby minimizing the amount of settling of the drill cuttings and debris. However, the higher annular velocity also increases the potential of wellbore erosion and increases the equivalent circulating density, which deals with the friction forces brought about by the circulation of the fluid. Neither effect is desirable, but this method is often used by operators to compensate for the poor downhole cleaning due to lower annular velocity of the circulating fluid.
Potential problems associated with flow rate and the velocity of return fluid while drilling are increased when the wellbore is formed by a technique known as “drilling with casing”. Drilling with casing is a method where a drill bit is attached to the same string of tubulars that will line the wellbore. In other words, rather than run a drill bit on smaller diameter drill string, the bit is run at the end of larger diameter tubing or casing that will remain in the wellbore and be cemented therein. The bit is typically removed in sections or destroyed by drilling the next section of the wellbore. The advantages of drilling with casing are obvious. Because the same string of tubulars transports the bit as lines the wellbore, no separate trip into the wellbore is necessary between the forming of the wellbore and the lining of the wellbore.
Drilling with casing is especially useful in certain situations where an operator wants to drill and line a wellbore as quickly as possible to minimize the time the wellbore remains unlined and subject to collapse or to the effects of pressure anomalies. For example, when forming a subsea wellbore, the initial length of wellbore extending from the ocean floor is much more subject to cave in or collapse due to soft formations as the subsequent sections of wellbore. Sections of a wellbore that intersect areas of high pressure can lead to damage of the wellbore between the time the wellbore is formed and when it is lined. An area of exceptionally low pressure will drain expensive circulating fluid from the wellbore between the time it is intersected and when the wellbore is lined.
In each of these instances, the problems can be eliminated or their effects reduced by drilling with casing. However, drilling with casing results in a smaller annular clearance between the outer diameter of the casing and the inner diameter of the newly formed wellbore. This small annular clearance causes the circulating fluid to travel through the annular area at a high annular velocity, resulting in a higher potential of wellbore erosion compared to a conventional drilling operation.
A need therefore exists for an apparatus and a method for preventing settling of drill cuttings and other debris in the wellbore during a drilling operation. There is a further need for an apparatus and a method that will effectively increase the carrying capacity of the circulating fluid without damaging wellbore formations. There is yet a further need for a cost-effective method for cleaning out a wellbore while drilling with casing.
SUMMARY OF THE INVENTION
The present invention generally relates to a method and an apparatus for drilling with casing. In one aspect, a method of drilling a wellbore with casing is provided, including placing a string of casing with a drill bit at the lower end thereof into a previously formed wellbore and urging the string of casing axially downward to form a new section of wellbore. The method further includes pumping fluid through the string of casing into an annulus formed between the casing string and the new section of wellbore. The method also includes diverting a portion of the fluid into an upper annulus in the previously formed wellbore.
In another aspect, a method of drilling with casing to form a wellbore is provided. The method includes placing a casing string with a drill bit at the lower end thereof into a previously formed wellbore and urging the casing string axially downward to form a new section of wellbore. The method further includes pumping fluid through the casing string into an annulus formed between the casing string and the new section of wellbore. Additionally, the method includes diverting a portion of the fluid into an upper annulus in the previously formed wellbore from a flow path in a run-in string of tubulars disposed above the casing string.
In yet another aspect, an apparatus for forming a wellbore is provided. The apparatus comprises a casing string with a drill bit disposed at an end thereof and a fluid bypass formed at least partially within the casing string for diverting a portion of fluid from a first to a second location within the casing string as the wellbore is formed.
In another aspect, a method of casing a wellbore while drilling the wellbore is provided, including flowing a fluid through a drilling apparatus. The method also includes operating the drilling apparatus to drill the wellbore, the drilling apparatus comprising a drill bit, a wellbore casing, and a fluid bypass. The method further includes diverting a portion of the flowing fluid with the fluid bypass and placing at least a portion of the wellbore casing in the drilled wellbore.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
FIG. 1 is a cross-sectional view illustrating a flow apparatus disposed at the lower end of the run-in string.
FIG. 2A is a cross-sectional view illustrating an auxiliary flow tube partially formed in a casing string.
FIG. 2B is a cross-sectional view illustrating a main flow tube formed in the casing string.
FIG. 3 is a cross-sectional view illustrating the flow apparatus and auxiliary flow tube in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention relates to apparatus and methods for effectively increasing the carrying capacity of the circulating fluid without damaging wellbore formations. The invention will be described in relation to a number of embodiments and is not limited to any one embodiment shown or described.
FIG. 1 is a section view of a wellbore 100 . For clarity, the wellbore 100 is divided into an upper wellbore 100 A and a lower wellbore 100 B. The upper wellbore 100 A is lined with casing 110 and an annular area between the casing 110 and the upper wellbore 100 A is filled with cement 115 to strengthen and isolate the upper wellbore 100 A from the surrounding earth. At a lower end of the upper wellbore 100 A, the casing 110 terminates and the subsequent lower wellbore 100 B is formed. Coaxially disposed in the wellbore 100 is a work string 120 made up of tubulars with a running tool 130 disposed at a lower end thereof. Generally, the running tool 130 is used in the placement or setting of downhole equipment and may be retrieved after the operation or setting process. The running tool 130 in this invention is used to connect the work string 120 to a casing string 150 and subsequently release the casing string 150 after the lower wellbore 100 B is formed and the casing string 150 is secured.
As illustrated, a drill bit 125 is disposed at the lower end of the casing string 150 . Generally, the lower wellbore 100 B is formed as the drill bit 125 is rotated and urged axially downward. The drill bit 125 may be rotated by a mud motor (not shown) located in the casing string 150 proximate the drill bit 125 or by rotating the casing string 150 . In either case, the drill bit 125 is attached to the casing string 150 that will subsequently remain downhole to line the lower wellbore 100 B, therefore there is no opportunity to retrieve the drill bit 125 in the conventional manner. In this respect, drill bits made of drillable material, two-piece drill bits or bits integrally formed at the end of casing string are typically used.
Circulating fluid or “mud” is circulated down the work string 120 , as illustrated with arrow 145 , through the casing string 150 and exits the drill bit 125 . The fluid typically provides lubrication for the drill bit 125 as the lower wellbore 100 B is formed. Thereafter, the fluid combines with other wellbore fluid to transport cuttings and other wellbore debris out of the wellbore 100 . As illustrated with arrow 170 , the fluid initially travels upward through a smaller annular area 175 formed between the outer diameter of the casing string 150 and the lower wellbore 100 B. Generally, the velocity of the fluid is inversely proportional to the annular area defining the fluid path. In other words, if the fluid path has a large annular area then the velocity of the fluid is low. Conversely, if the fluid path has a small annular area then the velocity of the fluid is high. Therefore, the fluid traveling through the smaller annular area 175 has a high annular velocity.
Subsequently, the fluid travels up a larger annular area 140 formed between the work string 120 and the inside diameter of the casing 110 in the upper wellbore 100 A as illustrated by arrow 165 . As the fluid transitions from the smaller annular area 175 to the larger annular area 140 the annular velocity of the fluid decreases. Similarly, as the annular velocity decreases, so does the carrying capacity of the fluid resulting in the potential settling of drill cuttings and wellbore debris on or around the upper end of the casing string 150 . To increase the annular velocity, a flow apparatus 200 is used to inject fluid into the larger annular area 140 .
Disposed on the work string 120 and shown schematically in FIG. 1 is the flow apparatus 200 . Although FIG. 1 shows one flow apparatus 200 attached to the work string 120 , any number of flow apparatus may be attached to the work string 120 or the casing string 150 in accordance with the present invention. The purpose of the flow apparatus 200 is to divert a portion of the circulating fluid into the larger annular area 140 to increase the annular velocity of the fluid traveling up the wellbore 100 . It is to be understood, however, that the flow apparatus 200 may be disposed on the work string 120 at any location, such as adjacent the casing string 150 as shown on FIG. 1 or further up the work string 120 . Furthermore, the flow apparatus 200 may be disposed in the casing string 150 or below the casing string 150 providing the lower wellbore 100 B would not be eroded or over pressurized by the circulating fluid.
One or more ports 215 in the flow apparatus 200 may be modified to control the percentage of flow that passes to drill bit 125 and the percentage of flow that is diverted to the larger annular area 140 . The ports 215 may also be oriented in an upward direction to direct the fluid flow up the larger annular area 140 , thereby encouraging the drill cuttings and debris out of the wellbore 100 . Furthermore, the ports 215 may be systematically opened and closed as required to modify the circulation system or to allow operation of a pressure controlled downhole device.
The flow apparatus 200 is arranged to divert a predetermined amount of circulating fluid from the flow path down the work string 120 . The diverted flow, as illustrated by arrow 160 , is subsequently combined with the fluid traveling upward through the larger annular area 140 . In this manner, the annular velocity of fluid in the larger annular area 140 is increased which directly increases the carrying capacity of the fluid, thereby allowing the cuttings and debris to be effectively removed from the wellbore 100 . At the same time, the annular velocity of the fluid traveling up the smaller annular area 175 is lowered as the amount of fluid exiting the drill bit 125 is reduced. In this respect, the annular velocity of the fluid traveling down the work string 120 is used to effectively transport drill cutting and other debris up the larger annular area 140 while minimizing erosion in the lower wellbore 100 B by the fluid traveling up the annular area 175 .
FIG. 2A is a cross-sectional view illustrating an auxiliary flow tube 205 partially formed in the casing string 150 . As illustrated with arrow 145 , circulating fluid is circulated down the work string 120 through the casing string 150 and exits the drill bit 125 to provide lubrication for the drill bit 125 as the lower wellbore 100 B is formed. Thereafter, the fluid combines with other wellbore fluid to transport cuttings and other wellbore debris out of the wellbore 100 . As illustrated with arrow 170 , the fluid initially travels at a high annular velocity upward through a portion of the smaller annular area 175 formed between the outer diameter of the casing string 150 and the lower wellbore 100 B. However, at a predetermined distance, a portion of the fluid, as illustrated by arrow 210 , is redirected to the auxiliary flow tube 205 disposed in the casing string 150 . Furthermore, the auxiliary flow tube 205 may be systematically opened and closed as required to modify the circulation system or to allow operation of a pressure controlled downhole device.
The auxiliary flow tube 205 is constructed and arranged to remove and redirect a predetermined amount of high annular velocity fluid traveling up the smaller annular area 175 . In other words, the auxiliary flow tube 205 increases the annular velocity of the fluid traveling up the larger annular area 140 by diverting a portion of high annular velocity fluid in the smaller annular area 175 to the larger annular area 140 . Although FIG. 2A shows one auxiliary flow tube 205 attached to the casing string 150 , any number of auxiliary flow tubes may be attached to the casing string 150 in accordance with the present invention. Additionally, the auxiliary flow tube 205 may be disposed on the casing string 150 at any location, such as adjacent the drill bit 125 as shown on FIG. 2A or further up the casing string 150 , so long as the high annular velocity fluid in the smaller annular area 175 is transported to the larger annular area 140 . In this respect, the annular velocity of fluid in the larger annular area 140 is increased which directly increases the carrying capacity of the fluid allowing the cuttings and debris to be effectively removed from the wellbore 100 . At the same time, the annular velocity of the fluid traveling up the smaller annular area 175 is reduced, thereby minimizing erosion or pressure damage in the lower wellbore 100 B by the fluid traveling up the annular area 175 .
FIG. 2B is a cross-sectional view illustrating a main flow tube 220 formed in the casing string 150 . As illustrated with arrow 145 , circulating fluid is circulated down the work string 120 through the casing string 150 and exits the drill bit 125 to provide lubrication as the lower wellbore 100 B is formed. Thereafter, the fluid combines with other wellbore fluid to transport cuttings and other wellbore debris out of the wellbore 100 . Subsequently, as illustrated with arrow 170 , a first portion of the fluid at a high annular velocity travels upward through a portion of the smaller annular area 175 formed between the outer diameter of the casing string 150 and the lower wellbore 100 B. A second portion of fluid, as illustrated by arrow 210 , travels through the main flow tube 220 to the larger annular area 140 . In the same manner as discussed in a previous paragraph, the annular velocity of fluid in the larger annular area 140 is increased and the annular velocity of the fluid in the smaller annular area 175 is reduced, thereby minimizing erosion or pressure damage in the lower wellbore 100 B by the fluid traveling up the annular area 175 .
FIG. 3 is a cross-sectional view illustrating the flow apparatus 200 and auxiliary flow tube 205 in accordance with the present invention. In the embodiment shown, the flow apparatus 200 is disposed on the work string 120 and the auxiliary flow tube 205 is disposed on the casing string 150 . It is to be understood, however, that the flow apparatus 200 may be disposed on the work string 120 at any location, such as adjacent the casing string 150 as shown on FIG. 3 or further up the work string 120 . Furthermore, the flow apparatus 200 may be disposed in the casing string 150 or below the casing string 150 providing the lower wellbore 100 B would not be eroded or over pressurized by the fluid exiting the flow control apparatus 200 . In the same manner, the auxiliary flow tube 205 may be positioned at any location on the casing string 150 , so long as the high annular velocity fluid in the smaller annular area 175 is transported to the larger annular area 140 . Additionally, it is within the scope of this invention to employ a number of flow apparatus or auxiliary flow tubes.
Similar to the other embodiments, fluid is circulated down the work string 120 through the casing string 150 to lubricate and cool the drill bit 125 as the lower wellbore 100 B is formed. Thereafter, the fluid combines with other wellbore fluid to transport cuttings and other wellbore debris out of the wellbore 100 . However, in the embodiment illustrated in FIG. 3 , a portion of fluid pumped through the work string 120 may be diverted through the flow apparatus 200 into the larger annular area 140 at a predetermined point above the casing string 150 . At the same time, a portion of high velocity fluid traveling up the smaller annular area 175 may be communicated through the auxiliary flow tube 205 into the larger annular area 140 at a predetermined point below the upper end of the casing string 150 .
The operator may selectively open and close the flow apparatus 200 or the auxiliary flow tube 205 individually or collectively to modify the circulation system. For example, an operator may completely open the flow apparatus 200 and partially close the auxiliary flow tube 205 , thereby injecting circulating fluid in an upper portion of the larger annular area 140 while maintaining a high annular velocity fluid traveling up the smaller annular area 175 . In the same fashion, the operator may partially close the flow apparatus 200 and completely open the auxiliary flow tube 205 , thereby injecting high velocity fluid to a lower portion of the larger annular area 140 while allowing minimal circulating fluid into the upper portion of the larger annular area 140 . There are numerous combinations of selectively opening and closing the flow apparatus 200 or the auxiliary flow tube 205 to achieve the desired modification to the circulation system. Additionally, the flow apparatus 200 and the auxiliary flow tube 205 may be hydraulically opened or closed by control lines (not shown) or by other methods well known in the art.
In operation, a work string, a running tool and a casing string with a drill bit disposed at a lower end thereof are inserted into a wellhead and coaxially disposed in an upper wellbore. Subsequently, the casing string and the drill bit are rotated and urged axially downward to form the lower wellbore. At the same time, circulating fluid or “mud” is circulated down the work string through the casing string and exits the drill bit. The fluid typically provides lubrication for the rotating drill bit as the lower wellbore is formed. Thereafter, the fluid combines with other wellbore fluid to transport cuttings and other wellbore debris out of the wellbore. The fluid initially travels upward through a smaller annular area formed between the outer diameter of the casing string and the lower wellbore. Subsequently, the fluid travels up a larger annular area formed between the work string and the inside diameter of the casing lining the upper wellbore. As the fluid transitions from the smaller annular area to the larger annular area the annular velocity of the fluid decreases. Similarly, as the annular velocity decreases, so does the carrying capacity of the fluid resulting in the potential settling of drill cuttings and wellbore debris on or around the upper end of the casing string 150 .
A flow apparatus and an auxiliary flow tube are used to increase the annular velocity of the fluid traveling up the larger annular area by injecting high velocity fluid directly into the larger annular area. Generally, the flow apparatus is disposed on the work string to redirect circulating fluid flowing through the work string into an upper portion of the larger annular area. At the same time, the auxiliary flow tube is disposed on the casing string to redirect high velocity fluid traveling up the smaller annular area in a lower portion of the larger annular area. Both the flow apparatus and the auxiliary flow tube may be may selectively opened and closed individually or collectively to modify the circulation system. In this respect, if fluid is primarily required in the upper portion of the larger annular area then the flow apparatus may be completely opened and the auxiliary flow tube is closed. On the other hand, if fluid is primarily required in the lower portion of the larger annular area then the flow apparatus is closed and the auxiliary flow tube is opened. In this manner, the circulation system may be modified to increase the carrying capacity of the circulating fluid without damaging the wellbore formations.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
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The present invention generally relates to a method and an apparatus for drilling with casing. In one aspect, a method of drilling a wellbore with casing is provided, including placing a string of casing with a drill bit at the lower end thereof into a previously formed wellbore and urging the string of casing axially downward to form a new section of wellbore. The method further includes pumping fluid through the string of casing into an annulus formed between the casing string and the new section of wellbore. The method also includes diverting a portion of the fluid into an upper annulus in the previously formed wellbore. In another aspect, a method of drilling with casing to form a wellbore is provided. In yet another aspect, an apparatus for forming a wellbore is provided. In still another aspect, a method of casing a wellbore while drilling the wellbore is provided.
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TECHNICAL FIELD
[0001] The present disclosure pertains to the field of energy and chemical industry. It relates to, for example, a method for preparing hydrogen-rich gas through steam gasification of solid organic raw materials and their mixture, by using circulated solid heat carrier as heating medium, catalyst, and filter material for filtering and removing dust simultaneously.
BACKGROUND
[0002] It is an ideal model to prepare hydrogen-rich gas through steam gasification of solid organics. In order to achieve this, at least two problems need to be solved: providing heat required by steam gasification, and eliminating or decreasing tar in product gas.
[0003] Chinese Patent for Invention No. ZL200610113063.3 appears to disclose a decoupling fluidized bed gasification method and device. There, a fluidized bed reactor is divided into two interconnected rooms, in which one room is mainly used for drying and pyrolysis of solid fuel, and the other is used for semicoke-gasification and modification of tar and hydrocarbon. Heat required by pyrolysis and gasification is provided via combustion reaction of raw materials and semicoke with air or oxygen, which are fed into a same reaction space. The patent also provides a dual fluidized bed reaction device and method characterized by using the circulation of solid heat carrier, wherein the heat required by pyrolysis and gasification is partly provided by the combustion of unreacted semicoke in another fluidized bed reactor. Due to the employment of inner combustion for supplying heat, the gasification product gas would comprise inert nitrogen unless employing pure oxygen gasification agent. The limitation of fluidized gasification reactor also lies in: low reaction temperature; short stay time, which causes the conversion of tar and hydrocarbon insufficient; and high dustiness of the product gas. In addition, part of raw materials is directly combusted to supply heat, and thus the hydrogen is mainly converted into water, rather than efficiently enters into hydrogen-rich product gas, which is unreasonable from the view of element utilization.
[0004] Austria Vienna University of Technology purportedly developed a biomass gasification process with Fast Internally Circulating Fluidized Bed (FICFB) (reference: http://www.ficfb.at/). The structure of FICFB gasification reactor mainly comprises two reaction spaces: bubbling fluidized bed pyrolysis-gasification zone and fluidized bed rising-combustion zone, and the solid heat carrier circulated within these two zones. The solid heat carrier is heated through combustion of semicoke in the combustion zone and is circulated back to the pyrolysis zone and gasification zone to supply heat required by steam gasification and pyrolysis of biomass in the pyrolysis zone and the gasification zone. Then the solid heat carrier is re-fed into the combustion zone to start the next cycle. The gases of the two zones are separated with each other, therefore, hydrogen-rich gas without nitrogen can be produced. Pyrolysis and gasification of FICFB technology are performed at a same reaction space, which is hard to achieve independent control over pyrolysis and gasification, and has limitation to the adaptability of different raw materials. Both the stay time of biomass pyrolysis volatile matter in fluidized bed gasification reactor and the contacting time of the volatile matter with solid heat carrier are short, which leads to insufficient conversion of tar and high tar content of product gas. Therefore, the improvement of gasification efficiency is restrained. Where biomass, young brown coal, etc. are used as raw materials, the generated gaseous product may have a large amount of dust due to the pulverization of the raw materials during pyrolysis gasification process. If the dust cannot be efficiently removed in hot condition, the dust and the tar in gaseous product may form viscous mixture in the following condensation-purification process, which affects normal operation of system.
[0005] Chinese Patent for Invention No. ZL200710011214.9 appears to provide a method that enables independent control over pyrolysis of solid fuel raw materials, further decomposition and conversion of tar and hydrocarbon in the gaseous product generated by pyrolysis, and supplying heat to the reactions by combusting the semicoke from pyrolysis. The method is achieved through the circulation of solid heat carrier within three tandem reactors, which are moving bed pyrolysis reactor, moving bed gasification reactor, and riser and combustion reactor. The reactions respectively performed within the three reactors are: pyrolysis of solid fuel raw materials, steam gasification of gaseous product (including tar and low-carbon hydrocarbon) generated by pyrolysis, and combustion of semicoke and re-heating and rising of solid heat carrier. The limitation of the method is that, since the pyrolysis reactor and gasification reactor are tandem connected, the solid heat carrier from the riser and combustion reactor passes through the pyrolysis reactor and gasification reactor in turn, and then loops back to the riser and combustion reactor; therefore, the running conditions of the pyrolysis reactor and gasification reactor restrict each other. The temperature of the solid heat carrier fed into the pyrolysis reactor fully depends on the reaction degree within the gasification reactor, and the kinds and quantity of solid heat carrier fed into the pyrolysis reactor and gasification reactor cannot be respectively and independently controlled either. Therefore, it may be hard to achieve the goal that both pyrolysis reactor and gasification reactor are running at their respective optimal running conditions.
SUMMARY
[0006] To address the above issues, the present disclosure provides a method and device for preparing hydrogen-rich gas through steam gasification of solid organics. By using the circulation of solid heat carrier, independent and optimized control of rapid pyrolysis of solid organic raw materials and catalytic steam-involved decomposition and conversion of tar and hydrocarbon within gaseous product generated by pyrolysis can be achieved.
Example Embodiments of the Present Disclosure
[0007] Disclosed is a method for preparing hydrogen-rich gas through steam gasification of solid organic raw materials, with which rapid pyrolysis of solid organic raw materials and catalyzing steam gasification of gaseous product generated by pyrolysis can be respectively achieved by using the circulation of solid heat carrier. Pyrolysis reaction device and moving bed gasification reaction device may be disposed in parallel. The pyrolysis reaction device has one pyrolysis reactor or at least two parallel pyrolysis reactors, and the moving bed gasification reaction device has one moving bed gasification reactor or at least two parallel moving bed gasification reactors, wherein each pyrolysis reactor corresponds with at least one moving bed gasification reactor, or each moving bed gasification reactor corresponds with at least one pyrolysis reactor; wherein the gaseous product from each of the pyrolysis reactors is fed into the corresponding moving bed gasification reactor. The pyrolysis reactor can be a moving bed pyrolysis reactor or a fluidized bed pyrolysis reactor.
[0008] A part of solid heat carrier is used as heating medium for heating solid organic raw materials to be reacted. The other part is used as heating medium for gasification, and at the same time, can also be used as catalyst for gasification and particle filter material for capturing dust entrained in the gaseous product of pyrolysis. In an example embodiment, the part of solid heat carrier with smaller average particle size is used as heating medium for heating solid organic raw materials to allow rapid pyrolysis of the raw materials in order to get solid product and gaseous product. The other part of solid heat carrier with larger average particle size is used as heating medium and for capturing dust entrained in the gaseous product generated from pyrolysis, and at the same time, is used as catalyst to enable the gasification between the gaseous product generated from pyrolysis and steam so as to decompose and convert tar and low-carbon hydrocarbon into hydrogen-rich gas. The two parts of solid heat carrier with low temperature, whose temperatures have been reduced due to the participation of pyrolysis and gasification process, join together to be heated and risen. The solid heat carrier with high temperature which has been heated is subjected to dust removal and particle gradation and is divided into two parts, after that, the two parts of high temperature solid heat carrier respectively having smaller and larger average particle size are respectively used for pyrolysis and gasification again to form a cycle.
[0009] Specifically, the pyrolysis operation includes: pyrolysis of solid organic raw materials is performed in pyrolysis reaction device. The solid organic raw materials is rapidly mixed with the high temperature solid heat carrier with smaller average particle size in the mixing section of pyrolysis reaction device, and is rapidly transferred to the reacting section of pyrolysis reaction device. During this process, the solid organic raw materials are rapidly heated to pyrolysis temperature, i.e., 400° C.-800° C. Decomposition reaction of the solid organic raw materials which have been heated to pyrolysis temperature occurs in the reacting section of pyrolysis reaction device to generate gaseous pyrolysis product (including tar steam and low-carbon hydrocarbon) and solid pyrolysis product, wherein the solid pyrolysis product has carbon residue. In addition, some components of the gaseous pyrolysis product further react, which is so-called secondary reaction, to generate carbon deposit attached on the particle of solid heat carrier. The mixture of solid pyrolysis product and low temperature solid heat carrier leaves pyrolysis reaction device through quantitative delivery valve under the effect of gravity, and is fed into riser and combustion reactor. The gaseous product generated from pyrolysis together with the steam fed into pyrolysis device is drawn out from pyrolysis reaction device and fed into moving bed gasification reaction device.
[0010] Example functions of pyrolysis operation are that: on the one hand, the volatilizable organic matter in solid organic raw materials can be fully converted into gaseous product which is then converted into hydrogen-rich gas through the steam gasification of the gaseous product during gasification operation; on the other hand, pyrolysis of solid organic raw materials generates moderate amount of carbon deposit and solid product with carbon residue.
[0011] In an example embodiment, the solid organic raw materials may be selected from biomass, polymeric solid waste, coal, petroleum coke, or combinations thereof. The biomass means herbage and woody plants comprised of cellulose, hemicellulose and lignin, for example, agricultural waste (e.g. straw, bagassa and rice hull), forestry waste (e.g. bark, core shell and wood chips) or energy crop (e.g. miscanthus and pennisetum hydridum ), etc. In an example embodiment, the solid organics used as single raw material or used for mixed raw materials should have volatile matter in relatively high amount, e.g., between 20-70% (present in dry-ash-free basis mass fraction). The moisture upper limit of the raw materials should be appropriate for ensuring the raw materials to be smoothly transported into the mixing section of pyrolysis reaction device. The moisture of raw materials enters into moving bed gasification reaction device together with the gaseous product generated from pyrolysis, and participates in the catalyzing steam gasification of the gaseous product generated by pyrolysis. Therefore, moderate amount of moisture contained in the raw materials can reduce additional water amount.
[0012] In the pyrolysis operation, proper heating rate of the raw material and pyrolysis temperature are also required. These mainly depend on the composition and the particle size of raw materials, the particle size and temperature of solid heat carrier, and the mixing rate and ratio of solid heat carrier to raw materials. Under the condition that the composition of solid organic raw materials and the particle size and temperature of solid heat carrier are given, the temperature of pyrolysis reaction device can be adjusted through controlling the mixing ratio of solid heat carrier to raw materials, as such, the degree of pyrolysis of solid organic raw materials can be controlled. While pyrolysis reaction device runs in moving bed mode, in unit time, the mass ratio of the solid heat carrier fed into the pyrolysis reaction device to the solid organic raw material should be 2-7:1. According to the present disclosure, depending on practical situation, the specific ratio can be specifically chosen as 2:1, 3:1, 4:1, 5:1, 6:1 or 7:1, e.g., as 3-5:1. The temperature of pyrolysis reaction device should be controlled within the range from 400 to 800° C., e.g., from 500 to 700° C. The higher temperature of solid heat carrier is, the larger mass ratio of solid heat carrier to the solid organic raw material that fed into pyrolysis reaction device can be achieved. While pyrolysis reaction device runs in fluidized bed mode, in order to ensure that the solid organic raw materials can achieve required degree of pyrolysis, the mass ratio of solid heat carrier to solid organic raw materials should be increased, and the ratio can be as high as 40 or more. The smaller particle size of solid organic raw materials is advantageous for rapidly heating and decomposing. The proper upper limit of particle size of the solid organic raw materials of the invented method depends on whether the solid product of pyrolysis can be smoothly raised in riser and combustion reactor, and should be typically controlled below 8 mm. According to the specific experiment and analysis of the inventor of the present Application, based on practical situation, the particle size can be specifically chosen as 2 mm, 6 mm or 7.5 mm, and for example the particle size should be controlled below 3 mm.
[0013] Steam, which is one of the gasification raw materials, is fed from the lower portion of the solid material layer in pyrolysis reaction device. The benefits are: steam carrying gaseous pyrolysis product of solid organic raw materials quickly leaves pyrolysis reactor, which promotes the pyrolysis reaction and reduces the secondary reaction of gaseous product produced by pyrolysis so as to reduce the possibility of generating carbon deposit and carbon black. While pyrolysis reactor runs in fluidized bed mode, steam is used as fluidify medium and gaseous heat carrier at the same time. In order to ensure that pyrolysis reactor may get the required temperature, the temperature of overheated steam fed into pyrolysis reactor should be high enough, which is typically controlled above 300° C.; at the same time, the mixing ratio of solid heat carrier to solid organic raw materials fed into pyrolysis reactor should be properly increased, and small amount of oxygen can also be fed into pyrolysis reactor at the time of feeding steam if necessary.
[0014] The gasification operation includes: in moving bed gasification reaction device, through using the heat and the reaction surface provided by high temperature solid heat carrier, the tar and low-carbon hydrocarbon in gaseous product generated from pyrolysis in pyrolysis reaction device undergo further cracking reaction, and react with steam to generate hydrogen-rich gaseous product; at the same time, carbon deposit is normally formed on the surface of solid heat carrier. Hydrogen-rich gas product is collected through separating unreacted water and residual tar from the gaseous product by condensation-cooling device. While solid heat carrier having catalyst activity is employed, by the catalysis of the solid heat carrier, the cracking of tar and low-carbon hydrocarbon in gaseous pyrolysis product and the reaction with steam can be enhanced at a relatively low temperature. While gaseous product generated from pyrolysis flows through moving bed gasification reaction device, the dust entrained in the gaseous product is captured by solid heat carrier particle bed layer. The solid heat carrier with reduced temperature leaves gasification reaction device, and sent to riser and combustion reactor together with the captured dust.
[0015] The main function of gasification operation is to react tar and low-carbon hydrocarbon of gaseous product generated from pyrolysis with steam, which is to decompose and convert them into hydrogen-rich gas. The reaction is a strongly endothermic reaction, therefore basic conditions for ensuring the reaction taking place smoothly are high temperature, catalyst, and the efficient distribution and stay of reactant in catalyst bed layer. The temperature of moving bed gasification reaction device is normally controlled at 800˜950° C. In specific condition, for example, while the target product is gaseous product with high hydrogen concentration and calcium oxide is employed as carbon dioxide adsorbent, the lower limit of the temperature of moving bed gasification reaction device can be low to 700° C. In the circumstance that the running condition of pyrolysis reaction device is given, the temperature of moving bed gasification reaction device can be adjusted by means of temperature and circulation rate of solid heat carrier fed into gasification reaction device.
[0016] The quantity of solid heat carrier fed into moving bed gasification reaction device can be determined according to the influence of the dust removing efficiency and carbon deposit situation of solid heat carrier on the catalyst efficiency of solid heat carrier which is used as catalyst. On the premise of ensuring reaction system energy balance, increasing circulation rate of solid heat carrier in gasification reaction device is advantageous for shortening the stay time, reducing carbon deposit on the solid heat carrier which is as catalyst so as to avoid permanent inactivation of catalyst due to excessive carbon deposit. Controlling proper circulation rate of solid heat carrier can avoid overlarge resistance of bed layer due to the capture of dust, while ensuring the dust removing efficiency of moving particle layer. In unit time, the mass ratio of solid heat carrier fed into moving bed gasification reaction device to those fed into pyrolysis reaction device should be controlled at 0.1-5. According to the present Application, based on practical situation, the ratio may be specifically chosen as 0.5, 1, 3 and 4.5, all of which can be achieved by the present disclosure.
[0017] In moving bed gasification reactor, the mixture of gaseous product generated from pyrolysis in the pyrolysis reaction device and the steam contacts with solid heat carrier particle moving layer in a contact mode. The contact mode may be selected from a group consisting of parallel current, counter current, radically cross current, or combinations of the above gas-solid contact and flow modes. When nickel-based or iron-based catalyst is used as the solid heat carrier, the gas-solid contact mode of counter current or radically cross current is advantageous for the self-reduction of catalyst (i.e. in reducing atmosphere, metallic oxide on the carrier is reduced to pure metal having catalyst activity) and improving the stay time for efficient reaction. In addition, radically-cross-current moving solid heat carrier particle bed layer also has many advantages: large contacting area of gas-solid phase in unit reactor volume, low flow rate at which gas passes through moving particle bed layer, decreased resistance and so on. Therefore, radically-cross-current moving solid heat carrier particle bed layer is the preferred for the method of the present disclosure. Employment of radically-cross-current moving bed gasification reactor can also efficiently capture the dust entrained in gaseous product of pyrolysis.
[0018] The heating and rising operations include: in the bottom of riser and combustion reactor, the mixture of the solid product generated from pyrolysis in pyrolysis reaction device and solid heat carrier attached with carbon deposit, together with the solid heat carrier attached with carbon deposit from moving bed gasification reaction device, is fluidized and raised by hot air. During the process of rising, the carbon residue of solid product and the carbon deposit on the surface of solid heat carrier are burnt to generate heat and flue gas. Solid heat carrier is heated by the generated heat to give a high temperature solid heat carrier. High temperature solid heat carrier and the generated dust-bearing hot flue gas enter into solid heat carrier grading-dedusting device.
[0019] The main function of riser and combustion reactor is to regenerate the solid heat carrier, which is used as heating medium, catalyst and moving-particle filter material, while solid heat carrier is raised by hot airflow. The mixture of low temperature solid heat carrier and solid product generated from pyrolysis which leaves pyrolysis reaction device is fed into the bottom of riser and combustion reactor; at the same time, low temperature solid heat carrier, which already captures dust and leaves moving bed gasification reactor, is also quantitatively transported here.
[0020] Congregated low temperature solid heat carrier together with solid product generated from pyrolysis is rapidly fluidized and raised by hot air. During the process of rising, the carbon residue of solid product and the carbon deposit on the surface of solid heat carrier are burnt, and solid heat carrier is heated by the generated heat. In order to enable the carbon residue of solid product (i.e. the combustibles in solid pyrolysis product) and carbon deposit on solid heat carrier to be burnt in riser and combustion reactor, the temperature of the air fed into the inlet of riser and combustion reactor should be higher than the flammable point of the carbon residue and carbon deposit in solid product; normally, the temperature is higher than 400° C. In order to ensure the regeneration of solid heat carrier that is used as heating medium to meet the heat requirement of pyrolysis reaction device and gasification reaction device, when the solid heat carrier leaves riser and combustion reactor, its temperature should be high enough, which should normally reach 800˜1000° C., and the upper limit of the temperature should be lower than the melting temperature of the ash of solid product generated from pyrolysis. In order to ensure the regeneration of solid heat carrier which is used as catalyst, the carbon deposit on solid heat carrier has to be completely burnt. In order to achieve the objective, besides meeting the combustion conditions of riser and combustion reactor (such as temperature, oxygen concentration, stay time of solid heat carrier and so on), the quantity and type of carbon deposit attaching to solid heat carrier fed into riser and combustion reactor should also be controlled, for example, by controlling proper stay time of solid heat carrier in moving bed gasification reaction device. In the situation that the operation condition of riser and combustion reactor cannot meet the requirement for totally combusting the carbon deposit on solid heat carrier catalyst, a special carbon-burning regenerator should be disposed before pyrolysis reaction device and moving bed gasification reaction device, to make sure that the solid heat carrier catalyst has no carbon deposit attached when being circulated back to pyrolysis reaction device and moving bed gasification reaction device.
[0021] In the circumstance of fluidization and high temperature of riser and combustion reactor, solid heat carrier particle will be inevitably worn. Therefore, solid heat carrier particles with good high temperature mechanical strength should be employed, at the same time, solid heat carrier should be replenished in time through the replenishment solid heat carrier inlet disposed at riser and combustion reactor.
[0022] Auxiliary fuel may be added through the auxiliary fuel inlet, which is disposed at the bottom of riser and combustion reactor, to supplement heat through combustion thereof, if the solid product generated from pyrolysis of the solid organic raw materials has a low yield of carbon residue, such that the combustion of the carbon residue of the solid product in the riser and combustion reactor is not sufficient to provide desired heat of reaction system. Gas or liquid or solid fuel can be used as the auxiliary fuel. The auxiliary fuel fed from the bottom of riser and combustion reactor can also be used for igniting and starting operations of the reaction system
[0023] To solve the problem that the solid product generated from pyrolysis of the solid organic raw material has a low yield of carbon residue, such that the combustion of the carbon residue of the solid product in the riser and combustion reactor is not sufficient to provide desired heat of reaction system, another efficient way is using co-gasification, i.e. some solid product generated from pyrolysis with a high yield of carbon residue (such as petroleum coke) are added into the solid organic raw materials to be fed into pyrolysis reaction device, to give a mixed raw materials. The solid product generated from pyrolysis of the mixed raw materials would have a high enough yield of carbon residue, such that the combustion of this solid product is able to provide heat desired for the reaction system. As compared with directly combusting auxiliary fuel in riser and combustion reactor, the advantage of this method is the hydrogen-rich compositions of the raw materials can be transported to the product during the process of co-pyrolysis, rather than directly combusted.
[0024] The dust removing and size grading operations for the solid heat carrier include: high temperature solid heat carrier which has been heated in the riser and combustion reactor, together with hot flue gas, enters into solid heat carrier grading-dedusting device, in which the solid heat carrier, which is used as moving particle filter material, is regenerated via dust removal. Based on the difference of flow rate of solid heat carrier entraining dust fed into the solid heat carrier grading-dedusting device, by using the difference in density, inertia force or centrifugal force, or the combination of two or three of them between solid particles with different sizes, the solid heat carrier can be separated from dust-bearing hot flue gas, and divided into two parts with smaller or larger average particle size each. After leaving the solid heat carrier grading-dedusting device, the dust-bearing hot flue gas is emitted after being subjected to dust removing and heat recycling. As heat medium, the two parts of solid heat carrier with smaller and large average particle size each are fed into pyrolysis reaction device and gasification reaction device respectively for a new round of operation, so as to form said cycle. The grading of solid heat carrier particle can also be achieved by the method of mechanical sieving.
[0025] The role of solid heat carrier particle grading is: as heating medium in pyrolysis reaction device, small particle solid heat carrier has larger specific surface area, and is easier to achieve rapidly mixing and heating with solid organic raw materials in a smaller mixing ratio, such that the organic matter in solid organic raw materials can be fully converted into gaseous product, and further into hydrogen-rich gas through steam gasification. As heating medium, catalyst and moving particle filter material in moving bed gasification reaction device, solid heat carrier particle with larger average particle size is advantageous for reducing the resistance when gaseous product generated from pyrolysis flows through solid heat carrier moving particle layer, and is advantageous for the gas-solid heterogeneous catalytic gasification being performed smoothly, and at the same time, capturing the dust entrained in the gaseous product generated from pyrolysis.
[0026] It can be seen that, the method of the disclosure includes two parallel circulations of solid heat carrier:
[0027] I. The circulation of solid heat carrier used for heating solid organic raw material to achieve rapid pyrolysis: While being separated from dust-bearing hot flue gas in solid heat carrier grading-dedusting device, high temperature solid heat carrier from riser and combustion reactor is divided into two parts according to the difference of average particle size. As a heating medium, solid heat carrier with smaller average particle size is mixed with solid organic raw materials in pyrolysis reaction device such that the solid organic raw materials are heated to be pyrolyzed. Afterwards, low temperature solid heat carrier, whose temperature is decreased due to providing heat for heating solid organic raw materials, is mixed with the solid heat carrier from gasification reaction device; the mixture is heated to a high temperature by riser and combustion reactor and raised to be fed into the solid heat carrier grading-dedusting device, to start another circulation.
[0028] II. The circulation of solid heat carrier used as heating medium, catalyst and moving particle filter material simultaneously: While being separated from dust-bearing hot flue gas in solid heat carrier grading-dedusting device, the high temperature solid heat carrier from the riser and combustion reactor is divided into two parts according to the difference of average particle size. Solid heat carrier with larger average particle size enters into moving bed gasification reaction device, and heats the gaseous product from pyrolysis reaction device to allow pyrolysis and catalytic steam gasification occur. At the same time, the dust entrained in gaseous product from pyrolysis reaction device is captured by solid heat carrier particle layer. Afterwards, the solid heat carrier with decreased temperature and captured dust enters into riser and combustion reactor, and is mixed with the solid heat carrier and the solid product from pyrolysis reaction device to give a mixture, and the mixture is then heated and raised. During the process of being heated and raised, carbon deposit on the surface of solid heat carrier is burnt, through which the solid heat carrier used as catalyst is regenerated. Afterwards, high temperature solid heat carrier goes back to solid heat carrier grading-dedusting device to start another circulation.
[0029] In an example embodiment, hard-burned olivine exhibits relatively good high temperature abrasion resistance, and has catalyst activity for steam gasification of tar and low-carbon hydrocarbon. Therefore, hard-burned olivine is the basic solid heat carrier for the present disclosure. Proper solid heat carriers for the present disclosure also include silica sand, corundum sand, calcined magnesite, high-temperature ceramic materials, mullite, zircon sand, iron sand, solid generated from pyrolysis of raw materials (i.e. the solid product generated from pyrolysis of raw materials can also be circularly used as solid heat carrier), or combinations of two or more of them
[0030] In an example embodiment, the preferred embodiment of the solid heat carrier is a heat-resisting solid catalyst that has catalyst activity for steam-involved decomposition-conversion reaction of gaseous product generated from pyrolysis, which can be olive, or olivine-supported nickel-based catalyst, or olivine-supported iron-based catalyst, or nickel-based perovskite catalyst, or commercial nickel-based catalyst, or the combinations of them.
[0031] In an example embodiment, limestone or dolomite or calcite can be used together with the solid heat carrier to function as desulfurizer, carbon dioxide adsorbent and solid heat carrier. Not only is this advantageous for the steam-involved decomposition and conversion of tar and low-carbon hydrocarbon, but also advantageous for desulfurizing and improving the hydrogen content of gas product. Taking the case of limestone being added as an example, at the high temperature of riser and combustion reactor, limestone is decomposed to give calcium oxide. The calcium oxide, which is circulated back to pyrolysis reaction device, is not only used as heat carrier to provide the heat required by pyrolysis of solid organic, but also used as desulfurizer to react with the hydrogen sulfide generated from the process of pyrolysis, and bring the generated sulfur into the riser and combustion reactor, which may prevent the generated sulfur from entering into the moving bed gasification reaction device and further entering into gas product. The sulfur entering into moving bed gasification reaction device will make the nickel-based catalyst deactivated. The calcium oxide, which is circulated back to pyrolysis reaction device and moving bed gasification reaction device, can be used as carbon dioxide adsorbent to react with carbon dioxide entrained in gaseous pyrolysis product to generate calcium carbonate. This reaction can promote the water gas conversion reaction, thereby improving the hydrogen content of product gas. At the same time, the reaction is an exothermic reaction, which is thus advantageous for improving the heat balance of the reaction system. However, when being performed at atmospheric pressure and relatively low temperature, the reaction is efficient in thermodynamics. Therefore, the reaction mainly occurs in pyrolysis reaction device with relatively low temperature. In order to promote the reaction occurring in moving bed gasification reaction device, the temperature of moving bed gasification reaction device should be controlled at a relatively low temperature, for example, 700-750° C.
[0032] The upper limit of particle of the foregoing solid heat carrier is determined depending on whether it can be smoothly raised in riser and combustion reactor. Normally, the upper limit of particle of the foregoing solid heat carrier is controlled below 6 mm.
[0033] In an example embodiment, the operation pressure of each reactor is atmospheric pressure; the temperature of pyrolysis reaction device is 400˜800° C., the temperature of moving bed gasification reaction device is 700˜950° C., and the temperature of riser and combustion reactor is 800˜1100° C.
[0034] The present disclosure also provides a system for preparing hydrogen-rich gas through steam gasification of solid organic raw materials. The system may comprise the following parts: solid heat carrier grading-dedusting device 1 , pyrolysis reactor 2 , moving bed gasification reactor 3 , riser and combustion reactor 4 , condensation-cooling system 5 , and so on. For the circulations of solid heat carrier, pyrolysis reactor 2 and moving bed gasification reactor 3 are disposed in parallel. That is to say, after leaving solid heat carrier grading-dedusting device 1 , a part of the solid heat carrier enters into pyrolysis reactor 2 , and the other part enters into moving bed gasification reactor 3 .
[0035] In the present disclosure, a pyrolysis reactor may be a moving bed pyrolysis reactor or a fluidized bed pyrolysis reactor. One riser and combustion reactor can be used in correspondence with a combination of one pyrolysis reactor and one moving bed gasification reactor, which are disposed in parallel, and the gaseous product generated from pyrolysis reaction is fed into moving bed gasification reactor. Regarding the mismatching between riser and combustion reactor and the combination of pyrolysis reactor and moving bed gasification reactor, specifically, the production capacity of riser and combustion reactor is relatively high, while the single reactor volume and processing capacity of both pyrolysis reactor and moving bed gasification reactor are relatively low, the following ways can be employed in the rapid pyrolysis method of the present disclosure to improve the production capacity of single system: one riser and combustion reactor is used in combination with two or more parallel pyrolysis reactors (e.g., FIG. 3 shows two pyrolysis reactors 21 , 22 disposed in parallel), wherein the mixtures of steam and gaseous pyrolysis product entraining dust from all of the parallel pyrolysis reactors join together and are fed into a common moving bed gasification reactor. Or otherwise, one riser and combustion reactor is used in combination with a combination of two or more parallel pyrolysis reactors and two or more parallel moving bed gasification reactors, wherein each pyrolysis reactor corresponds to one or more moving bed gasification reactor, or each moving bed gasification reactor corresponds to one or more pyrolysis reactor, and the gaseous pyrolysis product generated from pyrolysis reactor is respectively fed into corresponding moving bed gasification reactor.
[0036] Solid heat carrier grading-dedusting device 1 has an inlet for feeding the mixture of solid heat carrier particle and flue gas entraining dust and an outlet for discharging dust-bearing flue gas at the upper portion, and a small particle solid heat carrier outlet and a large particle solid heat carrier outlet at the lower portion. The small and large particle solid heat carrier outlets respectively provide access to pyrolysis reactor 2 and moving bed gasification reactor 3 disposed under the solid heat carrier grading-dedusting device.
[0037] Moving bed pyrolysis reactor 2 includes two parts, which are built-in or pre-mixing section and reacting section. Solid organic raw materials and small particle solid heat carrier from solid heat carrier grading-dedusting device 1 respectively are fed into the mixing section of moving bed pyrolysis reactor, and then fed into the reacting section after being completely mixed. The moving bed pyrolysis reactor has an outlet at the bottom end, which is used for the feeding of the mixture of solid heat carrier and solid pyrolysis product into riser and combustion reactor 4 . The moving bed pyrolysis reactor has a gaseous product outlet at the upper portion which is connected with moving bed gasification reactor 3 to provide an access for feeding the mixture of gaseous pyrolysis product and steam into moving bed gasification reactor. A steam inlet is also disposed at the bottom of moving bed pyrolysis reactor. Solid material level detecting and controlling mechanism is disposed at moving bed pyrolysis reactor, to keep the solid material level of pyrolysis reacting section below the outlet for discharging gaseous product generated from pyrolysis.
[0038] The upper inlet of moving bed gasification reactor 3 is connected with the large particle solid heat carrier outlet of solid heat carrier grading-dedusting device 1 , and the lower outlet of the moving bed gasification reactor is connected with the bottom of riser and combustion reactor 4 . An inlet for feeding the mixture of gaseous pyrolysis product entraining dust and steam and an outlet for discharging gas product of steam gasification are disposed on moving bed gasification reactor, and are respectively connected with moving bed pyrolysis reactor 2 and condensation-cooling system 5 .
[0039] Riser and combustion reactor 4 , at the bottom, is equipped with a hot air inlet, an inlet for the mixture of solid heat carrier from pyrolysis reactor and solid product, and an inlet for solid heat carrier from moving bed gasification reactor which already captures dust. An additional inlet for replenishing solid heat carrier and auxiliary fuel is disposed at the bottom of riser and combustion reactor. The upper outlet of riser and combustion reactor is connected with solid heat carrier grading-dedusting device.
[0040] Special carbon-burning regenerator 6 and 7 can be respectively disposed between the solid heat carrier grading-dedusting device 1 and the moving bed pyrolysis reactor 2 , and between the solid heat carrier grading-dedusting device 1 and the moving bed gasification reactor 3 . Moving bed reactor or fluidized bed reactor can be employed as the carbon-burning regenerator.
[0041] With the aid of the material sealing effect caused by solid heat carrier in the pipelines which connect adjacent reactors, the atmosphere in moving bed pyrolysis reactor and moving bed gasification reactor, the atmosphere in solid heat carrier grading-dedusting device located above, and the atmosphere of riser and combustion reactor located beneath are shut off from each other, and have no leakage to each other. Therefore, hydrogen-rich gas product nearly without nitrogen can be achieved.
[0042] The operation pressure of each of the foregoing reactors is atmospheric pressure.
[0043] As compared with the prior art, various technical features and technical effects may be achieved by disclosed systems and methods for preparing hydrogen-rich gas through steam gasification of solid organic raw materials.
[0044] For example, a method provided by the present disclosure includes two parallel solid heat carrier circulations each of which can be independently optimized and controlled, wherein the circulated solid heat carrier is divided into two parts with different average particle size each. The part with smaller particle size is used as heating medium to heat solid organic raw material, which is thereby rapidly pyrolyzed; and the other part with larger particle size is used as heating medium, catalyst and moving particle filter material for the catalytic steam gasification of gaseous product including tar and low-carbon hydrocarbon generated from pyrolysis and capturing dust entrained in gaseous product generated from pyrolysis.
[0045] With the aid of the circulation of a solid heat carrier, a riser and combustion reactor can be tandem connected with parallel moving bed pyrolysis reactor and moving bed gasification reactor, respectively, so as to combine the three into one gasification system. The method achieves the respective independent control over (1) pyrolysis of solid organic raw material, (2) steam-involved decomposition and conversion (also known as gasification) of the gaseous product (including tar and hydrocarbon gas) generated from pyrolysis, and (3) independent control of combustion reaction of solid product generated from pyrolysis which provides the required heat for pyrolysis of raw material and the steam-involved decomposition and conversion of pyrolysis gas product. The method features normal-pressure operation and a simple process, and thus is suitable for the gasification and co-gasification of various high-volatile solid organics such as raw materials containing a relatively large amount of moisture, mineral substance, and sulfur.
[0046] A circulated solid heat carrier is subjected to size grading and allocated to moving bed pyrolysis reactor and moving bed gasification reactor which are disposed in parallel, with which the optimization of running conditions of both moving bed pyrolysis reactor and moving bed gasification reactor can be achieved. That is, the solid heat carrier with small particle sizes is applied to pyrolysis reactor to achieve rapid pyrolysis of raw materials. Meanwhile, the solid heat carrier with larger particle sizes is applied to moving bed gasification reactor, which allows the moving bed gasification reactor to have smaller bed layer resistance, and therefore achieve more efficient decomposition and conversion of tar and low-carbon hydrocarbon and hot dust-removing, on the premise of suitable catalyzing gasification effect. As such, the conversion of the organic substances in solid organic raw material into hydrogen-rich gas—a clean target product—can be maximized.
[0047] By using high volatile raw materials in combination with raw materials that achieve relatively high yield of solid product generated from pyrolysis which has high carbon content, i.e. using a co-gasification method, a solid product with desired quantity and carbon residue content can be generated from pyrolysis. The reaction system can be provided with heat required through the combustion of said solid product, such that energy balance of reaction system can be achieved without externally-provided heat. Since there is no need to combust solid organic raw materials directly for heat supply, an oriented transfer of hydrogen from raw materials to the product, hydrogen-rich gas, can be maximized.
[0048] After being connected in parallel, multiple moving bed pyrolysis reactors and corresponding moving bed gasification reactors may be connected with a riser and combustion reactor in tandem. By doing so, production capacity of the system can be efficiently improved and limitations of low production capacity of a single moving bed pyrolysis reactor can be overcome.
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] FIG. 1 is a schematic diagram showing an example method provided by the present disclosure for preparing hydrogen-rich gas through steam gasification of solid organic raw materials;
[0050] FIG. 2 is a schematic diagram showing an example method provided by the present disclosure for preparing hydrogen-rich gas through steam gasification of solid organic raw materials (including carbon-burning regenerator);
[0051] FIG. 3 is a schematic diagram showing an example system having parallel moving bed pyrolysis reactors and used for implementing methods of the present disclosure for preparing hydrogen-rich gas through steam gasification of solid organic raw materials;
DETAILED DESCRIPTION
[0052] Example embodiments of the present disclosure are further illustrated below by referring to the Figures and specific embodiments.
[0053] The rapid co-gasification of white pine chips and lignite is performed in the experiment system with a processing scale of 1 kg/h, and the operating principle of this experiment system is the same with that shown in FIG. 1 . The air-dry basis moisture, air-dry basis volatile matter and particle size of the first raw material white pine chips and the second raw material lignite are respectively 5.0%, 77.7%, less than 2 mm and 27.9%, 35.1%, less than 1.2 mm. Before the experiment, raw materials are dried for 3 hours at temperature of 105˜110° C. in oven. Olivine or olivine-supported nickel-based catalyst particles with particle size of 0.2˜1.2 mm is employed as circulated solid heat carrier.
[0054] After drying, the white pine chips and lignite are respectively fed into a secondary screw feeder at fixed or fixable quantities from each raw materials storage tank via corresponding primary screw feeders; both of the two materials are fed in a feeding rate of 250 g/h. The mixture of white pine chips and lignite is rapidly transported and fed from the secondary screw feeder to an internally disposed stirring mixer which locates at the upper portion of moving bed pyrolysis reactor 2 . Afterwards, the mixture is rapidly mixed with high temperature circulated solid heat carrier from solid heat carrier grading-dedusting device 1 , the most probable particle size of which is about 0.5 mm, and rapidly falls into reacting section which locates at the lower portion of moving bed pyrolysis reactor 2 to perform pyrolysis reaction.
[0055] Solid material level of moving bed pyrolysis reactor 2 is measured with an impeding level probe. The flow of solid heat carrier fed into pyrolysis reactor is controlled by a valve which connects solid heat carrier grading-dedusting device 1 and moving bed pyrolysis reactor 2 ; the flow of the mixture of solid heat carrier which leaves the pyrolysis reactor and solid product generated from pyrolysis is controlled by a valve configured at the pipeline which connects pyrolysis reactor 2 and the bottom of riser and combustion reactor 4 ; through the cooperation of the foregoing two valves, the solid material level of pyrolysis reactor can be controlled around 20 mm below the pyrolysis gas outlet.
[0056] An overheated steam inlet is disposed at the lower portion of moving bed pyrolysis reactor 2 . The overheated steam fed into moving bed pyrolysis reactor 2 with overheat temperature of 450° C. passes through the layer comprising solid heat carrier and solid product generated from pyrolysis, and goes upwards. During this process, the steam is further heated by solid product generated from pyrolysis and solid heat carrier, and at the same time, the gaseous product generated from pyrolysis is carried by and leaves solid material lay of moving bed pyrolysis reactor together with the steam.
[0057] The gaseous product of pyrolysis of raw materials in moving bed pyrolysis reactor is fed to moving bed gasification reactor 3 under the pumping effect of a vacuum pump which is disposed downstream of condensation-cooling system 5 . The mixture of solid product generated from pyrolysis of raw materials in pyrolysis reactor 2 and solid heat carrier is quantitatively fed to the mixing and pre-fluidizing section at the bottom of riser and combustion reactor 4 through pipeline valve under the effect of gravity.
[0058] Moving bed gasification reactor 3 is a radial moving bed, within which a circinate moving solid heat carrier particle layer passage—which is formed by surrounding internal net and external net—may be disposed. A central distributing gas passage is inside the internal net, and a joining gas passage is between external net and the outer wall of moving bed gasification reactor 3 . High temperature circulated solid heat carrier from solid heat carrier grading-dedusting device 1 with the most probable particle size of about 0.7 mm continuously flows through circinate moving particle layer passage, the flow quantity and stay time of which can be controlled by the pipeline valve which connects moving bed gasification reactor 3 and the bottom of riser and combustion reactor 4 . Gaseous product generated from pyrolysis enters into the central distributing gas passage of moving bed gasification reactor 3 from the upper portion thereof. After passing through the circinate solid heat carrier moving particle layer in cross current mode, the gaseous product is gathered at the joining gas passage and fed into condensation-cooling system 5 through the gas outlet pipeline which locates at the upper portion of moving bed reactor 3 .
[0059] Condensation-cooling system 5 may operate in a mode of indirect condensation-cooling, and may include two sections of circulated ice water condenser and two sections of circulated low temperature ethanediol (−10° C.) cooler in tandem. The hot gas from moving bed gasification reactor 3 flows through the foregoing four sections of condensation-cooling reactor, wherein the condensable matter (water and little amount of tar) is condensed and collected in the liquid storage tank at the bottom of each section of condensation-cooling reactor. After cooling, the gas is fed into a filter filled with degreasing cotton to capture the residual tar fog or aerogel. Then, the gas is fed to gasometer through vacuum pump.
[0060] The mixture of solid heat carrier from moving bed pyrolysis reactor 2 and the solid product generated from pyrolysis joins with the solid heat carrier from moving bed gasification reactor 3 at the pre-fluidizing section at the bottom of riser and combustion reactor 4 . The structure schematic diagram of the pre-fluidizing section at the bottom of riser and combustion reactor 4 is shown in FIG. 3 . Besides the main function of rising air, a second air inlet is disposed to assist the pre-fluidization of solid material.
[0061] The temperature of the hot air fed into the bottom of riser and combustion reactor 4 may be controlled (e.g., at about 400° C.). During the rising process of the mixture of solid heat carrier and solid product generated from pyrolysis by hot air, carbon residue on the solid product generated from pyrolysis and carbon deposit attached to solid heat carrier are fully combusted, and at the same time, the solid heat carrier is heated. Afterwards, high temperature solid heat carrier together with flue gas dust-bearing hot flue gas leaves from the upper portion of riser and combustion reactor 4 , and is fed into solid heat carrier grading-dedusting device 1 .
[0062] Solid heat carrier grading-dedusting device 1 comprises internal and external cylinders which are cone-shaped at the bottom, and each of which has a solid heat carrier outlet at the bottom end thereof. The solid heat carrier outlets respectively lead to moving bed pyrolysis reactor 2 and moving bed gasification reactor 3 . The internal cylinder has a height of about ⅓-⅔ of the height of the external cylinder, and is open at the top end. The top end of the external cylinder is closed, and has an outlet for dust-bearing hot flue gas disposed at the central portion thereof. An inlet for the mixture of hot flue gas and high temperature solid heat carrier is in the horizontal tangent direction of the external cylinder inner wall at the top of solid heat carrier grading-dedusting device 1 .
[0063] After the entering of hot flue gas carrying high temperature solid heat carrier along the tangent direction from riser and combustion reactor 4 into solid heat carrier grading-dedusting device 1 , under the effect of inertia force and centrifugal force, the solid heat carrier with larger average particle size mainly falls into the cone-shaped section at the bottom of external cylinder, and the solid heat carrier with smaller average particle size mainly falls into the cone-shaped section at the bottom of internal cylinder, while fine dust together with hot flue gas leaves from the hot flue gas outlet at the top end and is emitted after further dust-removing and cooling.
[0064] Table 1 shows the results of two experiments, which employ 900° C. calcined olivine and calcained olivine-supported nickel catalyst (mass fraction of NiO is 5%) as circulated solid heat carrier, respectively, and white pine chips and lignite are continuously fed for 3 hours. Other experiment conditions are: circulating rate of solid heat carrier passing through moving bed pyrolysis reactor is 2 kg/h; circulating rate of solid heat carrier passing through radial moving bed gasification reactor is 3 kg/h; the temperature of riser and combustion reactor is 870° C.; the temperature of solid heat carrier grading-dedusting device is 870° C.; the temperature of moving bed pyrolysis reactor is 600° C.; the temperature of radial moving bed gasification reactor is 850° C.; mass ratio of steam/(lignite+white pine chips) is 0.64. After being collected by gasometer, hydrogen-rich gas product is subjected to composition and content analysis with gas chromatography. The method for analyzing liquid product is shown below: after the experiment, tetrahydrofuran (THF) is employed to wash the condensation-cooling system and collects liquid product. The collected liquid mixture (water+tar+THF) is evaporated by rotary evaporator at 40° C. and reduced pressure, which is to remove THF to get the mixture of tar and water; ethyl acetate is employed to extract tar, and the mixture of ethyl acetate and tar is evaporated by rotary evaporator at 45° C. and reduced pressure, which is to remove ethyl acetate to get tar, and then the quantity of tar and water is measured and calculated.
[0065] Experiment results show that, as compared with calcined olivine, as circulated solid heat carrier, calcined olivine-supported nickel catalyst exhibits relatively high activity in tar removal and methane reforming of gaseous product, and the gas yield and the content of H 2 and CO of the product gas are improved, wherein the decomposition-removal rate of tar and the conversion rate of methane are respectively 94.4% and 98.2%. Within the collected liquid product, no significant amount of dust is detected.
[0000]
TABLE 1
gasification ability comparison of
different solid heat carrier catalysts
Olivine-
supported
Solid heat carrier
nickel
Olivine
Gas composition (vol. %)
H 2
46.0
38.0
CO
25.0
15.3
CO 2
28.7
33.8
CH 4
0.2
11.9
Hydrogen-rich gas yield
(Nm 3 /kg daf.)
1.39
0.89
Tar content in product gas
(g/Nm 3 )
0.44
7.89
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The present disclosure provides a method for preparing hydrogen-rich gas by solid organics. For example, solid organic raw materials are heated in a pyrolysis reaction device to perform pyrolysis reaction, and gaseous product generated from the pyrolysis reaction performs gasification with steam in a moving bed gasification reaction device to generate hydrogen-rich product. The present disclosure also provides a system for preparing hydrogen-rich gas by solid organics, and the system may include a solid heat carrier grading-dedusting device; a pyrolysis reaction device; a moving bed gasification reaction device; and a riser and combustion reactor. The present disclosure may operate at atmospheric pressure, and the technology is simple and suitable for the gasification and co-gasification of various high-volatile solid organics, such as raw materials containing a relatively large amount of moisture, mineral substance, and sulfur content.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the priority benefit of French patent application number 12/52996, filed on Apr. 2, 2012, which is hereby incorporated by reference to the maximum extent allowable by law.
BACKGROUND
1. Technical Field
The present disclosure relates to an energy harvesting device and to a method of forming such a device. In particular, the present disclosure relates to a device that converts thermal energy into electrical energy.
2. Discussion of the Related Art
It has been proposed to use a bimetal plate, which changes shape under varying temperature conditions, in combination with a layer of piezoelectric material, to convert thermal energy into electrical energy.
FIG. 1 substantially reproduces FIG. 2 of U.S. patent application 2011/083714. As illustrated, a curved bimetal plate 100 comprises a support layer 102 , which changes shape in response to temperature variations. Plate 100 is shown having a first shape in the form of an arch, and for example changes shape to the form of an inverted arch when its temperature changes. A layer 104 of piezoelectric material is superposed over the support layer 102 . A piezoelectric material is one that has the property of generating a voltage difference between its main surfaces that varies depending on the stress applied to it. During a shape change of the curved metal plate 100 , a stress S occurs in the piezoelectric layer 104 , represented by arrows in FIG. 1 , resulting in variations in the voltage signals V − and V + present on the top and bottom surfaces of the piezoelectric layer 104 . The curved metal plate 100 is, for example, positioned in a cavity between hot and cold walls, such that its middle section contacts with the hot and cold walls when the curved plate 100 assumes its respective shapes. This results in a periodic shape change of the metal plate 100 , leading to the generation of a periodic voltage signal from which electrical energy can be extracted.
There is a need in the art for a simple and low cost energy harvester that operates based on the above principles and that can provide an efficient conversion of thermal to electrical energy in a range of different environments.
SUMMARY
It is an aim of embodiments to at least partially address one or more needs in the prior art.
According to one aspect, there is provided an energy harvester comprising: first and second sheets; and a plurality of walls, each wall being sandwiched between the first and second sheets and surrounding a cavity, wherein each cavity houses at least one curved plate adapted to change from a first shape to a second shape when its temperature reaches a first threshold and to return to the first shape when its temperature falls to a second threshold lower than said first threshold.
According to one embodiment, each of said cavities houses a single curved plate.
According to another embodiment, each of said cavities houses a plurality of curved plates interconnected by fingers to form a matrix.
According to another embodiment, between said first and second sheets, there is a space separating a first of said walls from a second of said walls.
According to another embodiment, the energy harvester further comprises, within each of said cavities, a printed layer of piezoelectric material adapted to be deformed by said curved plate.
According to another embodiment, said piezoelectric layer is printed onto an inner surface of each cavity on a surface of said first sheet.
According to another embodiment, said piezoelectric layer is printed on a surface of each curved plate.
According to another embodiment, said inner walls are arranged in at least one column and in at least one row.
According to another embodiment, each of said curved plates comprises a layer of a first metal superposed by a layer of a second metal, the first and second metals having different coefficients of expansion.
According to another embodiment, each of said curved plates is formed of a shape-memory material.
According to a further aspect, there is provided a method of manufacturing an energy harvester comprising: forming a plurality of walls on a first sheet of material, each wall defining an opening which it surrounds; placing at least one curved plate into each of said openings, each curved plate being adapted to change from a first shape to a second shape when its temperature reaches a first threshold and to return to the first shape when its temperature falls to a second threshold lower than said first threshold; and sandwiching each of said walls between said first sheet and a second sheet of material.
According to one embodiment, the method comprises placing a matrix of curved plates into each of said openings.
According to another embodiment, the method further comprises printing a layer of piezoelectric material on either: each of said curved plates; or each of a plurality of zones on the surface of said first sheet, each opening being aligned over one of said zones.
According to another embodiment, the method further comprises printing, on said first sheet, interconnecting tracks comprising a plurality of electrodes adapted to make contact with each of said piezoelectric layers.
According to another embodiment, the material forming each of said first and second sheets is a plastic or insulated metal having a thickness of between 0.5 mm and 5 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other purposes, features, aspects and advantages will become apparent from the following detailed description of embodiments, given by way of illustration and not limitation with reference to the accompanying drawings, in which:
FIG. 1 (described above) illustrates a curved metal plate in order to demonstrate a technique for thermal energy harvesting;
FIG. 2 is a cross-section view illustrating part of a thermal energy harvester according to an example embodiment;
FIG. 3 is a cross-section, taken in a horizontal plane, of the energy harvester of FIG. 2 according to an example embodiment;
FIGS. 4A to 4E are perspective views of an energy harvester at various stages during its manufacture according to an example embodiment;
FIG. 5 is a cross-section view illustrating part of a thermal energy harvester according to an alternative embodiment; and
FIG. 6 is a perspective view illustrating a matrix of curved plates according to an example embodiment.
It should be noted that the structures illustrated in the various figures are not drawn to scale, the thicknesses of certain layers in particular being shown to be disproportionately large to aid representation.
Furthermore, throughout the following description, relative orientations such as “top surface”, “bottom surface”, “upper” and “lower” are assumed to apply when the corresponding structure is orientated as shown in the drawings.
DETAILED DESCRIPTION
FIG. 2 is a cross-section view illustrating a portion of an energy harvester 200 according to an example embodiment. Two curved plates labelled 202 are positioned in corresponding cavities 206 , 208 of the energy harvester 200 . For example, each of these plates 202 corresponds to the curved bimetal plate 100 of FIG. 1 described above, except that it does not comprise the layer 104 of piezoelectric material superposed over the support layer 102 . Instead, a top wall of each cavity 206 , 208 is formed by a corresponding layer of piezoelectric material 210 .
The curved plates 202 are, for example, bimetal plates, formed of a layer of a first metal superposed by a layer of a second metal, the first and second metals having different coefficients of expansion. For example, the metal of each layer is one of TiN, aluminium, copper, tungsten, FeNi and an alloy of any of these metals. Alternatively, one or both layers could be formed of non-metals.
For example, the width and length of the curved plates are in the range of 1 μm to 10 mm. A method of forming curved plates having relatively small dimensions is for example discussed in more detail in U.S. Pat. No. 8,951,425, filed on the same day as the present patent application and having the same inventors, which is hereby incorporated by reference in its entirety.
In some embodiments, the curved plates 202 are formed such that their change of shape in response to temperature variations is progressive, for example between the two shapes of the plates 202 illustrated in cavities 206 and 208 of FIG. 2 .
In alternative embodiments, the curved plates 202 are bi-stable, such that they flip rapidly from one shape to another when heated to a first temperature threshold, and back to their original shape when cooled to a second temperature threshold, lower than the first temperature threshold. For example, the curved plates 202 may comprise, as one of its layers, a shape-memory material, for example a nickel and titanium alloy. Such a material for example comprises two crystal phases, and is capable of having two stable shapes. Alternatively, the curved plate 202 may have an inward force applied to its ends by one or more springs, resulting in such a bi-stable effect.
The structure of the energy harvester 200 for example comprises an upper sheet of material 214 and a lower sheet of material 216 . For example, the upper and lower sheets 214 , 216 are each formed of a plastic sheet or of an insulated metal sheet. The sheets 214 , 216 are for example flexible and each have a thickness of between 0.5 mm and 5 mm, depending on the size of the energy harvester 200 and the desired extent of flexibility.
On the left-hand side of the structure shown in FIG. 2 , a peripheral wall 218 , for example formed of gum, silicon, silicon dioxide, or porous-silicon, separates the sheets 214 and 216 . The peripheral wall 218 for example extends around the whole device close to the edges of the sheets 214 and 216 , as will be described in more detail below. For example, the separation between the inner surfaces of the upper and lower sheets 214 , 216 is in the range of 0.5 mm to 20 mm.
The piezoelectric layers 210 of each cavity 206 , 208 are positioned at regular intervals on the inner surface of the upper sheet 214 . An inner wall 220 , also for example formed of gum, silicon, silicon dioxide, or porous-silicon for example surrounds each cavity 206 , 208 , and contacts the respective piezoelectric layers 210 above, and contacts the top surface of the lower sheet 216 below.
The peripheral wall 218 , and the inner wall 220 corresponding to the left-hand cavity 206 in FIG. 2 , are separated by a distance d 1 , for example of between 1 and 20 mm. The inner walls 220 corresponding to neighbouring cavities 206 , 208 in FIG. 2 are separated by a distance d 2 also of, for example, between 1 and 20 mm.
As represented by dashed lines extending from the right-hand edge of the structure of FIG. 2 , the structure may continue beyond what is illustrated in FIG. 2 , with one or more further cavities containing further curved plates 202 .
FIG. 3 illustrates an example of a cross-section view of the energy harvester 200 , in a horizontal plane represented by a dashed line A-A in FIG. 2 , passing through the peripheral wall 218 and inner walls 220 .
In the example of FIG. 3 , the energy harvester 200 comprises 21 curved plates 202 , each housed in a corresponding cavity, and arranged in 3 rows and 7 columns. Of course, in alternative embodiments, the energy harvester could comprise any number of curved plates. In some embodiments, hundreds, thousands or even millions of curved plates may be provided, each housed in a corresponding cavity or grouped into cavities. In particular, in some embodiments, each cavity houses a single curved plate. In alternative embodiments described in more detail with reference to FIG. 6 , each cavity houses a plurality of curved plates formed in a matrix.
An advantage of housing the curved plates in cavities, each cavity being surrounded by an inner wall 220 , is that the structure may be relatively flexible. Furthermore, an advantage of arranging the inner walls 220 in rows and columns is that this adds to the flexibility of the structure. In alternative embodiments, rather than being arranged in rows and columns, the inner walls 220 could be arranged in different patterns.
In plan view, the energy harvester 200 is for example rectangular in shape, and the peripheral wall 218 thus extends in a rectangle around the edge of the device. Furthermore, each of the inner walls 220 also for example extends around the corresponding cavity in the form of a rectangle, the rectangle being square in the example of FIG. 3 .
Such a rectangular shape of the inner walls 220 is well adapted to rectangular plates 202 . In alternative embodiments, the curved plates 202 and inner walls 220 could have other shapes, for example circular or hexagonal.
A method of forming an energy harvester similar to that of FIGS. 2 and 3 will now be described with reference to FIGS. 4A to 4E .
FIGS. 4A to 4E are perspective views of an energy harvester 400 at various stages of manufacture, in this example comprising 35 plates 202 arranged in seven columns and five rows.
With reference to FIG. 4A , in a first step, a grid of conductive tracks is printed or otherwise deposited on the surface of the upper sheet 214 of the structure of FIG. 2 . The top surface of the sheet 214 shown in FIG. 4A corresponds to the bottom surface of the sheet 214 orientation as shown in FIG. 2 .
In the example of FIG. 4A , the grid of conducting tracks comprises seven tracks 402 to 414 formed in columns. Each of the tracks 402 to 414 comprises five regularly spaced electrodes 416 , in this example formed as “U” shaped tracks. Thus there are a total of 35 electrodes. The respective ends of the tracks 402 to 414 are coupled together by respective tracks 418 and 420 running perpendicular to the column tracks 402 to 414 . The track 420 is for example coupled to a connection terminal 422 close to an edge of the sheet 214 .
For example, the conductive tracks could be formed of copper or another suitable conducting material, and printed using PCB (printed circuit board) techniques, which are well known in the art.
FIG. 4B illustrates the upper sheet 214 after a subsequent step in which a piezoelectric layer 210 has been formed over each electrode 416 . For example, the piezoelectric material is formed of PZT (lead zirconate titanate), ZnO or a compound based on lead and zirconium. The piezoelectric layers 210 could be coated, deposited or printed. For example techniques for printing such a material are discussed in more detail in the publication entitled “Processing of Functional Fine Scale Ceramic Structures by Ink-Jet Printing”, M. Mougenot et al., the contents of which is hereby incorporated by reference to the extent permitted by the law.
In some cases, the printing or depositing of the piezoelectric layers 210 may be followed by a baking step, for example at a temperature of 200° C. or less.
FIG. 4C illustrates the structure after a subsequent step in which a further grid of conducting tracks is formed over the surface of upper sheet 214 , this further grid being very similar to the grid discussed above with reference to FIG. 4A . In particular, the further grid of conducting tracks comprises electrodes 424 , one of which is formed over each piezoelectric layer 210 . To prevent electrical contact between the conductive tracks of each of the superposed grids, an insulating layer is for example deposited in some areas prior to forming the further grid. The further grid of conducting tracks is coupled to a further terminal 426 near an edge of the upper sheet 214 .
The further grid of conducting tracks comprising the electrodes 424 is for example printed or coated, for example using well known techniques, such as those used to print RFID (Radio Frequency Identification) antennas.
FIG. 4D illustrates yet a further step in which the peripheral wall 218 and inner walls 220 are formed over the surface of the upper sheet 214 , and a curved plate 202 is positioned within each inner wall 220 . In particular, the step of placing each of the inner walls on the surface of the upper sheet 214 for example defines a corresponding opening 428 surrounded by the inner wall, and into which the plates 202 are placed.
In some embodiments, the curved plates 202 are individual elements. Alternatively, they could form a matrix, being interconnected by one or more fingers. Such fingers could be embedded in the inner walls 220 .
FIG. 4E illustrates a final step of the method in which the lower sheet 216 is glued to the structure opposite the upper sheet 214 to form the finished energy harvester 400 . In some embodiments, this final gluing step may be performed in a partial vacuum such that the cavities defined by each inner wall 220 are at a partial vacuum, and likewise the spacing between the inner walls 220 in the area between the sheets 214 , 216 is also for example at a partial vacuum. Such a feature improves the insulation between the upper and lower sheets 214 , 216 .
The terminals 422 and 426 (not illustrated in FIG. 4E ) are for example coupled to energy recuperation circuitry 430 , which recuperates the electrical energy resulting from the voltage changes across the surfaces of the piezoelectric layers 210 . This electrical energy is for example used to charge a battery and/or supply a load (not illustrated in the figures).
As represented in FIG. 4E , due in part to the form of the inner walls 220 , the resulting energy harvester 200 is for example relatively flexible, for example being able to be bent around pipes or placed in contact with other uneven surfaces. Such flexibility improves the thermal contact between the energy harvester 400 and a heat source, and thus leads to a higher thermal gradient across the energy harvester. This in turn leads to greater energy recuperation. Indeed, the warmer the lower sheet 216 , the faster the curved plates 202 will be heated and change shape, thereby increasing the mechanical power generated by the curved plates and thus the electrical power generated by the piezoelectric layers 210 .
The surface area of the device 200 could be anything from a few square millimeters to several square meters. For example, in some embodiments the device 200 has a surface area of at least 0.1 square meters.
In an alternative embodiment, the upper sheet 214 and/or lower sheet 216 could comprise features contributing to the final structure. For example, the inner walls 220 and/or peripheral wall 218 could at least partially be formed of a protrusion from the surface of the lower sheet 216 .
FIG. 5 is a cross-section view illustrating a portion of an energy harvester 500 according to an alternative embodiment. The energy harvester 500 is very similar to the energy harvester 200 of FIG. 2 , and like features have been labeled with like reference numerals and will not be described again in detail.
In energy harvester 500 , the piezoelectric layers 210 are removed, the inner walls 220 extending to the underside of the upper sheet 214 . Instead, each of the curved metal plates 202 comprises a piezoelectric layer 502 , which is for example similar to the layer 104 of FIG. 1 . Furthermore, an electrode 504 is for example deposited or coated over the piezoelectric layer. In one example, the electrical signals generated by such a piezoelectric layer 502 are recuperated by electrodes (not illustrated in FIG. 5 ), similar to electrodes 416 , 424 described above, printed on the inner surfaces of the upper and lower sheets 214 , 216 . As illustrated, a connecting wire 506 for example couples the electrode 504 to such an electrode formed on the underside of the upper sheet 214 , and a connecting wire 508 for example couples the metal layers of curved plate 202 to an electrode formed on the top side of the lower sheet 216 .
FIG. 6 is a perspective view illustrating a portion of the structure of FIG. 3 in more detail according to an example in which each of the cavities defined by the inner walls 220 houses a matrix 600 of curved plates 202 . In the example of FIG. 6 , the matrix 600 comprises eight plates arranged in two columns and four rows, although in alternative embodiments the matrix could comprise any number of curved plates, such as hundreds or thousands of plates arranged in an appropriate number of columns and rows.
As illustrated in FIG. 6 , each of the curved plates 202 is for example attached by a single finger 602 to a common interconnecting rail 604 . In this way, despite being interconnected, each of the plates 202 may flip from one bi-stable state to another independently of the other plates.
The interconnecting fingers 602 and rail 604 are, for example, all formed of the same layered structure as the curved plates 202 . The matrix 600 is, for example, formed by the method described in relation to FIGS. 5 and 6 of U.S. Pat. No. 8,951,425.
While a number of specific embodiments of a method and device have been described herein, it will be apparent to those skilled in the art that there are various modifications and alterations that could be provided.
For example, it will be apparent to those skilled in the art that while a few examples of arrangements of curved plates within an energy harvester have been described, other arrangements of the plates would be possible.
Furthermore, while rectangular curved plates have been described, in alternative embodiments, the plates could have other forms, such as circular or hexagonal.
Furthermore, the “U” shaped form of the electrodes 416 , 424 is merely one example, many other forms being possible.
The various features described in relation with the embodiments described herein could be combined, in alternative embodiments, in any combination.
Having thus described at least one illustrative embodiment of the invention, various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention is limited only as defined in the following claims and the equivalents thereto.
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An energy harvester including first and second sheets; and a plurality of walls, each wall being sandwiched between the first and second sheets and surrounding a cavity, wherein each cavity houses at least one curved plate adapted to change from a first shape to a second shape when its temperature reaches a first threshold and to return to the first shape when its temperature falls to a second threshold lower than said first threshold.
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FIELD OF THE INVENTION
This invention relates to the field of semiconductor apparatus and, more particularly, to methods of fabricating electrodes for transistors.
BACKGROUND OF THE INVENTION
In the prior art, cobalt silicide electrodes have been suggested for commercial use as electrode metallization contacts to silicon in semiconductor transistor devices, particularly insulated gate field effect transistor devices. When a cobalt silicide electrode metallization contact to silicon is initially made at a temperature below about 550° C., such an electrode is essentially formed as cobalt monosilicide (CoSi); and if, as ordinarily desired during further processing thereafter, the temperature of the device being fabricated is subsequently raised to a value above about 600° C., then the cobalt monosilicide is converted into cobalt disilicide (CoSi 2 ) and this conversion produces an increase in the volume of the cobalt silicide. Such an increase in volume can cause undesirable strains unless there is sufficient empty space (such as that provided by an exposed surface of the cobalt silicide) into which the cobalt disilicide can expand.
If a contact to silicon is initially formed directly as cobalt disilicide by heating cobalt metal in contact with the silicon to a temperature above about 550° C. or 600° C., then the subsequent need to raise the processing temperature to a value above 900° C.--for such purposes as gettering of impurities, or annealing of damage, or flowing of phosphosilicate glass (P-glass)--causes undesirable grain growth in the cobalt disilicide as well as undesirable migration of silicon from the underlying source and drain regions to the cobalt disilicide electrode, which migration deteriorates the transistor operation. Furthermore, heating of the cobalt disilicide to temperatures above about 900° C. increases the resistance of the cobalt disilicide--which is especially undesirable for the gate electrode--probably because of intermixing of the cobalt disilicide with silicon. In addition, at temperatures above about 600° C., pure cobalt itself reacts with the silicon dioxide ordinarily present on the wafer in regions removed from the cobalt silicide electrode, whereby undesirable compounds are formed that are difficult to remove differentially, i.e., while leaving intact the cobalt silicide as ordinarily desired in patterning the structure by differential etching. Also, above about 600° C., cobalt has a tendency to draw, by diffusion into itself, any nearby silicon or phosphorus, which undesirably lengthens the gate electrode and deteriorates any phosphorus doped glass (P-glass). It would, therefore, be desirable to have a method of forming cobalt disilicide electrode contacts to silicon which alleviates these problems.
SUMMARY OF THE INVENTION
Cobalt disilicide electrode metallization contacts to underlying silicon (either polycrystalline or monocrystalline) are formed, in accordance with the invention, by sintering (heat-treating) a cobalt silicide layer in contact with silicon at a temperature of about 700° C. or more in an oxidizing ambient, preferably containing at least about 1 percent oxygen by volume. Thereby cobalt disilicide electrodes form coated with silicon dioxide, the silicon of said dioxide having diffused thereto from the underlying silicon through the cobalt silicide, so that the resulting cobalt disilicide electrodes are relatively stable during further processing steps. Alternatively, the ambient in which the cobalt silicide layer is sintered at 700° C. or more need not be oxidizing, in which case the resulting cobalt disilicide is coated by a separate deposition step with a layer of silicon dioxide. By "cobalt-rich silicide" is meant compounds of cobalt silicide (such as Co 2 Si) having a cobalt to silicon atomic ratio greater than that of cobalt monosilicide. Mixtures of compounds of cobalt monosilicide and cobalt-rich silicide, whether or not mixed with cobalt disilicide, are denoted simply by "cobalt silicide."
In a specific embodiment of the invention, an insulated gate field effect transistor device structure is fabricated in a silicon semiconductor substrate or body, with source and drain electrode metallization contacts to the silicon body, or with gate electrode metallization contacts to a polycrystalline silicon gate, or with both--such contacts being essentially cobalt disilicide. These metallization contacts are formed by first sintering cobalt on the silicon (body or gate) at a relatively low temperature (typically about 450° C.), and thereafter sintering at a relatively high temperature (above about 700° C.) in an oxidizing ambient typically containing about 1 percent oxygen.
More specifically, in accordance with the invention, a cobalt metal layer is deposited to a desired thickness on a major surface of a patterned semiconductor silicon wafer in which the transistor is being fabricated, the degree or stage of patterning of the wafer at the time of this cobalt deposition depending upon whether cobalt silicide metallization of a gate electrode or of source and drain electrodes is desired. After deposition of the metal layer of cobalt, the metal is sintered at the relatively low temperature (about 450° C.) to the underlying silicon or polysilicon (polycrystalline silicon) with which the cobalt layer is in contact, in order to form cobalt silicide. The unreacted cobalt, that is, the cobalt in contact with non-silicon portions (typically silicon dioxide or P-glass portions) is removed by selective etching which removes the cobalt but which does not remove the cobalt silicide. Thereafter--but before any further processing involving heating (which would produce undesirable strains due to volume changes accompanying the formation of cobalt disilicide)--the cobalt silicide is again sintered, this time in the oxidizing ambient (typically about 2 percent oxygen) at the relatively high temperature (typically about 700° C. to 950° C. or more) to form electrodes of cobalt disilicide.
When forming further source and drain electrode metallization, after forming the cobalt disilicide electrodes in accordance with the invention, advantageously in-situ doped polysilicon is deposited on the cobalt disilicide, in order to provide good step coverage for a further deposition of aluminum metallization on the polysilicon and, at the same time, to protect against undesirable reactions ("spiking") of the aluminum with the cobalt disilicide in the source and drain regions which can otherwise result on further heat treatments of the wafer at or above about 400° C.
Resistivities of the resulting cobalt disilicide electrodes made in accordance with the invention can be as low as 20 micro-ohm cm, with contact resistances substantially equal to or lower than that obtained by the use of aluminum directly in contact with silicon or polysilicon. Moreover, these cobalt disilicide electrodes are suitably stable against undesired migration of cobalt which would otherwise occur during further transistor processing steps at the relatively high temperatures (above about 600° C.) ordinarily required for gettering of impurities, chemical vapor deposition of phosphosilicate glass for electrical isolation, or chemical vapor deposition of silicon nitride for sealing purposes. It should be understood, however, that the relatively high temperature (700° C. to 900° C. or more) at which the cobalt disilicide is stabilized in the oxidizing ambient, in accordance with the invention, need not be as high as the highest subsequent processing temperature to be used.
It is theorized that the oxidizing property of the ambient in which the cobalt disilicide is stabilized at or above 700° C., in accordance with the invention, is useful for preventing the formation of cobalt monosilicide or cobalt-rich silicides and for providing a thin (about 50 to 70 Angstroms) coating of silicon dioxide on the cobalt disilicide layer, this coating being useful for suppressing subsequent interdiffusion of the cobalt disilicide with any nearby silicon or phosphorus. The utility of the invention, of course, is not dependent on the correctness of this theory.
BRIEF DESCRIPTION OF THE DRAWING
This invention, together with its advantages, features, and objects, can be better understood from the following detailed description when read in conjunction with the drawings in which
FIGS. 1-6 depict, in cross-section, various stages of manufacture of an insulated gate field effect transistor in accordance with a specific embodiment of the invention.
Only for the sake of clarity, none of the drawings is to any scale.
DETAILED DESCRIPTION
In order to fabricate an insulated gate field effect transistor device structure 100 (FIG. 6), on a major surface of a p-type silicon wafer or body 11 (FIG. 1) are successively formed a field oxide layer 12, a gate oxide layer 13, a polysilicon layer 14, a silicon dioxide masking layer 15 patterned with apertures, and a cobalt metal layer 16. The polysilicon layer 14 has a thickness ordinarily in the range of about 2000 to 5000 Angstroms, typically about 3000 Angstroms. The cobalt layer 16 has a thickness ordinarily in the range of about 300 to 700 Angstroms, typically about 600 Angstroms. This cobalt layer 16 can be deposited, for example, by known Argon ion sputtering techniques at room temperature or by evaporation while the silicon body is held at about 200° C. to 250° C.--as described for example, in G. J. VanGurp et al., 46 Journal of Applied Physics, pp. 4308-4311 at pp. 4308-4309 (1975). Then the structure being fabricated is heated in an inert ambient, such as forming gas (nitrogen containing about 15 percent of hydrogen by volume) at one atmosphere, so that the cobalt layer 16 is heated to a first temperature in the range of about 400° C. to 550° C., typically about 450° C., typically for about two hours. As a consequence of this first heat treatment, the cobalt layer 16 is converted into a cobalt silicide layer 18 in regions overlying in direct contact with a thinned polysilicon layer portion 24 underlying an aperture in the silicon dioxide masking layer 15, whereas the cobalt layer 16 remains as a cobalt layer 26 (FIG. 2) in regions overlying the masking layer 15--that is, in regions overlying the complement of the exposed polysilicon portions. The cobalt layer 26 is then removed, as by an etch treatment of the structure with an acid solution--typically a 5:3:1:1 volume mixture of concentrated acetic, nitric, phosphoric, and sulfuric acids (C. J. Smithells, Metals Reference Handbook, Vol. 1, p. 328)--which leaves intact the cobalt silicide layer 18 (FIG. 3).
Next, the exposed portion of the silicon dioxide masking layer 15 is removed, as by selective etching with buffered hydrofluoric acid (BHF) using the cobalt silicide layer 18 as a protective mask against etching. Then the exposed portions of the polysilicon layer 14 are removed, as by plasma etching or by reactive ion etching, from regions complementary to the cobalt silicide layer 18 again using this cobalt silicide layer 18 as a protective mask against etching. Next, the exposed portions of silicon dioxide layer 13 are etched with a solution, such as commercial buffered hydrofluoric acid (30:1), that does not remove the cobalt silicide layer 18. The remaining thinned polysilicon layer portion 24 and a silicon dioxide layer portion 23 underlie the cobalt silicide layer 18. This cobalt silicide layer 18 is now to be converted into cobalt disilicide.
After cleaning the top surface of the structure, typically with commercial buffered hydrofluoric acid (30:1) for about 30 to 60 seconds, the structure being fabricated is then subjected, this time in an oxidizing ambient, to a second heat treatment at a second temperature of at least 700° C., ordinarily in the range of about 700° C. to 1000° C., typically about 900° C., for about one-half hour. This oxidizing ambient advantageously is an inert gas, such as argon, mixed with oxygen in a molar concentration in the range of about 1 percent to 5 percent, typically about 2 percent. As a consequence of this latter heating, the cobalt silicide layer 18 is converted into a cobalt disilicide layer 28 (FIG. 4).
It is important for most transistor device applications, particularly insulated gate field effect transistors, that the cobalt disilicide layer 28 does not penetrate down to the underlying silicon dioxide layer 23; therefore, a suitably large thickness should be selected for the polysilicon layer 14 (which combines chemically with the overlying cobalt layer 16 to form the cobalt silicide layer 18 and then the cobalt disilicide layer 28), so that some of the polysilicon layer 24 still remains underlying the cobalt disilicide layer 28. In this manner, also, the remaining polysilicon is available (by diffusion) for the formation, if desired, of silicon dioxide as an insulator on top of the cobalt disilicide.
Next, the n+ source and drain zones 21 and 22 are formed, as by conventional ion implantation and diffusion of donor impurities, using the combined cobalt disilicide layer 28 and the polysilicon layer as a protective (self-aligned) mask against introduction of impurities thereunder.
Next, a phosphosilicate glass (P-glass) layer and a chemical vapor deposited (CVD) silicon nitride layer are successively formed on the structure at elevated temperatures typically in the range of about 700° C. to 900° C., and about 700° C. to 800° C., respectively, as described in greater detail, for example, the concurrently filed application of Clemens and Sinha Ser. No. 296,832, filed Aug. 27, 1981, entitled "Stabilization of N-Channel Transistors by Chemical Vapor Deposited Silicon Nitride Layer." The CVD nitride layer is then isotropically etched, as by plasma etching, at selected locations that overlie those portions of the source and drain zones 21 and 22 where the source and drain electrode contacts to the silicon are to be formed. Thereby, a patterned CVD silicon nitride layer 26 (FIG. 5) is formed, useful for protecting the transistor to be formed from such contaminants as hydrogen. Then, the P-glass layer is selectively anisotropically etched (steep, substantially vertical sidewall), as by ion beam etching, in order to form a patterned P-glass layer 25 and to expose underlying portions of the source and drain zones 21 and 22.
Next, another cobalt layer--of thickness in the range of about 100 to 700 Angstroms, typically about 500 Angstroms--is deposited. The structure is then heated to the relatively low temperature--400° C. to 550° C., typically about 450° C. for one-half hour--so that this latter cobalt layer combines with the silicon to form cobalt silicide electrodes 31 and 32 at the exposed portions of the source and drain zones 21 and 22. The cobalt remaining at the complementary portions of the structure is removed, as by acid etching (for example, as described above in connection with the cobalt silicide layer 18), without removing the cobalt silicide. After cleaning the structure, typically with commercial buffered hydrofluoric acid (30:1), the cobalt silicide electrodes 31 and 32 are converted into cobalt disilicide electrodes 41 and 42 by heating as described above in conjunction with formation of the cobalt disilicide layer 28, i.e., by heating in an oxidizing ambient at a temperature preferable in the range of about 700° C. to 1000° C., typically about 900° C., for about half an hour. These cobalt disilicide electrodes 41 and 42 (FIG. 6) directly contact the source and drain zones 21 and 22, respectively.
Next, a polysilicon layer, preferably doped in situ (doped while being deposited) with phosphorus, is formed all over the top surface of the structure being fabricated. Then, in order to getter the impurities, the structure is heated to a temperature in the range of about 950° C. to 1000° C., typically in an ambient of phosphorus tribromide (PBr 3 ) vapor and about 2 percent oxygen in nitrogen, for about 30 minutes.
Then, a layer of aluminum is deposited--as by evaporation--on the last deposited polysilicon layer. By conventional masking and etching, the aluminum and polysilicon layers are selectively etched to form a polysilicon metallization layer 33 and an aluminum metallization layer 34 suitable for interconnection of the source and drain zones 21 and 22 of the transistor structure 100. The polysilicon layer 33 serves to provide good metallization step coverage and to furnish a desirable barrier against interdiffusion of aluminum and cobalt disilicide. Finally, a plasma deposited silicon nitride layer 35 is formed all over the top surface of the structure 100 in order to seal and protect the underlying device.
The phosphorus doped polysilicon layer 33 will be stable against undesirable intermixing with underlying cobalt disilicide so long as all further processing is done below about 950° C. In case the polysilicon metallization layer 33 is doped with boron instead of phosphorus, then undesirable instability will occur by reason of intermixing of the polysilicon with the underlying cobalt disilicide if any further processing is done above about 800° C.; therefore, all further processing in such a case of boron doping is preferably done at temperatures well below 800° C., such as about 500° C.
In a typical example by way of illustration only, approximate thicknesses of the various layers are:
Field oxide layer 12: 10,000 Angstroms
Gate oxide layer 13: 250 Angstroms
Polysilicon layer 14: 3,000 Angstroms
Masking oxide layer 15: 1,500 Angstroms
P-glass layer 25: 15,000 Angstroms
CVD nitride layer 26: 1,200 Angstroms
Polysilicon layer 33: 3,500 Angstroms
Aluminum layer 34: 10,000 Angstroms
Plasma deposited nitride layer 35: 12,000 Angstroms
It should be understood that the above recitation of various steps to form the structure 100 is intended to be illustrative only, and does not exclude the use of various refinements, substitutions, and additions, such as further cleaning and annealing steps as known in the art. Also, the CVD nitride layer 26 can be omitted in cases where the "hot electron" problem (caused by undesirable interactions involving hydrogen in the gate oxide, the hydrogen originating from the plasma deposited nitride layer 35) is not serious--for example, in cases where the source-to-drain operating voltage does not exceed about 5 volts.
Although the invention has been described in detail in terms of a specific embodiment, various modifications can be made without departing from the scope of the invention. For example, the first heat treatment of the cobalt can be at about 600° C. in the absence of an oxidizing agent in the ambient, in order to form directly the cobalt disilicide in regions overlying the exposed silicon portions of the patterned wafer; however, differential etching of the cobalt metal is then more difficult, so that the direct initial formation of cobalt disilicide is better used in cases where a photoresist "lift-off" method is used, that is, in cases where the then exposed complementary portion of the patterned wafer is essentially metallic cobalt underlain by photoresist to be lifted off together with the overlying cobalt.
The second heat treatment, in the oxidizing ambient, produces a thin layer (about 50 to 100 Angstroms) of silicon dioxide on the surface of the cobalt disilicide, the silicon in this layer of silicon dioxide having diffused thereto from the underlying polysilicon layer. As an alternative to this second heat treatment in the oxidizing ambient, a silicon dioxide layer can be deposited on the cobalt silicide layer, as by chemical vapor deposition, either before or after (preferably after, especially in case of gate electrode formation) a heat treatment at 700° C. or more to convert the cobalt silicide into cobalt disilicide.
The technique of forming the relatively stable cobalt disilicide electrodes in accordance with the invention may be used to form such electrodes in other electronic device contexts; and the cobalt disilicide electrodes of the invention can be used solely for the gate electrode in conjunction with other electrodes for source and drain contacts, or vice versa, and also in conjunction with other techniques for electrical isolation of gate, source, and drain, as well as in conjunction with other techniques then silicon nitride (CVD or plasma deposited) for sealing the device structure. Finally, various annealing steps can be added, typically at temperatures in the range of about 450° C. to 950° C., for example, between the above processing steps of cobalt disilicide formation and aluminum metallization.
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In order to form MOSFET structures, a cobalt layer (16) is deposited and sintered, at about 400° C. to 500° C., on a patterned semiconductor wafer having exposed polycrystalline (14) or monocrystalline (11) silicon portions, as well as exposed oxide (15 or 25) portions. The cobalt reacts with exposed surfaces of the silicon portions and forms thereat such compounds as cobalt monosilicide (CoSi) or di-cobalt silicide (C0 2 Si), or a mixture of both. The unreacted cobalt is selectively removed, as by selective etching in a suitable acid bath. A heat treatment at about 700° C. or more, preferably in an oxidizing ambient which contains typically about 2 percent oxygen, converts the cobalt compound(s) into relatively stable cobalt disilicide (CoSi 2 ). Subsequently, deposition of an in situ doped layer (33) of polycrystalline silicon (polysilicon) on the cobalt disilicide contacting the monocrystalline silicon portions--followed by gettering, deposition of a layer (34) of aluminum, and standard etch-patterning of the aluminum and polysilicon layers--completes the metallization of the desired MOSFET structures on the silicon wafer.
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CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional Patent Application 61/104,784 filed by the inventors herein on Oct. 13, 2008, the disclosure of which is incorporated herein by reference.
BACKGROUND
[0002] The present invention relates to the structural organization of MOSFET pairs and, more particularly, to MOSFET pairs having reduced PCB mounting area requirements, increased thermal efficiency, and reduced parasitic impedances.
[0003] Multi-die packaging is common in power converters in which MOSFET switching transistors are used; for example and as shown in FIGS. 1 and 1A , a circuit assembly or package 10 includes a first FET 12 and a second FET 14 in a side-by-side or lateral mounting arrangement on a common plane with a controller or driver chip 16 that is connected via bonding wires 18 between conductive pads (unnumbered) on the driver chip 16 and to contacts 20 of the respective leadframe portions and by bonding wires 18 connected to various contact pads (unnumbered) on the FET structures. A first strap or clip 22 , typically formed from shape-sustaining copper or a copper alloy in ribbon or ribbon-like form, is in electrical and thermal contact with the upper surface of the FET 14 and a second clip 24 is in electrical and thermal contact with the upper surface of the FET 12 . As shown in FIG. 1A , the first clip 24 is generally “L-shaped” and includes a columnar portion (unnumbered) that is in contact with a contact pad 26 of the leadframe; the clip 24 is similarly shaped and is in contact with another portion (unnumbered) of the leadframe. In typical power converter operations, the clips 22 and 24 serve as substantial current carrying conductors as well as heat sinks. While not specifically shown, the various parts are electrically connecting using solder-bonding techniques. As shown in FIG. 1A at 28 , the structure of FIG. 1 is typically encapsulated in a thermosetting molding compound to define a circuit package.
[0004] The MOSFET package shown in FIGS. 1 and 1A finds use in power switching applications including use in synchronous buck converter circuits of the type shown in FIGS. 1B and 1C . In FIG. 1B , two n-channel MOSFETs, FET high and FET low , are in series circuit between V in and ground GND with a switching or phase node PN defined between the source S of FET high and the drain D of FET low . The drain D of FET high is connected to V in while the source S of FET low is connected to ground. The two FETs are alternatively turned on and off by respective on/off pulses of appropriate pulse width and timing from a driver circuit 16 to their gates G to step-down V in into an inductor I. The circuit of FIG. 1C is similar to that of FIG. 1B except that the high-side FET is a p-channel MOSFET with its drain D connected to the drain D of FET low to define the phase node PN; in FIG. 1C , the FET high and FET low are alternatively turned on and off by respective pulses of appropriate pulse width and timing to their gates G from a driver circuit 16 to switch V in into an inductor I. The inductor I can take the form of a planar spiral inductor formed on a substrate or a discrete inductor package. While not specifically shown, the side of the inductor I opposite to that connected to the phase node PN can be connected to one or more capacitors (and/or inductors) to smooth or otherwise condition the output.
[0005] The physical organization of FIG. 1 functions for its intended purpose; however, the side-by-side organization of FIG. 1 militates against more compact circuit packages occupying smaller circuit board areas.
SUMMARY
[0006] A MOSFET pair suited for use in a synchronous buck converter places the FET dies in a stacked relationship to reduce the surface area ‘footprint’; depending upon the electrical circuit used, the source and drain of the two FETs or the drains of the two FETs are connected together, either directly or through an intermediate conductive ribbon, strap, or clip, to establish a common phase or switch node. The stacked organization allows for lower-cost packaging that results in a significant reduction in the surface area footprint of the device and reduces parasitic impedance relative to prior side-by-side organizations while allowing for improved heat sinking.
BRIEF DESCRIPTION OF THE DRAWING
[0007] FIG. 1 is a plan view of a representative or example multi-die assembly in which two MOSFET structures are mounted adjacent one another in a common plane;
[0008] FIG. 1A is a cross-sectional view of the structure of FIG. 1 taken along line 1 A- 1 A of FIG. 1 ;
[0009] FIG. 1B is a simple circuit diagram of two n-channel enhancement-mode MOSFETs in a synchronous buck-convertor configuration;
[0010] FIG. 1C is a simple circuit diagram of an n-channel and a p-channel enhancement-mode MOSFET in a synchronous buck-convertor configuration;
[0011] FIGS. 2A and 2B are an example of a first stacked FET organization;
[0012] FIG. 2C is an simple circuit diagram representing the physical organization of FIGS. 2A and 2B ;
[0013] FIGS. 3A and 3B represent a variation of the stacked FET organization of FIGS. 2A and 2B ;
[0014] FIG. 4 is another example a stacked FET organization;
[0015] FIG. 5A is further example a stacked FET organization;
[0016] FIG. 5B is a variation of the stacked FET organization of FIG. 5A ;
[0017] FIG. 5C is representative physical representation of the organization of FIG. 5B ; and
[0018] FIG. 6 is further example a stacked FET organization.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] FIG. 2A is an idealized symbolic representation of a first MOSFET organization in which NMOS FETs are used for both the high side FET and the low side FET, and FIG. 2B is a representative pictorial representation of one possible embodiment of the representation of FIG. 2A with the corresponding electrical circuit shown in FIG. 2C . In both FIGS. 2A and 2B , the two FETs are shown in symbolic or idealized fashion as right parallelepipeds each having major surface-area upper and lower surfaces with the smaller-volume parallelepiped mounted on top of or stacked upon the larger-volume parallelepiped; in practice, actual FET structures are somewhat differently shaped and have different sizing and thicknesses from that illustrated depending upon the manufacturing process and design constraints. The FETs shown are vertical FETs and can be characterized as having an upper or top region or surface (which can constitutes a source or drain contact), a lower or bottom region or surface (which can constitute a drain or a source contact), and an intermediate region therebetween through which a controllable current can flow as a function of gate control signals applied to a gate electrode.
[0020] In FIG. 2A , a high side FET high includes source S, drain D, and gate G contacts and is mounted in a bottom drain/top source orientation on an underlying die pad (not shown in FIG. 2A ) connected to a V in trace on the underlying printed circuit board; the die pad is typically part of a larger leadframe. The low side FET low is also in a bottom drain/top source orientation with the drain D of the low side FET low mounted upon and electrically connected or bonded (i.e., solder bonded) to the source S surface of high side FET high to define the phase node PN therebetween. The phase node PN is then connected to an inductor I using a shape-sustaining clip (generally indicated as PNC), conductive ribbon, or strap. As is also known, the connection to the phase node can be implemented by a plurality of bonding wires (not shown). The source S of low side FET low is wire bonded or otherwise connected to a ground trace on the PCB. The gates G of the high side FET high and the low side FET low are wire bonded to their respective driver (not shown in FIG. 2A of which the driver 16 of FIG. 1 is suitable) to allow the high side FET high and the low side FET low to be alternately turned on and off by appropriately timed and spaced pulses to the gates G of both the high side FET high and the low side FET low . In FIG. 2A , the high side FET high is larger than the low side FET low as is the case where the ratio of V out /V in is >0.5.
[0021] FIG. 2B is representative of one possible physical or package organization of the arrangement of FIG. 2A using conductive clips; as shown, the bottom-drain high side FET high is mounted upon and electrically connected or bonded to a die pad 100 of an underlying substrate SS (shown generically in dotted-line), which can take the form of leadframe (not fully shown), a substrate pad (not shown), or an underlying printed circuit board (not shown) to connect the drain D to a V in trace or other V in source. The drain D of the low side FET low is mounted upon and electrically connected or bonded to the source S surface of high side FET high to define the phase node PN therebetween. An L-shaped conductive clip PNC is in electrical contact with or electrically bonded to the phase node PN via an electrical connection to the source S surface of high side FET high and has an columnar portion in contact with another contact pad 102 of the underlying leadframe (or other suitable substrate). In this organization, the contact pad 102 is then connected to an inductor I, which can take the form of a planar inductor or a discrete inductor mounted on the printed circuit board (not specifically shown). Another L-shaped conductive clip GC is in contact with the source S of low side FET low and has a columnar portion in contact with another contact pad 104 of the underlying leadframe (or printed circuit board) which, in turn, is connected to circuit ground GND. The gates G of the high side FET high and the low side FET low are wire bonded to their respective driver (not shown in FIG. 2B of which the driver 16 of FIG. 1 is an example) to allow the high side FET high and the low side FET low to be alternately turned on and off by pulses of appropriate pulse width and timing applied to their respective gates G. While not specifically shown, those surfaces of the FETs that are electrically connected to other components can be solder-bonded using solder paste/reflow techniques.
[0022] FIG. 2C illustrates the equivalent electrical circuit for the physical organization of FIGS. 2A and 2B showing the drain D of the side FET low and the source S of the high side FET high connected to the inductor I via the phase node PN with the source S of the low side FET low connected to ground GND and the drain D of the high side FET high connected to V in . The driver circuit 16 provides a succession of alternating on/off pulses of appropriate pulse width and timing to the gates G of FET high and FET low to turn the FETs on and off. The inductor I can take the form of a substantially planar spiral conductive path formed an a substrate or a discrete inductor device. While not specifically shown, the side of the inductor I opposite to that connected to the phase node PN can be connected to one or more capacitors and/or inductors to smooth or otherwise condition the output.
[0023] FIGS. 3A and 3B represent a variation of the arrangement and organization of FIGS. 2A and 2B and shows the conductive clip PNC fully interposed between and electrically connected or bonded to the drain D of the low side FET low and the source S of the high side FET high . The FIG. 3A arrangement maximizes the electrical contact area and the heat transfer area at the phase node PN between the drain D of the low side FET low and the source S of the high side FET high to maximize heat sinking, as indicated symbolically at Q. While a fully interposed conductive clip PNC is preferred, other arrangements in which the conductive clip PNC does not fully extend between the surface of the FETs is also acceptable.
[0024] FIG. 4 illustrates an embodiment better suited for use where the ratio of V out /V in is <0.5 where the low side FET low is normally volumetrically larger than the high side FET high ; the physical organization of FIG. 4 is electrically the same as that of FIGS. 2A-2C . In FIG. 4 , the high side FET high is arranged in a bottom drain/top source organization and formed as a strip-like parallelepiped having a source S and drain D with a gate G shown to the left. The larger volume, bottom drain/top source low side FET low is positioned above the high side FET high with a conductive clip PNC (fabricated from a shape-sustaining copper or copper-alloy material) interposed between and electrically connected to or electrically bonded to the source S of the high side FET high and the drain D of low side FET low with the conductive clip PNC extending across the surface of the low side FET low that defines the drain D to connect to the inductor I. The conductive clip PNC can be also be shaped as an L-shaped component in a manner consistent with FIG. 3B .
[0025] FIG. 5A represents a physical organization similar to that of FIGS. 2A and 3A but in which a bottom drain/top source p-channel MOSFET functions as the high side FET high and a bottom source/top drain n-channel MOSFET functions as the low side FET low in a manner electrically consistent with FIG. 1C .
[0026] As shown in FIG. 5A , the source S of the low side FET low connects to ground with its gate G isolated therefrom. The drain D of the low side FET low electrically connects to the drain D of the high side FET high to define the phase node PN therebetween. The source S of the high side FET high is connected to V in with a phase node connector PNC electrically connected or bonded to the drain D of the low side FET low to connect the phase node PN to the inductor I. As in the case of the FIG. 2A embodiment, the gates G of the high side FET high and the low side FET low are wire bonded to their respective drivers (not shown) to allow the high side FET high and the low side FET low to be alternately turned on and off by pulses of appropriate duration and timing applied to their respective gates. In the embodiment of FIG. 5B , the phase node connector PNC is interposed between and electrically connected or bonded to the drain D of the low side FET low and the drain D of the high side FET high .
[0027] The arrangements of FIGS. 5A and 5B can be configured, as one possible physical organization, in a manner consistent with that of FIGS. 2B and 3B . For example and as shown in FIG. 5C , the low side FET low is mounted upon a contact pad 100 of an underlying leadframe (not fully shown), a substrate (not shown), or an underlying printed circuit board (not shown) with its source S connected a ground trace. An L-shaped conductive clip PNC is positioned intermediate the drain D of the low side FET low and the drain D of the high side FET high to define the phase node PN. The conductive clip PNC has a columnar portion in contact with another contact pad 102 of the underlying leadframe (or printed circuit board). In this organization, the contact pad 102 is then connected to an inductor I, which can take the form of a planar inductor or a discrete inductor mounted on the printed circuit board (not specifically shown). Another L-shaped conductive clip V in C is in contact with the source S of high side FET high and has an columnar portion in contact with another contact pad 104 of the underlying leadframe (or printed circuit board) which is in contact with a V in source. The gates G of the high side FET high is wire bonded to its respective driver contact (not shown in FIG. 5C of which the driver 16 of FIG. 1 is an example). In FIG. 5C , the gate of the low side FET low is not shown and is located on the underside of the FET low facing the contact pad 100 ; in this case, an appropriately sized opening (not shown) is formed in the contact pad 100 to allow access the gate G of the low side FET low . In FIG. 5C , the conductive clip PNC is fully interposed between the FET high and the FET low ; if desired a conductive clip of the type shown in FIG. 2B can also be used.
[0028] FIG. 6 illustrates an embodiment well suited for use where the ratio of V out /V in is >0.5 where the low side FET low is normally volumetrically smaller than the high side FET high ; the physical organization of FIG. 6 is electrically the same at that of FIG. 1C , described above. In FIG. 6 , the low side FET low is formed as a strip-like parallelepiped having a source S and drain D with a gate G shown to the left. The larger volume high side FET high is positioned above the low side FET low with a conductive clip PNC (fabricated from a shape-sustaining copper or copper-alloy material) interposed between the drain D of the high side FET high and the drain D of low side FET low with the conductive clip PNC extending across the surface of the high side FET high that defines the drain D to connect to the inductor I.
[0029] The stacked organization described herein allows for lower-cost packaging that results in a significant reduction in the surface area footprint of the device and reduces parasitic impedance relative to the prior side-by-side organization and allows for improved heat sinking.
[0030] As will be apparent to those skilled in the art, various changes and modifications may be made to the illustrated embodiment of the present invention without departing from the spirit and scope of the invention as determined in the appended claims and their legal equivalent.
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An improved organization for a MOSFET pair mounts first and second FET dies in an overlying or stacked relationship to reduce the surface area ‘footprint’ of the MOSFET pair. The source and drain of a high side FET high and a low side FET low or the drains of the respective high side FET high and low side FET low are bonded together, either directly or through an intermediate conductive ribbon or clip, to establish a common source/drain or drain/drain node that functions as the switch or phase node of the device. The stacked organization allows for lower-cost packaging that results in a significant reduction in the surface area footprint of the device and reduces parasitic impedance relative to the prior side-by-side organization and allows for improved heat sinking.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority from U.S. Provisional Application No. 60/650,226, filed Feb. 3, 2005, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The invention relates to delivery of interferon at controlled rates over extended periods of time.
Interferons are a group of glycoprotein cytokines produced by cells in response to various stimuli, such as exposure to virus, bacterium, parasite, or other antigen. Interferons have antiviral, immunomodulatory, and antiproliferative activities. Interferons are classified as Type I or Type II. Interferons classified as Type I bind to a common receptor called the Interferon Type I or α-β receptor and are produced by leukocytes, fibroblasts, or lymphoblasts in response to virus or interferon inducers. Interferon Type I includes interferon alpha (IFN-α), interferon beta (IFN-β), and interferon omega (IFN-ω), but IFN-ω has limited homology to human IFN-α (about 60%) and human IFN-β (about 29%). Interferons classified as Type II are produced by T-lymphocytes. Interferon Type II includes interferon gamma (IFN-γ). Interferons are used for treatment of viral hepatitis, multiple sclerosis, and certain cancers. IFN-ω in particular has been indicated for treatment of Hepatitis B & C populations. The injectable form of IFN-ω is currently in Phase II clinical studies for Hepatitis C. This injectable form is solution-based and is not formulated for sustained delivery.
There is interest in delivering interferons to patients in a controlled manner over a prolonged period without intervention. For instance, sustained delivery of IFN-ω can improve the therapeutic effect of IFN-ω by reduction or elimination of peak plasma-level related effects of multiple bolus injections, thereby potentially minimizing systemic side effects such as fatigue and flu-like symptoms. Sustained delivery of a beneficial agent without intervention can be provided by implantable drug delivery devices, e.g., osmotic, mechanical, or electromechanical pump implants, and depot injections. Implantable drug delivery devices are attractive for a number of reasons. For example, implantable drug delivery devices can be designed to provide therapeutic doses of the drug over periods of weeks, months, or even a year. Depot injections typically provide therapeutic doses over periods of weeks. Implantable drug delivery devices once inserted in the patient are not easily tampered with by the patient. Thus, patient compliance is generally assured.
Sustained delivery of an interferon requires the interferon to be contained within a formulation that is substantially stable at elevated temperature, e.g., 37° C. or higher, over the operational life of the implantable delivery drug device. Interferon is a biomolecular material, specifically a protein. Generally speaking, protein formulations that are stable at elevated temperature for a long duration, e.g., weeks, months, or a year, are difficult to design. Proteins are naturally active in aqueous environments. Therefore, it would be convenient to formulate proteins as aqueous solutions. Unfortunately, proteins are typically only marginally stable in aqueous formulations for a long duration. One reason for this is that proteins can degrade via a number of mechanisms, such as deamidation (usually by hydrolysis), oxidation, disulfide interchange, and racemization, and water is a reactant in many of these degradation pathways. Water also acts as a plasticizer and facilitates denaturation and/or aggregation of protein molecules.
Aqueous protein formulations may be reduced to particles using techniques such as freeze-drying or lyophilization, spray-drying, and desiccation. Such particle protein formulations may exhibit increased stability over time at ambient and even elevated temperature. However, there is the challenge of delivering particle formulations from an implantable drug delivery device at a controlled flow rate. It has been suggested to suspend particle protein formulations in non-aqueous, flowable vehicles to allow their delivery from an implantable drug delivery device. A suitable vehicle typically has a high viscosity, e.g., 1 kP or more, so that the particles can be uniformly dispersed in the suspension for a desired duration.
From the foregoing, there continues to be a need for a formulation of interferon that is stable at storage and delivery conditions for a desired duration and deliverable via an implantable drug delivery device.
SUMMARY OF THE INVENTION
In one aspect, the invention relates to a suspension formulation of interferon which comprises a non-aqueous, single-phase vehicle including at least one polymer and at least one solvent, the vehicle exhibiting viscous fluid characteristics, and an interferon contained in a particle formulation dispersed in the vehicle. The particle formulation includes a stabilizing component comprising one or more stabilizers selected from the group consisting of carbohydrates, antioxidants, and amino acids. The suspension formulation is characterized in that less than 10% of the interferon degrades over 3 months under an accelerated storage condition.
In another aspect, the invention relates to a method of treating an interferon-responsive disorder which comprises administering to a subject the suspension formulation described above.
Other features and advantages of the invention will be apparent from the following description.
BRIEF DESCRIPTION OF DRAWINGS
So that the above recited features and advantages of the invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
FIG. 1 shows a scanning electron microscope (SEM) image of spray dried particles.
FIG. 2 shows particle size distribution for four different spray dry runs from spray solutions of particle formulations.
FIG. 3 shows percentage of main peak of IFN-ω as measured by Reversed Phase High Performance Liquid Chromatography (RP-HPLC) for particle formulations of IFN-ω before and after spray drying.
FIG. 4 shows main peak as measured by RP-HPLC for IFN-ω particle formulation suspended in LA/PVP vehicle.
FIG. 5 shows monomer and purity levels at various time points for IFN-ω particle formulation suspended in CERAPHYL® 31/PVP vehicle.
FIG. 6 shows stability results for IFN-ω particle formulation suspended in CERAPHYL® 31/PVP vehicle.
FIG. 7 shows stability results for IFN-ω particle formulation suspended in BB/PVP vehicle.
FIG. 8A shows stability of IFN-ω in LL/PVP vehicle after 6-month storage at 40° C.
FIG. 8B shows stability of IFN-ω against degradation in LL/PVP vehicle after 6-month storage at 40° C.
FIG. 8C shows protein content stability in LL/PVP vehicle after 6-month storage at 40° C.
FIG. 9 shows release rate for IFN-ω particle formulation suspended in LA/PVP from osmotic pumps.
FIG. 10 shows release rate for IFN-ω particle formulation suspended in LL/PVP from osmotic pumps.
FIG. 11 shows release rate for IFN-ω particle formulation suspended in BB/PVP from osmotic pumps.
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described in detail with reference to a few preferred embodiments, as illustrated in accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the invention may be practiced without some or all of these specific details. In other instances, well-known features and/or process steps have not been described in detail in order to not unnecessarily obscure the invention. The features and advantages of the invention may be better understood with reference to the drawings and discussions that follow.
The invention provides particle formulations of interferon that can be used to prepare suspension formulations of interferon that are deliverable via sustained delivery systems, e.g., implantable drug delivery devices and depot injections. Interferons that may be included in particle formulations of the invention may be recombinant molecules that can activate the Interferon Type I receptor (α-β receptor) or Interferon Type II receptor. These recombinant molecules may or may not contain sequence homology to native human Type I or Type II interferons. Interferons according to embodiments of the invention may be selected from the group consisting of proteins having the biological activity of recombinant human interferon, interferon analogs, interferon isoforms, interferon mimetics, interferon fragments, hybrid interferon proteins, fusion protein oligomers and multimers of the above, homologues of the above, glycosylation pattern variants of the above, muteins of the above, and interferon molecules containing the minor modifications enumerated above. Interferons according to the invention shall not be limited by method of synthesis or manufacture and shall include those synthesized or manufactured by recombinant (whether produced from cDNA or genomic DNA), synthetic, transgenic, and gene-activated methods. Specific examples of interferons include, but are not limited to, IFN-α, IFN-β, IFN-ω, and IFN-γ.
Particle formulations of the invention are preferably chemically and physically stable for at least 1 month, more preferably at least 3 months, most preferably at least 6 months, at delivery temperature. The delivery temperature could be normal body temperature, e.g., 37° C., or slightly higher than normal body temperature, e.g., 40° C. Particle formulations of the invention are preferably chemically and physically stable for at least 3 months, more preferably at least 6 months, most preferably at least 12 months, at storage temperature. The storage temperature could be refrigeration temperature, e.g., around 5° C., or room temperature, e.g., around 25° C. The term “chemically stable” means that an acceptable percentage of degradation products produced by chemical pathways such as deamidation (usually by hydrolysis) or oxidation is formed. For example, a formulation may be considered chemically stable if less than 35%, preferably no more than about 20%, breakdown products are formed after 3 months, preferably after 6 months, at delivery temperature and after 6 months, preferably after 12 months, at storage temperature. The term “physically stable” means that an acceptable percentage of aggregates (e.g., dimers and other higher molecular weight products) is formed. For example, a formulation may be considered physically stable if less than 10%, preferably no more than 3%, more preferably less than 1%, aggregates are formed after 3 months, preferably after 6 months, at delivery temperature and 6 months, preferably 12 months, at storage temperature.
Preferably, particle formulations of the invention are formable into particles using processes such as spray drying, lyophilization, desiccation, freeze-drying, milling, granulation, ultrasonic drop creation, crystallization, and precipitation. Preferably, the particles are uniform in shape and size to ensure consistent and uniform rate of release from the delivery device. Preferably, the particles are sized such that they can be delivered via an implantable drug delivery device. For example, in a typical osmotic pump implant having a delivery orifice, the size of the particles should be no greater than 30%, preferably no greater than 20%, more preferably no greater than 10%, of the diameter of the delivery orifice. It is also desirable that the particles when incorporated in a suspension vehicle do not settle within 3 months at delivery temperature. Generally speaking, smaller particles tend to have a lower settling rate in viscous suspension vehicles than larger particles. Therefore, micron- to nano-sized particles are typically desirable. For an osmotic pump implant having a delivery orifice diameter in a range from 0.1 to 0.5 mm, for example, particle sizes are preferably less than 50 μm, more preferably less than 10 μm, most preferably in a range from 3 to 7 μm.
The invention provides particle formulations of interferons possessing many or all of the characteristics described above. For example, particle formulations according to embodiments of the invention are chemically and physically stable at 40° C. for at least 6 months and at 5° C. and 25° C. for at least 12 months. We have found that particle formulations according to embodiments of the invention can be prepared by spray drying with high yield, e.g., greater than 50%, with average particle size typically less than 50 μm and moisture content typically below 5% by weight. Particle formulations according to embodiments of the invention may also be prepared by other suitable processes available in the art for forming particles from a mixture of components, such as lyophilization, freeze-drying, milling, granulation, ultrasonic drop creation, crystallization, precipitation, and dessication. Particle formulations according to embodiments of the invention preferably have a low moisture content, typically less than 5% by weight.
In one embodiment, a particle formulation includes an interferon as described above, one or more stabilizers, and optionally a buffer. The stabilizers may be carbohydrate, antioxidant and/or amino acid. The amounts of stabilizers and buffer in the particle formulation can be determined experimentally based on the activities of the stabilizers and buffers and the desired characteristics of the formulation. Carbohydrate, antioxidant, amino acid, and buffer levels are generally all of concern in creating a particle formulation according to the invention. Typically, the amount of carbohydrate in the formulation is determined by aggregation concerns. In general, the carbohydrate level should not be too high so as to avoid promoting crystal growth in the presence of water due to excess carbohydrate unbound to interferon. Typically, the amount of antioxidant in the formulation is determined by oxidation concerns, while the amount of amino acid in the formulation is determined by oxidation concerns and/or formability of particles during spray drying. Typically, the amount of buffer in the formulation is determined by pre-processing concerns, stability concerns, and formability of particles during spray drying. Buffer may be required to stabilize interferon during processing, e.g., solution preparation and spray drying, when all excipients are solubilized. However, care should be exercised in determining the amount of buffer. Too much buffer can produce a buffer system in the presence of water, which can then lead to crystallization.
Examples of carbohydrates that may be included in the particle formulation include, but are not limited to, monosaccharides, such as fructose, maltose, galactose, glucose, D-mannose, and sorbose, disaccharides, such as lactose, sucrose, trehalose, cellobiose, polysaccharides, such as raffinose, melezitose, maltodextrins, dextrans, and starches, and alditols (acyclic polyols), such as mannitol, xylitol, maltitol, lactitol, xylitol sorbitol, pyranosyl sorbitol, and myoinsitol. Preferred carbohydrates include non-reducing sugars, such as sucrose, trehalose, mannitol, and dextrans.
Examples of antioxidants that may be included in the particle formulation include, but are not limited to, methionine, ascorbic acid, sodium thiosulfate, catalase, platinum, ethylenediaminetetraacetic acid (EDTA), citric acid, cysteins, thioglycerol, thioglycolic acid, thiosorbitol, butylated hydroxanisol, butylated hydroxyltoluene, and propyl gallate.
Examples of amino acids that may be included in the particle formulation include, but are not limited to, arginine, methionine, glycine, histidine, alanine, L-leucine, glutamic acid, Iso-leucine, L-threonine, 2-phenylamine, valine, norvaline, praline, phenylalanine, trytophan, serine, asparagines, cysteine, tyrosine, lysine, and norleucine. Preferred amino acids include those that readily oxidize, e.g., cysteine, methionine, and trytophan.
Examples of buffers that may be included in the particle formulation include, but are not limited to, citrate, histidine, succinate, phosphate, maleate, tris, acetate, carbohydrate, and gly-gly. Preferred buffers include citrate, histidine, succinate, and tris.
The particle formulation may include other excipients, such as surfactants, bulking agents, and salts. Examples of surfactants include, but are not limited to, Polysorbate 20, Polysorbate 80, PLURONIC® F68, and sodium docecyl sulfate (SDS). Examples of bulking agents include, but are not limited to, mannitol and glycine. Examples of salts include, but are not limited to, sodium chloride, calcium chloride, and magnesium chloride.
Table 1 below shows examples of particle formulation composition ranges of the invention.
TABLE 1
MOST
PREFERRED
PREFERRED
RANGE
RANGE
RANGE
LOADING IN PARTICLE FORMULATION (WT %)
Protein
0.1 to 99.9%
1 to 50%
1 to 35%
Surfactant
0.0 to 10%
0.01 to 10%
0.01 to 5%
Bulking Agent
0 to 99.9%
0 to 70%
Salt
0 to 99.9%
0 to 70%
STABILIZERS TO PROTEIN (WT RATIO)
Carbohydrate
0.1 to 99.9
>0.5
>1
Antioxidant and/or
0 to 99.9
>0.5
amino acid
BUFFER
Buffer to Protein
0-3
1.5-2.5
1.7-2.2
(WT RATIO)
Concentration
5 mM to
5 mM to 25 mM
15 mM to 25 mM
50 mM
pH
5.0 to 8.0
5.5 to 6.5
One particularly useful example of particle interferon formulations includes 1:2:1:1.5-2.5 interferon:carbohydrate:antioxidant and/or amino acid:buffer. The term “antioxidant and/or amino acid” refers to antioxidant alone or amino acid alone or a combination of antioxidant and amino acid. In another example, particle interferon of formulations 1:2:1:1.5-2.5 IFN-ω:sucrose:methionine:citrate were prepared.
As stated earlier, particle formulations of the invention may be prepared by known techniques such as spray drying, lyophilization, desiccation, or other technique available in the art for forming particles from a mixture of components. A typical spray dry process may include loading a spray solution containing a protein and stabilizing excipients into a sample chamber, which may be maintained at refrigeration to room temperature. Refrigeration generally promotes stability of the protein. A feed pump then sprays the spray solution into a nozzle atomizer. At the same time, atomized gas (typically, air, nitrogen, or inert gas) is directed at the outlet of the nozzle atomizer to form a mist of droplets from the spray solution. The mist of droplets are immediately brought into contact with a drying gas in a drying chamber. The drying gas removes solvent from the droplets and carries the particles into a collection chamber. In spray drying, factors that can affect yield include, but are not limited to, localized charges on particles, which could promote adhesion of the particles to the spray dryer, and aerodynamics of the particles, which could make it difficult to collect the particles. In general, yield of the spray dry process depends in part on the particle formulation. As will be demonstrated below, particle formulations of the invention can be effectively spray dried.
In one embodiment, spray dried particles were formed from spray solutions containing IFN-ω, sucrose (carbohydrate), methionine (amino acid), and citrate (buffer). In a preferred embodiment, IFN-ω, sucrose, methionine, and citrate are present in the solution in a ratio of 1:2:1:1.5-2.5 (IFN-ω:sucrose:methionine:citrate). FIG. 1 shows a SEM image for spray dried particles formed from a spray solution having IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15. The average particle size is 4-5 μm. The particles have buckled or raisin-like morphology. FIG. 2 shows particle size distributions of four different spray dry runs for a spray solution having IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15. FIG. 2 shows that IFN-ω formulations of the invention can be reproducibly spray dried with tight particle size distribution profiles.
Table 2 shows yield data for various spray-dried formulations of the invention. The results show that yield greater than 60% is achievable with IFN-ω particle formulations of the invention. In Table 2, “batch size” is starting solid material (g) in spray dry solution and “yield” is percent solid material captured after spray drying.
TABLE 2
IFN-ω
Sucrose
Methionine
Citrate
Batch Size
Yield
A
1
2
1
1.7
16.1 g
77.2%
B
1
2
1
2.2
2.4 g
60.6%
The following examples further illustrate the invention. These examples are not intended to limit the invention as otherwise described herein.
In the examples below, stability samples were evaluated before and after spray drying using Reversed Phase High Performance Liquid Chromatography (RP-HPLC). RP-HPLC is used to monitor IFN-ω chemical stability. The main IFN-ω chemical degradation products (oxidized and deamidated forms) were separated from the native form using a reversed phase Zorbax 300SB-C8 column maintained at 55° C. Protein peaks were monitored by UV at 220 nm. The mobile phase involves a gradient elution, with solvent A: 0.1% trifluoroacetic acid in water, and solvent B: 0.08% trifluoroacetic acid in acetonitrile, and is pumped at the flow rate of 1.2 mL/min. For comparison purposes, stability samples were also evaluated for monomers using Size Exclusive Chromatography (SEC).
The stability samples were evaluated under long term storage and accelerated storage conditions. According to the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use Q1A(R2) guideline, long term stability condition is 25° C.±2° C./60% RH±5% RH for 12 months for the general case and 5° C.±3° C. for 12 months for drug substances intended for storage in a refrigerator. The accelerated storage condition is 40° C.±2° C./75% RH±5% RH for the general case and 25° C.±2° C./60% RH±5% RH for 6 months for drug substances intended for storage in a refrigerator.
It is desirable that particle IFN-ω formulations according to embodiments of the invention have oxidation level less than 7%, deamidation level less than 7%, and dimer level less than 3% after 3 months at accelerated storage condition (e.g., 40° C.±2° C./75% RH±5% RH) or 6 months at long term storage condition (e.g., 25° C.±2° C./60% RH±5% RH). These preferable oxidation and deamidation upper limits are based on impurity levels associated with the highest dosage of IFN-ω injected during Phase I and/or II clinical trials. The desired dimer upper limit is based on acceptable dimer levels associated with other proteins. The total aggregation after 6 months of accelerated storage is preferably less than 10%, more preferably less than 8%, most preferably less than 5%.
Example 1
A bulk solution of IFN-ω was obtained as a frozen solution having a concentration of approximately 5 mg/ml. The IFN-ω solution was dialyzed against 25 mM citrate solution (pH 6.0). Sucrose and methionine in citrate solution were added to the dialyzed IFN-ω to make final IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:1.77. The solution was spray dried as described above. The average particle size was 4-5 μm. The spray solution and spray dried particles were analyzed using RP-HPLC. The first two bars of FIG. 3 show percent main peak for the spray solution and spray dried particles of this example. Percent main peak refers to the fraction of IFN-ω detected that is in a monomeric form and does not appear to be chemically degraded in any form
Example 2
A bulk solution of IFN-ω was obtained as a frozen solution having a concentration of approximately 5 mg/ml. The IFN-ω solution was dialyzed against 25 mM citrate solution (pH 6.0). Sucrose and methionine in citrate solution were added to the dialyzed IFN-ω to make final IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15. The solution was spray dried as described above. The average particle size was 4-5 μm. The spray solution and spray dried particles were analyzed using RP-HPLC. The second two bars of FIG. 3 show percent main peak for the spray solution and spray dried particles of this example.
Example 3
A bulk solution of IFN-ω was obtained as a frozen solution having a concentration of approximately 5 mg/ml. The IFN-ω solution was dialyzed against 25 mM citrate solution (pH 6.0). Sucrose and methionine in citrate solution were added to the dialyzed IFN-ω to make final IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.2 at IFN-ω concentration of 3.3 mg/mL. The solution was spray dried as described above. The spray dried particles were evaluated using RP-HPLC and SEC at various timepoints during storage. The results are shown in Tables 3 and 4 below.
TABLE 3
RP-HPLC
Protein
SEC Monomer
Main Peak
Content
Temperature
(Standard
(Standard
(Standard
(° C.)
Time (months)
Deviation)
Deviation)
Deviation)
A (n = 15)
0
100.00 (0.01)
96.26 (0.39)
16.11 (0.21)
B (n = 3)
40
1
99.85 (0.00)
96.99 (0.19)
16.47 (0.07)
C (n = 3)
40
2
99.90 (0.01)
95.85 (0.01)
16.16 (0.22)
D (n = 3)
40
3
99.93 (0.02)
96.45 (0.35)
16.51 (0.22)
E (n = 3)
40
6
99.88 (0.00)
95.24 (0.12)
17.01 (0.13)
F (n = 3)
25
6
99.93 (0.01)
96.20 (0.10)
17.14 (0.14)
G (n = 3)
25
12
99.93 (0.01)
96.15 (0.12)
17.46 (0.14)
H (n = 3)
5
6
99.93 (0.02)
96.03 (0.11)
16.92 (0.05)
I (n = 3)
5
12
99.96 (0.01)
96.15 (0.03)
17.50 (0.11)
TABLE 4
Dimers %
Oxidation %
Deamidation
Temperature
Time
(Standard
(Standard
(Standard
Total
(° C.)
(months)
Deviation)
deviation)
deviation)
aggregation
A (n = 15)
0
0.00 (0.00)
2.20 (0.11)
1.53 (0.46)
3.73
B (n = 3)
40
1
0.15 (0.00)
1.98 (0.02)
1.03 (0.02)
3.16
C (n = 3)
40
2
0.15 (0.00)
2.60 (0.03)
1.56 (0.03)
4.31
D (n = 3)
40
3
0.07 (0.02)
2.13 (0.16)
1.43 (0.20)
3.63
E (n = 3)
40
6
0.12 (0.00)
2.83 (0.12)
1.93 (0.03)
4.88
F (n = 3)
25
6
0.07 (0.01)
2.71 (0.08)
1.09 (0.02)
3.87
G (n = 3)
25
12
0.07 (0.01)
2.10 (0.11)
1.75 (0.01)
3.92
H (n = 3)
5
6
0.07 (0.02)
2.77 (0.09)
1.20 (0.02)
4.04
I (n = 3)
5
12
0.04 (0.01)
2.19 (0.01)
1.66 (0.02)
3.89
Table 3 shows that monomer and main peak were more than 99.8% and 86.5%, respectively, over the stability temperatures and times studied. Table 3 shows that protein content is relatively stable over time. Table 4 shows that dimer, oxidation, and deamidation levels were less than 0.2%, 2.9%, and 2%, respectively, over the stability temperatures and times studied. For comparison purposes, the bulk IFN-ω initially had approximately 1.5% oxidation level, 1.5% deamidation level, and 0% dimer level. Table 4 also shows that the total aggregation after 6 months of accelerated storage (formulation E) is less than 5%.
Example 4
Lyophilized IFN-ω particle formulations (IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:0, 20 mM citrate, pH 6.0) were analyzed using RP-HPLC at various timepoints under long term and accelerated storage conditions. The results are shown in Table 5. The results show that IFN-ω remained stable even after 24 weeks at long term and accelerated storage conditions.
TABLE 5
RP-HPLC
Main Peak
Temperature
(Standard
(° C.)
Time (weeks)
Deviation)
1
4
0
99.61 (0.04)
2
4
4
99.35 (0.02)
3
4
8
100.00 (0.00)
4
4
12
99.62 (0.02)
5
4
24
99.53 (0.07)
6
40
0
99.61 (0.04)
7
40
2
99.75 (0.43)
8
40
4
99.12 (0.07)
9
40
8
99.04 (0.28)
10
40
12
98.86 (0.07)
11
40
24
98.67 (0.31)
12
65
0
99.61 (0.04)
13
65
2
97.82 (0.17)
14
65
4
96.87 (0.04)
The invention also provides suspension formulations of interferon that are deliverable via sustained release systems, e.g., implantable drug delivery devices and depot injections. The suspension formulations include particle formulations of interferon as described above suspended in vehicles. A vehicle according to an embodiment of the invention includes at least a polymer and a solvent combined together to provide a single-phase material that is biocompatible and non-aqueous. The suspension formulations of the invention are stable at elevated temperature and are deliverable via a sustained release system over a prolonged period.
The polymers and solvents used in vehicles according to embodiments of the invention are chosen to provide a homogeneous system that is both physically and chemically uniform throughout, for example, as determined by differential scanning calorimetry (DSC). To achieve a biocompatible vehicle, the polymers and solvents used in a vehicle according to the invention are chosen and combined such that the resultant vehicle disintegrates or breaks down over a period of time in response to a biological environment. The breakdown of the vehicle in a biological environment may take place by one or more physical or chemical processes, such as by enzymatic action, oxidation, reduction, hydrolysis (e.g., proteolysis), displacement, or dissolution by solubilization, emulsion or micelle formation. After a vehicle of the invention is broken down in a biological environment, components of the vehicle are then absorbed or otherwise dissipated by the body and surrounding tissue.
In one embodiment, the vehicle includes any pharmaceutically-acceptable polymer that can be combined with a pharmaceutically-acceptable solvent to provide a vehicle that is single-phase, biocompatible, suitable for creating and maintaining a suspension of a beneficial agent, and capable of providing a stable formulation of a beneficial agent. The polymer may be biodegradable or non-biodegradable. Preferably, the polymer is somewhat soluble in water. Examples of polymers useful in forming the vehicle include, but are not limited to, pyrrolidones, e.g., polyvinylpyrrolidone (PVP) having a molecular weight of 2,000 to 1,000,000, methylcellulose, carboxy methylcellulose, polylactides, polyglycolides, polylactide-co-glycolide, polylactic acids, polyglycolic acids, polyoxyethylene polyoxypropylene block copolymers (exhibiting a high viscosity at elevated temperatures, e.g., 37° C.) such as PLURONIC® 105, and esters or ethers of unsaturated alcohols such as vinyl acetate. If desired, more than one different polymer or grades of single polymer may be used to achieve a vehicle according to the invention.
In one embodiment, the vehicle includes any pharmaceutically-acceptable solvent that can be combined with a pharmaceutically-acceptable polymer to provide a vehicle that is single-phase, biocompatible, suitable for creating and maintaining a suspension of a beneficial agent, and capable of providing a stable formulation of a beneficial agent. The solvent may or may not be water soluble. Examples of solvents that may be used to provide a vehicle according to the present invention include, but are not limited to, benzyl benzoate (BB), benzyl alcohol (BA), lauryl lactate (LL), CERAPHYL® 31 (C31), lauryl alcohol (LA), polyethylene glycols (PEGs), glycofural (GF), vitamin E, and DMSO. Where desired, two or more solvents may be used to provide a vehicle according to the invention. In particular, two or more solvents may be required to provide a vehicle that facilitates the production of a stable formulation of a chosen beneficial agent.
The amount of polymer(s) and solvent(s) included in a vehicle according to the invention may be varied to provide the vehicle with desired performance characteristics. Generally speaking, a vehicle according to the invention will include about 40% to 80% (w/w) polymer(s) and about 20% to 60% (w/w) solvent(s). Presently preferred embodiments of a vehicle according to the invention include vehicles formed of polymer(s) and solvent(s) combined at the following ratios: about 25% solvent and about 75% polymer; about 30% solvent and about 70% polymer; about 35% solvent and about 65% polymer; about 40% solvent and about 60% polymer; about 45% solvent and about 55% polymer; and about 50% solvent and about 50% polymer (with all percentages given in w/w ratios).
The vehicle may also include one or more surfactants. For example, surfactants may be included in the vehicle to facilitate release of a beneficial agent suspended in the vehicle once the suspension formulation is delivered to an environment of use. Alternatively, surfactants may be included in the vehicle to help maintain the stability of a beneficial agent suspended in the vehicle. Examples of surfactants that may be used in the vehicle include, but are not limited to, esters of polyhydric alcohols such as glycerol monolaurate, ethoxylated castor oil, polysorbates, esters or ethers of saturated alcohols such as myristyl lactate, CERAPHYL® 50, polyoxyethylenepolyoxypropylene block copolymers, TWEENs, SPANs, glyceryl caprylate, glyceryl laurate, PEG-8 caprylic capric glycerides, polyglyceryl-6 oleate, dioctyly sodium, sulfosuccinate, and Vitamin E TPGS. Where included, the surfactant(s) will typically account for less than about 20% (w/w), preferably less than 10% (w/w), more preferably less than 5% (w/w) of the vehicle.
The vehicle may also include one or more preservatives. Preservatives that may be used in the vehicle include, for example, antioxidants and antimicrobial agents. Examples of potentially useful antioxidants include, but are not limited to, tocopherol (vitamin E), ascorbic acid, ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, and propyl gallate. Where one or more preservatives are incorporated in the vehicle, the amount used will vary depending on the application, the preservative used, and the desired result. Generally, a preservative is included only in amounts sufficient to achieve the desired preservative effect.
A vehicle according to the invention may be a Newtonian or a non-Newtonian material, and the viscosity of the vehicle will vary. In each embodiment, however, a vehicle according to the invention is formulated to provide a viscosity that is capable of maintaining a desired suspension of a chosen particle formulation of interferon over a predetermined period of time, thereby facilitating creation of a suspension formulation tailored to provide controlled delivery of the interferon at a desired rate. Therefore, the viscosity of a vehicle according to the invention will vary depending on, among other factors, the desired application, the size and type of the dry particle formulation to be included in the vehicle, and the required vehicle loading. The viscosity of a vehicle according to the invention can be varied, as desired, by altering the type or relative amounts of solvent and polymer materials included in the vehicle. In one embodiment, the vehicle of the invention is formulated as a viscous vehicle, with the vehicle having a viscosity in the range of about 1 kP to 10,000 kP. Where the vehicle of the invention is formulated as a viscous vehicle, the viscosity of the vehicle preferably ranges from about 10 kP to 250 kP.
A vehicle according to the invention is preferably manufactured by combining the desired ingredients without the addition of water. Generally, vehicles according to the invention may be prepared by combining the dry (e.g., powdered or low moisture content) ingredients in a dry box or under other dry conditions and blending them at an elevated temperature, preferably about 40° C. to 70° C., to allow them to liquefy and form a single phase. Where the vehicle includes a surfactant, the solvent portion of the vehicle is preferably combined with the surfactant at an elevated temperature before the desired polymer material is added for blending. Blending of the ingredients can be accomplished using any suitable equipment, such as a dual helix blade mixer, and blending is preferably completed under vacuum to remove trapped air bubbles produced from the dry ingredients. Once a liquid solution of the vehicle ingredients is achieved, the liquid vehicle may be allowed to cool to room temperature. If desired, the liquid vehicle may be removed from the blending apparatus to allow for cooling. Differential scanning calorimetry may be used to verify that the components included in the vehicle have been combined such that a single-phase material is formed. The final moisture content of the vehicle is preferably less than 5 wt %.
A vehicle may be loaded with varying amounts of interferon that allows for dosing of the interferon over time. The amount of interferon included in a suspension formulation depends on, among other factors, the potency of the interferon, the desired duration of treatment, and the desired release rate of the interferon. Typically, a particle formulation of interferon accounts for between about 0.1% to 50% (w/w) of a suspension formulation according to the invention, with the vehicle accounting for between about 50% and 99.9% (w/w). In a preferred embodiment, a suspension formulation according to the invention includes between about 0.1% and 30% (w/w) of the particle formulation. In a more preferred embodiment, a suspension formulation according to the invention includes between 1% and 20% (w/w) of the particle formulation.
A particle formulation as described above may be dispersed in a vehicle as described above using any mixing, blending, or other dispersion technique that provides a suspension formulation having a desired distribution of the particle formulation. Preferably the particle formulation is dispersed within the vehicle using a process that does not require the addition of water. For instance, the particle formulation can be dispersed within a vehicle according to the invention by combining the vehicle with the particle formulation under dry conditions and blending the materials under vacuum at an elevated temperature, preferably about 40° C. to 70° C., until a desired dispersion of the particle formulation within the vehicle is achieved. The particle formulation and the vehicle may be blended using the same equipment and techniques used to blend the vehicle. In particular, a mixer, such as a dual helix blade or similar mixer, may be used to blend the particle formulation and vehicle to achieve a suspension formulation according to the invention. After blending at elevated temperatures, the resulting suspension formulation is allowed to cool to room temperature. After preparation, the suspension formulation may be sealed in a dry container to avoid undesired incorporation of moisture.
Suspension formulations of the invention are stable when maintained at elevated temperatures and serve to minimize the potential for partial or complete occlusion of the delivery passage of a delivery device from which the formulations are delivered. In preferred embodiments, the suspension formulation of the invention is formulated such that it remains chemically and physically stable for at least 3 months at delivery temperature and for at least 6 months at storage temperature. The delivery temperature could be normal body temperature, e.g., 37° C., or slightly higher than normal body temperature, e.g., 40° C. The storage temperature could be refrigeration temperature, e.g., around 5° C., or room temperature, e.g., around 25° C. The term “chemically stable” means that an acceptable percentage of degradation products produced by chemical pathways such as deamidation (usually by hydrolysis) or oxidation is formed. For example, a suspension formulation may be considered chemically stable if less than 35%, preferably no more than about 20%, and most preferably less than 10% breakdown products are formed after 3 months at delivery temperature and after 6 months at storage temperature. The term “physically stable” means that an acceptable percentage of aggregates (e.g., dimers and other higher molecular weight products) is formed. For example, a suspension formulation may be considered physically stable if less than 15%, preferably no more than 10%, more preferably less than 3%, aggregates are formed after 3 months at delivery temperature and 6 months at storage temperature.
In preferred embodiments, an interferon is chemically stable and bioactive after suspension in a vehicle of the invention for at least 3 months at 40° C. The term “bioactive” means that the interferon has biological activity as defined by clinical efficacy or an in vitro technique that shows activity. A cell-based assay may be used to demonstrate that the interferon is bioactive, i.e., has the ability to kill a specific type of virus. In preferred embodiments, soluble interferon is released from the formulation exiting a delivery device at target levels. For pump implants, few pumping failures are encountered during operation and implant can be manufactured aseptically with minimal bubbles in the suspension formulation. In preferred embodiments, adverse toxicity reactions are not detected from the suspension formulation.
Suspension formulations according to embodiments of the invention may be formulated for delivery from an implantable drug delivery device. The implantable drug delivery device may be embodied by any such device capable of delivering a flowable formulation at a controlled rate over a sustained period after implantation within a subject. One example of a suitable implantable drug delivery device is an osmotic pump implant, such as DUROS® pump developed by ALZA Corporation. Non-osmotic pump implants may also be used. The suspension formulation may be formulated for delivery at flow rates up to 5 ml/day, depending on the interferon to be delivered and the implantable drug delivery device used to deliver the suspension formulation. Where the interferon is delivered from an osmotic pump implant designed to provide low flow rates, the formulation is preferably formulated for delivery of between 0.25 and 5 μL/day, more preferably for delivery of between 0.5 and 2.0 μL/day, and most preferably for delivery between 1.0 and 1.5 μL/day. In one embodiment, a suspension formulation according to an embodiment of the invention is formulated to deliver interferon from an implanted device in a range from 1 ng/day to 600 μg/day over one month, preferably over three months, more preferably over 6 months, much more preferably over 9 months, and most preferably over one year.
In one embodiment, a suspension formulation of interferon is formed by dispersing a particle formulation of interferon as described above in a suspension vehicle as described above. Table 6 below shows dosage examples of suspension formulation of interferon for sustained delivery via an implantable drug delivery device. In a preferred embodiment, an implantable drug delivery device contains 0.5 to 2.5 mg IFN, e.g., IFN-ω, for sustained delivery at a delivery rate in a range from 0.25 to 5 μL/day, more preferably from 0.5-2.0 μL/day, most preferably from 1.0 to 1.5 μL/day
TABLE 6
MATERIAL
DOSAGE 1
DOSAGE 2
IFN-ω
2.3 mg (1.5%)
0.9 mg (0.6%)
Benzyl Benzoate, USP
69.8 mg (45.0%)
73.9 mg (47.7%)
Povidone, USP
71.0 mg (45.8%)
75.3 mg (48.6%)
Sucrose, NF
4.6 mg (3.0%)
1.8 mg (1.2%)
Methionine, USP
2.3 mg (1.5%)
0.9 mg (0.6%)
Sodium citrate, USP
4.5 mg (2.9%)
1.8 mg (1.2%)
Citric Acid Monohydrate, USP
0.5 mg (0.3%)
0.2 mg (0.1%)
The following stability examples are presented for illustration purposes and are not to be construed as limiting the invention as otherwise described herein.
A study was conducted to assess the stability of a particle formulation of IFN-ω suspended in a vehicle that is biocompatible, single-phase, and non-aqueous. The samples were analyzed using Size Exclusion Chromatography (SEC) and Reversed Phase High Performance Liquid Chromatography (RP-HPLC). For the analysis, IFN-ω is extracted from the suspension using 50:50 (v/v) of methylene chloride:acetone. The solvent dissolves the vehicle in the suspension and precipitates the protein. After several times of washing with the same solvent mixture, the protein precipitate is dried and then reconstituted in water for analysis. The monomeric and aggregated forms of IFN-ω were separated by the SEC method using TSK Super SW2000 column and detected with UV detection at 220 nm. The purity and identity of IFN-ω were determined by RP-HPLC on a Zorbax 300SB-C8 RP-HPLC column, at acidic pH and with UV detection at 220 nm.
Example 5
IFN-ω particle formulation (IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15) was suspended in LA/PVP vehicle with a target particle loading of approximately 10% (w/w). The average particle size of the IFN-ω particle formulation was 4-5 μm. Reservoirs of several osmotic pump implants, such as DUROS® pump developed by ALZA Corporation, were each filled with approximately 150-μL of the suspension. A cap with an orifice (e.g. diffusion moderator) was affixed to the open end of each reservoir, and the implants were placed into a stoppered and crimped glass vial for storage at 40° C. up to 24 weeks. Samples were extracted and analyzed at initial, 1, 2, 3 and 6 months using RP-HPLC. FIG. 4 shows percent main peak as a function of time. Percent main peak refers to the fraction of IFN-ω detected that is in a monomeric form and does not appear to be chemically degraded in any form. The results show that IFN-ω suspended in LA/PVP vehicle is stable out to 4 weeks at 40° C. For comparison purposes, FIG. 4 also shows percent main peak for the IFN-ω particle formulation without the vehicle.
Example 6
IFN-ω particle formulation (IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15) was suspended in CERAPHYL® 31/PVP vehicle with a target particle loading of approximately 10% (w/w). Reservoirs of several osmotic pump implants, such as such as DUROS® pump developed by ALZA Corporation, were filled with approximately 150 μL of the suspension and stored at 40° C. for 3 months. The samples were extracted and analyzed at initial, 1 month, 2 months, and 3 months. FIG. 5 shows monomer level as measured by SEC and purity level as measured by RP-HPLC. As shown in FIG. 5 , the suspension was relatively stable over 3 months at 40° C.
Example 7
The reservoir of an osmotic pump implant, such as DUROS® pump, was loaded with approximately 150 μL of the suspension described in EXAMPLE 6 and stored at 5° C. for 6 months (storage conditions). FIG. 6 shows the stability results. The results show that IFN-ω suspended in Ceraphyl® 31/PVP vehicle is stable when stored at 5° C. for 6 months. At 6 months, percent degradation products from oxidation was less than 2%, deamidation was about 2%, other related proteins was less than 9%, and dimers was less than 0.5%. A slight increase in percent degradation products from deamidation and dimers was observed under storage conditions, while percent degradation products from oxidation remained substantially unchanged. The percent degradation products from oxidation, deamidation, other related proteins, and dimers indicate that the suspension was relatively stable under storage conditions for 6 months.
Example 8
IFN-ω particle formulation (IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15) was suspended in BB/PVP vehicle with a target particle loading of approximately 10% (w/w). Reservoirs of several osmotic pump implants, such as DUROS® pump, were each filled with approximately 150 μL of the suspension. Some of the implants were stored at 40° C. for 161 days, while others were stored at 5° C. for 161 days. Samples were extracted and analyzed at initial, one and six months days using RP-HPLC. The stability results are shown in FIG. 7 . Relative stability out to six months are shown in FIG. 7 .
Example 9
Particle formulation of IFN-ω (IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15) was suspended in LL/PVP vehicle with a target particle loading of approximately 10% (w/w). Reservoirs of several osmotic pump implants, such as DUROS® pump, were filled with approximately 150 μL of the suspension and stored at 5° C., 25° C., or 40° C. for 180 days or 12 months. Samples were extracted and analyzed at various time points between initial and 180 days or 12 months using SEC or RP-HPLC. FIG. 8A shows stability of IFN-ω particle formulation in LL/PVP vehicle after storage of 6 months at 40° C. FIG. 8B shows percent degradation products from dimers, oxidation, deamidation, and other related proteins after storage of the suspension formulation for 6 months at 40° C. FIG. 8C shows protein content stability in LL/PVP vehicle after storage of 6 months at 40° C.
The following release rate examples are presented for illustration purposes and are not to be construed as limiting the invention as otherwise described herein.
A study was conducted to assess the release rate of suspension formulations according to embodiments of the invention using an implantable delivery device. The implantable delivery device selected for use is an osmotic pump, such as DUROS® pump developed by Alza Corporation. The osmotic pump includes a cylinder, made of titanium, having open ends. A diffusion moderator is mounted at a first end of the cylinder, and a semipermeable membrane is mounted at a second end of the cylinder. The diffusion moderator has a delivery conduit which allows fluid delivery from the interior to the exterior of the cylinder. The delivery conduit may be straight or spiral in shape. The semipermeable membrane forms a fluid-permeable barrier between the exterior and interior of the cylinder. A piston inside the cylinder defines a first compartment, which contains an osmotic agent, and a second compartment, which serves as the drug reservoir.
For the study, drug reservoirs of several osmotic pumps, such as DUROS® pumps, were filled with 150-μL of suspension formulation. The membrane ends of the osmotic pumps were placed into stoppered glass vials filled with 3 mL phosphate buffer solution (PBS), and the diffusion moderator ends of the osmotic pumps were placed into glass vials filled with 2.5 to 3 mL release rate medium (citrate buffer solution at pH 6.0 with 0.14 M NaCl and 0.2% sodium azide). The systems were placed into capped test tubes, with the diffusion moderator side down, and partially immersed in a 37° C. water bath. At specified time points, the glass vials at the diffusion moderator ends were replaced with new glass vials filled with 2.5 to 3 mL release rate medium (citrate buffer solution at pH 6.0 with 0.14 M NaCl and 0.2% sodium azide). Samples were collected from the diffusion moderator ends of the osmotic pumps and analyzed using RP-HPLC.
Example 10
Drug reservoirs of several osmotic pumps were filled with approximately 150 μL of suspension formulation as prepared in EXAMPLE 5, i.e., IFN-ω particle formulation (IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15) suspended in LA/PVP. Diffusion moderators with straight delivery conduits having a diameter of 0.25 mm and 0.38 mm and a length of 1.5 mm were used. FIG. 9 shows the release rate per day out to 90 days at 37° C. The release rate data indicate that the systems deliver IFN-ω near the target rate of 22 μg/day out to 90 days at 37° C.
Example 11
Drug reservoirs of several osmotic pumps were filled with approximately 150 μL of suspension formulation as prepared in EXAMPLE 6, i.e., IFN-ω particle formulation (IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15) suspended in LL/PVP. Diffusion moderators with spiral delivery conduits were used. FIG. 10 shows the release rate per day out to 110 days at 37° C. The release rate data indicate that the systems deliver IFN-ω near the target rate of 22 μg/day through at least day 95 at 37° C.
Example 12
Drug reservoirs of several osmotic pumps were filled with approximately 150 μL of suspension formulation as prepared in EXAMPLE 5, i.e., IFN-ω particle formulation (IFN-ω:sucrose:methionine:citrate in a ratio of 1:2:1:2.15) suspended in BB/PVP. Diffusion moderators with spiral delivery conduits were used. The target dose in this example was 25 μg/day. FIG. 11 shows the release rate per day out to 90 days at 37° C. The results indicate that the systems deliver IFN-ω near the target rate through day 90.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
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An implantable device includes a reservoir containing a suspension of an interferon in an amount sufficient to provide continuous delivery of the interferon at a therapeutically effective rate of 1 ng/day to 600 μg/day to maintain and achieve therapeutic blood or plasma levels of the interferon throughout a substantial period of the administration period.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for removal of condensate from a fluted drying cylinder.
2. Description of the Related Art
Known for solving the problem of evacuating the condensate accumulating in the interior of a steam-heated drying cylinder are already many different designs. The ultimate concern is to pass the condensate forming as the superheated steam introduced in the interior of the drying cylinder cools down to the outside (to a steam separator), in order to keep the inside wall of the drying cylinder, and thus the drying cylinder itself, as much as possible at a constant operating or working temperature. The superheated steam is supplied through a steam pipe situated coaxially to the bearing of the drying cylinder; the condensate itself passes via the condensate evacuation pipe to a collector and a hollow shaft mounted coaxially in the drying cylinder, whence the condensate is evacuated via a condensate discharge pipe which extends through the steam pipe or through the diametral end face of the drying cylinder.
The prior art relevant to "dewatering systems for fluted drying cylinders" includes three designs:
It is known to fix condensate collectors on the inside ribbing of the cylinder shell and to connect them to an inner hollow shaft. In the area of the hollow shaft, the connection is based on unique ball joint elements, and a length compensation element is provided toward the collector. In actual operation it has been demonstrated that the collector causes deformations of the cylinder shell. The result is a non-uniform and, as the case may be, incomplete dewatering, which ultimately may lead to a degraded paper quality.
Another known design comprises fastening the collector to the hollow shaft and supporting it on the covers of the drying cylinder; thus the cylinder is not in contact with the inside of the cylinder shell. This configuration has been found to be disadvantageous in that the position of the condensate pipes changes relative to the groove bottom, due to thermal expansion of the collector in transverse direction; the result again being a non-uniform and incomplete dewatering. Another difficulty with this design is that the bearing forces, or mass forces, of the collector burden the cylinder cover.
A third relevant concept is characterized in that the collectors are fixed only on the hollow shaft, making contact neither with the cylinder shell nor the cylinder covers. The dewatering itself takes place by way of extended dewatering tubes which protrude sideways from the collector, are fixed on the grooves of the cylinder shell and are adjustable relative to the groove bottom.
Viewed in terms of function, this prior design meets its objective in which context it is particularly noted that the long dewatering tubes assure a spatial degree of freedom. The disadvantage of this design is that the dewatering tubes are very complex and thus expensive components.
A problem underlying the present invention consists in providing a device for evacuating condensate from a fluted drying cylinder, wherein the condensate evacuation pipes functioning as dewatering tubes allow a simpler and thus more low-cost manufacture.
SUMMARY OF THE INVENTION
The present invention provides a flexible connecting element for establishing the functional connection of the condensate evacuation pipes to the collector within a drying cylinder of a paper machine.
The present invention consists in integrating the condensate evacuation pipes by way of an element for absorption and compensation of mechanical shifts between the condensate evacuation pipes and collector, thus safeguarding that the condensate evacuation pipes will at all times and under any given operating conditions be positioned at a constant spacing relative to the groove bottom.
Accordingly, two basic solutions consist in coupling the condensate evacuation pipes by way of a corrugated hose, as connecting hose or via a compensator, as compensating element, to the collector.
Advantages of the present invention include: 1) no or only little loading on the cylinder wall and cylinder covers; 2) adjustability of the condensate evacuation pipes relative to the groove bottom; and 3) simple exchangeability of condensate evacuation pipes in case of wear.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a schematic illustration of a drying cylinder of a paper machine in longitudinal section;
FIG. 2 is a side elevational view of an embodiment of the device for condensate removal of the present invention with the condensate evacuation pipes connected to the collector by a corrugated hose;
FIG. 3 is a perspective, sectional view taken along line A--A in FIG. 1;
FIG. 4 is a side elevational view, with the condensate evacuation pipes connected to the collector by way of a compensator;
FIG. 5 is a front longitudinal sectional view of the embodiment of FIG. 4;
FIG. 6 is a fragmentary side view a third embodiment of the device for condensate removal where the condensate evacuation pipes bear in fixed fashion on the inside wall of the drying cylinder;
FIG. 7 is a fragmentary, enlarged, longitudinal, sectional view of the third embodiment according to FIG. 6;
FIG. 8 is an enlarged sectional view of FIG. 6 with a different sealing variant of the condensate evacuation pipes;
FIG. 9 is an enlarged sectional view of a further variant to the third embodiment, with the condensate evacuation pipes connected directly to the collector; and
FIG. 10 is an enlarged sectional view of a further variant to the third embodiment, with the condensate evacuation pipes being curvilinear.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a drying cylinder referenced 1 overall and featuring in customary fashion an internally fluted (refer to FIGS. 2 through 5) cylinder shell 12 and, on each end, a cylinder cover with a pertaining hollow journal 13, 15, respectively. Drying cylinder 1 is heated with superheated steam D which proceeds through the one journal 15 (at the right in the drawing) into the interior of drying cylinder 1. The condensate forming inside drying cylinder 1 due to cooling is passed to a hollow shaft 17 by means of several condensate risers 14 which in spider fashion are distributed across the circumference. Hollow shaft 17 passes coaxially with the axis of rotation 10 of drying cylinder 1 through second journal 13 (at the left in the figure) and carries the condensate to a condensate evacuation line (refer to arrow X) which feeds it, e.g., to a steam separator. Hollow shaft 17 is mounted on journal 13 by means of a bracket 16 and extends outward, through the journal, where it hooks to condensate evacuation line X.
The radially outer ends of condensate risers 14 connect to a collector 18 which is spaced from the inside wall of drying cylinder 1 and extends as a single, or alternatively several pieces essentially across the entire length of drying cylinder 1. Collector 18, in turn, connects to a plurality of condensate evacuation pipes 20 (FIGS. 2 through 5), each of which is of assigned individually to a groove of the fluted inside wall drying cylinder 1 and extends into the groove. Condensate forming in the grooves is sucked into the condensate evacuation pipes due to the pressure difference between the interior of drying cylinder 1 and condensate evacuation line X, and passed outside via collector 18, condensate risers 14 and hollow shaft 17. (For the sake of completeness it is mentioned that the steam supply and condensate removal could take place also via a common, so-called steam head.)
An embodiment of the present invention is more particularly shown in FIGS. 2 through 5, which illustrate hereafter the details concerning the arrangement and coordination of condensate evacuation pipes 20 in drying cylinder 1. FIGS. 2 and 3 show two different basic illustrations of the functional connection between condensate evacuation pipes 20, and collector 18. Collector 18 connects via condensate riser 14 in fixed fashion to hollow shaft 17 without making contact with the inside wall of the cylinder, i.e., ribbing 22 of fluted cylinder shell 12. Collector 18 may basically have any geometric hollow shape.
Condensate evacuation pipes 20, individually or--as shown in FIG. 3--bundled, are fixed on ribbing 22 of cylinder shell 12 by means of a mounting strap 24 (FIG. 2) or a mounting bar 26 (FIG. 3). The dimensioning and mutual adaptation in width, of mounting strap 24 or mounting bar 26, are such that condensate evacuation pipes 20 are always allowed to freely enter grooves 23 and will not be affected in any way either by thermal expansion of the various components. Furthermore, condensate evacuation pipes 20 are connectable, and connected, to mounting strap 24, or mounting bar 26, in a way such that their penetration depth (.increment.) in respective groove 23 can be selected freely. This allows very specific adjustment of different thermal drying conditions across the width of drying cylinder 1.
In view of the embodiments relative to FIGS. 2 and 3, one aspect of the present invention consists in coupling condensate evacuation pipes 20 to collector 18 through a corrugated hose 30, which absorbs virtually any relative motion between cylinder shell 12 and collector 18 as well as hollow shaft 17. Corrugated hose 30 is attached to condensate evacuation pipe 20 and sideways, i.e., parallel to the peripheral direction of cylinder shell 12, a protruding port of collector 18 by means of a union nut 31. This allows ultimately also a simple exchange or replacement of condensate evacuation pipes 20 in case of wear and/or other damage.
The dewatering concept for drying cylinders of paper machines as illustrated with the aid of FIGS. 2 and 3 thus avoids application of forces upon cylinder shell 12. As a result, thermal expansions of the components may be disregarded.
FIGS. 4 and 5 show a cross section analogous to FIG. 2 and a longitudinal section analogous to FIG. 3, the second embodiment of the functional connection between the condensate evacuation pipes 20, and collector 18. As illustrated in FIG. 1, collector 18 connects to the hollow shaft by way of condensate riser 14. Condensate evacuation pipes 20 are now fixed on ribbing 22 of cylinder shell 12, the same as in FIGS. 2 and 3, with a mounting strap 24 or--bundled--a mounting bar 26, notably screw-joined. Condensate evacuation pipes 20 are coordinated with groove 23, adjustable in height as well as indicated by the .increment. symbol.
In the embodiment according to FIGS. 4 and 5, condensate evacuation pipes 20 have an axially parallel orientation relative to condensate riser 14, and the flexible connecting element between condensate evacuation pipes 20 and collector 18 are fashioned each as a compensator 40. Compensator 40 is hooked to the conjugate inlet of collector 18 and, in the assembly of drying cylinder 1, is fixed on a flanged projection 42 of condensate evacuation pipes 20. This differs from the object of the invention relative to the embodiment according to FIGS. 2 and 3 in that the flexible connecting element is not directly a part of the condensate discharge, but participates only indirectly as far as the transition from condensate evacuation pipe 20 to collector 18 is tight in relation to the interior of drying cylinder 1. Also with the embodiment according to FIGS. 4 and 5, no appreciable forces act upon cylinder shell 12. Any problems associated with thermal expansion are eliminated, and wear and/or damage are prevented.
FIGS. 6 through 10 show further presentations of the functional connection between condensate evacuation pipes 20 and collector 18. Condensate evacuation pipes 20 rest on the inside wall of drying cylinder 1 and bear on two ribs 22 that bound groove 23. This bearing contact is accomplished through a washer 4 attached to each condensate evacuation pipe 20. Instead of washer 44, condensate evacuation pipe 20 may be alternatively fashioned with an integral collar or the like. In order for washer or collar 44 to firmly bear on the inside wall, each condensate evacuation pipe is provided with a compression spring 55 bearing on washer 44 and wall 50 of collector 18 as seen in FIG. 9, or wall 52 of connection box 43 attached to side wall 51 of collector 18 (FIGS. 6 and 7).
Spring 55 enables that at any time, a definitive penetration depth of condensate evacuation pipe 20 in the relevant groove 23 is formed. This also assures that the condensate accumulating in grooves 23 will be evacuated outside through collector 18, condensate risers 14 and hollow shaft 17 in case of thermal expansion or other positional changes (mechanical shifts) of the various components and that thereby the desired (for instance uniform) depth of the remaining condensate film is assured in all grooves.
Essentially, condensate evacuation pipes 20 are arranged so as to be movable relative to collector 18, radially in relation to the peripheral direction of cylinder shell 12. Thus, they are well suited to compensate for movements of collector 18 relative to drying cylinder 1. Likewise assured is a constant tight connection between condensate evacuation pipes 20 and collector 18, or connection boxes 43 attached to its side wall 51. For that purpose, packings 45 are recessed in lower wall 50 of collector 18 (FIG. 9) or lower wall 52 of connection box 43 (FIG. 6 and 8), through which wall extends condensate evacuation pipe 20. Packings 45 are of the sliding type, made of bronze, teflon or similar material. They may be used in the form of O-rings (FIG. 6) or sleeves (FIG. 8 and 9). O-rings allow for any skewing of collector 18 relative to cylinder wall 12.
Illustrated in FIG. 9, additionally, is a flexible finger 58 arranged on the end of condensate evacuation pipe 20 that protrudes into collector 18. This avoids a dropping out of condensate evacuation pipes 20 in the assembly of collector 18.
Yet another option to compensate for the above relative movements is illustrated in FIG. 10. To that end, condensate evacuation pipe 20 has a curvilinear, respectively meandering or looping shape and is relatively elastic. On one end it is tightly and rigidly connected to side wall 51 of collector 18 by a screw joint 59. The other end extends first with play through a stay 60 attached to side wall 51 of collector 18 and serving to support compression spring 55 (such as in FIGS. 6, 7 and 9 on lower wall 50 or 52), and it is arranged--the same as in the aforementioned embodiments according to FIGS. 6 through 9--at a defined, desired distance from the groove bottom. This variant allows an easier manufacture and assembly and there are no wearing packings needed as in the other embodiments. Besides, the curved shape of condensate evacuation pipes 20 allows greater absorption and compensation of the relative movements than before.
A common feature of FIGS. 2, 3, 6-8, and 10 is that the condensate does not flow into collector 18 from below, but sideways. This facilitates any required exchange of a condensate evacuation pipe 20 (e.g., with a different penetration depth). Such exchange may also be necessitated by clogging of a condensate evacuation pipe 20 after extended use.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
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The invention is directed to a device for evacuating condensate from a rotary, steam-heated drying cylinder or the like, in particular the drying cylinder of a paper machine, having a plurality of grooves provided at the inner wall in the circumferential direction of the cylinder jacket, and a condensate evacuation pipe which may be associated with the grooves and which supplies the condensate produced to a collector and then to a condensate discharge pipe. The condensate evacuation pipes are fixed in the area of the associated grooves at a predetermined distance from the bottom of the grooves. A flexible connection element functionally connects the condensate evacuation pipes to the collector.
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There are no related patent applications.
This patent application did not receive any federal research and development funding.
BACKGROUND OF THE INVENTION
The invention generally relates to a rotary piston engine. More particularly, the invention relates to a rotary piston engine that includes an air chamber for storing pressurized air that is routed into a separate combustion chamber for ignition purposes. The engine includes a housing that surrounds at least one rotor coupled to a piston for driving a shaft that may be coupled to a drive assembly for harnessing rotational energy produced by the rotor. A movable valve door provides a base against which expanding gases react to force the piston in a forward direction. The valve door is drawn away from the shaft to allow the piston to pass-by to complete a revolution.
Internal combustion engines are typically referred to as either a reciprocating piston engine or a rotary piston engine. Reciprocating piston engines use crank gears to translate movement of pistons into a rotary motion. The use of crank gears in a rotary piston engine is unnecessary since the piston performs a rotary motion during operation.
The most popular rotary engine, the Wankle rotary engine, includes a piston having a cross-section similar to a triangle and rotates in a uniquely shaped cylinder. Because of the unique shape of the cylinder, it encounters sealing problems that result in high fuel consumption. Most known rotary piston engines are complex and require high production and maintenance costs.
It should be noted that the discussion of the rotary engine in the present invention is not limited to internal combustion engines. The present invention may be modified to be powered by air, geothermal energy or the like.
BRIEF SUMMARY OF THE INVENTION
The present invention is a rotary engine that includes separate air and fuel combustion chambers. Pressurized air is pumped into an air chamber that stores the air until completion of a firing cycle. The pressurized air is then routed into a combustion chamber and mixed with fuel to be combusted. Expanding gases from the combustion chamber are directed into a cylinder defined by a housing. A movable valve door provides a surface against which the gases react to force a piston and rotor around a crankshaft. The crankshaft may be coupled to a drive assembly for use in harnessing the energy produced by the engine.
The rotary engine includes a housing that defines a working cylinder in which a piston and rotor rotate. The piston and rotor are coupled to a crankshaft. A valve door is operablely disposed within the cylinder such that it is withdrawn from the cylinder to allow the piston to pass between the rotor and the valve door to complete a revolution. A lifter comprises a gear that is rotated in opposite directions to raise and lower the valve door such that it moves towards and away from the crankshaft to optimize the amount of energy that is directed against the piston. Through series of multiplier gears, the amount of movement necessary to lift the valve door is minimal.
It is an object of the invention to provide a rotary engine that has separate air pressurizing and fuel/air mixing chambers.
It is a further object of the invention to provide a rotary engine that includes a novel lifter mechanism for withdrawing a valve door from the working cylinder of the piston.
It is an additional object of the invention to provide a rotary engine that is high torque engine having greater fuel efficiency and less energy losses than rotary engines of the past.
It is another object of the invention to provide a simplified rotary engine that is less costly to produce and maintain while maximizing an amount of energy realized during combustion of fuel.
Additional objects and advantages 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 from practicing the invention. The objects and advantages of the invention will be obtained by means of instrumentalities in combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1A is a front elevation view of the engine of the present invention and having protective shielding installed.
FIG. 1B is a side elevation view of the engine shown in FIG. 1 A.
FIG. 2A is a right side elevation view of the engine shown with the protective shielding removed.
FIG. 2B is a front elevation view of the engine shown in FIG. 2 A.
FIG. 2C is a right side elevation view of the engine shown with a flywheel and ignition coil removed.
FIG. 2D is a front elevation view of the engine shown in FIG. 2 C.
FIG. 2E is a left side elevation view of the engine shown in FIG. 2 C.
FIG. 3A is a front elevation view of the engine shown with a timing system and a front rotor plate removed.
FIG. 3B is a back elevation view of the engine shown in FIG. 3A with an air compressor and back plate removed.
FIG. 3C is a right side elevation view of the engine shown in FIG. 3A with an outer center rotor case and the head for the combustion chamber removed.
FIG. 3D is a left side elevation view of FIG. 3 C.
FIG. 4A is an enlarged front elevation view of the valve system.
FIG. 4B is an enlarged back elevation view of the valve system.
FIG. 4C is a top plan view of the valve system shown in FIGS. 4A and 4B .
FIG. 4D is a left side elevation view of the cam gear system.
FIG. 4E is a front elevation view of the lifter and cam track shown in FIG. 4 D.
FIG. 5A is an exploded view of the rotor and rotor case components taken from the side.
FIG. 5B is a partial exploded view of the rotor and rotor case components shown in FIG. 5 A. In this Figure, the rotor seal vane attaches to the rotor.
FIG. 5C is an exploded view of the valve door shown in FIG. 5 B.
FIG. 5D is an exploded view of the piston assembly.
FIG. 5E is an exploded view of the rotor and the rotor seal vanes.
FIG. 5F is an exploded view of the vane seal for the top of the piston.
FIG. 5G is an enlarged view of a seal for sealing the outer rotor case near where the valve door operates.
FIGS. 6A through 6D depict the timing rotation of the piston and valve system including valve door during one rotation of operation.
FIG. 7 an elevation view of the compression pump.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1A shows the engine of the present invention. The engine 1 comprises an outer casing including a rotor case 8 , a flywheel housing 36 and a valve cover 5 . Each of these protects internal working parts by preventing foreign debris or materials from coming into contact with the internal workings of the engine. The various casings, housings and covers may be attached by known means such as bolts, screws, clips, fasteners or other such securing means.
In this embodiment, the engine 1 is shown as a gasoline type of engine. However, it may be noted that the engine may be modified to be driven with air, diesel, battery or steam. One of ordinary skill in the art can readily recognize that modifications may be undertaken to allow the engine to be driven by various propellants or forms of energy.
The upper portion of the engine comprises an air chamber 4 defined by head 63 . Air flows into air chamber 4 through air intake vent 14 for use in the combustion process. Typically head 63 is constructed of a light-weight metal such as cast steel or aluminum and may include an inner liner of composite material for preventing expansion of the head when pressure within the air chamber 4 is increased. Head bolts 49 secure the head 63 to the engine 1 and allow access to the inner air chamber for maintenance or other such reasons.
A combustion chamber 13 is provided opposite the air chamber 4 for combustion of fuels. Fuel is injected into the combustion chamber 13 along with pressurized air provided from the air chamber 14 before combustion. A spark plug 3 electronically controls the firing or combustion of the pressurized fuel within the combustion chamber 13 . The unique design of the engine 1 separates the operation of pressurizing air and fuel into different chambers. In other engines, this step is achieved by pressurizing a fuel/air mixture within a piston chamber by compressing the fuel/air mixture with the piston. A head 64 defines the combustion chamber 13 and includes bolts 49 for allowing access to the combustion chamber for maintenance purposes.
A lower portion of the engine 1 includes an oil reservoir 18 for storing a lubricant that is used to reduce internal friction and wear of the moving parts. Bolts 53 secure the engine case to prevent access to the internal workings of the engine. These bolts 53 may be removed to allow maintenance of the internal workings as necessary. Mounting bolts 50 are provided for securing the engine 1 in a desired location. An exhaust port 16 expels combusted gases from the interior of the engine.
In FIG. 1B , the engine is shown from the side. A dipstick 9 is provided for measuring the level of lubricant necessary for operating the engine. The dipstick 9 may include marks that indicate the level of lubricant within the oil reservoir 18 .
A throttle control 11 controls the amount of air that is drawn into air chamber 4 for proper mixture of the fuel-to-air ratio. By controlling oxygen that is fed into the air chamber 4 , the fuel-to-air ratio may be manipulated to control the revolutions of the piston. That is to say, the amount of pressure exerted onto the rotor may be controlled by manipulating the airflow into the air chamber 4 .
A fuel injector 12 controls the amount of fuel flowing into the combustion chamber 13 . The fuel injector 12 is controlled by a microprocessor, not shown. A fuel pump, not shown, pressurizes the fuel such the injector 12 may open and close in a rapid succession to create an aerosol spray of fuel that is supplied to the combustion chamber 13 .
Now turning to FIGS. 2A through 2E , that show the various views of the engine 1 with the outer protective casings removed. A compression pump 10 communicates with the air intake vent 14 to draw in air, compress it and force air into air chamber 4 . The compression pump 10 is discussed in greater detail in FIG. 7 . In one embodiment, the compression pump 10 is coupled to the crankshaft 2 and driven by the engine 1 . However, it can be easily recognized that other compression pumps or compressors may be electrically driven to supply pressurized air to the air chamber. A pressure feed tube 54 is provided for transporting pressurized air from the compression pump 10 to the air chamber 4 .
A back rotor plate 62 and front rotor plate 61 provide support for the piston rotor 42 , shown in FIG. 3 A. The rotor plates 61 , 62 provide a sealed lubricating chamber in which piston rotor 42 travels around.
A timing belt 40 is driven by the crankshaft 2 to control the timing of the firing and pressurized air inflow sequences. The timing belt 40 overlaps both timing gears 20 B and 20 A. Timing gear 20 B is coupled to the crankshaft 2 for driving the timing belt 40 and causing it to drive timing gear 20 A. Timing gear 20 A is coupled to camshaft 24 for controlling the operation of camshaft 24 . Camshaft 24 is retained by bolts 52 .
An ignition coil 7 is coupled to spark plug 3 for providing an electric pulse thereto. The ignition coil 7 generates an electric pulse as the flywheel 65 passes near the coil 7 in a known fashion. The ignition coil 7 is secured by bolts 51 .
Flywheel 65 stores and provides rotational energy for driving the engine. The flywheel 65 comprises magnets that provide a magnetic pulse to the ignition coil 7 as the flywheel 65 passes near the coil 7 . This magnetic pulse is relayed from the ignition coil 7 to the spark plug 3 for combustion purposes. A crankshaft nut 6 secures the flywheel 65 and the crankshaft 2 .
Now turning to FIG. 2C , an idle pulley adjustment device 44 is provided for adjusting tension on the timing belt 40 . This device 44 exerts constant pressure onto the timing belt 40 to prevent it from slipping from gears 20 A and 20 B.
An oil pump 43 is also driven by timing belt 40 to cause pressurized lubricant to be forced through a series of lubricating orifices, not shown. The oil pump 43 draws oil from the oil reservoir 18 and routes it to specific areas within the engine 1 . A moon key 41 is inserted into an opening in the crankshaft 2 for ensuring that the flywheel 65 is maintained in a proper relationship to crankshaft 2 .
FIG. 3A shows a front elevation view of the internal workings of the engine 1 . In this view, the timing system and a front rotor plate is removed. Motor mount 15 comprises the motor mount casing to provide a stable support that holds the engine in a fixed position during operation. Piston 38 attaches to rotor 42 to drive the rotor 42 in a circular manner. Rotor seal 58 is disposed between the piston 38 and rotor 42 to ensure proper sealing of the rotor 42 with the outer casing to prevent leakage of gases that drive the piston 38 . The rotor seal may comprise a composite, metal, rubber, fiberglass or other such known material. Both the piston 38 and the rotor 42 comprise a track or guide, not shown, for accepting the rotor seal 58 .
Valve door 29 moves towards and away from the crankshaft 2 to direct the flow of gases or other propellants towards the backside of the piston 38 . Thus, the valve door 29 provides a base against which the explosion of fuel reacts to propel the piston 38 in a forward direction. The valve door 29 also acts to prevent propellants from flowing in a wrong direction. The valve door 29 includes a valve rail 48 ensuring proper alignment of the valve door 29 as it is lifted away from the crankshaft 2 during a completed rotation of the rotor 42 and allowing the piston 38 to pass.
An exhaust check valve spring 32 maintains proper tension on the exhaust check valve 23 to prevent leakage of propellants from the combustion chamber 13 . The exhaust check valve 23 seals the combustion chamber and is forced open when combustion of the propellants occurs to allow the expanding gases to be directed into the rotor case to drive the piston 38 . An exhaust input 46 directs these expanding gases between the piston 38 and the valve door 29 .
Check valve spring 55 biases check valve 21 to allow pressured air to flow from air chamber 4 into combustion chamber 13 while preventing a back flow of gases and propellants from the combustion chamber 13 into air chamber 4 . Pressurized air conduit 35 directs air from the air chamber 4 into the combustion chamber 13 .
Valve rocker arm 31 attaches at one end to exhaust check valve 23 and at a second end to cam lobe 5 to control the opening and closing of the exhaust valve 23 to direct propellants against the piston 38 . Cam lobe 57 comprises the camshaft 24 . The cam lobe 57 controls the opening and closing of the exhaust check valve 23 in a known manner.
Lifter 25 controls opening and closing of the valve door 29 . The lifter 25 comprises a gear that is rotated in opposite directions to raise and lower the valve door 29 such that it moves towards and away from the crankshaft 2 to optimize the amount of energy that is directed against the piston 38 . Through series of multiplier gears 26 and 27 , the amount of movement necessary to lift the valve door 29 is minimal. That is to say, a maximum of 20 degrees of rotation of the cam 24 causes the valve door 29 to be lifted and lowered to complete one revolution of the piston 38 .
Air chamber check valve spring 33 prevents leakage of pressurized air from air chamber 4 . When the internal pressure of air chamber 4 exceeds a predetermined threshold, check valve 22 opens to allow pressurized air to flow from the air chamber 4 through conduit 35 into combustion chamber 13 . It should be noted that check valve 22 and check valve 23 are arranged such that only one can open at a given time. That is to say, both check valves 22 and 23 cannot be open at the same moment in time. FIG. 4B is an enlarged back elevation view of the valve system that more clearly depicts cam track 39 . FIG. 4C is an overhead plan view of the arrangement of parts in the valve system of FIGS. 4A and 4B . Bearings, not shown are provided for securing camshaft 34 in place.
FIGS. 4D and 4E show the cam gear system and arrangement of gears for actuating the various parts. In FIG. 4D rotation from cam shaft 24 is translated to cam track 39 and cam lobe connector 57 . Cam track 39 drives lifter 25 which connects to gear 26 via a common shaft. Lifter 25 drives gear 26 . Gear 26 is coupled to gear 27 via a second shaft to drive it. Therefore, gears 26 and 27 increase or multiple rotational movement of gear 25 . This rotational movement is translated into linear movement by gear track 28 for raising and lowering the valve door 29 , as previously discussed. FIG. 4E shows the arrangement of lifter 25 and cam track 39 .
FIG. 5A is an exploded view of the rotor 42 and rotor case assembly. Front rotor plate 61 includes a valve track 30 . Back rotor plate 62 also includes a valve track 30 . These valve tracks operate as previously discussed to allow movement of the valve door 29 towards and away from the crankshaft 2 . Front and back rotor plates 61 and 62 connect to outer rotor case 56 . A pair of rotor seal vanes 58 is disposed against the rotor 2 to prevent gases from leaking between the rotor 2 , piston 38 and the housing, as previously discussed. Springs 59 are arranged at various locations on the rotor 2 to bias the vanes 58 towards the plates 61 and 62 to ensure a proper seal.
A seal vane 37 is provided for sealing between the valve door 29 and the rotor 42 to prevent leakage of gases therebetween. The arrangement of the seal vane 37 and valve door assembly is more clearly shown in FIG. 5 C. FIG. 5B is a partial exploded view of the rotor and rotor case components with the rotor seal vane 58 in place.
FIG. 5C is an exploded view of the valve door assembly. The valve door 29 includes gear track 28 that couples to gear 27 as shown in the previous figures. A pair of valve rails 48 attach to sides of the valve door 29 by screws 47 . Seal vane 37 attaches to an inner or bottom portion of the valve door 29 via screws 45 . It should be noted that the valve door 29 includes a recess for accommodating the vane 37 . Springs 59 are disposed between the vane 37 and the recess of the valve door 29 as shown. These springs 59 force the vane 37 away from the valve door 29 to ensure a proper seal when the valve door 29 and rotor 42 meet.
FIG. 5D shows the piston assembly. The vane seal 60 for the piston 38 is seated between the piston 38 and the outer rotor case 56 , shown in FIG. 5A. A pair of springs 67 are disposed against a pair of screws 66 that secure the piston 38 to the rotor 42 . The vane seal 60 prevents leakage of gases between the piston 38 and the outer rotor case 56 . Ends of the vane seal 60 contact the rotor vane seals 58 to seal the piston 38 . Piston 38 includes a lower extension that locks the piston 38 into the rotor 42 , as shown. The vane seal 60 includes recesses on either end as shown for accepting end caps 69 as shown in FIG. 5 F. As more clearly seen in FIG. 5F , the rotor vane seals 58 include keys 68 for accepting seal 60 . Springs 70 are disposed between end caps 69 and seal 60 . The end caps 69 are seated in recesses within the seal 60 .
FIG. 5G shows the outer rotor case seal 72 that seats within a recess provided in the outer rotor case 56 . A plurality of springs 71 are disposed between the recess and the seal 72 . Not shown are the input and output openings for depositing combusting fuel into the rotor casing 56 and exhausting spent fuel therefrom.
FIG. 5E is an exploded view of the piston showing the rotor seal vanes 58 in relation to the piston 38 . Each rotor seal vane 58 includes a key 68 that mates with a lip on the piston 38 to ensure that each vane 58 moves in concert with the piston 38 . Causing the vanes 58 to move with the piston 38 prevents a buildup of internal friction between the rotor 38 and the vane 58 .
FIGS. 6A through 6D show a timing cycle of operation for the piston and valve assembly. In FIG. 6A , the piston 38 is shown at approximately 300 degrees into the operation cycle. The exhaust valve 23 is held open by the rocker arm 31 that is being operated by the cam lobe 57 . During the operating cycle, the air chamber 4 is being pressurized by the air pump 10 through pressure feed tube 54 . The valve 23 prevents port valve 22 from opening to allow the pressurized air to flow into the combustion chamber 13 . Air in front of the piston 38 is forced from the exhaust port 16 to prevent a build up of pressure in front of the piston 38 .
In FIG. 6B , the piston 38 is shown at approximately 350 degrees. In this view, exhaust check valve 23 is forced shut by the biasing force of exhaust check valve spring 32 as controlled by the valve rocker arm 31 which is driven by cam lobe connector 57 . Pressure from the air chamber 4 forces the port valve 22 open allowing pressurized air to flow from the air chamber 4 into combustion chamber 13 . Check valve 21 is also forced open until pressure within each chamber becomes equalized. When pressure is normalized between the chambers, a biasing force from the springs 33 and 55 closes each valve 21 and 22 .
In FIG. 6C , the piston 38 has completed one revolution and returns to zero degrees. The lifter 25 is already activated to open the valve door 29 preventing the rotor piston 38 from contacting it and becoming damaged. In other words, the valve door 29 moves away from the rotor 42 to allow the piston 38 to complete a cycle. At this time, all pressure created by combustion of the fuel has been expended and released.
In FIG. 6D , the piston 38 is at approximately ten degrees. Valve door 29 has returned to its normal position and is shut. Fuel injector 12 injects fuel into the combustion chamber 13 . Check valve 23 is biased shut by spring 32 until fuel within the combustion chamber 13 is ignited. Upon ignition of the fuel, the valve 23 is forced open to allow expanding gases to flow from the combustion chamber 13 into the space between the valve door 29 and the piston 38 . The force from the expanding gases is exerted against the backside of the piston 38 causing it and the rotor 42 , as well as the crankshaft 2 , to rotate. During this process, spent fuel from the previous burning cycle is forced from the exhaust port 16 .
FIG. 7 is a plan view of the air compressor shown without a housing. An intake check valve 100 allows air to flow into the compressor while preventing it from flowing outward through the intake. An output port 101 directs compressed air from the compressor into the pressure feed tube 54 and connects thereto. An output check valve 102 allows air to be forced outward through output port 101 whilst preventing it from flowing from the air chamber 4 back into the compressor.
Piston 103 moves towards and away from the inner cam 112 that is sleeved onto the crankshaft 2 . Piston rod 104 connects to piston 103 for forcing the piston 103 towards or away from the outer cam lobe 111 . Roller pin 105 connects to the piston rod 104 to run along the outer perimeter of the outer cam lobe 111 to compress air. The compressor mounts to the engine via mounts 106 as shown in FIG. 2 A.
Piston rod track 107 includes a groove that prevents the roller pin. 105 from turning in an undesirable direction. The piston rod spring 108 maintains pressure between the piston 103 and the outer cam lobe 111 . It also forces the piston 103 towards the inner cam 112 . Head bolts 109 maintains the upper heads of the piston 103 in place and allows access for maintenance. Intake screen 110 prevents debris and foreign objects from entering intake check valve 100 .
It is to be understood that the invention is not limited to the exact construction illustrated and described above, but that various changes and modifications may be made without departing from the spirit and the scope of the invention as defined in the following claims.
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A rotary engine includes separate chambers for receiving pressurized air and fuel. An air chamber stories pressurized air that is routed into a combustion chamber to be mixed with fuel for combustion to drive a piston. The combustion chamber is forced open during a firing cycle to allow expanding gases into a piston chamber. A valve door serves as a base against which the expanding gases react to force a piston in a forward direction. The piston is coupled to a crank shaft which may in turn be coupled to a transmission or other power drive device to harness energy created by the turning crankshaft. A lifter includes a gear that rotates to raise and lower the valve door such that it moves towards and away from the crankshaft to optimize the amount of energy that is directed against the piston. Through series of multiplier gears, the amount of movement necessary to lift the door is minimal.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of earlier filed U.S. patent applications Ser. No. 09/489,805 filed on Jan. 24, 2000 and 09/519,559 filed on Mar. 6, 2000, both herein incorporated by reference in their entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] The United States Government has rights in this invention pursuant to contract DE-AC05-00OR22725 between the United States Department of Energy and UT-Battelle, LLC.
BACKGROUND OF THE INVENTION
[0003] The present invention generally relates to pretreatment of fuel cell feed airstreams and specifically to a device and method for humidifying an airstream to a fuel cell using porous carbon foam.
[0004] Conventional methods for humidifying air involve spraying water over a high surface area medium (cloth, steel wool, etc) and forcing the dry supply air over the moist medium, which results in evaporation of the water from the surfaces of the medium, thereby producing humid air suitable for the supply of a fuel cell. However, the drawbacks to these conventional methods are that the evaporation of the water from the evaporating medium produces an endothermic effect and the medium chills dramatically, albeit very slowly due to its low conductivity. The results of this cooling effect is that the supply air cools and reduces the saturation point of the air (which results in a lower humidity content once the air is heated going into the fuel cell) and the cooled evaporating medium and water present then have a lower thermodynamic driving force to evaporate. Attempts to overcome this by heating the evaporative medium have been unsuccessful since the traditional evaporative mediums exhibit low thermal conductivities, which result in high losses and low efficiency of supplying the heat of vaporization to the water/medium. If the medium is a cheap steel wool or cloth fabric, the thermal conductivity can be as low as 1 watt per meter per degree Kelvin (W/m·K). If the medium is an expensive aluminum or copper foam (which is not the traditional choice), the thermal conductivities are not much better at about 10-20 W/m·K. Conversely, by utilizing a high conductivity graphite foam, the thermal conductivity can be as high as 187 W/m·K. This order of magnitude higher conductivity results in more heat being applied to the water for evaporation from the heat source, thus the system doesn't cool and the air reaches a higher content of humidity.
SUMMARY OF THE INVENTION
[0005] The unique properties of graphitic foam used in the humidifier of this invention are derived from the fact that the foam is not stabilized during the carbonization cycle, unlike all prior mesophase pitch foams. This allows extremely large ligament thermal conductivities, greater than 1700 W/m·K. This translates to a thermal conductivity in the bulk material up to 187 W/m·K at densities around 0.6 g/cm 3 . This extraordinary thermal conductivity, combined with its open surface area of more than 2×10 6 m 2 /m 3 , yield a material which is uniquely suited for heat and moisture transfer.
[0006] This invention overcomes the problems associated with traditional humidification techniques by utilizing the graphite foam to act as both a water management material as well as a heat management device. By using the high conductivity of the foam ligaments, the foam can efficiently transfer heat from a hot source to the water on the surface of the ligaments to effect the evaporation and, thus humidification. More importantly, the advantage of significantly more surface area for this evaporation than traditional devices, will allow a smaller humidifier as well as the ability to capture waste heat to drive the humidification.
[0007] The invention comprises a method and apparatus of supplying humidified air to a device or process. The extremely high thermal conductivity of some graphite foams lends itself to enhance significantly the ability to humidify supply air for a fuel cell. By utilizing a high conductivity graphite foam, thermal conductivity being as high as 187 W/m·K, the heat from the heat source is more efficiently transferred to the water for evaporation, thus the system does not cool due to the evaporation of the water and, consequently, the air reaches a higher humidity ratio.
[0008] The humidifier comprises a first pitch-derived graphitic carbon foam element, a means for heating said first foam element, a means for wetting said first foam element, and a means for increasing the humidity ratio of an airstream passed through said first foam element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] [0009]FIG. 1 is a flow diagram of an embodiment of the invention using power electronics as a heat source.
[0010] [0010]FIGS. 2A through 2D are photographs of various finned carbon foam element structures.
[0011] [0011]FIG. 3 is a flow diagram of an invention embodiment using fuel cell cooling water as a heat source.
[0012] [0012]FIG. 4 shows two photographs of a carbon foam radiator used in one embodiment of the invention.
[0013] [0013]FIG. 5 is a flow diagram of an invention embodiment using an inlet air preheater.
[0014] [0014]FIGS. 6A and 6B show two flow arrangements for the preheater.
[0015] [0015]FIG. 7 is a flow diagram of an invention embodiment that recovers condensed moisture from the fuel cell exhaust in a condenser.
[0016] [0016]FIG. 8 is a psychrometric chart showing the thermodynamic properties of the air humidified by the embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] In the present invention, humidification is accomplished by the transferring of heat from a heat source such as fuel cell cooling water, a resistance heating device, power electronics, etc., through the foam ligaments to the moisture entrained on the surface of the foam. This heat is used to overcome the latent heat of vaporization of the water, and thus the system remains isothermal during operation (i.e. does not cool), or it heats. The high surface area of the foam enhances the evaporative effect in that a high surface area to volume of water can be deposited on the foam. The extreme high conductivity of the ligaments (greater than 5 times that of copper) ensures efficient transfer of heat from the source to the water and reduces losses.
[0018] [0018]FIG. 1 illustrates the first embodiment of the humidifier 20 in the present invention. For illustrative purposes, the heat from the onboard power electronics 14 is used as the heat source. High conductivity graphite foam 10 is attached to the surface of the spreader plate 12 opposite the power electronics 14 heat source by some means of joining. This foam is ducted in some fashion such that air can be forced through the foam structure. A water supply system 16 is used to add water to the foam at 18 . If the foam is properly surface treated (i.e. oxidation at 500° C. for more than 8 hours), the water will wick up through the pores of the foam and be then evaporated as the forced dry air 11 is passed through the foam. A blower/compressor 13 is used to bring in filtered ambient air and force it through the foam. As the air is forced through the foam, the heat from the heat source 14 heats it. Concurrently, the heat from the heat source combined with the now lower humidity level of the incoming air, result in evaporation of the water added to the system. The exiting air 15 is now both heated and closer to the desired humidity of the fuel cell inlet air. Preferably, the inlet air is heated prior to entering the humidifier, by such means as using the exhaust products of the fuel cell. This will result in a “dryer” air flowing over the moist foam, and in turn, result in more moisture being evaporated into the air stream.
[0019] The method of attaching the foam to the heat source is important, but not critical. The preferred method is brazing since it creates a strong thermally conductive interface, but other means such as epoxy are acceptable if the bondlines are thin (i.e. less then 1 mil=2.54 EE-05 meters). The thinner the bondline, the less important the thermal conductivity of the bond material is to the overall conductance of the system.
[0020] The foam is preferably machined such that it is a finned structure, more preferable the finned structure resembles a pin-fin structure as shown in FIG. 2D. However, configurations such as the solid block of FIG. 2A, vertical blind holes of FIG. 2B, and straight fins of FIG. 2C are possible. This pin-fin structure reduces the pressure drop through the foam, and therefore reduces the parasitic losses on the compressor/blower. In a solid foam structure, the pressure drop can be as high as 2 pounds per square inch (psi) per inch of thickness whereas in a finned structure in can be less than 0.05 inches water per inch of thickness. Therefore, a compressor would be required for the system with a solid foam and only a blower would be required for the system with the finned structure. It is obvious that there are many more means of reducing pressure drop by changing the design of the foam structure, and most will be suitable for this system.
[0021] It is important to note that in most fuel cells, a compressor will already be required to supply the filtered inlet air if ambient air is used, especially on an automobile, airplane, or ship. It is likely that since the pressure drop of this humidifier can be designed to be very low, the same compressor already in use or currently designed will be suitable. Therefore, this embodiment did not increase the parasitic losses of the fuel cell significantly, but increased its overall efficiency by increasing the humidity level of the inlet air.
[0022] It is also important to note that in portable fuel cells, like that in an automobile, it is generally understood that onboard supply of water will be required for the humidification of the ambient air. Therefore, the system of this invention has not required any extra water to be carried with the automobile. It is generally understood that you will have to fill up the water at the same time as you will fill up the fuel for the fuel cell.
[0023] In another embodiment of the present invention, a similar design is used, but in conjunction with the cooling water of the fuel cell and the radiator (which can be made from high conductivity carbon foam itself). FIG. 3 is a schematic of the second embodiment. This inlet air (considered dry ambient air) 11 is passed through a similar humidifier 20 as in FIG. 1, but with the heat source being the hot cooling fluid 32 exiting the fuel cell 30 . The hot cooling fluid 32 supplies enough heat for the humidification process with a similar foam structure on the fluid side (i.e. pin-fin). Depending on the inlet air humidification needs (which is dependent on the ambient humidity), the fuel cell cooling fluid will still need to be cooled further by a radiator 31 . The humid fuel cell inlet air 15 is then supplied to the fuel cell 30 , as needed, along with optional additional fuel 36 to enable the fuel cell energy production before leaving the fuel cell as exhaust 38 . Again, as in FIG. 1, the compressor already required for the inlet air will be sufficient to force the inlet air through the humidifier and the water supply 16 for the humidifier is already required. Therefore, there is no extra parasitic loss on the system, but waste heat from the fuel cell is recovered to improve it efficiency by increasing the humidity level, and hence extra power is not used to humidify the inlet air as in current systems.
[0024] In this embodiment, the fuel cell cooling fluid leaving the humidifier is then sent to a radiator 31 for further cooling. Preferably, this is a heat exchanger made with graphite foam as shown in FIG. 4. This heat exchanger exhibits heat transfer coefficients up to two orders of magnitude greater than existing radiators and therefore, the size of the system is about ⅕th that of the current systems. This also leads to smaller fans for forcing the air over the radiator and therefore reduces parasitic losses commonly associated with the cooling system.
[0025] In another embodiment, the inlet air to the humidifier is first heated by a preheater 50 using the exhaust of the fuel cell 30 as in FIG. 5, preferably using a carbon foam air-air heat exchanger as shown in FIG. 6. The preheater 50 can be either a crossflow arrangement of FIG. 6A or a counter-current flow of FIG. 6B. The hot inlet air is now “drier” and can accept more moisture, resulting in a higher humidity content in the inlet air to the fuel cell. This will result in even higher efficiencies.
[0026] In yet another embodiment, the preheater 50 heat exchanger used to preheat the inlet air to the humidifier can double as a condenser 70 to condense moisture 72 entrained in the fuel cell exhaust gasses, as seen in FIG. 7. While a chilled condenser will be most efficient, cooling to ambient conditions should be enough to recapture a significant amount of the supplied water in the humidifier, thereby recycling most of the water and reducing losses. This also reduces the amount of water needed to be supplied to the vehicle at the time of fuel “fill-ups.”
[0027] [0027]FIG. 8 shows example psychrometrics of the supply air to the fuel cell. Under conventional un-heated adiabatic humidification, air enters the humidifier at 20° C. dry bulb, 0.0006 kg/kg dry air humidity ratio (state point 1 ) and leaves the humidifier at 13.5° C., 0.0009 kg/kg (state point 2 ). One embodiment of the instant invention in FIG. 3 provides a means for isothermal humidification wherein the air conditions leaving the humidifier are 20° C., 0.013 kg/kg (state point 3 ), thereby improving the moisture content (humidity ratio) and dry bulb temperature of the supply air for improved fuel cell performance. Another embodiment of the instant invention in FIGS. 5 and 7 preheats the supply air to 25° C. (state point 4 ) and then isothermally humidifies the air to 25° C., 0.018 kg/kg (state point 5 ), thereby further improving the moisture content of the supply air for greater fuel cell performance.
[0028] A unique feature is the use of the carbon foam to capture waste heat from onboard systems (such as cooling fluids and power electronics and exhaust gases) and utilize it efficiently (more than an order of magnitude better than metallic systems) to humidify the inlet air to a fuel cell. By having a more humid inlet air, the fuel cell experiences less drying of the proton exchange membrane (PEM) elements and therefore experiences a higher conversion of the fuel to electricity. This, and the fact that it is using waste heat, rather than electricity to power systems to humidify, results in a higher efficiency of the fuel cell and better fuel mileage.
[0029] There are many alternatives, but the general idea of capturing waste heat from the exhaust gases, cooling fluids, and power electronics is the same. The specific dimensions and geometries of the heat exchangers, methods of delivery of the water, and pumping systems may be different, but do not deviate from the intent of this invention.
[0030] Carbon foam used in the humidifier was examined with photomicrography, scanning electron microscopy (SEM), X-ray analysis, and mercury porisimetry. The interference patterns under cross-polarized light indicate that the struts of the foam are completely graphitic. That is, all of the pitch was converted to graphite and aligned along the axis of the struts. These struts are also similar in size and are interconnected throughout the foam. This would indicate that the foam would have high stiffness and good strength. The foam is open cellular meaning that the porosity is not closed. Mercury porisimetry tests indicate that the pore sizes are in the range of 90-200 microns.
[0031] A thermogravimetric study of the raw pitch was performed to determine the temperature at which the volatiles are evolved. The pitch loses nearly 20% of its mass fairly rapidly in the temperature range between about 420° C. and about 480° C. Although this was performed at atmospheric pressure, the addition of 1000 psi pressure will not shift this effect significantly. Therefore, while the pressure is at 1000 psi, gases rapidly evolved during heating through the temperature range of 420° C. to 480° C. The gases produce a foaming effect (like boiling) on the molten pitch. As the temperature is increased further to temperatures ranging from 500° C. to 1000° C. (depending on the specific pitch), the foamed pitch becomes coked (or rigid), thus producing a solid foam derived from pitch. Hence, the foaming has occurred before the release of pressure and, therefore, this process is very different from previous art.
[0032] Samples from the foam were machined into specimens for measuring the thermal conductivity. The bulk thermal conductivity ranged from 58 W/m·K to 187 W/m·K. The average density of the samples was 0.53 g/cm 3 . When weight is taken into account, the specific thermal conductivity of the pitch derived from foam is over 4 times greater than that of copper. Further derivations can be utilized to estimate the thermal conductivity of the struts themselves to be nearly 700 W/m·K. This is comparable to high thermal conductivity carbon fibers produced from this same ARA24 mesophase pitch.
[0033] X-ray analysis of the foam was performed to determine the crystalline structure of the material. From this data, the graphene layer spacing (d 002 ) was determined to be 0.336 nm. The coherence length (L a,1010 ) was determined to be 203.3 nm and the stacking height was determined to be 442.3 nm.
[0034] The validity of the flash diffusivity method and whether the open porosity would permit penetration of the heat pulse into the sample had to be established. Deep penetration of the pulse in samples typically causes a change in the characteristic heat pulse on the back face of the sample. Thus, errors in the reported diffusivity can be as high as 20%. However, the rather large struts and small openings of the foam limits the depth of penetration to about one to two pore diameters (250 - 500 micrometers), or less than 2% penetration. Therefore, it was believed that this technique would yield a fairly accurate value for the thermal conductivity. This was confirmed by testing samples with both the flash diffusivity method and the thermal gradient method. The measured conductivities varied by less than 5%, verifying the flash method as a viable method to measure these foams. If the pore structure changes significantly, the flash method will likely yield inaccurate results. The bulk thermal conductivity of the graphitized ARA24 foam, graphitized at 4° C./min, was in the range of approximately 146 to 187 W/m·K. This is remarkable for a material with such a low density of approximately 0.56 g/cm 3 . This calculates as a bulk specific thermal conductivity in the range of approximately 256 to 334 W/m·K/g/cm 3 . The foam exhibits thermal conductivies comparable to the in-plane thermal conductivity of some other thermal management materials and significantly higher than in the out-of-plane directions of the other thermal management materials. Although several of the other thermal management materials have higher in-plane thermal conductivities, their densities are much greater than the foam, i.e., the specific thermal conductivity of the foam is significantly greater than all the available thermal management panels. In fact, the specific thermal conductivity is more than seven times greater than copper (45 W/m·K), the preferred material for heat sinks. It is clear that for thermal management, where weight is a concern or where un-steady state conditions occur often, the graphitic foam is superior to most other available materials. The advantage of isotropic thermal and mechanical properties should allow for novel designs that are more flexible and more efficient.
[0035] Another property that affects the overall thermal performance of the carbon foam is the specific surface area (SSA), calculated by:
SSA [m 2 /m 3 ]=Total Pore Area [m 2 /g]×Estimated Density [g/cm 3 ]×1,000,000 [cm 3 /m 3 ]
[0036] Smaller specific surface areas indicate a lower foam pororsity which reduces the effect of the natural convective heat transfer mode (laminar flow) and allows the more efficient conductive heat transfer mode to dominate thermal performance. Larger SSA's enhance evaporative cooling via increased surface area to volume ratio and increasing the contact area between the evaporative fluid and the foam material. SSA is also be an indicator of the foam's response to forced convective heat transfer (turbulent flow) via fluid passing through the media by increasing the surface area used for heat transfer. The SSA varies in the range of approximately 19,440 m 2 /m 3 to approximately 43,836,000 m 2 /m 3 .
[0037] Lattice parameters were determined from the indexed diffraction peak positions. The X-ray method for crystallite size determination has been extensively reviewed elsewhere. The 002 and 100 diffraction peak breadths were analyzed using the Scherrer equation to determine the crystallite dimensions in the a- and c- directions.
t = 0.9 λ B cos ( 2 θ )
[0038] where t is the crystallite size, λ is the X-ray wavelength, B is the breadth of the diffraction peak [full width half maximum (FWHM) minus the instrumental breadth], and 2θ is the diffraction angle. The 002 peak (which is characteristic of interlayer spacing), was very narrow and asymmetric, indicative of highly ordered graphite. The interlayer spacing calculated with the Scherrer method in the range of approximately 0.3354 nm to 0.3362 nm. The crystallite size in the c-direction was calculated from these data to be at least approximately 82.4 nm, and the 100 peak (or 1010 in hexagonal nomenclature) was used to calculate the crystallite size in the a-direction of at least approximately 21.5 nm. These crystallite sizes are larger than typical high thermal conductivity carbon fibers and therefore, the foam ligaments should perform similarly to high order pyrolytic carbon and high thermal conductivity carbon fibers such as K1100 and vapor grown carbon fibers (VGCF).
[0039] The “doublet” at the 100 and 101 peaks is characterized by a relative peak split factor (RPSF) parameter, or narrowness, calculated using the peak angles and the full width half maximums (FWHM). The equation is:
RPSF = ( FWHM 101 2 + FWHM 100 2 ) 2 θ 100 - 2 θ 101
[0040] A smaller RPSF indicates closer peaks at 100 and 101 and favorable lattice conditions for thermal conductivity and structural integrity. The data shows a RPSF of at most approximately 0.298, but a least in the range of 0.298 to 0.470.
[0041] The compression strength of the samples was measured to be 3.4 Mpa and the compression modulus was measured to be 73.4 Mpa. The foam sample was easily machined and could be handled readily without fear of damage, indicating good strength.
[0042] It is important to note that when this pitch is heated in a similar manner, but only under atmospheric pressure, the pitch foams dramatically more than when under pressure. In fact, the resulting foam is so fragile that it could not even be handled to perform tests.
[0043] It is obvious that other materials, such as metals, ceramics, plastics, or fiber-reinforced plastics could be bonded to the surface of the foam of this invention to produce a foam core composite material with acceptable properties. It is also obvious that ceramics, or glass, or other materials could be impregnated into the foam for densification.
[0044] Based on the data taken to date from the carbon foam material, several observations can be made and the important features of the invention are:
[0045] 1. Pitch-based carbon foam can be produced without an oxidative stabilization step, thus saving time and costs.
[0046] 2. High graphitic alignment in the struts of the foam is achieved upon graphitization to 2500° C., and thus high thermal conductivity and stiffness will be exhibited by the foam, making them suitable as a core material for thermal applications.
[0047] 3. High compressive strengths should be achieved with mesophase pitch-based carbon foams, making them suitable as a core material for structural applications.
[0048] 4. Foam core composites can be fabricated at the same time as the foam is generated, thus saving time and costs.
[0049] 5. Rigid monolithic preforms can be made with significant open porosity suitable for densification by the Chemical Vapor Infiltration method of ceramic and carbon infiltrants.
[0050] 6. Rigid monolithic preforms can be made with significant open porosity suitable for activation, producing a monolithic activated carbon.
[0051] 7. It is obvious that by varying the pressure applied, the size of the bubbles formed during the foaming will change and, thus, the density, strength, and other properties can be affected.
[0052] The process involves the fabrication of a graphitic foam from a mesophase or isotropic pitch which can be synthetic, petroleum, or coal-tar based. A blend of these pitches can also be employed. The simplified process utilizes a high pressure high temperature furnace and thereby, does not require and oxidative stabilization step. The foam has a relatively uniform distribution of pore sizes (˜100 microns), very little closed porosity, and density of approximately 0.53 g/cm 3 . The mesophase pitch is stretched along the struts of the foam structure and thereby produces a highly aligned graphitic structure in the struts. These struts will exhibit thermal conductivities and stiffness similar to the very expensive high performance carbon fibers (such as P-120 and K1100). Thus, the foam will exhibit high stiffness and thermal conductivity at a very low density (˜0.5 g/cc). This foam can be formed in place as a core material for high temperature sandwich panels for both thermal and structural applications, thus reducing fabrication time. By utilizing an isotropic pitch, the resulting foam can be easily activated to produce a high surface area activated carbon. The activated carbon foam will not experience the problems associated with granules such as attrition, channeling, and large pressure drops.
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A method and apparatus of supplying humid air to a fuel cell is disclosed. The extremely high thermal conductivity of some graphite foams lends itself to enhance significantly the ability to humidify supply air for a fuel cell. By utilizing a high conductivity pitch-derived graphite foam, thermal conductivity being as high as 187 W/m·K, the heat from the heat source is more efficiently transferred to the water for evaporation, thus the system does not cool significantly due to the evaporation of the water and, consequently, the air reaches a higher humidity ratio.
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This application claims the benefit of U.S. Provisional Application No. 60/093,317, filed Jul. 20, 1998, and which is herein incorporated by reference in its entirety
This invention was made with Government support under Contract DE-AC04-94AL85000 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the recovery of methane (natural gals) by sub-sea mining of clathrates.
2. Description of the Art Practices
U.S. Pat. No. 5,660,603 issued to Elliot et al., Aug. 26,1997 discusses a process for separating components of gas mixtures which have different hydrate forming characteristics using an aqueous liquid to absorb one of the gases preferentially by attaining conditions slightly above the catastrophic point at which gas hydrates form. Specifically, the separation of gas mixtures containing light hydrocarbons and carbon dioxide is accomplished without significantly reducing the pressure of the carbon dioxide or without requiring significant amounts of heat energy for regeneration.
U.S. Pat. No. 5,473,904 issued Dec. 12, 1995 to Guo et al., discloses a method of forming clathrate hydrates further by pressurizing a hydrate-forming gas, cooling liquid water below the gas-water-hydrate equilibrium curve, combining the hydrate-forming gas and the liquid water while locally supercooling the gas, and thereby forming a clathrate hydrate.
U.S. Pat. No. 4,376,462 issued Mar. 15, 1983 to Elliott et al., describes a method and apparatus for producing gaseous hydrocarbons from formations comprising solid hydrocarbon hydrates located under either a body of land or a body of water. In the Elliott et al., process warm brine or water brought down from an elevation above that of the hydrates, through a portion of the apparatus, passes in contact with the hydrates and melts them. The liquid then continues up another portion of the apparatus, carrying entrained hydrocarbon vapors in the form of bubbles, which can easily be separated from the liquid. After a short startup procedure, the process and apparatus are substantially self-powered by virtue of pressure differences. A related disclosure to U.S. Pat. No. 4,376,462 issued Mar. 15, 1983 to Elliott et al., is found in Elliott et al., in U.S. Pat. No. 4,424,858 issued Jan. 10, 1984.
An article in the Journal of Petroleum Geology, vol. 19(1). January 1996, pp. 41-56 OCEANIC METHANE HYDRATES: A “FRONTIER” GAS RESOURCE authored by Max et al., discusses the chemistry of methane hydrates. Max et al., article discloses that methane hydrates are ice-like compounds consisting of natural gas (mainly methane) and water, whose crystal structure effectively compresses the methane; each cubic meter of hydrate can yield over 150 cubic meters of methane. The hydrates cement sediments and impart considerable mechanical strength; the fill porosity and restrict permeability.
An article entitled Methane Hydrate, A Special Clathrate: Its Attributes and Potential by Max et al., dated Feb. 28, 1997 discusses the recovery and processing of methane hydrate. Similar disclosures are also made by Max et al., in an article entitled Oceanic Gas Hydrate: Guidance for Research and Programmatic Development for work done at the Naval Research Laboratory bearing a date of Dec. 31, 1997. Further disclosures are made by Max et al., in a chapter entitled Natural gas hydrates: Arctic and Nordic Sea potential in Arctic Geology and Petroleum Potential edited by T. O. Vorren et al.
The need remains for effective processes to be developed to allow the hydrocarbon gas trapped in the ice like stricture of the clathrate and the sediment to be effectively mined and separated. The present invention deals with one such effective method of the recovery of the hydrocarbon gases from the sea floor.
To the extent that the foregoing references are relevant to the present invention, they are herein specifically incorporated by reference. Measurements herein are stated in degrees of approximation and where appropriate the word “about” may be inserted before any measurement.
SUMMARY OF THE INVENTION
Described herein is an apparatus, according to the present invention, for recovering hydrocarbons from a hydrocarbon containing clathrate, the apparatus comprising:
mining means, for when said apparatus is in operation, disrupting a clathrate rich portion comprising the hydrocarbon containing clathrate and sediment from the surrounding strata,
transporting means for moving a clathrate rich portion comprising the hydrocarbon containing clathrate and sediment,
conduit means for receiving the hydrocarbon containing clathrate and sediment; and,
injection means having a point of injection for injecting an injection gas into said conduit.
Also described is a pressure- and/or temperature-related method of recovering hydrocarbons from a hydrocarbon-containing clathrate including the steps of:
disrupting a clathrate rich portion comprising the hydrocarbon containing clathrate and sediment from the surrounding strata,
transporting said clathrate rich portion into a conduit,
said conduit extending between a first region of high pressure and a second region of lower pressure,
injecting an injection gas into said conduit to aid in moving said clathrate rich portion from the region of high pressure to the region of low pressure,
separating at least a portion of the sediment in said clathrate rich portion from said hydrocarbon containing clathrate; and,
recovering said hydrocarbon from said hydrocarbon containing clathrate.
The present invention further describes a temperature-related method of recovering hydrocarbons from a hydrocarbon-containing clathrate including the steps of:
disrupting a clathrate rich portion comprising the hydrocarbon containing clathrate and sediment from the surrounding strata,
transporting said clathrate rich portion into a conduit,
said conduit extending between a first region of low temperature and a second region of high temperature,
injecting an injection gas into said conduit to aid in moving said clathrate rich portion from the region of low temperature to the region of high temperature,
separating at least a portion of the sediment in said clathrate rich portion from said hydrocarbon containing clathrate; and,
recovering said hydrocarbon from said hydrocarbon containing clathrate.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings. The drawings, which are incorporated into and form a part of the specification, illustrate embodiments of the present invention, and together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:
FIG. 1 shows the basic design of an apparatus, according to the present invention, for recovering a hydrocarbon from a hydrocarbon containing clathrate. FIG. 1A shows the point of injection of the supply gas below the point at which the conduit receives the hydrocarbon. FIG. 1B shows the point of injection at the hydrocarbon-receiving point. FIG. 1C shows the injection point above the hydrocarbon-receiving point.
FIG. 2 shows a second embodiment of an apparatus, according to the present invention, for recovering a hydrocarbon from a hydrocarbon containing clathrate.
DETAILED DESCRIPTION OF THE INVENTION
As previously discussed, the invention deals with recovering hydrocarbons from hydrocarbon-containing clathrate. Generally, the invention involves mechanically mining the clathrate (comprising, for example, hydrocarbon hydrate) using means for disrupting clathrate-rich sediments found at or near the surface of the sea floor. Such mechanical mining can be accomplished in any of a variety of ways consistent with the principles set forth in this disclosure. Among these ways are included various continuous mining techniques including, for example, grinding using a rotary tilling drum, and blasting high-pressure fluid against the surfaces of strata located at the sea floor, and drilling. Two of these approaches are illustrated as preferred embodiments, below. The embodiments are intended to be illustrative although not limitative of the principles of the invention.
According to the invention, sediments including clathrate-rich material disturbed from the sea floor are carried upward, with the aid of injection gas. As the disturbed material travels upward through regions of decreasing pressure, increasing temperature, or both, the clathrates and sediment separate and gaseous hydrocarbons are liberated as the clathrates dissociate. Sediments eventually fall and return to the sea floor. Gaseous hydrocarbons freed from the clathrates are collected by methods well known to those skilled in the art of offshore gas recovery. The water component and other non-gaseous-hydrocarbon components of the former clathrates remain in the sea water.
FIG. 1 illustrates one of the preferred embodiments. The subsea platform 20 has, for example, a three-dimensional generally trapezoidal base 22 wherein four generally trapezoidal sides are adjoined to an upper surface 32 and form an enclosure that is open in a plane generally defined by the lower edges 24 of the four sides (as described in greater detail below). However, a differently-shaped enclosure of any size and shape suited to the invention principles, including a three-dimensional generally rectangular enclosure or a generally cylindrical enclosure, could be used in place of the three-dimensional generally trapezoidal base 22 without departing from the intended scope of the invention.
In the embodiment illustrated in FIG. 1, the four sides of the three-dimensional generally trapezoidal base 22 of the subsea platform 20 are of approximately equal dimensions. The lower edges 24 of the four sides of the subsea platform 20 combine to form generally a square. The area enclosed by the perimeter defined by the lower edges 24 of the four sides of the subsea platform 20 is open to permit, when the apparatus is in operation, free access to the sea floor. In this embodiment, the area enclosed by the perimeter defined by the lower edges 24 of the four sides is greater than the surface area of the upper surface 32 .
As shown in the Figure, the subsea platform 20 has an upper surface 32 . The upper surface 32 of the subsea platform 20 is generally square. The upper surface 32 of the subsea platform 20 is substantially air tight. It is possible, consistent with the principles of the invention to substitute in place of a planar upper surface 32 , any substantially air tight upper region through which may pass the features below described as passing through the upper surface 32 . One possible option includes having a dome-shaped upper region.
Across two opposing sides of the subsea platform 20 is mounted a rotary tilling drum 60 . In other embodiments wherein differently-shaped enclosures are employed as the platform 20 , the drum 60 can be mounted in various orientations so that the drum is extends substantially across the platform base 20 in a plane generally parallel to that defined by the open portion of the platform. The rotary tilling drum 60 has a series of cutting surfaces, which in the preferred embodiment are helical cutting surfaces 64 . An example of such helical cutting surfaces is what are known to those skilled in the art of continuous mining as “endless helical cutting surfaces.” The helical cutting surfaces 64 of the rotary tilling drum 60 each have an outer surface 66 . The outer surfaces 66 of the helical cutting edge, when rotated to the lowermost position in the operational orientation of the apparatus, extend slightly below the plane formed by the lower surface 24 of each of the four lower edges of the three-dimensional generally trapezoidal base 22 .
A power source (not shown) provides power to turn the rotary tilling drum 60 . In the preferred embodiment, the power source also provides power for the subsea platform 20 to move across the sea floor.
An injection gas supply line 80 extends through the upper surface 32 of subsea platform 20 . An upper region 84 of the injection gas supply line 80 connects with a supply of gas (not shown). A lower region 88 of the injection gas supply line 80 connects with the upper region 84 of the injection gas supply line 80 to permit, when in operation, communication of the gas from the upper region 84 of the injection gas supply line 80 to the lower region 88 of the injection gas supply line 80 . In the embodiment of the invention shown in FIG. 1A, an opening 92 in the lower region 88 of the injection gas supply line 80 is within the confines of the three-dimensional generally trapezoidal base 22 . In cases where differently shaped enclosures are used, the lower region 88 of the injection gas supply line 80 is similarly within the confines of the enclosure. In another embodiment of the invention, shown in FIG. 1B, the opening 93 for injecting the gas supply is at the point at which the conduit receives the hydrocarbon. In yet another embodiment of the invention, shown in FIG. 1C, the point of injection 94 is above the point at which the conduit receives the hydrocarbon.
A conduit 100 is connected with the upper surface 32 of subsea platform 20 . The conduit 100 preferably has a generally cylindrical lower conduit segment 104 . The generally cylindrical lower conduit segment 104 has an opening 108 . The generally cylindrical lower conduit segment 104 communicates with the confines of the base 22 by means of the opening 108 .
The conduit 100 includes an intermediate chamber 120 , which in the preferred instance is generally spherical. The intermediate chamber 120 shown illustrated in the Figure has a larger diameter than the conduit 100 . The generally spherical intermediate chamber 120 has an upper half 124 and a lower half 128 . The upper half 124 of the generally spherical intermediate chamber 120 is substantially air tight.
The lower half 128 of the generally spherical intermediate chamber 120 has a series of port openings 132 . The series of port openings 132 permit, when the apparatus is in operation, communication between the lower half 128 of the spherical intermediate chamber 120 and the surrounding sea.
In the operative orientation of the apparatus, the generally spherical intermediate chamber 120 is positioned above the generally cylindrical lower conduit segment 104 . The generally spherical intermediate chamber 120 communicates with the generally cylindrical lower conduit segment 104 .
A generally cylindrical upper conduit segment 130 is connected with the generally spherical intermediate chamber 120 . The generally spherical intermediate chamber 120 communicates with the generally cylindrical upper conduit segment 130 . The generally cylindrical upper conduit segment 130 extends to the surface of the sea. In the region of the surface of the sea the generally cylindrical upper conduit segment 130 connects with a compressor (not shown).
The purpose of the present invention is the recovery of a hydrocarbon from a hydrocarbon containing clathrate. In operation, the three-dimensional generally trapezoidal base 22 of subsea platform 20 rests on the sea floor in an area determined to be rich in the desired hydrocarbon containing clathrate.
The power source (not shown) provides power to turn the rotary tilling drum 60 . The turning of the rotary tilling drum 60 causes the series of helical cutting surfaces 64 to turn. The outer surfaces 66 of helical cutting surfaces 64 contact the strata on the sea floor. The strata comprise the hydrocarbon containing clathrate and sediment. The hydrocarbon containing clathrate is largely hydrocarbon and water. The hydrocarbon is mostly methane, propane, isopropane, butane, isobutane, pentane and isomers of pentane.
The turning of the rotary tilling drum 60 comminutes the strata into fragments of the clathrate and sediment to generate a clathrate rich portion. Larger rocks and other sea floor debris are not affected by the turning of the rotary tilling drum 60 .
The turning of the rotary tilling drum 60 provides upward movement (toward the surface of the sea) of the clathrate rich portion. The currents generated by the turning of the rotary tilling drum 60 sweep the clathrate rich portion toward the opening 108 in the generally cylindrical lower conduit segment 104 . In the preferred embodiment, the three-dimensional generally trapezoidal configuration of the base 22 is beneficial in that the angle of the sides in relation to the sea floor may assist in channeling the clathrate-rich portion toward the generally cylindrical lower conduit segment 104 .
The injection gas supply line 80 is opened a short time before or after or at the time the rotary tilling drum 60 begins operation. The injection gas utilized in the injection gas supply line 80 is conveniently methane, propane, isopropane, butane, isobutane, pentane and isomers of pentane. Compressed air supplied either by a line from the surface or from storage tanks on the subsea platform can also be utilized in place of the gases just mentioned. The injection gas used in the injection gas supply line 80 is conveniently a portion of the hydrocarbon gas recovered from the process of the present invention. Although gases such as compressed air, nitrogen, carbon dioxide and combustion gases generated from burning hydrocarbon may be employed herein, such gases would have to be separated from the hydrocarbon gases recovered from the clathrate rich portion, or maintained at satisfactorily low levels so as not to significantly reduce the value of the recovered gases. In the case wherein compressed air is used, precautions known to those skilled in the art of hydrocarbon extraction must be taken to avert combustion hazards.
The injection gas supply line 80 provides a supply of injection gas from the surface of the sea through the upper region 84 of the injection gas supply line 80 to lower region 88 of the injection gas supply line 80 . The injection gas from the lower region 88 of the injection gas supply line 80 exits an opening 92 in the lower region 88 of the injection gas supply line 80 . The injection gas which exits the opening 92 in the lower region 88 of the injection gas supply line 80 enters the confines of the base 22 .
The injection gas exiting the opening 92 in the lower region 88 of the injection gas supply line 80 aids in sweeping the comminuted fragments of the clathrate and sediment from the strata toward the opening 108 in the generally cylindrical lower conduit segment 104 . The injection gas from the injection gas supply line 80 then aids in transporting the comminuted fragments of the clathrate and sediment from the strata upward (toward the sea surface).
The clathrate ordinarily begins to decompose as the ambient pressure is reduced or the ambient temperature increases. Typically, the pressure will be reduced by about one atmosphere for each 10 meters that the clathrate rich portion rises toward the sea surface. The temperature will also generally rise as the clathrate rich portion rises toward the sea surface.
Thus, as the clathrate rich portion rises toward the sea surface within the generally cylindrical lower conduit segment 104 it begins to generate the hydrocarbon gas and water. As the clathrate rich portion generates the hydrocarbon gas, this added source of hydrocarbon gas aids in carrying the clathrate rich portion toward the surface.
The sediment loosely adhering to the clathrate begins to separate as the ambient temperature rises or the ambient pressure decreases. The clathrate rich portion continues to rise and is largely decomposed before it enters the generally spherical intermediate chamber 120 . The generally spherical intermediate chamber 120 has a larger diameter than the lower conduit 100 . The generally spherical intermediate chamber 120 is an area of turbulent flow due to the increase in diameter and change in flow direction. The generally spherical intermediate chamber 120 is provided to allow disengagement of gas from sediment particles.
The liquid and sediment particles flow out of the series of port openings 132 in the lower half 128 of the generally spherical intermediate chamber 120 . Sediment that passes through the series of port openings 132 falls back to the sea floor by gravitational force. Some sediment is also likely to fall back into the generally cylindrical lower conduit segment 104 and ultimately to the sea floor.
The series of port openings 132 also serves a safety function. If the partial pressure of the gas generated from the clathrate and the partial pressure of the injection gas are too great the conduit 100 may rupture. While the pressure of the injection gas may be controlled it is much more difficult to control the gas generated from the clathrate. Thus, if the total gas pressure in the generally spherical intermediate chamber 120 is too great, venting of the gas is permitted through series of port openings 132 .
The power source also preferably provides power for the subsea platform 20 to move across the sea floor. As a consequence of the subsea platform 20 moving across the sea floor, new areas may be mined for the clathrate while the sediment is deposited.
A second embodiment of the invention is shown in FIG. 2 . Although the apparatus of the second embodiment is generally similar to the first embodiment a different mechanism is employed for disrupting the clathrate rich portion of the clathrate-containing strata
The subsea platform 20 has a base 22 similar to that described for the previously disclosed embodiment, with features including sides and an upper surface 32 , generally describing an enclosure that is open to the sea floor. Again, various other enclosure configurations will fall within the scope of the invention and appended claims, as described above for the previous embodiment exemplified by FIG. 1 .
In this embodiment instead of the using a rotating drum, the apparatus includes a fluid jet tube 200 which may extend substantially from the sea surface through the upper surface 32 of the subsea platform 20 . Alternatively, the fluid jet tube could extend from a location below the sea surface, for example, in a case wherein the fluid to be used in the jet tube is seawater. An example of this case is using a pump located in the region of the platform 20 wherein water is pumped from the environment near the sea floor into the fluid jet tube 200 and carried into the enclosure beneath the platform via the opening 92 . In all cases, though, the fluid jet tube 200 is connected with a source of fluid. This fluid is typically a liquid, preferably aqueous in nature.
The fluid jet tube 200 preferably extends from the fluid source (not shown) to about one-half meter above the sea floor. The fluid in the fluid jet tube 200 is supplied under pressure. The supply pressure for the fluid in the fluid jet tube 200 is conveniently from about 2 to about 1,000 times the ambient pressure of the sea floor that is being mined.
Certain other features illustrated in FIG. 2 are similar in orientation, structure and function to analogous features described above in conjunction with the embodiment shown in FIG. 1 . Major features include an injection gas supply line 80 (with the associated features previously described), a conduit 100 (likewise with the associated features previously described) and the generally spherical intermediate chamber 120 .
In the embodiment illustrated in FIG. 2, a compressor (not shown) provides fluid to the fluid jet tube 200 at conveniently from about 2 to about 1,000 times the ambient pressure of the sea floor that being mined. The fluid from the fluid jet tube 200 disaggregates the strata on the sea floor. As mentioned previously, the strata comprise the hydrocarbon-containing clathrate and sediment. The hydrocarbon-containing clathrate is largely hydrocarbon and water. Also as previously described, the hydrocarbon is mostly methane, propane, isopropane, butane, isobutane, pentane and isomers of pentane. The currents generated by the fluid from the fluid jet tube 200 sweep the clathrate rich portion toward the opening 108 in the generally cylindrical lower conduit segment 104 .
The injection gas supply line 80 is opened either a short time after or before or at the same time as the fluid jet tube 200 begins operation. Injection gas performs the same function in the same way as described above regarding FIG. 1, wherein it aids in transporting comminuted fragments of the cathrate and sediment from the strata upward (toward the sea surface). In this embodiment, decomposition of the clathrate, separation from sediment and collection of hydrocarbon gas is the same as previously described.
The two described embodiments (one using a rotary tilling drum, and the other using a fluid jet tube) are examples of how the principles of the invention apply in two different types of continuous mining applications. Other continuous mining applications capable of disrupting clathrate rich strata on the sea floor are known to those skilled in the art of continuous mining. Such other continuous mining applications as are suited to the principles of the invention are intended to fall within the scope of the appended claims.
From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications are intended to be within the scope of the following claims.
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A method and apparatus for mining of hydrocarbons from a hydrocarbon-containing clathrate such as is found on the ocean floor. The hydrocarbon containing clathrate is disaggregated from sediment by first disrupting clathrate-containing strata using continuous mining means such as a rotary tilling drum, a fluid injector, or a drill. The clathrate-rich portion of sediment thus disrupted from the sea floor strata are carried through the apparatus to regions of relative lower pressure and/or relative higher temperature where the clathrate further dissociates into component hydrocarbons and water. The hydrocarbon is recovered with the assistance of a gas that is injected and buoys the hydrocarbon containing clathrate helping it to rise to regions of lower pressure and temperature where hydrocarbon is released. The sediment separated from the hydrocarbon returns to the ocean floor.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. Utility application Ser. No. 13/486,607, filed on Jun. 1, 2012, now pending. U.S. Utility application Ser. No. 13/486,607 is a divisional application of U.S. Utility application Ser. No. 11/691,450, filed on Mar. 26, 2007, issued as U.S. Pat. No. 8,205,717 on Jun. 26, 2012. U.S. Utility application Ser. No. 11/691,450 claims benefit of U.S. Provisional Application No. 60/743,778, filed on Mar. 25, 2006. This application claims benefit of U.S. Utility application Ser. Nos. 13/486,607 and 11/691,450 and U.S. Provisional Application No. 60/743,778. U.S. Utility application Ser. Nos. 13/486,607 and 11/691,450, and U.S. Provisional Patent Application No. 60/743,778 are incorporated by reference in their entirety for all purposes as if fully set forth herein.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING
[0003] Not applicable.
BACKGROUND OF THE EMBODIMENTS
[0004] 1. Field of Embodiments
[0005] The field of the embodiments of the Vehicle Ladder Mounting System for Custom Installations generally involves the support of objects on top of vehicles and more specifically the support of ladders on vehicles.
[0006] 2. Description of Prior Art
[0007] The prior art involves the support means mounted to the bed, top or sides of vans, pickup or utility trucks for ladders. The support means can be as rudimentary as a bracket mounted to the truck in which the ladder rests on the truck. The support means can also comprise a metal frame installed onto the truck bed or top of a van.
[0008] There are many drawbacks to the current state of the art in ladder support devices. Most significantly, current inventions do not allow for the ability to easily guide a ladder onto and off of a preexisting vehicle ladder rack or roof rack and preventing the ladder from shifting as the vehicle is in motion. The current state of the art does not allow for a wide variety of configurations for accepting varying types of ladders. Further, current inventions do not allow for the easy attachment of guide rails to the support devices. The embodiments of the Vehicle Ladder Mounting System for Custom Installations addresses these concerns.
BRIEF SUMMARY OF THE EMBODIMENTS
[0009] Embodiments of the Vehicle Ladder Mounting System, are comprised of a guide rail assembly, a plurality of support assemblies and one or more end accepting means. The guide rail assembly of the embodiments of the Vehicle Ladder Mounting System for Custom Installations is comprised of two parallel or near parallel (angled) guide rails connected by a one or more end accepting means, at one or both ends of the guide rails. Or in other words, the Vehicle Ladder Mounting System for Custom Installations is comprised of one or more end accepting means, at one or both ends of the guide rails and also may be connected by a plurality of interior cross-member assemblies.” The embodiments of the Vehicle Ladder Mounting System for Custom Installations also comprises a guide rail design that allows for a wide variety of configurations to be made due to the plurality of square channels formed by the guide rails. The guide rails allow for flexible installation on a variety of surfaces and vehicles. The guide rails in particular allow for highly flexible assembly of a variety of configurations. The embodiments of the Vehicle Ladder Mounting System for Custom Installations can be easily adapted, augmented, and modified because of the structure of the aluminum channel. The design of the embodiments of the Vehicle Ladder Mounting System for Custom Installations allows for multiple configurations as the guide rail can be attached to a pre-existing cross-member in many configurations via a clamping or bolt-nut combination. Therefore, due to the flexibility of the rails nearly limitless configurations can be constructed.
[0010] This description, and the detailed description below, is not intended to limit the number of configurations of the embodiments of the Vehicle Ladder Mounting System for Custom Installations as the system to make these easily configurable arrangements is the embodiments of the Vehicle Ladder Mounting System for Custom Installations described herein, not merely the various configurations posed as examples.
[0011] One embodiment of the Vehicle Ladder Mounting System for Custom Installations is comprised of a clamping system which allows the Vehicle Ladder Mounting System to be mounted to any pre-existing ladder or roof rack made for vehicles by means of clamping to the racks cross-members by using a universal mounting clamp comprised of two clamping plates.
[0012] Depending on the application requirements of the embodiments of the Vehicle Ladder Mounting System for Custom Installations, various configurations of the guide rail systems can be attained to meet specific shape of the ladder to be carried on the user's ladder or roof rack. This is done by adjusting the guide rails to be parallel and spaced apart to a specified width, thus fitting the user's specific extension ladder.
[0013] There has thus been outlined, rather broadly, the more important features of the embodiments of the Vehicle Ladder Mounting System for Custom Installations in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the embodiments that will be described hereinafter and which will form the subject matter of the claims appended hereto.
[0014] In this respect, before explaining at least one embodiment of the Vehicle Ladder Mounting System for Custom Installations in detail, it is to be understood that the embodiment is not limited in this application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The embodiment or embodiments are capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be used as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the embodiments. Additional benefits and advantages of the embodiments will become apparent in those skilled in the art to which the present embodiments relates from the subsequent description of the preferred embodiment and the appended claims, taken in conjunction with the accompanying drawings. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the embodiments.
[0015] Further, the purpose of the foregoing abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientist, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the embodiments of the application which is measured by the claims, nor is it intended to be limiting as to the scope of the embodiments in any way.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS OF THE EMBODIMENTS
[0016] FIG. 1 is a perspective view of one embodiment of the guide rail used in the guide rail assembly. This figure also illustrates how a plurality bolts can be inserted into and arranged along the channels of the rails.
[0017] FIG. 2 illustrates a cross-sectional view illustrating the attachment of a guide rail to any pre-existing cross-member by bolting directly through the cross-member.
[0018] FIG. 3A shows the shows the polymeric pad installed into a guide rail; FIG. 3B shows the installation of a polymeric pad into a guide rail and shows how the male slot formed by the polymeric pad is accepted by the female slot of a guide rail embodiment.
[0019] FIG. 4A is a perspective view of an embodiment of the vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the parallel position showing interior cross-member supports (cradles); FIG. 4B is a side view of an embodiment of a vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the parallel position.
[0020] FIG. 5A is a perspective view of an embodiment of the vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the parallel position; FIG. 5B is a side view of an embodiment of a vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the parallel position.
[0021] FIG. 6A is a perspective view of an embodiment of the vehicle ladder mounting system showing the acceptance of a step ladder into the guide rails; FIG. 6B is a side view of an embodiment of the vehicle ladder mounting system showing the acceptance of an extension ladder into the guide rails.
[0022] FIG. 7A is a perspective view of an embodiment of the vehicle ladder mounting system showing the acceptance of a step ladder into the guide rails; FIG. 7B is a side view of an embodiment of the vehicle ladder mounting system showing the acceptance of a step ladder into the guide rails.
[0023] FIG. 8A is a perspective view of an embodiment of a vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the nearly parallel (angled) position showing interior cross-member supports (cradles); FIG. 8B is top view of an embodiment of the vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the nearly parallel (angled) position; FIG. 8C is side view of an embodiment of the vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the nearly parallel (angled) position.
[0024] FIG. 9A is a perspective view of an embodiment of a vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the nearly parallel (angled) position; FIG. 9B is top view of an embodiment of the vehicle ladder mounting system showing the attachment to pre-existing cross-members with the guide rails in the nearly parallel (angled) position; FIG. 9C is side view of an embodiment of the vehicle ladder mounting system.
[0025] FIG. 10A is a front view of an embodiment of the vehicle ladder mounting system showing how the universal mounting clamp engages a round cross-member; FIG. 10B is a perspective view of an embodiment of the vehicle ladder mounting system showing how the universal mounting clamp engages a round cross-member; FIG. 10C is a front view of an embodiment of the vehicle ladder mounting system showing how the universal mounting clamp engages a square cross-member; FIG. 10D is a perspective view of an embodiment of the vehicle ladder mounting system showing how the universal mounting clamp engages a square cross-member; FIG. 10E is a front view of an embodiment of the vehicle ladder mounting system showing how the universal mounting clamp engages a rectangular cross-member; FIG. 10F is a perspective view of an embodiment of the vehicle ladder mounting system showing how the universal mounting clamp engages a rectangular cross-member.
[0026] FIG. 11A is a perspective view of an embodiment of the vehicle ladder mounting system showing an end accepting means, a roller end cap, terminating an end of the vehicle ladder mounting system; FIG. 11B is a side view of an embodiment of the vehicle ladder mounting system showing an end accepting means, a roller end cap, terminating an end of the vehicle ladder mounting system.
[0027] FIG. 12A is a perspective view of an embodiment of the vehicle ladder mounting system showing an end accepting means, an aluminum and/or polymeric end cap, terminating an end of the vehicle ladder mounting system along with an aluminum and/or polymeric edge guard on the vertical wall of the guide rail; FIG. 12B is a side view of an embodiment of the vehicle ladder mounting system showing an end accepting means, an aluminum and/or polymeric end cap, terminating an end of the vehicle ladder mounting system along with an aluminum and/or polymeric edge guard on the vertical wall of the guide rail; FIG. 12C is a side view of an embodiment of the vehicle ladder mounting system showing an end accepting means, an aluminum and/or polymeric end cap, terminating an end of the vehicle ladder mounting system along with an aluminum and/or polymeric edge guard on the vertical wall of the guide rail.
[0028] FIG. 13A is a perspective view of an embodiment of the vehicle ladder mounting system showing a polymeric slip pad engaged on both the vertical and horizontal interior walls of the guide rail; FIG. 13B is a side view of an embodiment of the vehicle ladder mounting system showing a polymeric slip pad being engaged on either or both the vertical and horizontal interior walls of the guide rail.
[0029] FIG. 14A is a perspective view of an embodiment of the vehicle ladder mounting system showing the end of a guide rail where an alternative aluminum and/or polymeric edge guard engaged in a guide rail; FIG. 14B is the opposite perspective view of an embodiment of the vehicle ladder mounting system showing the end of a guide rail where an alternative aluminum and/or polymeric edge guard engaged in a guide rail.
[0030] FIG. 15A is a top view of an embodiment of the vehicle ladder mounting system without pre-existing or interior cross-members showing a ladder rack in an orientation for accepting an extension ladder with the guide rails in the parallel position allowing the guide rails to be adjusted to fit the width of the ladder along with the adjustable end accepting means; FIG. 15B is a top view of an embodiment of the vehicle ladder mounting system without pre-existing cross-members or interior cross-members showing a ladder rack in an orientation for accepting a step ladder with the guide rails in the nearly parallel (angled) position allowing the guide rails to be adjusted to fit the width of the ladder along with the adjustable end accepting means.
[0031] FIG. 16A is a top view of an embodiment of the vehicle ladder mounting system showing a ladder rack affixed to pre-existing cross-members but without interior cross-members showing a ladder rack in an orientation for accepting an extension ladder with the guide rails in the parallel position allowing the guide rails to be adjusted to fit the width of the ladder along with the adjustable end accepting means; FIG. 16B is a side view of an embodiment of the vehicle ladder mounting system showing a ladder rack affixed to pre-existing cross-members but without interior cross-members showing a ladder rack in an orientation for accepting an extension ladder with the guide rails in the parallel position allowing the guide rails to be adjusted to fit the width of the ladder along with the adjustable end accepting means.
[0032] FIG. 17 is a perspective view of an embodiment of the vehicle ladder mounting system shown on a pre-existing roof rack on an SUV with interior cross-members with the guide rails in the nearly parallel (angled) position to accept a step ladder along with fixed end accepting means on both ends of the guide rails.
[0033] FIG. 18A is a perspective cross-sectional view of an embodiment of the vehicle ladder mounting system showing an interior cross-member attaching to a guide rail along with the polymeric pad on top of the interior cross-member. The interior cross-member supports (cradles) the ladder as it slides along the guide rails and affixes the two guide rails together. FIG. 18B is a cross-sectional side view of an embodiment of the vehicle ladder mounting system showing an interior cross-member attaching to a guide rail along with the polymeric pad on top of the interior cross-member. The interior cross-member supports (cradles) the ladder as it slides along the guide rails and affixes the two guide rails together.
[0034] FIG. 19A is a front view of an embodiment of the vehicle ladder mounting system showing how the universal mounting clamp can be adjusted to accommodate various widths of ladders by adjusting the guide rails closer together or further apart; FIG. 19B is a front view of an embodiment of the vehicle ladder mounting system showing how the guide rails can be fixed at a specific width using interior cross-members.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0035] The embodiments of the Vehicle Ladder Mounting System for Custom Installations (hereinafter “Ladder Mounting System”) 100 are comprised of two guide rails 101 along with one or more end accepting means 1101 and or 1201 connected to a plurality of cross-members 401 . The cross-members 401 are pre-existing on the vehicle or provided by the user. A rail 101 is broadly defined as a long, narrow member that can be fabricated with a variety of cross sections and from a variety of metallic materials. In a preferred embodiment, the guide rails 101 are manufactured of aluminum. In a preferred embodiment, the rail 101 is comprised of an “L” shaped cross-section. The two interior surfaces of the “L” shaped cross-section form a right or ninety degree (90°) angle. The two exterior surfaces of the “L” shape form a reflex angle of two-hundred and seventy degrees (270°). See FIGS. 1 , 2 , and 3 .
[0036] In another preferred embodiment of the Ladder Mounting System, each exterior surface forms “T” shaped bolt sub-channels 103 (see FIG. 1 ) for a total see FIG. 2 ). This preferred embodiment is termed the guide rail 103 . The guide rail embodiment allows for flexibility in constructing the Ladder Mounting System specific to the user's needs. By sliding bolts 102 along the channels (see FIG. 1 ) the location of the bolts 102 along the channels can be adjusted and unique, custom configurations of guide rail assemblies can be formed. The guide rail embodiment also allows for different mounting options for adding onto ladder racks from other manufacturers and for user-supplied supports.
[0037] In a preferred embodiment of the Ladder Mounting System, the guide rail 101 is comprised of smaller sub-channels that run the length of the guide rail. The two interior surfaces each form a small “T” shaped sub-channel 104 that runs the length of the guide rail. See FIG. 1 . The exterior surfaces each form “T” shaped bolt sub-channels 103 that run the length of the guide rail. See FIG. 1 . The interior walls of the guide rail 101 , or those walls that form a right angle, are smooth and rigid to aid the smooth loading of a ladder onto the embodiments of the Ladder Mounting System.
[0038] In another preferred embodiment of the Ladder Mounting System, the small “T” shaped sub-channel 104 that runs the length of the rail can accept corresponding slots, grooves or channels of accessories including, but not limited to, a polymeric slip pad.
[0039] The “T” shaped bolt sub-channels 103 that run the length of the guide rail can accept the head of a bolt. The bolt may slide along the length of the guide rail in the “T” shaped bolt sub-channels. The head of the bolt is incapable of being removed from the square channel except at the ends of the square channels located at the end of the guide rails. See FIGS. 1 and 2 . The “T” shaped bolt sub-channels 103 can accept the head of a bolt by sliding the bolt head from either end of the channel. Most importantly, the “T” shaped bolt sub-channels 103 do not allow the bolt to turn as the width of the channel is only slightly larger than the size of the bolt to allow the bolt to slide along the length of the guide rail 101 , but not allow the bolt to turn. The “T” shaped bolt sub-channels 103 do not allow the bolt head to move perpendicularly to the aluminum channel as the bolt head is restrained by small channel.
[0040] Other embodiments of the Ladder Mounting System are comprised of a guide rail assembly that can be mounted to a tubular or solid cross-member 401 by means of clamping using such as the universal mounting clamps 402 . The universal mounting clamps 402 can be affixed to a cross-member 401 with a wide variety of cross-sectional shapes. See FIG. 8 .
[0041] In addition, other embodiments of the Ladder Mounting System are comprised of fasteners connecting through the guide rails directly to the cross-member 401 . A rail 101 can be secured to any object 203 , including cross-members 401 that are user supplied, that can accept a bolt through the object. As illustrated in FIG. 2 , bolts 201 can be inserted into channels at appropriate location and affixed to the object to which the guide rail is to be secured. The bolts are then passed through the holes in the object 203 and secured with nuts 202 .
[0042] Other embodiments of the Ladder Mounting System 100 are comprised of one or more interior cross-members 1701 and one or more longitudinal members 1702 . The interior cross-members 1701 and the longitudinal members 1702 are capable of accepting non-slip pads. The interior cross-members 1701 extend horizontally from one rail to the other rail anywhere in the middle of the rail assembly. The longitudinal members 1702 extend from one interior cross-members 1701 to another interior cross-members 1701 . The combination of two interior cross-members 1701 and at least one longitudinal members 1702 create a basket for accepting ladders preventing the ladder from falling through embodiments of the Ladder Mounting System. In addition, interior cross-members 1701 provide extra lateral support for embodiments of the Ladder Mounting System.
[0043] Other embodiments of the Ladder Mounting System 100 comprise an end accepting means. The end accepting means is any device that allows for easy insertion and removal of a ladder into and from the embodiments of the Ladder Mounting System. An end accepting means includes a roller end cap 1101 . See FIG. 9A and FIG. 9B . An end accepting means also includes an aluminum and/or polymeric end cap 1201 . See FIG. 10A and FIG. 10B . Both the roller end cap 1101 and the polymeric end cap 1201 . Rollers 1201 can be added to the channels 101 in a manner similar to accessories. Bolts 102 are positioned at the appropriate location along the square or rectangular channels formed by the guide rail, typically at the end of the guide rail 101 for installation of a roller 1201 . The bolts 102 are inserted through holes in the roller 1201 , and the bolts are secured by nuts 202 . The rollers 1201 permit easy load-on and load-off of the ladders onto the ladder rack system 100 .
[0044] Polymeric slip pads 301 may be installed onto the channels 101 at locations that aid the loading of ladders. The polymeric slip pads 301 form channels and grooves that accept the appropriate channel and grooves on the guide rails. See FIG. 11 . The polymeric slip pads 301 may be installed onto a channel 101 and accept the channels and ridges on the channel 101 . The polymeric slip pads can be inserted onto a channel 101 and provide a non-stick surface that allows ladders to more easily slide along the channels 101 .
[0045] The Ladder Mount System 100 can be secured to preexisting or add-on roof rack, luggage rack, ladder rack or any type rack. The Ladder Mounting System 100 can be mounted to a tubular or solid cross-member 401 by means of a clamping means or fastening means through the cross-member 401 using a universal mounting clamp. The Ladder Mounting System 100 is comprised of an end-accepting means 403 . The end-accepting means 403 includes an adjustable or fixed roller or loading pad that extends from one rail to the other rail and allows for easier loading or unloading of the ladder.
[0046] Other embodiments of the Ladder Mounting System 100 are comprised of adjustable guide rails that make up the Ladder Mounting System that can be adjusted in width apart from each other which allows for storage of different sizes of ladders.
[0047] Other embodiments of the Ladder Mounting System 100 are comprised of guide rails that make up the Ladder Mounting System can be adjusted from parallel to nearly parallel (angled) to fit the sloped sides of a step ladder.
[0048] Other embodiments of the Ladder Mounting System 100 are comprised of an interior cross-member 1701 capable of accepting non-slip pads and extending horizontally from one rail to the other rail anywhere in the middle of the guide rails which would affix the guide rails creating a cradle for accepting ladders and where the guide rails could be either parallel or nearly parallel (angled).
[0049] Other embodiments of the Ladder Mounting System 100 are of polymeric cross-member pads 1801 that clip over an interior cross-member 1701 help for an interior piece that will help cradle the ladder. The vehicle ladder mounting system described are comprised of an aluminum and/or polymeric edge guard 1401 that can be attached to the ends of the guide rails that helps guide the ladder along the guide rails and protects from interference between the ends of the guide rails and the ladder. In other embodiments of the Ladder Mounting System 100 all components except fasteners are manufactured from polymeric materials, reinforced polymeric materials, or composite polymeric materials.
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The Vehicle Ladder Mounting System is comprised of two parallel or nearly parallel (angled) guide rails and one or two end accepting means. The embodiments of the Ladder Mounting System can be easily adapted, augmented, and modified because of the structure of the guide rails (or aluminum channels in the guide rails). The vehicle ladder mounting system can be mounted to a tubular or solid cross-member by a clamping means using a universal mounting clamp. The design of the embodiments of the Ladder Mounting System allows for multiple configurations as the guide rails can be adjusted to fit the width and/or angle of the ladder. The design of the embodiments of the Ladder Mounting System allows the width and/or angle to be fixed by means of the use of interior cross-member assemblies thus forming a cradle to support the ladder.
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CROSS-REFERENCE TO RELATED APPLICATION
The application claims the benefit, under 35 U.S.C. §119(e), of U.S. Provisional Application Ser. No. 60/807,217 filed Jul. 13, 2006, the contents of which are incorporated herein by reference.
ORIGIN OF THE INVENTION
The invention described herein was made in the performance of work under a NASA contract and by employees of the United States Government and is subject to the provisions of Public Law 96-517 (35 U.S.C. §202) and may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties thereon or therefor. In accordance with 35 U.S.C. §202, the contractor elected not to retain title.
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to thermocouples and in particular to the thermocouple designs capable of self validation.
BACKGROUND OF THE INVENTION
The basic concept of a sensor automatically monitoring its operational capability, i.e., self-validating performance, is generally recognized. An attempt is made to continuously monitor and self-validate the sensor's performance to determine the health of the sensor. The process of self-validation involves the continued assessment of a combination of: 1) reviewing physical parameters obtained real-time by means of electronic circuitry to obtain actual measurement data; and 2) utilizing a combination of statistical tools to estimate and predict a measurement value at a given time in the process and compare the predicted measurement value to the actual measurement data. Self-validation processes used by others include ARMA (Auto Regression Moving Average), LCSR (Loop Current Step Response), and Power Spectrum Density determination. The failure or success of any of these processes presupposes properly functioning sensor circuitry.
However, in many sensors, and particular thermocouples, the actual cause for failure is directly related to the physical bonding between the thermocouple sensor element and the attachment surface. As a consequence, conventional self-validating techniques may fail to reliably identify the bonded/debonded condition that directly leads to sensor failure.
For the reasons stated above, and for other reasons that will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternative approaches to thermocouple validation.
SUMMARY OF THE INVENTION
The various embodiments provide a Self-Validating Thermocouple (SVT) System capable of detecting sensor probe open circuits, short circuits, and unnoticeable faults such as a probe debonding and probe degradation. The various embodiments provide such capabilities by incorporating a heating or excitation element into the measuring junction of the thermocouple. By heating the measuring junction and observing the decay time for the detected DC voltage signal, it is possible to indicate whether the thermocouple is bonded or debonded. A change in the thermal transfer function of the thermocouple system causes a change in the decay time for the DC voltage signal. The various embodiments are further capable of traditional validation procedures as the excitation elements in accordance with the various embodiments do not interfere with the normal operation of the thermocouple.
The invention includes methods and apparatus of varying scope.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic of a basic thermocouple design.
FIGS. 2A and 2B depict portions of two thermocouple circuits having measuring junction excitation elements for use with the various embodiments.
FIG. 3 is a block schematic of a thermocouple system in accordance with an embodiment of the invention.
FIG. 4 is a flowchart of a method of validation in accordance with one embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the inventions may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that process, mechanical, and electrical changes may be made without departing from the spirit and scope of the present invention. It is noted that the drawings are not to scale unless a scale is provided thereon. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims and equivalents thereof.
It is well known that a metal or other conductor subjected to a thermal gradient will generate a voltage. To measure the voltage, a closed circuit must be provided, thus requiring a return conductor. If the same material were used for the return conductor, its temperature-generated voltage would cancel out the voltage of the first conductor. However, the voltage response is dependent upon the conductor itself. By using a dissimilar metal for the return conductor, a measurable voltage differential will be developed that is related to the temperature gradient experienced by both conductors.
FIG. 1 is a schematic of a basic thermocouple design. The thermocouple 100 includes a first conductor 102 and second conductor 104 . Two junctions 106 and 108 are formed where the two conductors are joined, and the voltage differential can be read across nodes 110 and 112 . One junction, such as junction 106 , is a measuring junction while the remaining junction, such as junction 108 , is the reference junction.
The various embodiments include a heating or excitation element at the measuring junction. FIGS. 2A and 2B depict portions of two thermocouple circuits 200 A and 200 B having measuring junction excitation elements for use with the various embodiments. In FIG. 2A , the thermocouple 200 A includes a first capacitor 220 , a resistor 222 and a second capacitor 224 coupled in series at the measuring junction 206 . The thermocouple 200 A further includes a first inductor 228 and a second inductor 230 coupled in series with the measuring junction 206 . The resistor 222 acts as an excitation element. Elements located above the dashed line in FIG. 2A may generally be located on a circuit board of a thermocouple system while elements below the dashed line would be located at the sensing element. The excitation element 222 is in thermal contact with the measuring junction 206 . That is, the excitation element 222 is sufficiently coupled to the measuring junction to cause a temperature rise in the measuring junction 206 upon application of the alternating current (AC) stimulation signal. The excitation element 222 need not be in physical contact, and may be separated by a thermal compound capable of thermal transfer.
By applying an AC signal from the excitation and signal conditioning circuitry 226 , such as a pulse width modulated signal, to resistor 222 the measuring junction 206 will heat up. The AC stimulation signal, by itself, does not affect the thermocouple measuring junction 206 because inductors 228 and 230 act as an open circuit to the AC signal. In a similar manner, the DC voltage generated by the thermocouple will not affect the resistor 222 voltage since the capacitors 220 and 224 act as an open circuit to the DC signal. While two capacitors 220 and 224 and two inductors 228 and 230 are depicted in the embodiment of FIG. 2A , one capacitor and one inductor would suffice in that the path to the excitation element 222 could still act as an open circuit to a DC signal with one capacitor in the loop to the excitation and signal conditioning circuitry 226 and the path to the measuring junction 206 could still act as an open circuit to an AC signal with one inductor in the loop to the excitation and signal conditioning circuitry 226 . Other circuit configurations can also be used to satisfy these criteria. For one embodiment, the same lead could be used to supply the AC signal to the resistor 222 and to read the measuring junction 206 . For example, capacitor 220 and inductor 228 could both be coupled to a single lead in the excitation and signal conditioning circuitry 226 , and capacitor 224 and inductor 230 could both be coupled to a single lead in the excitation and signal conditioning circuitry 226 such that a circuit path containing the resistor 222 would be coupled in parallel with a circuit path containing the measuring junction 206 .
In FIG. 2B , the thermocouple 200 B includes one inductor 228 coupled in parallel with series-coupled capacitor 220 and resistor 222 between the excitation and signal conditioning circuitry 226 and the measuring junction 206 . The resistor 222 acts as an excitation element. Elements located above the dashed line in FIG. 2B may generally be located on a circuit board of a thermocouple system while elements below the dashed line would be located at the sensing element. The excitation element 222 is in thermal contact with the measuring junction 206 . The excitation element 222 need not be in physical contact, and may be separated by a thermal compound capable of thermal transfer. For a further embodiment, the same lead could be used to supply the AC signal to the resistor 222 and to read the measuring junction 206 . For example, capacitor 220 and inductor 228 could both be coupled to a single lead in the excitation and signal conditioning circuitry 226 such that a circuit path containing the resistor 222 would be coupled in parallel with at least a portion of a circuit path containing the measuring junction 206 .
By applying an alternating current (AC) signal, such as a pulse width modulated signal, to resistor 222 the measuring junction 206 will heat up. The AC stimulation signal, by itself, does not affect the thermocouple measuring junction 206 . In a similar manner, the DC voltage generated by the thermocouple will not affect the resistor 222 voltage since the capacitor 220 acts as an open circuit to the DC signal. Other designs may be utilized with the various embodiments, provided that the resulting excitation element provides one path inhibiting an AC signal and another path providing an open circuit to a DC signal. The embodiment of FIG. 2A adds improved noise immunity to the thermocouple circuit using a four-wire configuration while the embodiment of FIG. 2B reduces physical interfacing by using a three-wire configuration. As shown in FIG. 2B , a circuit path containing the resistor 222 may also include the measuring junction 206 .
Thermocouples including excitation elements in accordance with embodiments of the invention are compatible with traditional thermocouple systems. Typical systems would provide instrumentation such as a cold junction compensator, signal conditioner circuitry, analog/digital (A/D) converter, processor, power section, and system interface, e.g., a universal serial bus (USB) interface or the like. However, the various embodiments would further include thermocouple excitation means and a pulse wave modulator (PWM).
FIG. 3 is a block schematic of a thermocouple system 350 in accordance with an embodiment of the invention. The thermocouple system includes a measuring junction 306 and reference junction 308 . The measuring junction 306 includes an excitation element 322 in accordance with an embodiment of the invention. The excitation element 322 is coupled to receive an AC stimulation signal from PWM 354 through excitation circuitry 352 . A cold junction compensator 356 and signal conditioner circuit 358 are coupled to receive the detected DC signal from the measuring junction 306 . An A/D converter 360 is coupled to receive the compensated and conditioned signal and provide a digital signal representative of the expected temperature of the measuring junction 306 to the processor 362 . Interface (I/F) 364 is coupled to the processor 362 to provide input/output (I/O) capabilities to receive commands at the processor 362 to perform various validation methods in accordance with the embodiments, and to provide data output of the detected temperature and of detected health of the system 350 . Power section 366 may provide power to the various elements of the system 350 . Alternatively, power may be received through the I/F 364 .
A memory 368 may be included to store historical data on rise and/or decay times of the DC signal of the measuring junction 306 during validation. Preferably, the memory 368 is a non-volatile memory, such as flash memory or EEPROM (electrically erasable programmable read-only memory), so that historical data is retained in case of a power failure.
During operation of a self-validating thermocouple in accordance with the various embodiments, the following occurs.
Temperature measurement: The A/D converter measures the very small (μV to mV) voltage of the thermocouple and the cold junction compensators. Since the output voltage of the thermocouple is between μV and mV, it is generally necessary to use the internal gain of the A/D converter. The A/D converter also monitors the output of the cold junction compensator. Depending on the type of thermocouple used, the processor compensates the thermocouple output to obtain an accurate reading as is well understood in the art. The temperature may be calculated by using the following equation: Ttip=A 0 +A 1 Vout+A 2 Vout 2 + . . . +AnVout n . Alternatively, the temperature could be generated from a look-up table. Software in processor 362 can assist the user to operate in learning mode to automatically gather historical data of the thermocouple system during operation (monitoring and diagnostic mode). The user can also manually enter historical data.
Thermocouple Validation: To observe if the thermocouple is short or open, each differential line of the thermocouple is measured as being single ended to estimate the common mode. The leakage resistance of the capacitors of the AC-coupled PWM will either pull high or low any lead as the result of an open circuit. This condition can be detected by the processor, which then flags the condition as one of the failure modes. The thermocouple is slightly biased to have a common mode offset, which will change in the case of a short circuit. This condition can also be detected by the processor and flagged as another failure mode.
Bonding/Debonding Detection: Debonding of the thermocouple is evaluated based on a departure from a known thermal transfer function of the bonded system. When debonding occurs, the reduction in thermal mass translates into a different temperature rate of change, resulting in different rise and decay times. The processor sends a PWM excitation signal for the length of time needed to heat up the thermocouple. The difference in temperature (d[temp]/dt) and the time it takes to return to the original temperature before the excitation of the thermocouple indicates the health of the thermocouple and whether the thermocouple is bonded or debonded. For example, the thermocouple in a bonded condition will have faster decay in temperature, and thus detected DC voltage, than if it were in an unbonded condition. In addition, historical values of the rise and decay times can be compared with current values to indicate degradation of the thermocouple.
An operator may commence operation by selecting to start a diagnosis/monitoring sequence, wherein the PWM is used to estimate the time constants corresponding to the correct configuration. The user has the further option of using previous diagnostic values, which are stored in memory and readily available upon each commencement of operation.
FIG. 4 is a flowchart of a method of validation in accordance with one embodiment of the invention. The method of FIG. 4 may be initiated by an operator request, or the processor of the thermocouple system may be configured to periodically initiate the validation method, such as daily, weekly, or monthly. At 480 , an AC excitation signal is applied to the thermocouple. At 482 , the rise time and/or decay time of the DC signal of the thermocouple are observed. A thermocouple that is bonded to an object of interest, i.e., the object whose temperature is desired to be measured, will exhibit differing rise and decay times of its DC signal during and after, respectively, AC excitation. Optionally, the rise and/or decay times can be compared to historical data at 484 . Historical comparisons can be especially useful in detecting degradation of the thermocouple measuring junction where trends in the times can be observed. Values that are trending in one direction or the other, as opposed to random variation, can be indicative of degradation of the thermocouple. This failure mode may be used to indicate a need for calibration, repair, or replacement.
If the raw observations for rise and/or decay times at 482 , of the trend observations at 484 , indicate a failure at 486 , the resulting failure mode may be transmitted to the user or host system at 488 . If no failure is indicated at 486 , the validation may end at 490 .
The Self-Validating Thermocouple (SVT) System in accordance with the various embodiments not only facilitate detection of open or short faults, but also facilitates identification of degradation of the thermocouple as well as its bonded or debonded state. The SVT system may provide signal conditioning and data acquisition capability in-situ to each thermocouple. It is capable of interfacing and processing signals from the most commonly used thermocouple types (J, K, E, and T) as well as other thermocouple types. The SVT can periodically evaluate the health of the thermocouple and the measurement capability. The circuit is capable of detecting failures and notifying the user/operator of the failure mode. The SVT may automatically provide a stream of data to be analyzed, or the SVT may respond to individual requests at any time, i.e., on demand.
SVTs in accordance with the various embodiments will be valuable for anyone using thermocouples as temperature sensors that require highly reliable measurements. The invention could allow elimination of the need for redundant thermocouple measurements which, in turn, translates into savings in operating and maintenance costs. Finally, the present invention facilitates increased failure detection capabilities as well as improved dating validity and reliability.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the embodiments shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
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Self-Validating Thermocouple (SVT) Systems capable of detecting sensor probe open circuits, short circuits, and unnoticeable faults such as a probe debonding and probe degradation are useful in the measurement of temperatures. SVT Systems provide such capabilities by incorporating a heating or excitation element into the measuring junction of the thermocouple. By heating the measuring junction and observing the decay time for the detected DC voltage signal, it is possible to indicate whether the thermocouple is bonded or debonded. A change in the thermal transfer function of the thermocouple system causes a change in the rise and decay times of the thermocouple output. Incorporation of the excitation element does not interfere with normal thermocouple operation, thus further allowing traditional validation procedures as well.
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[0001] This application claims the priority benefit under 35 U.S.C. section 119 of U.S. Provisional Patent Application No. 61/857,970 entitled “Trailer Jack Stand Support” filed on Jul. 24, 2013; which is in its entirety herein incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a device for stabilizing a trailer jack on hard or soft ground after the trailer has been disconnected from its towing vehicle, and more particularly to a stabilizing device that can receive a wheel, a jack pad or the shaft of a jack. The present invention also relates to a safety stand of substantially fixed height of such character that it can be used to support house trailers when they are parked, the drawbar end of trailers in general or, in fact, any relatively stationary and appreciably heavy weight which needs a relatively stable support.
BACKGROUND OF INVENTION
[0003] Various stands have been available ranging from mere blocks of wood or concrete to somewhat complicated adjustable stands which can be elevated and lowered by employment of a crank with a rack and pinion. Blocks are not always acceptable because of their weight and bulk, especially when it might be advantageous to move them together with the vehicle. Adjustable-type stands often are not stable enough to be dependable and, when constructed in a stable fashion, are frequently unnecessarily expensive. They also have the disadvantage of not being readily stowed.
[0004] In setting up a mobile home trailer, a manufactured building or other similar structures and objects, the structure must be blocked and supported. One simple method employed for blocking the structure is to use a plurality of concrete blocks stacked up on top of each other. As each concrete block has a limited footprint, each block stack has a limited weight capacity with respect to the ground. Therefore, in order to support modern structures, wherein several thousand pounds must typically be supported, two or more side by side block stacks must be established. Not only is a series of concrete block stacks aesthetically unpleasant, the need to bring a large number of concrete blocks to the job sight is expensive and labor intensive. Additionally, a relatively high concrete block stack may tend to be unstable under various loads and environmental conditions.
[0005] In order to overcome the problems of using only concrete blocks to support a structure various devices have been proposed. Such devices, although working with varying degrees of efficiency, tend to be difficult to use and maintain and are unduly heavy ad bulky.
[0006] Therefore, there is a need in the art for a structure support stand that addresses the above-stated problems in the art. Such a device must be capable of supporting several thousand pounds and must not be an eye sore. Such a device must be relatively lightweight and easy to transport, assemble and use. Ideally, such a device will be relatively inexpensive to manufacture and maintain.
OBJECTS OF THE INVENTION
[0007] A primary object of the present invention is to provide a new and improved jack stand for supporting stationary vehicles and other weights which is very rugged in its construction, and simple in its assembly and or construction.
[0008] Another object of the invention is to provide a new and improved stand for supporting vehicles and comparable loads, parts of which are uniform and interchangeable, and, which though particularly rugged, has a structural arrangement permitting it to be relatively light in weight compared to the amount of load it is capable of carrying.
[0009] Still another object of the invention is to provide a new and improved stand for supporting stationary loads which besides being stable in a position for one selected height, can be shifted to accommodate a different selected height without sacrificing its rugged stability.
[0010] Still another object of the supporting is to provide a new and improved stand for supporting stationary loads which is relatively simple and inexpensive not only to manufacture and is build in such a way that it occupies a relatively compact space.
[0011] With these and other objects in view, the invention consists in the construction, arrangement, and combination of the various parts of the device, whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings.
[0012] To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of the appended claims.
BRIEF DESCRIPTION OF THE FIGURES
[0013] FIG. 1 is a top view of the stand support of the invention.
[0014] FIG. 2 is a top planar view of the stand support of the invention.
[0015] FIG. 3 is a side view of the device of the invention.
[0016] FIG. 4 is another side view of the stand support of the invention.
[0017] FIG. 5 is a bottom view of the stand support of the invention.
[0018] FIG. 6 shows a dissected view of the device of the invention.
[0019] FIG. 7 illustrates an inside view of the device of the invention.
[0020] FIG. 8 is a perspective view of the stand support of the invention.
[0021] FIG. 9 is a side elevational view of the stand in use in supporting a trailer.
[0022] It should be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein.
SUMMARY OF THE INVENTION
[0023] The instant invention provides a jack stand and safety support comprising: four sides that substantially form a pyramid; two of said four sides being opposite each other and including cut outs and handles; a top including a three tier basin that includes an optional drainage channel extending across all tiers and glow in the dark lengthwise strips along the corners of said jack stand and support.
[0024] The present invention also provides a safety support base for a trailer to eliminate the chance of it accidentally falling off the homemade block it sits on, preventing costly damage and possible injury or death. It also provides additional safety features with its bright hunters orange body and built in military style luminescent base and edges, providing an illuminated perimeter around you and your property to warn other drivers of your location at night.
[0025] The support base or stand comes in different sizes to accommodate specific style trailers. The stand is the standard size block which could be used for traditional RVs, Boat, ATV, or pull behind utility trailer. Larger sizes or heavy duty blocks are designed to be used with 5th wheels and works the same way. The small size is a low profile block which could be combined with other sizes and is used as a scissor jack support and illuminated perimeter. The supports or stands of the invention are equipped with military grade glow in the dark strips allowing your trailer to be seen from a distance and allowing you to recognize the location of the hitch during dark hours to prevent you from bumping into it and injuring yourself
[0026] The support or stand of the invention is a pyramid shaped plastic block that is light weight, and comes in a bright hunters orange colors with military grade glow in the dark strips on its edges and base for high visibility. It has built-in inverted handles for easy carrying and positioning. It also has an indented square pocket located on the top to allow the jack stand foot to fit into the “pocket”. The design allows the trailer jack stand to securely sit into the stand or support, preventing it from sliding off the block. The wide base and pyramid design also prevents the block from tipping over in the event of an earthquake, high winds or shifting of the trailer or the ground beneath it.
[0027] The smaller sizes are also pyramid shaped, light weight plastic block in a bright hunter's orange with military grade glow in the dark strips on its edges and base for high visibility. It also has a deep pocket which allows the scissor jack foot to securely fit into it preventing it from digging into the surface underneath it and helping to provide a safer and more sturdy foundation.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The stationary jack stand/support shown in the accompanying drawings and described below are examples which embody the invention. It should be noted that the scope of the invention is defined by the accompanying claims, and not necessarily by specific features of exemplary embodiments.
[0029] For the convenience of the reader, and with respect to FIGS. 1 , 3 , 5 , 6 , 7 and 8 the following correlation between reference numbers and elements of the invention is provided:
1 represents the pyramid base support 2 is the pyramid base with carved outs for handles 3 pyramid base side wall 4 pyramid base side wall with cut out and molded handles 5 are the molded handles 6 pyramid base top 7 is a 3 tier jack stand support basin 8 first tier is a rectangular jack stand foot support 9 second tier is a circular jack stand foot support 10 third tier is a wheeled jack stand foot support 11 is an optional drainage channel extending through all the tiers 12 drain holes located on the third tier 13 glow in the dark corner strips 14 molded base support ribs 15 empty cavities next to support ribs
[0045] With respect to FIGS. 2 , 4 , and 9 the following correlation between reference numbers and elements of the invention is provided:
1 , 2 , 3 , 4 represents the base grip of the support which can be made of rubber or other polymeric or metallic materials that are suitable for such base grip and may also contain grooves. 5 , 6 , 7 , 8 , represent the top of the pyramidal support of the invention. 9 , 10 , 11 , 12 are glow in the dark base lip 13 , 14 , 15 , 16 are the pyramid base edges 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 are glow in the dark edging strips 25 , 26 are molded system handles 27 , 28 are molded indented hand grooves for handles 29 indented jack stand support stabilizing basin 30 , 31 , 32 , 33 represent jack stand support stabilizing basin drain holes, 34 molded base support system 35 molded base support system drain grooves 37 draw bar 38 trailer 42 , 43 , pyramid base wall without handles 44 , 45 pyramid base wall with molded handles and hand grooves
[0061] FIG. 1 illustrates a top view of the jack stand or support of the invention 46 comprising base 1 and base 2 having cut outs for handles, four side walls designated a numerals 3 and 4 , where side wall 4 includes the cut outs and handles 5 , and a top 6 . The four side walls 3 and 4 extend upward from the base 1 and 2 to substantially form a pyramid. The top 6 of the support of the invention includes a three tier jack stand support basin 7 , that includes a rectangular jack stand foot support 8 , a circular jack stand foot support 9 and a wheeled jack stand foot support 10 . The support basin 7 includes an optional drainage channel 11 extending through all the tiers, drain holes 12 located on wheeled jack stand support 10 . The jack stand or support of the invention also includes glow in dark corner strips 13 . The glow in the dark corner strips 13 can be luminescent strips, chemiluminescent strips or electrochemiluminescent strips. The corner glow in the dark strips run lengthwise from the bottom of the pyramid to the top of the pyramid.
[0062] FIG. 2 is another view of the jack stand and support of the invention illustrating a base grip of the support shown by numerals 1 , 2 , 3 , 4 which can be made of rubber or other polymeric or metallic materials or plastic composites that are suitable for such base grip and may optionally contain grooves. The device of the invention further has a top shown by numerals 5 , 6 , 7 , 8 and a glow in the dark base lip designated by 9 , 10 , 11 , 12 . Reference numerals 13 , 14 , 15 , 16 designate the pyramid base edges and the glow in the dark edging strips are shown by numerals 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 . The device further includes molded handles 25 and 26 and also includes molded indented hand grooves 27 , 28 for handles. The top of the jack stand and support has a stabilizing basin 29 and the basin also includes drain holes 30 , 31 , 32 , 33 . Reference numerals 42 and 43 illustrate the pyramid base wall without handles, while reference numerals 44 and 45 denotes a pyramid base wall with molded handles and hand grooves.
[0063] FIG. 3 is a side view of the jack stand or support 46 of the invention illustrating the base 2 , handle 5 , side wall 4 , top 6 and glow in the dark corner strips 13 .
[0064] FIG. 4 is a side view of the embodiment of FIG. 2 wherein 46 is the device of the invention. The device includes a base grip for the support shown by reference numerals 1 , 2 , 3 , 4 which can be made of rubber or other polymeric or metallic materials or plastic composites that are suitable for such base grip and may optionally contain grooves. The device of the invention further has a top shown by numerals 5 , 6 , 7 , 8 and a glow in the dark base lip designated by 9 , 10 , 11 , 12 . Reference numerals 13 , 14 , 15 , 16 designate the pyramid base edges and the glow in the dark edging strips are shown by numerals 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 . The device further includes molded handles 25 and 26 and also includes molded indented hand grooves 27 , 28 for handles. The top of the jack stand and support has a stabilizing basin 29 and the basin also includes drain holes 30 , 31 , 32 , 33 . Reference numerals 42 and 43 illustrate the pyramid base wall without handles, while reference numerals 44 and 45 denotes a pyramid base wall with molded handles and hand grooves.
[0065] FIG. 5 is a bottom view of the jack stand or support 46 of the invention illustrating base 1 and base 2 , handles 5 , drainage holes 12 on tier 10 and support ribs 14 on molded base 1 and base 2 .
[0066] FIG. 6 is a dissected view of the jack stand and safety support of the invention illustrating base 1 , side walls 3 , and top 6 . The top 6 of the support of the invention includes a three tier jack stand support basin 7 , that includes a rectangular jack stand foot support 8 , a circular jack stand foot support 9 and a wheeled jack stand foot support 10 .
[0067] FIG. 7 is a side view of the device 46 of the invention illustrating the inside aspects of the device. The device 46 of FIG. 7 includes a base 1 and a top 6 . The top 6 of the support of the invention includes a three tier jack stand support basin 7 , that includes a rectangular jack stand foot support 8 , a circular jack stand foot support 9 and a wheeled jack stand foot support 10 . The support basin 7 optionally includes an optional drainage channel 11 extending through all the tiers, drain holes 12 located on wheeled jack stand support 10 . The jack stand or support of the invention also includes glow in dark corner strips 13 . The glow in the dark corner strips 13 can be luminescent strips, chemiluminescent strips or electrochemiluminescent strips. The corner glow in the dark strips run lengthwise from the bottom of the pyramid to the top of the pyramid. The device 46 of FIG. 7 as shown on the inside includes molded support ribs 14 and empty cavities 15 next to the support ribs.
[0068] FIG. 8 is a perspective view of the jack stand or support 46 of the invention showing base 1 and base 2 , side walls 3 and 4 , handle 5 , and top 6 . The top 6 of the support of the invention includes a three tier jack stand support basin 7 , that includes a rectangular jack stand foot support 8 , a circular jack stand foot support 9 and a wheeled jack stand foot support 10 . The support basin 7 includes an optional drainage channel 11 extending through all the tiers, drain holes 12 located on wheeled jack stand support 10 . The jack stand or support of the invention also includes glow in dark corner strips 13 .
[0069] In an embodiment of the invention chosen for the purpose of illustration, there is shown a stationary jack support/stand device 46 typified in use supporting a draw bar 37 of a trailer 38 as shown in FIG. 9 .
[0070] The device of the invention can be manufactured using conventional molding techniques known in the art of engineering thermoplastics.
[0071] The contents of all references cited in the instant specifications and all cited references in each of those references are incorporated in their entirety by reference herein as if those references were denoted in the text.
[0072] The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.
[0073] While the many embodiments of the invention have been disclosed above and include presently preferred embodiments, many other embodiments and variations are possible within the scope of the present disclosure and in the appended claims that follow. Accordingly, the details of the preferred embodiments and examples provided are not to be construed as limiting.
[0074] It is to be understood that the terms used herein are merely descriptive rather than limiting and that various changes, numerous equivalents may be made without departing from the spirit or scope of the claimed invention.
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The present invention relates to a jack stand and safety support comprising: four sides that substantially form a pyramid; two of said four sides being opposite each other including cut outs and handles; a top including a three tiers basin that includes an optional drainage channel extending across all tiers and drainage holes and glow in the dark lengthwise strips along the corners of said jack stand and support.
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RELATED APPLICATIONS
This application is a continuation-in-part of copending application Ser. No. 938,892, filed Dec. 8, 1986, now U.S. Pat. No. 4,714,115.
FIELD OF THE INVENTION
This invention relates to the hydraulic fracturing of subterranean formations and more particularly to the forming of a vertical hydraulic fracture in a subterranean formation that is normally disposed to form a horizontal hydraulic fracture.
BACKGROUND OF THE INVENTION
In the completion of wells drilled into the earth, a string of casing is normally run into the well and a cement slurry is flowed into the annulus between the casing string and the wall of the well. The cement slurry is allowed to set and form a cement sheath which bonds the string of casing to the wall of the well. Perforations are provided through the casing and cement sheath adjacent the subsurface formation. Fluids, such as oil or gas, are produced through these perforations into the well.
Hydraulic fracturing is widely practiced to increase the production rate from such wells. Fracturing treatments are usually performed soon after the formation interval to be produced is completed, that is, soon after fluid communication between the well and the reservoir interval is established. Wells are also sometimes fractured for the purpose of stimulating production after significant depletion of the reservoir.
Hydraulic fracturing techniques involve injecting a fracturing fluid down a well and into contact with the subterranean formation to be fractured. Sufficiently high pressure is applied to the fracturing fluid to initiate and propagate a fracture into the subterranean formation. Proppant materials are generally entrained in the fracturing fluid and are deposited in the fracture to maintain the fracture open.
Several such hydraulic fracturing methods are disclosed in U.S. Pat. Nos. 3,965,982; 4,067,389; 4,378,845; 4,515,214; and 4,549,608 for example. It is generally accepted that the in-situ stresses in the formation at the time of such hydraulic fracturing generally favor the formation of vertical fractures in preference to horizontal fractures at depths greater than about 2000 to 3000 ft. while at shallower depths such in-situ stresses can favor the formation of horizontal fractures in preference to vertical fractures.
For oil or gas reservoirs found at such shallow depths, significant oil or gas production stimulation could be realized if such reservoir were vertically fractured. For example, steam stimulation of certain heavy oil sands would be enhanced and productivity would be optimized in highly stratified reservoirs with low vertical permeability.
It is therefore a specific object of the present invention to provide for a hydraulic fracturing method that extends a propagated vertical fracture in a subsurface formation where the in-situ stresses favor a horizontal fracture.
SUMMARY OF THE INVENTION
The present invention is directed to a hydraulic fracturing method for extending a propagated vertical fracture in an earth formation surrounding a borehole wherein the original in-situ stresses favor a horizontal fracture.
In the practice of this invention an aqueous slug, containing a chemical blowing agent and a surfactant, is injected into a first depth within said borehole. The blowing agent is sensitive to formation heat. Subsequently, a fracturing fluid is injected behind said slug at the first depth. The fracturing fluid is pumped at a rate and pressure sufficient to propagate a horizontal fracture as favored by the original in-situ stresses. Thereafter, the chemical blowing agent decomposes and creates foam and pressure which extends the propagated fracture to a substantially greater distance.
The propagation and extension of the horizontal fracture changes the in-situ stresses so as to favor the propagation of a vertical fracture. Thereafter, a fracturing fluid is applied to said borehole at a second depth while maintaining pressure on said horizontal fracture thereby causing the propagation of a now favored vertical fracture.
It is therefore an object of this invention to extend a propagated horizontal fracture to a substantially greater distance in a formation which allows a subsequently propagated vertical fracture to extend to a greater depth in said formation.
It is another object of this invention to provide for the propagation of hydraulic fractures to greater distances than heretofore possible with conventional hydraulic fracturing methods.
It is yet another object of this invention to alleviate injectivity problems by utilizing a single phase fracturing fluid which can both propagate and extend hydraulic fractures.
It is a still yet further object of this invention to provide for an in-situ foam and gas generation method which can extend propagated fractures.
It is a still even further object of this invention to increase the effectiveness of a fracturing fluid while reducing the amount of chemicals used to produce a pressure generating foam.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a borehole apparatus penetrating an earth formation to be hydraulically fractured in accordance with the present invention.
FIG. 2 is a pictorial representation of hydraulic fractures, formed in the earth formation by use of the apparatus of FIG. 1.
FIG. 3 is a partial view of the bottom portion of the apparatus of FIG. 1 showing additional features of an alternate embodiment in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1 there is shown formation fracturing apparatus within which the hydraulic fracturing method of the present invention may be carried out. A wellbore 1 extends from the surface 3 through an overburden 5 to a shallow productive formation 7 where the in-situ stresses favor a horizontal fracture. Casing 11 is set in the wellbore and extends from a casing head 13 to the productive formation 7. The casing 11 is held in the wellbore by a cement sheath 17 that is formed between the casing 11 and the wellbore 1. The casing 11 and cement sheath 17 are perforated at 24 where the local in-situ stresses favor the propagation of a horizontal fracture and at 26 where the local in-situ stresses also favor the propagaton of a horizontal fracture. A tubing string 19 is positioned in the wellbore and extends from the casing head 13 to the lower end of the wellbore below the perforations 26. A packer 21 is placed in the annulus 20 between the perforations 24 and 26. The upper end of tubing 19 is connected by a conduit 27 to a source 29 of fracturing fluid. A pump 31 is provided in communication with the conduit 27 for pumping the fracturing fluid from the source 29 down the tubing 19. The upper end of the annulus 20 between the tubing 19 and the casing 11 is connected by a conduit 37 to the source 29 of fracturing fluid. A pump 41 is provided in fluid communication with the conduit 37 for pumping fracturing fluid from the source 29 down the annulus 20.
In carrying out the hydraulic fracturing method of the present invention with the apparatus of FIG. 1 in a zone of the formation where the in-situ stresses favor a horizontal fracture, such a horizontal fracture 42 is initially propagated by activating the pump 41 to force fracturing fluid down the annulus 20 as shown by arrows 35 through the performations 24 into the formation as shown by arrows 36 at a point immediately above the upper packer 21. The fact that this will be a horizontal fracture in certain formations can best be seen by reference to FIG. 2 where three orthogonal principle original in-situ stresses are operative. These in-situ stresses are a vertical stress (σ v ) of 1800 psi for example, a minimum horizontal stress (σ h min) of 1100 psi for example, and a maximum horizontal stress (σ h max) of 1300 psi for example. It is generally accepted that the in-situ stresses in the formation at the time of hydraulic fracturing generally favor the formation of vertical fractures in preference to horizontal fractures at depths greater than about 2000 to 3000 ft. while at shallower depths such in-situ stresses can favor the formation of horizontal fractures in preference to vertical fractures.
The mean horizontal stress (σ h ) is, therefore 1200 psi. This results in a ratio of mean horizontal stress to vertical stress (σ h /σ v ) of 0.667. Using this value and the equations set forth in "Introduction to Rock Mechanics" by R. E. Goodman, John Wiley and Sons, N.Y., 1980, pps. 111-115, a vertical stress of greater than 2000 psi is required for a vertical fracture to form. Typical ranges of σ h /σ v are 0.5 to 0.8 for hard rock and 0.8 to 1.0 for soft rock such as shale or salt. For the foregoing example, a fluid pressure of 1900 psi is maintained during the initial propagation of a horizontal fracture 42 by controlling the fracturing fluid flow rate through annulus 20 or by using well known gelling agents.
Due to the pressure in the horizontal fracture 42, the local in-situ stresses in the formation 7 are now altered from the original stresses of FIG. 2 to favor the formation of a vertical fracture 43. Such a vertical fractures 43 can thereafter be formed in formation 7 by activating the pump 31 to force fracturing fluid out the bottom of tubing 19 as shown by arrows 38 and through the perforations 26 into the formation as shown by arrows 39 at a point near the bottom of the wellbore. This vertical fracture 43 is propagated while maintaining the fluid pressure on the horizontal fracture 42, which can either be stabilized in length or still propagating.
The height of vertical fracture 43 is relative to that of the horizontal fracture 42. For an essentially circular horizontal fracture, the height of the vertical fracture is about equal to the diameter of the horizontal fracture. Should the vertical fracture become too large relative to the horizontal fracture, it will curve and eventually become a horizontal fracture at some distance from the well.
The distance that the horizontal fracture travels from the well can be extended by incorporating into the fracturing ("frac") fluid a chemical for generating additional pressure. These chemical comprise a chemical blowing agent and a surfactant which are added into an aqueous solution sufficient to create a foam. The amount of chemical blowing agent utilized will be from about 0.51% to about 5.0% by weight. The amount of surfactant utilized will be an amount sufficient for foam stabilization and will generally be from about 0.1% to about 2% by weight. After mixing the blowing agent and surfactant together in an aqueous medium, a slug of the aqueous medium, containing said surfactant and chemical blowing agent in an amount sufficient to generate a volume of gas sufficient to create a fracturing pressure to extend the horizontal fracture, is placed into the frac fluid. After this slug has been injected into the formation to a desired distance, additional frac fluid is injected into a first depth within the perforated casing. The formation is fractured at the first depth thus creating a horizontal fracture. Once the horizontal fracture has propagated to its greatest extent, heat of the formation being in excess of about 125° F. causes the chemical blowing agent to decompose thereby liberating a gas sufficient to create foam and a pressure buildup. Pressure is maintained on the formation while the propagated horizontal fracture extends to a greater distance into the formation.
While pressure is being maintained on the horizontal fracture, fracturing fluid is supplied to the formation at a second depth within said borehole. Said fracturing fluid enters said second depth at a rate and pressure sufficient to create a vertical fracture. A vertical fracture is favored by the in-situ stresses as altered by the propagated and extended horizontal fracture. Since the horizontal fracture has been extended to a greater distance in the formation because of the in-situ foam generated therein, the propagated vertical fracture can be extended to a substantially greater distance before curving and being converted into a horizontal fracture.
The distance that the vertical fracture travels before curving and converting into a horizontal fracture can be extended even further. This is accomplished by placing alternate aqueous slugs into the formation via the first fracture which slugs contain increased amounts of a chemical blowing agent and a surfactant thereby producing more foam and generating additional pressure. The distance that the horizontal fracture has traveled is then determined.
The effectiveness of fracturing at each stage of this method can be determined by available methods. One such method is described in U.S. Pat. No. 4,415,805 issued to Fertl et al. This patent is incorporated herein by reference. In this method a multiple stage formation fracturing operation is conducted with separate radioactive tracer elements injected into the well during each stage of the fracturing operation. After completion of the fracturing operation, the well is logged using natural gamma ray logging. The resulting signals are sorted into individual channels or energy bands characteristic of each separate radioactive tracer element. Results of the multiple stage fracturing operation are evaluated based on dispersement of the individual tracer elements.
If it is desired to extend the vertical fracture to that distance determined for the extended horizontal fracture, an aqueous slug containing a blowing agent and a surfactant can be used as mentioned above when the horizontal fracture was extended. This may particularly be required when the fracture has extended beyond the distances obtainable via conventional hydraulic fracturing methods.
The method of this invention can be practiced by incorporating a chemical blowing agent and a surfactant into the frac fluid. Afterwards the frac fluid can be injected into the formation. The blowing agent selected could comprise one which will become active only after hydraulic fracturing has occurred. Chemical blowing agents which can be utilized herein include dinitrosopentamethylenetetramine (DNPT), blends of sodium hydrogen carbonate, and nitrogen releasing agents such as p-toluene sulfonyl hydrazide and p,p'-oxybis(benzenesulfonyl hydrazide). Other chemical blowing agents which can be utilized include azodicarbonamide, and salts of azodicarboxylic acid.
DNPT and sodium hydrogen carbonate can be used in conjunction with normal waterflooding operations. Since DNPT is only slightly soluble in cold water, warm water is required to achieve significant water solubility. Warm water can be obtained by preheating water to be injected or reinjection of warm produced water. Enhancement of the low temperature solubility of DNPT can be obtained by the use of chemicals. Said chemicals include dimethylformamide (DMF) and dimethylsulfoxide (DMSO). As will be understood by those skilled in the art, the amount of chemical utilized will depend upon such factors as the amount and temperature of water utilized, chemical composition of the water, and the amount of DNPT utilized.
Although sodium hydrogen carbonate and other bicarbonate foaming agents can be utilized, they are limited by an equilibrium which reduces yield with increasing pressure. To overcome this limitation, bicarbonate decomposition can be pH drive with formulations containing suitable compounds for pH depression with temperature increase. One such compound is the nitrogen releasing blowing agent, p-toluene sulfonyl hydrazide. Bicarbonate decomposition generates carbon dioxide. The addition of a suitable amount of p-toluene sulfonyl hydrazide, which generates acidic compounds upon decomposition, causes substantially increased volumes of carbon dioxide to be released from solution due to bicarbonate decomposition.
Azodicarbonamide similar to DNPT is soluble in water only at elevated temperatures. Since azodicarbonamide is available in powder form with average particle size in the micron range, solid dispersions can be utilized. A dispersion can be made by placing micron sized azodicarbonamide in a suitable surfactant solution. The amount of azodicarbonamide should be sufficient to create the volume of gas required to obtain a fluid diversion effect. One such suitable class of surfactants is the alkyl napthelene sulfonates, which can be purchased from GAF as the Nekel series, located in New York. Should it be desired to accelerate the decomposition of azodicarbonamide, an alkali carbonate can be utilized to obtain decomposition from the injection point to a desired distance in the formation. Alkali carbonates which can be utilized include sodium carbonate and potassium carbonate. Thus, azodicarbonamide will prove to have enhanced potential for use in carbonate reservoirs. Azodicarbonamide can be included in a microemulsion for injection into the formation. A method for making a microemulsion is disclosed in U.S. Pat. No. 4,008,769 which issued to Chang on Feb. 22, 1977. This patent is incorporated by reference herein.
The sodium salt of azodicarboxylic acid can be used as a chemical blowing agent. This blowing agent can be formed on site by the treatment of azodicarbonamide with sodium hydroxide and alkali carbonate with resulting ammonia evolution. When heated, this salt liberates nitrogen and carbon dioxide, yet it is very stable at room temperature in basic solutions having a pH greater than 12. The pH decline from hydroxide consumption will accelerate the foam decomposition reaction. Toluene sulfonyl hydrazide and p,p'-oxybis(benzenesulfonyl hydrazide) also develop water solubility at high pH, but the modified azodicarbonamide is preferred.
Examples of suitable surfactants comprise nonionic and anionic surfactants, commercially available sodium dodecylbenzene sulfonates, e.g., Siponate DS-10 available from American Alcolac Company, mixtures of the Siponate or similar sulfonate surfactants with sulfated polyoxyalkylated alcohol surfactants, e.g., the NEODOL sulfate surfactants available from Shell Chemical Company; sulfonate sulfate surfactant mixtures, e.g., those described in the J. Reisberg, G. Smith and J. P. Lawson U.S. Pat. No. 3,508,612; petroleum sulfonates available from Bray Chemical Company; Bryton sulfonates available from Bryton Chemical Company; Petronates and Pyronates available from Sonnoborn Division of Witco Chemical Company; fatty acid and tall oil acid soaps, e.g., Actynol Heads from Arizona Chemical Company; nonionic surfactants, e.g., Triton X100; and the like surfactant materials which are soluble or dispersible in aqueous liquids. These surfactants are disclosed in U.S. RE Pat. No. 30,935 which issued to Richardson et al. on May 18, 1982. This patent is incorporated herein by reference.
Water used to mix the chemical blowing agents and surfactant can comprise fresh water, formation water, brackish water, or salt water.
In both embodiments, the chemical blowing agent is selected on the basis of reservoir temperature, mineralogy, depth, and environmental conditions. As required, pH buffers, accelerators, or inhibitors can be incorporated into the aqueous chemical slug prior to injection into the formation or reservoir. Choice of accelerators or inhibitors would be specific to the selected blowing agent. Accelerators which can be used for azodicarbonamide include alkali carbonates, basic metal salts of lead, cadmium, or zinc such as dibasic lead phthalate, and polyols such as glycols and glycerol. Inhibitors which can be utilized include barium salts and neutral pH buffers. Accelerators which can be used for DNPT include mineral acids and salts of mineral acids such as zinc chloride. Stabilizers which can be used for DNPT include oxides, hydroxides, or carbonates of calcium, barium, zinc, or magnesium. The size of the chemical slug would depend upon the extent of the prescribed treatment area. The injection rate of the chemical slug should be sufficient to allow fluid placement into the zone or zones desired to be treated prior to significant gas release. Bubbles or foam generated in a high permeability zone will lead to flow diversion and enhanced sweep of the formation or reservoir.
Obviously, many other variations and modifications of this invention as previously set forth may be made without departing from the spirit and scope of this invention as those skilled in the art readily understand. Such variations and modifications are considered part of this invention and within the purview and scope of the appended claims.
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A method for extending a vertical fracture formed in a formation having original in-situ stresses that favor the propagation of a horizontal fracture. In this method, a subsurface formation having original in-situ stresses that favor the propagation of a horizontal fracture is penetrated by a cased borehole which is perforated at a pair of spaced-apart intervals to form separate pairs of perforations. Fracturing fluid is initially pumped down said cased borehole and out one of said sets of perforations to form the originally favored horizontal fracture. The propagation of this horizontal fracture changes the in-situ stresses so as to favor the propagation of a vertical fracture. Said horizontal fracture is extended by placing a chemical blowing agent and surfactant into the fracturing fluid. Gas released by decomposition of said agent causes foam to be generated along with an increase in pressure thereby extending the horizontal fracture. Thereafter, while maintaining pressure on said horizontal fracture, fracturing fluid is pumped down said cased borehole and out of the other of said sets of perforations to form the newly favored vertical fracture.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national phase application of International Application No. PCT/JP2011/073080, filed Oct. 6, 2011, the content of which is incorporated herein by reference.
TECHNICAL FIELD
The present invention relates to an engine startup system that, during propulsion of a hybrid vehicle, starts an engine by employing the torque of an electric motor.
BACKGROUND ART
A hybrid vehicle is capable of operating in an EV propulsion mode in which it travels in the state with its engine stopped. An engine startup system is per se known (refer to Patent Document #1) in which, when a request for starting the engine is issued during the EV propulsion mode, the engine is started by transmitting the torque of the electric motor to the engine via a clutch, and temporarily in this starting process the clutch is disengaged or its engagement force is reduced; and then, when the starting of the engine has been completed and after the difference between the input and output rotational speeds of the clutch has disappeared, the clutch is engaged so that the propulsion mode is changed over. Moreover, Patent Documents #2-#4 mentioned below in the Citation List are relevant to the present invention.
CITATION LIST
Patent Literature
Patent Document #1: JP2005-162142A.
Patent Document #2: JP2005-162081A.
Patent Document #3: JP2011-16390A.
Patent Document #4: JP2007-261395A.
SUMMARY OF INVENTION
Technical Problem
The clutch disengagement operation in Patent Document #1 is started upon the condition that the rotational speed at which the engine is being cranked has reached a predetermined speed at which starting is possible. However, since the clutch is disengaged when the rotational speed of the engine has reached this speed at which starting is possible, accordingly the interval required from when the rotational speed of the engine reaches this speed at which starting is possible until starting of the engine is completed does not change. In other words, if the condition for starting the clutch disengagement operation is invariant, it is not possible to vary the time period from when the request for starting the engine is issued until changing over of the propulsion mode. Due to this there is a danger that the responsiveness of the drive force may be deteriorated, since, in a state in which the required drive force is great, changing over of the propulsion mode becomes relatively slow.
Thus, the object of the present invention is to provide an engine startup system, that is capable of providing drive force responsiveness corresponding to the demand for drive force.
Solution to Technical Problem
The engine startup system of the present invention is an engine startup system that is applied to a hybrid vehicle in which an engine is linked via a clutch to a power transmission path that outputs drive force for propulsion and in which also an electric motor is linked to the power transmission path comprising an electronic control unit configured to start up the engine by employing the torque of the electric motor when a startup request for the engine is issued during a propulsion mode in which the engine is stopped, engage the clutch so that torque after starting of the engine is transmitted to the power transmission path, perform semi-engagement operation of engaging the clutch while slipping it in order to crank the engine and disengagement operation of disengaging the clutch after cranking of the engine has started, and change the start timing of the disengagement operation according to required drive force.
Since, according to this engine startup system, the start timing of the clutch disengagement operation is varied according to the required drive force, accordingly the time period required until changeover of the propulsion mode comes to correspond to the required drive force. Due to this, it is possible to obtain a drive force responsiveness that corresponds to the required drive force.
As one aspect of the engine startup system of the present invention, when the required drive force is lower than a predetermined reference value, the electronic control unit may set the start timing of the disengagement operation so that the disengagement operation starts at a timing that a starting possible condition for starting of the engine by the semi-engagement operation to become possible becomes valid. Since, according to this aspect, the clutch disengagement operation is performed when the starting possible condition becomes valid due to the semi-engagement operation, accordingly it is possible reliably to prevent the occurrence of vibration due to the engine side rotational speed of the clutch becoming higher than its power transmission path side rotational speed.
In this aspect of the present invention, the electronic control unit may set the start timing of the disengagement operation by taking, as being the time point at which the starting possible condition becomes valid, the time point at which the energy possessed by the engine during the semi-engagement operation arrives at a self-starting energy with which, even if the disengagement operation is performed, the rotational speed of the engine can be maintained without dropping below a predetermined limit level at which starting is possible until the timing of initial firing. In this case, due to the disengagement operation being performed at the timing that the energy possessed by the engine arrives at the self-starting energy, the rotational speed of the engine is maintained without dropping below the limit level at which starting is possible until the timing of initial firing of the engine. Due to this, it is possible to make the start timing of the disengagement operation earlier, within the limit of it being possible to implement reliable engine starting. Accordingly, it is possible to reduce the energy that is lost due to the semi-engagement operation.
As one aspect of the engine startup system of the present invention, when the required drive force is greater than a predetermined reference value, the electronic control unit may set the start timing of the disengagement operation on the basis of the engine side rotational speed and the power transmission path side rotational speed of the clutch. According to this aspect, it is possible for the start timing of the disengagement operation to be set in consideration of the speed difference between the engine side rotational speed and the power transmission path side rotational speed.
In this aspect of the present invention, the electronic control unit may set the start timing of the disengagement operation so that the start timing of the disengagement operation is delayed, upon the condition that the engine side rotational speed is not greater than the power transmission path side rotational speed. In this case, it is possible to delay the start timing until the limit at which it is possible to prevent the occurrence of vibration generated due to the engine side rotational speed of the clutch being higher than its power transmission path side rotational speed. Since, due to this, it is possible to start the engine while raising the rotational speed of the engine until directly before vibration occurs, accordingly it is possible to complete the changeover of the propulsion mode at an early stage. Accordingly, it is possible to enhance the responsiveness of the drive force in a situation in which the required drive force is large and high responsiveness of the drive force is demanded.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a figure showing an outline of a vehicle to which a startup system according to an embodiment of the present invention is applied;
FIG. 2 is a flow chart showing an example of a control routine for startup control;
FIG. 3 is a flow chart showing an example of a control routine for a first disengagement operation defined by the routine of FIG. 2 ;
FIG. 4 is a flow chart showing an example of a control routine for a second disengagement operation defined by the routine of FIG. 2 ;
FIG. 5A is a timing chart showing an example of the result of control when the required drive force is greater than a reference value;
FIG. 5B is a timing chart showing an example of the result of control when the required, drive force is less than or equal to the reference value; and
FIG. 6 is a figure showing an example of another vehicle to which a startup system according to the present invention can be applied.
DESCRIPTION OF EMBODIMENTS
As shown in FIG. 1 , a vehicle 1 is built as a so-called hybrid vehicle that, as power sources for propulsion, is provided with an internal combustion engine 2 and a motor-generator 3 that functions as an electric motor. The internal combustion engine 2 (hereinafter termed the “engine”) is built as a spark ignition type internal combustion engine. An output shaft 2 a of the engine 2 is connected to an automated manual transmission (AMT) 8 via an electromagnetic clutch 7 . Engagement operation and disengagement operation are performed by the electromagnetic clutch 7 , matched to speed change operation of the AMT 8 . Moreover, it is possible to vary the power transmission ratio of the electromagnetic clutch 7 in an almost stepless manner by varying the intensity of the electrical current supplied thereto. Accordingly, by controlling the intensity of the current supplied to the electromagnetic clutch 7 , it is possible to perform semi-engagement operation in which the electromagnetic clutch 7 is allowed to slip somewhat while it is being engaged.
The AMT 8 is capable of selecting any one speed, change stage from among a plurality of four forward speed change stages. Selection by the AMT 8 of a speed change stage is performed automatically on the basis of the speed of the vehicle 1 and the accelerator opening amount. Moreover, by the AMT 8 being changed over to a manual mode, the driver may select any desired speed change stage by operating a shift knob not shown in the figures.
The AMT 8 comprises an input shaft 10 and an output shaft 11 that extends parallel thereto, and first through, fourth gear pairs G 1 through G 4 are provided between this input shaft 10 and output shaft 11 . The first through fourth gear pairs G 1 through G 4 correspond to the first through the fourth speeds. It should be understood that reverse propulsion of the vehicle 1 is implemented by operating the motor-generator 8 backwards in the state in which the first speed is selected. The first gear pair G 1 includes a first drive gear 13 and a first driven gear 14 that are mutually meshed together. And the second gear pair G 2 includes a second drive gear 15 and a second driven gear 16 that are mutually meshed together. Likewise, the third gear pair G 3 includes a third drive gear 17 and a third driven gear 18 that are mutually meshed together. And the fourth gear pair G 4 includes a fourth drive gear 19 and a fourth driven gear 20 that are mutually meshed together. The gear ratios of the gear pairs G 1 through G 4 are set to become smaller in the following order; the first gear pair G 1 , the second gear pair G 2 , the third gear pair G 3 , and the fourth gear pair G 4 .
The first drive gear 13 and the second drive gear 15 are both provided upon the input shaft 10 so as to rotate integrally together with the input shaft 10 . On the other hand, the third drive gear 17 and the fourth drive gear 19 are both provided upon the input shaft 10 so as to be capable of rotating relatively to that input shaft 10 . The first driven gear 14 and the second driven gear 16 are both provided upon the output shaft 11 so as to be capable of rotating relatively to the output shaft 11 . On the other hand, the third driven gear 18 and the fourth driven gear 20 are both provided upon the output shaft 11 so as to rotate integrally together with that output shaft 11 .
Coupling devices C 1 through C 4 are provided for engaging one of the above described plurality of speed, change stages of the AMT 8 , Each of the coupling devices C 1 through C 4 is built as a meshing type clutch of a per se known type, and is operated by an operating mechanism not shown in the figures. The first coupling device C 1 is capable of operating between an engaged state in which it couples the first driven gear 14 to the output shaft 11 and thus makes the first driven gear 14 and the output shaft 11 rotate integrally together, and a disengaged state in which it disengages this coupling. In a similar manner, the second coupling device C 2 is capable of operating between an engaged state in which it couples the second driven gear 16 to the output shaft 11 and thus makes the second driven gear 16 and the output shaft 11 rotate integrally together, and a disengaged state in which it disengages this coupling. Moreover, the third coupling device C 3 is capable of operating between an engaged state in which it couples the third drive gear 17 to the input shaft 10 and thus makes the third drive gear 17 and the input shaft 10 rotate integrally together, and a disengaged state in which it disengages this coupling. In a similar manner, the fourth coupling device C 4 is capable of operating between an engaged state in which it couples the fourth drive gear 19 to the input shaft 10 and thus makes the fourth drive gear 19 and the input shaft 10 rotate integrally together, and a disengaged state in which it disengages this coupling. The AMT 3 is capable of engaging one of the above described plurality of speed change stages by putting one of these coupling devices C 1 through C 4 into the engaged state.
A first output gear 21 is provided upon the output shaft 11 so as to rotate integrally therewith. This first output gear 21 is meshed with a ring gear 26 provided upon a casing of a differential mechanism 25 that is linked to drive wheels not shown in the figures. The torque outputted from the AMT 8 is transmitted to the left and right drive wheels via the ring gear 26 and the differential mechanism 25 . The power transmission path from the AMT 8 to the drive wheels corresponds to the “power transmission path” in the Claims of the present application, since it is a path for outputting drive force for propulsion. The torque of the motor-generator 3 is transmitted to the output shaft 11 via a gear train 28 . The gear train 28 includes a second output gear 29 that rotates integrally with the output shaft 11 and a motor drive gear 30 that rotates integrally together with a shaft 3 a of the motor while being in the state of meshing with the second output gear 29 .
Control of each of the engine 2 , the motor-generator 3 , the electromagnetic clutch 7 , and the AMT 8 is performed by an electronic control unit (ECU) 40 that is built as a computer unit. Control programs of various types for providing an adequate operational state of the vehicle 1 are stored in the ECU 40 . The ECU 40 performs control of control objects such as the engine 2 described above and so on by executing these programs. The ECU 40 is connected to various sensors that output information related to the operational state of the vehicle 1 . For example, an input side resolver 41 that outputs a signal corresponding to the rotational speed of the input shaft 10 , an output side resolver 42 that outputs a signal corresponding to the rotational speed of the output shaft 11 , a crank angle sensor 43 that outputs a signal corresponding to the crank, angle of the engine 2 , and an accelerator opening amount sensor 44 that outputs a signal corresponding to the accelerator opening amount are all electrically connected to the ECU 40 .
An example of the control functions performed by the ECU 40 is propulsion mode changeover control in which changeover is performed between propulsion modes of various types, such as a hybrid propulsion mode in which both the engine 2 and also the motor-generator 3 are employed as power sources for propulsion, an electric propulsion mode in which, with the engine 2 in the stopped state, only the motor-generator 3 is employed as a power source for propulsion, and so on. Stopping control and startup control of the engine 2 are performed together with this propulsion mode changeover control. Moreover, when the vehicle 1 is decelerating, regeneration control is also performed, in which power inputted from the drive wheels is taken advantage of for generation of electrical power by the motor-generator 3 , in the following, among the various types of control executed by the ECU 40 , forms of control related to the present invention will be explained, while explanation of other forms of control will be omitted or curtailed.
In some cases, in response to a demand for increase of the drive force during the electric propulsion mode, the ECU 40 starts the engine and changes over the propulsion mode from the electric propulsion mode to the hybrid propulsion mode. In order to implement starting of the engine 2 in this process of changing over the propulsion mode, the ECU 40 performs the startup control shown in FIG. 2 . The program of the FIG. 2 routine, which is stored in the ECU 40 , is read out in a timely manner and repeatedly executed at predetermined intervals of the order of a number of milliseconds.
In a first step S 1 , the ECU 40 makes a decision as to whether or not a request has been issued for startup of the engine 2 . If a startup request has been issued then the flow of control proceeds to a step S 2 , while if no such request has been issued then the subsequent processing is skipped and this iteration of the routine terminates. During travel in the electric propulsion mode, a startup request is issued when some starting up condition becomes valid, such as the required drive force increasing and exceeding a threshold value or the like.
In the step S 2 the ECU 40 starts semi-engagement operation, in which the electromagnetic clutch 7 is engaged while being somewhat slipped. Due to this semi-engagement operation, the torque of the motor-generator 3 is transmitted to the engine 2 via the AMT 6 , and thereby the engine 2 is cranked. And, along with starting this semi-engagement operation, the ECU 40 controls the motor-generator 3 so that the loss accompanying the semi-engagement operation is compensated for. Due to this, it is possible to prevent: the vehicle 1 from decelerating along with the semi-engagement operation. It should be understood that the ECU 40 performs firing of the engine 2 together with this semi-engagement operation.
Then, in a step S 3 , the ECU 40 makes a decision as to whether or not the drive force that is currently being required is greater than a predetermined reference value. If the required drive force is greater than this predetermined reference value then the flow of control proceeds to a step S 4 , whereas if the required drive force is less than or equal to this predetermined reference value then the flow of control is transferred to a step S 5 . The required drive force is calculated on the basis of the accelerator opening amount and the vehicle speed. And the accelerator opening amount is calculated on the basis of the signal of the accelerator opening amount sensor 44 , while the vehicle speed is calculated on the basis of the signal of the output side resolver 42 . The predetermined reference value is set in consideration of the requirement for responsiveness of the drive force. Accordingly, the relationship holding between the required drive force and the predetermined reference value is that: if the required drive force is greater than the predetermined reference value, then the level of the requirement for responsiveness is high; while, if the required drive force is less than or equal to the predetermined reference value, then the level, of the requirement for responsiveness is not high.
Next in a step S 4 the ECU 40 performs a first disengagement operation shown in FIG. 3 , in which it starts disengagement operation of the electromagnetic clutch 7 at a start timing that is suitable for a case in which the required drive force is large. First, in a step S 41 of FIG. 3 , the ECU 40 calculates an estimated value Nep for the engine side rotational speed during disengagement operation. It should be understood that, in this embodiment, the engine side rotational speed and the engine rotational speed are the same, since the electromagnetic clutch 7 and the engine 2 are directly coupled together. The engine side rotational speed means the rotational speed of a rotating element of the electromagnetic clutch 7 on its side that is connected to the engine 2 , while the rotational speed of the engine 2 means the rotational speed of its output shaft 2 a . When the disengagement operation of the electromagnetic clutch 7 is performed, the engine side rotational speed rises due to the engine firing. The faster this disengagement operation is performed, the more easily can shock occur. An operating speed for limiting the occurrence of shock, exists for each engine side rotational speed. Thus, the ECU 40 estimates the estimated value Nep by taking, as a condition, that the disengagement operation of the electromagnetic clutch 7 should be performed at the fastest timing, for the current engine side rotational speed, at which no shock is generated.
Then, in a step S 42 , the ECU 40 makes a decision as to whether or not this estimated value Nep is greater than the value obtained by subtracting a safety margin a from the rotational speed Nin of the input shaft 10 . The rotational speed Nin of the input shaft 10 is calculated on the basis of the signal of the input side resolver 41 . The rotational speed Nin corresponds to the “power transmission path side rotational speed” in the Claims of the present application. And the safety margin α is determined in consideration of the accuracy of estimation of the engine side rotational speed. If the result of the decision in this step S 42 is affirmative the flow of control proceeds to a step S 43 , whereas if the result is negative the flow of control returns to the step S 41 .
Finally, in the step S 43 , the ECU 40 starts the operation of disengagement of the electromagnetic clutch 7 . By setting the safety margin α of the step S 42 to an appropriate value that is not zero, it is possible to start the disengagement operation upon the condition that the engine side rotational speed is not greater than the rotational speed of the input shaft 10 . Since, the smaller the safety margin a is set, the more Immediately before the engine side rotational speed exceeds the rotational speed of the input shaft 10 the start timing of the disengagement operation occurs, accordingly the start timing of the disengagement operation is delayed by just this amount. The more the start timing of the disengagement operation is delayed, the more rapidly it is possible to raise the rotational speed of the engine 2 .
Returning to FIG. 2 , in a step S 5 , the ECU 40 performs a second disengagement operation shown in FIG. 4 , in which it starts disengagement operation of the electromagnetic clutch 7 at a start timing that is suitable for a case in which the required drive force is less than or equal to the predetermined reference value. First, in the step S 51 of FIG. 4 , the ECU 40 calculates the energy E possessed, by the engine 2 during semi engagement operation. This energy E is the total of the kinetic energy Ek, the positional energy Ep, the supplied energy Ea, and the lost energy Es. The concrete calculation of these energies may be performed by a per se known method. An outline of such a calculation is as follows. The kinetic energy Ek is calculated from the rotational speed of the engine 2 by using a per se known equation. The positional energy Ep is calculated on the basis of the crank angle of the engine 2 , the torque that originates due to its compression ratio, and its rotational speed. The supplied energy Ea is calculated on the basis of the clutch torque and the rotational speed, And the lost energy Es is calculated on the basis of the rotational speed of the engine 2 and the frictional torque.
Then, in a step S 52 , the ECU 40 makes a decision as to whether or not this energy E is greater than the self-starting energy β. The self-starting energy β is the energy with which, even though disengagement operation of the electromagnetic clutch 7 is performed, it is possible for the rotational speed of the engine 2 to be maintained until the timing of initial firing, without that rotational speed dropping below a predetermined limit level at which starting is possible. This limit level at which starting is possible is determined experimentally as an intrinsic value of the engine 2 . The self-starting energy β is a function of the rotational speed and the crank angle of the engine 2 . A map constructed experimentally in advance but not shown in the figures is stored in the ECU 40 , specifying this self-starting energy as a variable that depends upon the rotational speed and the crank angle of the engine 2 . The ECU 40 refers to this map and obtains the self-starting energy β corresponding to the current values of the rotational speed and crank angle of the engine 2 , and compares together the magnitudes of this self-starting energy β and the energy E. If the result of the decision in this step S 52 is affirmative the flow of control proceeds to a step S 53 , while if it is negative the flow of control returns to the step S 51 .
Finally, in the step S 53 , the ECU 40 starts the operation of disengagement of the electromagnetic clutch 7 . The proper timing for starting this disengagement operation in order for the disengagement operation to be performed in the case of an affirmative decision in the step S 52 is the time point at which the energy E arrives at the self-starting energy β. Accordingly, by performing the disengagement operation at this timing, the rotational speed of the engine 2 is maintained until the timing of initial firing of the engine 2 , without dropping below the limit level at which starting is possible. Due to this, it is possible to expedite the start timing of the disengagement operation to be as early as possible, up to the earliest limiting timing at which it is possible to implement reliable engine starting.
Returning to FIG. 2 , in a step S 6 , the ECU 40 makes a decision as to whether or not the rotational speed Ne of the engine 2 is greater than the rotational, speed Nin of the input shaft 10 . If the rotational speed Ne is greater than, the rotational speed Nin, then the flow of control proceeds to a step S 7 . But if the rotational speed Ne is less than or equal to the rotational speed Nin, then the flow of processing stops.
In the step S 7 , the ECU 40 performs engagement operation. This engagement operation is a per se known type of operation in which the electromagnetic clutch 7 is brought into the perfectly engaged, state by gradually increasing its torque transmission ratio. By this engagement operation being performed, the changeover to the propulsion mode in which the torque of the engine 2 after starting is transmitted to the input shaft 10 is completed.
By the control of FIGS. 2 through 4 being performed as explained above, the control results become different in the case of FIG. 5A in which the required drive force is larger and in the case of FIG. 5B in which the required drive force is smaller. As will be clear from these figures, the interval T 1 from the time point t 0 at which the startup request is issued for the semi-engagement operation of the electromagnetic clutch 7 to be started, until the start timing t 2 of disengagement operation at which the clutch torque Tq starts to drop, is longer in the case of FIG. 5A in which the required drive force is larger, and is shorter in the case of FIG. 5B in which the required drive force is smaller. Due to this, as shown in FIG. 5A , when the required drive force is large, the rotational speed of the engine 2 rises quickly, as compared to when the required drive force is small. As a result, when the required drive force is large, the time interval T 2 from, the time point t 2 when the disengagement operation starts to the time point t 3 at which the changeover of propulsion mode is completed becomes shorter, as compared to when the required drive force is small. And, due to this, it is possible to enhance the responsiveness of the drive force in a situation in which, the required drive force is large and good responsiveness of the drive force is demanded. On the other hand, when the required drive force is small, as a result of the time interval T 1 from the time point 10 at which the startup request is issued to the start timing t 2 of disengagement operation becoming shorter, the time interval T 2 from the starting time point t 2 of disengagement operation to the time point t 3 at which the changeover of propulsion mode is completed becomes longer. However, since it is possible to shorten the time interval for implementation of semi-engagement operation as much as possible upon the condition that the occurrence of vibration of the electromagnetic clutch 7 is suppressed, accordingly it is possible to reduce the amount of energy lost due to such semi-engagement operation.
Since in this manner, according to the startup system of this embodiment, the start, timing of the disengagement operation of the electromagnetic clutch 7 is changed according to the required drive force, accordingly the time period required for changing over the propulsion mode is made to correspond to the required drive force. Due to this, it is possible to obtain drive force responsiveness that corresponds to the required drive force.
The present invention is not to be considered as being limited, to the embodiment described above; it could be implemented in various different ways, provided that the scope of the gist of the present invention is preserved. In the embodiment described above, in a case in which the required drive force is less than a predetermined reference value, it would, be possible to employ, as the condition for starting being possible, that the rotational speed of the engine exceeds a predetermined limit level for starting to be possible.
The vehicle to which the engine startup system, of the present invention is applied is not to be considered, as being limited to the type shown in FIG. 1 . For example, as shown in FIG. 6 , it would also be possible to apply the present invention to a vehicle 1 ′ to which is mounted a transmission 60 that internally houses a motor-generator 61 that serves as an electric motor. The location in which the electric motor is mounted is not particularly limited. Accordingly, the electric motor may also be provided more towards the output side than the clutch. For example, the electric motor might be provided to a differential mechanism, to which the drive wheels are linked, or between the drive wheels and the differential mechanism. Furthermore, it would also be possible for the electric motor to be provided internally to one of the drive wheels, as an in-wheel motor. Moreover, the transmission that is mounted to the vehicle may be a dual clutch transmission (DCT), a continuously variable transmission (CVT), or an automatic transmission (AT).
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In the course of starting up an engine during electric travel node, this engine startup system performs a semi-engagement operation (S 2 ) of engaging the clutch while making same slip in order to crank the engine, and then performs a disengagement operation (S 4 , S 5 ) of disengaging the clutch after starting to crank the engine. The timing for starting the disengagement operation of the clutch is varied depending on the driving force required.
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